S-nitrosoglutathione potentiates protein S-nitrosation under oxidative stress, a potential improvement of NO storage into smooth muscle cells

Cardiovascular diseases are associated with oxidative stress and reduced nitric oxide (NO) bioavailability. The ability of NO donors like S-nitrosoglutathione (GSNO) to regulate NO bioavailability under oxidative stress is poorly studied. Here, we monitored protein S-nitrosation (Pr-SNO), a post-translational protein modification in smooth muscle cells exposed to GSNO under oxidative stress. Intracellular thiol redox status in relation with the extent and distribution of GSNO-induced intracellular Pr-SNO (LC-MALDI MS) were assessed. The role of the gammaglutamyl transferase (GGT), a redox enzyme metabolizing GSNO, in Pr-SNO formation was also studied. GSNO prevented the oxidation of proteins SH groups. Concomitantly, a 2-fold increase of GSNO-dependent Pr-SNO formation still depending on GGT activity was observed. Mass spectrometry identified 51 proteins S-nitrosated by GSNO under oxidative stress (vs 32 in basal condition), including a higher number of cytoskeletal proteins (17 vs 8 in basal condition) related to cell morphogenesis and movement. Furthermore, additional proteins belong to cell adhesion and protein trafficking were S-nitrosated under oxidative stress. Oxidative stress modifies the extent and distribution of GSNO induced Pr-SNO formation, a NO storage form in tissue. Further studies will likely elucidate the pathophysiological significance of these observations.