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.