Sorting of striatal and cortical interneurons regulated by semaphorin-neuropilin interactions

Most striatal and cortical interneurons arise from the basal telencephalon, later segregating to their respective targets. Here, we show that migratin g cortical interneurons avoid entering the striatum because of a chemorepul sive signal composed at least in part of semaphorin 3A and semaphorin 3F. M igrating interneurons expressing neuropilins, receptors for semaphorins, ar e directed to the cortex; those lacking them go to the striatum. Loss of ne uropilin function increases the number of interneurons that migrate into th e striatum. These observations reveal a mechanism by which neuropilins medi ate sorting of distinct neuronal populations into different brain structure s, and provide evidence that, in addition to guiding axons, these receptors also control neuronal migration in the central nervous system.