Early redox imbalance mediates hydroperoxide-induced apoptosis in mitotic competent undifferentiated PC-12 cells.
Our recent study has demonstrated that cellular redox imbalance can directly initiate apoptosis in a mitotic competent PC-12 cell line without the involvement of reactive oxygen species (ROS). However, whether cell apoptosis induced by ROS is, in fact, mediated by a loss of redox balance caused by the oxidant is unresolved. The linkage between oxidant-mediated apoptosis and the induction of cellular redox was examined in PC-12 cells using the oxidant, tert-butylhydroperoxide (TBH). TBH caused cell apoptosis in 24 h that was preceded by an early increase (30 min) in oxidized glutathione (GSSG). Pretreatment with N-acetyl cysteine prevented TBH-induced GSSG increases and cell apoptosis. Altered Bax/BcL-2 expression and release of mitochondrial cytochrome c occurred post-redox imbalance and was kinetically linked to caspase-3 activation and poly ADP-ribose polymerase cleavage. Moreover, cell apoptosis was attenuated by inhibition of caspase-9, but not caspase-8, and blockade of mitochondrial ROS generation and permeability transition pore attenuated caspase 3 activation and cell apoptosis. Collectively, these results show that TBH-induced GSSG elevation is associated with the disruption of mitochondrial integrity, activation of caspase-3 and cell apoptosis. This redox induction of the apoptotic cascade was dissociated from cellular GSH efflux.
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Department of Molecular and Cellular Physiology, Louisiana State University Health Sciences Center, Shreveport, LA 71130-3932, USA.
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D000111:Acetylcysteine / Q000494:pharmacology; D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D053148:Caspase 3; D020169:Caspases / Q000187:drug effects / Q000378:metabolism; D003574:Cytochrome c Group / Q000187:drug effects / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005057:Eukaryotic Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D005978:Glutathione / Q000187:drug effects / Q000378:metabolism* / Q000494:pharmacology; D007700:Kinetics; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism*; D008938:Mitosis / Q000187:drug effects / Q000502:physiology; D018384:Oxidative Stress / Q000187:drug effects / Q000502:physiology*; D016716:PC12 Cells; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases; D011506:Proteins / Q000187:drug effects / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000187:drug effects / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D017382:Reactive Oxygen Species / Q000037:antagonists & inhibitors / Q000378:metabolism; D051028:bcl-2-Associated X Protein; D020122:tert-Butylhydroperoxide / Q000494:pharmacology*
C494828:Bax protein, rat; D003574:Cytochrome c Group; D004791:Enzyme Inhibitors; D011506:Proteins; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D017382:Reactive Oxygen Species; D051028:bcl-2-Associated X Protein; D020122:tert-Butylhydroperoxide; C499322:Parp1 protein, rat; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases; C505410:Casp3 protein, rat; D053148:Caspase 3; D020169:Caspases; D005978:Glutathione; D000111:Acetylcysteine