Abstract
Fragile X-associated tremor/ataxia syndrome (FXTAS) is a genetic disease characterized by impaired movement coordination, peripheral nervous system damage, limb tremors, cognitive decline, behavioral changes, autonomic nervous system dysfunction, intellectual disability, and Parkinson’s disease like symptoms. FXTAS usually manifests after the age of 50 and affects 1 out of 3000 men and 1 out of 5200 women. FXTAS is theorized to be the result of an expansion of CGG repeats in the 5’ untranslated region (UTR) of the Fragile-X mental retardation 1 (FMR1) gene. FXTAS is one of many disease phenotypes caused by the premutation FMR1 allele. In the United States it is estimated that 1.7 million women and 750,000 men carry the premutation allele and puts them at risk for hypertension, seizures, muscle pain, sensory, and the already mentioned FXTAS. FMR1 encodes for the fragile-X mental retardation protein (FMRP) and it inhibits translation by binding to large number of mRNA transcripts, up to 4% of the total RNA in the nervous system. The specific molecular cause of premutation v phenotypes is not known but is theorized to be caused by FMRP reduction, RNA toxicgain of function, or some combination of the two. Studies have shown that premutation has an effect on radial glial stem cells and intermediate progenitors during embryonic development. This study validated a new FMR1 shRNA called GI377 and used RNA interference technique with the shRNA ED03 to experimentally reduce FMRP concentrations in radial glial stem cells and their differentiated daughter cells in embryonic normal type mouse brain. This study determined that, as predicted, the quantity of intermediate progentiors in the ventricular and subventricular zones of the somatosensory cortex decreased when FMRP was knocked down. This evidence is not sufficient to conclude cause nor is it sufficient to rule out other interacting characters. Our work furthers premutation research through the validation of a new shRNA and further adds value to the field through determining that FMRP knockdown alone reduces intermediate progenitor quantity and suggests a differentiation bias towards glial cell fate when FMRP is reduced. FXTAS and other premutation disease have large effects on the lives of those afflicted, their family, and their friends. Discerning the mechanism through which premutation manifests will enable future research to discover cell, gene, and molecular therapies which could reduce or prevent the premutation from manifesting.