The GluN2B subunit of N-methy-D-asparate receptor regulates the radial migration of cortical neurons in vivo

• Using in utero electroporation, we examined the roles of NMDA in cortical development.
• Knockdown of GluN1 and GluN2B, not GluN2A, impaired cortical neuronal migration.
• Knockdown of GluN1 and GluN2B did not affect neuronal fate determination.
• Knockdown of GluN2B, not GluN1, enhanced dendritic complexity of the ecotopic neurons.

The formation of layered structure of the mammalian neocortex requires a fine organized migration of post-mitotic neurons during early development. However, whether the radial migration is regulated by NMDA receptor and specific subunits remains contradictory and unknown. Here, we reported that in the developing rat cortex, migration of presumptive layer II/III neurons to their deserved destination was regulated by NMDA receptors with GluN2B but not GluN2A subunit. Using in utero electroporation of small interference RNA (siRNA) of distinct NMDA receptor subunits, we found that knockdown GluN1 and GluN2B subunits dramatically delayed the neuronal migration to proper layer II/III, while improperly stayed at lower layers or even the germinal regions, without changing the cell fate. In contrast, knockdown of GluN2A subunit did not impair the neuronal migration. Additionally, the ecotopic neurons by GluN2B RNAi developed to well dendritic differentiation, while the ones by GluN1 RNAi still kept morphology of migrating neurons. Therefore, GluN2B subunit of NMDA receptor plays an essential role in regulating proper neuronal migration and cortical lamination.