Suppression of neuronal apoptosis by S-nitrosylation of caspases.

S-Nitrosylation (reaction of nitric oxide (NO) species with a critical cysteine sulfhydryl) can regulate the physiological activity of proteins, including enzymes, ion channels, G-proteins, and transcription factors. Caspases are a family of interleukin-1beta-converting enzyme-like proteases involved in the signaling pathway to apoptotic cell death, and each member of this enzyme family contains a critical cysteine residue in its active site. Here we show that S-nitrosylation of caspases in human embryonic kidney (HEK)-293 cells and primary cerebrocortical neurons decreases enzyme activity and is associated with protection from apoptosis.