Defining Subcellular Specificity of Metabotropic Glutamate Receptor (mGluR5) Antagonists

Karen O'Malley

With $217,500 in grants from FRAXA Research Foundation, Dr. Karen O’Malley and team studied the function of mGluR5 when it is inside cells. Many of the symptoms of Fragile X Syndrome (FXS) are thought to arise due to overactive metabotropic glutamate receptor 5 (mGluR5) signaling, which is normally opposed by the protein missing in FXS, Fragile X Protein (FMRP).

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Fragile X Mutant Mouse Models

David Nelson, PhD, FRAXA Investigator

With $375,000 in grants from the FRAXA Research Foundation since 2009, Dr. David Nelson has developed an impressive array of advanced mouse models of Fragile X, at Baylor College of Medicine. These models are available to investigators worldwide on request. This resource has been essential for a broad, rapid distribution of Fragile X and related gene mouse models and has increased the pace of Fragile X research.

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Fruit Flies to Model and Test Fragile X Treatments

Dr. Tom Jongens and Dr. Sean McBride study Fragile X Fruit Flies

Dr. Jongens and his collaborators have found an insulin-like protein in the fly brain that is overexpressed in the Fragile X mutant fly, leading to increased activity of the insulin signaling pathway. Furthermore, they found that certain behavioral patterns in the Fragile X flies can be rescued by expressing the FX gene just in insulin producing neurons in the fly brain. In the mutant, there are other changes in the signaling pathways, including a decrease in cAMP and elevation in PI3K, mTOR, Akt and ERK activity. They now propose to study 2 medicines used for diabetes: pioglitazone (increases cAMP and decreases Akt and ERK) and metformin (inhibits mTOR), in flies and mice to validate the potential efficacy of these novel therapeutics for Fragile X.

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Small Molecules To Target r(CGG) Expansions to Treat Fragile X Syndrome

With a 2-year, $90,000 grant from FRAXA Research Foundation, Dr.’s Matthew Disney and Wang-Yong Yang worked to correct the underlying problem in Fragile X: the silencing of the Fragile X gene (FMR1) and the resulting lack of FMRP (Fragile X Mental Retardation Protein). Their approach was to use novel small molecules to target the abnormal CGG repeats before the FMR1 gene.

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Potassium Channel Modulators to Treat Fragile X

With $246,000 in funding from FRAXA over 2012-2014, the Yale University team of Leonard Kaczmarek, PhD, showed that loss of FMRP leads to an increased Kv3.1 potassium currents and decreased Slack potassium currents in neurons. Both of these changes impair timing of action potentials in auditory neurons (and likely others throughout the brain). The team also found that the firing pattern of neurons in response to repeated stimulation is severely abnormal in Fragile X mice. Based on these results, they are collaborating with the UK-based company Autifony to develop and test advanced compounds which may reverse these deficits.

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Social Behavior as an Outcome Measure for Fragile X Clinical Trials

One of the features of the Fragile X mouse model which is relevant to the human Fragile X syndrome (and autism) is social behavior. Several tests show consistent social behavioral abnormalities in the Fragile X mouse model. With a $140,000 grant from FRAXA Research Foundation in 2012-2013, Dr. Willemsen at Erasmus University used social behavior tests to measure the effectiveness of several drug strategies.

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Matrix Metalloproteinase Therapeutic Treatments for Fragile X Syndrome

Kendal Broadie

With a $157,000 grant from the FRAXA Research Foundation in 2012-2013, Dr. Kendal Broadie and Dr. Cheryl Gatto worked to define the distinct but also overlapping roles for MMP-1 and MMP-2 in synaptic structural and functional development. In drug studies with Fragile X fruit flies, they will be testing a range of MMPIs in drug treatments to compare effectiveness during development and at maturity, in order to define the contributions of FXS developmental impairments and adult recovery/plasticity.

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Developing IPS cells to Screen Drugs which can Reactivate the FMR1 Gene

Anita Bhattacharyya, PhD

With $146,000 grant from FRAXA Research Foundation over 2012-2013, Drs. Anita Bhattacharyya and Xinyu Zhao at the University of Wisconsin developed a new mouse model of Fragile X syndrome which will enable testing of gene reactivation and gene therapy approaches to treatment. They transplanted human Fragile X neural cells differentiated from induced pluripotent stem cells into brains of neonatal mice and then testing for FMR1 reactivation. In 2015, The John Merck Fund assumed support for this work with a generous grant of $750,000 to the scientists. Results published.

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Synaptic Actin Signaling Pathways in Fragile X

With a $163,356 grant from FRAXA Research Foundation in 2010-12, Dr. Scott Soderling and Dr. Hwan Kim at Duke University bred the standard mouse model of Fragile X syndrome to their lines of mice that express reduced levels of several key proteins that modulate synaptic actin. These compound mutant mice were compared to FXS mice to determine if genetically impairing pathways to the actin cytoskeleton can rescue deficits in the FXS mice.

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