title: Interferon regulatory factor 1 binding to p300 stimulates DNA-dependent acetylation of p53.
abstract: Interferon regulatory factor 1 (IRF-1) and p53 control distinct sets of downstream genes; however, these two antioncogenic transcription factors converge to regulate p21 gene expression and to inhibit tumor formation. Here we investigate the mechanism by which IRF-1 and p53 synergize at the p21 promoter and show that stimulation of p21 transcription by IRF-1 does not require its DNA-binding activity but relies on the ability of IRF-1 to bind the coactivator p300 and to stimulate p53-dependent transcription by an allosteric mechanism. Deletion of the p300-binding sites in IRF-1 eliminates the ability of IRF-1 to stimulate p53 acetylation and associated p53 activity. Complementing this, small peptides derived from the IRF-1-p300 interface can bind to p300, stabilize the binding of p300 to DNA-bound p53, stimulate p53 acetylation in trans, and up-regulate p53-dependent activity from the p21 promoter. The nonacetylatable p53 mutant (p53-6KR) cannot be stimulated by IRF-1, further suggesting that p53 acetylation is the mechanism whereby IRF-1 modifies p53 activity. These data expand the core p300-p53 protein LXXLL and PXXP interface by including an IRF-1-p300 interface as an allosteric modifier of DNA-dependent acetylation of p53 at the p21 promoter.
authors.affiliation: CRUK Interferon and Cell Signalling Group, Cell Signalling Unit, Cancer Research Centre, University of Edinburgh, Western General Hospital, Crewe Road South, Edinburgh EH4 2XR, United Kingdom.
authors.forename: David
authors.initials: D
authors.lastname: Dornan
authors.forename: Mirjam
authors.initials: M
authors.lastname: Eckert
authors.forename: Maura
authors.initials: M
authors.lastname: Wallace
authors.forename: Harumi
authors.initials: H
authors.lastname: Shimizu
authors.forename: Eleanor
authors.initials: E
authors.lastname: Ramsay
authors.forename: Ted R
authors.initials: TR
authors.lastname: Hupp
authors.forename: Kathryn L
authors.initials: KL
authors.lastname: Ball
mesh_terms: D000107:Acetylation; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins / Q000235:genetics; D004247:DNA / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D050881:E1A-Associated p300 Protein; D006801:Humans; D050856:Interferon Regulatory Factor-1; D051379:Mice; D008954:Models, Biological; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D010750:Phosphoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*; D016159:Tumor Suppressor Protein p53 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: C493956:CDKN1A protein, human; C493957:Cdkn1a protein, mouse; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D004268:DNA-Binding Proteins; C494257:IRF1 protein, human; D050856:Interferon Regulatory Factor-1; C494258:Irf1 protein, mouse; D009687:Nuclear Proteins; D010750:Phosphoproteins; D011994:Recombinant Proteins; D015534:Trans-Activators; D016159:Tumor Suppressor Protein p53; D004247:DNA; D050881:E1A-Associated p300 Protein; C494361:Ep300 protein, mouse