Alpha-Synuclein-Metal Complexes and Oxidative Stress in Parkinson's Disease

描述（由申请人提供）：帕金森病（PD）是一种进行性神经退行性疾病，主要表现为患病大脑中多巴胺能神经元的逐渐丧失。退行性多巴胺能细胞（路易小体）的主要包涵体含有a-突触核蛋白（a-syn）蛋白的聚集体。PD患者多巴胺能细胞胞浆中Fe（III）浓度和脑脊液中Cu（II）含量均升高。氧化应激假说认为，a-syn和氧化还原活性金属离子之间形成的复合物可以对神经元细胞施加氧化应激，这一假说引起了广泛的关注。该提案的广泛、长期目标是使各种氧化还原反应在氧化应激和损伤的发展中合理化，这些反应涉及a-同形金属配合物和胞质物质（如多巴胺、谷胱甘肽和抗坏血酸）。这项研究背后的动机是，目前氧化应激假说的不一致主要源于缺乏对a-syn-金属配合物的氧化还原电位的了解，以及对产生活性氧（ROS）的反应的详细了解。具体目标包括：(1)研究Fe（III）和Cu（II）与野生型和突变型a-syn分子的结合以及由此产生的复合物的氧化还原特性，(2)探测涉及这些a-syn金属复合物的ros生成反应的动力学，以及(3)检查a-syn在Fe（III）或Cu（II）存在下的聚集行为并评估由此产生的聚集体的神经毒性。还将进行外源物质（如黄酮类抗氧化剂或除草剂等PD危险因素）存在下a-syn-金属配合物或含金属的a-syn聚集体的动力学研究。各种分析技术（如核磁共振、EPR、伏安法、荧光和吸附光谱）将被用于研究结合和氧化还原反应，而原子力显微镜、圆二色性和动态光散射将被用于跟踪聚集过程。

DESCRIPTION (provided by applicant): Parkinson's disease (PD) is a progressive neurodegenerative disorder underscored by the gradual loss of dopaminergic neurons in disease-inflicted brains. The major inclusion in degenerating dopaminergic cells (Lewy bodies) contains aggregates of the a-synuclein (a-syn) protein. The Fe(III) concentration in the cytoplasm of dopaminergic cells and Cu(II) content in cerebral spinal fluid of PD patients are both elevated. The oxidative stress hypothesis, which contends that complexes formed between a-syn and redox active metal ions could impose oxidative stress on neuronal cells, has gained widespread attention. The broad, long-term objective of this proposal is to rationalize the various redox reactions involving a-syn-metal complexes and cytosolic species (e.g., dopamine, glutathione, and ascorbic acid) in the development of oxidative stress and damage. The motivation behind the proposed study is that the inconsistencies in the current oxidative stress hypothesis stem largely from the lack of knowledge of the redox potentials of the a-syn-metal complexes and a detailed understanding of the reactions that produce reactive oxygen species (ROS). The specific aims include (1) studying the binding of Fe(III) and Cu(II) to wild-type and mutant a-syn molecules and the redox properties of the resultant complexes, (2) probing the kinetics of the ROS-producing reactions that involve these a-syn-metal complexes, and (3) examining the aggregation behaviors of a-syn in the presence of Fe(III) or Cu(II) and evaluating the neurotoxicity of the resultant aggregates. The kinetic studies of the a-syn-metal complexes or metal-containing a-syn aggregates in the presence of exogenous species (e.g., antioxidants such as flavonoids or PD risk factors such as herbicides) will also be conducted. A variety of analytical techniques (e.g., NMR, EPR, voltammetry, fluorescence, and adsorption spectroscopy) will be used to investigate the binding and redox reactions, whereas atomic force microscopy, circular dichroism, and dynamic light scattering will be employed to follow the aggregation processes. PUBLIC HEALTH RELEVANCE: The study will provide insight into the possible roles played by Fe(III), Cu(II), and a-synuclein in the etiology of Parkinson's disease (PD). The results are expected to lead to a better understanding of the associated molecular mechanisms, the modification of which might prevent or alleviate the neuropathological effects of PD. Furthermore, given the variety of techniques proposed and the interdisciplinary nature of this high-impact research, the work will play a significant part in training the next generation of researchers at a minority-serving institution.