Transcriptional regulation of tangential neuronal migration in the developing forebrain.

In the developing brain, the tangential mode of migration appears as an efficient strategy for newly generated neurons to reach destinations that are far away from their site of origin, as opposed to local migration along radial glia process. The ganglionic eminence, in the vertebrate subpallium, is the main source of tangentially migrating neurons in the forebrain. However, little is known about the transcriptional control of such long-distance tangential migrations. Here, we review recent findings showing that homeodomain (HD) transcription factors (TFs) regulate the tangential migration of telencephalic neurons through the expression of several downstream targets including other TFs, axon guidance molecules, and cytoskeletal components. This molecular mechanism also seems to apply to tangentially migrating neurons in other parts of the brain.