Netrin1 exerts a chemorepulsive effect on migrating cerebellar interneurons in a Dcc-independent way.

Few studies have addressed the issue of how GABAergic interneurons in the cerebellar cortex migrate or what guidance cues steer them. Recent data show that their development starts at the cerebellar germinal epithelium on top of the fourth ventricle. These interneurons continue to proliferate in the postnatal cerebellar white matter and later migrate to their final position in the cerebellar cortex. Here we report the chemorepulsive action of Netrin1 on postnatal cerebellar interneurons in vitro and also show the expression pattern of Netrin1 and its receptors Dcc and Unc5. Our expression results further suggest that Netrin1 is involved in the migration of GABAergic interneurons in vivo. Moreover, our data point to Bergmann glial fibers as possible tracks for these cells en route to the molecular layer. Finally, experiments using blocking antibodies allow us to conclude that Dcc, although expressed by postnatal cerebellar interneurons, is not involved in the repulsive response triggered by Netrin1 in these cells.