Possible roles of Plexin-A4 in positioning of oligodendrocyte precursor cells in developing cerebral cortex

Molecular mechanisms regulating positions of oligodendrocyte precursor cells (OPCs) remain unclear in developing cerebral cortex. To explore the mechanisms, we investigated how Plexin-A4, receptor of Semaphorin in OPCs, is involved in the positioning. We found that Plexin-A4 knockout mice exhibited (1) an increased number of OPCs in both the upper- and middle-regions of the cortical plate, where both indirect- and direct-ligands of Plexin-A4, Sema3A and Sema6A, respectively, were continuously expressed, and (2) aberrant distributions of OPCs in both the intermediate zone and corpus callosum, where Plexin-A4 was richly expressed in wild-type mice. These results suggest that Plexin-A4 is involved in the precise positioning of OPCs in developing cerebral cortex.

► Distribution of OPCs was disturbed in the cortical plate in Plexin-A4 mutants.
► Both Sema3A and Sema6A were continuously expressed in the cortical plate.
► Number of OPCs was also decreased in the corpus callosum of the mutants.