Sil, P.; Trejo, B.; Little, K. A.; Devenport, D.

Planar cell polarity (PCP) in epithelia is characterized by the polarized distribution of two opposing, membrane-associated PCP complexes across cell junctions. Transmembrane components of the PCP complex bridge cell junctions and organize into punctate, intercellular assemblies that exhibit a high degree of stability. Here, we define the contributions of the cytoplasmic PCP protein, Dishevelled (Dvl), in the sub-micron scale organization and stability of PCP complexes. Using endogenously-tagged fluorescent PCP reporters in the embryonic mouse epidermis, we quantify PCP protein mobility and clustering during polarization. We find that as transmembrane proteins immobilize into puncta, Dishevelled (Dvl2/3) co accumulates with its transmembrane partner Frizzled (Fz6) in a polarized manner and stabilizes clusters of PCP complexes. We identify a previously unknown function for the oligomerizing DIX domain of Dvl3, typically associated with Wnt signaling, in Dvl3 asymmetric localization. These observations underscore a role for Dvl oligomerization in assembly and stabilization of asymmetric PCP puncta.