α-Synuclein Membrane Association Is Regulated by the Rab3a Recycling Machinery and Presynaptic Activity
α-Synuclein Membrane Association Is Regulated by the Rab3a Recycling Machinery and Presynaptic Activity
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DOI：
10.1074/jbc.m112.439497
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发表时间：
2013-03-15
影响因子：
4.8
通讯作者：
Tandon, Anurag
中科院分区：
文献类型：
--
作者：
Chen, Robert H. C.;Wislet-Gendebien, Sabine;Tandon, Anurag
突触核蛋白是一种丰富的突触前蛋白，是帕金森病路易小体的主要成分。尽管其致病作用尚不清楚，但在健康的神经末梢，α -突触核蛋白经历了一个膜结合和解离的循环。采用α -突触核蛋白结合试验筛选参与α -突触核蛋白膜相互作用的囊泡蛋白，结果表明，针对ras相关GTPase Rab3a及其伴侣RabGDI的抗体可消除α -突触核蛋白膜结合。生化分析，包括密度梯度沉降和共免疫沉淀，表明α -突触核蛋白与膜相关的gtp结合的Rab3a相互作用，但不与细胞质GDP-Rab3a相互作用。通过表达gtpase缺陷的Rab3a突变体、无法从膜上回收Rab3a的显性负的gdp解离抑制剂突变体、以及已知能抑制Rab3a从膜上解离的Hsp90抑制剂、radicicol和geldanamycin，诱导了膜结合α -突触核蛋白的积累。因此，所有抑制Rab3a循环的处理也增加了细胞膜上α -突触核蛋白的封存。我们的研究结果表明，膜结合的GTP-Rab3a稳定突触囊泡上的α -突触核蛋白，而GDP解离抑制剂。控制rab3a膜解离的Hsp90复合体也在突触活动期间调节α -突触核蛋白解离。
alpha-Synuclein is an abundant presynaptic protein and a primary component of Lewy bodies in Parkinson disease. Although its pathogenic role remains unclear, in healthy nerve terminals alpha-synuclein undergoes a cycle of membrane binding and dissociation. An alpha-synuclein binding assay was used to screen for vesicle proteins involved in alpha-synuclein membrane interactions and showed that antibodies directed to the Ras-related GTPase Rab3a and its chaperone RabGDI abrogated alpha-synuclein membrane binding. Biochemical analyses, including density gradient sedimentation and co-immunoprecipitation, suggested that alpha-synuclein interacts with membrane-associated GTP-bound Rab3a but not to cytosolic GDP-Rab3a. Accumulation of membrane-bound alpha-synuclein was induced by the expression of a GTPase-deficient Rab3a mutant, by a dominant-negative GDP-dissociation inhibitor mutant unable to recycle Rab3a off membranes, and by Hsp90 inhibitors, radicicol and geldanamycin, which are known to inhibit Rab3a dissociation from membranes. Thus, all treatments that inhibited Rab3a recycling also increased alpha-synuclein sequestration on intracellular membranes. Our results suggest that membrane-bound GTP-Rab3a stabilizes alpha-synuclein on synaptic vesicles and that the GDP dissociation inhibitor.Hsp90 complex that controls Rab3 a membrane dissociation also regulates alpha-synuclein dissociation during synaptic activity.