Pechstein Arndt, Gerth Fabian, Milosevic Ira, Jäpel Maria, Eichhorn-Grünig Marielle, Vorontsova Olga, Bacetic Jelena, Maritzen Tanja, Shupliakov Oleg, Freund Christian, Haucke Volker
Leibniz-Institut für Molekulare Pharmakologie (FMP), Berlin, Germany Department of Neuroscience, DBRM, Karolinska Institutet, Stockholm, Sweden.
Institute of Chemistry and Biochemistry, Freie Universität Berlin, Berlin, Germany.
EMBO Rep. 2015 Feb;16(2):232-9. doi: 10.15252/embr.201439260. Epub 2014 Dec 17.
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.
神经传递涉及突触小泡（SV）膜的外排 - 内吞循环。内吞膜回收和网格蛋白介导的SV重塑需要诸如发动蛋白A等能感知曲率和弯曲膜的BAR结构域蛋白。虽然它们感知和稳定弯曲膜的能力有助于BAR结构域蛋白在膜上的募集，但它们被靶向到SV循环特定位点的精确机制仍不清楚。在这里，我们证明多结构域支架蛋白相交蛋白1直接与发动蛋白A结合，以促进突触处囊泡脱包被。缺乏相交蛋白1的基因敲除小鼠在突触处积累网格蛋白包被的囊泡，这一表型类似于发动蛋白功能丧失。相交蛋白1/发动蛋白A1复合物的形成是由相交蛋白的SH3B结构域与发动蛋白A1的SH3结构域上的一个非典型位点直接结合介导的。与此一致，与相交蛋白结合缺陷的发动蛋白A1突变体无法挽救源自发动蛋白A1 - 3三联基因敲除（TKO）小鼠的神经元突触处的网格蛋白积累。我们的数据支持这样一个模型，即相交蛋白有助于发动蛋白A募集到网格蛋白介导的SV循环位点，从而促进囊泡脱包被。
