[Reactive oxygen species signaling and redox homeostasis regulated by 8-nitro-cGMP]

An emerging aspect of redox signaling is the signaling pathway mediated by electrophilic byproducts, such as nitrated cyclic nucleotide (8-nitro-cGMP), generated via reactions of reactive oxygen species (ROS), NO, and their secondary products. We recently clarified that enzymatically-generated hydrosulfide derivatives regulate the metabolism and signaling of 8-nitro-cGMP. Although hydrogen sulfide was proposed to be a gaseous signaling mediator, its exact nature and physiological functions remain obscure. We thus found that particular hydropersulfide derivatives rather than hydrogen sulfide greatly ameliorated chronic heart failure after myocardial infarction in vivo in mice. This potent cardioprotective effect resulted from strong suppression of H-Ras signaling activated by electrophilic stimulation with 8-nitro-cGMP functioning as a second messenger for the redox signaling induced by NO and ROS. A significant amount of 8-nitro-cGMP was formed in the heart tissue after myocardial infarction, and hydrogen sulfide exogenously administered completely nullified this formation. We have reportedly shown that hydropersulfide effectively thiolated electrophiles in cells, which is best represented by 8-nitro-cGMP. Our current study indicates that electrophile thiolation may be a unique mechanism regulating ROS signaling and redox homeostasis, which may thus promote further development of prophylactic and therapeutic options for oxidative stress-related diseases.