Making the neural plate to fold into a tube

Abstract

Neural tube formation is a critical morphological process for neural development. Its defect causes serious birth defects such as anencephaly and spina bifida. Neural tube formation is initiated by the bending of the neural plate, which is regulated by multiple processes, including planar cell polarity (PCP) signaling, convergent extension, and apical constriction. However, how each event proceeds at the molecular level and how they are coordinated into a sequential movement have not been fully understood. We have explored the mechanisms of neural plate bending, focusing on the role of the remodeling of the adherens junctions (AJ) in neuroepithelial cells. At limited regions of the bending neural plate, neuroepithelial cells apically constrict because of the contraction of actomyosin filaments lining the AJ, which is induced by the recruitment of ROCK/Rho kinase to these sites, and this process is thought to produce a force to bend the plate. We found that this contraction is mediolaterally polarized, and this polarized bending is controlled by a cooperation of PCP signals and actomyosin contraction. Thus, we uncovered a mechanism by which the neural plate bends mediolaterally to form a tube.