Vesicle uncoating regulated by SH3-SH3 domain-mediated complex formation between endophilin and intersectin at synapses

© 2014 The Authors. Published under the terms of the CC BY NC ND 4.0 license. Neurotransmission involves the exo-endocytic cycling of synaptic vesicle (SV) membranes. Endocytic membrane retrieval and clathrin-mediated SV reformation require curvature-sensing and membrane-bending BAR domain proteins such as endophilin A. While their ability to sense and stabilize curved membranes facilitates membrane recruitment of BAR domain proteins, the precise mechanisms by which they are targeted to specific sites of SV recycling has remained unclear. Here, we demonstrate that the multi-domain scaffold intersectin 1 directly associates with endophilin A to facilitate vesicle uncoating at synapses. Knockout mice deficient in intersectin 1 accumulate clathrin-coated vesicles at synapses, a phenotype akin to loss of endophilin function. Intersectin 1/endophilin A1 complex formation is mediated by direct binding of the SH3B domain of intersectin to a non-canonical site on the SH3 domain of endophilin A1. Consistent with this, intersectin-binding defective mutant endophilin A1 fails to rescue clathrin accumulation at neuronal synapses derived from endophilin A1-3 triple knockout (TKO) mice. Our data support a model in which intersectin aids endophilin A recruitment to sites of clathrin-mediated SV recycling, thereby facilitating vesicle uncoating. Synopsis Neurotransmission requires endocytic membrane retrieval and clathrin-mediated reformation of synaptic vesicles. This study shows that intersectin 1 directly associates with the BAR domain protein endophilin to facilitate vesicle uncoating at synapses. Intersectin 1 knockout mice accumulate clathrin-coated vesicles akin to endophilin A loss. Intersectin via its SH3B domain directly binds to endophilin A. Intersectin binding is required for endophilin function in vesicle uncoating. Neurotransmission requires endocytic membrane retrieval and clathrin-mediated reformation of synaptic vesicles. This study shows that intersectin 1 directly associates with the BAR domain protein endophilin to facilitate vesicle uncoating at synapses.