Nitric Oxide Reversibly Inhibits Seven Members of the Caspase Family via S-Nitrosylation

• Published in: Biochemical and biophysical research communications Vol. 240; no. 2; pp. 419 - 424
• Main Authors: Li, Jianrong, Billiar, Timothy R., Talanian, Robert V., Kim, Young M.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 17.11.1997
• Subjects: Animals; Apoptosis - drug effects; Borates - pharmacology; Cells, Cultured; Cysteine Endopeptidases - metabolism; Cysteine Proteinase Inhibitors - pharmacology; Cytosol - enzymology; Dactinomycin - pharmacology; Dithiothreitol - pharmacology; Humans; Kinetics; Liver - cytology; Liver - drug effects; Liver - enzymology; Male; Mercuric Chloride - pharmacology; Molsidomine - analogs & derivatives; Molsidomine - pharmacology; Nitric Oxide - pharmacology; Nitroso Compounds; Penicillamine - analogs & derivatives; Penicillamine - pharmacology; Rats; Rats, Sprague-Dawley; S-Nitroso-N-Acetylpenicillamine; Signal Transduction; Tumor Necrosis Factor-alpha - pharmacology
• ISSN: 0006-291X; 1090-2104
• DOI: 10.1006/bbrc.1997.7672

The caspases are a family of at least 10 human cysteine proteases that participate in cytokine maturation and in apoptotic signal transduction and execution mechanisms. Peptidic inhibitors of these enzymes are capable of blocking cytokine maturation and apoptosis, demonstrating their crucial roles in these processes. We have recently discovered that nitric oxide (NO), produced either extracellularly by NO donors or intracellularly by the inducible nitric oxide synthase, prevented apoptosis in hepatocytes. Caspase-3-like activity was found to be inhibited under these conditions. To investigate further the interaction between NO and caspases, we utilized purified human recombinant caspases and examined the effect of NO on enzymatic activities of different caspases. We report here that of the seven caspases studied, all were reversibly inhibited by NO. Dithiothreitol was able to reverse the NO inhibition, indicating direct S-nitrosylation of caspase catalytic cysteine residue by NO. Our results support the concept that NO is an endogenous regulator of caspase activity.