E-cadherin is sorted by Rab7 and Snx16 for polarised secretion via Myosin V

Abstract

E-cadherin has a fundamental role in epithelial tissues by providing cell-cell adhesion. Epithelial homeostasis relies on polarised E-cadherin exocytosis to the lateral plasma membrane, however the secretion mechanisms are unknown. Epithelial plasticity depends on constant E-cadherin endocytosis and recycling, but it is unclear how recycling is facilitated. Here we use the Drosophila follicular epithelium to analyse E- cadherin recycling and secretion. We identify endosomes in the apical region of the epithelium, in which newly translated and endocytosed E-cadherin converge for polarised E-cadherin secretion. Our data provide evidence that Rab7 recruits Snx16 to these endosomes, and that Snx16 moves E-cadherin via tubulation into the Rab11 compartment. Rab11 forms E-cadherin transport vesicles by recruiting its effector Myosin V. We show in living follicles how Myosin V transports E-cadherin along an apical actin network to the zonula adherence. An additional secretion pathway exists in the basal epithelium, where Myosin V moves E-cadherin vesicles along parallel actin bundles to the plasma membrane.