title: Kinetics of a gamma interferon response: expression and assembly of CIITA promoter IV and inhibition by methylation.
abstract: Chromatin immunoprecipitation assays were employed to assess the kinetics of transcription factor assembly and histone modifications that occur during gamma interferon (IFN-gamma) induction of CIITA gene expression. CIITA is the master regulator of major histocompatibility complex class II transcription. Promoter IV (PIV), the major IFN-gamma responsive promoter for CIITA expression, requires both STAT1 and IFN regulatory factor 1 (IRF-1) for induction by IFN-gamma. STAT1 binding to PIV was detected first and was accompanied by a modest acetylation of histones H3 and H4 that were associated with the region. Despite these changes, which occurred within 30 min of IFN-gamma treatment, CIITA mRNA was not detected until IRF-1 protein was synthesized and bound to its site, a process that required >120 min. In contrast to these events, fetal trophoblast-like cell lines, which are refractory to CIITA induction by IFN-gamma, failed to assemble the above factors or modify their chromatin, suggesting that accessibility to the promoter is blocked. Bisulfite sequencing of PIV showed strong hypermethylation of PIV, providing a link between methylation, chromatin structure, and factor binding. Together, this analysis provides a kinetic view of the activation of the CIITA gene in response to IFN-gamma and shows that regulatory factor assembly, chromatin modification, and gene expression proceed in discrete steps.
authors.affiliation: Department of Microbiology and Immunology, Emory University School of Medicine, Atlanta, Georgia 30322, USA.
authors.forename: Ann C
authors.initials: AC
authors.lastname: Morris
authors.forename: Guy W
authors.initials: GW
authors.lastname: Beresford
authors.forename: Myesha R
authors.initials: MR
authors.lastname: Mooney
authors.forename: Jeremy M
authors.initials: JM
authors.lastname: Boss
mesh_terms: D000107:Acetylation; D001483:Base Sequence; D002478:Cells, Cultured; D002843:Chromatin / Q000737:chemistry / Q000276:immunology / Q000378:metabolism; D018899:CpG Islands; D019175:DNA Methylation; D004268:DNA-Binding Proteins / Q000378:metabolism; D005786:Gene Expression Regulation; D005802:Genes, MHC Class II; D006657:Histones / Q000378:metabolism; D006801:Humans; D050856:Interferon Regulatory Factor-1; D007371:Interferon-gamma / Q000378:metabolism* / Q000494:pharmacology; D007700:Kinetics; D008967:Molecular Biology / Q000379:methods; D008969:Molecular Sequence Data; D009687:Nuclear Proteins; D010750:Phosphoproteins / Q000378:metabolism; D011401:Promoter Regions, Genetic; D050794:STAT1 Transcription Factor; D013447:Sulfites / Q000737:chemistry; D015534:Trans-Activators / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D014327:Trophoblasts / Q000378:metabolism
chemical_list: D002843:Chromatin; D004268:DNA-Binding Proteins; D006657:Histones; C494257:IRF1 protein, human; D050856:Interferon Regulatory Factor-1; C083728:MHC class II transactivator protein; D009687:Nuclear Proteins; D010750:Phosphoproteins; D050794:STAT1 Transcription Factor; C494079:STAT1 protein, human; D013447:Sulfites; D015534:Trans-Activators; D007371:Interferon-gamma; C042345:hydrogen sulfite