title: Role of caspases and NF-kappaB signaling in hydrogen peroxide- and superoxide-induced hepatocyte apoptosis.
abstract: Reactive oxygen intermediates (ROI) have been implicated as mediators of hepatocyte death resulting from a variety of forms of liver injury. To delineate the mechanisms that underlie ROI-induced apoptosis, the roles of caspase activation and nuclear factor-kappaB (NF-kappaB) signaling were determined in the rat hepatocyte cell line RALA255-10G after treatment with H(2)O(2) or the superoxide generator menadione. By 8 h, H(2)O(2) and menadione caused 26% and 33% cell death, respectively. Death from both ROI occurred by apoptosis as indicated by morphology under fluorescence microscopy, the induction of caspase activation and DNA fragmentation, and the cleavage of poly(ADP-ribose) polymerase. Despite the presence of caspase activation in both forms of apoptosis, caspase inhibition blocked H(2)O(2)- but not menadione-induced apoptosis. In contrast, inhibition of NF-kappaB activation decreased cell death from both ROI. Different ROI, therefore, induce distinct apoptotic pathways in RALA hepatocytes that are both caspase dependent and independent. In contrast to the known protective effect of NF-kappaB activation in tumor necrosis factor-alpha-induced hepatocyte apoptosis, NF-kappaB promotes hepatocellular death from ROI in these cells.
authors.affiliation: Department of Medicine, Marion Bessin Liver Research Center, Albert Einstein College of Medicine, Bronx, New York 10461, USA.
authors.forename: B E
authors.initials: BE
authors.lastname: Jones
authors.forename: C R
authors.initials: CR
authors.lastname: Lo
authors.forename: H
authors.initials: H
authors.lastname: Liu
authors.forename: Z
authors.initials: Z
authors.lastname: Pradhan
authors.forename: L
authors.initials: L
authors.lastname: Garcia
authors.forename: A
authors.initials: A
authors.lastname: Srinivasan
authors.forename: K L
authors.initials: KL
authors.lastname: Valentino
authors.forename: M J
authors.initials: MJ
authors.lastname: Czaja
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D053143:Caspase 2; D053148:Caspase 3; D053179:Caspase 7; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases / Q000378:metabolism*; D016923:Cell Death / Q000187:drug effects; D002460:Cell Line; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D008099:Liver / Q000166:cytology* / Q000187:drug effects / Q000502:physiology*; D016328:NF-kappa B / Q000378:metabolism*; D051381:Rats; D015398:Signal Transduction / Q000187:drug effects; D013481:Superoxides / Q000494:pharmacology*; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D014812:Vitamin K / Q000494:pharmacology*
chemical_list: D016328:NF-kappa B; D014409:Tumor Necrosis Factor-alpha; D013481:Superoxides; D014812:Vitamin K; D006861:Hydrogen Peroxide; C505410:Casp3 protein, rat; C505528:Casp8 protein, rat; C506435:Casp9 protein, rat; D053143:Caspase 2; D053148:Caspase 3; D053179:Caspase 7; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases