title: Basal reactive oxygen species determine the susceptibility to apoptosis in cirrhotic hepatocytes.
abstract: Hepatocytes from cirrhotic murine livers exhibit increased basal ROS activity and resistance to TGFbeta-induced apoptosis, yet when ROS levels are decreased by antioxidant pretreatment, these cells recover susceptibility to apoptotic stimuli. To further study these redox events, hepatocytes from cirrhotic murine livers were pretreated with various antioxidants prior to TGFbeta treatment and the ROS activity, apoptotic response, and mitochondrial ROS generation were assessed. In addition, normal hepatocytes were treated with low-dose H(2)O(2) and ROS and apoptotic responses determined. Treatment of cirrhotic hepatocytes with various antioxidants decreased basal ROS and rendered them susceptible to apoptosis. Examination of normal hepatocytes by confocal microscopy demonstrated colocalization of ROS activity and respiring mitochondria. Basal assessment of cirrhotic hepatocytes showed nonfocal ROS activity that was abolished by antioxidants. After pretreatment with an adenovirus expressing MnSOD, basal cirrhotic hepatocyte ROS were decreased and TGFbeta-induced colocalization of ROS and mitochondrial respiration was present. Treatment of normal hepatocytes with H(2)O(2) resulted in a sustained increase in ROS and resistance to TGFbeta apoptosis that was reversed when these cells were pretreated with an antioxidant. In conclusion, cirrhotic hepatocytes have a nonfocal distribution of ROS. However, normal and cirrhotic hepatocytes exhibit mitochondrial localization of ROS that is necessary for apoptosis.
authors.affiliation: Department of Surgery, University of North Carolina, Chapel Hill, NC 27599, USA.
authors.forename: Jay
authors.initials: J
authors.lastname: Raval
authors.forename: Suzanne
authors.initials: S
authors.lastname: Lyman
authors.forename: Takashi
authors.initials: T
authors.lastname: Nitta
authors.forename: Dagmara
authors.initials: D
authors.lastname: Mohuczy
authors.forename: John J
authors.initials: JJ
authors.lastname: Lemasters
authors.forename: Jae-Sung
authors.initials: JS
authors.lastname: Kim
authors.forename: Kevin E
authors.initials: KE
authors.lastname: Behrns
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D017209:Apoptosis / Q000502:physiology*; D020169:Caspases / Q000378:metabolism; D002478:Cells, Cultured; D004198:Disease Susceptibility; D022781:Hepatocytes / Q000378:metabolism* / Q000473:pathology; D006861:Hydrogen Peroxide / Q000494:pharmacology; D015151:Immunoblotting; D008103:Liver Cirrhosis / Q000378:metabolism / Q000473:pathology*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008930:Mitochondria, Liver / Q000378:metabolism; D016877:Oxidants / Q000494:pharmacology; D017382:Reactive Oxygen Species / Q000378:metabolism*; D016212:Transforming Growth Factor beta / Q000378:metabolism
chemical_list: D000975:Antioxidants; D016877:Oxidants; D017382:Reactive Oxygen Species; D016212:Transforming Growth Factor beta; D006861:Hydrogen Peroxide; D020169:Caspases