On becoming neural: what the embryo can tell us about differentiating neural stem cells.

THE EARLIEST STEPS OF EMBRYONIC NEURAL DEVELOPMENT ARE ORCHESTRATED BY SETS OF TRANSCRIPTION FACTORS THAT CONTROL AT LEAST THREE PROCESSES: the maintenance of proliferative, pluripotent precursors that expand the neural ectoderm; their transition to neurally committed stem cells comprising the neural plate; and the onset of differentiation of neural progenitors. The transition from one step to the next requires the sequential activation of each gene set and then its down-regulation at the correct developmental times. Herein, we review how these gene sets interact in a transcriptional network to regulate these early steps in neural development.