Role of epsin 1 in synaptic vesicle endocytosis
Role of epsin 1 in synaptic vesicle endocytosis
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DOI：
10.1073/pnas.0710267105
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发表时间：
2008-04-29
影响因子：
11.1
通讯作者：
Brodin, Lennart
中科院分区：
文献类型：
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作者：
Jakobsson, Joel;Gad, Helge;Brodin, Lennart
已经提出Epsin在几种内吞途径中充当替代适配器。然而，它在突触囊泡再循环中的作用仍然不清楚。在这里，我们研究的作用，epsin在这一过程中使用七鳃鳗网状脊髓突触作为模型系统。我们对七鳃鳗epsin 1的直系同源物进行了表征，并表明它在静息时积聚在释放位点，并且在突触活动期间也积聚在周活跃区的网格蛋白包被的小坑处。通过突触前显微注射抗体到epsin-N-末端同源结构域（ENTH）或网格蛋白/AP 2结合区（CLAP），破坏epsin相互作用，导致受刺激突触中囊泡的严重损失。CLAP抗体注射的突触显示大量积累的扭曲的涂层结构，包括涂层空泡，而在突触干扰与ENTH抗体，很少的涂层结构被发现。在这两种情况下，在质膜上的涂层坑显示了转变为早期中间体（浅涂层坑）和尺寸的增加。此外，在CLAP抗体注射突触平坦网格蛋白包被的补丁发生在质膜上。我们的结论是，epsin参与网格蛋白介导的突触囊泡内吞。我们的研究结果支持一个模型，在体外研究的基础上，表明胰蛋白酶协调曲率生成与外套组装，并进一步表明，胰蛋白酶限制网格蛋白外套组装新形成的囊泡的大小。我们认为，epsin 1的这些功能提供了一个额外的机制，产生大小均匀的突触囊泡。
Epsin has been suggested to act as an alternate adaptor in several endocytic pathways. Its role in synaptic vesicle recycling remains, however, unclear. Here, we examined the role of epsin in this process by using the lamprey reticulospinal synapse as a model system. We characterized a lamprey ortholog of epsin 1 and showed that it is accumulated at release sites at rest and also at clathrin-coated pits in the periactive zone during synaptic activity. Disruption of epsin interactions, by presynaptic microinjection of antibodies to either the epsin-N-terminal homology domain (ENTH) or the clathrin/AP2 binding region (CLAP), caused profound loss of vesicles in stimulated synapses. CLAP anti body-injected synapses displayed a massive accumulation of distorted coated structures, including coated vacuoles, whereas in synapses perturbed with ENTH antibodies, very few coated structures were found. In both cases coated pits on the plasma membrane showed a shift to early intermediates (shallow coated pits) and an increase in size. Moreover, in CLAP antibody-injected synapses flat clathrin-coated patches occurred on the plasma membrane. We conclude that epsin is involved in clathrin-mediated synaptic vesicle endocytosis. Our results support a model, based on in vitro studies, suggesting that epsin coordinates curvature generation with coat assembly and further indicating that epsin limits clathrin coat assembly to the size of newly formed vesicles. We propose that these functions of epsin 1 provide an additional mechanism for generation of uniformly sized synaptic vesicles.