Mitochondrial import and accumulation of α-synuclein impair complex I in human dopaminergic neuronal cultures and Parkinson disease brain
Mitochondrial import and accumulation of α-synuclein impair complex I in human dopaminergic neuronal cultures and Parkinson disease brain
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DOI：
10.1074/jbc.m710012200
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发表时间：
2008-04-04
影响因子：
4.8
通讯作者：
Anandatheerthavarada, Hindupur K.
中科院分区：
文献类型：
--
作者：
Devi, Latha;Raghavendran, Vijayendran;Anandatheerthavarada, Hindupur K.
α -突触核蛋白，一种与帕金森病（PD）发病机制有关的蛋白质，被认为影响线粒体功能，尽管其作用机制尚不清楚。本研究发现，人α -synuclein的n端32个氨基酸中含有线粒体靶向信号，这对α -synuclein的线粒体靶向具有重要意义。线粒体输入的α -突触核蛋白主要与内膜相关。野生型α -突触核蛋白在人多巴胺能神经元线粒体中的积累导致线粒体复合体I活性降低和活性氧的产生增加。然而，与野生型α -突触核蛋白相比，这些缺陷在表达A53T突变的家族性α -突触核蛋白的多巴胺能神经元中发生的时间点更早。重要的是，缺乏线粒体靶向信号的α -突触核蛋白无法靶向线粒体，对复合物I功能没有可检测到的影响。利用死后迟发性帕金森病和正常人大脑的黑质、纹状体和小脑线粒体研究了这些结果与帕金森病的相关性。结果显示，在正常受试者的三个脑区线粒体中均存在类似于14- kDa α -突触核蛋白的组成。PD易感的黑质和纹状体线粒体中α -突触核蛋白显著积累，复合体I活性降低，小脑中没有。利用蓝色天然凝胶电泳和免疫捕获技术对PD脑组织线粒体和表达多巴胺能神经元培养的α -突触核蛋白进行分析，发现α -突触核蛋白与复合体I存在关联。这些结果表明，线粒体积累的α -突触核蛋白可能与复合体I相互作用并干扰其功能。
alpha-Synuclein, a protein implicated in the pathogenesis of Parkinson disease ( PD), is thought to affect mitochondrial functions, although the mechanisms of its action remain unclear. In this study we show that the N-terminal 32 amino acids of human alpha-synuclein contain cryptic mitochondrial targeting signal, which is important for mitochondrial targeting of alpha-synuclein. Mitochondrial imported alpha-synuclein is predominantly associated with the inner membrane. Accumulation of wild-type alpha-synuclein in the mitochondria of human dopaminergic neurons caused reduced mitochondrial complex I activity and increased production of reactive oxygen species. However, these defects occurred at an early time point in dopaminergic neurons expressing familial alpha-synuclein with A53T mutation as compared with wild-type alpha-synuclein. Importantly, alpha-synuclein that lacks mitochondrial targeting signal failed to target to the mitochondria and showed no detectable effect on complex I function. The PD relevance of these results was investigated using mitochondria of substantia nigra, striatum, and cerebellum of postmortem late-onset PD and normal human brains. Results showed the constitutive presence of similar to 14- kDa alpha-synuclein in the mitochondria of all three brain regions of normal subjects. Mitochondria of PD-vulnerable substantia nigra and striatum but not cerebellum from PD subjects showed significant accumulation of alpha-synuclein and decreased complex I activity. Analysis of mitochondria from PD brain and alpha-synuclein expressing dopaminergic neuronal cultures using blue native gel electrophoresis and immunocapture technique showed the association of alpha-synuclein with complex I. These results provide evidence that mitochondrial accumulated alpha-synuclein may interact with complex I and interfere with its functions.