This is a proposal to determine if defects in mitochondrial oxidative phosphorylation may play a direct role in the etiology of Parkinson's disease and other movement disorders. The principal investigators hypothesize that these could be due to either inherited mutations in oxydative phosphorylation genes encoded on mitochondrial or nuclear DNA or due to somatic deletions in mitochondrial DNA. The principal investigators propose to examine oxidative phosphorylation function using both polarographic and biochemical activity assays in muscle biopsy specimens obtained from 170 patients with movement disorders. These will consist of 80 patients with Parkinson's disease, 20 with multiple system atrophy, 20 with progressive supranuclear palsy and 50 with dystonia. They also proposed to examine the brains of patients with movement disorders consisting of 10 Parkinson's disease patients, 6 with multiple system atrophy, 6 with progressive supranuclear palsy and 6 with dystonia. To determine whether mitochondrial DNA mutations are etiologic in the movement disorders patients will be stratified into 3 groups based on the results of testing for oxidative phosphorylation defects in both muscle mitochondria and in myoblast and lymphoblast cell lines. Group 1 will consist of patients who show defects both in muscle as well as in cell lines, group 2 will consist of patients showing defects in muscle but not in cell lines and Group 3 will consist of patients who do not show defects. The patients in group 1 will then undergo further studies to produce cybrid cells in which the mitochondria are fused into mitochondrial DNA deficient recipient cells. This will enable the principal investigators to determine if a mutation in the patients mitochondrial DNA causes any observed oxidative phosphorylation defects. The principal investigators will then screen for candidate mitochondrial DNA mutations. They will use several different techniques to perform this. This will include sequencing of the mitochondrial DNA. By using both the cybrid approach and determinations of mitochondrial DNA mutations they will determine whether mitochondrial DNA mutations cause specific movement disorders. They also propose to determine whether somatic mitochondrial DNA deletions contribute to the pathophysiology of movement disorders. They will assess the accumulation of somatic mitochondrial DNA deletions in brain and muscle tissue using dilution PCR quantitation, in situ hybridization and single cell PCR techniques to determine the level of somatic mitochondrial DNA deletions. They will also examine the functional consequences of somatic mitochondrial DNA deletions using both cytochrome C oxidase and succinate dehydrogenase histochemistry and in situ hybridization for messenger RNA encoded by both nuclear and mitochondrial oxidative phosphorylation genes.
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