Developing Xenopus Laevis as a Model to Screen Drugs for Fragile X Syndrome
Final rept. 30 Sep 2012-31 Mar 2014
SCRIPPS RESEARCH INST LA JOLLA CA
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We sought to determine whether decreasing FMRP expression in Xenopus may help understand the consequences of loss of FMRP. We tested the effect of knocking down FMPR expression on visually guided behavior, seizure and brain development. We established a highly sensitive quantitative in vivo imaging assay to evaluate molecular genetic strategies to decrease FMRP expression in brain neurons and demonstrated the capacity to rescue the decreased FMRP expression by gene delivery. We characterized an innate visually-guided avoidance behavior in tadpoles and showed that the avoidance behavior shows rapid and long-lasting improvement after brief periods of training. Decreasing FMRP expression does not significantly impair visual avoidance behavior. We developed a second behavioral assay to evaluate the loss of FMRP in which animals are exposed to seizure-inducing drugs. Decreased FMRP expression increases seizure latency, which was partially compensated by gene delivery of an FMRP homolog. We demonstrated that knocking down FMRP expression in neural progenitor cells decreases neurogenesis, and that knocking down FMRP expression in differentiating neurons blocks the development of neuronal dendritic arbors. Our experiments are the first to demonstrate that loss of FMRP causes deficits in neurogenesis during brain development and indicate that these events may be important to target for novel therapeutics. Our studies demonstrate that Xenopus is a valuable system in which to model Fragile X Syndrome.
- Genetic Engineering and Molecular Biology
- Anatomy and Physiology
- Medicine and Medical Research