Selective nitration of mitochondrial complex I by peroxynitrite: involvement in mitochondria dysfunction and cell death of dopaminergic SH-SY5Y cells

3-Nitrotyrosine (3-NT) is a specific marker of protein nitration by peroxynitrite (ONOO-) produced from nitric oxide and superoxide. Increase in 3-NT containing protein (3-NT protein) was reported in brains from patients with some neurodegenerative disorders and aging. In this paper, intracellular localization of 3-NT protein was examined in dopaminergic SH-SY5Y cells using the selective antibody against protein-bound 3-NT. 3-NT protein was detected in plasma membrane/nucleus and mitochondria fractions, and interestingly in polypeptide composition of mitochondrial complex I. ONOO--generating SIN-1 induced apoptotic cell death with concomitant increase in 3-NT protein and reduction in mitochondrial ATP synthesis. In addition, an inhibitor of proteasomes, carbobenzoxy-L-isoleucyl-gamma-t-butyl-L-glutamyl-L-alanyl-L-leucinal, enhanced the effects of ONOO-. These results suggest that ONOO- may induce mitochondrial dysfunction and cell death in neurons through nitration of mitochondrial complex I subunits.