Bcl-2 prevents mitochondrial permeability transition and cytochrome c release via maintenance of reduced pyridine nucleotides.
Digitonin-permeabilized PC12 and GT1-7 neural cells exhibited a cyclosporin A-sensitive decrease in mitochondrial membrane potential, increased volume, and release of the pro-apoptotic factor cytochrome c in the presence of Ca2+ and the mitochondrial permeability transition (MPT) inducers t-butyl hydroperoxide (t-bOOH) or phenylarsine oxide (PhAsO). Although the concentration of PhAsO required to induce the MPT was similar for Bcl-2 negative and Bcl-2 overexpressing transfected cells (Bcl-2(+)), the level of t-bOOH necessary for triggering the MPT was much higher for Bcl-2(+) cells. A higher concentration of t-bOOH was also necessary for promoting the oxidation of mitochondrial pyridine nucleotides in Bcl-2(+) cells. The sensitivity of Bcl-2(- ) cell mitochondria to t-bOOH but not PhAsO could be overcome by the use of conditions that protect the pyridine nucleotides against oxidation. We conclude that the increased ability of Bcl-2(+) cells to maintain mitochondrial pyridine nucleotides in a reduced redox state is a sufficient explanation for their resistance to MPT under conditions of oxidative stress induced by Ca2+ plus t-bOOH.
Kowaltowski
A J
AJ
Department of Anesthesiology, The University of Maryland Baltimore, Baltimore, MD, USA.
Vercesi
A E
AE
Fiskum
G
G
D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D002118:Calcium / Q000378:metabolism; D002463:Cell Membrane Permeability / Q000187:drug effects / Q000502:physiology; D016572:Cyclosporine / Q000494:pharmacology; D003574:Cytochrome c Group / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D008928:Mitochondria / Q000378:metabolism*; D009243:NAD / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism; D010084:Oxidation-Reduction; D018384:Oxidative Stress / Q000502:physiology; D016716:PC12 Cells; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism* / Q000494:pharmacology; D051381:Rats
D003574:Cytochrome c Group; D004791:Enzyme Inhibitors; D019253:Proto-Oncogene Proteins c-bcl-2; D009243:NAD; D016572:Cyclosporine; D002118:Calcium