The Protein Oxidation Repair Enzyme Methionine Sulfoxide Reductase A Modulates Aβ Aggregation and Toxicity In Vivo

Aims: To examine the role of the enzyme methionine sulfoxide reductase A-1 (MSRA-1) in amyloid-beta peptide (A beta)-peptide aggregation and toxicity in vivo, using a Caenorhabditis elegans model of the human amyloidogenic disease inclusion body myositis. Results: MSRA-1 specifically reduces oxidized methionines in proteins. Therefore, a deletion of the msra-1 gene was introduced into transgenic C. elegans worms that express the A beta-peptide in muscle cells to prevent the reduction of oxidized methionines in proteins. In a constitutive transgenic A beta strain that lacks MSRA-1, the number of amyloid aggregates decreases while the number of oligomeric A beta species increases. These results correlate with enhanced synaptic dysfunction and mislocalization of the nicotinic acetylcholine receptor ACR-16 at the neuromuscular junction (NMJ). Innovation: This approach aims at modulating the oxidation of A beta in vivo indirectly by dismantling the methionine sulfoxide repair system. The evidence presented here shows that the absence of MSRA-1 influences A beta aggregation and aggravates locomotor behavior and NMJ dysfunction. The results suggest that therapies which boost the activity of the Msr system could have a beneficial effect in managing amyloidogenic pathologies. Conclusion: The absence of MSRA-1 modulates A beta-peptide aggregation and increments its deleterious effects in vivo. Antioxid. Redox Signal. 22, 48-62.