A team of investigators at Brown University have found that Fragile X exists at the presynaptic, or sending side of the synapse. Previous research had only highlighted the role of the Fragile X protein on the receiving side of synaptic connections.
The scientists discovered that the Fragile X protein is only present in a small fraction of what are known as presynaptic specializations. The presynaptic Fragile X protein also turned out to be present in microscopic granules. Though further research is needed, the team hypothesizes that the granules contain multiple RNAs that help modify the synapse during learning and memory.
“The implication is that presynaptic defects could contribute to the pathology in autism in Fragile X,” says Justin Fallon, Ph.D., professor of neuroscience. “Almost no one has looked at the presynaptic side, as it was not thought to be involved in Fragile X.”
Their finding of the Fragile X granules was serendipity, according to Dr. Fallon. The original focus was on developing an improved method for visualizing where Fragile X protein sits in the brain. The research group began by examining specially prepared sections of mouse brain tissue with high-powered light and electron microscopes.
The article appears in the February 4 issue of the Journal of Neuroscience.