Department of Biology and Biochemistry, University of Bath, Bath, UK.
J Neurochem. 2010 May;113(3):704-14. doi: 10.1111/j.1471-4159.2010.06638.x. Epub 2010 Feb 5.
Alpha-synuclein is a natively unfolded protein that aggregates and forms inclusions that are associated with a range of diseases that include Parkinson's Disease and Dementia with Lewy Bodies. The mechanism behind the formation of these inclusions and their possible role in disease remains unclear. Alpha-synuclein has also been shown to bind metals including copper and iron. We used a cell culture model of alpha-synuclein aggregation to examine the relationship between metals and formation of aggregates of the protein. While the levels of iron appear to have no role in aggregate formation or localisation of the protein in cells, copper appears to be important for both aggregation and cellular localisation of alpha-synuclein. Reduction in cellular copper resulted in a great decrease in aggregate formation both in terms of large aggregates visible in cells and oligomers observed in western blot analysis of cell extracts. Reduction in copper also resulted in a change in localisation of the protein which became more intensely localised to the plasma membrane in medium with low copper. These changes were reversed when copper was restored to the cells. Mutants of the copper binding domains altered the response to copper. Deletion of either the N- or C-termini resulted in a loss of aggregation while deletion of the C-termini also resulted in a loss of membrane association. Increased expression of alpha-synuclein also increased cell sensitivity to the toxicity of copper. These results suggest that the potential pathological role of alpha-synuclein aggregates is dependent upon the copper binding capacity of the protein.
α-突触核蛋白是一种天然无规则的蛋白质，会聚集形成包含物，与一系列疾病有关，包括帕金森病和路易体痴呆症。这些包含物形成的机制及其在疾病中的可能作用尚不清楚。α-突触核蛋白还被证明可以结合金属，包括铜和铁。我们使用α-突触核蛋白聚集的细胞培养模型来研究金属与蛋白质聚集体形成之间的关系。虽然铁的水平似乎在蛋白质聚集体的形成或细胞内定位中没有作用，但铜似乎对聚集和α-突触核蛋白的细胞内定位都很重要。细胞内铜的减少导致聚集体的形成大大减少，无论是在细胞中可见的大聚集体还是在细胞提取物的western blot 分析中观察到的寡聚体。铜的减少还导致蛋白质的定位发生变化，在低铜培养基中，蛋白质变得更强烈地定位在质膜上。当铜被恢复到细胞中时，这些变化就会逆转。铜结合结构域的突变改变了对铜的反应。N 或 C 末端的缺失导致聚集的丧失，而 C 末端的缺失也导致膜结合的丧失。α-突触核蛋白的过度表达也增加了细胞对铜毒性的敏感性。这些结果表明，α-突触核蛋白聚集体的潜在病理作用取决于蛋白质的铜结合能力。
