WIP-1 and DBN-1 promote scission of endocytic vesicles by bridging actin and Dynamin-1 in the C. elegans intestine

Abstract

There has been a consensus that actin plays an important role in scission of the clathrin-coated pits (CCPs) besides the large GTPase Dynamin in metazoan cells. However, the recruitment, regulation, and functional interdependence of actin and Dynamin during this process remain inadequately understood. Here, based on small-scale screen and in vivo live-imaging techniques, we identified a novel set of molecules underlying CCP scission in the multicellular organism Caenorhabditis elegans. We found that loss of Wiskott−Aldrich syndrome protein (WASP)-interacting protein (WIP-1) impaired CCP scission, which is independent of WASP/N-WASP (WSP-1) and mediated by direct binding to G-actin. Moreover, the cortactin binding domain of WIP-1 serves as the binding interface for DBN-1/mAbp1, another actin-binding protein. We demonstrate that the interaction between DBN-1 and F-actin is essential for Dynamin-1 recruitment at endocytic sites. In addition, the recycling regulator RME-1/Eps15 homology (EH) domain-containing proteins is increasingly recruited at the arrested endocytic intermediates induced by F-actin loss or Dynamin-1 inactivation, which further stabilizes the tubular endocytic intermediates. Our study provides new insights into the molecular network underlying F-actin participation in the scission of CCPs.