VIB, Department of Molecular and Developmental Genetics, Program in Molecular and Developmental Genetics, Program in Cognitive and Molecular Neuroscience, Laboratory of Neuronal Communication, Herestraat 49, 3000 Leuven, Belgium.
Cell. 2011 Apr 1;145(1):117-32. doi: 10.1016/j.cell.2011.02.039.
Exchange of proteins at sorting endosomes is not only critical to numerous signaling pathways but also to receptor-mediated signaling and to pathogen entry into cells; however, how this process is regulated in synaptic vesicle cycling remains unexplored. In this work, we present evidence that loss of function of a single neuronally expressed GTPase activating protein (GAP), Skywalker (Sky) facilitates endosomal trafficking of synaptic vesicles at Drosophila neuromuscular junction boutons, chiefly by controlling Rab35 GTPase activity. Analyses of genetic interactions with the ESCRT machinery as well as chimeric ubiquitinated synaptic vesicle proteins indicate that endosomal trafficking facilitates the replacement of dysfunctional synaptic vesicle components. Consequently, sky mutants harbor a larger readily releasable pool of synaptic vesicles and show a dramatic increase in basal neurotransmitter release. Thus, the trafficking of vesicles via endosomes uncovered using sky mutants provides an elegant mechanism by which neurons may regulate synaptic vesicle rejuvenation and neurotransmitter release.
蛋白质在分拣内体中的交换不仅对许多信号通路至关重要，对受体介导的信号转导和病原体进入细胞也很重要；然而，突触囊泡循环中这一过程是如何被调控的仍不清楚。在这项工作中，我们提供的证据表明，单个神经元表达的 GTP 酶激活蛋白（GAP）Skywalker（Sky）的功能丧失会促进果蝇肌神经接点突触囊泡的内体运输，主要是通过控制 Rab35 GTP 酶的活性。与 ESCRT 机制以及嵌合泛素化突触囊泡蛋白的遗传相互作用分析表明，内体运输促进了功能失调的突触囊泡成分的替换。因此，sky 突变体拥有更大的、随时可释放的突触囊泡储备池，并且基础神经递质释放显著增加。因此，使用 sky 突变体发现的囊泡通过内体的运输为神经元调节突触囊泡更新和神经递质释放提供了一种优雅的机制。
