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.
Department of Molecular and Cellular Physiology, Louisiana State University Health Sciences Center, Shreveport, LA 71130-3932, USA.
E K
EK
Pias
T Y
TY
Aw
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