title: Activation of hepatic Nrf2 in vivo by acetaminophen in CD-1 mice.
abstract: The transcription factor NF-E2-related factor 2 (Nrf2) plays an essential role in the mammalian response to chemical and oxidative stress through induction of hepatic phase II detoxification enzymes and regulation of glutathione (GSH). Enhanced liver damage in Nrf2-deficient mice treated with acetaminophen suggests a critical role for Nrf2; however, direct evidence for Nrf2 activation following acetaminophen exposure was previously lacking. We show that acetaminophen can initiate nuclear translocation of Nrf2 in vivo, with maximum levels reached after 1 hour, in a dose dependent manner, at doses below those causing overt liver damage. Furthermore, Nrf2 was shown to be functionally active, as assessed by the induction of epoxide hydrolase, heme oxygenase-1, and glutamate cysteine ligase gene expression. Increased nuclear Nrf2 was found to be associated with depletion of hepatic GSH. Activation of Nrf2 is considered to involve dissociation from a cytoplasmic inhibitor, Kelch-like ECH-associated protein 1 (Keap1), through a redox-sensitive mechanism involving either GSH depletion or direct chemical interaction through Michael addition. To investigate acetaminophen-induced Nrf2 activation we compared the actions of 2 other GSH depleters, diethyl maleate (DEM) and buthionine sulphoximine (BSO), only 1 of which (DEM) can function as a Michael acceptor. For each compound, greater than 60% depletion of GSH was achieved; however, in the case of BSO, this depletion did not cause nuclear translocation of Nrf2. In conclusion, GSH depletion alone is insufficient for Nrf2 activation: a more direct interaction is required, possibly involving chemical modification of Nrf2 or Keap1, which is facilitated by the prior loss of GSH.
authors.affiliation: Department of Pharmacology and Therapeutics, University of Liverpool, Liverpool, Merseyside, UK.
authors.forename: Christopher E P
authors.initials: CE
authors.lastname: Goldring
authors.forename: Neil R
authors.initials: NR
authors.lastname: Kitteringham
authors.forename: Robert
authors.initials: R
authors.lastname: Elsby
authors.forename: Laura E
authors.initials: LE
authors.lastname: Randle
authors.forename: Yuri N
authors.initials: YN
authors.lastname: Clement
authors.forename: Dominic P
authors.initials: DP
authors.lastname: Williams
authors.forename: Michael
authors.initials: M
authors.lastname: McMahon
authors.forename: John D
authors.initials: JD
authors.lastname: Hayes
authors.forename: Ken
authors.initials: K
authors.lastname: Itoh
authors.forename: Masayuki
authors.initials: M
authors.lastname: Yamamoto
authors.forename: B Kevin
authors.initials: BK
authors.lastname: Park
mesh_terms: D000082:Acetaminophen / Q000494:pharmacology*; D018712:Analgesics, Non-Narcotic / Q000494:pharmacology*; D000818:Animals; D015152:Blotting, Northern; D002467:Cell Nucleus / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression / Q000187:drug effects; D005978:Glutathione / Q000378:metabolism; D008099:Liver / Q000187:drug effects* / Q000378:metabolism*; D008297:Male; D008298:Maleates / Q000494:pharmacology; D051379:Mice; D008815:Mice, Inbred Strains; D051267:NF-E2-Related Factor 2; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*
chemical_list: D018712:Analgesics, Non-Narcotic; D004268:DNA-Binding Proteins; D008298:Maleates; D051267:NF-E2-Related Factor 2; C495636:Nfe2l2 protein, mouse; D015534:Trans-Activators; D000082:Acetaminophen; C014476:diethyl maleate; D005978:Glutathione