Planar cell polarity signaling in neural development.

Planar cell polarity (PCP), the organization of cell sheets in the tangential plane, is regulated by a set of 'core' PCP genes. Over the last few years, evidence has accumulated that PCP signaling is important for brain development and function. PCP signaling in the neuroepithelium and otic placode controls neural tube closure, the organization of inner ear sensory cells and probably neural stem cell divisions. PCP signaling also acts in postmitotic neurons, and regulates neuronal migration, axon guidance as well as neuronal maturation and survival. Although several key players in PCP signaling have been identified, their mechanisms of action remain elusive, particularly in the nervous system.