NEUROFILAMENT INVOLVEMENT IN LEWY BODY DISORDERS

Lewy bodies are filamentous inclusions that occur in selected brainstem, limbic, and neocortical neurons in several disabling and dementing neurodegenerative diseases, including Parkinson's disease, diffuse Lewy body disease, and a subset of Alzheimer's disease. Neither the pathogenic events leading to Lewy body formation, nor the composition of Lewy bodies are known. The long-term objectives of this research are to identify the key components of Lewy bodies, to characterize both immediate pathogenic events leading to the formation of Lewy bodies as well as earlier or more primary pathological events and to clarify the relationship between Alzheimer's disease and Lewy body associated disorders. In this proposal a limited set of goals will be pursued that focus on the role of the neurofilament triplet proteins in the formation of Lewy body filaments and on their role as a target in the pathogenesis of these disorders. Neurofilament proteins are the focus of the application because they are currently the most convincing and consistent of the potential Lewy body filament molecules. The overall hypothesis of this application is that neurofilament metabolism is disrupted in Lewy body associated disorders such as Parkinson's disease, diffuse Lewy body disease, and subsets of Alzheimer's disease. The specific aims center on neurofilament involvement in these Lewy body associated diseases. These aims incorporate analysis of neurofilament metabolism in vulnerable neuron populations at the level of mRNA and protein expression, including post-translational modifications to neurofilament subunits. To accomplish this epitope mapping will be employed with a unique library of antibodies combined with confocal microscopy, quantitative in situ hybridization and ribonuclease protection assays. The specific aims also incorporate the isolation and characterization of Lewy bodies in order to directly determine if neurofilament subunits are components and if they are post-translationally modified. Novel strategies will be used for the isolation of Lewy bodies (affinity based) and the production of Lewy body specific antibodies (tolerization based). Additionally, this information will be compared between cortical and subcortical neuronal populations as well as across disease categories. While neurofilaments have been strongly implicated in the formation of Lewy body filaments, and alterations in neurofilament processing are suspected in Lewy body associated disorders, the question of their involvement has not been settled. The intention of this proposal is to move towards a clearer assessment of the role of neurofilaments in these disorders.