Researcher David Nelson, PhD, Explores New Cell Strategies for Fragile X Syndrome, FXTAS and FXPOI

David Nelson lab

It’s rare to find a researcher working on the Big Three — Fragile X Syndrome (FXS), Fragile X-associated Tremor/Ataxia Syndrome (FXTAS) and Fragile X-associated primary ovarian insufficiency (FXPOI). Then again, David Nelson, PhD, is the rare bird. Nelson is a professor of Molecular and Human Genetics, Baylor College of Medicine, and director of Baylor’s Graduate Program in Integrative Molecular and Biomedical Sciences. He has been involved in FXS research since the late 1980s where he helped identify the mutation and the FMR1 gene. These days, researchers in Nelson’s lab at Baylor are studying FXS, FXTAS and FXPOI using mouse models.

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Double Down: Fragile X Clinical Trial Combines Two Available Drugs

Fragile X clinical trial combines two available drugs

If all the science world’s a stage, Fragile X researchers are more than merely players. They are center stage. So believes Francois Corbin, MD, PhD, professor, Université de Sherbrooke, Canada, who directs the university’s Fragile X Clinic. Corbin, who has received more than $100,000 in FRAXA support since 2012, is leading a pilot randomized Phase II trial, exploring the tolerability and the synergistic effect of a combined therapy.

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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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FRAXA Grant to Nahum Sonenberg, PhD — Effects of metformin in Fmr1 knockout mouse model of Fragile X syndrome

Nahum Sonenberg

Mis-regulation of activity-dependent protein synthesis is one of the major cellular abnormalities found in Fragile X. Upstream neuronal signaling regulates a large cluster of enzymes called the mTORC1 complex, which in turn regulates protein synthesis. This complex is also controlled by cellular energy levels via the metabolic sensor AMP-activated Protein Kinase (AMPK). AMPK is a highly conserved kinase that is activated under conditions of energy stress, when intracellular ATP levels decline and intracellular AMP increases.

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Computational Analysis of Neural Circuit Disruption in Fragile X Model Mice

Computer modeling of the brain offers the hope of predicting how the brain responds to varying conditions, but these models have been rather primitive until recently. The Sejnowski team at the Salk Institute, who specialize in computational models of neural networks, will take the results of previous FRAXA-funded projects and incorporate them into their advanced computer models of brain function.

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Bcl-xL Inhibition as a Therapeutic Strategy for Fragile X Syndrome

Scientists have found increases in the numbers of neurons in brain regions of autistic children, suggesting a problem in developmental programmed cell death pathways. One of the most important effectors of neuronal survival during brain development is the “anti-cell death” protein Bcl-xL. While the normal function of Bcl-xL is to maintain a healthy number of neurons and synapses, over-expressed Bcl-xL can cause an overabundance of synaptic connections. This may be happening in Fragile X.

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Fragile X Syndrome Treatment Target: MMP-9

Iryna Ethell UC Riverside, FRAXA researcher

Dr. Ethell was awarded FRAXA Research Foundation funding from 2008-2011 and 2012-present. This latest work shows that human Fragile X tissues have elevated levels of the extracellular enzyme MMP-9, as well as an increase in the active fraction of that protein (like most enzymes, MMP-9 can exist in an inactive form which can be switched on rapidly; this kind of regulation is important in most biological pathways.)

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Scientists Uncover Trigger for Fragile X Syndrome

Samie Jaffrey, PhD, at Weill Medical College of Cornell University, FRAXA research grant

A new study led by Weill Cornell Medical College scientists shows that Fragile X syndrome occurs because of a mechanism that shuts off the gene associated with the disease. The findings, published today in Science, also show that a compound that blocks this silencing mechanism can prevent Fragile X syndrome – suggesting a similar therapy may be possible for 20 other diseases that range from mental retardation to multisystem failure.

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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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Fragile X Syndrome Protein Linked to Breast Cancer Progression

Claudia Bagni (VIB/KU Leuven, Belgium, and the University of Rome, Italy) and colleagues have identified the way Fragile X Mental Retardation Protein or FMRP contributes to the progression of breast cancer. The researchers demonstrated that FMRP acts as a master switch controlling the levels of several proteins involved in different stages of aggressive breast cancer, including the invasion of cancer cells into blood vessels and the spread of these cancer cells to other tissues forming metastasis.

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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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