Up-regulation of protein tyrosine nitration in methamphetamine-induced neurotoxicity through DDAH/ADMA/NOS pathway

• Acute METH exposure results in over-expression of DDAH1 mRNA and protein.
• METH activates DDAH1/ADMA/NOS pathway both in vivo and in vitro.
• Excess NO leads to increased expressions of nitrated proteins.
• The nitroproteins are relevant to Cdk5, cytoskeletal structure and ribosomes.
• DDAH1 inhibitor L-257 protects against METH-induced neurotoxicity.

Protein tyrosine nitration is an important post-translational modification mediated by nitric oxide (NO) associated oxidative stress, occurring in a variety of neurodegenerative diseases. In our previous study, an elevated level of dimethylarginine dimethylaminohydrolase 1 (DDAH1) protein was observed in different brain regions of acute methamphetamine (METH) treated rats, indicating the possibility of an enhanced expression of protein nitration that is mediated by excess NO through the DDAH1/ADMA (Asymmetric Dimethylated l-arginine)/NOS (Nitric Oxide Synthase) pathway. In the present study, proteomic methods, including stable isotope labeling with amino acids in cell culture (SILAC) and two dimensional electrophoresis, were used to determine the relationship between protein nitration and METH induced neurotoxicity in acute METH treated rats and PC12 cells. We found that acute METH administration evokes a positive activation of DDAH1/ADMA/NOS pathway and results in an over-production of NO in different brain regions of rat and PC12 cells, whereas the whole signaling could be repressed by DDAH1 inhibitor Nω-(2-methoxyethyl)-arginine (l-257). In addition, enhanced expressions of 3 nitroproteins were identified in rat striatum and increased levels of 27 nitroproteins were observed in PC12 cells. These nitrated proteins are key factors for Cdk5 activation, cytoskeletal structure, ribosomes function, etc. l-257 also displayed significant protective effects against METH-induced protein nitration, apoptosis and cell death. The overall results illustrate that protein nitration plays a significant role in the acute METH induced neurotoxicity via the activation of DDAH1/ADMA/NOS pathway.