Copper Reduces Aβ Oligomeric Species and Ameliorates Neuromuscular Synaptic Defects in a C. elegans Model of Inclusion Body Myositis

Alzheimer's disease and inclusion body myositis (IBM) are disorders frequently found in the elderly and characterized by the presence of amyloid-beta peptide (A beta) aggregates. We used Caenorhabditis elegans that express A beta in muscle cells as a model of IBM, with the aim of analyzing A beta-induced muscle pathology and evaluating the consequences of modulating A beta aggregation. First, we tested whether the altered motility we observed in the A beta transgenic strain could be the result of a compromised neuromuscular synapse. Our pharmacological analyses show that synaptic transmission is defective in our model and suggest a specific defect on nicotine-sensitive acetylcholine receptors (AChRs). Through GFP-coupled protein visualization, we found that synaptic dysfunction correlates with mislocalization of ACR-16, the AChR subunit essential for nicotine-triggered currents. Histological and biochemical analysis allowed us to determine that copper treatment increases the amyloid deposits and decreases A beta oligomers in this model. Furthermore, copper treatment improves motility, ACR-16 localization, and synaptic function and delays A beta-induced paralysis. Our results indicate that copper modulates A beta-induced pathology and suggest that A beta oligomers are triggering neuromuscular dysfunction. Our findings emphasize the importance of neuromuscular synaptic dysfunction and the relevance of modulating the amyloidogenic component as an alternative therapeutic approach for this debilitating disease.