SCRIPPS FLORIDA SCIENTIFIC REPORT
FOR THE YEAR ENDING JUNE 30, 2015
PART I – GRANT AWARDS AND SCIENTIFIC ACHIEVEMENTS
A. NEW GRANTS
Scripps Research Institute Scientists Awarded $7.9 Million to Develop Artificial Immune
System
Scientists from both campuses of The Scripps Research Institute (TSRI) have been awarded a total
of $7.9 million from the Defense Advanced Research Projects Agency (DARPA) of the U.S.
Department of Defense. The two teams will build what is, in essence, an artificial immune system,
comprising vast “libraries” of different types of molecules from which will emerge individual
compounds to detect or neutralize an array of biological and chemical threats.
Under the auspices of DARPA’s new Fold F(x) Program, the Jupiter, Florida team, led by
Professor Tom Kodadek and Assistant Professor Brian Paegel, will receive $5.7 million; the La
Jolla, California team, led by Professor Floyd Romesberg, will receive $2.2 million.
Developing New Libraries
In Jupiter, Kodadek, Paegel and their colleagues will develop libraries of functional compounds
and engineer highly automated strategies for rapid synthesis, screening and production. These
libraries will contain molecules each tagged with a DNA “barcode” that uniquely identifies the
molecules’ chemical structure. “We hope to create chemical libraries and screening platforms that
are truly revolutionary in their capabilities,” Kodadek said.
For Paegel, the DARPA grant will expand his lab’s current program in drug discovery technology
development. His team has developed a microfluidic circuit that screens single compounds
suspended on artificial beads, processing more than 200,000 compounds in a matter of hours. “We
envision next-generation small molecule discovery as a distributed enterprise, not just limited to
facilities like our molecular screening center in Jupiter,” Paegel said. “Our ultra-miniaturized
approach will make this vision a reality.”
Evolving New Functions
In La Jolla, Romesberg and his colleagues will develop variants of oligonucleotides—short, singlestranded DNA or RNA molecules—modified to be both stable and to have increased functionality.
The team will leverage a system known as SELEX (Systematic Evolution of Ligands by
Exponential Enrichment) to evolve novel function molecules. “We plan to modify the classical
SELEX methodology with two innovations from our previous work,” Romesberg said.
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The first innovation, developed by Tingjian Chen, a postdoctoral fellow in the Romesberg lab, is a
DNA polymerase evolved to recognize nucleotides with modified sugars, which impart the
corresponding oligonucleotide polymers with increased thermal stability and resistance to enzymes
that typically degrade oligonucleotides.
The second innovation is an unnatural base pair, developed as part of the team’s recent expansion
of the genetic alphabet, which can be modified with linkers to site-specifically attach different
functionality to oligonucleotides. The combined technologies should allow for the evolution of
novel biopolymers that are both stable and possess virtually any desired binding or catalytic
activity.
Scripps Florida Scientists Awarded $3.5 Million to Expand Development of New Diabetes
Therapies
Scientists from the Florida campus of The Scripps Research Institute (TSRI) have been awarded
$3.5 million from the National Institute of Diabetes and Digestive and Kidney Diseases of the
National Institutes of Health to accelerate development of a new class of anti-diabetic compounds.
Patrick R. Griffin, chair of the Department of Molecular Therapeutics at Scripps Florida and a leader
in the field, is the principal investigator of the new five-year grant.
“Effective management of diabetes and the complications associated with the disease remains a
significant medical challenge,” Griffin said. “Due to significant safety concerns, a class of drugs that
have proven effective at improving the body’s response to insulin (insulin sensitizers known as
glitazones) has essentially been removed from the arsenal of therapeutics used to treat type 2
diabetes.”
Over the past decade, the Griffin lab along with the Kamenecka lab has focused on the molecular
details of the mode of action of insulin sensitizers. Using this information, the scientists have made
significant advances in developing drug candidates targeting a receptor known as peroxisome
proliferator-activated receptors gamma (PPARG). These drug candidates inhibit the receptor, a
unique mode of action compared to the glitazones.
Diabetes affects more than 29 million people in the United States, according to the American
Diabetes Association 2012 report. Between 2010 and 2012, the incidence rate was about 1.7-1.9
million per year, and in 2013, the estimated direct medical costs were $176 billion.
This new award will fund deep dissection of the molecular mechanism of the new class of
compounds developed at TSRI, and this information will help pave the path toward clinical
development.
In addition, the Griffin lab, in collaboration with researchers at the University of Toledo, will look at
the effects of these compounds on bone, an emerging safety issue with the glitazones.
The number of the new grant is 1R01DK105825.
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Scripps Florida Scientists Win $3.3 Million Grant to Accelerate Development of Treatments
for Intellectual Disability, Autism, Epilepsy
Scientists from the Florida campus of The Scripps Research Institute (TSRI) have been awarded
$3.3 million by the National Institutes of Health (NIH) to identify biomarkers to accelerate drug
development for disorders including autism spectrum disorder, epilepsy and some types of
intellectual disability.
Gavin Rumbaugh, a TSRI associate professor, is the principal investigator of the new five-year
project.
“Our long-term goal is to increase the success rate of therapies translated from animal models to
patients,” Rumbaugh said. “By validating biomarkers in mice and using this information in
combination with pharmacological or genetic treatment strategies, we hope to create a set of tools
and methods that can be used successfully to develop new therapeutics.”
Rumbaugh has been a pioneer in the study of Syngap1, one of the most commonly disrupted genes in
patients with sporadic developmental disorders of the brain. His work in animal models has shown
that life-long cognitive disruptions are caused by isolated damage to developing neurons in the
forebrain (in humans, the forebrain is responsible for higher cognitive processes, such as language
and reasoning).
Rumbaugh and his colleagues plan to validate several highly quantifiable biomarkers of brain
damage that occur in these animal models during a critical period of early development. Because
abnormal cognition in these models can be traced to this early developmental window, these
measures have the potential to provide a roadmap of cognitive ability to guide drug design.
The number of the grant, from the NIH’s National Institute of Mental Health, is 1R01MH108408.
Scripps Florida Scientists Win $2.4 Million to Expand Development of New Pain Therapies
Scientists from the Florida campus of The Scripps Research Institute (TSRI) have been awarded
$2.4 million from the National Institute on Drug Abuse of The National Institutes of Health to
expand development of new pain medications with fewer side effects than those currently available.
TSRI Professor Laura Bohn, who has been a leader in the development of pain therapies, will be the
principal investigator of the new five-year grant.
“We are developing substitutes for narcotic pain killers with less risk for overdose and fewer side
effects,” Bohn said. “The new grant enables us to study how these potential drugs, which utilize the
same biological target as morphine, fundamentally differ from the current pain medications in how
they engage neuronal signaling.”
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Adverse side effects of current opioid drugs such as morphine and oxycodone can be serious and
include respiratory suppression, constipation and addiction. According to the U.S. Centers for
Disease Control, nearly two million Americans abused prescription painkillers in 2013; almost 7,000
people are treated each day in hospital emergency rooms for abuse of these drugs.
While the new compounds under development activate the same receptor as morphine—the mu
opioid receptor or MOR—they do so in a way that avoids recruiting the protein beta-arrestin 2.
Genetic studies have shown that animal models lacking beta-arrestin 2 experience robust pain relief
with diminished side effects.
“The difference in the way that these new compounds work results in greater pain relief without as
much respiratory suppression (overdose risk) and persistent constipation in preclinical studies,” said
Bohn. “We are hoping to dial out dependence liabilities as we pursue bringing these drugs to clinical
trials.”
The number of the new grant is 1R01DA038964.
Scripps Florida Scientists Win Grant to Uncover Ways to Erase Toxic PTSD Memories
Scientists from the Florida campus of The Scripps Research Institute (TSRI) have been awarded
$2.3 million from the Department of Health and Human Services of the National Institutes of Health
to better understand how memories are stored in the hopes of eventually being able to treat
posttraumatic stress disorder (PTSD) by erasing traumatic memories without altering other, more
benign ones.
Courtney Miller, a TSRI associate professor, is the principal investigator for the new five-year study.
“We hope this new study will make a significant contribution to the goal of developing new and
more effective treatments for mental illness,” Miller said.
While literally thousands of mechanisms for how a memory initially forms have been identified,
only a few mechanisms are known for how the brain stores these memories for weeks to years. To
produce a memory, a lot has to be done, including the alteration of the structure of nerve cells via
changes in the dendritic spines—small bulb-like structures that receive electrochemical signals from
other neurons. Normally, these structural changes occur via actin, the protein that makes up the
infrastructure of all cells.
Miller is investigating the possibility that microRNAs, naturally occurring small RNAs that act to
suppress the production of proteins, may be capable of coordinating the complexity required for the
brain to maintain this actin-based structural integrity of a long-lasting memory.
“Our study will investigate the microRNA profile of a PTSD-like memory, with the idea that the
persistence of a traumatic memory is maintained by the recruitment of a unique set of microRNAs
within the amygdala—the brain’s emotional memory center and a critical participant in PTSD,”
Miller said.
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An understanding of how the brain actually stores these toxic memories should result in the
development of new targets that can then be exploited to selectively target harmful memories, as in
the case of PTSD, or to preserve fading memory, such as with age-related cognitive decline.
In 2013, Miller and her colleagues were able to erase dangerous memories associated with drugs of
abuse in mice and rats, without affecting other more benign memories. That surprising discovery,
published in the journal Biological Psychiatry pointed to a clear and workable method to disrupt
unwanted memories while leaving others intact.
The number of the new grant is 1R01MH105400.
Scripps Florida Scientists Win $2.2 Million to Expand Study of Innovative Obesity Therapy
Scientists from the Florida campus of The Scripps Research Institute (TSRI) have been awarded
nearly $2.2 million by the National Institute of Diabetes and Digestive and Kidney Diseases of the
National Institutes of Health (NIH) to advance an innovative approach to the treatment of obesity, a
serious health problem that affects more than one-third of all Americans.
Anutosh Chakraborty, a TSRI assistant professor, is the principal investigator of the new five-year
project.
Obesity, especially when combined with type 2 diabetes, leads to conditions including coronary
heart disease, stroke, hypercholesterolemia, fatty liver, sleep apnea, osteoarthritis, certain cancers
and various other diseases. If current trends continue, the number of Americans who are obese could
reach 50 percent by 2030, according to the Trust for America's Health and the Robert Wood Johnson
Foundation. According to Britain’s Fiscal Times, the estimated cost of obesity in the United States is
already $305.1 billion annually. Current medications have limited success.
In an effort to address this dilemma, scientists want to identify relevant proteins, especially enzymes,
to target with new and more effective drug candidates.
“Anti-obesity drugs generally work on reducing how much you eat or absorb,” Chakraborty said.
“We investigate the problem from a different perspective.”
Chakraborty and his colleagues discovered that an enzyme called inositol hexakisphosphate kinase-1
(IP6K1) plays a significant role in promoting the action of insulin on energy/fat storage. Mice
without IP6K1 are not only lean on regular chow diet, they are also protected against high-fat-dietinduced obesity and insulin resistance.
“IP6K1 knockout mice eat a similar amount of food, yet are lean as they efficiently expend the extra
energy,” he said. “For us, that means that IP6K1 is the regulating factor when it comes to energy
storage. Conversely, abnormal regulation of IP6K1 leads to obesity and insulin resistance. The new
grant will allow us to identify the underlying mechanisms of how it works.”
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In addition to gaining a broader understanding of the fundamental mechanism by which IP6K1
regulates metabolism, Chakraborty and his colleagues—including Scripps Florida’s Ted
Kamenecka, assistant professor and associate scientific director of the Translational Research
Institute, and Michael Cameron, associate professor of molecular therapeutics and DMPK—are
working on the development of drugs which are expected to treat obesity, type 2 diabetes and other
metabolic diseases via IP6K1 inhibition.
The number of the grant is 1R01DK103746-01A1.
Scripps Florida Scientists Win $2.1 Million to Study Protein Linked to Parkinson’s Disease
Scientists from the Florida campus of The Scripps Research Institute (TSRI) have been awarded
$2.1 million from the National Institute of Neurological Disorders and Stroke of The National
Institutes of Health (NIH) to study a protein that has been closely linked in animal models to
Parkinson’s disease and Huntington’s disease.
TSRI Assistant Professor Srinivasa Subramaniam will be the principal investigator of the new fiveyear grant.
The focus of the new study is a multifunctional protein known as rapamycin (mTOR), which is
involved in embryonic development, cancer and diabetes. Malfunction in mTOR activity—either too
much or too little—has also been linked to a variety of brain dysfunctions such as epilepsy, mental
retardation, Huntington’s disease and Parkinson’s disease.
In the new project, the researchers will use a wide variety of techniques to examine the role and
regulation of this protein in a brain region called the striatum, which controls motor, psychiatric and
cognitive functions.
“Even though mTOR is widely expressed throughout the body, its brain-specific regulation and
function remain unclear,” Subramaniam said. “While we know that inhibiting mTOR protects
against symptoms of Huntington’s and Parkinson’s diseases in animal models, the new grant will
help us answer two critical questions: ‘How is mTOR regulated, and what happens when it is
depleted selectively in the striatum?’ ”
Subramaniam’s long-term goal is to understand the system well enough to advance new therapies.
The number of the grant is 1R01NS087019.
Scripps Florida Scientists Win $1.5 Million Grant to Develop New Cancer Drugs
Scientists from the Florida campus of The Scripps Research Institute (TSRI) have been awarded a
$1.5 million grant from the National Institutes of Health (NIH) to develop drug candidates that could
treat cancer and neurodegenerative disease.
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Derek Duckett, a TSRI associate professor of molecular therapeutics, is the co-principal investigator
for the three-year study, along with John Cleveland of the Moffitt Cancer Center in Tampa, Florida.
Duckett, Cleveland and their teams will look for compounds that affect a key enzyme involved in the
degradation and ultimate recycling of damaged cellular material.
This process, called “autophagy,” is an ancient, cannibalistic (literally “self-eating”) pathway that
acts as the main recycling center of all cells. In autophagy, bulk cytoplasmic material and aged or
damaged organelles are recycled via the lysosome to recoup essential building blocks and adenosine
triphosphate (ATP) as a survival strategy during times of stress or nutrient limitation. Autophagy is
an important cell survival pathway, and any defects in its regulation can lead to a variety of
disorders, including neurodegenerative disorders, liver disease and cancer.
The study is focused on targeting a particular enzyme, UNC-51-like kinase-1 (Ulk1), a critical on-off
switch that regulates this pathway.
“Using these funds, we will identify new inhibitors of Ulk1,” Duckett said. “Developing selective
molecular probes that function as Ulk1-specific inhibitors would improve our understanding of the
autophagy pathway, its relationship to cancer and its utility as a target that could augment
conventional or targeted anti-cancer treatments.”
Duckett and his colleagues plan to use the high-throughput screening facilities at Scripps Florida and
the Scripps Drug Discovery Library and its 650,000-plus library of small-molecule compounds.
The number of the new grant from the NIH National Institute of General Medical Sciences is
1R01GM113972.
Scripps Florida Scientists Awarded $1.2 Million to Find Drug Candidates that Could Treat a
Wide Range of Cancers
Scientists from the Florida campus of The Scripps Research Institute (TSRI) have been awarded
$1.2 million from the National Cancer Institute of the National Institutes of Health (NIH) to
accelerate the development of drug candidates to curb one of the most important drivers of human
cancer.
TSRI Associate Professors Joseph Kissil and Louis Scampavia will be co-principal investigators for
the three-year grant, which will focus on the “Hippo-YAP signaling pathway.”
“This pathway, which was discovered less than a decade ago, appears to regulate processes that are
closely linked to an increasing number of cancers,” Kissil said. “The more we study it, the more we
see its involvement. This new grant will help expand our investigation.”
The Hippo-YAP signaling pathway has been found active in breast, colorectal and liver cancers, in
hepatocellular and squamous cell carcinoma, and in melanoma of the eye. Cancers initiated through
this pathway tend to thrive and proliferate, relatively immune to destruction from programmed cell
death.
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Kissil, Scampavia and their colleagues plan to use Scripps Florida’s ultra-high-throughput screening
resources and the campus’s library of more than 600,000 compounds to develop a series of screens
to identify and optimize compounds to target the pathway and combat cancer.
The number of the grant is 1R01CA184277.
B. SCIENTIFIC ACCOMPLISHMENTS
Scripps Florida Scientists Uncover New Compounds that Could Affect Circadian Rhythm
Scientists from the Florida campus of The Scripps Research Institute (TSRI) have discovered a
surprising new role for a pair of compounds—which have the potential to alter circadian rhythm, the
complex physiological process that responds to a 24-hour cycle of light and dark and is present in
most living things.
At least one of these compounds could be developed as a chemical probe to uncover new therapeutic
approaches to a range of disorders, including diabetes and obesity.
The study, which was published online ahead of print by the Journal of Biological Chemistry,
focuses on a group of proteins known as REV-ERBs, a superfamily that plays an important role in
the regulation of circadian physiology, metabolism and immune function.
The new study shows that the two compounds, cobalt protoporphyrin IX (CoPP) and zinc
protoporphyrin IX (ZnPP), bind directly to REV-ERBs.
REV-ERBs are normally regulated by heme, a molecule that binds to hemoglobin, helps transport
oxygen from the bloodstream to cells and plays a role in producing cellular energy. While heme
activates REV-ERB, CoPP and ZnPP inhibit it.
“These compounds are like heme, but when you swap out their metal centers their functions are
different,” said Doug Kojetin, a TSRI associate professor who led the study. “This makes us think
that the key is the chemistry of the metal ion itself. Altering the chemistry of this metal center may
be an opportune way to target REV-ERB for diabetes and obesity.”
Kojetin and his colleagues recently demonstrated that synthetic REV-ERB agonists, like the new
compounds, reduce body weight in mice that were obese due to diet.
The first authors of the study, “Structure of REV-ERB_ Ligand-binding Domain Bound to a
Porphyrin Antagonist,” are Edna Matta-Camacho of McGill University, Montreal and Subhashis
Banerjee of the University of Texas Southwestern Medical Center. Other authors of the study
include Travis S. Hughes and Laura A. Solt of TSRI; and Yongjun Wang and Thomas P. Burris of
St. Louis University School of Medicine.
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The work was supported by the National Institutes of Health (grants DK080201 and DK101871), the
James and Esther King Biomedical Research Program from the Florida Department of Health (grant
1KN-09) and the State of Florida.
The work can be accessed at
http://www.jbc.org/content/early/2014/05/28/jbc.M113.545111.full.pdf+html?sid=bef6d5e6-a7dd4ca5-9f57-6fba6122a6b5
Scripps Florida Scientists Shed New Light on Nerve Cell Growth
Amidst the astounding complexity of the billions of nerve cells and trillions of synaptic connections
in the brain, how do nerve cells decide how far to grow or how many connections to build? How do
they coordinate these events within the developing brain?
In a new study, scientists from the Florida campus of The Scripps Research Institute (TSRI) have
shed new light on these complex processes, showing that a particular protein plays a far more
sophisticated role in neuron development than previously thought.
The study, published in the journal PLOS Genetics, focuses on the large, intracellular signaling
protein RPM-1 that is expressed in the nervous system. TSRI Assistant Professor Brock Grill and his
team show the surprising degree to which RPM-1 harnesses sophisticated mechanisms to regulate
neuron development.
Specifically, the research sheds light on the role of RPM-1 in the development of axons or nerve
fibers—the elongated projections of nerve cells that transmit electrical impulses away from the
neuron via synapses. Some axons are quite long; in the sciatic nerve, axons run from the base of the
spine to the big toe.
“Collectively, our recent work offers significant evidence that RPM-1 coordinates how long an axon
grows with construction of synaptic connections,” said Grill. “Understanding how these two
developmental processes are coordinated at the molecular level is extremely challenging. We’ve
now made significant progress.”
Putting Together the Pieces
The study describes how RPM-1 regulates the activity of a single protein known as DLK-1, a protein
that regulates neuron development and plays an essential role in axon regeneration. RPM-1 uses
PPM-2, an enzyme that removes a phosphate group from a protein thereby altering its function, in
combination with intrinsic ubiquitin ligase activity to directly inhibit DLK-1.
“Studies on RPM-1 have been critical to understanding how this conserved family of proteins
works,” said Scott T. Baker, the first author of the study and a member of Grill’s research team.
“Because RPM-1 plays multiple roles during neuronal development, you wouldn’t want to interfere
with it. But exploring the role of PPM-2 in controlling DLK-1 and axon regeneration could be
worthwhile—and could have implications in neurodegenerative diseases.”
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The Grill lab has also explored other aspects of how RPM-1 regulates neuron development. A
related study, also published in PLOS Genetics, shows that RPM-1 functions as a part of a novel
pathway to control β-catenin activity—this is the first evidence that RPM-1 works in connection
with extracellular signals, such as a family of protein growth factors known as Wnts, and is part of
larger signaling networks that regulate development. A paper in the journal Neural Development
shows that RPM-1 is localized at both the synapse and the mature axon tip, evidence that RPM-1 is
positioned to potentially coordinate the construction of synapses with regulation of axon extension
and termination.
In addition to Grill and Baker, Erik Tulgren of the University of Minnesota, Willy Bienvenut of the
Campus de Recherche de Gif, France, as well as Karla Opperman and Shane Turgeon of TSRI
contributed to the study entitled, “RPM-1 Uses Both Ubiquitin Ligase and Phosphatase-Based
Mechanisms to Regulate DLK-1 during Neuronal Development.” For more information, see
http://www.plosgenetics.org/article/info%3Adoi%2F10.1371%2Fjournal.pgen.1004297
The first author of the study, “The Nesprin Family Member ANC-1 Regulates Synapse Formation
and Axon Termination by Functioning in a Pathway with RPM-1 and β-Catenin,” is Erik Tulgren of
the University of Minnesota. Other authors include Shane Turgeon and Karla Opperman of TSRI.
For more information, see http://www.plosgenetics.org/doi/pgen.1004481
The first author of the study, “RPM-1 Is Localized to Distinct Subcellular Compartments and
Regulates Axon Length in GABAergic Motor Neurons,” is Karla Opperman of TSRI. For more
information, see http://www.neuraldevelopment.com/content/9/1/10
The work was supported by the National Institutes of Health (grant R01 NS072129) and the National
Science Foundation (grant IOS- 1121095).
Scripps Florida Scientists Identify Gene that Plays a Surprising Role in Combating Aging
It is something of an eternal question: Can we slow or even reverse the aging process? Even though
genetic manipulations can, in fact, alter some cellular dynamics, little is known about the
mechanisms of the aging process in living organisms.
Now scientists from the Florida campus of The Scripps Research Institute (TSRI) have found in
animal models that a single gene plays a surprising role in aging that can be detected early on in
development, a discovery that could point toward the possibility of one day using therapeutics, even
some commonly used ones, to manipulate the aging process itself.
“We believe that a previously uncharacterized developmental gene known as Spns1 may mediate the
aging process,” said Shuji Kishi, a TSRI assistant professor who led the study, published recently by
the journal PLOS Genetics. “Even a partial loss of Spns1 function can speed aging.”
Using various genetic approaches to disturb Spns1 during the embryonic and/or larval stages of
zebrafish—which have emerged as a powerful system to study diseases associated with development
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and aging—the scientists were able to produce some models with a shortened life span, others that
lived long lives.
While most studies of “senescence”—declines in a cell's power of division and growth—have
focused on later stages of life, the study is intriguing in exploring this phenomenon in early stages.
“Mutations to Spns1 both disturbs developmental senescence and badly affects the long-term biochronological aging process,” Kishi said.
The new study shows that Spns1, in conjunction with another pair of tumor suppressor genes, beclin
1 and p53 can, influences developmental senescence through two differential mechanisms: the Spns1
defect was enhanced by Beclin 1 but suppressed by ‘basal’ p53. In addition to affecting senescence,
Spns1 impedes autophagy, the process whereby cells remove unwanted or destructive proteins and
balance energy needs during various life stages.
Building on their insights from the study, Kishi and his colleagues noted in the future therapeutics
might be able influence aging through Spns1. He noted one commonly used antacid, Prilosec, has
been shown to temporarily suppress autophagic abnormality and senescence observed in the Spns1
deficiency.
The first author of the study, “Aberrant Autolysosomal Regulation Is Linked to The Induction of
Embryonic Senescence: Differential Roles of Beclin 1 and p53 in Vertebrate Spns1 Deficiency,” is
Tomoyuki Sasaki of TSRI. Other authors include Shanshan Lian, Jie Qi, Sujay Guha, Jennifer L.
Johnson, Sergio D. Catz and Matthew Gill of TSRI; Peter E. Bayliss of the University Health
Network, Toronto, Canada; Christopher E. Carr of the Massachusetts Institute of Technology;
Patrick Kobler and Kailiang Jia of Florida Atlantic University; and Daniel J. Klionsky of the
University of Michigan. The paper can be accessed at
http://www.plosgenetics.org/article/info%3Adoi%2F10.1371%2Fjournal.pgen.1004409
The work was supported by The Ellison Medical Foundation, Glenn Foundation for Medical
Research, A-T Children's Project), the National Institutes of Health (NIH) National Institute of
Aging (AG022641) and the National Institute of General Medical Sciences (GM053396,
GM101508).
Scientists Find Ancient Protein-Building Enzymes Have Undergone Metamorphosis and
Evolved Diverse New Functions
The Previously Unrecognized Layer of Biology Could Offer New Drug Targets
Scientists at The Scripps Research Institute (TSRI) and Hong Kong University of Science and
Technology (HKUST) and their collaborators have found that ancient enzymes, known for their
fundamental role in translating genetic information into proteins, evolved myriad other functions in
humans. The surprising discovery highlights an intriguing oddity of protein evolution as well as a
potentially valuable new class of therapeutic proteins and therapeutic targets.
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“These new protein variants represent a previously unrecognized layer of biology—the ramifications
of this discovery are now unfolding,” said team leader Paul Schimmel, Ernest and Jean Hahn
Professor of Molecular Biology and Chemistry at TSRI (California and Florida) who also holds an
appointment at HKUST Jockey Club Institute for Advanced Study (IAS).
Mingjie Zhang, a co-author of the paper who is IAS Senior Fellow and Kerry Holdings Professor of
Science, Division of Life Science at HKUST, added, “This breakthrough finding not only uncovers a
vast area of new biology, but also provides opportunities to develop protein-based drugs for various
human diseases associated with malfunctions of these newly discovered proteins. The successful
collaboration among scientists from HKUST, TSRI and two biotech companies from the U.S. and
Hong Kong also serves as a wonderful example of the close connections between basic research and
biotechnology development.”
The findings appear in the July 18, 2014 issue of Science.
Greater Complexity
The discovery concerns aminoacyl tRNA synthetases (AARSs), a group of 20 enzymes whose most
basic function is to connect the nucleotide codes contained in genes to their corresponding protein
building-blocks, namely, the 20 amino acids. Because AARSs are essential for the translation of
genetic information into working proteins, they are found in all life forms on the planet.
Scientists have been finding evidence in recent years that AARS enzymes exist in greater complexity
in more evolutionarily advanced organisms. In essence, these enzymes have acquired new segments
or “domains.” Curiously, these domains have no apparent relevance to protein translation. While
largely absent in lower forms of life, these domains are added in a progressive and accretive way in
evolution, in the long ascent over billions of years to humans.
To investigate further, Schimmel collaborated with colleagues at TSRI in California and Florida,
HKUST (including at the IAS), the San Diego biotech company aTyr Pharma (which Schimmel cofounded), Stanford and the Hong Kong biotech company Pangu Biopharma (an aTyr subsidiary).
Using advanced, sensitive techniques, the team identified nearly 250 previously unknown genetranscript variants of AARS in different human cell types. These variants, known as splice variants,
are alternative assemblies of the discrete sequences of information (exons) contained in AARS
genes. Genes frequently contain multiple exons that can be spliced together in alternative ways—
thus in principle enabling a single active gene to encode multiple proteins with different functions.
But the new findings suggest that evolution has been unusually prolific at creating AARS splice
variants.
Potential New Class of Drug Targets
The team’s further investigations revealed that the new AARS variants often are produced only in
specific cell types such as brain or immune cells and/or appear only during certain stages of
development.
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Remarkably, most of the new splice variants lack entirely the standard “catalytic domain” that
supports protein translation—confirming that they are not directly involved in that fundamental
process. Initial screening of the biological activities of these variants hinted at a diversity of other
functions. One variant selected for analysis turned out to be a powerful driver for the proliferation of
muscle fiber cells in a laboratory dish.
Schimmel and his collaborators will now turn to more comprehensive studies of the new AARS
variants and their specific functions. “We believe that these proteins have relevance to multiple
human diseases,” he said. “They thus represent a very important class of new protein therapeutics
analogous to widely used injectable protein therapeutics such as growth hormone, insulin,
erythropoietin (EPO) (which regulates red blood cell production) and granulocyte colony-stimulating
factor (G-CSF) (which stimulates the bone marrow).”
The first author of the report, “Human tRNA synthetase catalytic nulls with diverse functions,” was
Wing-Sze Lo from the IAS-Scripps R&D Laboratory at HKUST and Pangu Biopharma. In addition
to Schimmel and Zhang, other authors included Zhiwen Xu, Ching-Fun Lau, Feng Wang and Jie
Zhou, also from the IAS-Scripps R&D Laboratory at HKUST and Pangu Biopharma; John D.
Mendlein, Leslie A. Nangle and Kyle P. Chiang of aTyr Pharma; Kin-Fai Au, formerly at Stanford
University and now at the University of Iowa; Wing Hung Wong of Stanford University; Min Guo
of TSRI’s Florida campus; and Elisabeth Gardiner and Xiang-Lei Yang from TSRI’s California
campus.
Funding for the research was provided by the Hong Kong Government’s Innovation and Technology
Fund (grants UIM181, UIM192 and UIM199), the National Foundation for Cancer Research, the
National Institutes of Health (grants R01CA92577, R01GM088278, R01NS085092, R01HG005717
and R01GM100136), aTyr Pharma and Pangu Biopharma.
Scripps Florida Scientists Find Genetic Mutations Linked to Salivary Gland Tumors
The Findings May Point the Way to New Cancer Treatments
Research conducted at the Florida campus of The Scripps Research Institute (TSRI) has discovered
links between a set of genes known to promote tumor growth and mucoepidermoid carcinoma, an
oral cancer that affects the salivary glands. The discovery could help physicians develop new
treatments that target the cancer’s underlying genetic causes.
The research, published recently online ahead of print by the Proceedings of the National Academy
of Sciences, shows that a pair of proteins joined together by a genetic mutation—known as
CRTC1/MAML2 (C1/M2)—work with MYC, a protein commonly associated with other cancers, to
promote the oral cancer’s growth and spread.
“This research provides new insights into the molecular mechanisms of these malignances and
points to a new direction for potential therapies,” says TSRI biologist Michael Conkright, Ph.D.,
who led the study.
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The C1/M2 protein is created when the genes encoding CRTC1 and MAML2 mutate into a single
gene through a process known as chromosomal translocation. Such mutant “chimera” genes are
linked to the formation of several forms of cancer. The team discovered that the C1/M2 protein
further activates genetic pathways regulated by MYC, in addition to CREB, to begin a series of
cellular changes leading to the development of mucoepidermoid carcinoma.
“The identification of unique interactions between C1/M2 and MYC suggests that drugs capable of
disrupting these interactions may have therapeutic potential in the treatment of mucoepidermoid
carcinomas,” said Antonio L. Amelio, Ph.D., first author of the study who is now assistant professor
with the UNC School of Dentistry and member of the UNC Lineberger Comprehensive Cancer
Center.
Researchers have known about the role of C1/M2 and its interactions with another protein, CREB, in
the development of mucoepidermoid carcinoma, and physicians screen patients for the presence of
the C1/M2 protein when testing for this cancer. These new findings deepen the understanding of
C1/M2’s role by revealing that it works with a family of cancer-associated genes known as the MYC
family to drive the cellular changes necessary for a tumor to develop.
The discovery of these new protein interactions may also reveal insights into the mechanisms behind
other cancers that arise due to other genetic mutations involving the CREB and MYC pathways.
In addition to Conkright and Amelio, other authors of the study, “CRTC1/MAML2 gain-of-function
interactions with MYC create a gene signature predictive of cancers with CREB–MYC
involvement,” include Mohammad Fallahi of IT Informatics, Franz X. Schaub, Mariam B. Lawani,
Adam S. Alperstein, Mark R. Southern, Brandon M. Young and John L. Cleveland of TSRI, and
Min Zhang, Lizi Wu, Maria Zajac-Kaye and Frederic J. Kaye of Shands Cancer Center, University
of Florida (Gainesville).
The research was supported in part by a Howard Temin Pathway to Independence Award in Cancer
Research from the National Cancer Institute (NCI) (K99-CA157954), National Institutes of
Health/NCI R01 Grant CA100603, a PGA National WCAD Cancer Research Fellowship and Ruth
L. Kirschstein National Research Service Award from the National Cancer Institute (F32CA134121), the Margaret Q. Landerberger Research Foundation, a Swiss National Foundation
Postdoctoral Fellowship and monies from the State of Florida to TSRI’s Scripps Florida.
A Gene Linked to Disease Found to Play a Critical Role in Normal Memory Development
It has been more than 20 years since scientists discovered that mutations in the gene huntingtin cause
the devastating progressive neurological condition Huntington’s disease, which involves involuntary
movements, emotional disturbance and cognitive impairment. Surprisingly little, however, has been
known about the gene’s role in normal brain activity.
Now, a study from The Scripps Research Institute’s (TSRI’s) Florida campus and Columbia
University shows it plays a critical role in long-term memory.
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“We found that huntingtin expression levels are necessary for what is known as long-term synaptic
plasticity—the ability of the synapses to grow and change—which is critical to the formation of
long-term memory,” said TSRI Assistant Professor Sathyanarayanan V. Puthanveettil, who led the
study with Nobel laureate Eric Kandel of Columbia University.
In the study, published recently by the journal PLOS ONE, the team identified an equivalent of the
human huntingtin protein in the marine snail Aplysia, a widely used animal model in genetic studies,
and found that, just like its human counterpart, the protein in Aplysia is widely expressed in neurons
throughout the central nervous system.
Using cellular models, the scientists studied what is known as the sensory-to-motor neuron synapse
of Aplysia—in this case, gill withdrawal, a defensive move that occurs when the animal is disturbed.
The study found that the expression of messenger RNAs of huntingtin—messenger RNAs are used
to produce proteins from instructions coded in genes—is increased by serotonin, a neurotransmitter
released during learning in Aplysia. After knocking down production of the huntingtin protein,
neurons failed to function normally.
“During the learning, production of the huntingtin mRNAs is increased both in pre- and postsynaptic neurons—that is a new finding,” Puthanveettil said. “And if you block production of the
protein either in pre- or post-synaptic neuron, you block formation of memory.”
The findings could have implications for the development of future treatments of Huntington’s
disease. While the full biological functions of the huntingtin protein are not yet fully understood, the
results caution against a therapeutic approach that attempts to eliminate the protein entirely.
The first author of the study, “Huntingtin Is Critical Both Pre- and Postsynaptically for Long-Term
Learning-Related Synaptic Plasticity in Aplysia,” is Yun-Beom Choi of Columbia University. Other
authors include Beena M. Kadakkuzha, Xin-An Liu and Komolitdin Akhmedov of TSRI. For more
information on the study, see
http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0103004
The work was supported by the Howard Hughes Medical Institute, the National Institutes of Health
(Grant NS053415), the Whitehall Foundation and the State of Florida.
Scripps Florida and Mayo Clinic Team Up to Successfully Target Common Mutation in Lou
Gehrig’s Disease and Frontotemporal Dementia
An international team led by scientists from the Florida campuses of The Scripps Research Institute
(TSRI) and the Mayo Clinic have for the first time successfully designed a therapeutic strategy
targeting a specific genetic mutation that causes a common form of amyotrophic lateral sclerosis
(ALS), better known as Lou Gehrig’s disease, as well a type of frontotemporal dementia (FTD).
The scientists developed small-molecule drug candidates and showed they interfere with the
synthesis of an abnormal protein that plays a key role in causing both diseases. The team also
developed biomarkers that can test the efficacy of this and other therapies.
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The study, led by Professor Matthew Disney of TSRI and Professor of Neuroscience Leonard
Petrucelli of the Mayo Clinic, was published online ahead of print August 14, 2014 in the journal
Neuron.
“Our small molecules target a genetic defect that is by far the most major cause of familial ALS, and
if you have this defect you are assured of getting ALS or FTD,” Disney said. “Our findings show for
the first time that targeting this mutation with a small-molecule drug candidate can inhibit toxic
protein translation—and establishes that it could be possible to treat a large number of these patients,
but this is just the start of these studies and additional investigations need to be done.”
Currently, ALS is usually fatal two to five years after diagnosis, and there is no effective treatment
for FTD, a neurodegenerative disease that destroys neurons in the frontal lobes of the brain.
Toxic Buildup
The mutation that can cause both diseases affects a gene known as C90RF72 and involves a repeat
expansion, a longer than usual repetitive genetic sequence. This results in abnormal strands of RNA
and the production of toxic “c9RAN proteins.”
Disney and his Scripps Florida colleagues initially designed three small-molecule drug candidates
that decreased RNA translation or production of these toxic proteins in cell culture. The Mayo team
developed the patient-derived cell models in which to test the compounds and the biomarker to
assess compound activity. Both teams then worked together to show that the lead agent’s mode of
action was targeting the toxic RNA, binding to and blocking the toxic RNA’s ability to interact with
other key proteins.
Two of the compounds significantly decreased levels of the toxic protein. Using a series of
increasing dosages of the drug candidates, the scientists found that the highest dosage of one reduced
the toxic protein by nearly 50 percent.
The scientists also discovered that c9RAN proteins produced by the abnormal RNA can be measured
in the spinal fluid of ALS patients. They are now evaluating whether these proteins are also present
in spinal fluid of patients diagnosed with FTD.
“A decrease in the levels of toxic proteins in cerebrospinal fluid in response to treatment would
demonstrate the drug is working,” Petrucelli said. “While additional studies must be done, this
finding suggests that these proteins may provide a direct means to measure a patient’s response to
experimental drugs that target abnormal RNA.”
Toxic proteins found in spinal fluid could also become an enrollment tool in human clinical trials,
added Disney, who was enthusiastic about the collaboration with the Mayo Clinic and the larger
team. “Our collective biological and chemical expertise made this research possible,” he said. “This
is just the beginning of what we can do together.”
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The first authors of the study, “Discovery of a Biomarker and Lead Small Molecules to Target
r(GGGGCC)-Associated Defects in c9FTD/ALS,” are Zhaoming Su of TSRI and Yongjie Zhang,
Tania F. Gendron and Peter O. Bauer of the Mayo Clinic.
Other authors include Wang-Yong Yang and Erik Fostvedt of TSRI; Jeannie Chew, Karen JansenWest, Veronique V. Belzil, Pamela Desaro, Amelia Johnston, Karen Overstreet, Bradley F. Boeve,
Dennis Dickson, Rosa Rademakers and Kevin B. Boylan of the Mayo Clinic; Mary Kay Floeter of
the National Institute of Neurological Disorders and Stroke; Bryan J. Traynor of the National
Institute on Aging; Claudia Morelli of the IRCCS Instituto Auxologico Italiano, Milan, Italy;
Antonia Ratti and Vincenzo Silani of the IRCCS Instituto Auxologico Italiano, Milan, Italy and the
Universita degli Studi di Milano, Milan, Italy; and Robert H. Brown and Jeffrey D. Rothstein of
Johns Hopkins University.
The work was supported the National Institute on Aging of the National Institutes of Health (grants
R01GM097455, R01AG026251 and P50AG016574); National Institute of Neurological Disorders
and Stroke (grants R21NS074121, R21NS079807, R21NS084528, R01NS088689, R01NS063964,
R01NS077402 and R01NS050557); the American Recovery and Reinvestment Act of 2009 (awards
RC2-NS070-342 and P01NS084974); National Institute of Environmental Health Services (grant
R01ES20395); Department of Defense (ALSRP AL130125); Mayo Clinic Foundation; Mayo Clinic
Center for Regenerative Medicine; Mayo Clinic Center for Individualized Medicine; ALS
Association; Alzheimer's Association; Robert Packard Center for ALS Research at Johns Hopkins;
Target ALS; Project ALS; Angel Fund; the Italian Ministry of Health (RF-2009-1473856) and the
European Commission.
Scripps Florida Scientists Make Diseased Cells Synthesize Their Own Drug
In a new study that could ultimately lead to many new medicines, scientists from the Florida campus
of The Scripps Research Institute (TSRI) have adapted a chemical approach to turn diseased cells
into unique manufacturing sites for molecules that can treat a form of muscular dystrophy.
“We’re using a cell as a reaction vessel and a disease-causing defect as a catalyst to synthesize a
treatment in a diseased cell,” said TSRI Professor Matthew Disney. “Because the treatment is
synthesized only in diseased cells, the compounds could provide highly specific therapeutics that
only act when a disease is present. This means we can potentially treat a host of conditions in a very
selective and precise manner in totally unprecedented ways.”
The promising research was published recently in the international chemistry journal Angewandte
Chemie.
Targeting RNA Repeats
In general, small, low molecular weight compounds can pass the blood-brain barrier, while larger,
higher weight compounds tend to be more potent. In the new study, however, small molecules
became powerful inhibitors when they bound to targets in cells expressing an RNA defect, such as
those found in myotonic dystrophy.
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Myotonic dystrophy type 2, a relatively mild and uncommon form of the progressive muscle
weakening disease, is caused by a type of RNA defect known as a “tetranucleotide repeat,” in which
a series of four nucleotides is repeated more times than normal in an individual’s genetic code. In
this case, a cytosine-cytosine-uracil-guanine (CCUG) repeat binds to the protein MBNL1, rendering
it inactive and resulting in RNA splicing abnormalities that, in turn, results in the disease.
In the study, a pair of small molecule “modules” the scientists developed binds to adjacent parts of
the defect in a living cell, bringing these groups close together. Under these conditions, the adjacent
parts reach out to one another and, as Disney describes it, permanently hold hands. Once that
connection is made, the small molecule binds tightly to the defect, potently reversing disease defects
on a molecular level.
“When these compounds assemble in the cell, they are 1,000 times more potent than the small
molecule itself and 100 times more potent than our most active lead compound,” said Research
Associate Suzanne Rzuczek, the first author of the study. “This is the first time this has been
validated in live cells.”
Click Chemistry Construction
The basic process used by Disney and his colleagues is known as “click chemistry”—a process
invented by Nobel laureate K. Barry Sharpless, a chemist at TSRI, to quickly produce substances by
attaching small units or modules together in much the same way this occurs naturally.
“In my opinion, this is one unique and a nearly ideal application of the process Sharpless and his
colleagues first developed,” Disney said.
Given the predictability of the process and the nearly endless combinations, translating such an
approach to cellular systems could be enormously productive, Disney said. RNAs make ideal targets
because they are modular, just like the compounds for which they provide a molecular template.
Not only that, he added, but many similar RNAs cause a host of incurable diseases such as ALS
(Lou Gehrig’s Disease), Huntington’s disease and more than 20 others for which there are no known
cures, making this approach a potential route to develop lead therapeutics to this large class of
debilitating diseases.
In addition to Rzuczek and Disney, the other author of the study, “A Toxic RNA Catalyzes the In
Cellulo Synthesis of Its Own Inhibitor,” is HaJeung Park of TSRI. For more information on the
study, see http://onlinelibrary.wiley.com/doi/10.1002/anie.201406465/abstract
The work was supported by the Muscular Dystrophy Foundation, the Myotonic Dystrophy
Foundation and the State of Florida.
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Team Identifies Important Regulators of Immune Cell Response
In a collaborative study, scientists from the Florida campus of The Scripps Research Institute (TSRI)
and the La Jolla Institute for Allergy and Immunology have developed a more effective method to
determine how immune cells called T cells differentiate into specialized types of cells that help
eradicate infected cells and assist other immune cells during infection.
The new approach, published recently by the journal Immunity, could help accelerate laboratory
research and the development of potential therapeutics, including vaccines. The method may also be
used to identify the genes that underlie tumor cell development.
There are approximately 40,000 genes in each of our cells, but functions for only about half of them
are known. The classical approach to determine the function of individual genes is slow.
“Typically, studies to identify differentiation players are done one gene at a time,” said Associate
Professor Matthew Pipkin of TSRI, who led the study with Professor Shane Crotty of the La Jolla
Institute for Allergy and Immunology. “Our study describes a novel method that can ‘screen’ entire
gene families to discover the functions of a large number of individual genes simultaneously, a far
more efficient methodology.”
In the new study, the team examined genes that regulate the specialization of T cells into “effector”
cells that eliminate pathogens during infection and “memory” cells that survive long-term to
maintain guard after the first infection has been cleared, keeping the same pathogens from reinfecting the body after it has fought them off once.
In their experiments, Pipkin, Crotty and their colleagues created a mixture of T cells, identical except
that the expression of a different gene was interrupted in each cell so the pool of cells represented
disruption of a large set of genes. The researchers then assessed the cells’ response to lymphocytic
choriomeningitis virus (LCMV). Before-and-after-infection studies revealed which cells with
interrupted genes had emerged after infection; cells in which disruption of a particular gene resulted
in it being lost from the mixture indicated the gene played a role in promoting the cell’s development
into an antiviral T cell.
The study successfully identified two previously unknown factors that work together during T cell
differentiation—Cyclin T1 and its catalytic partner Cdk9, which together form the transcription
elongation factor (P-TEFb). While widely expressed throughout the body and used in a number of
developmental processes, the factors were previously unknown to be important in the differentiation
of both antiviral CD4 and CD8 T cells.
“One of the regulators we uncovered normally enhances effector T cell differentiation at the expense
of generating memory T cells and T cells that orchestrate antibody production,” Pipkin said. “That’s
one candidate that you’d want to ‘turn down’ if you wanted to create more T cells that form memory
cells and promote a more effective antibody response—something that would be extremely helpful
in developing a vaccine.”
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The first authors of the study, “In Vivo RNA Interference Screens Identify Regulators of Antiviral
CD4+ and CD8+ T Cell Differentiation,” are Runqiang Chen and Simon Bélanger of the La Jolla
Institute for Allergy and Immunology. Other authors include Megan A. Frederick of TSRI; and Bin
Li, Robert J. Johnston, Nengming Xiao, Yun-Cai Liu, Sonia Sharma, Bjoern Peters and Anjana Rao
of the La Jolla Institute for Allergy and Immunology. See
http://www.cell.com/immunity/abstract/S1074-7613(14)00272-6
This work was supported by the National Institutes of Health (RC4 AI092763, R01 AI095634, R01
CA42471, R01 072543 and U19 AI109976) and Frenchman’s Creek Women for Cancer Research.
New Clinical Trial Data: Scripps Research Institute MS Drug Candidate Also Shows Promise
for Ulcerative Colitis
Positive new clinical data were released recently on a drug candidate for ulcerative colitis that was
first discovered and synthesized at The Scripps Research Institute (TSRI).
According to recent results from a Phase 2 study of 199 patients with active, moderate to severe
disease, the drug candidate RPC1063 has potential to significantly improve the treatment paradigm
for ulcerative colitis patients. The latest results show that, after eight weeks of treatment with a 1 mg
dose of RPC1063, 16.4 percent of patents were in clinical remission, as compared to 6.2 percent of
patients on placebo.
“We are delighted that RPC1063 is showing promise for ulcerative colitis patients in addition to its
already significant efficacy and safety data in multiple sclerosis,” said TSRI Professor Hugh Rosen,
who together with Professor Ed Roberts led the team that discovered RPC-1063. “Research carried
out at TSRI since 2002 has led to the discovery of fundamental mechanisms that can be modulated
for potential treatments of a variety of autoimmune diseases including ulcerative colitis and multiple
sclerosis, and the unique multidisciplinary environment in chemistry and biology at TSRI allowed
this progression to clinical trials.”
The clinical trial, sponsored by Receptos, Inc., the San Diego biotechnology company now
developing the drug, also showed that RPC1063 was generally well tolerated.
Ulcerative colitis is a chronic condition that involves inflammation and sores in the inner lining of
the digestive tract. Ulcerative colitis is an inflammatory bowel disease, which, along with Crohn’s
disease, affects more than one million people nationwide, according to the U.S. Centers for Disease
Control and Prevention. Some people have mild disease, while others are affected with lifethreatening complications.
While existing medications for ulcerative colitis do help some patients, 23 to 45 percent of ulcerative
colitis sufferers progress and eventually require surgical removal of all or part of the colon,
according to the Crohn’s and Colitis Foundation of America.
The drug candidate RPC1063 was derived from a screening “hit” from the National Institutes of
Health molecular library at Scripps Florida’s Molecular Screening Center, using assay technology
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from the Rosen lab in La Jolla. The Roberts and Rosen labs then developed significant medicinal
chemistry to turn that hit into a validated lead, and then ultimately a drug candidate.
TSRI then licensed the compound to Receptos, which is developing RPC1063 for approval by the
U.S. Food and Drug Administration.
The latest results come from Receptos’s multi-national, multi-center, double-blind, randomized,
placebo-controlled study investigating the effect of two active doses of RPC1063 versus placebo for
the treatment of moderately to severely active ulcerative colitis. For more information on the results,
see the press release from Receptos at http://ir.receptos.com/releasedetail.cfm?ReleaseID=878411
In light of the current positive results, Receptos plans to initiate a Phase 3 trial of RPC1063 for
ulcerative colitis, as well as a Phase 2 study of the drug candidate for Crohn’s disease.
The mechanism of RPC1063 (Sphingosine 1-Phosphate Receptor modulation) may also be
significant in the treatment of other autoimmune diseases. Receptos is also currently evaluating the
drug candidate in a Phase 3 study for the treatment of multiple sclerosis.
Scripps Florida Scientists Uncover Major Factor in Development of Huntington’s Disease
Scientists from the Florida campus of The Scripps Research Institute (TSRI) have uncovered a major
contributor to Huntington’s disease, a devastating progressive neurological condition that produces
involuntary movements, emotional disturbance and cognitive impairment.
Using an animal model of Huntington’s disease, the new study shows that signaling by a specific
protein can trigger onset of the disease and lead to exacerbation of symptoms. These findings,
published in the October 28, 2014 issue of the journal Science Signaling, offer a novel target for
drug development.
It has been more than 20 years since scientists discovered that mutations in the gene huntingtin cause
Huntington’s disease; the product of the gene, Huntingtin protein, is widely expressed is almost all
of the cells in the body.
The disease results in an early loss of neurons in the striatum, part of the forebrain that is responsible
for coordinating thought with movement—when you want to move your arm, the striatum lets your
muscles know. Unfortunately, the precise physiological role for huntingtin in disease onset and
progression remains unclear.
The new study, however, shows for the first time a functional connection between huntingtin and
mTOR, a developmentally important gene that integrates signals from multiple pathways, such as
growth factors and hormones, to regulate a variety of critical cell functions. Specifically, the
scientists found that the huntingtin protein activates signaling by a protein complex known as
mTORC1 (mechanistic-target of rapamycin kinase (mTOR) complex 1). Depleting huntingtin
reduces mTORC1 activity; an overexpression of huntingtin increases it.
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“In our previous work, we showed that there is a protein in the striatum that interacts with huntingtin
and makes it more toxic—this protein can activate mTORC1,” said Srinivasa Subramaniam, a TSRI
biologist who led the study. “What we didn’t know was how TORC1 and huntingtin were related.
What we found for the first time in this new study is that huntingtin can activate mTORC1 and
increase its activity in the striatum of mice—thus prematurely initiating the disease.”
In the new research, Subramaniam and his colleagues selectively deleted a gene that inhibits
mTORC1 activity in the animal model striatum, which caused a relatively rapid increase in the
severity of behavioral abnormalities related to Huntington’s disease, as well as premature death.
“This indicates for the first time that huntingtin is a novel regulator of mTORC1 activity that
contributes to the pathogenesis of the disease, at least in animal models,” he said.
The researchers will continue to investigate the role of mTORC1 in Huntington’s and other agedependent neurodegenerative diseases.
“We think that huntingtin may regulate mTORC1 both in the brain and in other tissue,” said William
Pryor, the first author of the study and a member of Subramaniam’s laboratory. “Our suspicion is
that this exacerbation of mTORC1 might compromise autophagy—the pathway that recycles
proteins and organelles—which has been implicated in neurodegeneration.”
“Reducing mTORC1 activation either through drugs or low-protein foods may have a positive
influence on preventing the disease process,” said Subramaniam.
In addition to Subramaniam and Pryor, other authors of the study, “Huntingtin Regulates mTORC1
Pathway that Exacerbates Huntington Disease Pathogenesis,” include Neelam Shahani, Supriya
Swarnkar, Wen-Chin Huang and Damon T. Page of TSRI; and Marta Biagioli and Marcy E.
MacDonald of the Center for Human Genetic Research, Massachusetts General Hospital.
The study was supported by the state of Florida and the O'Keeffe Neuroscience Scholar Award.
Scripps Florida Scientists Unveil New Targets and Test to Develop Treatments for Memory
Disorders
In a pair of related studies, scientists from the Florida campus of The Scripps Research Institute
(TSRI) have identified a number of new therapeutic targets for memory disorders and have
developed a new screening test to uncover compounds that may one day work against those
disorders.
The two studies, one published in the journal Proceedings of the National Academy of Sciences
(PNAS), the other in the journal ASSAY and Drug Development Technologies, could lead new
approaches to some of the most problematic diseases facing a rapidly aging world population,
including Alzheimer’s and Huntington’s diseases and dementia.
“We are actively looking at molecules critical to memory formation, so these two studies work in
parallel,” said Sathyanarayanan V. Puthanveettil, a TSRI biologist who led both studies. “In one
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study, we’re reaching for a basic understanding of the process, and in the other, we’re finding new
ways to identify drug candidates so that we can cure these diseases.”
Unlocking the ‘Synaptic Proteome’
The PNAS study is one of the first detailed descriptions of the proteins that are transported to the
synapses, which as a group are called the “synaptic proteome.” Synapses are the part of a nerve cell
(neuron) that passes electrochemical signals to other cells during functions such as memory storage.
This new approach has the potential to advance our understanding of how synapses work, how their
composition changes with learning and how brain diseases might affect them.
“We know these molecules function in the synapse, and if we can regulate their function there may
be some very good therapeutic opportunities there,” Puthanveettil said.
The study focuses on kinesin, a molecular motor protein that plays a role in the transport of other
proteins throughout a cell.
Analyzing three kinesin complexes, the researchers found that approximately 40 to 50 percent of the
protein cargos were synaptic proteins—and that the identity and location of these kinesins determine
which proteins they transport. These results reveal a previously underappreciated role of kinesins in
regulating the composition of the entire synaptic proteome.
Interestingly, a bioinformatics analysis revealed the three kinesin cargo complexes examined in the
study are involved in neurologic diseases. Approximately 60 cargos (out of 155) of the kinesin
Kif5C are implicated in psychiatric disorders, while around 20 cargos of another kinesin Kif3A are
implicated in developmental disorders.
“This shows for the first time how kinesins expressed in the same neurons can carry substantially
different cargos,” said Research Associate Xin-An Liu, the first author of the study. “We can use this
approach to identify what molecules may be targeted for memory and in major disorders. The next
step is to find how the synaptic proteome changes in neuropsychiatric diseases.”
Toward New Drug Candidates
In the ASSAY study, Puthanveettil and his colleagues describe their new high-throughput screening
test for discovering potential drug candidates based on kinesin and axonal transport for the treatment
of memory disorders.
“The luminescence-based assay that we developed is highly reproducible and robust,” said
Puthanveetil.
Using the approach, the team screened a compound collection and identified a number of small
molecules that turned on or off activity of a human kinesin.
In addition to Liu and Puthanveettil, other authors of the PNAS study, “New Approach to Capture
and Characterize Synaptic Proteome,” include Beena Kadakkuzha, Bruce Pascal, Caitlin Steckler,
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Komolitdin Akhmedov and Michael Chalmers of The Scripps Research Institute; and Long Yan of
Max Planck Florida Institute for Neuroscience. See
http://www.pnas.org/content/early/2014/10/28/1401483111.abstract
This study was supported by the Whitehall Foundation and the National Institute of Mental Health of
the National Institutes of Health (R21MH096258-01A1).
In addition to Puthanveettil and Kadakkuzha, authors of the ASSAY study, “High-Throughput
Screening for Small Molecule Modulators of Motor Protein Kinesin,” include Timothy Spicer, Peter
Chase, Jeffery B. Richman and Peter Hodder (present address: Amgen, Inc.) of TSRI. See
http://online.liebertpub.com/doi/abs/10.1089/adt.2014.579
This work was supported by the Alzheimer’s Drug Discovery Foundation, Margaret Q.
Landenberger Research Foundation and TSRI.
Scripps Florida Scientists Determine Structure of a Molecular Complex Critical for Joining
Cells Together
Scientists from the Florida campus of The Scripps Research Institute (TSRI) have for the first time
determined the structure of a large molecular complex that plays a vital role in cell adhesion, the
force that binds cells together in all animals, including humans—without it, there would be a
tendency for them to simply fall apart.
The new study, led by Scripps Florida Associate Professor T. Izard, was published December 8,
2014, and highlighted in an “In this Issue” article by the Journal of Cell Biology.
This critical cell binding is done through specialized cell surface adhesion complexes called
adherens junctions (which direct the formation of tight, Velcro-like contacts among cells), other
structural proteins called F-actin (the “F” stands for filament) and focal adhesion complexes. This
process is necessary for cell migration and morphogenesis, the shaping of tissues and organs that is
an important part of development.
In the study, the scientists produced an x-ray crystallography image of the cytoskeleton protein
vinculin, an essential regulator of adherens junctions and focal adhesion, binding with a fat or lipid
known as PIP2, a major component of all cell membranes. The images revealed that PIP2 binding
alters vinculin structure to direct oligomerization—the linking together of a few protein or nucleic
acid macromolecules—which, in turn, stabilizes focal adhesion complexes.
The structural findings also revealed that vinculin’s PIP2 and actin-binding sites are distinct,
suggesting that the protein may be able to bind to both molecules simultaneously.
In additional experiments, the scientists determined that PIP2 binding is necessary for maintaining
optimal vinculin dynamics, turnover in F-actin and for cell migration and spreading.
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The structure and functions of other lipid-and-actin-binding cytoskeleton proteins may have similar
mechanisms of action for PIP2, according to the authors.
In addition to Izard, authors of the study, “Lipid Binding Promotes Oligomerization and Focal
Adhesion Activity of Vinculin,” were Krishna Chinthalapudi, Erumbi S. Rangarajan and Dipak N.
Patil of TSRI; and Eric M. George and David T. Brown of the University of Mississippi. For more
information, see http://jcb.rupress.org/content/207/5/643
The work is supported by grants from the National Institute of General Medical Sciences, the
National Institutes of Health; the US Department of Defense; and by the State of Florida.
Scripps Research Institute Scientists Uncover New, Fundamental Mechanism for How
Resveratrol Provides Health Benefits
The Ingredient Found in Red Wine Activates Ancient Stress Response
Scientists at The Scripps Research Institute (TSRI) have found that resveratrol, the red-wine
ingredient once touted as an elixir of youth, powerfully activates an evolutionarily ancient stress
response in human cells. The finding should dispel much of the mystery and controversy about how
resveratrol really works.
“This stress response represents a layer of biology that has been largely overlooked, and resveratrol
turns out to activate it at much lower concentrations than those used in prior studies,” said senior
investigator Paul Schimmel, professor and member of the Skaggs Institute for Chemical Biology at
TSRI.
“With these findings we have a new, fundamental mechanism for the known beneficial effects of
resveratrol,” said lead author Mathew Sajish, a senior research associate in the Schimmel laboratory.
The discovery is reported in the advance online edition of Nature on December 22.
Resveratrol is a compound produced in grapes, cacao beans, Japanese knotweed and some other
plants in response to stresses including infection, drought and ultraviolet radiation. It has attracted
widespread scientific and popular interest over the past decade, as researchers have reported that it
extended lifespan and prevented diabetes in obese mice and vastly increased the stamina of ordinary
mice running on wheels.
More recently, though, scientists in this field have disagreed about the signaling pathways
resveratrol activates to promote health, calling into question some of resveratrol’s supposed health
benefits—particularly given the unrealistically high doses used in some experiments.
Outsiders to the Controversy
Schimmel and Sajish came to this controversy as outsiders. Schimmel’s laboratory is known for its
work not on resveratrol but on an ancient family of enzymes, the tRNA synthetases. The primary and
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essential function of these enzymes is to help translate genetic material into the amino-acid building
blocks that make proteins. But as Schimmel and others have shown since the late 1990s, tRNA
synthetases have acquired an extensive set of added functions in mammals.
Earlier Xiang-Lei Yang, a TSRI professor in the Departments of Chemical Physiology and Cell and
Molecular Biology and former member of Schimmel’s laboratory, began to find hints that a tRNA
synthetase called TyrRS, which links the amino acid tyrosine to the genetic material that codes for it,
can move to the cell nucleus under stressful conditions—apparently taking on a protective, stressresponse role. Sajish noted that resveratrol appeared to have broadly similar stress-response
properties and also resembled TyrRS’s normal binding partner tyrosine. “I began to see TyrRS as a
potential target of resveratrol,” he said.
For the new study, Sajish and Schimmel put TyrRS and resveratrol together and showed with tests
including X-ray crystallography that resveratrol does indeed mimic tyrosine, well enough to fit
tightly into TyrRS’s tyrosine binding pocket. That binding to resveratrol, the team found, takes
TyrRS away from its protein translation role and steers it to a function in the cell nucleus.
Tracking the resveratrol-bound TyrRS in the nucleus, the researchers determined that it grabs and
activates the protein, PARP-1, a major stress response and DNA-repair factor thought to have a
significance influence on lifespan. The scientists confirmed the interaction in mice injected with
resveratrol. TyrRS’s activation of PARP-1 led, in turn, to the activation of a host of protective genes
including the tumor-suppressor gene p53 and the longevity genes FOXO3A and SIRT6.
Compatible with Red Wine
The first studies of resveratrol in the early 2000s had suggested that it exerts some of its positive
effects on health by activating SIRT1, also thought to be a longevity gene. But SIRT1’s role in
mediating resveratrol’s reported health-boosting effects has been questioned lately in terms of its
particular role.
The team’s experiments showed, however, that the TyrRS-PARP-1 pathway can be measurably
activated by much lower doses of resveratrol—as much as 1,000 times lower—than were used in
some of the more celebrated prior studies, including those focused on SIRT1. “Based on these
results, it is conceivable that moderate consumption of a couple glasses of red wine (rich in
resveratrol) would give a person enough resveratrol to evoke a protective effect via this pathway,”
Sajish said. He also suspects that effects of resveratrol that only appear at unrealistically high doses
may have confounded some prior findings.
Why would resveratrol, a protein produced in plants, be so potent and specific in activating a major
stress response pathway in human cells? Probably because it does much the same in plant cells, and
probably again via TyrRS—a protein so fundamental to life, due to its linkage to an amino acid, that
it hasn’t changed much in the hundreds of millions of years since plants and animals went their
separate evolutionary ways. “We believe that TyrRS has evolved to act as a top-level switch or
activator of a fundamental cell-protecting mechanism that works in virtually all forms of life,” said
Sajish.
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Whatever activity resveratrol naturally has in mammals may be an example of hormesis: the mild,
health-promoting activation of a natural stress response. “If resveratrol brought significant benefits
to mammals, they might have evolved a symbiotic relationship with resveratrol-producing plants,”
Sajish said.
“We think this is just the tip of the iceberg,” said Schimmel. “We think there are a lot more aminoacid mimics out there that can have beneficial effects like this in people. And we’re working on that
now.”
Schimmel and his laboratory also are searching for molecules that can activate the TyrRS stress
response pathway even more potently than resveratrol does.
The National Cancer Institute (CA92577), the National Foundation for Cancer Research and aTyr
Pharma, Inc. provided funding for the study, “A human tRNA synthetase is a potent PARP1activating effector target for resveratrol.” For more information, see http://www.nature.com
Scripps Florida Scientists Develop Novel Platform for Treatment of Breast, Pancreatic Cancer
Scientists from the Florida campus of The Scripps Research Institute (TSRI) have identified a novel
synthetic compound that sharply inhibits the activity of a protein that plays an important role in in
the progression of breast and pancreatic cancers.
In the new study, to be published in the February 2015 print edition of the journal Molecular
Pharmacology, the scientists showed that the compound, known as SR1848, reduces the activity and
expression of the cancer-related protein called “liver receptor homolog-1” or LRH-1.
“Our study shows that SR1848 removes LRH1 from DNA, shutting down expression of LRH-1
target genes, and halts cell proliferation,” said Patrick Griffin, chair of the TSRI Department of
Molecular Therapeutics and director of the Translational Research Institute at Scripps Florida. “It’s a
compound that appears to be a promising chemical scaffold for fighting tumors that are nonresponsive to standard therapies.”
LRH1 plays a crucial role in breast cancer through its regulation of genes involved in hormone
synthesis and cholesterol metabolism—also key risk factors in cardiovascular disease. LRH-1 has
also been implicated as a tumor promoter in intestinal and pancreatic cancer. Overexpression of
LRH-1 has been shown to promote invasiveness and metastasis, the usually lethal spread of the
disease.
“LRH-1 has been implicated in the proliferation and metastasis of estrogen receptor-positive breast
cancers and the more difficult to treat estrogen receptor-negative breast cancers,” said Research
Associate Alex Corzo, the first author of the study. “This suggests that repressing LRH-1 could be
useful in treating the more aggressive triple-negative breast cancer subtype where therapies are
currently so limited.”
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In fact, the study showed that levels of LHR-1 in a cell’s nucleus began to diminish four hours after
treatment with SR1848, and the compound repressed specific target genes as early as two hours after
administration.
Griffin noted that SR1848 also appears attractive as a potential therapeutic because of its lack of
impact on cells that do not express LRH1, which could mean few potential side effects.
“It’s a novel mechanism that needs more study,” he said.
In addition to Griffin and Corzo, other authors of the study, “Antiproliferation Activity of a Small
Molecule Repressor of Liver Receptor Homolog 1s,” are Yelenis Mari, Mi Ra Chang, Tanya Khan,
Dana Kuruvilla, Philippe Nuhant, Naresh Kumar, Graham M. West, Derek R. Duckett and William
R. Roush of TSRI. See http://molpharm.aspetjournals.org/content/87/2/296.full
This work was supported by the Intramural Research Program of the National Institutes of Health’s
(NIH) National Institute of Mental Health (U54-MH074404) and National Cancer Institute (R01CA134873).
Scripps Florida Scientists Move Closer to a Personalized Treatment Solution for Intellectual
Disability
Scientists from the Florida campus of The Scripps Research Institute (TSRI) have produced an
approach that protects animal models against a type of genetic disruption that causes intellectual
disability, including serious memory impairments and altered anxiety levels.
The findings, which focus on treating the effects of mutations to a gene known as Syngap1, have
been published online ahead of print by the journal Biological Psychiatry.
“Our hope is that these studies will eventually lead to a therapy specifically designed for patients
with psychiatric disorders caused by damagingSyngap1 mutations,” said Gavin Rumbaugh, a TSRI
associate professor who led the study. “Our model shows that the early developmental period is the
critical time to treat this type of genetic disorder.”
Damaging mutations in Syngap1 that reduce the number of functional proteins are one of the most
common causes of sporadic intellectual disability and are associated with schizophrenia and autism
spectrum disorder. Early estimates suggest that these non-inherited genetic mutations account for
two to eight percent of these intellectual disability cases. Sporadic intellectual disability affects
approximately one percent of the worldwide population, suggesting that tens of thousands of
individuals with intellectual disability may carry damaging Syngap1 mutations without knowing it.
In the new study, the researchers examined the effect of damaging Syngap1 mutations during
development and found that the mutations disrupt a critical period of neuronal growth—a period
between the first and third postnatal weeks in mouse models. “We found that a certain type of
cortical neuron grows too quickly in early development, which then leads to the premature formation
of certain types of neural circuits,” said Research Associate Massimilano Aceti, first author of the
study.
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The researchers reasoned that this process might cause permanent errors in brain connectivity and
that they might be able to head off these effects by enhancing the Syngap1 protein in the newborn
mutant mice. Indeed, they found that a subset of neurons were misconnected in the adult mutant
mice, suggesting that early growth of neurons can lead to life-long neural circuit connectivity
problems. Then, using advanced genetic techniques to raise Syngap1 protein levels in newborn
mutant mice, the researchers found this strategy completely protected the mice only when the
approach was started before this critical developmental window opened.
As a result of these studies, Rumbaugh and his colleagues are now developing a drug-screening
program to look for drug-like compounds that could restore levels of Syngap1 protein in defective
neurons. They hope that, as personalized medicine advances, such a therapy could ultimately be
tailored to patients based on their genotype.
In addition to Rumbaugh and Aceti, other authors of the study, “Syngap1 Haploinsufficiency
Damages a Postnatal Critical Period of Pyramidal Cell Structural Maturation Linked to Cortical
Circuit Assembly,” include Thomas K. Creson, Thomas Vaissiere, Camilo Rojas, Wen-Chin Huang,
Ya-Xian Wang, Ronald S. Petralia, Damon T. Page and Courtney A. Miller of TSRI. For more
information, see http://www.biologicalpsychiatryjournal.com/article/S0006-3223%2814%29005939/abstract
This work was supported by the National Institutes of Health’s National Institute for Neurological
Disorders and Stroke (R01NS064079), National Institute for Mental Health (R01MH096847),
National Institute for Drug Abuse (R01 DA034116; R03 DA033499) and National Institute on
Deafness and Other Communication Disorders/National Institutes of Health Intramural Research
Program; Mrs. Nancy Lurie; and the State of Florida.
Scripps Florida Scientists Establish that Drug Candidates Can Block Pathway Associated with
Cell Death in Parkinson’s Disease
In a pair of related studies, scientists from the Florida campus of The Scripps Research Institute
(TSRI) have shown their drug candidates can target biological pathways involved in the destruction
of brain cells in Parkinson's disease.
The studies, published in the Journal of Medicinal Chemistry and Scientific Reports, suggest that it
is possible to design highly effective and highly selective (targeted) drug candidates that can protect
the function of mitochondria, which provide the cell with energy, ultimately preventing brain cell
death.
These drug candidates act on what are known as the JNK (pronounced “junk”) kinases—JNK1,
JNK2 and JNK3—each an enzyme with a unique biological function. JNK is linked to many of the
hallmark components of Parkinson's disease, such as oxidative stress and programmed cell death.
“These are the first isoform selective JNK 2/3 inhibitors that can penetrate the brain and the first
shown to be active in functional cell-based tests that measure mitochondrial dysfunction,” said Philip
LoGrasso, a TSRI professor who led both studies. “In terms of their potential use as therapeutics,
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they’ve been optimized in every way but one—their oral bioavailability. That’s what we’re working
on now.”
The new studies raise the hope that such a therapy could prevent the gradual degeneration of brain
cells in Parkinson's disease and halt these patients’ decline.
“Some of these compounds had a level of selectivity that ranged as high as 20,000-fold against
competing targets and were extremely effective against oxidative stress and mitochondrial
dysfunction—both potent cell killers,” added HaJeung Park, director of Scripps Florida’s X-ray
Crystallography Core Facility and the first author of the Scientific Reports study.
The scientists found that within JNK3, a single amino acid—L144—was primarily responsible for
the high level of JNK3 selectivity. Isoform selectivity can help to limit potential side effects of a
drug.
Intriguingly, some recent studies have shown that JNK3 not only plays a central role in brain cell
death in Parkinson’s disease, but also in Alzheimer’s disease. LoGrasso and his colleagues also
believe their JNK3 drug candidates have potential for treating ALS (Lou Gehrig’s disease).
In addition to LoGrasso and Park, authors of the Scientific Reports study, “Structural Basis and
Biological Consequences for JNK2/3 Isoform Selective Aminopyrazoles,” include Sarah Iqbal,
Pamela Hernandez, Rudy Mora, Ke Zheng and Yangbo Feng of TSRI. See
http://www.nature.com/srep/index.html
The first author of the Journal of Medicinal Chemistry study, “Design and Synthesis of Highly
Potent and Isoform Selective JNK32 Inhibitors: SAR Studies on Aminopyrazole Derivatives,” is Ke
Zheng of TSRI. Other authors include Sarah Iqbal, Pamela Hernandez, HaJeung Park and Yangbo
Feng of TSRI. See http://pubs.acs.org/doi/abs/10.1021/jm501256y
Both studies were supported by the Department of Defense (W81XWH-12-1-0431 1192) and the
National Institutes of Health (GM103825).
Scripps Florida Scientists Discover a Key Pathway That Protects Cells Against Death by Stress
When it comes to protecting cells from death brought on by the calamities of environmental stress,
the human body is particularly ingenious. From cellular components that suck up misfolded proteins
to a vigilant immune system, the ways we protect our cells (and ourselves) are many and mysterious.
Scientists from the Florida campus of The Scripps Research Institute (TSRI) have now uncovered
the workings of another cell-protection device, one that may play a major role in a number of agerelated diseases, including diabetes and Parkinson’s, Alzheimer’s and Huntington’s diseases.
The study, led by Srinivasa Subramaniam, a TSRI assistant professor, and Solomon H. Snyder, a
neuroscience professor at Johns Hopkins University School of Medicine, was published February 5
in the journal Cell Reports.
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More or Less Acceleration
The study focuses on a new pathway through which Rheb, a regulator that many believe is active in
the brain’s ability to change in response to learning, actually plays two roles, rather than one—
stimulating and inhibiting protein synthesis.
The interplay between the two roles may be the key that enables cells to alter protein synthesis and
protect the cell in response to varying environmental stresses.
“We found Rheb acts like the gas pedal in a car,” Subramaniam said. “It can either increase
translation or decrease it. And because translation is a fundamental process that is affected in a lot of
diseases, we now think that Rheb may act like a switch in some disease states—helping to turn them
off and on.”
Rheb is known to bind and activate mTOR, a developmentally important gene that integrates signals
from multiple pathways and regulates critical cell functions such as protein synthesis. Besides its
role as an activator of mTOR, which plays a major role in conditions from diabetes to
neurodegenerative disease, the mTOR-independent role of Rheb is less known. The new study
defines crucial mTOR-independent effects of Rheb. Results showed that, when stressed, Rheb
instead inhibits protein synthesis by amplifying the phosphorylation (adding a phosphate group to a
protein to alter its function) of another protein known eIF2a. As a result, cell resources can be
conserved rather than squandered when the environment is challenging.
“We don’t really understand the full role of the Rheb-mTOR pathway, but we have uncovered a new
fundamental process of Rheb that is independent of mTOR and very intriguing,” said Neelam
Shahani, a member of Subramaniam’s lab who was co-first author of the study with Richa Tyagi of
Johns Hopkins University School of Medicine. “Rheb can inhibit protein synthesis, and we know
that protein misfolding via environmental stress factors is present in a lot of diseases.”
Subramaniam noted that, intriguingly, an earlier study had suggested the Rheb pathway had been
implicated in Alzheimer’s disease. “We also want to look at Rheb’s role in other neurodegenerative
diseases,” he said.
In addition to Subramaniam, Snyder, Shahani and Tyagi, authors of the study, “Rheb Inhibits Protein
Synthesis by Activating the PERK-eIF2α Signaling Cascade,” include Max Ferretti, William Pryor,
Supriya Swarnkar and Katrin Karbstein of TSRI; Lindsay Gorgen of Florida Atlantic University; as
well as Paul F. Worley and Po Yu Chen of Johns Hopkins University School of Medicine.
This work was supported by the State of Florida, the O'Keeffe Neuroscience Scholar Award and the
United States Public Health Service (DA000266).
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Scripps Florida Scientists' 'Mad Cow' Discovery Points to Possible Neuron Killing Mechanism
Behind Alzheimer’s and Parkinson’s Diseases
$1.4 Million Grant Will Enable Team to Follow Up with Search for Drug Candidates
Scientists from the Florida campus of The Scripps Research Institute (TSRI) have for the first time
discovered a killing mechanism that could underpin a range of the most intractable
neurodegenerative diseases such as Alzheimer’s, Parkinson’s and ALS.
The new study, published recently in the journal Brain, revealed the mechanism of toxicity of a
misfolded form of the protein that underlies prion diseases, such as bovine spongiform
encephalopathy (“mad cow disease”) and its human equivalent, Creutzfeldt-Jakob disease.
“Our study reveals a novel mechanism of neuronal death involved in a neurodegenerative proteinmisfolding disease,” said Corinne Lasmézas, a TSRI professor who led the study. “Importantly, the
death of these cells is preventable. In our study, ailing neurons in culture and in an animal model
were completely rescued by treatment, despite the continued presence of the toxic misfolded protein.
This work suggests treatment strategies for prion diseases—and possibly other protein misfolding
diseases such as Alzheimer’s.”
Failure and Rescue of Brain Cells
In the new study, the scientists used a misfolded form of the prion disease protein, called TPrP, a
model they had previously developed, to study misfolded protein-induced neurodegeneration in the
laboratory. Misfolded proteins are the common cause of the group of diseases comprising prion,
Alzheimer’s, Parkinson’s diseases, ALS and other conditions.
Using biochemical techniques, the researchers demonstrated that TPrP induces neuronal death by
profoundly depleting NAD+ (nicotinamide adenine dinucleotide)—a metabolite well known as a
coenzyme that is common to all cells and necessary for energy production and cellular homeostasis.
Restoring NAD+ proved to be the critical factor for the rescue of neurons subjected to TPrP injury.
Even when added three days after TPrP exposure, an infusion of NAD+ reversed within only a few
hours the fate of neurons that had been doomed to destruction.
“Our study shows for the first time that a failure of NAD+ metabolism is the cause of neuronal loss
following exposure to a misfolded protein,” Lasmézas said.
The loss of NAD+ also triggers autophagy—a way cells rid themselves of damaged material such as
misfolded proteins—and apoptosis, or programmed cell death, the last resort of the cell when
everything starts to go wrong. However, the researchers demonstrated these mechanisms do not
initiate the neuronal demise.
“We show that apoptosis or programmed cell death and autophagy are not primary players in the
death cascade,” said Staff Scientist Minghai Zhou, the first author of the study. “Modulation of
neither of these processes significantly alters the death of TPrP-exposed neurons. This is all caused
by NAD+ disappearing—the cell cannot survive without it.”
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Lasmézas noted the loss of NAD+ is suggestive of some other neurodegenerative diseases, such as
Parkinson’s where NAD+ depletion could play a role in mitochondrial failure.
New Grant to Support Further Research
A recent $1.4-million grant from the National Institute of Neurological Disorders and Stroke
(NINDS) will support further work to look for drug candidates based on the new findings.
Lasmézas and Louis Scampavia, a TSRI associate professor of molecular therapeutics, will be coprincipal investigators for the new three-year study, whose team will also include Tom Bannister, a
TSRI associate scientific director at Scripps Florida’s Translational Research Institute.
The scientists have developed several primary tests for compounds that could restore NAD+ and
plan to begin those tests at Scripps Florida’s High Throughput Screening facility.
Since it was established in 2005, the Scripps Florida High Throughput Screening facility has
screened more than 200 targets in more than 235 industrial and academic collaborations—several of
these collaborations have produced successful clinical trial candidates. The drug discovery facility is
currently capable of routinely screens one quarter of a million compounds in a single day.
In addition to Zhou and Lasmézas, other authors of the study, “Neuronal Death Induced by
Misfolded Prion Protein Is Due To NAD+ Depletion and Can Be Relieved In Vitro And In Vivo by
NAD+ Replenishment,” include Gregory Ottenberg, Gian Franco Sferrazza, Christopher Hubbs,
Mohammad Fallahi, Gavin Rumbaugh and Alicia F. Brantley of TSRI. The work was supported by
TSRI and by the National Institutes of Health (RNS081519).
The number of the new NINDS grant is 1R01NS085223.
Microbes Prevent Malnutrition in Fruit Flies—and Maybe Humans, Too
Microbes, small and ancient life forms, play a key role in maintaining life on Earth. As has often
been pointed out, without microbes, we’d die—without us, most microbes would get along just fine.
Now, a study by scientists from the Florida campus of The Scripps Research Institute (TSRI) sheds
significant new light on a surprising and critical role that microbes may play in nutritional disorders
such as protein malnutrition.
Using fruit flies—Drosophila melanogaster—as a simple and easily studied stand-in for humans,
these new findings advance our understanding of the fundamental mechanisms underlying microbial
contributions to metabolism and may point to long-term strategies to treat and prevent malnutrition
in general.
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In the study, published February 12 in the journal Cell Reports, a team led by TSRI biologist
William Ja showed that Issatchenkia orientalis, a fungal microbe isolated from field-caught fruit
flies, promotes nutritional harvest that rescues the health and longevity of undernourished flies.
Surprising Protein Harvest
Using a range of radioisotope-labeled dietary components such as amino acids (the components of
proteins and the basic building blocks of the body) and sucrose (sugar) to measure the transfer of
nutrients from food to microbe to fly, the study shows that the microbes first harvest amino acids
directly from the fly’s food sources and then transfer that protein to the fly—by being eaten.
“Flies in the wild carry microbes to every surface they touch,” said Research Associate Ryuichi
Yamada, who spearheaded the study in the Ja lab. “As flies land on low-protein fruit, they deposit
microbes, which take up and concentrate the available amino acids. By eating the microbes, flies
gain a much needed source of dietary protein.”
In flies that are fed nutrient-poor diets, this chain of events restores body mass and protein levels,
essentially returning them to the pre-malnutrition profile of well-fed flies.
“Ryuichi and colleagues did a lot of painstaking work to carefully show that the simplest explanation
for what was happening was correct,” Ja said. “The direct influence of microbes on fly nutrition is
often overlooked and may be relevant in numerous studies of host-microbe interactions.”
Natural Symbiosis
This relationship appears to be particularly beneficial for flies. Devouring the protein-plumped
microbes extends fly lifespan during periods when nutrients are scarce. “In fact, the I. orientalis
microbe is commonly found in field-trapped fruit flies,” said Yamada. “That suggests a natural
symbiosis.”
Ja believes the study also offers a larger lesson on the partnership that can occur between
microorganisms and their hosts, in addition to providing information on nutrient harvesting and the
potential of Drosophila as a platform for studies of host-microbe relationships.
“While everyone keeps looking for that single magic microbial metabolite or species, what has been
increasingly ignored is the bulk effect that microbes have on primary metabolism,” he said. “Our
study suggests that diverse [microbial] species could each benefit their hosts and that their quantity,
rather than quality, may be of fundamental importance.”
In addition to Ja and Yamada, other authors of the study, “Microbes Promote Amino Acid Harvest to
Rescue Undernutrition in Drosophila,” are Sonali A. Deshpande, Kimberley D. Bruce and Elizabeth
M. Mak of TSRI. For more information, see http://www.cell.com/cell-reports/home
The work was supported by the National Institutes of Health (grants R00AG030493 and
R21DK092735), The Ellison Medical Foundation and the Glenn Foundation for Medical Research.
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Scripps Florida Scientists Announce Anti-HIV Agent So Powerful It Can Work in a Vaccine
In a remarkable new advance against the virus that causes AIDS, scientists from The Scripps
Research Institute (TSRI) have announced the creation of a novel drug candidate that is so potent
and universally effective, it might work as part of an unconventional vaccine.
The research, which involved scientists from more than a dozen research institutions, was published
February 18 online ahead of print by the prestigious journal Nature.
The study shows that the new drug candidate blocks every strain of HIV-1, HIV-2 and SIV (simian
immunodeficiency virus) that has been isolated from humans or rhesus macaques, including the
hardest-to-stop variants. It also protects against much-higher doses of virus than occur in most
human transmission and does so for at least eight months after injection.
“Our compound is the broadest and most potent entry inhibitor described so far,” said Michael
Farzan, a professor on TSRI's Florida campus who led the effort. “Unlike antibodies, which fail to
neutralize a large fraction of HIV-1 strains, our protein has been effective against all strains tested,
raising the possibility it could offer an effective HIV vaccine alternative.”
Blocking a Second Site
When HIV infects a cell, it targets the CD4 lymphocyte, an integral part of the body’s immune
system. HIV fuses with the cell and inserts its own genetic material—in this case, single-stranded
RNA—and transforms the host cell into a HIV manufacturing site.
The new study builds on previous discoveries by the Farzan laboratory, which show that a coreceptor called CCR5 contains unusual modifications in its critical HIV-binding region, and that
proteins based on this region can be used to prevent infection.
With this knowledge, Farzan and his team developed the new drug candidate so that it binds to two
sites on the surface of the virus simultaneously, preventing entry of HIV into the host cell. “When
antibodies try to mimic the receptor, they touch a lot of other parts of the viral envelope that HIV can
change with ease,” said TSRI Research Associate Matthew Gardner, the first author of the study
with Lisa M. Kattenhorn of Harvard Medical School. “We’ve developed a direct mimic of the
receptors without providing many avenues that the virus can use to escape, so we catch every virus
thus far.”
The team also leveraged preexisting technology in designing a delivery vehicle—an engineered
adeno-associated virus, a small, relatively innocuous virus that causes no disease. Once injected into
muscle tissue, like HIV itself, the vehicle turns those cells into “factories” that could produce enough
of the new protective protein to last for years, perhaps decades, Farzan said.
Data from the new study showed the drug candidate binds to the envelope of HIV-1 more potently
than the best broadly neutralizing antibodies against the virus. Also, when macaque models were
inoculated with the drug candidate, they were protected from multiple challenges by SIV.
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“This is the culmination of more than a decade’s worth of work on the biochemistry of how HIV
enters cells,” Farzan said. “When we did our original work on CCR5, people thought it was
interesting, but no one saw the therapeutic potential. That potential is starting to be realized.”
In addition to Farzan, Gardner and Kattenhorn, authors of the study, “AAV-expressed eCD4-Ig
provides durable protection from multiple SHIV challenges,” include Hema R. Kondur, Tatyana
Dorfman, Charles C. Bailey, Christoph H. Fellinger, Vinita R. Josh and Brian D. Quinlan of TSRI;
Dennis R. Burton of the Department of Immunology and Microbial Science, the International AIDS
Vaccine Initiative’s (IAVI) Neutralizing Antibody Center, and the Center for HIV/AIDS Vaccine
Immunology and Immunogen Discovery (CHAVI-ID) at TSRI, and the Ragon Institute; Pascal
Poignard of the Department of the Immunology and Microbial Science, IAVI Neutralizing Antibody
Center, and CHAVI-ID at TSRI; Jessica J. Chiang and Annie Y. Yao of Harvard Medical School;
Michael D. Alpert of Harvard Medical School and Immunathon Inc.; Ronald C. Desrosiers of
Harvard Medical School and the University of Miami Miller School of Medicine; Kevin G. Haworth
and Paula M. Cannon of the University of Southern California; Julie M. Decker and Beatrice H.
Hahn of the University of Pennsylvania; Sebastian P. Fuchs and Jose M. Martinez-Navio of the
University of Miami Miller School of Medicine; Hugo Mouquet of The Rockefeller University and
Institut Pasteur; Michel C. Nussenzweig of The Rockefeller University and Howard Hughes Medical
Center; Jason Gorman, Baoshan Zhang and Peter D. Kwong of the National Institutes of Health;
Michael Piatak Jr. and Jeffrey D. Lifson of the Frederick National Laboratory for Cancer Research;
Guangping Gao of the University of Massachusetts Medical School; David T. Evans of the
University of Wisconsin; and Michael S. Seaman of Beth Israel Deaconess Medical Center.
The work was supported by the National Institutes of Health (grants R01 AI091476, R01 AI080324,
P01 AI100263, RR000168 and R01AI058715).
New Study Shows Decreased Aggressive Behavior Toward Strangers in Autism Spectrum
Disorder Model
While aggression toward caregivers and peers is a challenge faced by many individuals and families
dealing with autism, there has been much speculation in the media over the possibility of generally
heightened aggression in those diagnosed with autism spectrum disorder. A new study by scientists
from the Florida campus of The Scripps Research Institute (TSRI) found no evidence of increased
aggressive behavior toward strangers in an animal model of the condition.
In fact, the study, published recently online ahead of print in the journal Genes, Brain and Behavior,
found these animals showed decreased aggressive behavior toward strangers and, instead, engage in
more repetitive behavior than normal mice.
“These mice show traits relevant to autism, such as an overgrown brain and reduced social
interaction,” said Damon Page, a TSRI biologist who conducted the study with Research Associate
Amy Clipperton Allen. “What we don’t see in this model is a general increase in aggressive
behavior.”
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Autism spectrum disorder is a highly inheritable condition characterized by impaired social behavior
and communication skills and a tendency towards repetitive patterns of behavior. A 2010 survey of
eight-year-olds in 11 communities across the United States by the Centers for Disease Control and
Prevention (CDC) found a rate of autism spectrum disorder of approximately one in 68 children.
Boys, it found, are at four- to five-times greater risk than girls.
Page and his colleagues, who use animal models to understand how autism risk factors impact the
developing brain and to identify potential treatments for the condition, have found that animals with
mutations in the autism risk gene phosphatase and tensin homolog (Pten) mimic aspects of autism,
including increased brain size, social deficits and increased repetitive behavior. The new study used
the model to examine aggressive behavior directed at unfamiliar mice.
Typically, when an unfamiliar mouse is put into the “home” cage of another mouse, the resident will
attack the intruder, reflecting the natural tendency of mice to defend their territory.
That was not the case in the study. When a stranger mouse was placed in the home of a Pten-mutant
mouse, instead of attacking or investigating the intruder, these mutant animals engaged in repetitive
behavior—in this case, digging.
“This is a striking result,” Page said. “The mutant mice appear to avoid aggressive encounters with
the intruder and instead engage in repetitive behavior. An analogy might be a stranger entering a
house, and the resident rearranging the books on the bookshelf instead of confronting the intruder.”
Page plans further studies examining the neurobiological relationship between social deficits and
repetitive behavior, two of the primary symptoms of autism.
The study, “Decreased Aggression and Increased Repetitive Behavior in Pten Haploinsufficient
Mice,” was supported by Ms. Nancy Lurie Marks, The American Honda and Children’s Healthcare
Charity Inc. and the State of Florida. For more information on the study, see
http://onlinelibrary.wiley.com/doi/10.1111/gbb.12192/abstract
FAU, Scripps Florida, Max Planck Announce Plans for Groundbreaking Research and
Education Collaboration
One of Florida’s leading public research universities and two of the world’s premier research
institutions will create one-of-a-kind education programs that will attract the best and brightest
students to Palm Beach County, and transform Florida Atlantic University’s John D. MacArthur
Campus in Jupiter into a hub of scientific inquiry, innovation and economic development.
FAU, and the globally acclaimed Max Planck Florida Institute and The Scripps Research Institute,
will build on existing relationships to further scientific discovery and education through shared
resources and facilities.
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The three institutions will provide undergraduate and graduate students the unprecedented
opportunity to enroll in unique degree programs in collaboration with Max Planck and Scripps
Florida at the MacArthur Campus.
The initiative will allow students to work and study alongside some of the world’s leading scientific
researchers as part of their degree programs, while undergraduate research projects will be mentored
by these same scientists.
The Institutes will collaborate to develop premier STEM programs — Science, Technology,
Engineering, Math — and combine FAU Jupiter’s existing strengths in STEM areas, with support
from the arts, to create a leading STEAM initiative.
FAU President John Kelly said the alliance will help cure diseases, develop drugs, educate students
and generate jobs. FAU’s economic impact on Florida’s economy during 2010-2011, the most
recently available data, was $6.3 billion. This initiative creates unique opportunities for FAU’s
colleges of science, medicine, and engineering and computer science to greatly increase that number,
Kelly said.
“This initiative comes from the core of economic development,” Kelly said. “FAU, Max Planck and
Scripps will solve real-world problems and take strides to improve human health.
“We will create the knowledge economy of the future,” he said. “Moreover, we will provide students
unique scientific research programs that will be the envy of the world.”
A shared facilities environment will provide students access to state-of-the-art scientific equipment.
Max Planck and Scripps Florida researchers will have access to FAU faculty, teaching space, and
research equipment.
James Paulson, acting president and CEO of The Scripps Research Institute, said the Scripps mission
is to build a world-class biomedical research presence in Florida for the benefit of human health and
to train the next generation of scientists.
“We believe this new agreement strengthens our existing collaboration with FAU and the Max
Planck Institute and enables us to work more closely with our local partners to achieve these critical
goals,” Paulson said.
David Fitzpatrick, CEO and scientific director at Max Planck, said, importantly, the collaboration
will increase research funding in areas of common interest. The Max Planck Florida Institute’s
research focus is neuroscience, specifically, gaining insights into brain circuitry. The institute
utilizes some of the world’s most advanced technologies in brain research.
“Combining our resources makes this collaboration a potent force in the scientific and healthcare
fields,” Fitzpatrick said. “The advances we can take in many important research areas will be
significant.
“Together, FAU, Max Planck and Scripps will train the scientific leaders of tomorrow,” he said.
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Scripps Florida Scientists Find a Defect Responsible for Memory Impairment in Aging
Everyone worries about losing their memory as they grow older—memory loss remains one of the
most common complaints of the elderly. But the molecular reasons behind the processes remain
unclear, particularly those associated with advancing age.
Now, scientists from the Florida campus of The Scripps Research Institute (TSRI) have discovered a
mechanism that causes long-term memory loss due to age in Drosophila, the common fruit fly, a
widely recognized substitute for human memory studies.
The new study, published recently in The Journal of Neuroscience, describes in detail the loss of
connectivity between two sets of neurons that prevents the formation of long-term memory.
“We show how long-term memory is impaired with age in Drosophila,” said Ron Davis, a TSRI
professor and chair of the Department of Neuroscience who led the study. “This isn’t due to any
functional defects, but to connectivity problems between neurons.”
The most widely studied form of memory in fruit flies is memory of smell. When an odor is paired
with a mild electric shock, the flies develop short-term memories that persist for around a half-hour,
intermediate-term memory that lasts a few hours and long-term memory that persists for days.
Using real-time cellular imaging to monitor the changes in aged flies’ neuron activity before and
after learning, Davis and his colleague Ayako Tonoki found structural connectivity defects between
a set of neurons known as dorsal paired medial neurons and mushroom body neurons; these defects
prevented long-term memories from forming.
Long-term memories require new synapses and new proteins to be formed—as compared to shortterm memory, which is built from existing proteins.
“Now that we know long-term memory loss is a connection problem,” said Davis, “to improve
memory we’re going to have to think of ways of rebuilding those connections.”
The study, “Aging Impairs Protein-Synthesis-Dependent Long-Term Memory in Drosophila,” was
supported by the National Institutes of Health’s National Institute of Neurological Disorders and
Stroke (grant R37 NS19904) and by the Japan Society for the Promotion of Science (KAKENHI
Grants 25115703, 26115505 and 26830003). For more information on the study, see
http://www.jneurosci.org/content/35/3/1173.short
Scripps Research, Mayo Clinic Scientists Find New Class of Drugs that Dramatically Increases
Healthy Lifespan
A research team from The Scripps Research Institute (TSRI), Mayo Clinic and other institutions has
identified a new class of drugs that in animal models dramatically slows the aging process—
alleviating symptoms of frailty, improving cardiac function and extending a healthy lifespan.
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The new research was published March 9 online ahead of print by the journal Aging Cell.
The scientists coined the term “senolytics” for the new class of drugs.
“We view this study as a big, first step toward developing treatments that can be given safely to
patients to extend healthspan or to treat age-related diseases and disorders,” said TSRI Professor
Paul Robbins, PhD, who with Associate Professor Laura Niedernhofer, MD, PhD, led the research
efforts for the paper at Scripps Florida. “When senolytic agents, like the combination we identified,
are used clinically, the results could be transformative.”
“The prototypes of these senolytic agents have more than proven their ability to alleviate multiple
characteristics associated with aging,” said Mayo Clinic Professor James Kirkland, MD, PhD, senior
author of the new study. “It may eventually become feasible to delay, prevent, alleviate or even
reverse multiple chronic diseases and disabilities as a group, instead of just one at a time.”
Finding the Target
Senescent cells—cells that have stopped dividing—accumulate with age and accelerate the aging
process. Since the “healthspan” (time free of disease) in mice is enhanced by killing off these cells,
the scientists reasoned that finding treatments that accomplish this in humans could have tremendous
potential.
The scientists were faced with the question, though, of how to identify and target senescent cells
without damaging other cells.
The team suspected that senescent cells’ resistance to death by stress and damage could provide a
clue. Indeed, using transcript analysis, the researchers found that, like cancer cells, senescent cells
have increased expression of “pro-survival networks” that help them resist apoptosis or programmed
cell death. This finding provided key criteria to search for potential drug candidates.
Using these criteria, the team homed in on two available compounds—the cancer drug dasatinib
(sold under the trade name Sprycel®) and quercetin, a natural compound sold as a supplement that
acts as an antihistamine and anti-inflammatory.
Further testing in cell culture showed these compounds do indeed selectively induce death of
senescent cells. The two compounds had different strong points. Dasatinib eliminated senescent
human fat cell progenitors, while quercetin was more effective against senescent human endothelial
cells and mouse bone marrow stem cells. A combination of the two was most effective overall.
Remarkable Results
Next, the team looked at how these drugs affected health and aging in mice.
“In animal models, the compounds improved cardiovascular function and exercise endurance,
reduced osteoporosis and frailty, and extended healthspan,” said Niedernhofer, whose animal models
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of accelerated aging were used extensively in the study. “Remarkably, in some cases, these drugs did
so with only a single course of treatment.”
In old mice, cardiovascular function was improved within five days of a single dose of the drugs. A
single dose of a combination of the drugs led to improved exercise capacity in animals weakened by
radiation therapy used for cancer. The effect lasted for at least seven months following treatment
with the drugs. Periodic drug administration of mice with accelerated aging extended the healthspan
in the animals, delaying age-related symptoms, spine degeneration and osteoporosis.
The authors caution that more testing is needed before use in humans. They also note both drugs in
the study have possible side effects, at least with long-term treatment.
The researchers, however, remain upbeat about their findings’ potential. “Senescence is involved in
a number of diseases and pathologies so there could be any number of applications for these and
similar compounds,” Robbins said. “Also, we anticipate that treatment with senolytic drugs to clear
damaged cells would be infrequent, reducing the chance of side effects.”
The co-first authors of the study, “Achilles’ Heel of Senescent Cells: From Transcriptome to
Senolytic Drugs,” are Yi Zhu and Tamara Tchkonia of the Mayo Clinic.
In addition to Robbins, Niedernhofer and Kirkland, other authors include Sara J. McGowan, Heike
Fuhrmann-Stroissnigg, Aditi Gurkar, Jing Zhao, Debora Colangelo, Akaitz Dorronsoro, Yuan Yuan
Ling, Amira Barghouthy, Diana Navarro and Tokio Sano of TSRI; Yuji Ikeno and Gene Borden of
The University of Texas Health Science Center; Adam Gower and Marc Lenburg of Boston
University; Yi Zhu (co-first author), Tamara Tchkonia (co-first author), Tamar Pirtskhalava,
Husheng Ding, Nino Giorgadze, Allyson Palmer, Steven O'Hara, Nicholas LaRusso, Carolyn Roos,
Jordan Miller, Carolyn Roos, Grace Verzosa, Nathan LeBrasseur, Joshua Farr, Sundeep Khosla and
Michael Stout of Mayo Clinic; and Jonathan Wren of Oklahoma Medical Research Foundation. See
http://onlinelibrary.wiley.com/doi/10.1111/acel.12344/abstract
The work was supported by the National Institutes of Health (grants AG013925, AG041122,
AG031736, AG044396, DK050456, HL111121 and AG043376), the Glenn Foundation and the
Clinical & Translational Science Awards (grant UL1-TR000157).
Scripps Florida Scientists Confirm Key Targets of New Anti-Cancer Drug Candidates
Ribosomes, ancient molecular machines that produce proteins in cells, are required for cell growth in
all organisms, accomplishing strikingly complex tasks with apparent ease. But defects in the
assembly process and its regulation can lead to serious biological problems, including cancer.
Now, in a study published in the March 16 issue of The Journal of Cell Biology, scientists from the
Florida campus of The Scripps Research Institute (TSRI) have confirmed the ribosome assembly
process as a potentially fertile new target for anti-cancer drugs by detailing the essential function of a
key component in the assembly process.
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“This study confirms that ribosome assembly is a good therapeutic target in cancer,” said Katrin
Karbstein, a TSRI associate professor who led the study. “Whether or not we have pinpointed the
best molecule remains to be shown, but this is a vindication of our basic research. There should be
effort devoted to exploring this pathway.”
Understanding ribosome assembly—which involves about 200 essential proteins known as
"assembly factors" in addition to the four RNA molecules and 78 ribosomal proteins that are part of
the mature ribosome—has become a fruitful area of research in recent years because of the
importance of ribosome assembly for cell growth.
The new study highlights the molecules Casein kinase 1δ (CK1δ) and CK1ε, which are essential for
human ribosome assembly. The expression of CK1δ is elevated in several tumor types, as well as
Alzheimer’s and Parkinson’s disease—and CK1δ inhibitors have shown promise in some preclinical animal studies.
In the new study, Karbstein and her group—working closely with three labs across the state of
Florida, including the laboratory of William Roush at Scripps Florida—used Hrr25, the yeast
equivalent of Casein kinase 1δ (CK1δ) and CK1ε, as a research model.
In biochemical experiments, the team showed that Hrr25 is necessary for ribosome assembly and
that the molecule normally adds a phosphate group to an assembly factor called “Ltv1,” allowing it
to separate from other subunits and mature. If Hrr25 is inactivated or a mutation blocks the release of
Ltv1, the assembly process is doomed.
“Inhibiting Hrr25 and the subsequent release of Ltv1 blocks the formation of other subunits that are
required for maturation—and the subsequent production of proteins,” said Homa Ghalei, the first
author of the study and a member of the Karbstein lab.
In additional experiments on human breast cancer cells, the researchers showed that CK1δ/CK1ε
inhibitors no longer induce programmed cell death (“apoptosis”) and prevent cancer cells from
growing when Ltv1 is removed.
“This clearly establishes that the anti-proliferative potency of these inhibitors is in large part due to
blocking ribosome assembly,” Karbstein said.
In addition to Karbstein and Ghalei, other authors of the study, “Hrr25/CK1d-Directed Release of
Ltv1 From Pre-40S Ribosomes Is Necessary For Ribosome Assembly And Cell Growth”
(10.1083/jcb.201409056), are Joanne R. Doherty, Yoshihiko Noguchi and William R. Roush of
TSRI; Franz X. Schaub and John L. Cleveland of The Moffitt Cancer and Research Institute; and M.
Elizabeth Stroupe of Florida State University. See http://jcb.rupress.org/content/208/6/745.abstract
The work was supported by the National Institutes of Health (grants R01-GM086451, CA154739,
U54MH074404 and P30-CA076292), the National Science Foundation (grant 1149763), the
ThinkPink Kids Foundation, the PGA National Women’s Cancer Awareness Days and the Swiss
National Foundation (P300P3-147907).
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New Compound Prevents Type 1 Diabetes in Animal Models—Before It Begins
Scientists from the Florida campus of The Scripps Research Institute (TSRI) have successfully tested
a potent synthetic compound that prevents type 1 diabetes in animal models of the disease.
“The animals in our study never developed high blood sugar indicative of diabetes, and beta cell
damage was significantly reduced compared to animals that hadn’t been treated with our
compound,” said Laura Solt, Ph.D., a TSRI biologist who was the lead author of the study.
Type 1 diabetes is a consequence of the autoimmune destruction of insulin-producing beta cells in
the pancreas. While standard treatment for the disease aims to replace lost insulin, the new study
focuses instead on the possibility of preventing the initial devastation caused by the immune
system—stopping the disease before it even gets started.
In the study, published in the March 2015 issue of the journal Endocrinology, the scientists tested an
experimental compound known as SR1001 in non-obese diabetic animal models. The compound
targets a pair of “nuclear receptors” (RORα and RORg) that play critical roles in the development of
a specific population (Th17) of immune cells associated with the disease.
“Because Th17 cells have been linked to a number of autoimmune diseases, including multiple
sclerosis, we thought our compound might inhibit Th17 cells in type 1 diabetes and possibly
interfere with disease progression,” said Solt. “We were right.”
The researchers found SR1001 eliminated the incidence of diabetes and minimized insulitis, which is
the inflammation associated with, and destroyer of, insulin-producing cells, in the treated animals.
The compound suppressed the immune response, including the production of Th17 cells, while
maintaining normal insulin levels; it also increased the frequency of the expression of Foxp3 in T
cells, which controls the development and function of a type of immune cell known as T regulatory
cells.
Solt notes that the study strongly suggests that Th17 cells have a pathological role in the
development of type 1 diabetes and use of ROR-specific synthetic compounds targeting this cell type
may have potential as a preventative therapy for type 1 diabetes. “It certainly opens the door for
other areas to be looked at,” she said.
Other authors of the study, “ROR Inverse Agonist Suppresses Insulitis and Prevents Hyperglycemia
in a Mouse Model of Type 1 Diabetes,” include Subhashis Banerjee, Sean Campbell and Theodore
M. Kamenecka of The Scripps Research Institute, and Thomas Burris of Saint Louis University
School of Medicine. For more information on the study, see
http://press.endocrine.org/doi/pdf/10.1210/en.2014-1677
This work was supported by National Institutes of Health (grants DK080201, MH092769 and
DK089984) and a National Research Service Award (DK088499).
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Scripps Florida Scientists Reveal Unique Mechanism of Natural Product with Powerful
Antimicrobial Action
Scientists from the Florida campus of The Scripps Research Institute (TSRI) have uncovered the
unique mechanism of a powerful natural product with wide-ranging antifungal, antibacterial, antimalaria and anti-cancer effects.
The new study, published online ahead of print by the journal Nature Communications, sheds light
on the natural small molecule known as borrelidin.
“Our study may help the rational design of compounds similar to borrelidin with a range of useful
applications, particularly in cancer,” said Min Guo, a TSRI associate professor who led the study.
Powerful Medicines
Guo and his colleagues were interested in borrelidin because it inhibits a specific type of enzyme
known as threonyl-tRNA synthetase (ThrRS), ultimately impeding protein synthesis.
Compounds similar to borrelidin have been used as treatments for microbial infections. For example,
the natural product mupirocin is approved as a topical treatment for bacterial skin infections and
febrifugine (the active component of the Chinese herb Chang Shan (Dichroa febrifuga Lour)) has
been used for treating malaria-induced fever for nearly 2,000 years.
Previous studies from the collaborator Professor Christopher S. Francklyn of the University of
Vermont College of Medicine and others have shown that borrelidin impedes angiogenesis, the
growth of new blood vessels critical for the spread of malignant tumors, as well as increasing
apoptosis in certain types of leukemia.
“It is probably the most potent tRNA synthetase inhibitor on Earth,”said Research Associate
Pengfei Fang, co-first author of the study and member of the Guo lab at Scripps Florida. “It is also
the earliest known tRNA synthetase inhibitor, discovered in 1966—just a few years after people
learned the existence of tRNA synthetase and genetic code.”
Research Associate Xue Yu, also co-first author of the study and a member of the Guo lab,
emphasized, “While little is known about how borrelidin works, the fairly widespread use of these
types of inhibitors highlights their tremendous potential in a number of medical applications.”
Winning at Musical Chairs
In the new study, the scientists set out to conduct a detailed structural and functional analysis of the
binding of borrelidin to both human and bacterial (E. coli) ThrRS in the hope of identifying its
unique mechanism.
The researchers succeeded, and the new study shows for the first time that borrelidin occupies four
distinct subsites on both the bacterial and human tRNA synthetase, including all three subsites for its
normal binding substrates and an extra one that is created when the compound binds. In this way,
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borrelidin crowds out all natural partners that would otherwise bind those sites and fuel the process
of protein synthesis.
In that sense, borrelidin more or less wins the game of molecular musical chairs by taking over
everyone’s seat well before the music starts, even including the aisles.
Because each of the subsites is essential for its activity, the fact that borrelidin occupies four subsites
within ThrRS, an apparent inhibitory overkill, was a quite surprise, and indeed accounts for its
potency as validated by further experiments done in both in vitro and in cells.
“This has never been seen in any other tRNA synthetase inhibitors, including the ones sold as
medicines,” said Guo. “This finding establishes a new inhibitor class and highlights the striking
design of this natural compound that inhibits tRNA synthetases in two of the three kingdoms of life.”
In addition to Guo, Fang and Yu, other authors of the study, “Structural Basis for Full-Spectrum
Inhibition of Translational Functions on a tRNA Synthetase,” are Kaige Chen and Xin Chen of
TSRI; Seung Jae Jeong and Sunghoon Kim of Seoul National University, Korea; and Adam Mirando
and Christopher S. Francklyn of the University of Vermont College of Medicine.
The work was supported by the National Institutes of Health (grants NIEHS T32 ES007122-23,
GM54899, GM100136 and GM106134), the Korean Global Frontier Project (NRF-M1AXA0022010-0029785), and the PGA Women’s Cancer Awareness Foundation.
Scripps Florida Scientists Uncover How Molecule Protects Brain Cells in Parkinson’s Disease
Model
Scientists from the Florida campus of The Scripps Research Institute (TSRI) have found how a
widely known but little-studied enzyme protects brain cells in models of Parkinson’s disease.
These findings could provide valuable insight into the development of drug candidates that could
protect brain cells in Parkinson’s and other neurodegenerative diseases.
The study, published recently online ahead of print by the journal Molecular and Cellular Biology,
focuses on the enzyme known as serum glucocorticoid kinase 1 (SGK1).
“The overexpression of SGK1 provides neuron protection in both cell culture and in animal models,”
said Philip LoGrasso, a TSRI professor who led the study. “It decreases reactive oxygen species
generation and alleviates mitochondrial dysfunction.”
Using a neurotoxin animal model of neurodegeneration, the study showed that SGK1 protects brain
cells by blocking several pathways involved in neurodegeneration, deactivating other molecules
known as JNK, GSK3β and MKK4.
Increasing SGK1 offers a potential therapeutic strategy because, as the study makes clear, there isn’t
enough naturally occurring SGK1 to do the job.
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“Even though the levels of naturally occurring SGK1 increases in the cell under stress, it was not
enough to promote cell survival in our neurodegeneration model,” said Sarah Iqbal, the first author
of the study and a member of the LoGrasso lab. “On the other hand, cell survival mechanisms tend
to dominate when more SGK1 is added to the neurons.”
The LoGrasso lab plans to continue to explore SGK1 as a therapeutic possibility for Parkinson’s
disease.
In addition to LoGrasso and Iqbal, other authors of the study, “Serum-Glucocorticoid-Inducible
Kinase 1 Confers Protection in Cell-Based and in In Vivo Neurotoxin Models Via the C-Jun NTerminal Kinase Signaling Pathway,” include Shannon Howard of TSRI. For more information on
the study, see http://mcb.asm.org/content/early/2015/03/27/MCB.01510-14.full.pdf
The work was supported by the Department of Defense (grant W81XWH-12-1-0431), the National
Institutes of Health (grants U01-NS057153 and GM103825), the Michael J Fox Foundation/23&Me,
the Saul and Theresa Esman Foundation and a gift from the McCubbin Family.
Scripps Florida Scientists Uncover Surprising New Details of Potential Alzheimer’s Treatment
Taking a new approach, scientists from the Florida campus of The Scripps Research Institute (TSRI)
have uncovered some surprising details of a group of compounds that have shown significant
potential in stimulating the growth of brain cells and memory restoration in animal models that
mimic Alzheimer’s disease.
The new study points to promising new directions using a known therapeutic strategy for
Alzheimer’s disease—a disorder that will affect nearly 14 million Americans by 2050, according to
the Alzheimer’s Association.
The study, which was led by TSRI Associate Professors Courtney Miller and Gavin Rumbaugh,
appears online ahead of print in the journal Neuropsychopharmacology.
This new study builds on previous findings from Miller and Rumbaugh demonstrating the memoryrescuing potential of inhibiting histone deacetylases (HDACs), a family of signaling enzymes that
act like molecular switches, silencing gene expression by controlling access to the cell’s nuclear
cache of tightly compacted DNA. Mutations in HDACs genes have been associated with health
problems including cancer, inflammatory and autoimmune diseases, metabolic disorders and loss of
memory function.
Miller and Rumbaugh note that current efforts by many research teams focus on developing
“isoform-selective” HDAC inhibitors—for example, select members of Class 1 HDACs such as
HDAC 1, -2 or -3—in order to limit the potential for unwanted side effects. However, the Scripps
Florida researchers wondered if some of the potential of memory rescue could be lost with this
increased selectivity.
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To investigate, in the current study, the Scripps Florida team used inhibitors initially developed by
Professor Joel Gottesfeld, a molecular biologist on TSRI’s La Jolla campus, and subsequently by
biotech firm Repligen Corporation, to attack more than one form of Class 1 HDAC at the same time
in a mouse model of Alzheimer’s disease.
“We wanted to find out which inhibitors were the most selective and the most effective in restoring
memory function,” Miller said. “We found the key to memory restoration was the growth of new
synapses (synaptogenesis), which required simultaneous inhibition of multiple HDACs.”
“We found evidence that better synapse growth was associated with less specific inhibition of Class
1 HDACs,” Rumbaugh added. “There was a clear correlation between synapse building— which
may lead to improved network power—and memory restoration by the different HDAC inhibitors.”
Interestingly, memory was not enhanced in normal animals by chronic pretreatment with multiple
HDAC inhibitors, suggesting a diseased brain responds to these compounds differently than a
healthy brain.
In addition to Miller and Rumbaugh, who was first author the study with Research Associate
Stephanie E. Sillivan, other authors of the study, “Pharmacological Selectivity within Class I Histone
Deacetylases Predicts Effects On Synaptic Function and Memory Rescue,” include Emin D. Ozkan,
Camilo S. Rojas, Christopher R. Hubbs, Massimiliano Aceti and Sathyanarayanan V. Puthanveettil
of TSRI; Mark Kilgore and J. David Sweatt of The University of Alabama at Birmingham; and
Shashi Kudugunti and James Rusche of Repligen Corporation. For more information on the study,
See http://www.nature.com/npp/journal/vaop/ncurrent/full/npp201593a.html
The work was supported by the National Institute on Drug Abuse (R01DA034116; R03DA033499),
National Institute for Neurological Disorders and Stroke (R01NS064079; R21NS082640); National
Institute for Mental Health (R01MH096847; R01MH57014); and Repligen Corporation.
Scripps Florida Scientists Show Antitumor Agent Can Be Activated by Natural Response to
Cell Stress
Findings Point to New Therapy Against Prostate and Other Cancers
Scientists from the Florida campus of The Scripps Research Institute (TSRI) have found that a drug
candidate with anticancer potential can be activated by one of the body’s natural responses to
cellular stress. Once activated, the agent can kill prostate cancer cells.
“There is no proven drug right now with these activities,” said Ben Shen, vice chair of TSRI’s
Department of Chemistry and senior author of the new study, “so this points the way toward a new
therapeutic opportunity.”
The study, published recently by the journal Proceedings of the National Academy of
Sciences, highlights the potential of the natural compound called leinamycin (LNM) E1 for
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development as a “prodrug,” a medication converted through a metabolic process in the body to
become an active therapy.
Shen’s research has focused on developing natural products into potential therapies. As part of this
effort, he heads the Natural Products Initiative at TSRI, a library available for screening with 500
pure natural products, 2,000 fractions, and 7,500 crude extracts, prepared from 4,000
Actinomycetals.
Among these are “antitumor antibiotics” like LNM, which are produced by species of the soil
dwelling bacterium Streptomyces and are known to impede cancer cell growth and multiplication.
Some antitumor antibiotics are already in use as chemotherapy agents.
In the new study, the Scripps Florida team collaborated with scientists at the University of
Wisconsin, Madison to examine whether LNM E1 can be activated by reactive oxygen species,
which are naturally occurring molecules containing oxygen that play essential roles in cell signaling.
During times of stress, levels of reactive oxygen species can rise significantly and may trigger
apoptosis or programmed cell death. It is now widely accepted that many cancer cells are, by their
very nature, under high oxidative stress.
The results were promising. “Our study shows unambiguously that when LNM E1 is activated by
cellular reactive oxygen species, it causes DNA damage and cell death in cancer cells,” said Ming
Ma, co-first author of the study with Sheng-Xiong Huang.
The team further demonstrated the therapeutic potential of LNM E1 by showing it to be effective
against two prostate cancer cell lines, which are known to exist under high oxidative stress and with
increased levels of reactive oxygen species.
The study also reveals critical new insights into LNM biosynthesis, setting the stage to tailor
intermediate steps in the creation of new LNM analogues.
In addition to Shen, Ma and Huang, other authors of the study, “Leinamycin E1 Acting as an
Anticancer Prodrug Activated by Reactive Oxygen Species,” include Dong Yang and Jeremy R.
Lohman of TSRI; Bong-Sik Yun, Gudrun Ingenhorst, Yong Huang, Hirak S. Basu, Dawn R. Church,
Gong-Li Tang, Jianhua Ju and George Wilding of the University of Wisconsin-Madison.
The work was supported in part by the National Institutes of Health (grant CA106150).
New Study Brings Together Neuroscience and Psychology to Paint More Complete Picture of
Sleep and Memory
In Macbeth, Shakespeare describes sleep as “the death of each day’s life,” but he may have gotten it
wrong. Sleep, as it turns out, may be the one thing that keeps our memories alive and intact.
A new study from the Florida campus of The Scripps Research Institute (TSRI) integrates
neuroscience and psychological research to reveal how sleep is more complex than the Bard might
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have imagined. The new research, published online ahead of print by the journal Cell, shows in
animal models that sleep suppresses the activity of certain nerve cells that promote forgetting,
insuring that at least some memories will last.
“Many scientists have tried to figure out how we learn and how our memories become stabilized,”
said Ron Davis, chair of the TSRI Department of Neuroscience and senior author of the study. “But
far less attention has been paid to forgetting, which is a fundamental function for the brain and
potentially has profound consequences for the development of memory therapeutics. Our current
study merges the neuroscience of forgetting, that is, the brain mechanisms that lead to forgetting, and
the psychology of forgetting into an integrated picture.”
Early studies from psychology suggest that sleep facilitates memory retention by stopping
interference caused by mental and behavioral activity. That is, sleep essentially isolates the brain
from all of the stimuli that can interfere with memory storage. Neuroscience research, on the other
hand, suggests that sleep facilitates memory retention by enhancing memory stability or what is
called consolidation.
The new study in experimental animals reveals the biological underpinnings of the earlier
psychology studies, pointing to the activity of the neurotransmitter dopamine. Dopaminergic activity
is known to regulate various types of “plasticity”—the ability of the brain to change in direct
response to learning and memory formation. That ability includes forgetting as well.
The study shows that increasing sleep, with either a sleep-promoting drug or by genetic stimulation
of the neural sleep circuit, decreases signaling activity by dopamine, while at the same time
enhancing memory retention. Conversely, increasing arousal stimulates dopamine signaling and
accelerates forgetting. This signal activity isn’t constant but is tied directly to the animal’s arousal
level.
“Our findings add compelling evidence to support the model that sleep reduces the forgetting signal
in the brain, thereby keeping memories intact,” Davis said. “As sleep progresses to deeper levels,
dopamine neurons become less reactive to stimuli and this leads to more stable memories.
While the findings bolster earlier psychological studies, they are also not incompatible with more
recent findings in neuroscience. The authors note the effects of sleep on memory consolidation and
forgetting may operate in parallel and independently of one another or, more intriguingly, in serial in
a dependent fashion, with reduced forgetting a prerequisite for sleep-facilitated consolidation.
“We all know that sleep helps us remember,” said Research Associate Jacob A. Berry, the first
author of the study and a member of the Davis lab. “Importantly, we have revealed that one of the
ways sleep protects a new memory is by quieting dopamine neuron activity that causes forgetting.
Since laboratory animals and humans share a need for sleep, as well as many genetic and circuit
mechanisms underlying learning and memory, our findings may shed light on the mechanisms
underlying the interaction between sleep and memory in humans.”
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In addition to Davis and Berry, other authors of the study, “Sleep Facilitates Memory by Blocking
Dopamine Neuron-Mediated Forgetting,” are Isaac Cervantes-Sandoval and Molee Chakraborty of
TSRI.
This work was supported by the National Institutes of Health (grants R37 NS19904 and R01
NS051251).
Scripps Florida Scientists Uncover Unique Role of Nerve Cells in the Body’s Use of Energy
While it is well-known that weight gain results from an imbalance between what we eat and our
energy expenditure, what is not obvious is the role that the nervous system plays in controlling that
energy balance. Now scientists from the Florida campus of The Scripps Research Institute (TSRI)
have shed light on that question.
“Our new study has identified novel populations of nerve cells that regulate appetite, thermogenesis
and physical activity,” said TSRI Professor Baoji Xu, who led the research. “We think these neurons
could be targets for drug development.”
The findings were published by the journal Cell Metabolism online ahead of print on June 11.
In the new study, Xu and his colleagues examined several groups of neurons that express a substance
called “brain-derived neurotrophic factor” (BDNF) within a small brain region called the
paraventricular hypothalamus.
BDNF is an extremely important protein in the brain and is involved in a number of functions. It has
been shown that deleting the BDNF gene causes significant problems, among them, dramatically
increased appetite (hyperphagia) and severe obesity.
The new study shows that deleting the BDNF gene also impairs thermogenesis—the ability of cells
to burn fat to produce heat. The study further reveals two distinct types of BDNF neurons—those
that control appetite or satiety and those that control thermogenesis. Not only do these two groups
play different biological roles, they are located in two separate sections of the paraventricular
hypothalamus brain region.
This “geographical” split raises some interesting questions. “We don’t yet know what the distinctive
placement means to the control of body weight, nor do we know if these two clusters of neurons
communicate with each other as yet,” said Juanji An, the first author of the study and a member of
the Xu lab. “But given the fact that mice and humans with mutations in the BDNF gene or its
receptor develop severe obesity, a better understanding of the mechanism underlying the effect
BDNF has on body weight could provide great insights into the regulation of energy balance.”
Xu is also hopeful about the potential of BDNF as a drug target. “Our findings suggest that
activation of each of these two populations of neurons should powerfully suppress appetite or
promote energy expenditure,” he said. However, he cautions that because BDNF’s functions are so
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widespread, a good drug candidate would need to closely target only BDNF-expressing neurons in
the paraventricular hypothalamus, thus limiting potential side effects.
In addition to Xu and An, other authors of the study, “Discrete BDNF Neurons in the Paraventricular
Hypothalamus Control Feeding and Energy Expenditure,” include Guey-Ying Liao and Clint E.
Kinney of TSRI, and Niaz Sahibzada of the Georgetown University Medical Center. See
http://www.cell.com/cell-metabolism/home
The work was supported by grants from the National Institutes of Health (DK089237 and
DK103335) and the Klarman Foundation.
Scripps Florida Scientists Identify a Potential New Treatment for Osteoporosis
Scientists from the Florida campus of The Scripps Research Institute (TSRI) have identified a new
therapeutic approach that, while still preliminary, could promote the development of new boneforming cells in patients suffering from bone loss.
The study, published recently in the journal Nature Communications, focused on a protein called
PPARy (known as the master regulator of fat) and its impact on the fate of stem cells derived from
bone marrow (“mesenchymal stem cells”). Since these mesenchymal stem cells can develop into
several different cell types—including fat, connective tissues, bone and cartilage—they have a
number of potentially important therapeutic applications.
The scientists knew that a partial loss of PPARy in a genetically modified mouse model led to
increased bone formation. To see if they could mimic that effect using a drug candidate, the
researchers combined a variety of structural biology approaches to rationally design a new
compound that could repress the biological activity of PPARy.
The results showed that when human mesenchymal stem cells were treated with the new compound,
which they called SR2595 (SR=Scripps Research), there was a statistically significant increase in
osteoblast formation, a cell type known to form bone.
“These findings demonstrate for the first time a new therapeutic application for drugs targeting
PPARy, which has been the focus of efforts to develop insulin sensitizers to treat type 2 diabetes,”
said Patrick Griffin, chair of the Department of Molecular Therapeutics and director of the
Translational Research Institute at Scripps Florida. “We have already demonstrated SR2595 has
suitable properties for testing in mice; the next step is to perform an in-depth analysis of the drug’s
efficacy in animal models of bone loss, aging, obesity and diabetes.”
In addition to identifying a potential new therapeutic for bone loss, the study may have even broader
implications.
“Because PPARG is so closely related to several proteins with known roles in disease, we can
potentially apply these structural insights to design new compounds for a variety of therapeutic
applications,” said David P. Marciano, first author of the study, a recent graduate of TSRI’s PhD
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program and former member of the Griffin lab. “In addition, we now better understand how natural
molecules in our bodies regulate metabolic and bone homeostasis, and how unwanted changes can
underlie the pathogenesis of a disease.” Marciano will focus on this subject in his postdoctoral work
in the Department of Genetics at Stanford University.
In addition to Marciano and Griffin, other authors of the study, “Pharmacological Repression of
PPARγ Promotes Osteogenesis,” are Dana S. Kuruvilla, Siddaraju V. Boregowda, Alice Asteian,
Travis S. Hughes, Ruben D. Garcia-Ordonez, Scott J. Novick, Cesar A. Corzo, Tanya M. Khan,
Douglas J. Kojetin, Donald G. Phinney and Theodore M. Kamenecka of TSRI; and John B. Bruning
of The University of Adelaide (Australia). See http://www.nature.com/ncomms/index.html
The work was supported by the National Institutes of Health (grants DK08026, MH084512,
OD018254-01, DK097890, DK103116 and DK101871).
Scripps Florida Study Points to Drug Target for Huntington’s Disease
Huntington’s disease attacks the part of the brain that controls movement, destroying nerves with a
barrage of toxicity, yet leaves other parts relatively unscathed.
Scientists from the Florida campus of The Scripps Research Institute (TSRI) have established
conclusively that an activating protein, called “Rhes,” plays a pivotal role in focusing the toxicity of
Huntington’s in the striatum, a smallish section of the forebrain that controls body movement and is
potentially involved in other cognitive functions such as working memory.
“Our study definitively confirms the role of Rhes in Huntington’s disease,” said TSRI Assistant
Professor Srinivasa Subramaniam, who led the study. “Our next step should be to develop drugs that
inhibit its action.”
The study was published recently online ahead of print by the journal Neurobiology of Disease.
In an earlier study, Subramaniam and his colleagues showed that Rhes binds to a series of repeats in
the huntingtin protein (named for its association with Huntington’s disease), increasing the death of
neurons. The new study shows deleting Rhes significantly reduces behavioral problems in animal
models of the disease.
In addition, the study took the research further and revealed the effects of adding Rhes to the
cerebellum, a brain region normally not affected in Huntington’s.
Remarkably, Huntington disease animals injected with Rhes experienced an exacerbation of motor
issues, including loss of balance and coordination. Subramaniam and his colleagues also found
lesions and damaged neurons in the cerebellum, confirming Rhes is sufficient to promote toxicity
and showing that even those regions of the brain normally impervious to damage can become
vulnerable if Rhes is overexpressed.
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“Perhaps the biggest question to emerge from this study is whether Rhes is a good drug target for
Huntington’s disease,” Subramaniam said. “The short answer is ‘yes.’ Drugs that disrupt Rhes could
alleviate Huntington’s pathology and motor symptoms.”
“Many Huntington’s disease patients experience psychiatric-related problems, such as depression
and anxiety,” added Supriya Swarnkar, the first author of the study and a member of Subramaniam’s
lab. “But it’s unclear whether they are the cause or consequences of the disease. We think, by
targeting Rhes, we might block the initiation of Huntington’s, which we predict would afford
protection against psychiatric-related problems as well.”
In addition to Swarnkar and Subramaniam, other authors of the study, “Ectopic Expression of the
Striatal-enriched GTPase Rhes Elicits Cerebellar Degeneration and an Ataxia Phenotype in
Huntington Disease,” are Youjun Chen, William Pryor, Neelam Shahani and Damon Page of TSRI.
See http://www.sciencedirect.com/science/article/pii/S0969996115001850
The work was supported by the State of Florida.
Small RNAs Found to Play Important Roles in Memory Formation
Scientists from the Florida campus of The Scripps Research Institute (TSRI) have found that a type
of genetic material called “microRNA” plays surprisingly different roles in the formation of memory
in animal models. In some cases, these RNAs increase memory, while others decrease it.
“Our systematic screen offers an important first step toward the comprehensive identification of all
miRNAs and their potential targets that serve in gene networks important for normal learning and
memory,” said Ron Davis, chair of TSRI’s Department of Neuroscience who led the study. “This is
a valuable resource for future studies.”
The study was published in the June 2015 edition of the journal Genetics.
Unlike some types of RNA, microRNAs (miRNAs) do not code for proteins but instead regulate
various biological processes by modulating the level of gene expression. A number of studies have
shown that miRNAs are critical for normal development and cellular growth and may contribute to
the complexity of neurodegenerative diseases.
In the new study, 134 different miRNAs were tested for roles in learning and memory in the central
nervous system of Drosophila melanogaster, the common fruit fly, which is a recognized animal
model for memory studies.
The researchers tested the potential involvement of miRNAs in intermediate-term memory by
silencing them individually and identified at least five different miRNAs involved in memory
formation or retention.
“Among the five miRNAs identified in this study, we found one that is necessary for memory
formation,” said Research Associate Germain U. Busto, a first author of the study with Research
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Associate Tugba Guven-Ozkan. “Interestingly, its human counterpart is altered in several
neurodegenerative diseases, including Alzheimer’s and Huntington’s. It’s possible that this might be
a potential model to study and solve some specific aspects of those disorders.”
Surprisingly, the researchers found some miRNAs decreased memory formation, while others
increased it. The identified miRNAs affected either neuronal physiology underlying memory
formation or the development of the nervous system.
“These microRNAs are highly regulated during brain development and for adult brain function,”
said Guven-Ozkan. “When misregulated, they may exacerbate brain diseases like autism, and
Alzheimer’s and Huntington’s diseases. We’d like to pinpoint learning and memory pathways to
understand how they may lead to human disease.”
In addition to Davis, Busto and Guven-Ozkan, other authors of the study, “microRNAs That
Promote or Inhibit Memory Formation in Drosophila melanogaster,” include Tudor A. Fulga and
David Van Vactor of Harvard Medical School. For more information,
seehttp://www.genetics.org/content/200/2/569.abstract.
The work was supported by National Institutes of Health (grants R37 NS19904 and R01 NS069695).
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