title: NAD(P)H:quinone acceptor oxidoreductase 1 (NQO1), a multifunctional antioxidant enzyme and exceptionally versatile cytoprotector.
abstract: NAD(P)H:quinone acceptor oxidoreductase 1 (NQO1) is a widely-distributed FAD-dependent flavoprotein that promotes obligatory 2-electron reductions of quinones, quinoneimines, nitroaromatics, and azo dyes, at rates that are comparable with NADH or NADPH. These reductions depress quinone levels and thereby minimize opportunities for generation of reactive oxygen intermediates by redox cycling, and for depletion of intracellular thiol pools. NQO1 is a highly-inducible enzyme that is regulated by the Keap1/Nrf2/ARE pathway. Evidence for the importance of the antioxidant functions of NQO1 in combating oxidative stress is provided by demonstrations that induction of NQO1 levels or their depletion (knockout, or knockdown) are associated with decreased and increased susceptibilities to oxidative stress, respectively. Furthermore, benzene genotoxicity is markedly enhanced when NQO1 activity is compromised. Not surprisingly, human polymorphisms that suppress NQO1 activities are associated with increased predisposition to disease. Recent studies have uncovered protective roles for NQO1 that apparently are unrelated to its enzymatic activities. NQO1 binds to and thereby stabilizes the important tumor suppressor p53 against proteasomal degradation. Indeed, NQO1 appears to regulate the degradative fate of other proteins. These findings suggest that NQO1 may exercise a selective "gatekeeping" role in regulating the proteasomal degradation of specific proteins, thereby broadening the cytoprotective role of NQO1 far beyond its highly effective antioxidant functions.
authors.affiliation: Biomedical Research Institute, University of Dundee, Dundee, Scotland, UK.
authors.forename: Albena T
authors.initials: AT
authors.lastname: Dinkova-Kostova
authors.forename: Paul
authors.initials: P
authors.lastname: Talalay
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000378:metabolism*; D004967:Estrogens / Q000378:metabolism / Q000633:toxicity; D055785:Gene Knockdown Techniques; D055786:Gene Knockout Techniques; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D000072019:Kelch-Like ECH-Associated Protein 1; D008954:Models, Biological; D016660:NAD(P)H Dehydrogenase (Quinone) / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D018384:Oxidative Stress; D011110:Polymorphism, Genetic; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D011485:Protein Binding; D055550:Protein Stability; D011809:Quinones / Q000378:metabolism / Q000633:toxicity; D015398:Signal Transduction; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism
chemical_list: D000975:Antioxidants; D004967:Estrogens; D047908:Intracellular Signaling Peptides and Proteins; C431364:KEAP1 protein, human; D000072019:Kelch-Like ECH-Associated Protein 1; D011809:Quinones; C495901:TP53 protein, human; D016159:Tumor Suppressor Protein p53; D016660:NAD(P)H Dehydrogenase (Quinone); C447479:NQO1 protein, human; D046988:Proteasome Endopeptidase Complex