J Cell Biol

Collective endothelial migration during vascular development relies on dynamic cell-cell contacts, yet how the junctions between leader and follower cells are organized remains poorly understood. Using Cryo-SIM followed by FIB-SEM, we investigated the nanoscale 3D ultrastructure of asymmetric adherens junctions (AAJs), revealing a wide spectrum of membrane folds at the contact interface between migrating endothelial cells. By performing a junction localization screen, we identified a variety of membrane curvature-sensing BAR domain proteins selectively enriched at AAJs. Among these, BIN1 and SNX9 emerged as novel regulators of front-to-rear polarity in follower cells during endothelial collective migration. The spatiotemporal recruitment of these individual BAR proteins associated with distinct phases of AAJ remodeling. Furthermore, depletion of SNX9 disturbed VE-cadherin dynamics, endothelial cell directionality, and sheet migration in the common cardinal vein of zebrafish. These findings highlight junctional nanoscale membrane curvatures as hubs for the spatiotemporal recruitment of a repertoire of BAR proteins to remodel AAJs and guide collective endothelial migration during vascular development.