title: Regulation of reactive oxygen species-induced apoptosis and necrosis by caspase 3-like proteases.
abstract: Reactive oxygen species (ROS) and caspases have been implicated as potential mediators of cell death. However, their mechanistic relationship remains to be elucidated. Here we investigated the roles of caspases in apoptosis and necrosis induced by ROS, generated by the mixture of xanthine and xanthine oxidase (X/XO). A low concentration of XO (0.025 U/ml) induced DNA fragmentation with little cellular membrane damage 3 h after treatment, suggesting the induction of apoptosis. The same treatment induced membrane blebbing, a morphological change typical of apoptosis, 15 min after treatment. A high concentration of XO (0.1 U/ml) damaged cell membranes with little concomitance of DNA fragmention, suggesting the induction of necrosis. ROS also activated caspase 3-like proteases and caspase 3 itself together with the release of cytochrome c which might be the cause of caspase activation. Apoptosis induced by low concentrations of XO and necrosis induced by high concentrations of XO was inhibited by z-DEVD-CH2F, an irreversible inhibitor of caspase 3. However, rapid induction of membrane blebbing was not inhibited by z-DEVD-CH2F. These results suggest that both apoptosis and necrosis could be induced by ROS through the activation of caspase 3-like protease; however, caspase 3 activation is not needed for ROS-induced membrane blebbing.
authors.affiliation: Research Center for Cardiovascular Diseases, Institute of Molecular Medicine for the Prevention of Human Diseases, The University of Texas-Houston Health Science Center, 77030, USA.
authors.forename: M
authors.initials: M
authors.lastname: Higuchi
authors.forename: T
authors.initials: T
authors.lastname: Honda
authors.forename: R J
authors.initials: RJ
authors.lastname: Proske
authors.forename: E T
authors.initials: ET
authors.lastname: Yeh
mesh_terms: D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D053148:Caspase 3; D020169:Caspases / Q000502:physiology*; D002462:Cell Membrane / Q000187:drug effects / Q000648:ultrastructure; D003574:Cytochrome c Group / Q000378:metabolism; D053938:DNA Fragmentation; D010450:Endopeptidases / Q000502:physiology*; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D007951:Leukemia, Myeloid / Q000473:pathology; D009336:Necrosis; D009363:Neoplasm Proteins / Q000502:physiology; D018384:Oxidative Stress; D011480:Protease Inhibitors / Q000494:pharmacology; D017382:Reactive Oxygen Species; D014407:Tumor Cells, Cultured; D019820:Xanthine / Q000378:metabolism; D014969:Xanthine Oxidase / Q000378:metabolism
chemical_list: D003574:Cytochrome c Group; D004791:Enzyme Inhibitors; D009363:Neoplasm Proteins; D011480:Protease Inhibitors; D017382:Reactive Oxygen Species; D019820:Xanthine; D014969:Xanthine Oxidase; D010450:Endopeptidases; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases