Cardioprotection and mitochondrial S-nitrosation: Effects of S-nitroso-2-mercaptopropionyl glycine (SNO-MPG) in cardiac ischemia–reperfusion injury

Abstract

Mitochondrial dysfunction is a key pathologic event in cardiac ischemia-reperfusion (IR) injury, and protection of mitochondrial function is a potential mechanism underlying ischemic preconditioning (IPC). Acknowledging the role of nitric oxide (NO • ) in IPC, it was hypothesized that mitochondrial protein S-nitrosation may be a cardioprotective mechanism. The reagent S-nitroso-2-mercaptopropionyl-glycine (SNO-MPG) was therefore developed to enhance mitochondrial Snitrosation and elicit cardioprotection. Within cardiomyocytes, mitochondrial proteins were effectively S-nitrosated by SNO-MPG. Consistent with the recent discovery of mitochondrial complex I as an S-nitrosation target, SNO-MPG inhibited complex I activity and cardiomyocyte respiration. The latter effect was insensitive to the NO • scavenger c-PTIO, indicating no role for NO • -mediated complex IV inhibition. A cardioprotective role for reversible complex I inhibition has been proposed, and consistent with this SNO-MPG protected cardiomyocytes from simulated IR injury. Further supporting a cardioprotective role for endogenous mitochondrial S-nitrosothiols, patterns of protein S-nitrosation were similar in mitochondria isolated from Langendorff perfused hearts subjected to IPC, and mitochondria or cells treated with SNO-MPG. The functional recovery of perfused hearts from IR injury was also improved under conditions which stabilized endogenous S-nitrosothiols (i.e. dark), or by pre-ischemic administration of SNO-MPG. Mitochondria isolated from SNO-MPG-treated hearts at the end of ischemia exhibited improved Ca 2+ handling and lower ROS generation. Overall these data suggest that mitochondrial S-nitrosation and complex I inhibition constitute a protective signaling pathway that is amenable to pharmacologic augmentation.

A Proteomic Study of S-Nitrosylation in the Rat Cardiac Proteins in Vitro

“…It has been demonstrated that increased S-nitrosylation, triggered by IPC or low molecular weight S-nitrosothiols, exerts a critical role in cardiac protection against I/R injury. 7,8) Though available data point The cardiac extracts were incubated with GSNO at concentrations of 0, 100, 300 and 900 mM for 1 h, and then AK activity assayed after desalting. To some samples, DTT (1 mM) was added for 15 min to decompose S-nitrosothiols prior to measurement of AK activity.…”

“…For example, the L-Type Ca 2ϩ Channel and mitochondrial complex I were demonstrated to be S-nitrosylated and this modification appears to confer protective effects against ischemia/reperfusion (IR) injury. 7,8) However, the systematic investigations of the overall protein targets of S-nitrosylation in the heart, or heart S-nitrosoproteome, is still at the very beginning stage, 8) and further studies are needed to validate or expand the reported results.…”

Catestatin reduces myocardial ischaemia/reperfusion injury: involvement of PI3K/Akt, PKCs, mitochondrial KATP channels and ROS signalling

“…The most likely explanation is that the ROS signal is carried by specific radical species and/or in specific intracellular compartment [26,40]. MPG, which concentrates 500-fold in mitochondria and is highly effective against some mitochondrial ROS [26,30], evidently, is able to scavenge the few radical species that signal the protection, but is not effective against I/R injury due to massive ROS production [13,14,26,30,34,39].…”

Inducible Alterations of Glutathione Levels in Adult Dopaminergic Midbrain Neurons Result in Nigrostriatal Degeneration

“…Brookes and colleagues have demonstrated recently that S-nitrosation of complex I results in its enzymatic inhibition both in situ and recently in vivo in an acute cardiac ischemia reperfusion model Tompkins et al, 2006;Nadtochiy et al, 2007). We first assessed S-NO protein levels within SN dopaminergic neurons by immunohistochemistry using monoclonal antibody directed against S-nitrosocysteine.…”