miR-182 regulates Slit2-mediated axon guidance by modulating the local translation of a specific mRNA

During brain wiring, mRNAs are trafficked into axons and growth cones where they are differentially translated in response to extrinsic signals. Differential control of local protein synthesis mediates neuronal compartment-specific behaviors that aid axon guidance. Yet little is understood about how specific mRNAs are selected for translation. Here we have investigated the local role of microRNAs (miRNAs) in mRNA-specific translation during axon pathfinding of Xenopus laevis retinal ganglion cell (RGC) axons. Profiling experiments revealed a rich repertoire of axonal miRNAs in developing RGC axons and identified miR-182 as one of the most abundant. Loss of miR182 impairs Slit2-induced growth cone repulsion and causes RGC axon targeting defects in vivo. To aid miRNA target prediction, we also profiled mRNA expression in RGC axons. Our results show that miR-182 targets cofilin1 mRNA in RGC growth cones and modulates its local translation in response to Slit2. Overall design: Two biological replicates, one condition