title: NAD(P)H quinone oxidoreductase 1 inhibits the proteasomal degradation of the tumour suppressor p33(ING1b).
abstract: The tumour suppressor p33(ING1b) ((ING1b) for inhibitor of growth family, member 1b) is important in cellular stress responses, including cell-cycle arrest, apoptosis, chromatin remodelling and DNA repair; however, its degradation pathway is still unknown. Recently, we showed that genotoxic stress induces p33(ING1b) phosphorylation at Ser 126, and abolishment of Ser 126 phosphorylation markedly shortened its half-life. Therefore, we suggest that Ser 126 phosphorylation modulates the interaction of p33(ING1b) with its degradation machinery, stabilizing this protein. Combining the use of inhibitors of the main degradation pathways in the nucleus (proteasome and calpains), partial isolation of the proteasome complex, and in vitro interaction and degradation assays, we set out to determine the degradation mechanism of p33(ING1b). We found that p33(ING1b) is degraded in the 20S proteasome and that NAD(P)H quinone oxidoreductase 1 (NQO1), an oxidoreductase previously shown to modulate the degradation of p53 in the 20S proteasome, inhibits the degradation of p33(ING1b). Furthermore, ultraviolet irradiation induces p33(ING1b) phosphorylation at Ser 126, which, in turn, facilitates its interaction with NQO1.
authors.affiliation: Department of Dermatology and Skin Science, Jack Bell Research Centre, Vancouver Coastal Health Research Institute, University of British Columbia, 2660 Oak Street, Vancouver, British Columbia V6G 3Z6, Canada.
authors.forename: Marco
authors.initials: M
authors.lastname: Garate
authors.forename: Ronald P C
authors.initials: RP
authors.lastname: Wong
authors.forename: Eric I
authors.initials: EI
authors.lastname: Campos
authors.forename: Yemin
authors.initials: Y
authors.lastname: Wang
authors.forename: Gang
authors.initials: G
authors.lastname: Li
mesh_terms: D000111:Acetylcysteine / Q000031:analogs & derivatives / Q000378:metabolism; D000818:Animals; D002453:Cell Cycle / Q000502:physiology; D045744:Cell Line, Tumor; D003513:Cycloheximide / Q000378:metabolism; D015853:Cysteine Proteinase Inhibitors / Q000378:metabolism; D006801:Humans; D000076023:Inhibitor of Growth Protein 1; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism*; D007976:Leupeptins / Q000378:metabolism; D016660:NAD(P)H Dehydrogenase (Quinone) / Q000235:genetics / Q000378:metabolism*; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism*; D061988:Proteasome Inhibitors; D012694:Serine / Q000378:metabolism; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism*; D014466:Ultraviolet Rays
chemical_list: D015853:Cysteine Proteinase Inhibitors; C501503:ING1 protein, human; D000076023:Inhibitor of Growth Protein 1; D047908:Intracellular Signaling Peptides and Proteins; D007976:Leupeptins; D009687:Nuclear Proteins; D061988:Proteasome Inhibitors; D025521:Tumor Suppressor Proteins; C067713:lactacystin; D012694:Serine; D003513:Cycloheximide; D016660:NAD(P)H Dehydrogenase (Quinone); C447479:NQO1 protein, human; D046988:Proteasome Endopeptidase Complex; C072553:benzyloxycarbonylleucyl-leucyl-leucine aldehyde; D000111:Acetylcysteine