The planar cell polarity (PCP) pathway regulates the polarization of epithelial tissues in various contexts, but recent studies suggest that the PCP pathway also influences other aspects of morphogenesis. Here, Sergei Sokol and colleagues uncover a role for PCP signalling during apical constriction in Xenopus embryos (p. ). They show that the core PCP protein Vangl2 accumulates at the apical surface of blastopore bottle cells, which undergo apical constriction during gastrulation. The depletion of Vangl2 perturbs apical constriction and hence blastopore formation. The authors further demonstrate that Rab11, a marker of the recycling endosome, localizes to the apical surface of constricting cells in a Vangl2-dependent manner; apical staining of Rab11 is absent in Vangl2-depleted embryos, suggesting that PCP signalling modulates endocytic trafficking. Finally, the authors show that Rab11 in turn modulates Vangl2 distribution and that it cooperates with Myosin V to regulate apical constriction. Together, these studies highlight a novel role for the PCP pathway during apical constriction and support a positive-feedback model in which both PCP signalling and endocytic trafficking function to regulate apical constriction.
