INVESTIGATORS: Geoff Stilwell, Rhode Island College
THEME: Neuroscience

ABSTRACT: Amyotrophic Lateral Sclerosis (ALS) is characterized by progressive motor neuron (MN) degeneration, muscle weakness and death within 3-5 after diagnosis. Mutations in superoxide dismutase 1 (sod1) cause ALS and approximately 170 different mutations in this gene have been documented in patients to date. Irrespective of which mutation is present, SOD1 mutant protein forms aggregates. Aggregates are the presumptive toxic species which produce MN cell death based on correlations between their presence in MNs and disease symptoms. In fact, mutations in other genes which cause ALS also produce protein aggregates leading to the unifying theme that aggregated protein causes disease. However, the location and composition of protein aggregates are not consistent across all forms of ALS; nor are all downstream events conserved. Therefore, exactly how aggregates produce MN death is unclear. Some data suggest soluble (fibrillar forms representing pre-aggregated states) may be the toxic species of proteins. To help dissect the relationship between formation of aggregates and ALS, we will characterize aggregates in a Drosophila model of ALS. We created a series of mono-specific polyclonal antibodies which recognize short peptide motifs present in Drosophila SOD1. Antibody SOD1120-142 recognizes soluble, properly folded dimeric protein while antibody SOD156-71 recognizes aggregates due to an antigenic motif that becomes exposed upon aggregate assembly. Our preliminary data show dsod1 mutant lines produce aggregated SOD1, which are visualized as puncta. Using these antibodies, we will characterize the dynamics of aggregate formation by immunocytochemistry and protein gels. We proposed to: 1) Determine the extent and subcellular localization of aggregates within different classes of neurons in larvae and adults; and 2) Determine whether SOD1 aggregates are present in other models of ALS including C9orf72 mutants and TDP-43 mutants.

RELEVANCE: This proposal will characterize the dynamics of aggregate formation, a hallmark feature of ALS thought to contribute to motor neuron death. The project will leverage a fruitful and long-standing collaboration with Brown University and will provide undergraduates at Rhode Island College the opportunity to engage in substantive translational research.