Oxidative stress triggers neuronal caspase-independent death: endonuclease G involvement in programmed cell death-type III.
To characterize neuronal death, primary cortical neurons (C57/Black 6 J mice) were exposed to hydrogen peroxide (H2O2) and staurosporine. Both caused cell shrinkage, nuclear condensation, DNA fragmentation and loss of plasma membrane integrity. Neither treatment induced caspase-7 activity, but caspase-3 was activated by staurosporine but not H2O2. Each treatment caused redistribution from mitochondria of both endonuclease G (Endo G) and cytochrome c. Neurons knocked down for Endo G expression using siRNA showed reduction in both nuclear condensation and DNA fragmentation after treatment with H2O2, but not staurosporine. Endo G suppression protected cells against H2O2-induced cell death, while staurosporine-induced death was merely delayed. We conclude that staurosporine induces apoptosis in these neurons, but severe oxidative stress leads to Endo G-dependent death, in the absence of caspase activation (programmed cell death-type III). Therefore, oxidative stress triggers in neurons a form of necrosis that is a systematic cellular response subject to molecular regulation.
Higgins
Gavin C
GC
Department of Biochemistry and Molecular Biology, Monash University, Building 13D, Clayton Campus, Clayton, VIC 3800, Australia.
Beart
Philip M
PM
Nagley
Phillip
P
D000818:Animals; D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D053148:Caspase 3 / Q000378:metabolism / Q000502:physiology; D053179:Caspase 7 / Q000378:metabolism / Q000502:physiology; D053470:Caspases, Effector / Q000378:metabolism / Q000502:physiology*; D053938:DNA Fragmentation / Q000187:drug effects; D004706:Endodeoxyribonucleases / Q000378:metabolism / Q000502:physiology*; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D051379:Mice; D008815:Mice, Inbred Strains; D051336:Mitochondrial Membranes / Q000187:drug effects; D009474:Neurons / Q000166:cytology / Q000187:drug effects*; D018384:Oxidative Stress; D019311:Staurosporine / Q000494:pharmacology*
D006861:Hydrogen Peroxide; D004706:Endodeoxyribonucleases; C052391:endonuclease G; C505409:Casp3 protein, mouse; C505524:Casp7 protein, mouse; D053148:Caspase 3; D053179:Caspase 7; D053470:Caspases, Effector; D019311:Staurosporine