Relationship between alpha synuclein phosphorylation, proteasomal inhibition and cell death: relevance to Parkinson's disease pathogenesis
Relationship between alpha synuclein phosphorylation, proteasomal inhibition and cell death: relevance to Parkinson's disease pathogenesis
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DOI：
10.1111/j.1471-4159.2009.06191.x
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发表时间：
2009-08-01
影响因子：
4.7
通讯作者：
Cooper, J. Mark
中科院分区：
文献类型：
--
作者：
Chau, Kai-Yin;Ching, Hey Long;Cooper, J. Mark
α-突触核蛋白可以在丝氨酸129（P-S129）处磷酸化，并且路易体中高度磷酸化的α-突触核蛋白的存在表明其磷酸化状态的变化具有重要的病理作用。我们证明了负责α-突触核蛋白S129磷酸化的激酶在SH-SY 5 Y细胞中是组成性活性的，并且涉及酪蛋白激酶2活性。增加氧化应激或蛋白酶体抑制引起P-S129 α-突触核蛋白水平的显着升高。在这些条件下，在十二烷基硫酸钠裂解物和Triton提取物中均发现P-S129 α-突触核蛋白的类似增加，表明磷酸化蛋白是可溶的并且不导致聚集。S129磷酸化的速率响应于蛋白酶体抑制而增加，表明相关激酶的活性更高。表达磷酸化模拟物S129 D α-突触核蛋白的细胞增加了细胞死亡并增强了对环氧霉素暴露的敏感性。蛋白酶体抑制显著降低S129 D α-突触核蛋白周转，表明蛋白酶体抑制通过激酶活性增加和蛋白周转减少导致P-S129 α-突触核蛋白积累，从而增加细胞死亡。我们的结论是，S129磷酸化是有毒的多巴胺能细胞和S129磷酸化蛋白的水平和其毒性增加与蛋白酶体抑制强调这些途径的相互依赖性在帕金森氏病的发病机制。
Alpha synuclein can be phosphorylated at serine129 (P-S129), and the presence of highly phosphorylated alpha-synuclein in Lewy bodies suggests changes to its phosphorylation status has an important pathological role. We demonstrate that the kinase(s) responsible for alpha-synuclein S129 phosphorylation is constitutively active in SH-SY5Y cells and involves casein kinase 2 activity. Increased oxidative stress or proteasomal inhibition caused significant elevation of P-S129 alpha-synuclein levels. Under these conditions, similar increases in P-S129 alpha-synuclein were found in both sodium dodecyl sulphate lysates and Triton extracts indicating the phosphorylated protein was soluble and did not lead to aggregation. The rate of S129 phosphorylation was increased in response to proteasomal inhibition indicating a higher activity of the relevant kinase. Cells expressing the phosphorylation mimic, S129D alpha-synuclein increased cell death and enhanced sensitivity to epoxomycin exposure. Proteasomal inhibition markedly decreased S129D alpha-synuclein turnover suggesting proteasomal inhibition leads to the accumulation of P-S129 alpha-synuclein through an increase in the kinase activity and a decrease in protein turnover resulting in increased cell death. We conclude that S129 phosphorylation is toxic to dopaminergic cells and both the levels of S129 phosphorylated protein and its toxicity are increased with proteasomal inhibition emphasising the interdependence of these pathways in Parkinson's disease pathogenesis.