title: Positive regulatory domain I (PRDM1) and IRF8/PU.1 counter-regulate MHC class II transactivator (CIITA) expression during dendritic cell maturation.
abstract: Dendritic cells (DCs) are key mediators of immune function through robust and tightly regulated presentation of antigen in the context of the MHC Class II. MHC Class II expression is controlled by the transactivator CIITA. CIITA expression in conventional DCs is uniquely dependent on an uncharacterized myeloid cell-specific promoter, CIITApI. We now identify in vivo the promoter structure and factors regulating CIITApI. In immature DCs transcription requires binding of PU.1, IRF8, NFκB, and Sp1 to the promoter. PU.1 binds independently at one site and in a required heterodimer with IRF8 at a composite element. DCs from IRF8-null mice have an unoccupied CIITApI promoter that can be rescued by reconstitution with IRF8 in vitro. Furthermore, mutation of either PU.1 site or the IFR8 site inhibits transcriptional activation. In vivo footprinting and chromatin immunoprecipitation reveals that DC maturation induces complete disassociation of the bound activators paralleled by recruitment of PRDM1/Blimp-1 to the promoter. PRDM1 is a transcriptional repressor with essential roles in B cells, T cells, NK cells, and DCs. We show that PRDM1 co-repressors, G9a and HDAC2, are recruited to CIITApI, leading to a loss of histone acetylation and acquisition of histone H3K9 dimethylation and heterochromatin protein 1γ (HP1γ). PRDM1 binding also blocks IRF8-mediated activation dependent on the PU.1/IRF composite element. Together these findings reveal the mechanisms regulating CIITA and, thus, antigen presentation in DCs, demonstrating that PRDM1 and IRF8/PU.1 counter-regulate expression. The activity of PRDM1 in silencing all three cell type-specific CIITA promoters places it as a central regulator of antigen presentation.
authors.affiliation: From the H. Lee Moffitt Cancer Center and Research Institute, Department of Molecular Medicine and Department of Oncologic Sciences, University of South Florida, Tampa, Florida 33612.
authors.forename: Matthew A
authors.initials: MA
authors.lastname: Smith
authors.affiliation: From the H. Lee Moffitt Cancer Center and Research Institute, Department of Molecular Medicine and Department of Oncologic Sciences, University of South Florida, Tampa, Florida 33612.
authors.forename: Gabriela
authors.initials: G
authors.lastname: Wright
authors.affiliation: From the H. Lee Moffitt Cancer Center and Research Institute, Department of Molecular Medicine and Department of Oncologic Sciences, University of South Florida, Tampa, Florida 33612.
authors.forename: Jian
authors.initials: J
authors.lastname: Wu
authors.affiliation: the Laboratory of Molecular Growth Regulation, NICHD, National Institutes of Health, Bethesda, Maryland 20892.
authors.forename: Prafullakumar
authors.initials: P
authors.lastname: Tailor
authors.affiliation: the Laboratory of Molecular Growth Regulation, NICHD, National Institutes of Health, Bethesda, Maryland 20892.
authors.forename: Keiko
authors.initials: K
authors.lastname: Ozato
authors.affiliation: From the H. Lee Moffitt Cancer Center and Research Institute, Department of Molecular Medicine and Department of Oncologic Sciences, University of South Florida, Tampa, Florida 33612.
authors.forename: Xianghong
authors.initials: X
authors.lastname: Chen
authors.affiliation: From the H. Lee Moffitt Cancer Center and Research Institute, Department of Molecular Medicine and Department of Oncologic Sciences, University of South Florida, Tampa, Florida 33612.
authors.forename: Sheng
authors.initials: S
authors.lastname: Wei
authors.affiliation: the Department of Medical Education, Texas Tech University Health Sciences Center, Paul L. Foster School of Medicine, El Paso, Texas 79905, and.
authors.forename: Janet F
authors.initials: JF
authors.lastname: Piskurich
authors.affiliation: the Department of Immunology, Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina 27599.
authors.forename: Jenny P-Y
authors.initials: JP
authors.lastname: Ting
authors.affiliation: From the H. Lee Moffitt Cancer Center and Research Institute, Department of Molecular Medicine and Department of Oncologic Sciences, University of South Florida, Tampa, Florida 33612,. Electronic address: ken.wright@moffitt.org.
authors.forename: Kenneth L
authors.initials: KL
authors.lastname: Wright
mesh_terms: D000107:Acetylation; D000818:Animals; D017951:Antigen Presentation / Q000502:physiology*; D003713:Dendritic Cells / Q000166:cytology / Q000276:immunology / Q000378:metabolism*; D006649:Histocompatibility Antigens / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D056464:Histone Deacetylase 2 / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D011495:Histone-Lysine N-Methyltransferase / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D006657:Histones / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D006801:Humans; D050835:Interferon Regulatory Factors / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D009687:Nuclear Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D000074462:Positive Regulatory Domain I-Binding Factor 1; D017434:Protein Structure, Tertiary; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D012097:Repressor Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D020218:Response Elements / Q000502:physiology; D015534:Trans-Activators / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D014158:Transcription, Genetic / Q000502:physiology; D000099185:Interferon Regulatory Factor-8; D000099232:Proto-Oncogene Protein Spi-1
chemical_list: D006649:Histocompatibility Antigens; D056464:Histone Deacetylase 2; D011495:Histone-Lysine N-Methyltransferase; D006657:Histones; D050835:Interferon Regulatory Factors; D009687:Nuclear Proteins; D000074462:Positive Regulatory Domain I-Binding Factor 1; D011518:Proto-Oncogene Proteins; D012097:Repressor Proteins; D015534:Trans-Activators; D014157:Transcription Factors; D000099185:Interferon Regulatory Factor-8; D000099232:Proto-Oncogene Protein Spi-1; C083728:MHC class II transactivator protein; C513258:Prdm1 protein, mouse; C087042:PRDM1 protein, human; C445405:EHMT2 protein, human; C533711:G9a protein, mouse; C533423:HDAC2 protein, human; C533424:Hdac2 protein, mouse