Hydrogen Sulfide and Cellular Redox Homeostasis

Intracellular redox imbalance is mainly caused by overproduction of reactive oxygen species (ROS) or weakness of the natural antioxidant defense system. It is involved in the pathophysiology of a wide array of human diseases. Hydrogen sulfide (H(2)S) is now recognized as the third “gasotransmitters” and proved to exert a wide range of physiological and cytoprotective functions in the biological systems. Among these functions, the role of H(2)S in oxidative stress has been one of the main focuses over years. However, the underlying mechanisms for the antioxidant effect of H(2)S are still poorly comprehended. This review presents an overview of the current understanding of H(2)S specially focusing on the new understanding and mechanisms of the antioxidant effects of H(2)S based on recent reports. Both inhibition of ROS generation and stimulation of antioxidants are discussed. H(2)S-induced S-sulfhydration of key proteins (e.g., p66Shc and Keap1) is also one of the focuses of this review.