During morphogenesis, the elongation of polarised tissues involves cells within epithelial sheets and tubes making and breaking intercellular contacts in an oriented manner. How cells remodel their junctional contacts is poorly understood but growing evidence suggests that localised endocytic trafficking of E-cadherin might modulate cell adhesion. Now, Samantha Warrington and co-workers () report that the Frizzled-dependent core planar polarity pathway, which has been implicated in the regulation of cell adhesion through E-cadherin trafficking, promotes polarised cell rearrangements in Drosophila. The researchers report that the core planar polarity pathway promotes cell intercalation during tracheal tube morphogenesis by promoting E-cadherin turnover at junctions through local recruitment and regulation of the guanine exchange factor RhoGEF2. Core planar polarity pathway activity also leads to planar-polarised recruitment of RhoGEF2 and E-cadherin in the epidermis of the embryonic germband and the pupal wing. Thus, the researchers suggest, local promotion of E-cadherin endocytosis through recruitment of RhoGEF2 is a general mechanism by which the core planar polarity pathway promotes polarised cell rearrangements.
