7e Conférence Canadienne de Biologie du Développement
7th Canadian Developmental Biology Conference
&
5e Conférence régionale Canada de la SDB
5th Canada Regional SDB Conference
Mont-Tremblant, Québec
Mars / March 17 – 20, 2014
Conference plénière / Keynote Lecture
Dr Claudio Stern
Organizers
Marie Kmita - Jacques Drouin
Michel Cayouette - Frédéric Charron
Artur Kania - Richard Roy
Mont-Tremblant, Québec
Mars / March 17 – 20, 2014
LUNDI / MONDAY, MARCH 17 MARS
16:00 – 20:00 Inscription / Registration
17:30 – 19:30 SOUPER / DINNER
19:45
Mot de bienvenue et orientation / Welcome and orientation
20 :00 – 21:00 CONFÉRENCE PLÉNIÈRE / KEYNOTE LECTURE
Présentateur / Chair: Marie Kmita
Claudio STERN, UCL, London, UK
Twinning: the ultimate regeneration
21:00
SOIRÉE DE BIENVENUE / GET-TOGETHER WELCOME PARTY
MARDI / TUESDAY, MARCH 18 MARS
7:00 – 8:30
PETIT-DÉJEUNER / BREAKFAST
8:30 – 11:30 SESSION 1 – MORPHOGENESIS I
Présentateur / Chair: Sarah Jenna
8:30 – 9:00
Licia Selleri – Cornell University, NY, USA
Shaping Craniofacial and Limb Morphogenesis with ESCRTs
9:00 – 9:30
CC Hui – Sick Kids, Toronto, CA
Hedgehog signaling in development and disease
9:30 – 9:45
Brian Ciruna - The Hospital for Sick Children, Toronto, CA
Analysis of ptk7 mutant zebrafish demonstrates a genetic link between
idiopathic and congenital scoliosis, and implicates dysregulated Wnt
signaling in the pathogenesis of human disease
9:45 – 10:00
Noumeira Hamoud – IRCM, Montreal, CA
The G-protein coupled receptor BAI3 promotes myoblast
fusion in Vertebrates.
10:00 – 10:30 PAUSE / BREAK
10:30 – 10:45 Pamela Hoodless – Terry Fox Laboratory, Vancouver, CA
A regulatory network controls Nephrocan expression and midgut
patterning
10:45 – 11:15 Thomas Lecuit – IDBM, Marseilles, FR
Regulation of cell mechanics during tissue morphogenesis
11:15 – 11:45 Guy Tanenzapf – UBC, Vancouver, CA
Cell-matrix adhesion and morphogenesis: A systems biology approach
12:00 – 13:30 DINER / LUNCH
13:30- 15:00 PAUSE / BREAK
15:00 – 16:00 Workshop: Richard Rachubinski - Phil Hieter
Rare Diseases Research Catalyst Network Funding Opportunity
16:00 – 17:00 Meet and greet reception – Institute of Genetics, CIHR
2
16:30 – 18:30 SESSION A / POSTER SESSION A
18:30 – 20:00 SOUPER / DINNER
20:00 – 22:00 SESSION 2 – CELL DIVISION AND POLARITY
Présentateur / Chair: Martin Simard
20:00 – 20:30 Yohanns Bellaïche – Institut Curie Paris, FR
Epithelial cell dynamics
20:30 – 21:00 Monique Zetka – McGill University, Montréal, CA
Meiosis in C. elegans
21:00 – 21:15 Carine Monat-reliat – IRCM, Montreal, CA
SAPCD2, a novel Gαi-interacting protein, regulates mitotic spindle
orientation and asymmetric cell divisions in the developing retina
21:15 – 21:30 Sevan Hopyan - The Hospital for Sick Children, Toronto, CA
Anisotropic stress orients remodelling of mammalian limb bud ectoderm
21:30 – 22:00 Gregory Emery – IRIC, Montréal, CA
Cell-cell coordination during collective cell migration
22:00
RAFRAICHISSEMENTS / SOCIAL HOUR
MERCREDI / WEDNESDAY, MARCH 19 MARS
7:00 – 8:30
PETIT- DÉJEUNER / BREAKFAST
8 :30 – 11 :30 SESSION 3 – NEURO-DEVELOPPEMENT
Présentateur / Chair: Julie Lefevbre
8:30 – 9:00
Hideto Takahashi – IRCM, Montréal, CA
Trans-neuronal mechanisms for inducing central synapse development
9:00 – 9:15
Moloud Ahmadi – McGill University, Montréal, CA
AMPK is expressed in specific neurons to trigger adaptive behaviors in
response to nutrient stress.
9:15 – 9:45
Douglas Allan – UBC, Vancouver, CA
Identification and functional testing of BMP-dependent enhancers in
Drosophila neurons
9:45 – 10:15
Mei Zhen – Samuel Lunenfeld Institute, Toronto, CA
C. Elegans motor circuit: development, function and disease modeling
10:15 – 10:45 PAUSE / BREAK
10:45 – 11:15 Brian Link – MCW, Wisconsin, US
Analysis of hippo pathway signaling during ocular development in Zebrafish
11:15 – 11:45 Armen Saghatelyan – Université Laval, Québec, CA
Neuronal migration in the adult brain
11:45 – 12:00 Angelo Iulianella - Dalhousie University, Halifax, CA
Embryonic neural patterning in the absence of a Shh gradient
12:00 – 12:45 Workshop: CIHR reforms. Modus operandi for applicants.
Jennifer O’Donoughue (Executive Director, Reforms Implementation)
12:45 – 14:15 DINER / LUNCH
3
14:15 - 16:00 PAUSE / BREAK
16:00 – 18:00 SESSION B / POSTER SESSION B
18:00 – 20:30 SESSION 4 – STEM CELLS / EPIGENETICS / REPROGRAMMING
Présentateur / Chair: Richard Roy
18:00 – 18:30 Vincent Tropepe – U. Toronto, CA
Npat-dependent post-transcriptional regulation of core histone
genes is required for the maintenance of a retinal progenitor cell
fate
18:30 – 19:00 Fabio Rossi – UBC, Vancouver, CA
Interactions between MSCs and monocytes/macrophages in tissue
regeneration and degeneration
19:00 – 19:15 Katie Cockburn - The Hospital for Sick Children, Toronto, CA
The Hippo pathway member Nf2 is required for inner cell mass
specification
19:15 – 19:30
Julie Claycomb – University of Toronto, CA
The C. elegans Argonaute CSR-1 Licenses Germline Gene Expression
19:30 – 20:00 Steve Bilodeau – University Laval, Québec, CA
Controlling the tissue-specific gene expression program
20:30– 23:00 BANQUET /GALA DINNER
“Tire sur la neige”/ “Taffy on snow”
JEUDI / THURSDAY, MARCH 20 MARS
7:00 – 9:00
PETIT-DÉJEUNER / BREAKFAST
9:00 – 12:00 SESSION 5 – MORPHOGENESIS 2
Présentateur / Chair: Maxime Bouchard
9:00 – 9:30
Sarah Childs – University of Calgary, Alberta, CA
Vascular development in Zebrafish
9:30 – 10:00
David Hipfner – IRCM, Montréal, CA
Complexities of G-protein-coupled receptor kinase function in
hedgehog signaling
10:00 – 10:15 Konstantin Khetchoumian, IRCM, Montreal, CA
Molecular mechanisms for building a secretory cell
10:15 – 10:45 PAUSE / BREAK
10:45 – 11:00 Stéphanie Almeida - Samuel Lunenfeld Institute, Toronto, CA
The linear ubiquitin-specific deubiquitinase Gumby/Fam105b regulates
angiogenesis
11:00 – 11:30 Christian Hardtke – University of Lausanne, CH, Switzerland
Molecular genetic control of root system development - from the wild to
the lab and back again
11:30 – 12:15 Nipam H. Patel – University of California, Berkeley, US
The evolution of developmental diversity: Insights from emerging
model systems
12:15 – 12h20 Mot de cloture / Closing Remark
12:20
DINER/LUNCH – DÉPART/DEPARTURE
4
7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
ONGLET 1
Conférenciers / Speakers
Oral presentations
5 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
CONFÉRENCE PLÉNIÈRE / KEYNOTE LECTURE
Claudio STERN, UCL, London, UK
Twinning: the ultimate regeneration
Claudio D. Stern, Angela Torlopp, Mohsin Khan and Federica Bertocchini
Department of Cell & Developmental Biology, University College London
Gastrulation has been said to be "the most important event in your life" (Lewis
Wolpert c. 1980) because it is during this time that the three main layers of
cells are set up and that the body axis is established, and when many cells first
become committed to their fates. Until the start of gastrulation, amniote
embryos can still give rise either to a single or to multiple individuals (twins).
This reveals not only "pluripotency" of fates, but an even more striking
potential of the embryo to self-organize into a complete organism. This can be
viewed as an extreme case of regeneration: parts of the embryo can
regenerate the entire body and form another individual. But then, what
mechanisms prevent this during normal development? We will review some
recent progress in understanding the molecular and cellular mechanisms that
coordinate fate, polarity and pattern in the embryo and which also regulate
twinning.
6 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Licia Selleri - Cornell University
Shaping Craniofacial and Limb Morphogenesis with ESCRTs
Jennifer Feenstra, Karen Handschuh, Matthew Koss, Elisabetta Ferretti, Rediet
Zewdu, John Manak, Michael Depew, Kathryn Anderson, Elizabeth Lacy, and
Licia Selleri
Sorting and degradation of receptors and associated signaling molecules
maintain homeostasis of conserved signaling pathways during cell specification
and tissue development. Yet, whether machineries that sort signaling proteins
act on different receptors and ligands in different contexts remains poorly
understood. Here we show that Vacuolar protein sorting 25, Vps25, a
component of ESCRT-II (Endosomal Sorting Complex Required for Transport II),
directs selective endosome-mediated modulation of FGF signaling in limbs. By
ENU-induced mutagenesis we isolated a mouse line with striking craniofacial
defects and polydactyly. We revealed that this line carries a hypomorphic
mutation of Vps25 (Vps25ENU). Unlike Vps25-null embryos we generated,
Vps25ENU/ENU mutants survive until late gestation. Their limbs display FGF
signaling enhancement and consequent hyper-activation of the FGF-SHH feedback loop causing polydactyly. Unexpectedly, early WNT and BMP signaling
remain unperturbed in Vps25ENU/ENU mutant limb buds. Notably, Vps25ENU/ENU
Mouse Embryonic Fibroblasts (MEFs) exhibit engorged multivesicular bodies
(MVBs) and aberrant FGFR trafficking and degradation. However, in
Vps25ENU/ENU MEFs SHH signaling is unperturbed. These studies establish that the
ESCRT-II machinery selectively limits FGF signaling in distinct vertebrate
patterning processes.
7 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Chi Chung Hui - The Hospital for Sick Children
Positive and negative regulation of limb patterning by Sonic hedgehog (Shh)
signalling
Olena Zhulyn, Danyi Li, Rui Sakuma, Niki Alizadeh Vakili, Rong Mo, Vijitha
Puviindran, Xiaoyun Zhang, Sevan Hopyan, and Chi-Chung Hui
Program in Developmental & Stem Cell Biology, The Hospital for Sick Children
and Department of Molecular Genetics, University of Toronto
Patterning and growth of the embryonic vertebrate limb is dependent on Shh.
Shh expression is not observed during the first 12h of limb development. During
this phase, the limb bud is pre-patterned into anterior and posterior regions
through the antagonistic actions of transcription factors Gli3 and Hand2. Shh
regulates the identities of posterior limb elements, including the ulna/fibula
and digits 2 through 5, whereas anterior and proximal structures (the
humerus/femur, radius/tibia and digit 1) are regarded as Shh-independent. In
this talk, I will present data showing that patterning of the proximal and
anterior limb skeleton involves two phases. Irx3 and Irx5 (Irx3/5) are essential
in the initiating limb bud to specify progenitors of the femur, tibia and digit 1.
Intriguingly, these elements are restored in Irx3/5 null mice when Shh signaling
is diminished, indicating that Shh negatively regulates their formation after
initiation. Our data provide genetic evidence that support the concept of early
specification and progressive determination of anterior limb pattern.
Furthermore, we found that precocious activation of Shh signaling compromises
the formation of these anterior progenitors and affects the establishment of
signaling centers as well as limb outgrowth.
8 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Thomas Lecuit – Institut de biologie du développement de Marseilles
Biomechanical control of tissue shape changes
Thomas Lecuit
Epithelial tissues exhibit a remarkable dual property of robustness and fluidity.
This operates on different time scales and relies on unique mechanical
properties of the cell cortex and on adhesive interactions between cells. We
seek to understand the fundamental molecular mechanisms responsible for this
property. This is essential to understand morphogenesis of developing embryos
and organs, and is severely affected in a number of disease, in particular
cancer progression.
To that end we develop a range of approaches, from the genetic and
pharmacological perturbations of molecular components, the quantitative
imaging of proteins using a variety of photonic methods, probing of the physical
properties of cells within intact tissues, and computational modelling of
morphogenesis at different scales (molecular to tissue scales).
I will present our recent progress in understanding how adhesion and cortical
tension regulate the dynamic remodelling of cell contacts in the primary
epithelium of Drosophila embryos. I will first focus on the regulation of tensile
activity driving cell shape changes. I will also address how E-cadherin-actin
interactions control force transmission at cell interfaces.
Last I will address how biochemical signals control the spatial patterns of
actomyosin contractility.
9 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Guy Tanentzapf - University of British Columbia
Cell-matrix adhesion and morphogenesis: A systems biology approach
Stephanie J. Ellis1, Emily E. Lostchuck1, Guðlaug Katrín Hákonardóttir1, Katie
Goodwin1, Michael J. Fairchild1, Pablo C. Lopez1, Raibatak Das2,3, Dan Coombs2,
James J. Feng2, Guy Tanentzapf1.
1
Department of Cellular and Physiological Sciences, University of British
Columbia, Vancouver, British Columbia.
2
Department of Mathematics and Institute of Applied Mathematics, University
of British Columbia, Vancouver, British Columbia.
3
Department of Integrative Biology, University of Colorado Denver, Denver,
Colorado, USA.
Our lab is interested in how complex tissue architecture arises during animal
development through the process of morphogenesis. Our primary focus is on
Cell adhesion to the ExtraCellular Matrix (ECM), which has numerous roles
during development. Cell-ECM adhesion is largely mediated by the integrin
family of adhesion receptors. We wish to elucidate how integrins mediate a
vast diversity of roles during development. To address this question we are
using a cross-disciplinary systems-level approach. We start by deriving
knowledge from structural and single molecule biophysical studies of integrin
and its associated proteins. This knowledge is then applied, using molecular
and transgenic approaches, to alter the regulation and mechanical properties
of integrin-mediated adhesion on the level of the cell. Using localization
studies, FRAP, and other quantitative imaging approaches, combined with
mathematical modeling we analyze the regulation of the assembly and stability
of the adhesion complex. Information from cell-level studies is then used to
study tissue level functions of integrin. Using live imaging combined with
mathematical modeling we can analyze the mechanical properties of tissues
undergoing morphogenesis. By integrating these levels of analysis, from
molecule to cell to tissue, we are uncovering the fundamental mechanisms that
regulate Cell-ECM adhesion during development.
10 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Yohanns Bellaiche - Institut Curie - Centre de recherche
Coupling cytokinesis and adherens junction formation in epithelial
Tissue
S.Herszterg, D. Pinheiro, A. Leibfried, F. Bosveld, C. Martin and Y. Bellaiche
Cell division in epithelial tissues requires the formation of new adherens
junctions (AJ) to maintain tissue polarity, integrity and architecture. How
cytokinesis is coupled to AJ formation has remained unexplored. We show that
cytokinesis in epithelial tissue relies on an interplay between the dividing cell
and its neighbors. During cytokinetic ring constriction, the membranes of the
dividing cell and its neighbors co-ingress, creating a topological obstacle to AJ
formation between the two daughter cells. In response to ring constriction, the
neighboring cells locally accumulate Myosin II and produce the cortical tension
necessary to set the initial geometry of the daughter cell interface. The new
interface is further stabilized by Arp2/3-dependent actin polymerization, which
is spatially and temporally controlled by midbody formation in the dividing cell.
Actin polymerization allows the removal of the neighboring membranes from
the space in between the daughter cells, thereby regulating AJ final length and
the epithelial cell arrangement upon division. We propose that cytokinesis in
epithelia is a multicellular process, whereby the cooperative actions of the
dividing cell and its neighbors define a two-tiered mechanism that spatially and
temporally couples cytokinesis and AJ formation, while maintaining tissue
cohesiveness.
11 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Monique Zetka - McGill University
Meiotic chromosome dynamics during homologue pairing in C. elegans
Sara Labella, Anja Boskovic, and Monique Zetka
Department of Biology, McGill University, Montréal, QC, H3A 1B1
The pairing of homologous chromosomes at the onset of meiotic prophase is the
essential prerequisite to the formation of crossovers that will direct homologue
segregation at the first division. A conserved feature of early prophase is the
attachment of telomeres to the nuclear envelope (NE) and their linkage to
cytoskeletal forces that drive chromosome motion during the pairing process.
In C. elegans, specialized regions known as pairing centres (PCs) associate with
the NE and establish linkages to the microtubule cytoskeleton via SUN/KASH
domain protein bridges that span the intact NE. Our previous work has shown
that polo-kinase 2 (PLK-2) localizes to the PCs and is required there for meiotic
chromosome pairing and reorganization of the NE to concentrate SUN/KASH
domain membrane proteins in the vicinity. Using wild-type and mutant variants
of PLK-2-tagged with mCherry to assess meiotic chromosome dynamics in living
animals, we have investigated the role of PLK-2, NE reorganization, and
chromosome motion in facilitating homologous chromosome pairing.
12 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Gregory Emery - Institut de recherche en immunologie et en cancérologie
Cell-cell coordination during collective cell migration
Collective cell movements contribute to development and metastasis. The
small GTPase Rac is a key regulator of actin dynamics and cell migration but
the mechanisms that restrict Rac activation and localization in a group of
collectively migrating cells are unknown. Here, we demonstrate that the small
GTPases Rab5 and Rab11 regulate Rac activity and polarization during
collective cell migration. We use photoactivatable forms of Rac to demonstrate
that Rab11 acts on the entire group to ensure that Rac activity is properly
restricted to the leading cell through regulation of cell-cell communication. In
addition, we show that Rab11 binds to the actin cytoskeleton regulator Moesin
and regulates its activation in vivo during migration. Accordingly, reducing the
level of Moesin activity also affects cell-cell communication, whereas
expressing active Moesin rescues loss of Rab11 function. Our model suggests
that Rab11 controls the sensing of the relative levels of Rac activity in a group
of cells, leading to the organization of individual cells in a coherent
multicellular motile structure.
13 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Hideto Takahashi - Institut de recherches cliniques de Montréal (IRCM)
Trans-neuronal mechanisms for inducing central synapse development
Hideto Takahashi
Institut de recherches cliniques de Montreal (IRCM), 110 avenue des Pins Ouest,
Montréal, QC, Canada, H2W 1R7
Synapse development requires not only physical contact between axons and
target neurons but also chemically matched pre- and post-synaptic
differentiation. Thus, synaptic organizing complexes, trans-neuronal adhesion
complexes with the ability to induce pre- and/or post-synaptic differentiation,
have been suggested to function as essential molecular signals for synapse
development. The neuroligin-neurexin complex has been the most notable
synaptic organizing complex and a genetic determinant predisposing to autism.
However, synapse diversity suggests many other synaptic organizing complexes
for excitatory and/or inhibitory synapses. To identify novel synaptic organizers
that induce presynaptic differentiation, we performed a functional expression
screen based on a neuron-fibroblast coculture assay combined with full-length
cDNA library or candidate prediction. Further, to identify their presynaptic
receptor, we performed candidate cDNA screening based on a cell-surface
binding assay using soluble Fc-fusion ectodomain proteins of the synaptic
organizers. Using these two screening approaches, we demonstrated that TrkCPTPσ trans-synaptic complex functions as a bidirectional synaptic organizing
complex that selectively regulates excitatory synapse development. We further
identified Slitrk3-PTPδ trans-synaptic complex as an inhibitory synapse-specific
synaptic organizing complex. Given genetic linkages of our identified molecules
with neuropsychiatric disorders, our data suggest that aberrant synaptic
organization could be a common pathogenesis of many neuropsychiatric
disorders.
14 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Douglas, Allan - University of British Columbia
Identification and functional testing of BMP-dependent enhancers in
Drosophila neurons
Berndt AJ1*, Vuilleumier R1*, Ridyard MS1, Lian T1, Pyrowolakis G2, Allan DW1.
1
Department of Cellular and Physiological Sciences, 2420 Life Sciences
Institute, University of British Columbia. Vancouver
2
Institute for Biology I, Albert Ludwigs University of Freiburg, Freiburg,
Germany. *co-first authors
Developing neurons often require retrograde signals from the target cells they
innervate to terminally differentiate and attain mature morphological and
synaptic properties. Bone morphogenetic proteins (BMPs) act as target-derived
signals that direct terminal differentiation, synaptic growth and
neurotransmission in fly and vertebrate neurons. The neural function of BMP
signaling is largely mediated through gene regulation, carried out by the Smad
transcriptional effectors, however the target genes and their transcriptional
regulation are largely unknown. We are examining the mechanisms underlying
BMP-driven Smad transcriptional activity in the nervous system. We have
defined the cis-regulatory architecture of BMP-dependent FMRFa gene
expression and identified its novel BMP-response element (BMP-RE) sequence.
Analysis of cofactor activity at this BMP-RE shows that the nervous system
utilizes a non-canonical mechanism for target gene activation. Further, we
identified putative BMP-RE sequences through the genome and we find many of
these to be functionally active in the nervous system and to pinpoint the
adjacent novel BMP-dependent genes.
15 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Mei Zhen - University of Toronto
The development and operation of the C. elegans motor circuit
Mei Zhen
Lunenfeld-Tanenbaum Research Institute, Department of Molecular Genetics,
University of Toronto
We aim to address a basic question: how a developing nervous system regulates
animal behaviors like locomotion throughout life. To continuously drive and
organize movements of the newborn and adult, life stages that might differ
significantly in anatomic organization and in size, any nervous system must
develop as a coordinated dynamic and structural entity within a changing body
plan. In collboration with the Samuel and Litchman groups, we are mapping the
anatomic and functional development of the motor circuit at synaptic
resolution in the nematode C. elegans across development. In parallel, using
optical neurophysiology and optogenetics, we address how motor circuit
activities are coordinated to drive the sinodosidual locomotory behavior at
different developmental stages.
16 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Brian Link - Medical College of Wisconsin
Analysis of Hippo-Yap/Taz-Tead signaling in ocular development:
insights to Sveinsson Chorioretinal Atrophy
Joel B. Miesfeld and Brian A. Link
Dept. of Cell Biology and Neurobiology, Medical College of Wisconsin,
Milwaukee WI.
Sveinsson chorioretinal atrophy (SCRA) is a congenital defect that results in loss
of the retinal pigmented epithelium (RPE), and degeneration of retinal
photoreceptors and choroid. Loss of RPE primarily affects regions radiating
from the optic disc and therefore affects macular-based, high acuity vision.
SCRA is caused by a mutation in the Yap/Taz binding domain of the
transcription factor Tead1. Yap, and its homolog Taz, are transcriptional coactivators and function downstream target of the Hippo signaling module. To
investigate the mechanisms of this disorder we have generated a suite of
transgenic and mutant tools to monitor, manipulate, and delete components of
the Hippo-Yap/Taz-Tead pathway. Overall, our data suggest that yap/taz
activity may be both necessary and sufficient to drive RPE genesis from eye
field progenitor cells and suggests altered cell fate regulation underlies the RPE
deficits of Sveinsson Chorioretinal Atrophy. Funding: R01EY014167 (BAL).
17 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Armen Saghatelyan - Université Laval
The mechanisms of neuronal migration in the adult brain
Armen Saghatelyan
Université Laval
The adult mammalian forebrain retains the remarkable capacity to produce
new neurons throughout its entire life span. Neuronal precursors are generated
in the subventricular zone (SVZ) and migrate in chains, along the rostral
migratory stream (RMS), towards the olfactory bulb (OB). How can these
neuronal precursors migrate such a long distance, what keeps them in the
migratory pathway, and what allows some neuronal precursors to successfully
accomplish their migration while others die?
We first demonstrate that adult neuronal precursors are guided towards and
into OB by blood vessels that topographically outline the RMS and serve as a
physical scaffold for migrating neuroblasts. Blood vessels also provide
molecular cues that guide neuronal precursors in the adult RMS. The
vasculature-mediated migration of neuronal precursors is re-activated in the
injured brain to recruit neuroblasts into the post-stroke striatum.
We also show that autophagy, a self-catabolic pathway involved in intracellular
bulk degradation and recycling, is very active in migrating neuroblasts and that
Atg5 (autophagy-related 5) conditional deletion decreases the neuronal
migration and is critical for the survival of newborn cells.
Altogether, these data reveal the roles of vasculature and autophagy in the
migration of neuronal precursors in the adult brain.
18 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Vincent Tropepe - University of Toronto
Npat-dependent post-transcriptional regulation of core histone genes
is required for the maintenance of a retinal progenitor cell fate
Michael Mattocks1, Maria Augusta Sartori da Silva1, Monica Dixon-Fox1, Jason
Willer2, Ronald Gregg2, and Vincent Tropepe1
1
2
Department of Cell & Systems Biology, University of Toronto, Canada;
Department of Biochemistry & Molecular Biology, University of Louisville, USA
Retinal progenitor cells (RPCs) contribute to the postembryonic growth of the
vertebrate retina. In fish, RPC neurogenesis localized to the ciliary marginal
zone (CMZ) continues throughout life. Yet, very little is known about the
postembryonic maintenance of this niche. A forward genetic screen for
identifying novel genes that control CMZ function revealed the rys mutant,
which in early postembryonic stages displays an enlarged CMZ that is
progressively disorganized with morphologically abnormal cells. We found that
the mutated gene in rys encodes the nuclear protein at the ataxia
telangiectasia locus (npat) on chromosome 15. Mammalian Npat is activated in
a cell cycle dependent manner and in vitro studies suggest that its major
function is to coordinate the transcription of core histone genes during the
G1/S phase transition. The predicted zebrafish mutant npat protein deletes a
C-terminus domain required for cell cycle progression, but retains the domains
required for the transcriptional activation of histone genes. Mutant RPCs
display cell cycle defects and are incapable of generating differentiated retinal
cells leading to a retinal growth defect. Unexpectedly, core histone transcripts
are significantly increased in rys mutants, and unlike in wild type cells these
transcripts are polyadenylated. Our findings highlight the importance of npatdependent post-transcriptional regulation during the in vivo coupling of cell
cycle and histone expression as a requirement for maintaining RPC fate.
19 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Fabio Rossi – UBC, Vancouver, CA
Interactions between MSCs and monocytes/macrophages in tissue
regeneration and degeneration
20 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Steve Bilodeau - Université Laval
Controlling the tissue-specific gene expression program
Steve Bilodeau
Like computers, our cells depend on operating systems to drive normal
functions. The gene expression programs are the source code our cells rely on
to play their biological functions while corrupted programs trigger diseases.
Each individual gene is accessed following a precise number of commands that
need to be executed in an orderly fashion. Individual cells must therefore
integrate the information provided by various transcription factors and
cofactors to maintain the tissue-specific chromatin and chromosome
architectures essential to control the gene expression program.
Embryonic stem cells (ESCs) represent a great model system to study rules
controlling the gene expression program during normal and disease
development. Using a genomic and bioinformatic approaches, we are
investigating the molecular determinants of the ESC gene expression program.
More specifically, we are comparing the transcriptional rules associated with
tissue-specific versus constitutive gene expression. Most transcriptional rules
discovered in ESCs are applicable to all cell types. These results allow us to
revisit the transcriptional consequences of various gain- and loss-of-function of
transcriptional regulators in a variety of diseases ranging from developmental
syndromes to cancers.
21 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Sarah Childs - University of Calgary
Vascular mural cell development in Zebrafish
Corey R. Arnold, Tom R. Whitesell, Peter J. Spice, Jae-Ryeon Ryu and Sarah J.
Childs
Alberta Children's Hospital Research Institute, University of Calgary.
Hemorrhagic stroke is the most common type of pediatric stroke and often
arises from vascular malformations. During development, blood vessels arise
from naked endothelial cell tubes that are progressively covered by vascular
mural cells, either smooth muscle cells or pericytes. We have characterized
normal mural cell development using in vivo imaging, transmission electron
microscopy and mutant analysis. A screen for genes downregulated in models
of embryonic hemorrhage suggested that two transcription factors FoxF2b and
Bapx1 were involved in vascular stabilization. We show that these genes
promote interactions between mural cells and endothelium. We observe fewer
endothelial-perivascular cell contacts at the time of hemorrhage, and
decreased smooth muscle marker expression. The transcriptional targets of
these factors are unknown but preliminary experiments suggest that PDGFR-α is
downregulated with loss of nkx3.2. We are currently investigating the
mechanism utilized by these two transcription factors to understand this
otherwise poorly characterized developmental process.
22 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
David Hipfner - Institut de recherches cliniques de Montréal (IRCM)
Complexities of G-protein-coupled receptor kinase function in
Hedgehog signaling
David R. Hipfner1,2,3, Dominic Maier1,2, Shuofei Cheng1,2, and Denis Faubert1,4.
1
IRCM, 110 Pine Avenue West, Montréal, QC, H2W 1R7, Canada;
Department of Anatomy & Cell Biology, McGill University, Montréal, QC;
3
Department of Medicine, Université de Montréal, Montréal, QC;
4
Proteomics Core Facility, IRCM.
2
Hedgehog (Hh) signaling is essential for normal growth and patterning of
embryonic tissues. Cytoplasmic signaling is activated by multisite
phosphorylation of the transmembrane protein Smoothened (Smo) in its
cytoplasmic C-terminus. Aside from a short membrane-proximal stretch, the
sequence of the C-terminus is highly divergent in different phyla, and the
mechanism of Smo activation and transduction of the signal to downstream
effectors also differs. To clarify the conserved role of G-protein-coupled
receptor kinases (GRKs) in Smo regulation, we mapped four clusters of GRK
phosphorylation sites in the membrane-proximal C-terminus of Drosophila Smo.
Phosphorylation at these sites enhances Smo dimerization and increases but is
not essential for Smo activity. Three of these clusters overlap with regulatory
phosphorylation sites in mouse Smo and are highly conserved throughout the
bilaterian lineages, suggesting that they serve a common function. Consistent
with this, a C-terminally truncated form of Drosophila Smo consisting of just
the highly conserved core can recruit the downstream effector Costal-2 and
activate target gene expression, in a GRK-dependent manner. We conclude
that GRK phosphorylation of the membrane proximal C-terminus is an
evolutionarily ancient mechanism of Smo regulation, and that the regulatory
and signaling mechanisms of bilaterian Smo proteins are more similar than has
previously been recognized.
23 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Christian Hardtke – Lausanne University
Molecular genetic control of root system development - from the wild
to the lab and back again
Christian S. Hardtke
Department of Plant Molecular Biology, University of Lausanne, Biophore
Building, CH-1015 Lausanne, Switzerland
Root system architecture is pivotal for plant performance and shaped by
environmental as well as endogenous factors. Natural genetic variation for root
system architecture traits exists, but only few causal loci are known. Among
them, loss-of-function alleles of the Arabidopsis BREVIS RADIX (BRX) gene
confer reduced primary root growth, leading to an overall more compact root
system. Surprisingly, this can be traced to impaired differentiation of the
protophloem, the vascular tissue that delivers metabolites and developmental
signals to the root meristem. Second site suppressor screening in brx mutants
led to the discovery of a molecular genetic framework for protophloem sieve
element specification, which is a pre-requisite for overall protophloem pole
formation. The data suggest that sieve element differentiation is determined
by BRX-dependent balance between the opposing activities of a peptide ligandreceptor-like kinase signaling pathway on one side and a master regulator of
phloem fate on the other. Stochastic hyperactivity of the peptide-signaling
pathway is responsible for the developmental defects in brx root meristems.
Interestingly, these local defects have important systemic consequences,
including plasma membrane proton pump hyperactivity. This in turn confers
root system adaptation to acidic soil, explaining why brx loss-of-function
mutants can be found in such conditions in nature.
24 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Nipam H. Patel - Berkeley University
The evolution of developmental diversity: Insights from emerging
model systems
Dept. Molecular Cell Biology, 519A LSA #3200, Berkeley, CA 94720-3200
Studies in model species have revealed many of the genetic networks that
guide development, and have opened the door to understanding how
evolutionary changes in these networks lead to morphological and
developmental diversity. I will describe our recent studies to understand
developmental variation, focusing on the germline in the crustacean, Parhyale
hawaiensis, and structural coloration in butterflies. Parhyale derives its
primordial germ cells from a single precursor cell at the eight-cell stage. If this
cell is ablated, the animal hatches without a detectable germline, but
remarkably these animals are fertile as adults. We have been able to
determine the source and timing of this replacement. I will also describe the
developmental basis of structural coloration in the Achillides swallowtails. The
scales of these butterflies use a combination of multilayer reflection and scale
geometry to create a range of colors. Developmentally, the scale geometry
appears to be controlled by cytoskeletal reorganization, and evolutionary
changes in geometry appear to contribute to variation between species,
between populations, and between seasonal variants.
25 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
RÉSUMÉS CHOISIS POUR PRÉSENTATION ORALE
(ordre de présentation)
ABSTRACTS SELECTED FOR ORAL PRESENTATION
(order of presentation)
Brian Ciruna - The Hospital for Sick Children, Toronto
Analysis of ptk7 mutant zebrafish demonstrates a genetic link
between idiopathic and congenital scoliosis, and implicates
dysregulated Wnt signaling in the pathogenesis of human disease
Noumeira Hamoud – IRCM, Montréal
The G-protein coupled receptor BAI3 promotes myoblast
fusion in Vertebrates
Pamela Hoodless – Terry Fox Laboratory, Vancouver
A regulatory network controls Nephrocan expression and midgut
patterning
Carine Monat-Reliat – IRCM, Montréal
SAPCD2, a novel Gαi-interacting protein, regulates mitotic spindle
orientation and asymmetric cell divisions in the developing retina
Sevan Hopyan - The Hospital for Sick Children, Toronto
Anisotropic stress orients remodelling of mammalian limb bud
ectoderm
Moloud Ahmadi – McGill University, Montréal
AMPK is expressed in specific neurons to trigger adaptive behaviors in
response to nutrient stress
Angelo Iulianella - Dalhousie University, Halifax
Embryonic neural patterning in the absence of a Shh gradient
Katie Cockburn - The Hospital for Sick Children, Toronto
The Hippo pathway member Nf2 is required for inner cell mass
specification
Julie Claycomb – University of Toronto
The C. elegans Argonaute CSR-1 Licenses Germline Gene Expression
Konstantin Khetchoumian, IRCM, Montréal
Molecular mechanisms for building a secretory cell
Stéphanie Almeida - Samuel Lunenfeld Institute, Toronto
The linear ubiquitin-specific deubiquitinase Gumby/Fam105b regulates
26 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
angiogenesis
Analysis of ptk7 mutant zebrafish demonstrates a genetic link between
idiopathic and congenital scoliosis, and implicates dysregulated Wnt
signaling in the pathogenesis of human disease
Brian Ciruna
Program in Developmental & Stem Cell Biology, The Hospital for Sick Children,
Toronto, Ontario, Canada, M5G 1X8
Department of Molecular Genetics, The University of Toronto, Toronto,
Ontario, Canada, M5S 1A8
Scoliosis is a complex genetic disorder of the musculoskeletal system,
characterized by three-dimensional rotation of the spine. Curvatures caused by
malformed vertebrae (congenital scoliosis/CS) are apparent at birth. However,
spinal curvatures with no underlying vertebral abnormality (idiopathic
scoliosis/IS) are far more prevalent, and most commonly manifest during
adolescence. Despite intense research, the genetic and biological mechanisms
underlying IS remain poorly understood due largely to a lack of suitable
experimental models. Here we describe zygotic ptk7 mutant zebrafish,
deficient in a critical regulator of Wnt signaling, as the first genetically defined
animal model of IS. We identify a rare sequence variant from human IS patients
that disrupts PTK7 function, supporting a role for dysregulated Wnt activity in
the pathogenesis of disease. Furthermore, we demonstrate that early loss-offunction, maternal-zygotic ptk7 mutants (MZptk7) display vertebral anomalies
consistent with congenital scoliosis, suggesting that CS and IS may share
common genetic mechanisms.
27 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
THE G-PROTEIN COUPLED RECEPTOR BAI3 PROMOTES MYOBLAST FUSION IN
VERTEBRATES
Hamoud N1,Tran V 1, Croteau LP1, Kania A1 and Côté JF1. 1IRCM
1
Institut de recherches cliniques de Montréal (IRCM), Montréal, QC, Canada
H2W 1R7
Myoblast fusion is a decisive process in myogenesis. Studies in Drosophila
revealed an important role for cytoskeleton in membrane fusion. Previous work
in mice, showed the importance of the GEF DOCK1 and Rac underlining the
evolutionary conserved machinery between Drosophila and mammals during
myoblast fusion mechanism. However, receptors that integrate extracellular
signal able to activate Rac pathway are still unknown in mammals. In this study
we describe the GPCR BAI3 as a signal transductor via its ability to engage the
ELMO/DOCK/Rac pathway. Knockdown of both ELMO2 and BAI3 strongly
inhibited myoblast fusion in cell lines models. Mechanistically, re-expression of
BAI3 is able to rescue the fusion defect, but a BAI3 mutant that fails to interact
with ELMO is unable to restore fusion. Since BAI3 is expressed in the chicken
embryos, we used this model to study the in vivo role of BAI3 by developing a
somite electroporation procedure. Expression of a BAI3 mutant unable to bind
ELMO, but not the WT receptor, completely blocks myoblast fusion in vivo.
These findings establish a myogenic role for BAI3 in activating the Rac pathway
and place this new GPCR as the first membrane receptor essential for myoblast
fusion.
28 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
A REGULATORY NETWORK CONTROLS NEPHROCAN EXPRESSION AND MIDGUT
PATTERNING
Juan Hou*1, Wei Wei*1, Ranajeet S. Saund2, Ping Xiang1, Thomas J.
Cunningham3,Daphne Y.D. Lu1, Joanne G. A. Savory4, Nicole A. J. Krentz1,
Rachel Montpetit1, Rebecca Cullum1, David Lohnes4, R. Keith Humphries1,5,
Gregg Duester3, Yukio Saijoh2, Pamela A. Hoodless1,6
1
Terry Fox Laboratory, BC Cancer Agency, Vancouver, BC, Canada
Dept of Neurobiology and Anatomy, University of Utah, Utah, USA
3
Development, Aging and Regeneration Program, Sanford-Burnham Medical
Research Institute, La Jolla, California 92037, USA
4
Cellular and Molecular Medicine, University of Ottawa, Ottawa, Canada
5
Experimental Medicine and6Dept of Medical Genetics, University of British
Columbia, Vancouver, BC, Canada
2
While many regulatory networks involved in defining definitive endoderm have
been identified, the mechanisms through which these networks interact to
pattern the endoderm are less well understood. To explore the mechanisms
involved in midgut patterning, we dissected the transcriptional regulatory
elements of Nephrocan (Nepn), the earliest known midgut specific gene in
mice. We observed that Nepn expression is dramatically reduced in Sox17-/- and
Raldh2-/-embryos compared to wild-type embryos. We further show that Nepn
is directly regulated by Sox17 and the retinoic acid receptor via two enhancer
elements located upstream of the gene. Moreover, Nepn expression is
modulated by Activin signaling with high levels inhibiting and low levels
enhancing RA-dependent expression. In FoxH1-/- embryos in which Nodal
signaling is reduced, the Nepn expression domain is expanded into the anterior
gut region suggesting that Nodal signaling can modulate expression in vivo.
Together, Sox17 is required for Nepn expression in the definitive endoderm,
while retinoic acid signaling restricts expression to the midgut region. A
balance of Nodal/Activin signaling regulates the anterior boundary of the
midgut expression domain.
*These authors contribute equally to this work
29 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
SAPCD2, a novel Gαi-interacting protein, regulates mitotic spindle
orientation and asymmetric cell divisions in the developing retina
Catherine Chiu 1 *, Carine Monat-Reliat 2,3 *, Mélanie Robitaille 1, Avais Daulat 1,
Michel Cayouette 2,3,4, #, and Stéphane Angers 1,5, #
1
Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy,
University of Toronto; 2 Cellular Neurobiology Research Unit, Institut de
recherches cliniques de Montréal; 3 Molecular Biology Program, Faculty of
Medicine, Université de Montréal; 4 Department of Anatomy and Cell Biology,
and Division of Experimental Medicine, McGill University; 5 Department of
Biochemistry, Faculty of Medicine, University of Toronto * Equal contribution; #
stephane.angers@utoronto.ca; michel.cayouette@ircm.qc.ca.
Asymmetric cell division (ACD) is a key process by which progenitors generate
cell diversity. The regulation of mitotic spindle orientation is critical for the
production of ACD. In both vertebrates and invertebrates, it is thought that
linking the Gαi/LGN/NuMa complex to the apical polarity complex
(Par3/Par6/aPKC) is essential for proper control of division orientation, but
how the activity of these complexes is regulated remains unclear. Using
proteomics in mammalian cells, we identified Sapcd2 as a novel interactor of
Gαi, LGN and Par3. In cultured MDCK cells, Sapcd2 is essential for proper
division orientation and cyst formation, by regulating cortical localization of
LGN. To explore the role of Sapcd2 in vivo, we used the developing mouse
retina as a model, where apico-basal divisions give rise to terminal ACDs
producing two neurons of different types. Sapcd2 knockout mice show a drastic
increase in apico-basal divisions and a concomitant increase in the proportion
of terminal ACDs generating two different types of neurons, at the expense of
terminal symmetric divisions generating two photoreceptors. Altogether, these
results identify Sapcd2 as a negative regulator of the Gαi/LGN/NuMa complex
involved in the control of spindle orientation and ACDs in the developing mouse
retina.
30 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Anisotropic stress orients remodelling of mammalian limb bud ectoderm
Kimberly Lau1*, Hirotaka Tao1*, Haijiao Liu2, Jun Wen2, Kendra Sturgeon1,
Natalie Sorfazlian1, Michael D. Wong3, Savo Lazic1,4, Danyi Li1,4, Steven
Deimling1, Ian Scott1,4, Brian Ciruna1,4, R. Mark Henkelman3, Trevor Williams5,
Anna-Katerina Hadjantonakis6, Rodrigo Fernandez-Gonzalez7, Yu Sun2, Sevan
Hopyan1,4,8
1
Program in Developmental and Stem Cell Biology, Research Institute, The
Hospital for Sick Children, Toronto, M5G 1X8, Canada
2
Department of Mechanical and Industrial Engineering, University of Toronto,
M5S 3G8, Canada
3
Mouse Imaging Centre, Hospital for Sick Children, Toronto Centre for
Phenogenomics,
Department of Biomedical Physics, University of Toronto, M5T3H7, Canada
4
Department of Molecular Genetics, University of Toronto, M5S 1A8, Canada
5
Program in Molecular Biology, School of Medicine, University of Colorado,
Aurora, CO, 80045, USA
6
Developmental Biology Program, Sloan-Kettering Institute, New York, NY
10065, USA
7
Institute of Biomaterials and Biomedical Engineering, University of Toronto,
Toronto, M5G 3G9, Canada
8
Division of Orthopaedic Surgery, Hospital for Sick Children and University of
Toronto, M5G 1X8, Canada
Physical forces that shape embryonic tissue are not well understood in vivo,
especially among later vertebrates. In the early limb bud, convergence of
ectoderm from dorsal and ventral sides forms the apical ectodermal ridge
(AER), though cellular and physical mechanisms underlying this process are
unclear. By live imaging wild type and conditional mutant mouse embryos, we
show that ectodermal remodelling involves complex cell rearrangements that
are conserved with modification relative to those of invertebrates. Using a
combination of theoretical finite element modelling as well as measurement
and manipulation of actual physical parameters in vivo by laser ablation and
atomic force microscopy, we show that mesodermal pressure and ectodermal
tension together orient ectodermal remodelling and shape the early bud in 3D.
Initial expansion of mesoderm anisotropically stresses ectoderm to polarise
cortical actin among AER progenitors, a process that requires Tcf/Lef
activation. Subsequent intercalation of AER progenitors generates a tensile
gradient that passively orients resolution of multicellular rosettes on adjacent
surfaces, a process facilitated by β-catenin-dependent attachment of cortex to
membrane. In the mouse limb bud therefore, key pathways transduce global
stress pattern to orient cell rearrangements that define tissue shape.
31 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
AMPK is expressed in specific neurons to trigger adaptive behaviors in
response to nutrient stress
Moloud Ahmadi and Richard Roy
Department of Biology, McGill University, 1205 avenue Docteur Penfield,
Montréal, QC, H3A 1B1
AMP-activated protein kinase (AMPK) is a metabolic sensor that has also
emerged as a modulator of behavioral response to food availability, although
the mechanisms by which this kinase affects such outcomes remain unclear.
Using a transgenic approach we observed that AMPK is expressed in a number
of neurons in larvae suggesting that AMPK may regulate neuronal function
during energy stress. We observed a locomotory defect in starved AMPKdeficient C. elegans larvae, which reveals their inability to appropriately
respond to nutrient stress. We monitored the expression of AAK-2 in key
neurons known to be involved in the various locomotory responses associated
with reduced food availability. Using a combination of genetics, optogenetics
and calcium imaging techniques, we discovered that although AMPK is not
required for essential aspects of neural function, it plays a key role in
regulation of neural activity during nutrient stress which in turn ensures
appropriate behavioral outcomes in response to this condition. Overall, our
study suggests that besides its well-known function in metabolic control, AMPK
acts as a molecular trigger required to elicit appropriate behavioral outputs in
response to nutrient/energy stress.
32 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Embryonic neural patterning in the absence of a Shh gradient
Angelo Iulianella1* and Paul Trainor2
1
Department of Medical Neuroscience, Faculty of Medicine, Dalhousie
University
Life Sciences Research Institute, 1348 Summer Street, Halifax, Nova Scotia,
Canada, B3H 4R2
2
Stowers Institute For Medical Research, 1000 E 50th Street, Kansas City, MO,
USA
The role of Sonic hedgehog signaling in vertebrate neural development is well
established. However, uncertainties remain concerning the mechanism of how
a signaling gradient is established and functions in growing tissues. The current
model of neural patterning emphasize a role for the length of time progenitor
cells are exposed to the morphogen Sonic Hedgehog (Shh) as the key
determinant in generating pattern in the vertebrate spinal cord. Although a Shh
concentration gradient is thought to pattern the neural tube, a temporal
mechanism implies that small amounts of morphogen are required to initiate
the diversification of ventral spinal cord cell types. We utilized a genetic
approach to test this idea during mouse spinal cord development. Because
Patched1 is both the receptor and negative regulator of Shh signaling, its
mutation sensitizes the embryo to Hedgehog signalling. We employed a novel
Patched1 mutation (called Wiggable) that removes its carboxyl-terminus, which
is required to inhibit Hedgehog signal transduction. We then tested whether
Wiggable mutants can rescue ventral patterning in situations where Shh levels
were either entirely absent or severely reduced. We accomplished this by using
the Shh-null and Hedgehog acteyltransferase (Hhat)-null mouse mutants,
respectively. Hhat encodes a palmitoylase that is required to produce secreted
forms of Hedgehog proteins, and is thus crucial for the establishment of the
Shh signaling gradient. In its absence, the spinal cord develops without the
ventral-most cell types, such as floorplate cells, V3 interneurons and
motoneurons. Surprisingly, Hhat/Wiggable double mutants show normal spinal
cord patterning, while Shh/Wiggable mutants lacked only floorplate cells. The
principal difference between Shh and Hhat mutants being that Hhat mutants
still have low amounts of Hedgehog signaling in the notochord. Thus, our
findings show that remarkably little Hedgehog signalling from the notochord is
all that is required to initiate the full range of neuronal identities in the
vertebrate spinal cord.
33 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
The Hippo pathway member Nf2 is required for inner cell mass specification
Katie Cockburn1,2, Steffen Biechele1,2, Jodi Garner1 and Janet Rossant1,2
1
Program in Developmental and Stem Cell Biology, The Hospital for Sick
Children Research Institute, Toronto, ON, Canada
2
Department of Molecular Genetics, University of Toronto, Toronto, ON,
Canada
During mammalian development, the first two lineages to be specified are
trophectoderm (TE) and inner cell mass (ICM). The Hippo pathway kinases Lats
1 and 2 (Lats1/2) and the transcriptional co-activator Yap play important roles
in this specification process. In outside cells of the embryo, Yap is nuclearlocalized and cooperates with Tead4 to induce the TE-specifying transcription
factor Cdx2. In inside cells, Lats1/2 phosphorylate Yap and prevent its nuclear
localization. The factors acting upstream of Lats1/2 and Yap in this context
have not been identified. Here, we demonstrate that the upstream Hippo
pathway member Nf2/Merlin is required for Lats1/2-dependent Yap
phosphorylation in the preimplantation embryo. Injection of dominant negative
Nf2 mRNA causes Yap mislocalization and ectopic Cdx2 expression, effects that
can be rescued by overexpression of Lats2 kinase. Zygotic Nf2 mutant
blastocysts have mild defects in Yap localization and Cdx2 expression, but
these become much more severe upon removal of both maternal and zygotic
Nf2. The inside cells of maternal/zygotic mutants fail to establish a pluripotent
ICM and form excess TE, resulting in peri-implantation lethality. Together,
these data establish a clear role for Nf2 upstream of Yap in the preimplantation
embryo and demonstrate that Hippo signaling is essential to segregate the ICM
from the TE.
34 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
The C. elegans Argonaute CSR-1 Licenses Germline Gene Expression
Christopher J. Wedeles, Monica Z. Wu, Julie M. Claycomb
Department of Molecular Genetics, University of Toronto, Canada
Several small RNA-mediated gene silencing pathways that defend their
endogenous genomes against foreign nucleic acids have been well
characterized. While less understood, small RNA pathways are also strong
candidates for maintaining a balance between the silencing of exogenous
(nonself) sequences and the appropriate expression of endogenous (self)
sequences.
In C. elegans, the germline piRNA pathway encodes more than 30,000 unique
21-nucleotide piRNAs, which silence a variety of foreign nucleic acids. Left
unchecked, this system would have the potential to silence nearly the entire
germline transcriptome. What mechanisms allow endogenous germlineexpressed transcripts to evade silencing by the piRNA pathway? One likely
candidate is the germline-expressed Argonaute, CSR-1, which interacts with a
subset of 22G-small RNAs that are complementary to nearly all germline
transcripts.
We developed an in vivo RNA tethering assay and demonstrated that the
recruitment of CSR-1 to a transcript licenses its transcription, protecting it
from piRNA-mediated silencing. Furthermore, tethering CSR-1 to a previously
silenced locus transcriptionally activated its expression. Remarkably, we also
observed that over the course of several generations, CSR-1 was capable of
activating the expression of a transcript possessing no tethering sites.
Together, these results demonstrate a rare positive role for an Argonaute
pathway in heritably licensing germline transcription.
35 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Molecular mechanisms for building a secretory cell
Konstantin Khetchoumian, Aurélio Balsalobre, Helen Christian, Valérie Chénard,
Julie St-Pierre and Jacques Drouin
The pituitary is an endocrine gland containing six cell lineages specialized in
large-scale hormone production. For example, proopiomelanocortin (POMC)secreting cells increase their hormone production about 100-fold postnatally.
Tpit is a POMC cell-specific transcription factor (TF) driving terminal
differentiation of POMC lineages. While normal POMC cells increase their size
and organelle content after birth, Tpit-deficient cells remain small and have
few secretory organelles. We used the Tpit knockout model to query
mechanisms required for establishment of the secretory apparatus. We found
that Tpit controls the gene regulatory network for implementation of secretory
capacity through direct transcriptional stimulation of Creb3l2 and XBP1, two
critical TFs regulating the Unfolded Protein Response (UPR). Moreover, Tpit
directly targets promoters/enhancers of downstream secretory pathway genes
through tethering with Creb3l2 and XBP1. Gain-of-functions for Creb3l2 and
XBP1 led to increased cell size, organelle, protein and RNA contents, hormone
secretion and a metabolic shift from anaerobic glycolysis toward the more
energy efficient oxidative phosphorylation.
Classically UPR is known as a cytoprotective stress response to protein
misfolding and it is associated with decreased protein synthesis. The UPR has
also been suggested to promote secretory capacity (“physiological UPR”).
Remarkably, we found that the highly tissue-specific TF Tpit uses UPR pathways
to increase hormone production and transform POMC cells into “hormone
producing factories”.
36 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
The linear ubiquitin-specific deubiquitinase Gumby/Fam105b regulates
angiogenesis.
Stephanie M. Almeida, Elena Rivkin, Derek F. Ceccarelli, Yu-Chi Juang, Teresa
A. MacLean, Tharan Srikumar, Hao Huang, Wade H. Dunham, Ryutaro
Fukumura, Gang Xie, Yoichi Gondo, Brian Raught, Anne-Claude Gingras, Frank
Sicheri & Sabine P. Cordes
The formation of the vasculature network is critically important during
embryonic development and requires the coordination of multiple signalling
pathways. We have characterized two distinct mutations in the (uro)chordatespecific Gumby/Fam105b gene that disrupt embryonic angiogenesis to different
degrees. Gumby encodes an Ovarian Tumor Domain (OTU) class of
deubiquitinase (DUB) that specifically cleaves linear ubiquitin linkages. A
crystal structure of Gumby in complex with linear di-ubiquitin reveals how the
identified mutations adversely impact substrate binding and catalytic function
in line with the severity of their angiogenic phenotypes. A mass spectrometry
screen revealed Gumby interacts with HOIP/RNF31, the catalytic component of
the linear ubiquitin assembly complex (LUBAC). In gumby mutant mouse
embryos, levels of linear ubiquitination are increased. Furthermore, Gumby
can counteract activation of LUBAC dependent NF-kappaB-dependent
transcription. Gumby protein also interacts with disheveled 2 (Dvl2), a central
component of Wnt signaling pathways. We found that Gumby is expressed in
canonical Wnt-responsive cells and can modulate the canonical Wnt pathway in
vitro and in vivo. Our analyses also illustrate that while Gumby activates
canonical Wnt signaling, LUBAC inhibits this. Thus, for the first time, we have
shown that linear (de)ubiquitination plays key roles in modulating Wnt
signalling and angiogenesis.
37 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
ONGLET 2
POSTER SESSION A
38 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
SESSION A / POSTER SESSION A
Tuesday, March 18th, 16h30 - 18h30
A-1 Rana Amini - Université de Montréal
The short Anillin ANI-2 promotes intercellular bridge stability to
maintain syncytial organization of the C. elegans germline
A-2
Siavash Amon - McMaster University
Regulation and Function of the LIM-Hox Gene lin-11 in C. elegans
Development
A-3
Michel Arsenault - University of Prince Edward Island
Reduced nephron endowment in the absence of Sox4
A-4
Megha Bajaj - University of Alberta
Laulimalide induces dose dependent modulation of microtubule
behaviour in the C. elegans embryo
A-5
Karl-F. Bergeron - Université du Québec à Montréal (UQAM)
A novel lncRNA with critical roles in neural crest cell development
A-6
Forum Bhanshali - Institut de recherche en immunologie et en
cancérologie (IRIC)
Functional analysis of the PAR-5/14-3-3-dependent signaling network
during cell polarization
A-7
David Brown - The Hospital for Sick Children
Identification of planarian transcription factors required for brain
regeneration
A-8
Maxwell Burg - University of Manitoba
Role of β-integrin in mediating pharyngeal gland cell migration during
Caenorhabditis elegans development
A-9
Kevin Chan - University of Toronto
An EVA-1 UNC-40 Complex Mediates Attraction to the MADD-4 Guidance
Cue in Caenorhabditis elegans
A-10 Karunatilleke Chanaka - Dalhousie University
Ascophyllum nodosum (L.) Le Jolis. Extract Mitigate Water Stress in
Tomato (Solanum lycopersicum L.)
A-11 Emma Chaston-Vickers - University of New Brunswick
Visualization and quantification of matrix metalloproteinase activation
in vivo using double epitope tagged reporters
39 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
A-12 Preston Chin - McGill University
EKL-7 is a putative MPK-1 Erk target during excretory duct cell fate
Specification
A-13 Rami Darwich - University of Ottawa
Investigating KLF13 transcriptional partnership with TBX5 in the heart
A-14 Jean-François Denis - Université de Montréal
Differential regulation of Smad2 and Smad3 in limb regeneration
A-15 Daniel Dennis - University of Calgary
Elucidating the regulatory mechanisms that modulate Neurog2 proneural
activity
A-16 Joey Doel - University of Western Ontario
Wnt and Hedgehog Signalling Regulate Extraembryonic Endoderm
formation
A-17 W. Brent Derry - The Hospital for Sick Children,
Modeling cerebral cavernous malformations in C. elegans
A-18 Catherine Descoteaux - Institut de recherche en immunologie et en
cancérologie (IRIC)
Characterization of regulators of PAR-4/LKB1 signalling using
C. elegans
A-19 David Desjardins - McGill University
A regulated response to oxidative stress: How mitochondrial oxidative
stress regulates behaviour and signaling in C. elegans
A-20 Tiphaine Dolique - Institut de recherches cliniques de Montréal (IRCM)
Loss of depth perception by genetic silencing of ipsilateral retinal
projections
A-21 Serena D'Souza - University of Toronto
MADD-3, a LAMMER Kinase, is a Potential Regulator of Receptor
Trafficking in the C. elegans muscle
A-22 Brian F. Eames - University of Saskatchewan
Chemical biology in the embryo: Imaging sulfur in cartilage matrix of
proteoglycan mutants
A-23 Michael Fairchild - University of British Columbia
The actin binding protein profilin controls soma-germline interactions in
the Drosophila testes
40 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
A-24 Amina Fallata - University of New Brunswick
Intracellular localization and regulation of Gelatinase A in zebrafish
skeletal muscle
A-25 Qingping Feng - University of Western Ontario
Rac1 is critical to cardiomyocyte polarity and embryonic heart
development
A-26 Shengrui Feng - University of Ottawa
Lineage Tracing of Neuronal Progenitor Cells Expressing dlx Genes in the
Zebrafish Brain
A-27 Lauren Fogarty - University of Newfoundland
Roles Mcl-1 and Bcl-xL in nervous system development
A-28 Claudia Gentile - Institut de recherches cliniques de Montréal (IRCM)
New Tools for the Study of Limb Development
A-29 Abigail Gerhold - Institut de recherche en immunologie et en cancérologie
Investigating stem cell mitosis in vivo by live-imaging in C. elegans
A-30 Lara Gharibeh - University of Ottawa
Essential role for the GATA6 transcription factor in heart development
A-31 Hannah Goldberg - University of Western Ontario
ATRX deficiency in the development and progression of glioma
A-32 Eugénie Goupil - Institut de recherche en immunologie et en cancérologie
Regulation of cortical loading of the scaffold protein ANI-2 during
syncytial formation of the C. elegans germline
A-33 Jennifer Grants - University of British Columbia
The kinase module of the Mediator complex regulates EGFR signaling to
influence cell fate decisions in C. elegans
A-34 Peng Huang - University of Calgary
Maintenance of muscle integrity by Hedgehog signaling
A-35 Kingsley Ibhazehiebo - University of Calgary
Neurodevelopmental exposure to bisphenol a induces locomotor
hyperactivity and perturbs hypothalamic neurogenesis in zebrafish
A-36 Michelle Im - University of Western Ontario
Role of integrin-linked kinase on epidermal keratinocyte survival
41 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
A-37 Bradley Jackson - University of Western Ontario
A novel RhoG-ILK/ELMO2-Rac1 pathway stabilizes microtubules.
A-38 Pratik Kadekar - McGill University
LKB1/PAR-4 regulation of signaling C. elegans dauer germline quiescence
A-39 Anna Kazanets - McGill University
Global genomic survey to investigate the role of AMPK in germline stem
cell quiescence in C. elegans dauer.
A-40 Yacine Kherdjemil - Institut de recherches cliniques de Montréal (IRCM)
Transcriptional regulation and function of Hoxa11: a role for antisense
transcription
A-41 Shinhye Kim - University of Manitoba
Molecular mechanism of egl-15/FGFR and ina-1/α-integrin regulation of
pharyngeal gland cell migration in Caenorhabditis elegans
A-42 Marine Lacomme - Institut de recherches cliniques de Montréal (IRCM)
LGN regulates asymmetric cell divisions by controlling mitotic spindle
orientation in the developing mouse retina
A-43 Robert Lalonde - University of Ottawa
Regulation of actinodin1 via tissue specific cis-acting regulatory elements
A-44 Melissa Lavictoire - University of Ottawa
Biochemical characterization of zebrafish Parla and Parlb
A-45 Chris Law - Institut de recherches cliniques de Montréal (IRCM)
Emergence of Motor Circuit Activity
A-46 Vicki Leggo – University of Prince Edward Island
Defining Sox11 and Combined Sox4/Sox11 Function in the Kidney
A-47 Lea Lepelletier - Institut de recherches cliniques de Montréal (IRCM)
The Sonic hedgehog (Shh) signaling pathway requires ZBP1-mediated
local translation to guide commissural axons
A-48 Vicki Leung - McGill University
The planar cell polarity protein Vangl2 is essential for retinal and optic
nerve development
A-49 Alexander Lin - The Hospital for Sick Children
Planarian Yorkie functions as a crucial node in stem cell maintenance and
organ patterning
42 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
The short Anillin ANI-2 promotes intercellular bridge stability to maintain
syncytial organization of the C. elegans germline
Rana Amini1, Eugénie Goupil1, Sarah Labella2, Monique Zetka2, Amy S. Maddox3,
Nicolas T. Chartier1 and Jean-Claude Labbé1
1
Institut de recherche en immunologie et en cancérologie (IRIC), Université de
Montréal, QC, Canada. 2Department of Biology, McGill University, Montréal,
QC, Canada. 3Department of Biology, University of North Carolina, Chapel Hill,
NC, USA.
Cytokinesis is the physical separation of the two daughter cells, after mitosis.
However, biogenesis of some tissues, such as germline of most animals,
requires that daughter nuclei remain connected to a shared cytoplasm, or
syncytium, through incomplete cytokinesis. We studied syncytial formation
using the C. elegans germline, a tubular syncytium in which germ cells (GC)
connect to a shared cytoplasm core (the rachis) via intercellular bridges. We
found that the syncytial architecture of the germline initiates early in larval
development and GCs become progressively interconnected until adulthood.
The Anillin scaffold protein ANI-2 is enriched at GC intercellular bridges from
the onset of GC specification, and only few GCs of ani-2 mutants have
intercellular bridges, indicating that ANI-2 controls germline syncytial
organization. Interestingly however, germline development and GC nucleus
partitioning were normal in ani-2 mutants until hermaphrodite animals
completed larval development, when GCs became multinucleated via collapse
of intercellular partitions. Multinucleation was rescued by blocking the
cytoplasmic streaming that typically initiates in the rachis of young adult
animals to promote oocyte growth, prior to ovulation. We propose that ANI-2
promotes GC syncytial organization and allows compensation for the
mechanical stress associated with oogenesis by conferring stability to GC
intercellular bridges.
43 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Regulation and Function of the LIM-Hox Gene lin-11 in C. elegans
Development
Siavash Amon and Bhagwati Gupta
McMaster University, Hamilton L8S-4K1, Ontario, Canada.
LIM-Hox genes are a sub-family of Hox genes that play important roles in
animal development. The nematode C. elegans contains seven LIM-Hox family
members including a founding family member lin-11. lin-11 is important for the
development of the reproductive system and neuronal differentiation.
Mutations in lin-11 cause an egg laying-defective phenotype that is caused by
abnormalities in the formation of the vulva and vulva-uterine connection. The
neuronal defects in lin-11 animals affect behaviors such as chemotaxis,
electrotaxis and thermotaxis.
To understand how LIN-11 controls diverse processes, we are performing a
structure-function analysis of the gene. This has involved dissecting the
enhancer regions of lin-11 to identify upstream regulators and signaling
pathways. Similarly, we are carrying functional analyses of lin-11 conserved
domains by creating truncated LIN-11 proteins.
Finally, we are also testing the functional conservation between lin-11 and its
orthologs in other organisms, specifically the fruit fly Drosophila melanogaster
and mouse Mus musculus. For this, we are attempting to rescue the
reproductive system and neuronal defects in the lin-11 null mutant by
introducing dLim1 and mLhx1 genes. The results of these experiments will
ultimately improve our understanding of the cellular and molecular roles of
LIM-Hox genes during development and diseases.
44 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Reduced nephron endowment in the absence of Sox4
Michel G. Arsenault, Ashley Patriquen, Blanca P. Esparza Gonzalez, Glenda M.
Wright and Sunny Hartwig
Department of Biomedical Sciences, Atlantic Veterinary College, University of
Prince Edward Island, 550 University Avenue, Charlottetown, PE, C1A 4P3,
Canada
Defects in nephrogenesis and ureteric branching result in Congenital Anomalies
of the Kidney and Urinary Tract (CAKUT). Nephron deficiency is a hallmark
feature of CAKUT. Low nephron endowment - although asymptomatic early in
life - is associated with adult-onset hypertension, a leading cause of coronary
heart disease, stroke, and renal failure in North America. We have previously
identified the Sox4 transcription factor as essential for normal renal
development in vivo. Conditional ablation of Sox4 in nephron progenitor cells
and their derivatives results in early-onset glomerular injury, which progresses
to end-stage renal failure in mice. Here we report that low nephron
endowment is a primary developmental defect in Sox4-deficient mice; Cultured
Sox4-deficient kidney explants exhibit a 47% reduction in pretubular aggregate
formation at embryonic day (E) 12.5 (n=24 wildtype, n=21 knockout), and a 36%
reduction in glomerular number is observed at E17.5. Current experiments are
underway to investigate whether reduced nephron endowment in Sox4deficient kidneys may be due to increased apoptosis, decreased proliferation,
or a change in cell fate of nephron progenitor cells during nephrogenesis in
vivo.
45 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Laulimalide induces dose dependent modulation of microtubule behaviour
in the C. elegans embryo
Megha Bajaj and Martin Srayko
Department of Biological Sciences, University of Alberta, Edmonton, Alberta
T6G 2E9
Laulimalide is a microtubule-binding drug originally isolated from a marine
sponge. In vitro and in vivo studies have shown that high concentrations of
laulimalide stabilize microtubules and inhibit cell division similarly to
paclitaxel; however, there are important differences with respect to the
nature of the specific cellular defects between these two drugs and their
binding sites. In the present study we used the C. elegans one-cell embryo to
investigate the acute effects of laulimalide in vivo. The first mitotic division in
C. elegans takes about 20 minutes for completion and the microtubule-based
processes in the one-cell embryo are highly stereotypical and studied in detail.
This makes the C. elegans embryo an excellent model for testing acute effects
of drugs. Our experiments indicate that laulimalide induces a concentrationdependent, biphasic change in microtubule polymer dynamics in the embryo.
Microtubules were stabilized at concentrations above 100 nM, but destabilized
at concentrations between 50 and 100 nM. In addition, we found that
laulimalide acted synergistically with paclitaxel by stabilizing microtubules
when both drugs were applied together at sub-effective concentrations. This is
the first report, which shows that C. elegans microtubule network responds
differentially to varying concentrations of laulimalide, compared with
paclitaxel.
46 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
A novel lncRNA with critical roles in neural crest cell development
Karl-F. Bergerona, David W. Silversidesb, Nicolas Pilona
a
BioMed research centre, UQÀM; bAnimal reproduction research centre,
University of Montreal
Neural crest cells (NCC) are a multipotent, transitory cell population that
migrates extensively, proliferates and differentiates in order to contribute to
several embryonic structures. NCC form, among other things, melanocytes as
well as peripheral neurons and their associated glia. A random insertional
mutagenesis screen has revealed many genes/loci important for NCC
development in mice. One mouse line, Spot, displays abnormal pigmentation
combined with intestinal motility and spatial orientation defects, resulting
respectively from enteric and inner ear developmental problems. This
phenotype is reminiscent of Waardenburg syndrome (WS), a complex human
genetic condition that affects pigmentation and the inner ear, and sometimes
includes aganglionic megacolon – an absence of neuronal ganglions in the distal
bowel leading to intestinal blockage. In Spot animals, fluorescent marking of
NCC has shown a defect in hindgut colonization. Histological analysis of the
inner ear has shown a collapse of the membranous labyrinth and a lack of
vestibular melanocytes. Given the necessary role of melanocytes in endolymph
homeostasis in the cochlea, we suggest that melanocytes are also important for
endolymph maintenance in the vestibule. The Spot mutation disrupts a single
isoform of the newly identified lncRNA A830082K12Rik and genetically interacts
with Pax3, another gene involved in WS. In conclusion, we identified a novel
transcript as a critical regulator of NCC development. Its human homolog
NR2F1-AS should thus be considered as a new player in the etiology of WS.
47 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Functional analysis of the PAR-5/14-3-3-dependent signaling network during
cell polarization
Forum Bhanshali, Jacob A. Galan, Laura Benkemoun, Philippe P. Roux, JeanClaude Labbé
Institut de recherche en immunologie et en cancérologie (IRIC), Université de
Montréal, QC, Canada.
Anterior posterior polarity in early zygote of C. elegans is required for
asymmetric cell division, an event that is prerequisite for proper patterning
during embryonic development. Previous work from several groups suggest that
PAR-5, a 14-3-3 protein, acts as a central regulator of polarity establishment by
binding to serine/threonine phosphorylated motifs found in polarity regulators.
However, the mechanistic detail by which PAR-5 regulates polarity formation is
unknown. We hypothesize that there are unidentified regulators of cell polarity
that mediate their effect by interacting with PAR-5. To address this, we have
performed glutathione S-transferase pull-down assays with a PAR-5 fusion
protein followed by LC-MS/MS analysis to uncover unique interactors of PAR-5
in C. elegans lysates. To identify the polarity-relevant PAR-5 interactors, we
have performed RNAi-based analysis in a C. elegans par-1 temperature sensitive
mutant allele. Through our suppression assays, we found that depletion of the
ribosomal protein RPL-17, as opposed to most other ribosomal proteins, can
specifically suppress the lethality associated with the conditional mutant par1(zu310). We are currently testing whether RPL-17 acts through its ribosomal
activity. Our preliminary results indicate that RPL-17 is a binding partner of
PAR-5 and the genetic interaction revealed by RNAi suggests that this
interaction is functionally relevant for embryonic polarity.
48 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Identification of planarian transcription factors required for brain
regeneration
Brown, DDR and Pearson, BJ
The Hospital for Sick Children, Toronto, Ontario, Canada.
Schmidtea mediterranea, a freshwater planarian, has emerged as a unique
model system due to its ability to regenerate all of its tissues from a population
of totipotent adult stem cells. S. mediterranea is a powerful model with which
to study neural regeneration because it possesses a morphologically simplistic,
but molecularly compartmentalized CNS comprised of a cephalic ganglia (brain)
and two ventral nerve cords. Recent studies have demonstrated conserved
roles for various transcription factors in planarian regeneration, indicating a
high level of evolutionary conservation among these factors. To identify
transcription factors that are important for brain regeneration, we employed
RNA Deep Sequencing to compare the transcriptomes of worms that are
regenerating normally, regenerating ectopic brains (through β–catenin RNAi)
and regenerating no brains (through apc RNAi). Transcription factors exhibiting
differential expression between worms regenerating ectopic brains and worms
regenerating no brains are currently being examined to test their function
during brain regeneration. Identification of transcription factors that
participate in brain regeneration may highlight core mechanisms to induce
neural regeneration in other organisms.
49 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Role of β-integrin in mediating pharyngeal gland cell migration during
Caenorhabditis elegans development.
M. Burg, S.R. Kim and J. Kormish
Biological Sciences, University of Manitoba, Winnipeg, MB, Canada
During pharynx development in Caenorhabditis elegans, the dorsal gland cell,
g1p, is born in the anterior aspect of the pharyngeal primordium and migrates
to the posterior pharynx using a process called retrograde extension. In ina-1
(α-integrin subunit) mutants, the g1p pharyngeal gland cell over-migrates to an
aberrant posterior position located near the intestine. Integrins typically
function as α and β heterodimers but several null mutations in pat-3, the best
studied β-integrin in C. elegans, have displayed no defects in gland cell
migration. For my research, I will test three possible models for the role of βintegrin in gland cell migration. 1) RNAi against pat-3 will be used to determine
if pat-3 is being maternally supplied to rescue migration defects. 2) Similar
pat-3 RNAi experiments in the ina-1 mutant background will test if ina-1 is
negatively regulating pat-3 function. 3) I will characterize a truncated version
of β-integrin, C05D9.3, to determine if it may be the β-integrin subunit that
interacts with ina-1 to control gland cell migration.
50 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
An EVA-1 UNC-40 Complex Mediates Attraction to the MADD-4 Guidance Cue
in Caenorhabditis elegans
Kevin Chan1,2, Ashwin Seetharaman 1,2,3, Rachel Bagg1,2, Guillermo Selman1,2,
Yuqian Zhang1,2, Joowan Kim1, and Peter J. Roy1,2,3,4
1
Department of Molecular Genetics, University of Toronto, Toronto, ON, M5S
1A8
2
The Donnelly Centre for Cellular and Biomolecular Research, University of
Toronto, Toronto, ON, M5S 3E1
3
The Collaborative Programme in Developmental Biology, University of Toronto,
Toronto, ON, M5S 3E1
We recently discovered a secreted and diffusible midline cue called MADD-4 (an
ADAMTSL) that guides migrations along the dorsoventral axis of the nematode
C. elegans. We showed that the transmembrane receptor, UNC-40 (DCC),
whose canonical ligand is the UNC-6 (netrin) guidance cue, is required for
extension towards MADD-4. Here, we demonstrate that MADD-4 interacts with
an UNC-40/EVA-1 co-receptor complex to attract cell extensions. EVA-1 is a
conserved transmembrane protein with predicted galactose-binding lectin
domains. EVA-1 enables UNC-40 to respond to MADD-4 in the presence of UNC6; in EVA-1’s absence, UNC-40 responsiveness to MADD-4 is limited and is
instead dominated by UNC-6; in UNC-6’s absence, UNC-40’s responsiveness to
MADD-4 becomes less dependent on EVA-1. By enabling UNC-40 to respond to
MADD-4 in the presence of UNC-6, EVA-1 may increase the precision by which
UNC-40-directed processes can reach their MADD-4-expressing targets within a
field of MADD-4 and UNC-6 guidance cues.
51 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Ascophyllum nodosum (L.) Le Jolis. Extract Mitigate Water Stress in Tomato
(Solanum lycopersicum L.)
Nadun Chanaka Karunatilleke1, Yousef Papadopolous2, Balakrishnan Prithiviraj1
1
Department of Environmental Sciences, Dalhousie University, PO Box 550,
Truro, NS, B2N 5E3
2
Department of Plant and Animal Science, Dalhousie University, PO Box 550,
Truro, NS, B2N 5E3
Growth and development of a plant is affected by a number of biotic and
abiotic stresses such as; water, salinity, frost and pathogens. Seaweeds and
their extracts have been used in agriculture to mitigate biotic and abiotic
stresses. However, the effect of seaweed extract on plant under water stress
has not been investigated. In the current study we investigated the effect of
the brown alga Ascophyllum nodosum (L.) Le Jolis. extract (ANE) to mitigate
water stress in tomato. The application of ANE affected wilting, stomatal
conductance, water potential and plant recovery after water stress. Further,
the extract also affected antioxidant enzymes and transcription abundance of
stress response genes in tomato leaves. A larger percentage (85%) of plant that
received the extract treatment recovered from a severe water stress as
compared to control plants (30-40% recovery). It was also evident the extract
treated plants had higher stomatal conductance, high plant water potential
and subsequently less wilting. Moreover, the antioxidant enzymes and
transcript abundance of stress response genes were less in ANE treated plants.
Taken together the results suggest that ANE had significant positive effect on
protecting tomato plant against water stress.
52 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Visualization and quantification of matrix metalloproteinase activation in
vivo using double epitope tagged reporters
Emma J. Chaston-Vickers and Bryan D. Crawford
Department of Biology, University of New Brunswick, Fredericton, New
Brunswick
Matrix metalloproteinases (MMPs) are best known for their role in tissue
remodelling, making them of great interest to both developmental biologists
and pathologists. However, investigations into the regulation of MMP activity
are hindered by the lack of assays yielding biologically relevant information.
MMPs are primarily activated by post-translational proteolytic trimming of
auto-inhibitory N-terminal domains. Assays for gene expression and protein
localization provide no information about protease activation. We have
developed a novel epitope-mediated MMP activation (EMMA) assay, in which
catalytically-inactive proteases with N- and C-terminal epitope tags are
expressed in vivo. The activity of endogenous regulatory mechanisms is
visualized by ratioing signals from the tags using confocal microscopy or
quantified by western blot analysis of tagged bands from tissue homogenates.
We are establishing a line of transgenic zebrafish expressing EMMAed Mmp2
under regulation of the heat shock promoter. This will allow Mmp2 localization
and activation to be visualized and quantified in vivo, along with the effects of
experimental perturbations on the activation of this ubiquitous effector of
tissue remodelling.
53 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
EKL-7 is a putative MPK-1 Erk target during excretory duct cell fate
specification
Preston Chin, Phil Cheng, and Christian E. Rocheleau
Department of Medicine and Anatomy and Cell Biology, McGill University
The Caenorhabditis elegans Ras/Mitogen Activated Protein Kinase (MAPK)
signaling pathway regulates the determination and maintenance of the
excretory duct cell (EDC) fate, loss of which results in phenotypically distinct
larval “rod-like” lethality. Scaffolding proteins Kinase Suppressor of Ras (KSR),
KSR-1 and -2, are redundantly required for Ras/MAPK signaling. ksr-1 null
mutants exhibit a wild-type phenotype but are sensitive to any reductions in
Ras/MAPK signaling. We identified Y39G10AR.7 (ekl-7) in both an RNAi and a
mutagenesis screen as an enhancer of ksr-1 lethality. EKL-7 is a novel protein
with a cluster of Erk phosphorylation and docking sites similar to those found in
MPK-1 Erk targets LIN-1 and EOR-1. ekl-7(vh20) single mutants are essentially
wild-type, but enhance the rod-like lethality of lin-1 and eor-1 mutants
suggesting it might function in parallel. ekl-7(vh20); ksr-1 animals appear to
have an EDC, but often display large vacuoles adjacent to it. Therefore, ekl-7
might regulate EDC migration, stacking with the G1 pore cell, or junction
maintenance.
54 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Investigating KLF13 transcriptional partnership with TBX5 in the heart
Darwich, R. and Nemer, M.
Faculty of Medicine, University of Ottawa, Ottawa, Canada
Congenital heart defects (CHD) comprise the largest class of birth defects in
humans and are a major cause of infant mortality and morbidity.
Unfortunately, identifying the aberrant molecular and genetic pathways
underlying CHD is still a challenging puzzle. We have previously demonstrated
that the zinc-finger kruppel-like transcription factor KLF13, expressed
predominantly in the atria, binds evolutionarily conserved regulatory elements
known as CACC-box on cardiac promoters. Although our knock-down of KLF13
in Xenopus embryos was associated with atrial septal defects (ASD), this
phenotype was not reproduced in our mouse model. In the current study,
using in vivo and in vitro approaches, we examined KLF13’s mechanism of
action in mice by investigating its transcriptional activity and its partnering
profile with the T-box transcription factor TBX5 which is directly linked to
familial ASD. Also, we report that some TBX5 mutant proteins associated with
human congenital heart defects were found to have impaired functional and
physical interaction with KLF13. These experiments provide novel insight into
the role of KLF13 in cardiac transcription and suggest that KLF13 may be a
genetic modifier of human congenital heart diseases.
55 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Differential regulation of Smad2 and Smad3 in limb regeneration
Jean-François Denis1 and Stéphane Roy
1
2
1,2
Dept. of Biochemistry
Dept. of Stomatology, Université de Montréal, Montreal, Quebec, H3T 1J4,
Among vertebrates, axolotls (Ambystoma mexicanum) have the unique ability
to perfectly regenerate many parts of their body following injury or
amputation. Blocking TGF-β signalling with a pharmacological antagonist (SB431542) inhibits the regeneration process, but specific functions of intracellular
effectors Smad2 and Smad3 remain unknown.
Treatment of amputated limbs with SB-431542 does not prevent closure of the
wound but the blastema does not form. We thus hypothesised that cellular
migration and proliferation of blastema cells is linked to the activation of Smad
effectors. Results indicate that Smad2 and Smad3 are differentially regulated
during the regenerative process. Maximal phosphorylation of Smad2 occurs
within the first 48h which coincides with cellular migration, before blastema
formation whereas phosphorylation of Smad3 occurs much earlier (3h postamputation). In addition, phosphorylation of Smad2 is blocked in SB-431542
treated limbs and total Smad3 is downregulated. RT-PCR analysis also show
that the increase of TGF- β target genes MMP2, MMP9 and TIMP1 expression are
not upregulated in SB-431542 treated regenerating limbs.
In conclusion, fine tuning of signalling pathways is essential for proper
regeneration to take place. Future work will focus on functional analysis of
Smad proteins as they are critical in mediating TGF-β signalling which is
essential for the regeneration process.
56 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Elucidating the regulatory mechanisms that modulate Neurog2 proneural
activity
Daniel Dennis, Chris Kovach, Dawn Zinyk, Carol Schuurmans
The neocortex contains six neuronal layers that are generated sequentially
during development, arising from a common progenitor pool. Cortical
progenitors not only know when to differentiate, and which neuronal
phenotype to acquire, but also which mode of division to undergo (i.e.,
symmetric or asymmetric, proliferative or differentiative) to avoid premature
progenitor depletion and generate correct neuronal numbers. We study the role
of the proneural transcription factor Neurog2 in controlling progenitor cell
dynamics. Neurog2 normally oscillates in 2-3 hr cycles in dividing progenitors,
whereas its expression is sustained in differentiating progenitors. To test
whether sustained Neurog2 expression influences progenitor behaviour, we
generated a conditional gain-of-function transgenic line in which Neurog2 is
constitutively overexpressed upon Foxg1-creKI-mediated deletion of a floxed
“stop” cassette. We found that sustained Neurog2 expression drastically
reduces neocortical size and neuronal number, with a proportionate increase in
early-born neurons in the lateral cortex (where Neurog1 is expressed), whereas
neuronal proportions are normal (although numbers are down) in the medial
cortex (where Neurog1 is not expressed). Notably, in transcriptional assays,
Neurog1 inhibits Neurog2 function. We propose a novel model, whereby
Neurog2 function is modulated not only by its cyclic behavior, but also by
inhibitory actions of the related factor, Neurog1.
57 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Wnt and Hedgehog Signalling Regulate Extraembryonic Endoderm Formation
Gurjoth Deol, Jason T. K. Hwang, Gregory Golenia and Gregory M. Kelly
Department of Biology, Molecular Genetics Unit, and Child Health Research
Institute, Western University, London, ON, N6A 5B7
The first epithelial-to-mesenchymal transition in mouse development occurs
when ICM cells differentiate into extraembryonic endoderm (XEN); an event
mimicked when F9 cells are exposed to retinoic acid (RA). Inhibiting Wnt
signalling with XAV-939 blocks differentiation, while activated canonical bcatenin signalling induces XEN. While an increase in Hedgehog expression
accompanies RA-induced differentiation, Cyclopamine, a Hh pathway inhibitor,
blocks XEN formation. Together, these results indicate that Wnt and Hh
signalling are necessary for XEN differentiation, but whether the pathways
work in conjunction or independently, remains unknown. To address this, cells
were treated with BIO to activate canonical Wnt signalling and then
Cyclopamine. Results, using a b-catenin reporter assay that showed no Tcfdependent transcription, would suggest that active Hh signalling is required to
mediate Wnt signalling. For reciprocal experiments, cells stably expressing
constitutively active GSK-3 will be treated with SAG, the latter to activate Hh
signalling. Reporter assays will determine if blocking canonical b-catenin
signalling affects Tcf-dependent and Gli-dependent transcription. Immunoblots
and qPCR will be used to assess for XEN differentiation. Together, these results
will determine the relationship between Hh and Wnt signalling in XEN
differentiation.
58 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Modeling cerebral cavernous malformations in C. elegans
W. Brent Derry*
Program in Developmental and Stem Cell Biology, The Hospital for Sick
Children, Toronto, M5G 0A4, Canada
The C. elegans excretory cell is a single-cell seamless tube that develops
through the concerted action of cytoskeletal dynamics and endosomal
trafficking. We show that ccm-3, a gene that causes the neurovascular disease
cerebral cavernous malformations (CCM) in humans, promotes excretory canal
growth and maintenance through its binding partners GCK-1 and striatin (CASH1); the STRIPAK complex. Ablation of ccm-3, gck-1 or cash-1 cause canal
truncations and formation of cysts along their basal surfaces. We show that
these genes promote endosome recycling, which ultimately affects the
dynamics of the canal’s vesicular membrane reservoir (canaliculi). With
functional CCM-3/STRIPAK components, these canaliculi aggregate to form the
lumen and promote extension of the growth canal. In an RNAi screen for ccm-3
pathway components, we identified the myotonic dystrophy-related Cdc42
binding kinase mrck-1 and the exocyst gene exoc-8, which are implicated in
vesicle formation (via Cdc42 signaling) and recycling endosome delivery,
respectively. Both mrck-1 and exoc-8 are required for tube growth and
membrane integrity, similar to ccm-3/STRIPAK. We propose that the C. elegans
excretory canal provides a genetically tractable model for understanding
cerebral cavernous malformations.
59 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Characterization of regulators of PAR-4/LKB1 signalling using C. elegans
Catherine Descoteaux, L. Benkemoun, N. Chartier, C. Monfort, P. Salazar, J.C.
Labbé
Institut de recherche en immunologie et en cancérologie (IRIC), Université de
Montréal, Canada.
Mutations in the gene lkb1, coding for a highly conserved serine/threonine
kinase, are responsible for the Peutz-Jeghers syndrome, which leads to the
formation of gastro-intestinal tumours in humans. The orthologue of lkb1 in the
nematode Caeonorhabditis elegans, termed par-4, regulates early polarization
and asymmetric cell division in the embryo. A mutation in the gene par-4
causes embryonic lethality by perturbing three main cellular processes:
asymmetric segregation of cell fate determinants, asynchronic regulation of
cell cycle progression and contractility of the actomyosin network. In order to
identify regulators of the PAR-4/LKB1-dependant pathways, we performed a
screen for suppressors of the embryonic lethality associated with a mutation in
par-4 and identified 6 genes. Most of these genes encode proteins not
previously implicated in cell polarization and have conserved homologs with
defined activities including protein phosphorylation, ubiquitilation, proteolysis
and scaffolding. We are currently using quantitative imaging of specific PAR-4dependant cellular events to determine which of these are controlled by each
suppressor during early C. elegans embryonic development. Molecular analysis
of these suppressors will reveal details on the mechanism through which PAR-4
regulates cell polarization and promotes asymmetric cell division.
60 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
A regulated response to oxidative stress: How mitochondrial oxidative stress
regulates behaviour and signaling in C. elegans
D.C. Desjardins, S. Hekimi
McGill University, Department of Biology
Aerobic respiration generates the ATP needed for cellular activities but it also
generates reactive oxygen species (ROS) in the process. ROS are potentially
damaging molecules but also function in signaling so respiring organisms
maintain a fine balance between ROS production and detoxification. The
toxicity of ROS has long been proposed to be a determinant of aging, as the
oxidative stress theory of aging proposes. More recent evaluation of ROS
biology indicates that the effect on aging is less straightforward than originally
thought and that ROS can affect the biology of organisms in much more diverse
ways.
The C. elegans clk-1 gene functions in the synthesis of ubiquinone, which is a
component of the electron transport chain. clk-1 mutants show numerous
developmental and behavioral phenotypes as well as deregulated ROS signaling.
For example, clk-1 affects Ras signaling during vulva development and affects
the defecation cycle by deregulating a novel steroid signaling pathway. We are
trying to understand how ROS act as a signal across cellular compartments by
studying how the activities of compartment-specific superoxide dismutases
(SODs) and catalases modulate ROS signaling in these pathways.
61 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Loss of depth perception by genetic silencing of ipsilateral retinal
projections
Tiphaine Dolique1,3 and Frédéric Charron1,2,3
1
Molecular Biology of Neural Development, Institut de recherches cliniques de
Montréal (IRCM), Montréal, QC, H2W 1R7
2
Department of Medicine, University of Montréal, Montréal, QC, H3T 1J4
3
Department of Anatomy and Cell Biology, Department of Biology, Division of
Experimental Medicine, Program in Neuroengineering, McGill University,
Montréal, QC, H3A 0G4
Binocular vision allows depth perception through the convergence of visual
information from both eyes to the brain. During development, most retinal
axons cross the midline at the optic chiasm toward the opposite side of the
brain (contralateral axons), while a small number of axons remain on the same
side (ipsilateral axons). Ipsilateral projections have been suggested - with no
formal proofs - to be important for depth perception.
Here we used a genetic approach to specifically silence the activity of
ipsilateral projections and investigate whether these projections are important
for depth perception. Synaptic transmission was suppressed in ipsilateral
projections (but not in contralateral projections) by expressing the tetanus
toxin light chain subunit (which inhibits neurosecretion) using a Cre-mediated
recombination approach. Using anterograde tracing techniques, we showed
that, expectedly: (1) the guidance of ipsilateral axons is unaffected in these
mutants, and (2) their refined distribution and segregation within their targets
are normal. However, and importantly, we found that these mice fail to detect
depth in a binocular visual test while maintaining proper general vision.
Therefore, our data, based on a genetic approach, provide for the first time a
clear demonstration of the specific requirement of ipsilateral retinal
projections for depth perception.
62 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
MADD-3, a LAMMER Kinase, is a Potential Regulator of Receptor Trafficking
in the C. elegans muscle
Serena D'Souza, Luckshika Rajendran, Louis Barbier and Peter Roy
Donnelly Center for Cellular and Biomolecular Research, Department of
Molecular Genetics, University of Toronto, Toronto, Ontario
Protein kinase families regulate a wide variety of cellular processes and are
often evolutionarily conserved in both structure and function. The LAMMER
kinase family is found ubiquitously throughout eukaryotes and members share a
highly conserved kinase domain. The most well described roles of LAMMER
kinase family members have been in the regulation of alternative splicing and
transcription factors, however the roles of cytoplasmic LAMMER kinases are not
well studied. madd-3, the C. elegans LAMMER homolog, was recovered by our
lab in screens for muscle arm development defective (Madd) mutants
conducted to identify components required for cell and cell extension
guidance. madd-3 has several characteristics that distinguish it phenotypically
from other Madd genes. MADD-3 is localized exclusively in the cytoplasm of the
muscle tissues, while most other Madd genes are expressed in both the nervous
system and muscle. As well, unlike other Madd genes madd-3 mutants are
synthetically lethal with unc-54, a myosin class II heavy chain. In order to
identify the function and substrate(s) of MADD-3 we exploited this synthetic
lethality to conduct a madd-3 suppressor screen. The screen recovered several
alleles of a pathway involved in receptor endocytosis. We are currently
investigating MADD-3’s role in endocytosis and its subsequent effects on cell
guidance.
63 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Chemical biology in the embryo: Imaging sulfur in cartilage matrix of
proteoglycan mutants
Mark J. Hackett1, Graham N. George1, Ingrid J. Pickering1, Brian F. Eames2
1
2
Department of Geology
Department of Anatomy and Cell Biology, University of Saskatchewan
Osteoarthritis is caused in part by the loss of proteoglycans (PGs, which are
sugar-coated proteins) in cartilage matrix. Sulfation, or the addition of sulfate
groups as esters, of PGs is thought to be important for at least two biological
roles of cartilage matrix that are relevant to defects in osteoarthritis patients:
tissue integrity and growth factor signaling. Despite the proposed role for PG
sulfation in the function of cartilage matrix, however, sulfation in cartilage
matrix has never been demonstrated directly.
Here, we use synchrotron-based X-ray fluorescence imaging (XFI) to detail the
distribution of total sulfur and sulfate esters in developing cartilage of
zebrafish. Our quantitative analyses of these images demonstrate that total
sulfur and sulfate esters decrease in cartilage matrix as it differentiates,
suggesting a functional link between sulfur content of cartilage matrix and the
differentiation of resident cells (chondrocytes). Supporting this hypothesis, we
find that sulfate esters are decreased in cartilage of a proteoglycan synthesis
mutant, which has precocious chondrocyte differentiation. Surprisingly, total
sulfur in this mutant was not affected, suggesting that sulfur is distributed in
an alternative chemical form when cartilage proteoglycan production is below
normal. The relevance of these findings to human osteoarthritis is currently
under investigation.
64 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
The actin binding protein profilin controls soma-germline interactions in the
Drosophila testes
Michael J. Fairchild & Guy Tanentzapf
University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC,
V6T 1Z3
Gametogenesis requires sustained cooperation between soma and germline
cells. While the signaling events between these cells is well characterized, less
is known about the cell biological processes that establish this close association
of soma and germline. To better understand the morphogenetic events that
facilitate soma-germline association we undertook a soma specific RNAi
knockdown screen. This screen identified chickadee, the Drosophila homologue
of the actin binding protein Profilin, as being essential for germline
encapsulation. Though Profilin deficient somatic cells were found in contact
with the germline, we found that many germline cells were not encapsulated,
consequently forming large germline tumors. We show that that this may be
due in part to Profilin deficient somatic cells having defects in MapK signaling
which controls germline encapsulation. Moreover, we show somatic Profilin
clones are not maintained as stem cells within the niche. Our work identifies
intriguing links between the morphogenetic events that occur during the early
phases of spermatogenesis and subsequent cell signaling between the soma and
germline.
65 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Intracellular localization and regulation of Gelatinase A in zebrafish skeletal
muscle
Fallata, AM and Crawford, BD
Department of Biology, University of New Brunswick, Fredericton, New
Brunswick, E3B 5A3
Matrix metalloproteinase (MMPs) are zinc-dependent proteases that play
fundamental roles in many physiological and pathological processes. MMPs are
known for being secreted proteins that function in extracellular matrix
remodleing. However, recent work has shown that MMPs may also function
intracellularly. MMP-2 (Gelatinase A) has been detected intracellularly in rat
cardiac myocytes, and it is implicated in the degradation of sarcomeric
proteins under conditions of oxidative stress. In addition, MMP-2 activity is
altered by phosphorylation, which is inconsistent with a strictly extracellular
function. We sought to determine if the intracellular localization of this
protease is a general feature of striated muscle, and if so, to elucidate the
role(s) it may play in muscle cell development and physiology. We have
confirmed the localization of zebrafish Mmp2 in skeletal muscle by confocal
microscopy and immunofluorescence of ultrathin cryosections. I am now
investigating the possibility of Mmp2 phosphorylation, and exploring roles
Mmp2 may play in muscle cell physiology by comparing Mmp2 localization and
phosphorylation status in normal and hypertrophic muscle, as well as between
growing and mature zebrafish.
66 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Rac1 is critical to cardiomyocyte polarity and embryonic heart development
Carmen Leung1,2, Xiangru Lu1, Murong Liu3, Derek Little1, Qingping Feng1,3
1
Department of Physiology & Pharmacology, Schulich School of Medicine &
Dentistry
2
Collaborative Program in Developmental Biology, 3Lawson Health Research
Institute, The University of Western Ontario, London, Ontario,
Congenital heart defects (CHDs) are the leading cause of death from congenital
malformations in the first year of life. Thus, a further understanding of the
mechanisms underlying CHDs is crucial. The second heart field (SHF) is a
progenitor cell population that migrates to contribute to the right ventricle
(RV), ventricular septum and outflow tract of the developing heart. Rac1 is a
small signaling G-protein that acts as a pleiotropic effector of numerous
cellular processes including actin cytoskeleton organization, migration and
survival. However, the role of Rac1 specifically in SHF progenitors during heart
development remains elusive. We hypothesized that Rac1 signaling in the SHF
regulates cardiomyocyte polarity, chamber septation and right ventricle (RV)
development during embryogenesis. To test this hypothesis, mice with a SHFspecific deletion of Rac1 (Rac1SHF) were generated. At postnatal day one, all
Rac1SHF mice exhibited extensive CHDs including ventricular septal defects,
atrial septal defects, thin RV myocardium with defective trabeculation and
bifid cardiac apex, a rare heart defect. Fate-mapping analysis showed that SHF
contribution to the interventricular septum and RV was deficient in Rac1SHF
hearts. In addition, a 3-fold increase in apoptosis was observed in the RV
myocardium and cardiac septum of Rac1SHF hearts with decreased expression
of GATA4, Tbx5, Nkx2.5 and Hand2 transcription factors. Furthermore, the RV
myocardium of Rac1SHF mice displayed defects in cardiomyocyte polarity and
actin organization with decreased expression of WAVE and Arp2/3, leading to
decreased migratory ability. Expression of Scrib, a core protein in planar cell
polarity, was lost in Rac1SHF hearts. Additionally, Rac1 deficient neonatal
cardiomyocytes displayed defects in cell projections, lamellipodia formation
and cell elongation. We conclude that a Rac1 deficiency in the SHF leads to
complete penetrance of CHDs. Our study demonstrates for the first time that
Rac1 signaling in the SHF is a critical regulator of cardiomyocyte polarity,
cardiac septation and RV development during embryogenesis.
67 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Lineage Tracing of Neuronal Progenitor Cells Expressing dlx Genes in the
Zebrafish Brain
Shengrui Feng, Cynthia Solek, Elyssa Mahoney, Marc Ekker
Center for Advanced Research in Environmental Genomics, Department of
Biology, University of Ottawa, Ottawa, ON, K1N 6N5
The dlx homeobox genes are essential for forebrain GABAergic interneuron
differentiation and migration. In order to understand the fate of neuronal
progenitor cells expressing dlx genes in the brain, we produced lines of
transgenic fish expressing the Cre-ERT2 recombinase driven by regulatory
elements from either the dlx1a/dlx2a locus or the dlx5a/dlx6a locus. Cre-ERT2
expression in these fish faithfully recapitulates that of dlx genes in the
forebrain. These fish were mated with ubi:Switch reporter fish that express a
loxP-flanked GFP gene followed by mCherry, driven by the ubiquitin promoter.
Upon tamoxifen treatment, the double transgenic fish express mCherry in dlxexpressing cells. Fate mapping of mCherry+ cells in double transgenic fish
demonstrated that GABAergic neurons are labeled. We are tracing lineages of
different subpopulations of GABAergic neurons by varying the time of Cre-ERT2
induction. We are also comparing lineages of cells expressing dlx1a/dlx2a and
dlx5a/dlx6a to determine whether different dlx genes contribute to the
development of different subpopulations of GABAergic neurons. Furthermore,
as zebrafish produce new neurons throughout life, we are examining the role of
dlx genes during adult neurogenesis and during regeneration, which may
provide new insights into the neuro-regenerative abilities of teleost fish and
mammals.
68 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Roles Mcl-1 and Bcl-xL in nervous system development
Lauren Fogarty1, Hiliary Martin1, Beibei Song1, S. M. Mahmudul Hasan1, Jieying
Xiong1, Joseph T. Opferman2, Lothar Hennighausen3, Jacqueline Vanderluit1
1
Faculty of Medicine, Memorial University of Newfoundland, 300 Prince Phillip
Dr. St John’s, NL, Canada, A1B 3V6
2
St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN,
USA, 38105-3678
3
Laboratory of Genetics and Physiology, NIDDK, NIH, Bethesda, MD, USA 20892
During neurogenesis of the embryonic nervous system, cells transition from
neural stem cells to neural progenitors, to neuroblasts to differentiated
neurons. Changes in cell survival signaling are still poorly understood through
these transitions. We have examined the role of anti-apoptotic Bcl-2 proteins,
Mcl-1 and Bcl-xL in promoting survival as cells progress through the stages of
neurogenesis. Nestin mediated conditional deletion of Mcl-1 or Bcl-xL in the
mouse embryonic nervous system results in extensive cell death in specific cell
populations within the spinal cord, hindbrain and cortex at different times. In
the Mcl-1 knockout, apoptosis begins at embryonic day 10 (E10), the start of
neurogenesis within proliferating cell populations. In the Bcl-xL knockout,
apoptosis is observed in post mitotic cells at E11 in the spinal cord and
hindbrain but isn’t observed in the cortex until E17 as neurogenesis is
concluding. To determine how both Mcl-1 and Bcl-xL promote cell survival
during neurogenesis, qPCR and in situ hybridization were used to examine the
expression profiles of the pro-apoptotic Bcl-2 family members. This study
demonstrates the distinct requirements of survival factors, Mcl-1 and Bcl-xL
through the different stages of neurogenesis within the developing mouse
embryo.
69 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
New Tools for the Study of Limb Development
Claudia Gentile, Rushikesh Sheth, and Marie Kmita
Institut de recherches cliniques de Montréal, 110 Avenue des Pins Ouest,
Montréal, QC, H2W 1R7
The developing limb is a useful model system to study developmental
processes, as illustrated with the numerous general principles discovered by
studying limb development. Limb morphogenesis is a very dynamic process and
the early bud gets rapidly subdivided into two domains, a proximal and a distal
domain. While the loxP-Cre recombination system allows for limb-specific gene
modification in mouse embryos, there is so far no Cre line specific for either
the proximal or distal bud domain. Here, I report on the generation of such Cre
lines. We have identified both a proximal and distal enhancer element and
used them to generate, respectively, a proximal-specific and distal-specific Cre
transgene. Each construct was designed to express either the Cre or CreERT2,
according to the needs. CreERT2 is a Tamoxifen inducible version of the Cre
gene, which allows for time-specific Cre activity. Finally, these transgenes
carries fluorescent reporter genes to monitor cells expressing Cre/CreERT2. We
believe, these mouse lines will be very useful for the developmental biology
community working on limb development.
70 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Investigating stem cell mitosis in vivo by live-imaging in C. elegans
Abigail R. Gerhold1, Paul S. Maddox2, Jean-Claude Labbé1
1
Institut de recherché en immunologie et en cancérologie (IRIC), Université de
Montréal, QC, Canada.
2
Department of Biology, University of North Carolina, Chapel Hill, NC, USA.
Accurate segregation of the replicated genome is an essential step in the
production of genetically identical daughter cells during mitosis. The fidelity of
chromosome segregation relies upon the efficacy of chromosome congression
and the activity of the spindle assembly checkpoint. The duration of
congression and the strength of the spindle assembly checkpoint vary between
cell types and organisms. The basis for these differences is poorly understood.
Importantly, how these fundamental mitotic processes are influenced by the
physiological context in which a cell divides has not been established. We have
developed a novel live-imaging strategy that uses the germ line stem cells of
the genetically tractable model organism Caenorhabditis elegans to investigate
key features of stem cell mitosis in intact animals. In particular, we are
examining how the duration of congression and the activity of the spindle
assembly checkpoint are affected by the developmental transition between
stem cell expansion during larval development and stem cell maintenance in
adults, and by food availability. We found that the duration of congression is
reduced during stem cell expansion and increased by dietary restriction. We
are investigating these findings to understand how physiological factors
influence fundamental steps in mitotic progression.
71 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Essential role for the GATA6 trascription factor in heart development
Lara Gharibeh, Hiba Komati and Mona Nemer
Department of Biochemistry, Microbiology and Immunology, Faculty of
Medicine, University of Ottawa, ON
A large number of transcription factors (TF) and complex molecular regulatory
networks control heart morphogenesis. Deviations due to environmental or
genetic factors result in congenital heart defects (CHD) defined as familial
inherited diseases with incomplete penetrance. Mutations in TFs GATA4,5,6,
are associated with many types of CHD. Consistent with a critical role in
development, Gata4 and Gata6 null mice are embryonic lethal at E8.5and E5.5
respectively. Gata4 haploinsufficient mice display several cardiac defects and
Gata5 null mice have bicuspid aortic valves. No overt cardiac abnormalities
have been reported for Gata6+/- mice, however, double Gata4+/-Gata6+/- and
Gata5+/-Gata6+/- mice die embryonically or perinatally and display multiple
heart defects. Together with earlier finding of transcriptional cooperation
among these GATA factors, the phenotypes of the double heterozygous mice
prompted a reexamination of the hearts of Gata6+/- mice for the presence of
subtle structural or functional abnormalities. The results uncovered significant
structural valve defects as well as conduction system abnormalities in Gata6+/mice. The results indicate that GATA6 haploinsufficiency leads to CHD and that
Gata6 is an important regulator of valve formation and heart morphogenesis.
72 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
ATRX deficiency in the development and progression of glioma
Hannah Goldberg1,2,3, Kristin D. Kernohan1,2,3, Nathalie G. Bérubé1,2,3
1
University of Western Ontario, Departments of Paediatrics and Biochemistry
Children’s Health Research Institute
3
Lawson Health Research Institute
2
Gliomas are tumours that arise from glial cells within the central nervous
system (CNS) and account for approximately 30% of all CNS neoplasms.
Emerging evidence indicates that unique molecular and genetic footprints
define glioma subtypes. The ATRX gene is commonly mutated in a subset of
gliomas across all tumour grades and within both the paediatric and adult
populations. ATRX is a chromatin remodeling protein that is essential for
proper neural development. Conditional deletion of Atrx in the mouse
forebrain starting at embryonic day 8.5 leads to elevated replication stress and
p53-mediated neuronal cell death. Transcriptional profiling of control and Atrxnull neonatal mouse forebrains revealed increased expression of genes involved
in cellular phenotypes linked to glioma development. Moreover, preliminary in
vitro data shows that concurrent inactivation of Atrx and p53 in cultured
mouse neuroprogenitor cells leads to genomic instability and increased
proliferative capacity. These data suggest that Atrx deficiency in the
developing brain can induce oncogenic signaling pathways predicted to
promote genomic instability and tumorigenesis when combined with p53
mutations.
73 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Regulation of cortical loading of the scaffold protein ANI-2 during syncytial
formation of the C. elegans germline
Eugénie Goupil and Jean-Claude Labbé
Institut de recherche en immunologie et en cancérologie (IRIC), Université de
Montréal, QC, Canada.
Cytokinesis is the last step required to separate the daughter cells after
mitosis. In the germline of most animals, cytokinesis often fails, leading to the
formation of a stable intercellular bridge, and eventually, a syncytium. ANI-2, a
non-canonical form of the scaffold protein Anillin, is expressed in the germline
precursor cell, P4 during C. elegans embryogenesis. When P4 divides into Z2 and
Z3, ANI-2 is redistributed between the daughter cells intercellular bridge and
remains at the syncytial opening throughout gonad formation. ANI-2’s presence
is essential, its depletion causing a loss of the intercellular bridge, leading to
severe gonad disorganization and sterility. Therefore, ANI-2’s presence at the
P4 cortex may be the primary event leading to intercellular bridge assembly
and stabilization. To test this, measured the cortical loading of ANI-2 in P4, and
its redistribution to Z2 and Z3, after depletion by RNA interference of
contractility regulators and genes whose depletion was reported to cause a
phenotype similar to that observed after loss of ani-2. Our results suggest that
ANI-2 loading to the P4 cortex is one of the primary events leading to the
formation of the intercellular bridge between Z2 and Z3, revealing its
importance in syncytium formation during C. elegans germline development.
74 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
The kinase module of the Mediator complex regulates EGFR signaling to
influence cell fate decisions in C. elegans
Jennifer M. Grants1,2, Lisa T.L. Ying2, Akinori Yoda3, Hideyuki Okano3, Charlotte
C. You2, Shirley Y. Chen2, Hitoshi Sawa3, and Stefan Taubert1,2
1
Department of Medical Genetics, University of British Columbia, Vancouver,
Canada
2
Centre for Molecular Medicine and Therapeutics, Vancouver, Canada
3
Division of Neuroanatomy, Osaka University Graduate School of Medicine,
Osaka, Japan
The Mediator complex is a conserved transcriptional coregulator that acts in
diverse signaling pathways. Individual Mediator subunits have distinct effects
on signaling pathways, but the mechanisms for this specificity are poorly
understood. We show that the four subunits that compose Mediator’s kinase
module, cyclin dependent kinase 8 (CDK8), cyclin C, MED12, and MED13,
negatively regulate epidermal growth factor receptor (EGFR) signalingdependent cell fate decisions in the Caenorhabditis elegans vulva. Genetically,
the kinase module acts downstream of the EGF Receptor, as loss of the kinase
module suppresses a cell fate error caused by an EGFR reduction-of-function
allele. We find that the kinase module is a corepressor for a conserved Etsfamily transcription factor (TF) that is a terminal effector in the pathway, as
loss of the kinase module enhances a cell fate error caused by reduction-offunction of this Ets TF. In addition, loss of the kinase module suppresses a cell
fate error caused by loss of another Mediator subunit, SUR2, a coactivator of
Ets-driven transcription. Together, this suggests novel epistasis between
Mediator subunits regulating a common TF to fine-tune the output of EGF
signaling. These findings agree with recent reports implicating loss of MED12 in
tumor cell resistance to BRAF inhibitor chemotherapy.
75 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Maintenance of muscle integrity by Hedgehog signaling
Peng Huang1,2 and Alex Schier2
1
2
Department of Biochemistry and Molecular Biology, University of Calgary
Department of Molecular Cellular Biology, Harvard University
Muscular dystrophy refers to a group of hereditary muscle diseases in which the
muscle forms normally but progressively degenerates, leading to loss of muscle
function. The development of therapeutic approaches for muscular dystrophy
depends on the isolation of genes and cellular components that normally
protect against muscular dystrophy. However, our understanding of how muscle
integrity is maintained remains rudimentary. We recently discovered that
mutations in Hh signaling and muscular dystrophy genes display genetic
interactions. Moreover, activation of Hedgehog signaling is essential for
maintaining muscle integrity. Here I will discuss several approaches we took to
dissect the cellular and molecular basis of muscle maintenance by Hedgehog
signaling.
76 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Neurodevelopmental exposure to bisphenol a induces locomotor
hyperactivity and perturbs hypothalamic neurogenesis in zebrafish
K Ibhazehiebo2 CD Kinch1, DM Kurrasch2
1
2
Department of Biological Sciences, University of Calgary, Calgary, AB
Department of Medical Genetics, University of Calgary, Calgary, AB
A strong causative relationship has been established linking ubiquitous
environmental contaminant exposure to various cognitive and behavioral
disorders. However, how this environmental challenges leads to altered
behavior later in life is poorly understood. Here, we study the effect of
Bisphenol A (BPA) on locomotor behavior in zebrafish (ZF) and show that
neurodevelopmental exposure to low dose BPA led to significant changes in
early life-stage behavior via the CYP19a1b pathway, especially during the
period of neurogenesis. Also, we examined the effect of BPA on the neurogenic
period of the hypothalamus. Given that hypothalamic progenitor cells express
aromatase, we reasoned that estrogenic BPA might influence the maintenance
of hypothalamic progenitors and affect the timing of neuronal birth, ultimately
perturbing circuitry establishment of key neuroendocrine pathways. To test this
hypothesis, we exposed embryonic ZF to BPA at key developmental time points
and examined the onset and duration of hypothalamic neurogenesis using
molecular markers. BPA exposure resulted in a lengthened hypothalamic
neurogenic period with an overall increase in the number of hypothalamic
neurons. Understanding the molecular consequences of environmental toxins
on brain development during these initial, crucial stages may shed insight into
the underlying etiology of a variety of neurological disorders.
77 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Role of integrin-linked kinase on epidermal keratinocyte survival
Michelle Im, TS Irvine, and Lina Dagnino
Department of Physiology and Pharmacology, Collaborative Program of
Developmental Biology, Children’s Health Research Institute and Lawson Health
Research Institute, University of Western Ontario, London, Ontario
Integrin-linked kinase (ILK) is a ubiquitous scaffold protein that mediates
cellular responses to integrin stimulation by extracellular matrix proteins. Mice
with inactivation of the Ilk gene in squamous epithelia display defects in skin
regeneration after injury, failure to thrive, and perinatal death. ILK-deficient
epidermis exhibits reduced adhesion to the basement membrane and impaired
hair follicle morphogenesis. In culture, ILK-deficient keratinocytes fail to
attach and spread efficiently, and demonstrate decreased survival. We now
show that ILK-deficient keratinocytes exhibit lower proliferative capacity and
increased apoptosis in the absence or presence of growth factors. This reduced
viability appears to be independent of the AKT pathway, as ILK-deficient cells
exhibit normal levels of active, phosphorylated AKT. They do, however, display
higher levels of cleaved Caspase-3 and PARP, both associated with caspasedependent programmed cell death. We have also observed an increase in
γH2A.X, a marker of DNA double-strand breaks, which is also associated with
increased levels of reactive oxygen species (ROS) in these cells. Thus,
increased susceptibility to DNA damage due an increase in ROS may lead to
decreased cell survival. Our findings underline a distinct, novel role for ILK in
promoting keratinocyte survival and a normal REDOX state. Supported with
funds from CIHR.
78 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
A novel RhoG-ILK/ELMO2-Rac1 pathway stabilizes microtubules.
Bradley C. Jackson and Lina Dagnino
Department of Physiology and Pharmacology, Children’s Health Research
Institute and Lawson Health Research Institute, University of Western Ontario,
London, ON, Canada.
Integrin-linked kinase (ILK) is a widely expressed scaffold protein important for
cell adhesion, migration, and phagocytosis. ILK and its interacting partner,
Engulfment and Motility 2 (ELMO2), may also modulate microtubule dynamics.
We investigated whether ILK and ELMO2 could stabilize microtubules in the
presence of 5 µM colchicine. After 60 minutes of drug treatment, 20.7±1.2% of
cells had intact microtubules. Expression of exogenous ILK or ELMO2 increased
the proportion of cells with intact microtubules to 49.0±1.5% or 53.6±1.2%,
respectively. Further, 62.3±1.5% of cells expressing both ILK and ELMO2 had
intact microtubules after treatment. To determine whether ILK participates in
microtubule dynamics, we analyzed ILK-deficient cells and observed that only
4.3±0.9% had intact microtubules after colchicine treatment. Exogenous ELMO2
had no effect on microtubule stability in ILK-deficient cells. Since RhoG binds
to ELMO2/ILK complexes we investigated whether RhoG could affect
microtubule stability and found that 51.3±2.3% of cells expressing exogenous
RhoG had intact microtubules after colchicine treatment. Since RhoG
interaction with ELMO can induce Rac1 activation we investigated whether
Rac1 could affect microtubule stability and found that 49.3±1.9% of cells
expressing Rac1 had intact microtubules after colchicine treatment. These
results support a novel role for a RhoG-ILK/ELMO2-Rac1 pathway in maintaining
microtubule stability.
79 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
LKB1/PAR-4 regulation of signaling C. elegans dauer germline quiescence
Kadekar P, Narbonne P, Roy R
Department of Biology, DBRI, McGill University, Montreal, Quebec H3A 1B1
C. elegans larvae undergo a global developmental arrest following the
execution of a diapause like state called ‘dauer’ in response to harsh growth
conditions. The C. elegans orthologs of both LKB1 (PAR-4) and AMPK are
required together to establish quiescence in the dauer germline although LKB1
may play an AMPK-independent role in mediating this process. LKB1 affects
actin enrichment at the rachis adjacent cell membrane in the dauer germ cells
as compared to the L4 proliferating germline where actin is present around all
the cell membranes. This rearrangement of the actin cytoskeleton toward the
rachis may affect observed cellular localization of key proteins including ANI-2
and GLP-1 (Notch receptor). We observe that over the course of dauer
diapause, GLP-1 undergoes subcellular re-localization from the membrane to
the rachis. In the hyperplasic dauer germline of an AMPK or in PAR-4 mutants,
GLP-1 is still present around the membrane of the GSCs and fails to re-localize
to the rachis and may therefore be associated with the observed germline
hyperplasia in these mutants. We are currently studying how this LKB1mediated actin rearrangement may contribute to the re-localization of GLP-1
to establish germline quiescence in response to harsh growth conditions.
80 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Global genomic survey to investigate the role of AMPK in germline stem cell
quiescence in C. elegans dauer
Anna Kazanets and Richard Roy
Department of Biology, 1205 avenue Docteur Penfield, McGill University,
Montréal, QC, H3A 1B1
In response to adverse conditions, C. elegans can enter an alternative
developmental state called dauer. In this state the larva undergoes several
changes in order to conserve energy and withstand environmental stress. One
such change occurs in the germline, where the germline stem cells (GSC) arrest
their mitotic divisions and remain quiescent for the duration of this stage.
Previous studies have identified the catalytic subunit of AMP-activated protein
kinase (AMPK), aak-2, to be necessary in establishing this cell cycle quiescence.
The aak-2 mutants exhibit pronounced hyperplasia compared to the normal
dauer, however the molecular mechanism through which AMPK controls the
GSC proliferation remains unclear. To address this question and identify
potential AMPK targets involved in the GSC quiescence, we conducted a
genome-wide AMPK/aak-2 RNAi suppressor screen for candidates that rescue
the aak-2-induced hyperplasia. After screening 18,000 genes, we have
identified several candidates, which we further categorized into gene ontology
groups. Of particular interest are ain-2 and alg-1, which are critical players in
miRNA RISC complex function and are necessary for miRNA-dependent gene
silencing. We are currently investigating how genes in the miRNA and in the
other gene families are involved in controlling AMPK-dependent GSC quiescence
in dauer.
81 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Transcriptional regulation and function of Hoxa11: a role for antisense
transcription
Kherdjemil Y1, De Martino G1, Roselló-Díez A2, Dumouchel A1, Torres M2, Sheth
R1 and Kmita M1
1
Genetics and development unit, Institut de Recherches Cliniques de Montréal,
110 avenue des Pins Ouest, H2W1R7, Montréal, Québec, Canada
2
Departamento de Desarrollo y Reparación Cardiovascular, Centro Nacional de
Investigaciones Cardiovasculares, Madrid E-28029, Spain
Limb development requires the function of genes from the HoxA and HoxD
clusters. These genes are expressed in a nested fashion along the proximaldistal axis, with patterns collinear with the gene order on the chromosome. We
recently showed that HoxA expression in distal limb relies on several remote
transcriptional enhancers that physically contact Hoxa10 and Hoxa13
promoters. Strikingly, Hoxa11, which is located in between Hoxa10 and
Hoxa13, is not expressed in the distal limb, i.e. the regulation of Hoxa11 does
not follow the classical “collinearity” rule. Using a series of targeted
rearrangements at the Hoxa11 locus, we found that the proximal restriction of
Hoxa11 is linked to some particularities of the Hoxa11 gene. Previous work
uncovered the existence of Hoxa11 antisense RNAs (lnca11) in the distal limb.
We found that these lnca11 are under the control of an enhancer located in
Hoxa11 intron, whose activity relies on HOXA13 and HOXD13, two Hox proteins
specifically expressed in the distal limb. Based on our data, we propose a
model whereby HOXA13 and HOXD13 restrict Hoxa11 expression to the proximal
limb by triggering Hoxa11 antisense transcription. The functional significance
of this complex regulation will be discussed.
82 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Molecular mechanism of egl-15/FGFR and ina-1/α-integrin regulation of
pharyngeal gland cell migration in Caenorhabditis elegans
S.R. Kim, W. Raharjo, J. Kormish
Biological Sciences, University of Manitoba, Winnipeg, MB, Canada.
Caenorhabditis elegans is a powerful tool to study cellular migration and
morphogenesis in organ development. During pharynx development, the dorsal
gland cell, g1p, is born in the anterior aspect of the pharyngeal primordium,
and undergoes a form of morphogenesis called retrograde extension. When
morphogenesis is complete, the cell body is located in the posterior pharynx
and a cytoplasmic extension is left behind the migratory path. egl-15, the
single Fibroblast Growth Factor Receptor (FGFR) in C. elegans, and ina-1, one
of two α-integrin receptors, are required for the proper migration of g1p cell.
Mutations in either egl-15 or ina-1 show similar gland cell over-migration
defects where the gland cell body migrates past the terminal bulb and is
located in proximity of the intestine. The kinase domain of EGL-15 has been
found to be significant for migration and transgenic rescue strategies are being
used to determine the tissue of EGL-15 function. Epistasis experiments are
being used to determine if egl-15 and ina-1 are functioning in the same
pathway to regulate gland cell migration.
83 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
LGN regulates asymmetric cell divisions by controlling mitotic spindle
orientation in the developing mouse retina
Marine Lacomme1, Basile Tarchini1, Camille Boudreau-Pinsonneault1 and Michel
Cayouette1,2,3
1
Cellular Neurobiology Research Unit, Institut de recherches cliniques de
Montréal, Montréal, QC
2
Department of Medicine, Université de Montréal, Montréal, QC
3
Department of Anatomy and Cell Biology, McGill University, Montreal, QC
Cell diversification in multicellular organisms depends, at least in part, on
asymmetric cell divisions, which give rise to daughter cells with different
identities. Intrinsically, asymmetric cell divisions can be generated by altering
the orientation of the mitotic spindle relative to polarized fate determinants,
which are in turn asymmetrically inherited by the daughter cells. While the
molecular mechanisms controlling division orientation are well established in
invertebrates, they remain largely unknown in mammalian neural progenitors.
Here we used the mouse retina as a model system to study the role of the
GoLoco domain protein LGN, which in flies regulates division orientation by
linking the microtubule-binding protein NuMA with the heterotrimeric protein
Gai at the cell cortex. Our analysis revealed that loss of LGN significantly
reduces apico-basal divisions of retinal progenitor cell. Consequently, analysis
of individual retinal progenitor cell lineages revealed a drastic increase in
symmetric terminal divisions producing two photoreceptors, at the expense of
asymmetric terminal divisions producing a photoreceptor and a bipolar cell.
These results show that LGN is required in retinal progenitor cells to undergo
apico-basal asymmetric divisions and establish a direct link between division
orientation and cell fate in the developing mouse retina.
84 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Regulation of actinodin1 via tissue specific cis-acting regulatory elements
R. Lalonde, D. Moses, N.Cornell, J .Zhang, M.-A. Akimenko
Department of Biology, University of Ottawa, Ontario
The fin-to-limb transition is regarded as a highly important evolutionary step in
the colonization and diversification of all land species. We previously identified
a fish-specific gene family named actinodin (and) coding for structural proteins
crucial for the formation of fin fibres known as actinotrichia. Interestingly, this
gene family is absent from all tetrapod genomes. Using a fluorescent reporter
transgenic approach, we have identified two tissue specific cis-acting
regulatory elements (CREs) upstream of the and1 gene responsible for reporter
expression in the epithelial cells and the migrating mesenchymal cells in the
median and pectoral fin fold. To assess the functionality of these CREs in
higher vertebrates we have also produced LacZ reporter mouse transgenic
lines. Interestingly, LacZ expression is only observed within the epithelial cells
of the developing mouse limbs suggesting that the activator proteins
responsible for mesenchymal cell expression have been lost during evolution.
With these results, one can hypothesize on the evolution of the actinodin gene
family and the molecular changes which occurred during the fin-to-limb
transition.
85 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Biochemical characterization of zebrafish Parla and Parlb
M. Lavictoire, S. Noble, R. Godoy and M. Ekker
Department of Biology, University of Ottawa, ON
PARL is an intramembrane serine protease of the rhomboid family. Human PARL
has been linked mitochondrial regulation and Parkinson's disease. In teleost
fish, and more specifically zebrafish, there are two parl paralogs, parla and
parlb. We previously reported that morpholino-mediated knockdown of both
parla and palrb significantly increases mortality in zebrafish larvae and
surviving embryos show impaired dopaminergic neuron patterning in the ventral
diencephalon. Injection of human PARL but not catalytically inactive PARL is
able to rescue this phenotype suggesting similarity in function between human
and zebra fish Parl. Human PARL undergoes two cleavage events. The first,
alpha-cleavage is constitutive and releases the mitochondrial localization
signal. The second, beta-cleavage occurs at a region highly conserved in
mammals and releases a small peptide known as the beta peptide. Mutation of
this cleavage event has been linked to Parkinson's disease patients. Primary
amino acid sequence of zebrafish Parls suggests absence of the beta cleavage
site. We investigated the cleavage patterns of zebrafish Parla and Parlb
following transfection into dopaminergic MES23.5 cells. This will work will shed
light on the functional conservation of vertebrate PARLs and on the importance
of their beta-cleavage to Parkinson’s disease.
86 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Emergence of Motor Circuit Activity
Chris Law1, Michel Paquet1, and Artur Kania1,2
1
Institut de recherches cliniques de Montréal, 110 avenue des Pins Ouest,
Montréal, QC, H2W 1R7
2
Departments of Anatomy and Cell Biology, and Biology, Division of
Experimental Medicine, McGill University Montréal, QC, H3A 2B2, and Faculté
de Médecine, Université de Montréal, Montréal, QC, H3C 3J7
In the developing nervous system, ordered neuronal activity patterns can occur
even in the absence of sensory input; to investigate their development, we
have used the model system of the embryonic chicken spinal motor circuit,
focusing on limb-innervating motor neurons of the lateral motor column (LMC).
At the earliest stages of their molecular differentiation, we can detect
differences between LMC neuron subpopulations in terms of expression of
neurotransmitter receptor subunits and ion transporters; patch-clamp
recordings also reveal that LMC neuron subsets have subtly different activity
patterns, reflecting this differential expression. Assaying activity by patchclamp recording and calcium-imaging demonstrates that inhibition of nicotinic,
muscarinic or GABA-ergic activity has profound effects on motor circuit activity
during the initial stages of neuromuscular junction formation. Finally, by
analysing activity in populations of LMC neurons at different developmental
stages, we show that the asynchronous, disordered neuronal activity present at
early stages of circuit formation develops into organised, synchronous activity
evident at the stage of LMC neuron muscle innervation. We hypothesize that
the small initial differences in activity between LMC neuron subtypes, in
conjunction with synchronous activity leads to the development of near-mature
patterns of locomotor activity by perinatal ages.
87 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Defining Sox11 and Combined Sox4/Sox11 Function in the Kidney
Vicki Leggo, Michel Arsenault and Sunny Hartwig, Atlantic Veterinary College,
UPEI, Charlottetown, PEI
Congenital anomalies of the kidney and urinary tract (CAKUT) comprise a
spectrum of renal malformations and constitute one of the most frequent birth
defects in humans occurring in 1:400 live births. Members of the SoxC
subfamily (Sox4, Sox11, and Sox12) of transcription factors have been shown to
play master roles in determining neuronal mesenchymal progenitor cell fate in
a broad range of developmental processes. We have previously identified an
essential role for Sox4 during normal renal development in vivo. Conditional
abalation of Sox4 in nephron progenitor cells and their derivatives results in
reduced nephron endowment and early-onset glomerular injury, which
progresses to en-stage renal failure in mice. The role of Sox11 in the
developing kidney has not been investigated. In contrast to Sox4, which is
primarily expressed in nephron progenitor cells, Sox11 is strongly expressed in
differentiated nephrogenic structures. Using conditional Sox11 knock-out
mouse models, we will now evaluate the role of Sox11 in the developing kidney
as well as combined Sox4/Sox11 signaling in the kidney. These experiments
will characterize a critical developmental pathway providing new insights into
contributing genetic factors involved in the pathogenesis of CAKUT.
88 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
The Sonic hedgehog (Shh) signaling pathway requires ZBP1-mediated local
translation to guide commissural axons
Léa Lepelletier1, Sébastien Langlois1, Christopher Kent1, Kristy Welshhans4,
Gary Bassell5, Frédéric Charron1,2,3
1
Molecular Biology of Neural Development, Institut de recherches cliniques de
Montréal, Montréal, QC, H2W 1R7, Canada
2
Department of Medicine, Université de Montréal, Montréal, QC, H3T 1J4
3
Department of Anatomy and Cell Biology, Department of Biology, Division of
Experimental Medicine, Program in Neuroengineering, McGill University,
Montréal, QC, H3A 0G4, Canada
4
Kent State University, Kent, Ohio 44242, USA
5
Emory University School of Medicine, Atlanta, Georgia 30322, USA
In the developing spinal cord, Shh attracts commissural axons to the floorplate.
Although we know that this effect is mediated by Src-family kinases (SFK), the
effector of SFK in commissural axon guidance is unknown. We hypothesized
that ZBP1 (Zipcode-Binding Protein-1), a target of SFK which, when
phosphorylated, induces local translation of target mRNAs (such as β-Actin),
might be an effector of SFK in Shh-mediated axon guidance. We show that
translation inhibitors block Shh-mediated attraction of commissural axons,
consistent with a role for local translation in Shh-mediated axon guidance. We
also show that ZBP1 is expressed in commissural neurons. Stimulation of
commissural neurons with Shh increases phosphorylation of ZBP1 in a SFKdependent manner and leads to the accumulation of β-Actin protein.
Remarkably, when commissural neurons are presented with a Shh gradient, the
levels of β-Actin mRNA and protein are higher on the high Shh side of the
growth cone. Consistent with a role for ZBP1 in Shh-mediated axon guidance in
vivo, ZBP1 inactivation leads to commissural axon guidance defects. Moreover,
expression of a non-phosphorylatable form of ZBP1 acted as a dominant
negative and prevented Shh-mediated attraction. Therefore, ZBP1 and local
translation are important effectors of SFK in Shh-mediated commissural axon
guidance.
89 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
The planar cell polarity protein Vangl2 is essential for retinal and optic
nerve development
1,2
Vicki Leung, 1,3Alexandra Iliescu, 4Christine Jolicoeur, 3Michel Gravel, 3Sergio
Apuzzo, 5Elena Torban, 4,6Michel Cayouette, and 1,2,3Philippe Gros
1
Complex Traits Group, 2Department of Human Genetics, 3Department of
Biochemistry, McGill University; 4Cellular Neurobiology Research Unit, Institut
de recherches cliniques de Montréal
5
Department of Medicine, McGill University Health Centre
6
Faculty of Medicine, Université de Montréal
Vangl2 plays a critical role in the establishment of planar cell polarity (PCP)
and is well characterized for its role in neural tube development. Previously,
we detected expression of Vangl2 in the developing retina during late
embryogenesis, which led us to investigate the potential role of Vangl2mediated PCP signaling in retinal development. We found that Vangl2 mRNA
and protein are dynamically expressed in the developing retina, with Vangl2
expression becoming progressively restricted to the ganglion cell layer and
optic nerve as the retina matures. Specifically, the expression of Vangl2 is most
prominent in retinal ganglion cells, and their axons. Additionally, we have
found that Vangl2 is essential for retinal and optic nerve development as
Vangl2Lp/Lp mutant embryos display reduced eye size, thickening of the retina,
and optic nerve abnormalities (optic nerve hypoplasia and aberrant exit
trajectory). Notably, we identified an intraretinal axon guidance defect in
Vangl2Lp/Lp mutant embryos through which axon bundles traverse throughout
the entire retina with no specific orientation and become trapped within the
sub-retinal space. Our observations identify a novel and essential role for
Vangl2-dependent PCP signaling in the intraretinal pathfinding of RGC axons.
90 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Planarian Yorkie functions as a crucial node in stem cell maintenance and
organ patterning
Alexander Lin1,2, Bret Pearson1,2,3
Department of Molecular Genetics, University of Toronto1; Hospital for Sick
Children2, Ontario Institute for Cancer Research (OICR), Canada3
Adult stem cells (ASCs) constantly undergo cell turnover during normal
physiological conditions and injury-induced regeneration; however, the
mechanisms that regulate cell proliferation to maintain proper size and
patterning remain largely unknown. To study these processes in vivo, the
planarian (Schmidtea mediterranea) is a unique model organism since it has a
high capacity to regenerate and a high rate of cell turnover. These two distinct
abilities arise from the ubiquitous population of pluripotent ASCs, which have
well-characterized gene regulatory networks. What is less known is how
planarian ASCs maintain homeostasis and proper patterning in spite of constant
cell turnover.
Here we show that planarians use Yorkie/Yki (vertebrate YAP), the effector of
the Hippo signalling cascade, as a crucial node in controlling stem cell
proliferation and organ patterning.
The loss of yki results in an expansion of the stem cell compartment, and
derepression of Wnt expression results in an axial duplication, suggesting an
interaction with the Wnt/β-catenin signalling pathway. At the organ level,
yki(RNAi) also results in loss of excretory maintenance and patterning.
Altogether, this study has uncovered novel and pleiotropic roles for Yki in the
maintenance of stem cells, the anterior-posterior axis, and the excretory
system.
91 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
ONGLET 3
POSTER SESSION B
92 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
A-1
SESSION B / POSTER SESSION B
Wednesday, March 19th, 16h - 18 h
Loewen, Royden (Sacha) - University of Manitoba
Gland Development in the Root-Knot Nematode Meloidogyne hapla.
A-2
Maeva Luxey - Institut de recherches cliniques de Montréal (IRCM)
Mechanisms of Tbx4 action on hindlimb development
A-3
Alexa Mariotti - Concordia University
Aurora B regulation of Anillin localization and polarity
A-4
Alexandre Mayran - Institut de recherches cliniques de Montréal (IRCM)
Epigenetic reprogramming of a differentiating cell by expression of the
selector gene Pax7, acting as a pioneer factor
A-5
Stephanie McMillan - University of Ottawa
Androgens and a second wave of angiogenesis are required for the growth
and regeneration of sexually dimorphic breeding tubercles on male
zebrafish pectoral fins
A-6
Meg Mendoza - The Hospital for Sick Children
Investigating the role for Tmem14a in planar cell polarity signaling,
development and disease
A-7
Jassy Meng - McGill University
Dynein heavy chain antagonizes LET-23 EGFR-mediated vulva induction in
C. elegans
A-8
Patrick Narbonne - Institut de recherche en immunologie et en
Cancérologie (IRIC)
Insulin signaling couples germline stem cell activity to oocyte needs in
aging C. elegans adults
A-9
Stephen Nemec - Institut de recherches cliniques de Montréal (IRCM)
Characterizing the role of Pitx1 and Tbx4 transcription factor genes in
mouse hindlimb patterning
A-10 Lauryl Nutter - The Hospital for Sick Children
NorCOMM2 – High-throughput knockout mouse production and
phenotyping
A-11 Marie-Hélène Ouellette - Université du Québec à Montréal (UQAM)
Study of rga-7 function in hypodermal cells during embryonic elongation
in Caenorhabditis elegans
93 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
A-12 Adam Packard - Columbia University
Mitosis-associated cell dispersal drives epithelial cell rearrangements
within the branching ureteric bud
A-13 Audrey Pelletier - Institut de recherches cliniques de Montréal (IRCM)
Molecular mechanisms of Pax7 for differentiation of POMC cells
A-14 Nicolas Pilon - Université du Québec à Montréal (UQAM)
TashT is a novel mouse model that phenocopies both the variable
penetrance and male sex-bias of Hirschsprung’s disease
A-15 Katherine Rabicki - University of Western Ontario
CTCF is critical for hindlimb development
A-16 Alexia Rabilotta Faure - Institut de recherche en immunologie et
en cancérologie (IRIC)
C. elegans as a model to study stem cell niche behavior during
development
A-17 Ayus Ranawade - McMaster University
Transcriptomics approach to understanding the role of Wnt signaling in
C. elegans development
A-18 Qamber Raza - McMaster University
Extension of Filopodia and Lamellopodia requires Robo/Slit and
Frazzled/Netrin signalling during Drosophila heart morphogenesis
A-19 Johanne Robitaille - Dalhousie University
Effect of FZD4 on development of severe retinopathy of prematurity
using the ocular ischemic mouse model
A-20 Richard Roy - McGill University
AMPK buffers adverse epigenetic change and consequent
transgenerational reproductive defects following acute nutrient/energy
stress
A-21 Aimée Ryan - McGill University
CPE-sensitive claudins are essential for neural tube closure
A-22 Fadi Sader - Université de Montréal
Characterisation of ski-like and c-Myc in the TGF-β pathway during
axolotl limb regeneration
A-23 Mark Samuel - Université de Montréal
Evolution and genetics of the patella
94 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
A-24 Oraly Sanchez-Ferras - Université du Québec à Montréal (UQAM)
Induction and dorsal restriction of Paired-box 3 (Pax3) gene expression in
the caudal neuroectoderm is mediated by integration of multiple
pathways on a short neural crest enhancer
A-25 Sebastian Schmeisser - McGill University
Ectopic lipid accumulation in tissue aging and lifespan determination
A-26 Maxwell Shafer - McGill University
The role of Gata3 in prostate epithelial morphogenesis during
development
A-27 Richa Sharma - McGill University
Molecular mechanisms of renal lineage specification
A-28 Rushikesh Sheth - Institut de recherches cliniques de Montréal (IRCM)
Hoxome13: a systemic approach to understand Hox biology
A-29 Randeep Singh - University of Western Ontario
Rad23A, a ubiquitin binding protein, regulates E2F1 degradation in
keratinocyte
A-30 Skerjanc, Ilona S. - University of Ottawa
Inhibition of GSK3B enhances embryonic stem cell-derived skeletal
myogenesis
A-31 Christopher Small - University of New Brunswick
Comparing lumen size and vascular development between diploid and
triploid zebrafish
A-32 Audrey Mideum Song - McGill University
UBC-25 promotes Ras/MAPK signaling to regulate oocyte growth and
embryonic morphogenesis in C. elegans
A-33 Rodolphe Soret - Université du Québec à Montréal (UQAM)
A new mechanism for Hirschsprung's disease involving the self-modulation
of neural crest cell microenvironment
A-34 Martin Srayko - University of Alberta
The memi gene family is required for female meiosis II in the C. elegans
embryo
A-35 Katie Stewart - McGill University
Modulation of programmed cell death by the inhibitor of apoptosis
proteins is required for appropriate urogenital system morphogenesis
95 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
A-36 Alexandra Sull - University of Western Ontario
The role of Shroom3 in kidney development.
A-37 Judith Sull - University of Western Ontario
Analyzing cardiac function in Xenopus embryos using a novel imaging
system
A-38 Margaret Man-Ger Sun - University of Western Ontario
Liver X Receptor activation delays chondrocyte hypertrophy during
endochondral bone growth
A-39 Nora Szabo - Institut de recherches cliniques de Montréal (IRCM)
A role for the transcription factor Lmx1b in pain modality discrimination
A-40 Nobuhiko Tachibana - University of Calgary
Pten phosphatase regulates amacrine cell differentiation in the
developing retina
A-41 Aboubacrine Touré - Université du Québec à Montréal (UQAM)
The TashT locus genetically interacts with other Hirschsprung’s diseaseassociated loci in a male-biased manner
A-42 Mathieu Tremblay - McGill University
GATA3 antagonizes prostate cancer progession
A-43 Éric Villard - Université de Montréal
Role of BMP and TGF-B signaling in regulating apoptosis during limb
regeneration
A-44 Étienne Vincent - Université de Montréal
Abnormal limb regeneration through inhibition of BMP signaling
A-45 Stephanie Wales - York University
Dual Specificity MAPK Phosphatases are revealed as targets of MEF2 in
skeletal and cardiac muscle
A-46 Erika Wee - McGill University
Calibration of wide-field deconvolution microscopy for quantitative
fluorescence imaging
A-47 Denise Wernike - Concordia University
Anillin (ANI-1) is required for neuroblast cytokinesis to non-autonomously
regulate epidermal morphogenesis in C. elegans embryos
96 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
A-48 Callista Yee - McGill University
Mechanisms of reactive oxygen species-mediated longevity
97 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Gland Development in the Root-Knot Nematode Meloidogyne hapla.
R.A. (Sasha) Loewen, J. Kormish
Biological Sciences, University of Manitoba, Winnipeg, MB
Root-knot nematodes (RKN) are plant parasitic nematodes that cause massive
crop loss in Canada and worldwide. RKN are adept at invading plant tissue with
secretions they produce and release from their gland cells. The collection of
proteins within these secretions, called the “secretome”, has been studied
intensely using transcriptomics and proteomics. I am studying the model RKN
Meloidogyne hapla, with a focus on the development of its highly derived gland
cells. I will be comparing the development of M. hapla’s gland cells with those
of Caenorhabditis elegans’, by looking at the role of the pharyngeal and gland
important transcription factors PHA-4, and HLH-6 respectively. I have
identified putative homologues of these transcription factors in M. hapla and
will be exploring their DNA binding sites and downstream targets in parallel on
both worms. Using chromatin immunoprecipitation followed by next generation
sequencing (ChIP-seq), I will describe the binding sites of these important
transcription factors, and their downstream targets comparatively in both
species. Understanding RKN gland development will aid in developing effective
control mechanisms to inhibit this pest in the agricultural setting.
98 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Mechanisms of Tbx4 action on hindlimb development
M.Luxey and J.Drouin
Institut de Recherches Cliniques de Montréal, Montréal, Québec, H2W 1R7
Limb development is governed by a genetic program common to all
appendages. Morphological and functional differences between forelimbs (FL)
and hindlimbs (HL) appear to result from modulation of this developmental
program. Mechanisms for specification of limb identity have focused on three
transcription factors with limb-restricted expression patterns: Pitx1 and Tbx4
that are expressed in HL, and Tbx5 expressed in FL.
Characterization of the transcriptional properties of these factors revealed that
Pitx1 acts upstream of Tbx4 and contributes to Tbx4 expression. Tbx4 and Tbx5
share a conserved transcriptional activation domain that may control limb bud
growth as Tbx5-/- mice fail to develop FLs. In addition, Tbx4 has a unique Cterminal repressor domain, the activity of which is correlated with the role of
Tbx4 in HL identity. Interestingly, the Tbx4 repressor activity appears to be
context-dependent, suggesting a role for critical corepressor(s).
We use biochemical approaches to investigate the putative Tbx4 coregulators,
in particular through the purification of protein complexes and GS/MS analyses.
Collectively, these analyses will define the gene regulatory networks and
mechanisms responsible for Tbx4 function(s) in HL development.
99 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Aurora B regulation of Anillin localization and polarity
Alexa Mariotti, Melina Jaramillo Garcia, Alisa Piekny
Department of Biology, Concordia University
Cytokinesis occurs at the end of mitosis to divide the mother cell into two
daughter cells. An actomyosin contractile ring forms at the equatorial cortex
and ingresses to pinch the cytosol and membrane in two. Cytokinesis occurs
perpendicular to the axis of asymmetry in epithelial cells with apicobasal
polarity to ensure that each daughter cell inherits apicobasal polarity.
However, how this asymmetry is maintained is not known. Anillin interacts with
numerous components of the cell division machinery, including microtubules,
and is a key regulator of cytokinesis by coordinating actomyosin contractility.
We hypothesize that Anillin is phosphorylated by Aurora B kinase to control
polarityduring cytokinesis. Aurora B complexes with the inner centromere
protein (INCENP), borealin and survivin to form the chromosomal passenger
complex (CPC), which regulates spindle assembly and cytokinesis. We found
thatAurora B phosphorylation may alter Anillin’s affinity for the cortex and/or
microtubules during cytokinesis. Furthermore, we found that myosin and Anillin
are enriched at the basal cortex of dividing MDCK cells, and inhibiting Aurora B
activity enhances the polarity of these cells. We are further investigating the
molecular requirement for Aurora B phosphorylation of Anillin in cytokinesis of
Hela and MDCK cells.
100 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Epigenetic reprogramming of a differentiating cell by expression of the
selector gene Pax7, acting as a pioneer factor
Alexandre Mayran1, Aurelio Balsalobre1, Yves Gauthier1, Jacques Drouin1
1
Laboratoire de génétique moléculaire, IRCM, 110 avenue des pins Ouest,
H2W 1R7, Montréal, Qc, Canada
Cell specific transcription of genes localized in open chromatin result from the
action of transcription factors (TF) forming the enhanceosome. However, only a
specific class of TF, called pioneer factors, are able to access highly compacted
chromatin, changing its epigenetic marks and rendering it accessible to others
TF. Tpit is the transcriptional regulator for terminal differentiation of both
POMC expressing lineages of the pituitary: the corticotropes and the
melanotropes. Pax7 has been shown to be the selector factor of one of those
lineages: the melanotropes. During development Pax7 prepares the chromatin
for Tpit action by making accessible melanotrope-specific loci. Remarkably,
expression of Pax7 in a corticotrope cell line, the AtT-20 cells, profoundly
changed chromatin marks, resulting in an altered Tpit cistrome. In particular,
marks of open/active enhancers accompanied by Tpit recruitment peaks
appeared at the vicinity of melanotrope-specific genes. We also saw the
recruitment of Ash2, a histone methyl transferase of the Trithorax chromatin
remodelling complex at those loci. I generated a population of AtT-20 cells
expressing an inducible form of Pax7. This cell model represents a useful tool
to dissect the cascade of events following Pax7’s action, and is likely to reveal
basic modes of action of pioneer factors.
101 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Androgens and a second wave of angiogenesis are required for the growth
and regeneration of sexually dimorphic breeding tubercles on male
zebrafish pectoral fins
Stephanie C. McMillan1,2 , Zhe T. Xu2 , Jing Zhang2 , Vance L. Trudeau2,4, and
Marie-Andrée Akimenko1,2,3
1
Department of Cellular and Molecular Medicine, University of Ottawa, ON, K1N
6N5, Canada
2
CAREG, 30 Marie Curie, University of Ottawa, ON, K1N 6N5, Canada
3
Department of Biology, 30 Marie Curie, University of Ottawa, ON, K1N 6N5,
Canada
Breeding tubercles (BTs), epidermal cell aggregates covered by a conical,
keratin cap, have been identified on the skin of male and female zebrafish.
However, BT clusters on the dorsal surface of pectoral fins appear only in
males upon sexual maturation. We observed that these sexually dimorphic BTs
are maintained year-round in zebrafish, through regular shedding and renewal
of the keratinized surface. Using the Tg(fli1a:EGFP) transgenic line, we showed
that, following pectoral fin amputation, BTs regenerate after the initiation of
revascularization but, concomitantly with a novel second wave of angiogenesis
that ultimately vascularizes each BT cluster. Since BT clusters are sexually
dimorphic, the effects of sex steroids on BT growth and regeneration were
investigated. We showed that androgens induce and estrogens inhibit BT
formation in intact and regenerating pectoral fins of both genders.
Furthermore, similar to males, BTs of androgen-treated females are highly
vascularized and undergo a second wave of revascularization during
regeneration. In addition, treatment of females with an angiogenesis inhibitor
impedes androgen-induced BT cluster formation suggesting that androgens
elicit pro-angiogenic effects. Overall, zebrafish pectoral fin BT growth and
regeneration requires androgens and a vast blood vessel network that naturally
occurs in males. Supported by a CIHR grant to MAA.
102 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Investigating the role for Tmem14a in planar cell polarity signaling,
development and disease
Mendoza, M and Ciruna, B
The Hospital for Sick Children, Toronto, Ontario, Canada.
The planar cell polarity (PCP) pathway controls numerous biological processes
that involve the synchronous movement and organization of cells within a
single plane of tissue. Regulation of the PCP pathway is largely attributed to a
core set of signaling molecules, such as Vangl2, which have been identified
through genetic screens with Drosophila. However, the inability of previous
screens to account for vertebrate-specific PCP –dependent morphogenetic
processes, such as primary cilia organization has brought the completeness of
the pathway into question. Recently, we identified the transmembrane protein
Tmem14a as a novel interactor of Vangl2. Initial functional analysis suggest
that Tmem14a localizes to a polarized compartment of the trans-Golgi, and
that it participates in the posterior positioning of basal bodies within the
zebrafish neural tube. Additionally, tmem14a mutants possess Golgi
fragmentations within enveloping layer cells, suggesting that Tmem14a may
play a role in Golgi structuring. Based on the localization of Tmem14a to the
Golgi and evidence of an interaction with Vangl2, we hypothesize that
Tmem14a may also function in Vangl2 trafficking. Here, we present our ongoing
studies investigating the role for Tmem14a in the trafficking of PCP signaling
components and determining how Tmem14a function contributes to Golgi
complex organization.
103 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Dynein heavy chain antagonizes LET-23 EGFR-mediated vulva induction in
C. elegans
Jassy Meng, Olga Skorobogata, & Christian E. Rocheleau
Departments of Medicine and Anatomy and Cell Biology, McGill University,
Montreal, QC
A conserved Epidermal Growth Factor Receptor (EGFR)/ Ras/ Mitogen Activated
Protein Kinase (MAPK) signaling pathway specifies vulval cell fates in C.
elegans. A complex of LIN-2 Cask/ LIN-7 Veli/ LIN-10 Mint is required for EGFR
localization to the basolateral membrane of the vulva precursor cells (VPCs),
and hence vulva development. We previously identified the late endosomal
RAB-7 GTPase as a negative regulator of EGFR signaling and strong suppressor
of the lin-2(-) Vulvaless phenotype. In a mutagenesis screen for lin-2(-)
suppressors (negative regulators that might function with RAB-7) we identified
vh22. vh22 is a temperature sensitive embryonic lethal mutation that has two
missense mutations in the dhc-1 gene. Genetic complementation and
transgenic rescue confirm that vh22 is an allele of dhc-1. Similar to a rab-7
mutation, genetic epistasis indicates that DHC-1 functions upstream or in
parallel to LET-23 EGFR and dhc-1(vh22) animals have nearly double the
number of LET-23::GFP foci in hypodermal cells suggesting a trafficking defect.
The Dynein minus-end directed microtubule motor regulates vesicular
trafficking with a number of different Rab GTPases, including RAB-7. We are
currently testing if DHC-1 functions with RAB-7 to regulate LET-23 EGFR
trafficking and/or degradation in the VPCs.
104 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Insulin signaling couples germline stem cell activity to oocyte needs in aging
C. elegans adults
Patrick Narbonne1, Jean-Claude Labbé1, Paul S. Maddox1,2
1
Institut de recherche en immunologie et en cancérologie (IRIC), Université de
Montréal, QC, Canada.
2
Department of Biology, University of North Carolina, Chapel Hill, NC, USA.
The efficiency of stem cell-dependent processes, and perhaps also stem cell
capacities, declines with age, but the mechanisms remain unclear. We use C.
elegans germline stem cells (GSCs) as model to study stem cell activity in aging
adults. In unmated hermaphrodites, GSC self-renewal and differentiation
dramatically decreases at the time when sperm is depleted. Providing
unlimited sperm by mating hermaphrodites with males significantly delayed
GSC activity decline, indicating that GSC activity is linked to sperm availability
and/or oocyte usage. We searched for conditions affecting GSC proliferation
after sperm depletion in unmated hermaphrodites and identified daf-18/PTEN
mutants, which have de-repressed insulin signaling. Unmated daf-18/PTEN
mutants maintained high self-renewal even after sperm depletion, and their
GSCs behaved similar to age-matched mated wild-type animals. Importantly,
the effects of mating and insulin de-repression were not additive. Thus, oocyte
demand must impinge on insulin signaling to regulate GSC proliferation and
differentiation activity in aging adults. Interestingly, sperm-depleted unmated
mutant hermaphrodites that constitutively layed their unfertilized oocytes also
had sustained GSC self-renewal. Our results thus demonstrate that the overaccumulation of terminally-differentiated stem cell progeny, the unfertilized
oocytes, specifically acts as the primary signal that triggers insulin
downregulation which, in turn, induces GSC quiescence.
105 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Characterizing the role of Pitx1 and Tbx4 transcription factor genes in
mouse hindlimb patterning
Stephen Nemec, Maëva Luxey and Jacques Drouin
Institut de recherches cliniques de Montréal, Montréal, QC
In tetrapods, forelimbs (FL) and hindlimbs (HL) develop complex
musculoskeletal structures within the framework of a three-segment
organization that is common both between and within species. The
musculoskeletal patterning of these segments, however, differs in correlation
with the utility of a particular limb: though all limbs consist of cartilage, bone,
muscle and tendon, the arrangement of these components depends on the
reproducible implementation of an underlying developmental program.
Genetics experiments suggest that Pitx1, a transcription factor gene with HLrestricted expression, is the most upstream regulator of HL patterning in mice,
exerting some, but not all of its patterning activity by regulating expression of
another HL-restricted transcription factor gene, Tbx4. To determine the
specific roles of these genes, we have performed expression profiling of Pitx1
knockout HL, as well as ChIP-seq experiments for Pitx1 and Tbx4 in HL tissue.
With these experiments, we are able to identify Pitx1 and Tbx4 targets and
ultimately aim to determine how these targets are deployed over the course of
development in the mouse HL patterning program.
106 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
NorCOMM2 – High-throughput knockout mouse production and phenotyping
Lauryl MJ Nutter1, Marina Gertsenstein3, Ann Flenniken4, S. Lee Adamson4,
Janet Rossant2, Colin McKerlie1,3.
1
Physiology & Experimental Medicine, 2Developmental & Stem Cell Biology, The
Hospital for Sick Children, Toronto, Canada
3
Toronto Centre for Phenogenomics, Toronto, Canada
4
Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, Canada
The International Mouse Phenotyping Consortium (IMPC) aims to develop an
encyclopedia of mammalian gene function by phenotyping single-gene knockout
mice for every protein-coding gene in the mouse genome. All of these mouse
lines will
•
Be on the C57BL/6N background;
•
Have a single gene inactivated by critical exon deletion, introduction
of a nonsense mutation, or insertion of a gene-trap cassette;
•
Be phenotyped across many body systems to identify clinical signs of
disease or developmental disorder; and
•
Be publicly available worldwide.
NorCOMM2 aims to produce 380 and phenotype 280 mutant mouse lines
generated from the International Knockout Mouse Consortium embryonic stem
cell resource or by CRISPR/Cas9-mediated mutagenesis. This project occurs at
two sites; the Toronto Centre for Phenogenomics (TCP) funded by Genome
Canada and the Mary Lyon Centre at MRC Harwell funded by the UK Medical
Research Council. The knockout genes to be phenotyped at each Centre are
selected from among nominations by Canadian or UK scientists, respectively.
We will describe our methods and results with respect to mouse line
production, our adult and embryo phenotyping pipelines, some of the
phenotypes identified in the first lines through TCP’s pipelines, and the process
for obtaining the mice and data. For more information: www.norcomm2.org.
107 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Study of rga-7 function in hypodermal cells during embryonic elongation in
Caenorhabditis elegans
Marie-Hélène Ouellette, Emmanuel Martin, Germain Lacoste-Caron, Karim
Hamiche and Sarah Jenna
Department of Chemistry, Pharmaqam, Biomed, Université du Québec à
Montréal (UQÀM), Montréal, Québec, H3C 3P8, Canada
Early and late embryonic elongation in C. elegans involves important
morphological changes in hypodermal cells. Early elongation is controlled by
contractions of circumferential actin filament bundles (CFBs) and is regulated
by two pathways: mel-11/let-502 and pix-1/pak-1, controlling the
phosphorylation of myosin light chains. pix-1 and pak-1 also control late
elongation through mediation of mecanotransduction pathways from muscles to
hypodermis.
We have identified a new RhoGAP coding gene, rga-7, who plays a role in both
early and late elongation. rga-7 appears to code for three transcripts, rga-7l, m and –s, all expressed in embryos hypodermis. These transcripts code for
proteins with F-Bar, C1 and RhoGAP domains. We showed that RGA-7 has a GAP
activity towards CDC-42 and RHO-1 in vitro. Epistatic studies also suggest that
rga-7 acts in parallel of let-502 and pix-1/pak-1 pathways during both early and
late elongation and that it functions upstream or in parallel of wsp-1, a cdc-42effector shown to control actin polymerisation. In addition, RGA-7::GFP
appears to be located at the apical membrane of hypodermal cells where it
intercalates between CFBs. We are currently investigating the molecular
function of RGA-7 in these cells and its potential regulatory role on the actin
cytoskeleton organisation during elongation.
108 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Mitosis-associated cell dispersal drives epithelial cell rearrangements within
the branching ureteric bud
Adam Packard and Frank Costantini
Department of Genetics and Development, Columbia University, New York, NY
10032, USA
The ureteric bud (UB) is an epithelial tube that undergoes branching
morphogenesis, giving rise to the renal collecting ducts. Although the genes
that regulate UB development and branching are well studied, the cellular
behaviors involved remain obscure. Using time-lapse microscopy combined
with fluorescent-labeling techniques, we study morphogenesis at the single-cell
level, within the tips of the branching UB. We find that, contrary to mitotic
cells in many epithelia, whose daughter cells remain in contact, epithelial cells
of the UB tip disperse immediately following mitosis. In a process we term
“mitosis-associated cell dispersal” (Developmental Cell. 2013; 27(3): 319-30),
we observe that pre-mitotic cells round up and move apically; mitosis occurs
within the lumen – while a thin process maintains connection to the basal
surface. One daughter cell inherits the basal process, allowing reinsertion at
the site of origin, while the other daughter reinserts one-to-three celldiameters away. Apical contact is maintained between daughter cells until the
untethered cell reestablishes basal surface contact, likely limiting the initial
distance of dispersal. Since mitosis occurs at a high rate in the UB tips, this
behavior causes extensive cell rearrangements that may contribute to
branching morphogenesis; and we are currently exploring other developing
epithelia for similar behavior.
109 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Molecular mechanisms of Pax7 for differentiation of POMC cells
Audrey Pelletier, Jacques Drouin
IRCM, 110, avenue des Pins Ouest, Montréal (Québec) Canada H2W 1R7
Among the six endocrine cell types of the pituitary, only the anterior lobe
corticotropes and the intermediate lobe melanotropes express the POMC gene.
Studies in our lab revealed that the transcription factor Pax7 is a selector of
the intermediate lobe. Pax7 appears to achieve this by acting as a pioneer
factor that binds a specific DNA sequence in compacted chromatin, leading to
its opening and binding of other transcription factors. Pax7 has two DNA
binding domains, paired and HD, and binds motifs that correspond to either
domain. In addition, a composite target sequence composed of both motifs
juxtaposed next to each other was associated with the pioneer action of Pax7.
Here, we investigated the molecular basis underlying the different DNA binding
modalities, including affinity for the various DNA sequences and interactions
with other proteins. We assessed this by EMSA, and found that Pax7 has a
greater affinity for the composite motif. These results suggest that a stronger
interaction of Pax7 with the composite sequence allows the pioneer action that
is essential for cell fate determination. However, further investigations, both
structural and in vivo, are required to understand the unique features of
chromatin pioneering compared to classical transcriptional activation.
110 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
TashT is a novel mouse model that phenocopies both the variable
penetrance and male sex-bias of Hirschsprung’s disease
Bergeron KF, Cardinal T, Touré AM and Pilon N.
Department of biological sciences and BioMed research center, University of
Quebec at Montreal (UQAM)
Neural crest cells (NCC) are a transient migratory cell population that
generates diverse cell types such as peripheral neurons and glia as well as
melanocytes. Via an insertional mutation screen for loci affecting NCC
development, we identified several mouse lines that combine defects in
pigmentation and formation of the enteric nervous system. One of these lines,
named TashT, displays an aganglionic megacolon phenotype in a subset of
homozygous animals and, most interestingly, almost exclusively in males. This
phenotype is highly reminiscent of human Hirschsprung’s disease, a
neurocristopathy with an incidence of 1 in 5000 newborns and a currently
unexplained 4:1 male sex bias.
We localized the TashT transgene insertion site in a gene desert containing
multiple highly conserved elements on chromosome 10. Migration assays as well
as time-lapse imaging showed that the TashT megacolon phenotype is due to
defective migration of NCC within the gut mesenchyme, a defect generally
more severe in males than females. At the molecular level, RNAseq analysis of
TashT enteric NCC notably revealed upregulation of many genes encoding
secreted proteins and downregulation of several X-linked genes. This analysis
also identified the novel gene Fam162b as a strong candidate for being the
TashT causative gene. Fam162b is located near the transgene insertion site and
reporter gene as well as 3C assays suggest that this TashT overexpressed gene
is normally repressed in NCC via long range interactions with some of the highly
conserved elements near the transgene insertion site.
Altogether, our results demonstrate that the TashT line represents a unique
mouse model that will help understand the male sex bias of Hirschsprung’s
disease.
111 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
CTCF is critical for hindlimb development
Katherine Rabicki1,3, Jason Bush1,3, Nathalie Bérubé2,3, Frank Beier1,3
1
Department of Physiology & Pharmacology, 2Department of Pediatrics and
Department of Biochemistry, Schulich School of Medicine & Dentistry, Western
University, London, Ontario, Canada
3
Children's Health Research Institute, London, Ontario, Canada
Mutations in the gene encoding the chromatin organizer CCCTC-binding factor
(CTCF) have recently been identified in patients with intellectual disability and
skeletal defects. Studies have additionally demonstrated that deletion of CTCF
in murine limb mesenchyme causes massive apoptosis in the forelimb, and
stunted growth coupled with oligodactyly in the hindlimb. We aim to
investigate the specific role of CTCF in hindlimb development. We used the
Cre-LoxP system to conditionally inactivate CTCF in developing limb
mesenchyme using the Prx1 promoter. Mutant and control mice are collected
at various stages of development, and histology is performed to analyze cell
proliferation and death. In situ hybridization and qPCR for candidate target
genes will be conducted, and chromatin immunoprecipitation will be done to
examine whether CTCF binds to these targets. Our results confirm that
hindlimbs of mutant animals are severely shortened and show oligodactyly,
suggesting that CTCF is crucial for regulating hindlimb development.
112 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
C. elegans as a model to study stem cell niche behavior during development
Alexia Rabilotta1, Paul S. Maddox2, Jean-Claude Labbé1
1
Institut de recherché en immunologie et en cancérologie (IRIC), Université de
Montréal, QC, Canada
2
Department of Biology, University of North Carolina, Chapel Hill, NC, USA
We are using C. elegans as a model to understand how stem cells functionally
interact with their niche during development. In C. elegans, a single somatic
distal tip cell (DTC) located at the distal part of the gonad acts as a germline
stem cell (GSC) niche. Maintenance of the most distal GSCs in an
undifferentiated state is mediated by Notch signaling trough expression of the
Delta-like ligand LAG-2 by the DTC. Interestingly, the shape of the DTC changes
during development, displaying membrane extensions termed cytonemes in
adult animals. Because cytonemes allow the DTC to increase its number of
contacts with GSCs, they might influence stem cell proliferation and selfrenewal during development.
Using live imaging approaches, we are currently monitoring how GSCs divide
relatively to cytonemes. In preliminary experiments, we unexpectedly found
that perturbing GSC division or cell fate drastically decreased cytoneme
formation, suggesting that GSCs themselves influence the niche morphology.
We are currently characterizing how signaling from GSCs promotes DTC
maturation. This work highlights the existence of bi-directionality in the
communication between stem cells and their niche in vivo.
113 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Transcriptomics approach to understanding the role of Wnt signaling in C.
elegans development
Ayush Ranawade and Bhagwati Gupta
Department of Biology, McMaster University, 1280 Main St W, Hamilton, ON L8S
4K1
Wnt signaling is a conserved intercellular signaling pathway involved in diverse
developmental processes in both vertebrates and invertebrates. In the
nematode C. elegans, PRY-1/AXIN mediated canonical Wnt signaling pathway is
involved in the proliferation and specification of neuronal and epidermal cells.
PRY-1/AXIN negatively regulates Wnt signaling as the loss of pry-1 results in
constitutive activation of Wnt pathway targets. We have identified pry-1mediated Wnt targets using an RNAseq approach. The computational analysis
has revealed a total of 770 candidates in pry-1 mutant background with an
average fold change of 1.5 (112 up and 652 down compared to wild-type
levels). The classification of putative Wnt targets was based on GO terms as
well as other sources including Wormbase. This analysis revealed several
functional classes such as neuronal development, axonal guidance, and
reproductive system development. Genes belonging to the conserved families
such as lipid transportation, hedgehog and transcription factors were also
identified. Current efforts are focused on characterizing a subset of candidate
genes and their cellular and molecular roles in C. elegans. Analysis of Wnt
responsive genes will further expand our knowledge of the genetic controls in
developmental processes.
114 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Extension of Filopodia and Lamellopodia requires Robo/Slit and
Frazzled/Netrin signalling during Drosophila heart morphogenesis
Qamber Raza and Roger Jacobs
LSB 420, Department of Biology, McMaster University, 1280 Main St. W.,
Hamilton, ON, L8S 4L8
Similar to vertebrates, the Drosophila heart arises from mesodermal precursors
which form two bilateral rows of cardioblasts that migrate dorsally towards the
midline and fuse with their contralateral partners to form the dorsal vessel.
During migration, the leading edge of the CBs extends finger-like processes
which we postulate play a role in sensing guidance cues during migration.
Time-lapse fluorescent imaging allowed us to characterise their dynamic
nature. Cardioblasts increase the number of extensions as they approach the
midline, suggesting that they are responding to a signal present at the midline.
Our live-imaging movies suggest that signalling also occurs between ipsilateral
cells.
Robo/Slit and Frazzled/Netrin signalling are required for heart lumen formation
in Drosophila. We speculated that the secreted ligands Slit and Netrin, might
signal through their respective receptors Robo and Frazzled, on the
cardioblasts to increase filopodial extension as they approach the midline. As
expected, in Robo, Slit and Frazzled mutants, cardioblasts exhibit reduced
filopodial activity. Interestingly in the absence of Robo/Slit, but not Frazzled,
we also measured a decrease in migration speed and disruption of adhesion
between ipsilateral cardioblasts. In conclusion, we demonstrate that guidance
molecules modify cell motility events before lumen formation, but are not
required for medial migration.
115 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Effect of FZD4 on Development of Severe Retinopathy of Prematurity Using
the Ocular Ischemic Mouse Model
Johane Robitaille,1,2 Joanna Borowska,1 Michael Ngo,3 Sara Nejat,4 Yanli Zhou,3
Godfrey Heathecote,2 Melanie Kelly,1,3 , and Christopher McMaster 3
Departments of Ophthalmology and Visual Sciences1, Pathology2, and
Pharmacology3, Dalhousie University, Halifax, Nova Scotia; Department of
Pathology and Molecular Medicine, McMaster University, Hamilton, Ontario4
Familial exudative vitreoretinopathy (FEVR) is a hereditary developmental
retinal vascular disorder that shares phenotypic and molecular overlap with the
more common, non-hereditary retinopathy of prematurity (ROP). The purpose
of the study was to test the hypothesis that hereditary factors that cause FEVR
predispose to developing severe ROP.
We exposed litters of mice producing wild type and fzd4+/- pups to increasing
levels of O2 between P7 and P12 using the ocular ischemic retinopathy (OIR)
model. Mice were examined at P12 and P17 for area of avascular retina and
pattern of vessel formation using descriptive measures and digital imaging
software.
Exposing the mice to 65% O2 for three days, followed by 21% for 24 hours and
then 65% for the final day induced more pathological changes in fzd4+/heterozygous mice compared to wild type littermates. Irregular vascular
patterns were more prominent in heterozygous mice.
Phenotypic changes have not been reported in fzd4+/- mice. We demonstrate
that using a modified version of the OIR model, mice with haploinsufficiency of
FZD4 are at risk of developing more severe disease than wild type mice. This
reinforces the finding from humans that mild mutations in the FZD4 gene are
associated with severe ROP.
116 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
AMPK buffers adverse epigenetic change and consequent transgenerational
reproductive defects following acute nutrient/energy stress
Emilie Demoinet1, Shaolin Li1 and Richard Roy1
1
Department of Biology, McGill University, Montreal, QC, Canada.
Chromatin modifications are often associated with changes in gene expression
that can persist throughout the lifetime of the organism or even span multiple
generations. We have found that the master metabolic regulator AMP-activated
protein kinase (AMPK) is critical for metabolic adjustment and subsequent
survival during periods of acute nutrient/energy stress in C. elegans larvae. In
addition, AMPK is also required to buffer modifications to the chromatin
landscape to ensure that gene expression remains inactive in the primordial
germ cells (PGC) during adverse physiological conditions. In its absence
H3K4me3 levels increase, compromising the reproductive fitness of, not only
the generation that experienced the stress, but also the subsequent unstressed
generations. AMPK phosphorylates the COMPASS complex histone
methyltransferase SET-2, while monoubiquitylated H2B levels, a key indicator
of transcriptional progression, increase in its absence. Our data suggest that
AMPK impinges on at least two critical targets to ensure that transcriptional
pausing is maintained until an energy/nutrient-dependent contingency is
satisfied, thereby coordinating the initiation of germ line development with
physiological constraints.
117 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
CPE-sensitive claudins are essential for neural tube closure
Aimee K. Ryan*1,2,3, Amanda Baumholtz2, and Annie Simard3
Departments of 1Pediatrics, 2Human Genetics and 3Experimental Medicine,
McGill University, Montréal, Quebec, Research Institute of the McGill University
Health Centre, Room 415-2 Place Toulon, 4060 St. Catherine St. West,
Montréal, Quebec, H3Z 2Z3
Neurulation converts the flat neural plate into a closed neural tube. In North
America, the incidence of neural tube defects is 1 in 1000 live births. Members
of the claudin family of tight junction proteins are differentially expressed in
neural and non-neural ectoderm. We used the C-terminal domain of
Clostridium perfringens enterotoxin (cCPE) to remove a subset of claudins from
the ectoderm of chick embryos during neurulation. 100% of cCPE-treated
embryos had open neural tube defects that could not be rescued by folic acid
treatment. No defects were observed in control embryos. cCPE-treated
embryos had shortened anterior-posterior axis and abnormally fused somites,
indicative of a convergent extension defect. Time course experiments revealed
that cCPE-sensitive claudins were required during elevation of the neural folds
and for formation of the median hinge point. Analysis of the embryos revealed
that there was a failure of apical constriction of cells at the midline and that
the apical surface of these cells was abnormal. However, the neural ectoderm
was appropriately patterned along its anterior-posterior and dorsal-ventral axes
and cells had normal apical-basal polarity. Thus, claudins function to generate
the cell shape changes that drive neural tube morphogenesis and are not
required for the initial differentiation of the neural ectoderm.
118 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Characterisation of ski-like and c-Myc in the TGF-β pathway during axolotl
limb regeneration
Fadi Sader1 and Stéphane Roy
1,2
1
Dept. of Biochemistry & 2 Dept. of Stomatology, Université de Montréal,
Montréal, Quebec, H3T 1J4
The axolotl (Ambystoma mexicanum) is a vertebrate with remarkable
regeneration capacities. It can perfectly regenerate parts of it body following
different kinds of amputations. Our lab is interested in understanding the
biological processes enabling axolotl regeneration. Limb regeneration is studied
for its ease and low incidence of adverse effects on the animal’s health.
Axolotl regeneration can be described as a bi-phasic process in which the first
phase has some similarities with mammalian wound healing and second phase
similarities with development. Published results from our lab showed that TGFβ1 is essential for limb regeneration. A treatment with a specific inhibitor (SB431542) prevents regeneration. Following these results we wanted to assess
functional analysis and characterise TGF-β target genes during regeneration.
We have established expression patterns for TGF-β targets c-Myc and ski-like
(SnoN). Results show that both oncogenes are up-regulated during the first
phase. SnoN is a transcriptional co-repressor for the TGF-β pathway with
potential functions in preventing cellular differentiation and c-Myc a
transcriptional regulator for proliferation and cell cycle progression. These
proteins might be essential for proliferation and blockage of cellular
differentiation (to allow cellular dedifferentiation). Preliminary results show
that c-Myc expression correlates with TGF-β signalling and is down-regulated
following SB-431542 treatment.
119 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Evolution and genetics of the patella
Mark E. Samuels
Université de Montréal, Centre de recherche du CHU Ste-Justine, Montréal, QC
The patella is a sesamoid bone located in the tendons of the hindlimb knee
joint. Although aspects of knee architecture are ancient and conserved among
most Tetrapods, the evolutionary occurrence of an ossified patella is highly
variable. Among modern groups it is found in many birds, lizards, and all
placental mammals retaining a hindlimb. However it is absent in most
marsupials, but present in the egg-laying monotremes which are thought to
have diverged prior to the placental/marsupial divergence. The patella is
absent in dinosaurs and other modern reptilian groups, and in early extinct
mammals, but is present in other extinct mammalian groups particularly
multituberculates. These observations are best interpreted that the patella
arose independently multiple times across evolution, and may also have been
lost in some groups. There are several human genetic conditions in which the
patella is either absent or severely reduced. Some of the identified causal
genes play roles in pattern formation, such as forelimb/hindlimb or
dorsal/ventral determination, whereas others have functions in chromosome
structure or replication; the specific role of the latter genes in patellar
development remains to be determined. Clearly the patella plays an important
role in hindlimb function and is under close genetic control.
120 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Induction and dorsal restriction of Paired-box 3 (Pax3) gene expression in
the caudal neuroectoderm is mediated by integration of multiple pathways
on a short neural crest enhancer
Oraly Sanchez-Ferras, Guillaume Bernas, Emilie Laberge-Perrault and Nicolas
Pilon.
Molecular Genetics of Development Laboratory, Department of Biological
Sciences and BioMed Research Center, Faculty of Sciences, Université du
Québec à Montréal (UQAM)
Building an embryo from an initial population of equivalent cells requires
precise spatiotemporal control of gene expression. In the caudal neurectoderm,
expression of the essential neural crest and neural tube developmental gene
Pax3 is controlled by two redundant sets of cisregulatory modules (CRMs), that
integrate anterior-posterior as well as dorsal-ventral instructive cues. In
previous work, we characterized the posteriorizing Wnt-mediated regulation of
Pax3 expression and identified the Cdx transcription factors (Cdx1/2/4) as
critical intermediates in this process. We identified the neural crest enhancer-2
(NCE2) from the 5’-flanking region of Pax3 as a Cdx-dependent CRM that
recapitulates the restricted expression of Pax3 in the mouse caudal
neuroectoderm. While this is consistent with a key role in relaying the
inductive signal from posteriorizing Wnt ligands, the broad expression of Cdx
proteins in the tailbud region suggests that other inputs must act to restrict the
activity of NCE2. Here, we report a novel role for the transcription factor Zic2
in this regulation. Our data strongly suggests that Zic2 is involved in the
induction (as a direct Pax3NCE2 activator and Cdx neural cofactor) as well as
the maintenance of Pax3 dorsal restriction (as a target of the ventral Shh
repressive input). We also provide evidence that the inductive Cdx-Zic2
interaction is integrated on NCE2 with a positive input from the neural-specific
transcription factor Sox2 and the dorsal BMP-Smad signaling pathway.
Altogether, our data provide important mechanistic insights into the
coordinated integration of different signaling pathways on a short Pax3 CRM.
121 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Ectopic lipid accumulation in tissue aging and lifespan determination
Sebastian Schmeisser and Richard Roy
Department of Biology, 1205 avenue Docteur Penfield, McGill University,
Montreal, QC. Canada H3A 1B1
Recent studies have revealed that fat metabolism and lifespan are linked,
although the underlying mechanisms are poorly understood. In humans, the
accumulation of fat deposits in non-adipose tissue (so-called ectopic fat) can
be found in obese and aged individuals and has been linked to the onset of agerelated diseases. More provocatively, these ectopic fat deposits themselves
could be involved in the aging process itself and thus play a role in the
determination of lifespan.
To address the impact of ectopic fat deposits on lifespan we turned to the
well-characterized model organism Caenorhabditis elegans.
In order to quantify ectopic fat deposits in vivo, we have taken advantage of
non-linear microscopy that allows us to accurately quantify ectopic fat in
muscle cells. Using various genetic backgrounds, we will monitor the size and
occurrence of intramyocellular lipid droplets during different developmental
and metabolic conditions known to affect lifespan and/or ectopic fat formation
such as high-glucose (obesity model), reduced insulin signaling, dietary
restriction and altered mitochondrial function.
The results may provide novel insights in our capacity to prevent and
ameliorate clinical features commonly associated with obesity, type 2 diabetes
and metabolic syndrome to establish new therapeutic strategies and ultimately
promote healthy lifespan in humans.
122 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
The role of Gata3 in prostate epithelial morphogenesis during development
Maxwell Shafer, Alana Nguyen, Mathieu Tremblay, Maxime Bouchard
Goodman Cancer Research Centre, and Department of Biochemistry, McGill
University,
Montréal, Quebec, CA
The prostate develops in the mass of tissue known as the UGS. Epithelial cells
branch from the UGS forming ducts composed of differentiated basal, and
luminal cell types. Gata3 is a transcription factor that is expressed specifically
in the prostate epithelium and it’s loss in early prostate development leads to
severe defects. Immunostaining for markers of the basal and luminal cell
lineages suggest an increase in the double positive, progenitor cell population
in Gata3-/- mice. Analysis of polarity markers (such as E-cadherin, ZO-1 and
Par3) showed a disruption in tissue polarity and loss of apical localization of the
spindle regulator aPKCζ. Further analysis indicates a defect in the orientation
of the angle of cell division in Gata3-/- prostates. We have also observed a
decrease in the expression of non-canonical Notch pathway members such as
Strawberry Notch (Sbno1) and the Musashi proteins (Msi1/2). On the basis of
these results, we hypothesize that Gata3 regulates key effectors of
stem/progenitor cell homeostasis, division and differentiation. This research
may lead to the discovery of therapeutic targets for the treatment and/or
prevention of prostate cancer and contribute to our understanding of the
embryonic development of an important regulatory organ.
123 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Molecular mechanisms of renal lineage specification
Sharma, R.1, Bouchard, M.
1
Rosalind and Morris Goodman Cancer Centre, McGill University, 1160 Pine
Avenue West, Montreal, Quebec, Canada, H3A1A3
Embryonic development requires the successive induction of new cell lineages.
Previous studies from our lab have shown that Pax2/8 genes are necessary and
sufficient for lineage commitment and differentiation of the embryonic
mesonephros (primitive kidney). However the exact process by which Pax2 and
the renal fate is induced from intermediate mesoderm progenitors still remains
elusive. Studies have shown that that signals from surrounding tissues (paraxial
mesoderm, lateral plate mesoderm and surface ectoderm) are important for
renal cell lineage induction. Additional evidence suggests that some of these
signals activate Pax2 expression in the intermediate mesoderm, thus activating
renal specification. Hence, we hypothesize that extracellular signals
emanating from surrounding tissues activate Pax2 expression and renal lineage
specification from developing progenitor cells. To examine this hypothesis, we
have developed a primary culture system in which purified mesonephric cells
expressing a Pax2-GFP transgene gradually turn off GFP expression in culture,
acquiring a progenitor-like state. We are using this system to dissect the
mechanisms of renal lineage specification from these progenitors by
reactivation of GFP by candidate Pax2 inducing factors. Our long-term goal is
to obtain a complete genetic analysis of renal lineage regulators and to assess
their function using cell culture studies and gene knockout analyses in mice.
124 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Hoxome13: a systemic approach to understand Hox biology
Rushikesh Sheth, Stephen Nemec, Jacques Drouin and Marie Kmita
Institut de recherches cliniques de Montréal (IRCM), 110 avenue des Pins Ouest
Montréal, QC, H2W 1R7
Since the initial discovery of the Hox gene family, extensive genetic analyses
have revealed their key role in developmental processes. Although it is known
that Hox genes encode transcription factor, their targets, how they regulate
transcriptional outputs in given tissue and what are their co-factors remains
largely elusive. This is in part due to the functional redundancy existing
between subsets of Hox genes. During the limb development, only two Hox
genes are essential for the morphogenesis of the hands and feet, namely
HoxA13 and HoxD13. Therefore, distal limb bud tissue (the presumptive
hand/foot) is the optimal model system to study the mechanisms by which
these two genes function. We have performed series of genomic studies and
integrating data whole genome transcriptome analysis coupled with epigenetics
data and maps of HoxA13 and HoxD13 in vivo binding on the genome, we are
providing the first comprehensive analysis of HoxA13 and HoxD13 function
during limb development.
125 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Rad23A, a ubiquitin binding protein, regulates E2F1 degradation in
keratinocyte
Randeep K. Singh* and Lina Dagnino*§
*Department of Physiology and Pharmacology, University of Western Ontario,
London, ON N6A 5C1. §Department of Paediatrics, Children's Health Research
Institute, Lawson Health Research Institute, University of Western Ontario,
London, ON N6A 5C1
E2F1 functions as a central hub to determine a cell’s fate to either proliferate
or differentiate. Cellular levels of E2F1 are highly regulated by the ubiquitinproteasome pathway, to enable tight control of E2F1 expression. The
mechanisms of E2F1 degradation in keratinocytes are poorly understood. We
have investigated the effect of Rad23A, a ubiquitin-binding protein, on E2F1
ubiquitination and degradation. Rad23A is localized predominantly to the
cytoplasm. However, exogenous expression of both E2F1 and Rad23A leads to
Rad23A nuclear import in undifferentiated and in differentiated keratinocytes.
Rad23A interacts with E2F1 through its Uba1 and XPC domains. The relative
levels of Rad23A modulate E2F1 abundance. Specifically, we observed reduced
E2F1 degradation in the presence of high Rad23A levels. We also observed
accumulation of polyubiquitinated forms of E2F1 in the presence of
exogenously expressed Rad23A. These observations suggest that Rad23A may
regulate E2F1 levels by binding to the proteasome and hindering E2F1 access to
the degradation machinery. Thus, Rad23A may play a key role in regulating
E2F1 turnover. In contrast, lower Rad23A levels are associated with enhanced
E2F1 degradation. Our studies have identified a novel role for Rad23A in the
regulation of E2F1 activity, by modulating the abundance of this transcription
factor.
126 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Inhibition of GSK3B enhances embryonic stem cell-derived skeletal
myogenesis
Michael Shelton, Jeff Metz, Jun Liu, Richard L. Carpenedo, Simon-Pierre
Demers, William L. Stanford, and Ilona S. Skerjanc
Department of Biochemistry, Microbiology, and Immunology, University of
Ottawa, Ottawa, Ontario, K1H 8M5
Cell therapies for treating muscular dystrophy require an adequate quantity of
muscle progenitor cells (MPC) not yet attainable from adult donors. Here, we
treat human embryonic stem cells (ESCs) with the GSK3-inhibitor CHIR99021,
creating cultures with ~90% skeletal myogenic identity. Gene expression
analysis identified progressive expression of mesoderm, somite,
dermomyotome, and myotome markers, following patterns of embryonic
myogenesis. CHIR99021 markedly enhanced transcript levels of the panmesoderm gene T and paraxial-mesoderm genes MSGN1 and TBX6.
Immunofluorescence confirmed that 90% of cells expressed BrachyuryT
immediately following treatment. After one week, ~60% of cells expressed the
muscle progenitor protein, PAX3. By 7 weeks, 50% of cells were myosin heavy
chain+ve myocytes/myotubes surrounded by a 40% population of PAX7+ve MPCs,
indicating ~90% of cells had achieved myogenic identity. Importantly, the
PAX7+ve MPCs persisted during terminal differentiation, reminiscent of
embryonic satellite cells. These studies establish a foundation for serum-free
and chemically-defined skeletal myogenesis of ESCs.
127 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Comparing lumen size and vascular development between diploid and
triploid zebrafish
Christopher Small, Tillmann Benfey, Bryan Crawford
Triploidy can be induced in many species of fish by preventing the expulsion of
the second polar body using heat or pressure shock shortly after fertilization.
This technique produces a sterile fish with some evidence suggesting more
rapid somatic growth; both traits highly desired by the aquaculture industry.
However, triploid fish are less robust than diploid conspecifics, likely due to a
reduced ability to deliver oxygen to metabolically active tissues. The
mechanism underlying this limitation is largely unexplored. Triploid fish have 3
sets of chromosomes and the correlation between DNA content, nucleus size,
and cell size is maintained so that each cell is larger than its diploid
counterpart. One hypothesis suggests that oxygen delivery is impaired due to
blood flow limitations in the microvascular system, as capillary lumen diameter
is less than the width of an erythrocyte, forcing the cell to undergo
deformation when traversing a capillary – a larger triploid cell may have more
difficulty with this process. This hypothesis is based on the prediction that
lumen diameter, like other morphometric characteristics, is consistent
between diploids and triploids. To test this prediction, I have crossed
Tg(Flk1:GFP) and nacre zebrafish to generate a pigment-less fish with GFP in
the vasculature allowing for in vivo imaging of lumen diameter. This will also
provide an opportunity to explore the effect of cell size and triploidy on
vascular patterning in a developing embryo.
128 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
UBC-25 promotes Ras/MAPK signaling to regulate oocyte growth and
embryonic morphogenesis in C. elegans
Audrey Mideum Song1, Phil Cheng1, Kevin Cullison2, Meera Sundaram2 and
Christian E. Rocheleau1
1
Department of Medicine, McGill University, Montreal, QC
Department of Genetics, University of Pennsylvania School of Medicine,
Philadelphia
2
A highly conserved Ras/Mitogen Activated Protein Kinase (MAPK) signaling
pathway is used repeatedly during C. elegans development to regulate cell
differentiation as well as multiple aspects of germline development including
oocyte growth. We previously identified UBC-25, a putative E2 ubiquitinconjugating enzyme as promoting Ras/MAPK signaling during specification of
the excretory duct cell in both a genome-wide RNAi screen and a traditional
mutagenesis screen. Interestingly, loss of ubc-25 in conjunction with loss of a
Ras/MAPK signaling scaffold, cnk-1, causes an embryonic lethal phenotype and
a large oocyte and embryo phenotypes. An increased oocyte size has been
reported in a conditional allele of mpk-1 Erk and conversely, decreased oocyte
size is associated with loss of the MAPK phosphatase, lip-1, or a gain-offunction mutation in let-60 Ras. Surprisingly, ubc-25 mutants suppress the lip-1
small oocyte phenotype but not that of gck-1(RNAi), another negative regulator
of MPK-1 Erk. Thus UBC-25 is specifically required downstream of LIP-1 MKP.
Consist with a function in the germline, a UBC-25::GFP transgene is expressed
in the germline. We hypothesize that UBC-25 functions closely with MPK-1 Erk
to regulate excretory duct cell specification, embryonic morphogenesis and
oocyte growth.
129 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
A new mechanism for Hirschsprung's disease involving the self-modulation
of neural crest cell microenvironment
Rodolphe Soret, Llilians Gonzalez and Nicolas Pilon
Département des sciences biologiques et Centre de recherche BioMed,
Université du Québec à Montréal, C.P.888 Succ. Centre-Ville, Montréal, H3C
3P8
Gastrointestinal motility is controlled by the enteric nervous system (ENS),
which is derived from neural crest cells (NCC) of vagal origin. These cells
colonize the developing intestines rostrocaudally, and become organized in
ganglia by the concerted action of migration, proliferation, survival and
differentiation processes. Defective colonization results in aganglionosis in the
colon and thus lethal constipation, as seen in Hirschsprung's disease (HSCR). In
order to identify new genes involved in NCC development and ENS formation,
we generated and characterized a new mouse model for HSCR named Holstein.
This mutant line was obtained by random insertion of a Tyrosinase transgene in
an albino background followed by a screen for pigmentation abnormalities.
Homozygous Holstein mice are depigmented and succumb to megacolon around
3 weeks after birth. Analysis of embryonic guts using different markers (Hu
C/D, S100β, Sox10, Ki67 and caspase 3) and time-lapse imaging strongly suggest
that the Holstein megacolon phenotype is caused by a default in enteric NCC
migration. We found that the Holstein transgene integration site is located in a
short deletion of genomic sequences on chromosome 9 between collagen 6
isoform alpha4 (Col6a4) and glycerate kinase (Glyctk) genes. We also found
that the Col6a4 gene is specifically upregulated in Holstein NCC, resulting in
overabundance of collagen in their microenvironment.
Altogether, our data suggest that enteric NCC might regulate their own
microenvironment, highlighting a new mechanism for HSCR.
130 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
The memi gene family is required for female meiosis II in the C. elegans
embryo
J. Tegha-Dunghu, Maryam Ataeian, and Martin Srayko
Department of Biological Sciences, University of Alberta, Edmonton, Alberta
T6G 2E9
Meiosis involves specialized cell divisions that culminate in the production of
haploid gametes. The female meiotic divisions are complicated by the fact that
fertilization often occurs prior to the completion of meiosis II. We use C.
elegans to understand the meiosis-to-mitosis transition. The first meiotic
division in the oocyte is stimulated by a sperm-specific factor termed MSP
(major sperm protein). If oocyte activation occurs without fertilization, the
oocyte still enters meiosis I, but meiosis II is skipped, suggesting that sperm
entry is important for the meiosis II program. We have found that simultaneous
RNAi of three paralogs called memi-1, 2, and 3 (meiosis-to-mitosis) also causes
a skipped meiosis II phenotype. Interestingly, a hypermorphic mutation in
memi-1 results in a distinct phenotype whereby fertilized eggs enter meiosis II
normally, but they do not complete meiosis II. We have also found that MEMI
proteins are enriched in the maternal germline, suggesting that they represent
an oocyte-specific component of a fertilization-dependent pathway that
specifies meiosis II. Using the hypermorphic memi-1 mutation, we have
initiated suppressor screens to identify more genes involved in this pathway.
131 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Modulation of programmed cell death by the inhibitor of apoptosis proteins
is required for appropriate urogenital system morphogenesis
Katie Stewart and Maxime Bouchard
Goodman Cancer Research Centre and Department of Biochemistry, McGill
University, Montreal
The appropriate connection of the ureter to the bladder (ureter maturation)
requires the removal of the intervening common nephric duct (CND), a process
driven by apoptosis. Previously, we have shown that loss of LAR-family tyrosine
phosphatases results in deficient ureter maturation due to reduced apoptosis.
Using mouse embryonic fibroblasts derived from LAR-family triple knockout
animals we have confirmed this defect in response to intrinsic and extrinsic
apoptotic stimuli, as they are able to activate caspases 8 and 9 while failing to
activate caspases 3/7. This is associated with dysregulated activity of the
cellular inhibitor of apoptosis protein (cIAP) family, as apoptosis is rescued by
co-administration of the cIAP1/2 antagonist BV6. Importantly, the regulation of
the IAP pathway is crucial during ureter development as both treatment of
E11.5 urogenital systems with BV6 in culture, and genetic inactivation of cIAP1
in vivo, results in an acceleration of apoptotic CND elimination associated with
elevated levels of caspases 3/7. Developmentally this is predicted to result in
the retrograde flow of urine from the bladder to the kidney, known as
vesicoureteral reflux. Accordingly, ink injection assays on postnatal cIAP1-/pups revealed VUR in knockout animals, highlighting the importance of
regulated IAP activity during ureter maturation.
132 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
The role of Shroom3 in kidney development.
Alexandra Sull, Rami Halabi, Hadiseh Khaili, Darren Bridgewater, and Thomas
Drysdale
Department of Physiology and Pharmacology, Developmental Biology Program,
Children’s Health Research Institute, Lawson Health Research Institute,
Department of Pediatrics, McMaster University, Department of Pathology and
Molecular Medicine
Chronic kidney disease affects approximately 10% of the population in
industrialized nations causing high morbidity and mortality. Recent GWAS
studies have associated the SHROOM3 locus with kidney functioning. Shroom3 is
an actin-binding protein essential for apical constriction and apical-basal cell
elongation. Given that the SHROOM3 locus correlates with kidney functioning,
homozygous and heterozygous loss may result in impaired kidney functioning.
Utilizing C57BL/6 mice with a gene trap that renders Shroom3 inactive, the
role of Shroom3 can be elucidated during different embryonic time points and
in adult wild-type and heterozygous mice. We found Shroom3 is expressed
within the kidney and expression appears to be evolutionarily conserved in
lower vertebrates. Shroom3 is specifically expressed in the glomeruli, and at
later time points, the collecting ducts. Glomerular counts show that
homozygous loss of Shroom3 results in decreased glomerular number compared
to wild-type. This may be in part due to glomerular death and glomerular cysts
found in E13.5 heterozygous and mutant (-/-) embryos. Further, a case of
severe hydronephrosis seen in an adult male heterozygous mouse suggests
detrimental effects of even heterozygous expression of Shroom3. Therefore,
loss of Shroom3 decreases glomerular number, which may result in impaired
kidney functioning and serious kidney disease.
133 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Analyzing cardiac function in Xenopus embryos using a novel imaging system
Judith Sull1, Kambiz Norozi2, and Thomas Drysdale3
Department of Physiology and Pharmacology1,3, Developmental Biology
Program1,3, Children’s Health Research Institute1,3, Lawson Health Research
Institute1,3, Lawson Health Sciences Centre2, Department of Paediatrics1,2,3,
University of Western Ontario1,3
Congenital heart defects (CHDs) account for the most prevalent group of
abnormalities seen at birth and have been associated with considerable
morbidity and mortality. Cardiogenesis is a delicately orchestrated process that
is easily disrupted leading to CHDs. Embryonic cardiac development is well
characterized in Xenopus and despite anatomical differences, cardiac
development among vertebrates appears to be conserved. There is limited
knowledge on the link between changes in cardiac morphology and changes in
cardiac function. Therefore, our lab proposes using a novel imaging system to
analyze cardiac function in Xenopus laevis embryos to elucidate on the possible
association. A normative sample of embryos has been analyzed to measure
cardiac function. Utilization of treatments that have been known to alter
cardiac development were applied. Various cardiac function parameters have
been analyzed to observe possible differences in cardiac function after
treatment. Furthermore, in situ hybridizations have been performed to identify
possible changes in cardiac morphology of treatment groups. Preliminary
results have shown significant differences in some heart function parameters
and possible changes in cardiac morphology after various treatments at several
stages. Overall, this novel imaging system seems to serve as a promising tool in
the accurate measurement of cardiac function in Xenopus embryos.
134 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Liver X Receptor activation delays chondrocyte hypertrophy during
endochondral bone growth
Margaret Man-Ger Sun and Frank Beier
Department of Physiology & Pharmacology, Schulich School of Medicine &
Dentistry, The University of Western Ontario, London, ON
Activation of the Liver X Receptor (LXR) has recently been identified as a
therapeutic strategy for osteoarthritis (OA). LXRβ-null mice display OA-like
symptoms and LXR agonist administration to OA articular cartilage explants
suppresses proteoglycan degradation. We investigated the effect of LXR
activation on chondrocyte differentiation to elucidate the molecular
mechanisms behind its protective effects against OA.
The specific LXR agonist, GW3965, was used to examine the effect of LXR
activation on chondrocyte differentiation in three different chondrocyte model
systems.
Chondrocyte hypertrophy was suppressed by GW3965 treatment, as shown by
decreased hypertrophic zone length in tibia organ culture, decreased alkaline
phosphatase staining, and down-regulation of hypertrophic gene expression in
micromass culture and differentiating ATDC5 cells. Increased chondrocyte
proliferation and up-regulation of Col2a1 expression suggest hypertrophy is
suppressed secondary to prolonged proliferation.
Our findings regarding LXR’s role in cartilage development suggest that LXR
activation prevents ectopic chondrocyte hypertrophy and resulting cartilage
breakdown, further solidifying LXR’s potential as a therapeutic target in OA.
135 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
A role for the transcription factor Lmx1b in pain modality discrimination
Nora Szabo1, Ronan V. Da Silva1, Susana G. Sotocinal2, Jeffrey S. Mogil2, Artur
Kania1,3,4
1
Neural Circuit Development Lab, Institut de recherches cliniques de Montréal
(IRCM), 110 Avenue des Pins Ouest, Montréal QC
2
Department of Psychology, McGill University, Montreal, QC
3
Division of Experimental Medicine, McGill University, Montréal, QC
4
Faculté de Medecine, Université de Montréal, Montréal, QC
One important aspect of nociception is the ability to discriminate between
modalities such as noxious heat versus mechanical stimulation.
Electrophysiological studies suggest that neuronal circuits devoted to specific
pain modalities are organised into “labeled lines”, such that pain sensation is
processed by neurons primarily devoted to the sensation of a particular pain
modality. While molecular correlates of such sorting in vertebrates are evident
at the level of primary sensory neurons, few molecular markers of modality
discrimination have been found in the dorsal horn of the spinal cord.
Using a candidate gene approach we focussed on the transcription factor
Lmx1b, which is expressed in dorsal horn neurons and essential for their normal
development, but its role in nociception has not been characterised in
postnatal animals. To assess the behavioral consequences of deleting Lmx1b in
the spinal cord, we generated a conditional Lmx1b knockout mouse line using a
spinal cord-specific Cre recombinase driver. Such mice show robustly lowered
sensitivity to mechanical noxious stimulation but have normal thermal
nociception. We are currently exploring the possibility that Lmx1b defines a
population of dorsal horn neurons devoted to mechanical pain sensation, in line
with the observation that human LMX1B mutations result in modality-specific
nociception defects.
136 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Pten phosphatase regulates amacrine cell differentiation in the developing
retina
Nobuhiko Tachibana, Robert Cantrup, Yacine Touahri, Dawn Zinyk, Gaurav
Kaushik, Rajiv Dixit, Carol Schuurmans
Hotchkiss Brain Institute, Alberta Children’s Hospital Research Institute,
University of Calgary, Calgary, Alberta, T2N 4N1
As one of the five main senses, vision is the most critical as it allows us to
navigate in our surrounding environment. Within the eye, the retina is the most
essential structure, as it contains the neurons that convert light into electrical
information that is processed into visual perception in the brain. The retina
contains one glial and six neuronal cell types that are derived from a common
pool of multipotent progenitors. How appropriate numbers of each retinal cell
type are generated remains poorly understood. I investigate how the Pten
tumour suppressor gene controls the differentiation of one type of retinal
interneuron – amacrine cells. By performing birthdating studies in retinalspecific Pten conditional knock-outs (cKO), I found that fewer amacrine cells
are generated at all stages of embryonic development. Amacrine cell
differentiation is controlled by TgfβII negative feedback signaling. I have
preliminary evidence that loss of Pten enhances feedback signaling in the
retina, with higher levels of pSmad2/3, downstream TgfβII effectors, in Pten
cKO retinas. Taken together, my studies will further our understanding of how
molecular signals control the timing of cellular differentiation in the retina,
ensuring that appropriate numbers of the correct types of retinal cells are
generated.
137 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
The TashT locus genetically interacts with other Hirschsprung’s diseaseassociated loci in a male-biased manner
Aboubacrine M. Touré1, David W. Silversides2 and Nicolas Pilon1
1
Laboratoire de génétique moléculaire du développement, Département des
sciences biologiques et Centre BioMed, Université du Québec à Montréal
2
Département de biomédecine vétérinaire, Université de Montréal
Hirschsprung’s disease (HSCR; also known as aganglionic megacolon) is a
congenital condition in which the enteric nervous system (ENS), formed from
neural crest cells (NCC), is absent from the terminal bowel. Within the general
population, 1 in 5000 newborns are affected with a 4:1 male sex bias. The
genetics of HSCR is complex and both the phenotypic variability and
incomplete penetrance is believed to be explained by genetic interactions
between HSCR-associated genes. The male sex bias is currently unexplained.
TashT, Holstein and Spot are novel mouse models for HSCR, which have been
generated via an insertional mutation screen aimed at identifying new genes
important for NCC. For all three lines, heterozygotes display no obvious ENS
defect whereas homozygotes die from megacolon as a result of defective NCC
migration toward the hindgut. While this phenotype is fully penetrant without
sex bias in Holstein and Spot lines, it occurs in a subset of TashT pups with a
striking 17:1 male bias. We hypothesized that the TashT locus might interact
with other HSCR-associated loci and thereby influence the sex ratio of the
megacolon phenotype. Accordingly, we found that the TashT locus not only
genetically interacts with both Holstein and Spot loci but also in a male-biased
manner: 3/7 males vs 0/9 females for TashTtg/+:: Spottg/+; and 4/6 males vs 2/5
females for TashTtg/tg::Holsteintg/+). Our data further demonstrate that the
TashT line represents a great tool that will help understand the intriguing male
sex-bias of HSCR.
138 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
GATA3 antagonizes prostate cancer progession
Mathieu Tremblaya, Alana H.T. Nguyena, Maxwell Shafera, Katharina Haighb,
Ismaël Hervé Koumakpayic, Marilène Paquetd, Pier Paolo Pandolfie, Anne-Marie
Mes-Massonf, Fred Saadc,f, Jody J. Haighb, Maxime Boucharda
a
Goodman Cancer Research Centre and Department of Biochemistry, McGill
University,
b
Department of Biomedical Molecular Biology, Ghent University, Belgium
c
Department of Surgery/Urology, Université de Montréal
d
Comparative Medicine and Animal Resources Centre, McGill University
e
Harvard Medical School, Harvard University, USA
f
Institut du Cancer de Montréal, Université de Montréal
Loss of the tumor suppressor PTEN is a common occurrence in prostate cancer.
This aberration leads to the ectopic activation of the PI3K-Akt pathway, which
promotes tumor growth. Here, we show that the transcription factor Gata3 is
progressively lost in Pten-deficient mouse prostate tumors. Using both
conditional loss- and gain-of-function approaches, we show that Gata3
inactivation in Pten-deficient prostates accelerates tumor invasion, whereas
enforced expression of GATA3 in Pten-deficient tissues markedly delays tumor
progression. Moreover, the dramatic increase in sphere-forming potential of
Pten-deficient stem cells was reduced to wild-type levels by overexpression of
Gata3 revealing a role for Gata3 in prostate stem cell homeostasis. This
enforced expression of GATA3 prevented Akt activation associated with Pten
loss, which correlated with the down-regulation of Pik3cg and Pik3c2a mRNAs,
encoding respectively class I and II PI3K subunits. Remarkably, 75% of human
prostate tumors similarly show loss of active GATA3 as they progress to the
aggressive hormone-resistant stage. In addition, we identified high GATA3
expression levels in hormone-sensitive tumors (prior to castration) as a
protection factor against cancer recurrence. Together, these data establish
Gata3 as an important regulator of prostate cancer progression and point to a
role for Gata3 in stem cell potential.
139 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Role of BMP and TGF-B signaling in regulating apoptosis during limb
regeneration
2
Éric Villiard, 1Étienne Vincent, 1Jean-François Denis, 1,2Stéphane Roy
Dept. Biochemistry, Faculty of Medecine, Université de Montréal, Montréal Qc
H3T 1J4
2
Dept. of Stomatology, Faculty of Dentistry, Université de Montréal, Montreal
Qc H3T 1J4
1
The axolotl (Ambystoma mexicanum) is a vertebrate able to perfectly
regenerate its tissues. When you amputate a limb the wound closes rapidly
(approx. 2 hours). This is followed by cellular dedifferentiation & proliferation.
These initial events are referred to as the preparation phase (blastema
formation) and the repatterning of the limb is referred as the redevelopment
phase. It is known that apoptosis can be mediated by p53 which needs to be
inhibited during the preparation phase but is mandatory for redevelopment.
Interestingly, apoptosis is only observed early during regeneration which
suggests that it is not regulated by p53. In the present study, we looked at the
early apoptotic events taking place during blastema formation in the
preparation phase (3hours to 4 days) and also during the redevelopment phase
(palette stage). After determining the normal apoptotic pattern in
regeneration we blocked two central pathways and determined their effects on
apoptosis during regeneration. We used LDN 193189 to disrupt the BMP pathway
normally implicated in apoptosis in avian and mammal development. We also
used SB431542 to block the TGF-β pathway which is essential for limb
regeneration. These studies may help us get a better understanding of the role
of apoptosis during regeneration.
140 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Abnormal limb regeneration through inhibition of BMP signaling
E. Vincent1, J.-C. Guimond1, S.Roy1, 2
1
Department of Biochemistry; 2Department of Stomatology, Faculté de
Médecine Dentaire Université de Montréal, Montréal, Québec, Canada, H3T 1J4
Axolotls are capable of using mature tissue to recreate a complete limb
following amputation. After wound closure, stump cells dedifferentiate,
accumulate under the wound epithelium and proliferate to form a blastema,
eventually differentiating and forming a complete limb. This new limb is always
a continuation of the stump, without missing or additional structures. BMPs
have been identified as essential for regeneration and can even extend the
regeneration-competent region of mouse digits. We are therefore interested in
understanding their role in axolotl limb regeneration. To do this, BMP signaling
is blocked with the pharmacological inhibitor LDN193189. The phenotype
observed is dependent on both dosage and the period during which the animals
are treated. A low dosage of LDN193189 during the entire regeneration process
results in limbs missing anterior bone structures. Higher dosage can stop new
bone formation, but starting treatment later in regeneration enables proximal
bones to develop, with more bones appearing the later the treatment starts.
These results suggest that BMPs affect both patterning and bone formation
during regeneration. They also support the progressive model of regeneration
(versus the intercalation model). Genes affected during treatment by
LDN193189 will be analyzed to better understand what processes are controlled
by BMPs during regeneration.
141 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Dual Specificity MAPK Phosphatases are revealed as targets of MEF2 in
skeletal and cardiac muscle
Wales, S.1, Hashemi, S.1, Blais, A.2, and J.C. McDermott1
1
Department of Biology, York University, Toronto, Ontario; 2Ottawa Institute of
Systems Biology, University of Ottawa, Ottawa, Ontario
The differentiation of satellite “stem” cells in adult skeletal muscle is
necessary to repair damaged muscle. Transcription factor Myocyte Enhancer
Factor-2 (MEF2) is required during myogenesis however its role in satellite cellmediated muscle repair is not fully understood. Using high throughput ChIP-exo
in cultured C2C12 myogenic cells and primary cardiomyocytes novel MEF2
target genes were identified including members of the family of Dual
Specificity Phosphatases (DUSPs). DUSP6 in particular has recently been shown
to be expressed during satellite cell differentiation. Our observations confirm
that DUSP6 is a MEF2 target gene in both skeletal and cardiac muscle, however
MEF2A and MEF2D have divergent roles in each cell type. In C2C12s, DUSP6 is
able to promote myogenesis only during the early stages of differentiation,
likely due to its selective dephosphorylation of ERK1/2. Using a p38 MAPK
inhibitor it was determined that MEF2D negatively regulates DUSP6 in a p38 and
HDAC dependent manner. Furthermore MEF2D was shown to co-localize with
DUSP6 in a single myofiber culture model. These data illustrate a unique
inhibitory role of the p38-MEF2 signaling pathway which represses promyogenic DUSP6 at key stages of myogenesis and may indicate how the
biphasic activity of ERK is regulated during myogenesis. Supported by a CIHR
grant to JCM.
142 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Calibration of wide-field deconvolution microscopy for quantitative
fluorescence imaging
Lee J.S., Wee T.L, Brown C.M.
McGill University, Advanced BioImaging Facility (ABIF), 3649 Promenade Sir
William Osler, Bellini Building Rm137, Montreal, QC
Deconvolution enhances contrast in fluorescence microscopy images, especially
in low-contrast, high background wide-field microscope images, improving
characterization of features within the sample. Quantitative image analysis
requires instrument calibration and with deconvolution, necessitates that this
process itself preserves the relative quantitative relationships between
fluorescence intensities. In order to ensure that the quantitative nature of the
data remains unaltered, deconvolution algorithms need to be thoroughly
tested. This study investigated whether the iterative restorative deconvolution
and blind deconvolution algorithms in AutoQuant (Version X3, Media
Cybernetics, Rockville, MD) preserve the relative quantitative intensity data.
InSpeck green calibration microspheres were prepared for imaging, z-stacks
were taken using a wide-field microscope, and the images were deconvolved
using the default software settings. As expected, deconvolved data sets showed
higher average microsphere intensities and smaller volumes than the raw widefield data sets. In both raw and deconvolved data sets, intensity means showed
linear relationships with the relative microsphere intensities given by the
manufacturer. Importantly, upon normalization, the two trend lines were found
to have essentially the same slope. In both raw and deconvolved images, the
volumes of the microspheres were fairly uniform for all relative microsphere
intensities. In conclusion, we validated that our wide-field fluorescence
microscope is quantitative, and AutoQuant deconvolution algorithms preserve
the quantitative microsphere intensity relationship.
143 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Anillin (ANI-1) is required for neuroblast cytokinesis to non-autonomously
regulate epidermal morphogenesis in C. elegans embryos
Denise Wernike and Alisa Piekny
Concordia University, Department of Biology, Montreal, Canada
During ventral enclosure (VE), epidermal cells migrate to and adhere at the
ventral midline to cover the C. elegans embryo in an epithelium. F-actin and
the catenin/cadherin complex (CCC) regulate VE, but it is not known if myosin
is also required. Recently, we found that anillin (ANI-1), a scaffolding protein
that coordinates contractility, is required for VE, since epidermal cells fail to
properly migrate, align and/or adhere in ani-1 RNAi embryos. Interestingly,
ANI-1 is not found in epidermal cells, but is enriched in the underlying
neuroblasts. Neuroblasts fail to divide upon ANI-1 depletion, suggesting that
ani-1 regulates neuroblast cytokinesis. Furthermore, we show that the ventral
pocket closes via a purse-string driven by myosin in a neuroblast-dependent
manner, because NMY-2 localization is altered on a supracellular but not
subcellular level in ani-1 RNAi embryos. In support of ANI-1’s non-autonomous
role of VE, ani-1 RNAi enhances VE phenotypes observed in CCC mutants. Also,
overexpressing ANI-1 suppresses a-catenin lethality and vice versa further
supporting the idea that mechanotransduction between tissues is essential for
epidermal morphogenesis.
144 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
Mechanisms of reactive oxygen species-mediated longevity
Callista Yee, Wen Yang and Siegfried Hekimi
Department of Biology, McGill University
Previous research using model organisms has identified three main pathways
which can affect aging: caloric restriction, insulin/IGF-1 signalling, and
mitochondrial signalling. In C. elegans, two mutations that affect mitochondrial
electron transport chain subunits (isp-1(qm150) and nuo-6(qm200)) result in
increased production of mitochondrial reactive oxygen species (mtROS).
Animals carrying these mutations have a significantly increased lifespan
relative to the wild type. It has also been shown that treatment with prooxidants such as paraquat (PQ) can significantly increase wild type lifespan but
has no effect on the lifespan of the two mitochondrial mutants. Furthermore,
treatment with anti-oxidants such as N-acetyl-cysteine (NAC) and Vitamin C can
decrease the longevity of these mutants to the wild-type level. These and
other results suggest that increased levels of mtROS act as a signal to extend
lifespan in C. elegans.
In order to determine the mechanisms involved in mtROS longevity signalling,
we are studying changes in gene expression patterns resulting from elevated
mtROS and testing the involvement of known conserved signalling pathways
that are associated with mitochondria. Results from both approaches will be
presented.
145 7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
ONGLET 4
ATTENDEES
7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
AHLGREN, Jennifer - Instituts de recherche en santé du Canada (IRSC-CIHR)
Jennifer.Ahlgren@cihr-irsc.gc.ca
AHMADI, Moloud - McGill University
moloud.ahmadi@mail.mcgill.ca
AKIMENKO, Marie-Andrée – University of Ottawa
makimen@uottawa.ca
ALLAN, Douglas - University of British Columbia
doug.allan@ubc.ca
ALMEIDA, Stephanie - University of Toronto
stephanie.m.almeida@gmail.com
AMINI, Ranawade - Institut de recherche en immunologie et en cancérologie
(IRIC)
rana.amini@umontreal.ca
AMON, Siavash - McMaster University
amons@mcmaster.ca
ARSENAULT, Michel - University of Prince Edward Island
michars@gmail.com
BAJAJ, Megha - University of Alberta
mbajaj@ualberta.ca
BARROS, Flavia - The Hospital for Sick Children
flavia.barros@sickkids.ca
BÉLANGER, Marie-Claude - Institut de recherches cliniques de Montréal (IRCM)
marie-claude.belanger@ircm.qc.ca
BELLAICHE, Yohanns - Institut Curie - Centre de recherche
yohanns.bellaiche@curie.fr
BERGERON, Karl-F. - Université du Québec à Montréal (UQAM)
karlfbergeron@gmail.com
BHANSHALI, Forum - Institut de recherche en immunologie et en cancérologie
(IRIC)
tbhanshali@gmail.com
BILODEAU, Steve - Université Laval
Steve.Bilodeau@crchuq.ulaval.ca
BOUCHARD, Maxime - McGill University
maxime.bouchard@mcgill.ca
BROWN, David - The Hospital for Sick Children
david.d.r.brown@gmail.com
BURG, Maxwell - University of Manitoba
umburg@cc.umanitoba.ca
CAYOUETTE, Michel - Institut de recherches cliniques de Montréal (IRCM)
michel.cayouette@ircm.qc.ca
CHAN, Kevin - University of Toronto
kevin.chan@utoronto.ca
CHARRON, Frédéric - Institut de recherches cliniques de Montréal (IRCM)
frederic.charron@ircm.qc.ca
CHASTON-VICKERS, Emma - University of New Brunswick
ej.chaston.vickers@gmail.com
7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
CHILDS, Sarah - University of Calgary
schilds@ucalgary.ca
CHIN, Preston - McGill University
preston.chin@mail.mcgill.ca
CIRUNA, Brian - The Hospital for Sick Children
ciruna@sickkids.ca
CLAYCOMB, Julie - University of Toronto
julie.claycomb@utoronto.ca
COCKBURN, Katie - The Hospital for Sick Children
katiecockburn@gmail.com
COLAVITA, Antonio - Ottawa Hospital Research Institute
colavita@uottawa.ca
CÔTÉ, Jocelyne - Institut de recherches cliniques de Montréal (IRCM)
jocelyne.cote@ircm.qc.ca
CRAWFORD, Bryan - University of New Brunswick
bryanc@unb.ca
CURRIE, Ko - The Hospital for Sick Children
ko.currie@mail.utoronto.ca
DARWICH, Rami - University of Ottawa
rdarwich@uottawa.ca
DENIS, Jean-François - Université de Montréal
jean-francois.denis@umontreal.ca
DENNIS, Daniel - University of Calgary
ddennis@ucalgary.ca
DERRY, Brent - The Hospital for Sick Children
brent.derry@sickkids.ca
DESCOTEAUX, Catherine - Institut de recherche en immunologie et en
cancérologie (IRIC)
catherine.descoteaux@umontreal.ca
DESJARDINS, David - McGill University
david.desjardins2@mail.mcgill.ca
DICKSON, Ben - University of Western Ontario
bdickso3@uwo.ca
DOEL, Joey - University of Western Ontario
gdeol3@uwo.ca
DOLIQUE, Tiphaine - Institut de recherches cliniques de Montréal (IRCM)
tiphaine.dolique@ircm.qc.ca
DROUIN, Jacques - Institut de recherches cliniques de Montréal (IRCM)
jacques.drouin@ircm.qc.ca
DRYSDALE, Thomas - University of Western Ontario
tadrysda@uwo.ca
D'SOUZA, Serena - University of Toronto
serena.dsouza@utoronto.ca
EAMES, Brian F. - University of Saskatchewan
b.frank@usask.ca
7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
ELLIS, Tonya - University of New Brunswick
n76b9@unb.ca
EMERY, Grégorie - Institut de recherche en immunologie et en cancérologie
(IRIC)
gregory.emery@umontreal.ca
ESPARZA DE NINO, Blanca - University of Prince Edward Island
Besparzagons@upei.ca
FAGOTTO, François - McGill University
francois.fagotto@mcgill.ca
FAIRCHILD, Michael - University of British Columbia
michael.j.fairchild@gmail.com
FALLATA, Amina - University of New Brunswick
afallata-404@hotmail.com
FENG, Qingping - University of Western Ontario
qfeng@uwo.ca
FENG, Shengrui - University of Ottawa
sfeng024@uottawa.ca
FOGARTY, Lauren - University of Newfoundland
lauren.fogarty@mun.ca
FRASER, Andrew - University of Toronto
andy.fraser@utoronto.ca
GAUTHIER, Kimberley - McGill University
kimberley.gauthier@mail.mcgill.ca
GENTILE, Claudia - Institut de recherches cliniques de Montréal (IRCM)
claudia.gentile@ircm.qc.ca
GERHOLD, Abigail - Institut de recherche en immunologie et en cancérologie
(IRIC)
abigail.gerhold@umontreal.ca
GHARIBEH, Lara - University of Ottawa
lghar051@uottawa.ca
GOLDBERG, Hannah - University of Western Ontario
hgoldbe3@uwo.ca
GOUPIL, Eugénie - Institut de recherche en immunologie et en cancérologie
(IRIC)
eugenie.goupil@umontreal.ca
GRANTS, Jennifer - University of British Columbia
jgrants@cmmt.ubc.ca
HACHÉ, Étienne - University of New Brunswick
g84ny@unb.ca
HAMOUD, Noumeira - Institut de recherches cliniques de Montréal (IRCM)
noumeira.hamoud@ircm.qc.ca
HARDTKE, Christian - Université de Lausanne
Christian.Hardtke@unil.ch
HARTWIG, Sunny - University of Prince Edward Island
shartwig@upei.ca
7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
HARTWIG, Daniel - University of Prince Edward Island
shartwig@upei.ca
HIETER, Philip – University of British Columbia
hieter@msl.ubc.ca
HEKIMI, Siegfried - McGill University
siegfried.hekimi@mcgill.ca
HIPFNER, David - Institut de recherches cliniques de Montréal (IRCM)
david.hipfner@ircm.qc.ca
HOODLESS, Pamela - British Columbia Cancer Agency
hoodless@bccrc.ca
HOPYAN, Sevan - The Hospital for Sick Children
sevan.hopyan@sickkids.ca
HUANG, Peng - University of Calgary
huangp@ucalgary.ca
HUI, Chi Chung - The Hospital for Sick Children
cchui@sickkids.ca
IBHAZEHIEBO, Kingsley - University of Calgary
kibhazeh@ucalgary.ca
IM, Michelle - University of Western Ontario
mim2@uwo.ca
IULIANELLA, Angelo - Dalhousie University
angelo.iulianella@dal.ca
JACKSON, Bradley - University of Western Ontario
bjacks8@uwo.ca
JENNA, Sarah - Université du Québec à Montréal (UQAM)
jenna.sarah@uqam.ca
KADEKAR, Pratik - McGill University
pratik.kadekar@mail.mcgill.ca
KANIA, Artur - Institut de recherches cliniques de Montréal (IRCM)
artur.kania@ircm.qc.ca
KARUNATILLEKE, Nadun - Dalhousie University
nadun.karunatilleke@dal.ca
KASHKOOLI, Leily - McGill University
leily.kashkooli@mail.mcgill.ca
KAZANETS, Anna - McGill University
anna.kazanets@mail.mcgill.ca
KEOW, Jonathan - University of Ottawa
jkeow021@uottawa.ca
KHARAGHANI, Sahar - University of Western Ontario
skharag@uwo.ca
KHETCHOUMIAN, Konstantin - Institut de recherches cliniques de Montréal
(IRCM)
konstantin.khetchoumian@ircm.qc.ca
KHERDJEMIL, Yacine - Institut de recherches cliniques de Montréal (IRCM)
yacine.kherdjemil@ircm.qc.ca
7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
KIM, Shinhye - University of Manitoba
kims3410@myumanitoba.ca
KLIMOV, Eugene - University of Western Ontario
eklimov@uwo.ca
KMITA, Marie - Institut de recherches cliniques de Montréal (IRCM)
marie.kmita@ircm.qc.ca
KORMISH, Jay - University of Manitoba
jay.kormish@umanitoba.ca
KRAUSE, Henry - University of Toronto
h.krause@utoronto.ca
LACOMME, Marine - Institut de recherches cliniques de Montréal (IRCM)
marine.lacomme@ircm.qc.ca
LALONDE, Robert - University of Ottawa
robertl.lalonde@gmail.com
LAPRISE, Patrick - Centre de recherche-Centre hospitalier Universitaire
de Québec
patrick.laprise@crhdg.ulaval.ca
LAVICTOIRE, Melissa - University of Ottawa
melissa.l.lavictoire@gmail.com
LAW, Chris - Institut de recherches cliniques de Montréal (IRCM)
chris.law@ircm.qc.ca
LEBLOND, Éric – Illimina Inc.
eleblond@illumina.com
LECUIT, Thomas – Institut de biologie du développement de Marseilles
thomas.lecuit@univ-amu.fr
LEFEBVRE, Julie - The Hospital for Sick Children
julie.lefebvre@sickkids.ca
LEPELLETIER, Lea - Institut de recherches cliniques de Montréal (IRCM)
lea.lepelletier@ircm.qc.ca
LEUNG, Vicki - McGill University
vicki.leung@mail.mcgill.ca
LIN, Alexander - The Hospital for Sick Children
alexander.lin@utoronto.ca
LINK, Brian - Medical College of Wisconsin
blink@mcw.edu
LIPSHITZ, Howard - University of Toronto
howard.lipshitz@utoronto.ca
LIU, Yanli - University of Toronto
yanliliu81@gmail.com
LIU, Ke - University of Toronto
keliu2010@gmail.com
LOEWEN, Royden (Sacha) - University of Manitoba
loewenra@myumanitoba.ca
LUXEY, Maeva - Institut de recherches cliniques de Montréal (IRCM)
maeva.luxey@ircm.qc.ca
7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
MARIOTTI, Alexa - Concordia University
a.mariotti@live.ca
MAYRAN, Alexandre - Institut de recherches cliniques de Montréal (IRCM)
alexandre.mayran@ircm.qc.ca
MCCONKEY, Haley - University of Western Ontario
hmcconk@uwo.ca
MCGHEE, James - University of Calgary
jmcghee@ucalgary.ca
MCMASTER, Christopher - Dalhousie University
christopher.mcmaster@dal.ca
MCMILLAN, Stephanie - University of Ottawa
stephanie.c.mcmillan@gmail.com
MENDOZA, Meg - The Hospital for Sick Children
megmendo@gmail.com
MENG, Jassy - McGill University
jassy.meng@gmail.com
MIN, Jinrong - University of Toronto
jr.min@utoronto.ca
MONAT-RELIAT, Carine - Institut de recherches cliniques de Montréal (IRCM)
carine.monat@ircm.qc.ca
NARBONNE, Patrick - Institut de recherche en immunologie et en cancérologie
(IRIC)
patrick.narbonne@umontreal.ca
NEMEC, Stephen - Institut de recherches cliniques de Montréal (IRCM)
stephen.nemec@ircm.qc.ca
NUTTER, Lauryl - The Hospital for Sick Children
lauryl.nutter@sickkids.ca
OUELLETTE, Marie-Hélène - Université du Québec à Montréal (UQAM)
marie.hln@gmail.com
PACKARD, Adam - Columbia University
aip2117@columbia.edu
PATEL, Nipam H. - Berkeley University
nipam@uclink.berkeley.edu
PATRIQUEN, Ashley - University of Prince Edward Island
apatriquen@upei.ca
PEARSON, Bret – University of Toronto
bret.pearson@utoronto.ca
PELLETIER, Audrey - Institut de recherches cliniques de Montréal (IRCM)
audrey.pelletier@ircm.qc.ca
PILON, Nicolas - Université du Québec à Montréal (UQAM)
pilon.nicolas@uqam.ca
PULICHINO, Anne-Marie - Université Laval
anne-marie.pulichino@vrr.ulaval.ca
RABICKI, Katherine - University of Western Ontario
krabicki@uwo.ca
7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
RABILOTTA FAURE, Alexia - Institut de recherche en immunologie et
en cancérologie (IRIC)
alexia_faure@hotmail.com
RACHUBINSKI, Richard - University of Alberta
rick.rachubinski@ualberta.ca
RAJGARA, Rashida - University of Ottawa
iskerjan@uottawa.ca
RANAWADE, Ayus - McMaster University
ranawaav@mcmaster.ca
RAZA, Qamber - McMaster University
halish_day@hotmail.com
ROBERTSON, Stéphanie - Instituts de recherche en santé du Canada
(IRSC-CIHR)
Stephanie.Robertson@cihr-irsc.gc.ca
ROBITAILLE, Johanne - Dalhousie University
jrobitai@dal.ca
ROCHELEAU, Christian - McGill University
christian.rocheleau@mcgill.ca
ROSSI, Fabio - University of British Columbia
fabio@brc.ubc.ca
ROWLAND, Megan - University of Western Ontario
mrowlan7@uwo.ca
ROY, Richard - McGill University
richard.roy@mcgill.ca
ROY, Simon - New England Biolab
roy@neb.com
ROY, Stéphane - Université de Montréal
stephane.roy@umontreal.ca
RYAN, Aimée - McGill University
aimee.ryan@mcgill.ca
SADER, Fadi - Université de Montréal
fadi.sader@umontreal.ca
SAGHATELYAN, Armen - Université Laval
Armen.Saghatelyan@crulrg.ulaval.ca
SAMUEL, Mark - Université de Montréal
mark.e.samuels@umontreal.ca
SANCHEZ-FERRAS, Oraly - Université du Québec à Montréal (UQAM)
oralysanchez@gmail.com
SCHMEISSER, Sebastian - McGill University
sebastian.schmeisser@mail.mcgill.ca
SEETHARAMAN, Ashwin - University of Toronto
ashvenkat@gmail.com
SELLERI, Licia - Cornell University
lis2008@med.cornell.edu
SHAFER, Maxwell - McGill University
max.shafer@gmail.com
7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
SHARMA, Richa - McGill University
richa.sharma@mail.mcgill.ca
SHETH, Rushikesh - Institut de recherches cliniques de Montréal (IRCM)
rushikesh.sheth@ircm.qc.ca
SIMARD, Martin - Centre de recherche-Centre hospitalier universitaire
de Québec
martin.simard@crhdq.ulaval.ca
SINGH, Randeep - University of Western Ontario
rsingh25@uwo.ca
SMALL, Christopher - University of New Brunswick
c.small@unb.ca
SONG, Audrey Mideum - McGill University
mideum.song@mail.mcgill.ca
SORET, Rodolphe - Université du Québec à Montréal (UQAM)
rode440@gmail.com
SRAYKO, Martin - University of Alberta
srayko@ualberta.ca
STERN, Claudio - University College London
c.stern@ucl.ac.uk
STEWART, Katie - McGill University
katherine.stewart2@mail.mcgill.ca
SULL, Alexandra - University of Western Ontario
asull@uwo.ca
SULL, Judith - University of Western Ontario
jsull2@uwo.ca
SUN, Margaret Man-Ger - University of Western Ontario
msun33@uwo.ca
SZABO, Nora - Institut de recherches cliniques de Montréal (IRCM)
nora.szabo@ircm.qc.ca
TACHIBANA, Nobuhiko - University of Calgary
ntachiba@ucalgary.ca
TAKAHASHI, Hideto - Institut de recherches cliniques de Montréal (IRCM)
hideto.takahashi@ircm.qc.ca
TAMMING, Renée - University of Western Ontario
rtamming@uwo.ca
TANENTZAPF, Guy - University of British Columbia
tanentz@interchange.ubc.ca
TEGHA DUNGHU, Justus - University of Alberta
teghadun@ualberta.ca
TOBIAS, Ian - University of Western Ontario
itobias@uwo.ca
TOURÉ, Aboubacrine - Université du Québec à Montréal (UQAM)
a_toure@rocketmail.com
TREMBLAY, Mathieu - McGill University
mathieu.tremblay5@mcgill.ca
7e Conférence canadienne de biologie du développement / 7th CDBC
& 5e Conférence régionale Canada de la SDB / 5th Canada Regional SDB Conference
TROPEPE, Vincenzo - University of Toronto
v.tropepe@utoronto.ca
VANDERLUIT, Jacqueline - University of Newfoundland
j.vanderluit@mun.ca
VILLIARD, Éric - Université de Montréal
eric.villiard@umontreal.ca
VINCENT, Étienne - Université de Montréal
et_vince@hotmail.com
WALES, Stephanie - York University
swales@yorku.ca
WEE, Erika - McGill University
erika.wee@mcgill.ca
WERNIKE, Denise - Concordia University
denise.wernike@gmail.com
YEE, Callista - McGill University
callista.yee@mail.mcgill.ca
ZETKA, Monique - McGill University
monique.zetka@mcgill.ca
ZHEN, Mei - University of Toronto
zhen@lunenfeld.ca