Activation of the NRF2 signaling pathway by copper-mediated redox cycling of para- and ortho-hydroquinones.
Transcription factor NF-E2 p45-related factor 2 (Nrf2) mediates adaptation to oxidants and electrophiles through up-regulating genes that contain antioxidant response elements (AREs) in their promoters. Using the stably transfected human AREc32 reporter cell line, we found that copper and other transition metals enhanced induction of ARE-driven luciferase by 2-tert-butyl-1,4-hydroquinone (tBHQ) as a result of increased oxidation to 2-tert-butyl-1,4-benzoquinone (tBQ). Following exposure to tBHQ for 30 min, ARE-luciferase activity measured after 24 hr was dependent on the presence of Cu(2+). In contrast, tBQ-induced activity was Cu(2+)-independent. The metal-catalyzed oxidation of tBHQ to tBQ occured rapidly and stoichiometrically. Compounds that share para- or ortho-hydroquinone structures, such as catechol estrogens, dopamine, and l-DOPA, also induced ARE-driven luciferase in a Cu(2+)-dependent manner. Thus, the oxidation of para- and ortho-hydroquinones to quinones represents the rate-limiting step in the activation of Nrf2.
Cancer Research UK Molecular Pharmacology Unit, Biomedical Research Institute, Ninewells Hospital and Medical School, University of Dundee, Dundee, Scotland, UK.
Xiu Jun
XJ
Wang
John D
JD
Hayes
Larry G
LG
Higgins
C Roland
CR
Wolf
Albena T
AT
Dinkova-Kostova
D016227:Benzoquinones / Q000378:metabolism; D002395:Catecholamines / Q000378:metabolism; D002396:Catechols / Q000378:metabolism; D002460:Cell Line; D003300:Copper / Q000378:metabolism*; D005786:Gene Expression Regulation; D017930:Genes, Reporter; D005978:Glutathione / Q000378:metabolism; D006801:Humans; D006873:Hydroquinones / Q000378:metabolism*; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D000072019:Kelch-Like ECH-Associated Protein 1; D008156:Luciferases / Q000235:genetics / Q000378:metabolism; D051267:NF-E2-Related Factor 2 / Q000378:metabolism*; D010084:Oxidation-Reduction; D010100:Oxygen / Q000378:metabolism; D010636:Phenols / Q000378:metabolism
D016227:Benzoquinones; D002395:Catecholamines; D002396:Catechols; D006873:Hydroquinones; D047908:Intracellular Signaling Peptides and Proteins; C431364:KEAP1 protein, human; D000072019:Kelch-Like ECH-Associated Protein 1; D051267:NF-E2-Related Factor 2; D010636:Phenols; C004532:quinone; D003300:Copper; D008156:Luciferases; D005978:Glutathione; D010100:Oxygen; C031927:hydroquinone