Mechanism of A23187-induced apoptosis in HL-60 cells: dependency on mitochondrial permeability transition but not on NADPH oxidase.
Calcium ions (Ca(2+)) are involved in a number of physiological cellular functions including apoptosis. An elevation in intracellular levels of Ca(2+) in A23187-treated HL-60 cells was associated with the generation of both intracellular and extracellular reactive oxygen species (ROS) and induction of apoptotic cell death. A23187-induced apoptosis was prevented by cyclosporin A, a potent inhibitor of mitochondrial permeability transition (MPT). The generation of extracellular ROS was suppressed by the NADPH oxidase inhibitor diphenylene iodonium, and by superoxide dismutase, but these agents had no effect on A23187-induced apoptosis. In contrast, the blocking of intracellular ROS by a cell-permeant antioxidant diminished completely the induction of MPT and apoptosis. In isolated mitochondria, the addition of Ca(2+) induced a typical MPT concomitant with the generation of ROS, which leads to augmentation of intracellular ROS levels. These results indicate that intracellular not extracellular ROS generated by A23187 is associated with the opening of MPT pores that leads to apoptotic cell death.
Kajitani
Noriko
N
Department of Cell Chemistry, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama 700-8558, Japan.
Kobuchi
Hirotsugu
H
Fujita
Hirofumi
H
Yano
Hiromi
H
Fujiwara
Takuzo
T
Yasuda
Tatsuji
T
Utsumi
Kozo
K
D017209:Apoptosis; D000001:Calcimycin / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism*; D016572:Cyclosporine / Q000494:pharmacology; D053938:DNA Fragmentation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D018922:HL-60 Cells; D006801:Humans; D007476:Ionophores / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism*; D019255:NADPH Oxidases / Q000378:metabolism; D010539:Permeability; D017382:Reactive Oxygen Species / Q000378:metabolism
D004791:Enzyme Inhibitors; D007476:Ionophores; D017382:Reactive Oxygen Species; D000001:Calcimycin; D016572:Cyclosporine; D019255:NADPH Oxidases; D002118:Calcium