alpha-突触核蛋白通过PP2A调节TH磷酸化的结构学机理

项目名称： alpha-突触核蛋白通过PP2A调节TH磷酸化的结构学机理

项目编号： No.31271136

项目类型： 面上项目

立项/批准年度： 2013

项目学科： 生物科学

项目作者： 张建亮

作者单位： 首都医科大学

项目金额： 76万元

中文摘要： 帕金森病是仅次于阿兹海默症的第二大神经退行性疾病。黑质纹状体多巴胺递质水平低下是该病运动功能异常的主要原因。酪氨酸羟化酶(TH)是儿茶酚胺类物质合成限速酶,磷酸化水平决定其多巴胺合成的活性。本组及他人都证明蛋白磷酸酶2A(PP2A)能够使TH去磷酸化从而抑制它的活性,而且α-突触核蛋白（α-syn）能够上调PP2A的去磷酸化活性从而降低多巴胺的生物合成。但是这种调控背后的分子结构学机理并不清楚。本研究试图采用定点突变，凝胶过滤及Pull-down等方法，对PP2A，TH以及α-syn进行结构-功能分析，研究TH与PP2A的结合方式，找出在PP2A上TH的结合位点；同时揭示α-syn和PP2A结合作用方式，洞察二者起结合作用的结构域及具体的氨基酸位点。最终明确α-syn通过上调PP2A活性而使TH磷酸化水平降低的结构学机理，为深入理解帕金森病的发病机制和开发潜在药物靶点提供新思路。

中文关键词： 帕金森病；alpha-突触核蛋白；蛋白磷酸酶2A；酪氨酸羟化酶；

英文摘要： Parkinson's disease is the second most common neurodegenerative disorder after Alzheimer's disease, and affects 2% of people over the age of 60. The main cause of the movement disorder is the dopamine depletion, which results from greatly reduced activity of dopamine-secreting cells caused by cell death in the pars compacta region of the substantia nigra. Tyrosine hydroxylase (TH), the rate-limiting enzyme in catecholamine synthesis, is stimulated by N-terminal phosphorylation, which determines the dopamine biosynthesis activity. We and others have previously demonstrated that tyrosine hydroxylase is almost exclusively dephosphorylated and consequently inhibited by protein serine/threonine phosphatase 2A (PP2A), and the alpha-synuclein(α-syn) may potentiate PP2A's ability of dephosphorylation, resulting more inhibition of TH and less dopamine biosynthesis. However, now the structural mechanism underlying the α-syn-and-PP2A-mediated TH phosphorylation modulation is still elusive. In this project, we plan to employ the site-directed mutagenesis, gel-filtration, pull-down, and so on, to study the structure-function relationships between the PP2A, TH and α-syn, to identify the binding sites and even finally the exact corresponding residues in the respective protein. Through this approach we may get novel insight int

英文关键词： Parkinson's disease；alpha-synuclein；protein phosphatase 2A；tyrosine hydroxylase；