title: Glutathione redox state regulates mitochondrial reactive oxygen production.
abstract: Oxidative stress induced by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD; dioxin) is poorly understood. Following one dose of TCDD (5 microg/kg body weight), mitochondrial succinate-dependent production of superoxide and H2O2 in mouse liver doubled at 7-28 days, then subsided by day 56; concomitantly, levels of GSH and GSSG increased in both cytosol and mitochondria. Cytosol displayed a typical oxidative stress response, consisting of diminished GSH relative to GSSG, decreased potential to reduce protein-SSG mixed disulfide bonds (type 1 thiol redox switch) or protein-SS-protein disulfide bonds (type 2 thiol redox switch), and a +10 mV change in GSSG/2GSH reduction potential. In contrast, mitochondria showed a rise in reduction state, consisting of increased GSH relative to GSSG, increases in type 1 and type 2 thiol redox switches, and a -25 mV change in GSSG/2GSH reduction potential. Comparing Ahr(-/-) knock-out and wild-type mice, we found that TCDD-induced thiol changes in both cytosol and mitochondria were dependent on the aromatic hydrocarbon receptor (AHR). GSH was rapidly taken up by mitochondria and stimulated succinate-dependent H2O2 production. A linear dependence of H2O2 production on the reduction potential for GSSG/2GSH exists between -150 and -300 mV. The TCDD-stimulated increase in succinate-dependent and thiol-stimulated production of reactive oxygen paralleled a four-fold increase in formamidopyrimidine DNA N-glycosylase (FPG)-sensitive cleavage sites in mitochondrial DNA, compared with a two-fold increase in nuclear DNA. These results suggest that TCDD produces an AHR-dependent oxidative stress in mitochondria, with concomitant mitochondrial DNA damage mediated, at least in part, by an increase in the mitochondrial thiol reduction state.
authors.affiliation: Department of Environmental Health and Center for Environmental Genetics, University of Cincinnati Medical Center, P. O. Box 670056, Cincinnati, Ohio 45267-0056, USA.
authors.forename: Dongxiao
authors.initials: D
authors.lastname: Shen
authors.forename: Timothy P
authors.initials: TP
authors.lastname: Dalton
authors.forename: Daniel W
authors.initials: DW
authors.lastname: Nebert
authors.forename: Howard G
authors.initials: HG
authors.lastname: Shertzer
mesh_terms: D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D005978:Glutathione / Q000378:metabolism*; D019803:Glutathione Disulfide / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism*; D010084:Oxidation-Reduction; D000072317:Polychlorinated Dibenzodioxins / Q000494:pharmacology; D017382:Reactive Oxygen Species / Q000378:metabolism*; D018336:Receptors, Aryl Hydrocarbon / Q000235:genetics; D013723:Teratogens / Q000494:pharmacology
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D005978:Glutathione; D019803:Glutathione Disulfide; D006861:Hydrogen Peroxide; D000072317:Polychlorinated Dibenzodioxins; D017382:Reactive Oxygen Species; D018336:Receptors, Aryl Hydrocarbon; D013723:Teratogens; C484722:Ahr protein, mouse