电化学活性的alpha-突触核蛋白金属化合物在帕金森病中的作用机制研究

Parkinson's disease (PD) is the second most common neurodegenerative disease, characterized by a progressive loss of dopaminergic neurons in the substantia nigra parscompacta and by the presence of Lewy bodies which is largely constituted by the small protein α-synuclein (α-syn)). A popular hypothesis for the PD etiology is oxidative stress, an imbalance between the production of reactive oxygen species (ROS) and a biological system's ability to readily detoxify these reactive intermediates. Numerous research works have proven that both metal ions and α-syn are highly involved in the neurodegenerative process. Metal ions are generally believed to exert oxidative disturbances by generating ROS via the Fenton reaction, whereas the contribution of the aberrant binding of the redox-active transition metals iron and copper to α-syn remains debatable to PD pathogenesis..In this proposal, the central theme is the study of redox reactions involving complexes formed between α-syn and Fe(III), Fe(II), or Cu(II). The implication of these redox reactions in PD neuropathology will be extrapolated. Specifically, redox potentials of α-syn-Fe(III), α-syn-Fe(II), and α-syn-Cu(II) complexes will be compared to those of complexes formed between α-syn peptide segments and the corresponding metal ions. The binding sites and the binding constants of α-syn to Fe(III), Fe(II) and Cu(II) will be confirmed. Kinetic studies will be performed on mixtures of α-syn-Fe(III) and a range of cellular species under aerobic and anaerobic conditions to investigate the viability of α-syn-metal-catalyzed oxidation of cellular species via a ternary complex intermediate. A major emphasis will be placed on the understanding of the role of α-syn in the iron-catalyzed dopaime (DA) oxidation reaction. The aggregation of α-syn in the presence of Cu(II), Fe(II), or Fe(III) will also be investigated to gain insight into the interplay between metal-induced aggregation and the role of metal-containing aggregates in oxidative stress. Finally, cytotoxicity of the metal-containing α-syn oligomers/aggregates and the metal complexes of α-syn will be studied. We envision that a comprehensive description about the fundamental aspect of redox reactions involving α-syn, redox metal ions, oxygen, and other cellular species, as well as the relative neurotoxicity of the various species and reactions, will evolve from our project. Such information will consolidate the understanding of the redox properties of amyloidogenic proteins/peptides and their involvements in oxidative stress in PD. It will also provide insight into animal model studies and clinical assays.

电化学活性的α-突触核蛋白金属化合物(α-syn-metal）通过触发氧化应激导致多巴胺能神经细胞死亡，这可能是帕金森病的主要病因之一。但是，目前关于α-syn金属结合位点的研究结果存在诸多矛盾、α-syn-metal触发氧化应激的分子机制尚不明确。本项目针对上述问题，拟首先设计合成不同的α-syn片段，采用光谱实验与理论计算相结合的方法，确定α-syn对铁、铜等金属离子的特异性结合位点和结合常数；在此基础上，系统研究多种形态α-syn-metal的氧化还原特性，以及α-syn-metal与影响氧化应激的主要因素如氧、多巴胺、胞内抗氧化剂等的相互作用机制，构建α-syn-metal氧化细胞物种的反应网络模型；通过评估α-syn-metal的细胞毒性及其影响因素，建立α-syn-metal触发氧化应激、诱导多巴胺能神经细胞死亡的分子机制，为帕金森病病理研究和药物开发提供理论指导。

电化学活性的淀粉蛋白/金属化合物(α-syn-metal和Aβ-metal）通过触发氧化应激导致神经细胞死亡，这可能是帕金森病和老年痴呆的主要病因之一。但是，目前关于α-syn（Aβ）金属结合位点的研究结果存在诸多矛盾、α-syn-metal（Aβ-metal）触发氧化应激的分子机制尚不明确。针对上述问题，本项目首先建立了几种高灵敏的淀α-syn和Aβ检测方法，实现了淀粉蛋白在溶液和仿生膜上跨膜行为的准确监测。在此基础上，采用光谱实验与理论计算相结合的方法，确定了α-syn和Aβ对铁、铜等金属离子的特异性结合位点和结合常数，以及相关蛋白金属硫蛋白2的铅合结合位点；系统研究淀粉蛋白/金属复合物单体、寡聚体和纤维等形态的氧化还原特性，以及影响氧化应激的主要因素多巴胺、NE、以及胞内抗氧化剂金属硫蛋白3等的相互作用机制；通过评估细胞毒性，建立了α-syn-metal和Aβ-metal触发氧化应激、诱导神经细胞死亡的分子机制，为帕金森病和老年痴呆病理研究和药物开发提供理论了指导。