title: Mechanism of IFN-beta-mediated inhibition of IL-8 gene expression in astroglioma cells.
abstract: IL-8 is a chemokine that recruits migrating neutrophils and leukocytes to areas of inflammation. In noninflamed tissue, IL-8 expression is low but can be rapidly induced by proinflammatory cytokines. Typically, inflammation and transient IL-8 expression are beneficial. However, some diseases are characterized by excessive inflammation and high levels of IL-8. Previous studies have shown that IFN-beta can inhibit the expression of IL-8, although the mechanism is unknown. Using chromatin immunoprecipitation assays, we define the IL-8 transcriptional program in the absence or presence of inducing stimuli and/or inhibition by IFN-beta. In the absence of stimuli, the IL-8 promoter is acetylated but negatively regulated by corepressor proteins. Upon PMA stimulation, the levels of these corepressors are reduced and the promoter is rapidly bound and activated by transcription factors, including NF-kappaB p65, C/EBPbeta, and c-Fos. In addition, RNA polymerase II is recruited to the IL-8 promoter to initiate transcription. However, in the presence of both PMA and IFN-beta, there are diminished levels of histone acetylation, reduced levels of transcription factors such as NF-kappaB p65 and RNA polymerase II, and an increased presence of corepressor proteins such as histone deacetylases 1 and 3 and silencing mediator of retinoic acid and thyroid hormone receptors. IFN-gamma-inducible protein-10 and MCP-1 genes, also regulated by NF-kappaB, are unaffected by IFN-beta, and IFN-beta does not prevent the activation, nuclear migration, or binding of NF-kappaB p65 to the kappaB element of the IFN-gamma-inducible protein-10 promoter. As such, these data show that the inhibitory effects of IFN-beta are specific to the IL-8 promoter.
authors.affiliation: Department of Cell Biology, University of Alabama at Birmingham, 1918 University Boulevard, Birmingham, AL 35294, USA. snozell@uab.edu
authors.forename: Susan
authors.initials: S
authors.lastname: Nozell
authors.forename: Travis
authors.initials: T
authors.lastname: Laver
authors.forename: Kiran
authors.initials: K
authors.lastname: Patel
authors.forename: Etty N
authors.initials: EN
authors.lastname: Benveniste
mesh_terms: D000107:Acetylation; D021581:Active Transport, Cell Nucleus / Q000235:genetics / Q000276:immunology; D001254:Astrocytoma / Q000235:genetics* / Q000276:immunology* / Q000378:metabolism; D045744:Cell Line, Tumor; D004268:DNA-Binding Proteins / Q000378:metabolism; D015536:Down-Regulation / Q000235:genetics / Q000276:immunology; D005786:Gene Expression Regulation / Q000187:drug effects / Q000276:immunology*; D056284:Histone Deacetylase 1; D006655:Histone Deacetylases / Q000378:metabolism; D006657:Histones / Q000037:antagonists & inhibitors / Q000378:metabolism; D006801:Humans; D016899:Interferon-beta / Q000502:physiology*; D016209:Interleukin-8 / Q000037:antagonists & inhibitors* / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism / Q000502:physiology; D056985:Nuclear Receptor Co-Repressor 2; D011401:Promoter Regions, Genetic / Q000187:drug effects; D011485:Protein Binding / Q000276:immunology; D012333:RNA, Messenger / Q000096:biosynthesis; D012097:Repressor Proteins / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014157:Transcription Factors / Q000037:antagonists & inhibitors / Q000276:immunology / Q000378:metabolism; D015533:Transcriptional Activation / Q000276:immunology; D000099186:Histone Deacetylase 3
chemical_list: D004268:DNA-Binding Proteins; D056284:Histone Deacetylase 1; D006655:Histone Deacetylases; D006657:Histones; D016899:Interferon-beta; D016209:Interleukin-8; D016328:NF-kappa B; D056985:Nuclear Receptor Co-Repressor 2; D012333:RNA, Messenger; D012097:Repressor Proteins; D013755:Tetradecanoylphorbol Acetate; D014157:Transcription Factors; D000099186:Histone Deacetylase 3; C539130:NCOR2 protein, human; C110550:HDAC1 protein, human