METALLATION LEVELS OF PROTEIN AGGREGATES FORMED IN AMYOTROPHIC LATERAL SCLEROSIS

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Amyotrophic lateral sclerosis (ALS) is a debilitating neurodegenerative disease characterized by loss of motor neurons leading to paralysis and ultimately death. Familial ALS is caused by mutations in the copper- and zinc-containing enzyme superoxide dismutase (SOD1), a vital antioxidant protein. The spinal cords of patients contain abundant protein-rich aggregates, suggesting that SOD1-linked ALS, like other neurodegenerative diseases, is a proteinmisfolding disease. Recently it was shown that unmodified, full-length SOD1 is the principal protein in these aggregates, whose appearance correlates with the onset of symptoms. It is currently not known whether the SOD1 protein in the aggregates retains its Cu/Zn metallation state or whether loss of the metal ions results in protein misfolding. As SOD1 relies on Cu and Zn for its activity and stability, it is an important component of the disease to examine. In this study, we will examine the spinal cords of ALS mice that produce a range of SOD1 mutations ¿ some mutations that bind metal in vitro and others that do not. The transgenic mice that overexpress mutant forms of SOD1 develop aggregates in the spinal cord and disease pathology including paralysis. Using the XRF microprobe, we will determine (1) the Cu/Zn content within the aggregates, (2) the Cu oxidation state within the aggregates, and (3) the Cu/Zn content in unaffected neurons. These data will be superimposed and correlated with FTIR microscopy images (collected at the NSLS) that provide a distribution of aggregated beta sheet protein and lipid peroxidation. Determining the link between protein metallation state, aggregate formation, and neuron cell death is critical for understanding ALS pathology and could subsequently lead to developing a drug to treat or cure ALS.