Coupling cell cycle exit, neuronal differentiation and migration in cortical neurogenesis.

The generation of new neurons in the cerebral cortex requires that progenitor cells leave the cell cycle and activate specific programs of differentiation and migration. Genetic studies have identified some of the molecules controlling these cellular events, but how the different aspects of neurogenesis are integrated into a coherent developmental program remains unclear. One possible mechanism implicates multifunctional proteins that regulate, both cell cycle exit and cell differentiation.(1) A prime example is the cyclin-dependent kinase inhibitor p27(Kip1), which has recently been shown to function beyond cell cycle regulation and promote both neuronal differentiation and migration of newborn cortical neurons, through distinct and separable mechanisms. p27(Kip1) is therefore part of a machinery that couples the multiple events of neurogenesis in the cerebral cortex.