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

描述(申请人提供)：帕金森病(PD)是一种进行性神经退行性疾病，突出表现为疾病引起的大脑中多巴胺能神经元的逐渐丧失。退变的多巴胺能细胞(路易小体)的主要包涵体含有a-突触核蛋白(a-syn)的聚集体。PD患者多巴胺能细胞胞浆内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络合物可以对神经细胞施加氧化应激，这一假说已经得到了广泛的关注。这项提议的广泛、长期的目标是使涉及α-合金属络合物和胞浆物种(例如，多巴胺、谷胱甘肽和抗坏血酸)的各种氧化还原反应在氧化应激和损伤的发展中合理化。这项研究背后的动机是，目前氧化应激假说中的不一致很大程度上是由于缺乏对a-合成金属络合物的氧化还原电位的了解，以及对产生活性氧物种(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α-syn分子的结合及其形成的络合物的氧化还原性质；(2)探索涉及这些a-syn金属络合物的产生ROS的反应动力学；(3)研究a-syn在Fe(III)或Cu(II)存在下的聚集行为，并评价所生成的聚集体的神经毒性。还将进行在外源物种(例如，黄酮类等抗氧化剂或除草剂等帕金森病风险因素)存在下，a-合成金属络合物或含金属a-syn聚集体的动力学研究。将使用各种分析技术(例如，核磁共振、EPR、伏安、荧光和吸附光谱)来研究结合和氧化还原反应，而将使用原子力显微镜、圆二色谱和动态光散射来跟踪聚集过程。 公共卫生相关性：这项研究将深入了解铁(III)、铜(II)和α-突触核蛋白在帕金森病(PD)病因学中可能发挥的作用。这一结果有望更好地理解相关的分子机制，对其进行修饰可能会预防或减轻帕金森病的神经病理效应。此外，鉴于所提出的技术的多样性和这一高影响研究的跨学科性质，这项工作将在为少数群体服务的机构培训下一代研究人员方面发挥重要作用。

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.