α-Synuclein arginylation in the human brain
Jun Zhao, Buyan Pan, Marie E. Fina, Yun Huang, Marie Shimogawa, Kelvin C. Luk, Elizabeth Rhoades, E. James Petersson, Dawei Dong, Anna Kashina
Abstract
BACKGROUND: Alpha-synuclein (α-syn) exhibits pathological misfolding in many human neurodegenerative disorders. We previously showed that α-syn is arginylated in the mouse brain and that lack of arginylation leads to neurodegeneration in mice. METHODS: Here, we tested α-syn arginylation in human brain pathology using newly derived antibodies in combination with Western blotting, biochemical assays, and experiments in live neurons. RESULTS: We found that α-syn was arginylated in the human brain on E46 and E83, two sites previously implicated in α-syn pathology and familial cases of Parkinson's disease. The levels of arginylation in different brain samples ranged between ~ 3% and ~ 50% of the total α-syn pool, and this arginylation nearly exclusively concentrated in the subcellular α-syn fraction that sedimented at low centrifugation speeds and appeared to be simultaneously targeted by multiple posttranslational modifications. Arginylated α-syn was less susceptible to S129 phosphorylation and pathological aggregation in neurons. The arginylation level inversely correlated with the overall α-syn levels and with patient age, suggesting a possible causal relationship between arginylation decline and α-syn-dependent neuropathology. CONCLUSION: We propose that α-syn arginylation constitutes a potential neuroprotective mechanism that prevents its abnormal accumulation during neurodegeneration and aging in the human brain.