Cell-cell Communications
in Development
Induction and Competence



What do we mean
by induction?
How do we
define
competence?
Where does Pax6
fit in?
Induction and Competence

Where can we observe reciprocal
inductions?
Induction and Competence
 What
is the difference between
instructive and permissive
interactions?
Epithelial-mesenchymal
interactions

How does this diagram illustrate the
regional specificity of induction?
Epithelial-mesenchymal
interactions

How does this experiment illustrate the
genetic specificity of induction?
Paracrine Factors in Development

What is the connection between paracrine
factors and induction?
Paracrine Factors in Development

How do fibroblast growth factors (FGF’s)
induce changes in cells?
Paracrine Factors in Development

What is the Hedgehog family?
Paracrine Factors in Development

The wnt family?
Paracrine Factors in Development

The TGF-β
superfamily?
Signal Transduction Pathways
 What
is involved in signal
transduction?
Signal Transduction Pathways

How does the RTK pathway promote cellcell induction?
Signal Transduction Pathways

What are examples of some specific
inductions that use the RTK pathway?
Signal Transduction Pathways

How does the Smad pathway compare
with the RTK pathway?
Signal Transduction Pathways

What pathway mediates both the
differentiation of blood cells and the
formation of milk for lactation?
Signal Transduction Pathways


How can the Wnt
pathway mediate
cell division?
What are the
ramifications of
this pathway?
Signal Transduction Pathways

How does the sonic hedgehog paracrine
factor influence limb and neural
development in vertebrates?
Signal Transduction Pathways


What happens in
the absence of
sonic hedgehog?
How is cholesterol
involved here?
Cell Death Pathways
 What
is the difference between
apoptosis and necrosis?
 Why
is apoptosis critical for
development?
 What
initiates apoptosis?
Cell Death Pathways

What role has C. elegans played in our
knowledge of apoptosis?
Juxtacrine Signaling
 How
is this type of signaling different
from paracrine signaling?
– signal molecule is a protein that resides
in adjacent cell member
Juxtacrine Signaling
Juxtacrine Signaling

Ligand resides in
extracellular matrix
of signaling cell
– fibronectin
– laminin

What kinds of
receptors are
involved?
Juxtacrine Signaling

Gene activation by
matrix attachment
Juxtacrine Signaling
– signal transmitted
from cytoplasm of
one cell directly to
cytoplasm of
second cell
– use gap junction
Pathway’s Cross Talk


transcription may
require activation
of two pathways
one receptor can
activate different
pathways
Maintaining Differentiation

Transcription factor as its own enhancer
Maintaining Differentiation

Prevent nucleosome formation
Maintaining Differentiation

Autocrine stimulation
Maintaining Differentiation

Paracrine loop