The novel Parkinson's disease linked mutation G51D attenuates in vitro aggregation and membrane binding of α-synuclein, and enhances its secretion and nuclear localization in cells
The novel Parkinson's disease linked mutation G51D attenuates in vitro aggregation and membrane binding of α-synuclein, and enhances its secretion and nuclear localization in cells
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DOI：
10.1093/hmg/ddu165
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发表时间：
2014-09-01
影响因子：
3.5
通讯作者：
Lashuel, Hilal A.
中科院分区：
文献类型：
--
作者：
Fares, Mohamed-Bilal;Ait-Bouziad, Nadine;Lashuel, Hilal A.
最近在两个表现出帕金森病（PD）和多系统萎缩（MSA）特征的家族性病例中鉴定出α-突触核蛋白（α-Syn）基因“G51 D”的新突变。在这项研究中，我们探讨了这种新的突变对α-Syn的聚集，细胞和生物物理特性的影响，试图揭示这种突变如何有助于PD/MSA。我们的研究结果表明，G51 D突变显着减弱体外α-Syn聚集。此外，在SDS存在下，其破坏局部螺旋形成，降低与突变位点C-末端的脂质囊泡的结合，并在酸性囊泡存在下严重抑制螺旋折叠。当在酵母中表达时，α-Syn（G51 D）的行为与α-Syn（A30 P）相似，因为两者都表现出受损的膜结合，形成很少的内含物并且是无毒的。相比之下，在哺乳动物细胞以及原代神经元中观察到G51 D突变体的分泌和核水平增强，其中α-Syn（G51 D）在核区室中富集，在S129处过度磷酸化并加剧α-Syn诱导的线粒体片段化。最后，检查了alpha-Syn（G51 D）病例的死后人脑组织，发现仅部分与核膜标记物共定位，可能是由于死后组织延迟和固定。这些发现表明，PD连锁突变可能通过不同的机制引起神经退行性变，其中一些可能独立于α-Syn聚集。
A novel mutation in the alpha-Synuclein (alpha-Syn) gene "G51D" was recently identified in two familial cases exhibiting features of Parkinson's disease (PD) and multiple system atrophy (MSA). In this study, we explored the impact of this novel mutation on the aggregation, cellular and biophysical properties of alpha-Syn, in an attempt to unravel how this mutant contributes to PD/MSA. Our results show that the G51D mutation significantly attenuates alpha-Syn aggregation in vitro. Moreover, it disrupts local helix formation in the presence of SDS, decreases binding to lipid vesicles C-terminal to the site of mutation and severely inhibits helical folding in the presence of acidic vesicles. When expressed in yeast, alpha-Syn(G51D) behaves similarly to alpha-Syn(A30P), as both exhibit impaired membrane association, form few inclusions and are non-toxic. In contrast, enhanced secreted and nuclear levels of the G51D mutant were observed in mammalian cells, as well as in primary neurons, where alpha-Syn(G51D) was enriched in the nuclear compartment, was hyper-phosphorylated at S129 and exacerbated alpha-Syn-induced mitochondrial fragmentation. Finally, post-mortem human brain tissues of alpha-Syn(G51D) cases were examined, and revealed only partial colocalization with nuclear membrane markers, probably due to post-mortem tissue delay and fixation. These findings suggest that the PD-linked mutations may cause neurodegeneration via different mechanisms, some of which may be independent of alpha-Syn aggregation.