Hypoxia/reoxygenation induces apoptosis through a ROS-mediated caspase-8/Bid/Bax pathway in human lymphocytes.
Recently, we showed that hypoxia/reoxygenation (H/R) induced apoptosis in human lymphocytes via reactive oxygen species (ROS) generation and disruption of the mitochondrial membrane; however, the signaling mechanisms responsible for these events are unclear. Here, we investigated the mechanism of H/R-induced apoptosis in human cultured lymphocytes. H/R increased the proportion of apoptotic cells, while z-IETD-fmk, z-VAD-fmk, and z-DEVD-fmk inhibited H/R-induced apoptosis. H/R also enhanced caspase-3 and caspase-8 activity. Time-sequence analysis of the induction of apoptosis by H/R revealed that H/R triggers apoptosis through a mitochondrial pathway involving caspase-8, Bid cleavage, and Bax activation. Furthermore, suppression of caspase-8 activity with z-IETD-fmk prevented Bid cleavage and Bax activation during apoptosis. N-acetylcysteine (NAC), a well-known ROS scavenger, suppressed caspase-8 activation and the subsequent cleavage of caspase-9 and caspase-3, indicating the role of ROS in caspase-8-mediated apoptosis. Overall, our results indicate that H/R induces apoptosis via a mitochondrial pathway involving caspase-8/Bid/Bax activation in human lymphocytes. Our results also suggest that ROS are critical regulators of caspase-8-mediated apoptosis in H/R-treated human lymphocytes.
Kim
Byeong Mo
BM
School of Public Health and Institute of Health and Environment, 28 Yunkeun-dong, Chongno-ku, Seoul National University, Seoul 110-460, Republic of Korea.
Chung
Hai Won
HW
D000111:Acetylcysteine / Q000494:pharmacology; D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism*; D051023:BH3 Interacting Domain Death Agonist Protein / Q000378:metabolism; D015153:Blotting, Western; D053148:Caspase 3 / Q000378:metabolism; D053181:Caspase 8 / Q000378:metabolism; D053453:Caspase 9 / Q000378:metabolism; D061945:Caspase Inhibitors; D015687:Cell Hypoxia / Q000502:physiology; D002478:Cells, Cultured; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D006801:Humans; D008214:Lymphocytes / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D008928:Mitochondria / Q000378:metabolism; D010100:Oxygen / Q000494:pharmacology*; D011487:Protein Conformation / Q000187:drug effects; D021381:Protein Transport / Q000187:drug effects; D017382:Reactive Oxygen Species / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects* / Q000502:physiology; D013997:Time Factors; D051028:bcl-2-Associated X Protein / Q000737:chemistry / Q000378:metabolism
D000590:Amino Acid Chloromethyl Ketones; D051017:Apoptosis Regulatory Proteins; C494826:BAX protein, human; D051023:BH3 Interacting Domain Death Agonist Protein; C494814:BID protein, human; D061945:Caspase Inhibitors; D015853:Cysteine Proteinase Inhibitors; D017382:Reactive Oxygen Species; D051028:bcl-2-Associated X Protein; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; D053148:Caspase 3; D053181:Caspase 8; D053453:Caspase 9; D010100:Oxygen; D000111:Acetylcysteine