Role of Redox Controls of Caspase Activities in Regulation of Cell Death

Caspases are a family of aspartate-specific cysteine proteinases that play a critical role in the execution phase of apoptosis. They are normally present in cells in a proenzyme form that requires limited proteolysis for enzymatic activity. The processing of caspases needs the reduction of a cysteine residue as well as other cysteine residues around the catalytic site for enzymatic activity and dimerization via sulfhydryl groups. Therefore, both processing and activity are inhibited in the presence of an excess of an oxidant such as hydrogen peroxide or nitric oxide and thiol-oxidizing agents, and enhanced in the presence of an anti-oxidant such as dithiothreitol or glutathione. On the other hand, reactive oxygen species (ROS) released from mitochondria decrease the concentration of cellular glutathione during apoptosis. Under physiological conditions, ROS are needed for survival. The redox valance decides the fate of cells, survival or death involving apoptosis and necrosis. In this review, we discussed the relationship between the redox control of caspase activity and cell death.