Distal mRNA localization and translation in neural stem cells of the developing brain

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Abstract mRNA localization and local translation are conserved mechanisms enabling spatial and temporal control of gene expression. These processes are particularly important in the nervous system, where local regulation of gene expression influences axon guidance and synaptic activity. Much of our understanding of mRNA localization and local translation has relied upon in vitro studies. We recently established a novel tractable in vivo paradigm for investigating local gene regulation in vivo in the developing nervous system. Specifically we found that mRNA is sub-cellularly localized and locally translated in basal structures of embryonic radial glial cells (RGCs), called endfeet. These basal structures are essential for tissue integrity and neuronal migration, thus impacting the central function of RGCs in neuron generation. We developed live imaging approaches to discover that mRNA can be actively transported in RGCs and locally translated in basal endfeet. We also developed novel methods to isolate RGC endfeet and used these to discover a local transcriptome in endfeet, bound by the RNA binding protein, FMRP. Our studies lead us to hypothesize that RNA localization and local translation are intrinsically and extrinsically regulated in RGC endfeet to influence signaling and the cytoskeleton. In this proposal we aim to implement these new molecular imaging and genomic tools towards: (1) discovering local transcriptomes of RGC endfeet across development, (2) determining intrinsic and extrinsic regulation of translation in RGC endfeet, and (3) defining functions for RNA localization in RGC endfeet. Successfully completed, we will have significantly advanced our understanding of mRNA localization and translation in the developing nervous system, by studying these processes in an in vivo model.