title: Suppression of interferon β gene transcription by inhibitors of bromodomain and extra-terminal (BET) family members.
abstract: PLK (Polo-like kinase) inhibitors, such as BI-2536, have been reported to suppress IFNB (encoding IFNβ, interferon β) gene transcription induced by ligands that activate TLR3 (Toll-like receptor 3) and TLR4. In the present study, we found that BI-2536 is likely to exert this effect by preventing the interaction of the transcription factors IRF3 (interferon-regulatory factor 3) and c-Jun with the IFNB promoter, but without affecting the TBK1 {TANK [TRAF (tumour-necrosis-factor-receptor-associated factor)-associated nuclear factor κB activator]-binding kinase 1}-catalysed phosphorylation of IRF3 at Ser³⁹⁶, the dimerization and nuclear translocation of IRF3 or the phosphorylation of c-Jun and ATF2 (activating transcription factor 2). Although BI-2536 inhibits few other kinases tested, it interacts with BET (bromodomain and extra-terminal) family members and displaces them from acetylated lysine residues on histones. We found that BET inhibitors that do not inhibit PLKs phenocopied the effect of BI-2536 on IFNB gene transcription. Similarly, BET inhibitors blocked the interaction of IRF5 with the IFNB promoter and the secretion of IFNβ induced by TLR7 or TLR9 ligands in the human plasmacytoid dendritic cell line GEN2.2, but without affecting the nuclear translocation of IRF5. We found that the BET family member BRD4 (bromodomain-containing protein 4) was associated with the IFNB promoter and that this interaction was enhanced by TLR3- or TLR4-ligation and prevented by BI-2536 and other BET inhibitors. Our results establish that BET family members are essential for TLR-stimulated IFNB gene transcription by permitting transcription factors to interact with the IFNB promoter. They also show that the interaction of the IFNB promoter with BRD4 is regulated by TLR ligation and that BI-2536 is likely to suppress IFNB gene transcription by targeting BET family members.
authors.affiliation: MRC Protein Phosphorylation and Ubiquitylation Unit, College of Life Sciences, Dow Street, University of Dundee, Dundee DD1 5EH, Scotland, U.K.
authors.forename: Nazma
authors.initials: N
authors.lastname: Malik
authors.affiliation: MRC Protein Phosphorylation and Ubiquitylation Unit, College of Life Sciences, Dow Street, University of Dundee, Dundee DD1 5EH, Scotland, U.K.
authors.forename: Stefan
authors.initials: S
authors.lastname: Vollmer
authors.affiliation: MRC Protein Phosphorylation and Ubiquitylation Unit, College of Life Sciences, Dow Street, University of Dundee, Dundee DD1 5EH, Scotland, U.K.
authors.forename: Sambit Kumar
authors.initials: SK
authors.lastname: Nanda
authors.affiliation: MRC Protein Phosphorylation and Ubiquitylation Unit, College of Life Sciences, Dow Street, University of Dundee, Dundee DD1 5EH, Scotland, U.K.
authors.forename: Marta
authors.initials: M
authors.lastname: Lopez-Pelaez
authors.affiliation: Division of Cell Signalling and Immunology, College of Life Sciences, University of Dundee, Dundee DD1 5EH, Scotland, U.K.
authors.forename: Alan
authors.initials: A
authors.lastname: Prescott
authors.affiliation: Dana Farber Cancer Institute, Harvard Medical School, Boston, MA 02115, U.S.A.
authors.forename: Nathanael
authors.initials: N
authors.lastname: Gray
authors.affiliation: MRC Protein Phosphorylation and Ubiquitylation Unit, College of Life Sciences, Dow Street, University of Dundee, Dundee DD1 5EH, Scotland, U.K. p.cohen@dundee.ac.uk.
authors.forename: Philip
authors.initials: P
authors.lastname: Cohen
mesh_terms: D000818:Animals; D050256:Antimitotic Agents / Q000494:pharmacology; D018797:Cell Cycle Proteins; D002461:Cell Line, Transformed; D003713:Dendritic Cells / Q000187:drug effects / Q000276:immunology / Q000378:metabolism*; D006801:Humans; D050838:Interferon Regulatory Factor-3 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D016899:Interferon-beta / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D008024:Ligands; D008264:Macrophages / Q000187:drug effects / Q000276:immunology / Q000378:metabolism*; D051379:Mice; D009687:Nuclear Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011401:Promoter Regions, Genetic / Q000187:drug effects; D020033:Protein Isoforms / Q000037:antagonists & inhibitors / Q000378:metabolism; D016755:Proto-Oncogene Proteins c-jun / Q000037:antagonists & inhibitors / Q000378:metabolism; D011621:Pteridines / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects; D051199:Toll-Like Receptor 7 / Q000378:metabolism; D051217:Toll-Like Receptor 9 / Q000378:metabolism; D014157:Transcription Factors / Q000037:antagonists & inhibitors / Q000378:metabolism*; D014158:Transcription, Genetic / Q000187:drug effects; D000092468:Bromodomain Containing Proteins
chemical_list: D050256:Antimitotic Agents; D018797:Cell Cycle Proteins; D050838:Interferon Regulatory Factor-3; D016899:Interferon-beta; D008024:Ligands; D009687:Nuclear Proteins; D020033:Protein Isoforms; D016755:Proto-Oncogene Proteins c-jun; D011621:Pteridines; D051199:Toll-Like Receptor 7; D051217:Toll-Like Receptor 9; D014157:Transcription Factors; C518477:BI 2536; C441289:BRD4 protein, human; D000092468:Bromodomain Containing Proteins; C486694:Brd4 protein, mouse
keywords: BI-2536; Polo-like kinase; Toll-like receptor; bromodomain and extra-terminal; histone; interferon