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 i nclude (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.
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.
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