Project Summary Neurons have highly specialized structures and functions; their genetic information is often located a great distance from the sites where information gets transmitted, and they must dynamically alter the synaptic proteome in response to neural activity. These challenges indicate that neurons have evolved unique regulatory mechanisms to meet functional demands. The uniformity of DNA across different cell types suggests that how genetic information is unfolded and processed underlies cellular diversity. In this view, careful examination of the regulation of RNA metabolism, how pre-mRNA gene copies are alternatively spliced and polyadenylated, edited, localized, and translationally regulated, will offer a new avenue towards understanding complex processes, such as synaptic plasticity underlying learning and memory. This notion has driven molecular neuroscientists to search for factors that localize and regulate synaptic RNAs. We are only beginning to compile a list of these key regulators, such as RNA binding proteins (RBPs), particularly in the synapses of hippocampal neurons that are involved in memory, and to date very little is known about how these factors regulate RNA. Our laboratory has recently generated a new platform for cell-specific Crosslinked Immunoprecipitation (CLIP) of RBPs in the living brain of mice (cTag-CLIP), which has furthered our understanding of the cell-specific regulatory functions of RBPs; however, this technology is limited to looking at steady state RNA regulation. Here we described a novel approach to uncover the role of neuronal RBP-mediated RNA regulation in the context of synaptic plasticity. This methodology, termed opto-CLIP, will combine the cell type-specific resolution afforded by cTag-CLIP with the unprecedented precision of optogenetics to achieve non-invasive optical control of specific neurons. Once established, we will increase the cellular resolution by performing opto-CLIP in distinct subcellular compartments to assess local RNA regulation associated with neuronal function. This study will further our understanding of RBP-mediated RNA regulation, enhance our knowledge of the role of RNA metabolism in synaptic plasticity, and provide new insight into the pathological mechanisms underlying neurological disorders. In conclusion, I am confident that my experience studying RNA biology, the Darnell lab's foundation in neuroscience and CLIP, and the rich research environment at Rockefeller University will help me succeed in using optogenetics to study the role of RBP-mediated RNA regulation in synaptic plasticity.