Planar cell polarity governs the alignment of the nasopharyngeal epithelium in mammals

Planar cell polarity (PCP) signalling specifies the orientation of epithelial cells and regulates directional beating of motile cilia of multiciliated epithelial cells. Clinically, defects in cilia function are associated with nasopharyngeal symptoms. The polarity of the nasopharyngeal epithelium is poorly understood. Here, we demonstrated PCP in the nasopharyngeal epithelium. Multiciliated cells (MCCs) were uniformly aligned with their long axis parallel to the tissue axis of the nasopharynx (NP). In addition, PCP proteins exhibited an asymmetrical localisation between adjacent cells. Motile cilia were uniformly aligned in the same direction within both individual cells and neighbouring cells, which manifested as cilial polarity in MCCs. Mutation of Vangl2, a mammalian homologue of the Drosophila PCP gene, resulted in significant disruption of the orientation of epithelial cells. Finally, keratin-5-positive basal cells constantly replenished the luminal ciliated cells; the new dynamic ciliated cells were also oriented parallel to the tissue axis. These results indicate a role for the PCP pathway in the uniform orientation of dynamically replenished epithelial cells in the NP.