SummaryWnts activate at least two signaling pathways, the b-catenin-dependent and -independent pathways. Although the b-catenin-dependent pathway is known to contribute to G1-S transition, involvement of the b-catenin-independent pathway in cell cycle regulation remains unclear. Here, we show that Wnt5a signaling, which activates the b-catenin-independent pathway, is required for cytokinesis. Dishevelled 2 (Dvl2), a mediator of Wnt signaling pathways, was localized to the midbody during cytokinesis. Beside the localization of Dvl2, Fz2, a Wnt receptor, was detected in the midbody with the endosomal sorting complex required for transport III (ESCRT-III) subunit, CHMP4B. Depletion of Wnt5a, its receptors, and Dvl increased multinucleation. The phenotype observed in Wnt5a-depleted cells was rescued by the addition of purified Wnt5a but not Wnt3a, which is a ligand for the b-catenin-dependent pathway. Moreover, depletion of Wnt5a signaling caused loss of stabilized microtubules and mislocalization of CHMP4B at the midbody, which affected abscission. Inhibition of the stabilization of microtubules at the midbody led to the mislocalization of CHMP4B, while depletion of CHMP4B did not affect the stabilization of microtubules, suggesting that the correct localization of CHMP4B depends on microtubules. Fz2 was localized to the midbody in a Rab11-dependent manner, probably along stabilized microtubules. Fz2 formed a complex with CHMP4B upon Wnt5a stimulation and was required for proper localization of CHMP4B at the midbody, while CHMP4B was not necessary for the localization of Fz2. These results suggest that Wnt5a signaling positions ESCRT-III in the midbody properly for abscission by stabilizing midbody microtubules.

Wnt signal plays important roles in polarization. Here intestinal epithelial cells are shown to form apicobasal polarization at a single-cell level in an extracellular matrix adhesion–dependent manner. Wnt5a signaling promotes single-cell polarization through balanced control between Rac1 and RhoA activities spatially.