Synergy between deacetylase inhibitors and IL-1beta in activation of the serum amyloid A2 gene promoter.
Butyrate (NaBu) regulates intestinal inflammatory gene expression in part through inhibition of deacetylase activity, but the exact mechanisms involved remain to be determined. In this study, we showed by Northern blot a synergistic induction of the acute phase protein gene SAA2 with a combination of deacetylase inhibitors (Trichostatin A or NaBu) and IL-1beta in the colon carcinoma cell line Caco-2. While the NF-kappa B DNA-binding site was essential for SAA2 regulation by IL-1beta and deacetylase inhibitors, the C/EBP DNA-binding site modulated SAA2 expression levels, as assessed by transient transfection assays and mutagenesis studies. NaBu was sufficient to induce SAA2 expression after transient treatment with IL-1beta and, conversely, IL-1beta induced SAA2 after transient treatment with NaBu. These data suggest that pretreatment with either NaBu or IL-1beta predisposes the SAA2 promoter to further stimulation. Indeed, both NaBu and IL-1beta led to increased recruitment of NF-kappa B p65, C/EBPbeta, and C/EBP delta, and decreased NF-kappa B p50 and C/EBP alpha DNA-binding to the proximal SAA2 promoter, as assessed by chromatin immunoprecipitation assays. Interestingly, while IL-1beta, in contrast to NaBu, induced histone H4 acetylation, addition of IL-1beta and NaBu increased histone H4 acetylation and both C/EBPbeta and NF-kappa B p65 DNA-binding. Therefore, these results suggest that NaBu and IL- 1beta mediate SAA2 synergistic induction by establishing and maintaining similar and complementary chromatin modifications and transcription factor recruitment as well. In addition to global effects, NaBu specifically regulate gene expression, as exemplified by SAA2.
Blais
Mylène
M
CIHR Group on Functional Development and Physiopathology of the Digestive Tract, Département d'Anatomie et Biologie Cellulaire, Faculté de Médecine, Université de Sherbrooke, Sherbrooke, Québec, Canada.
Désilets
Antoine
A
Asselin
Claude
C
D001665:Binding Sites; D015152:Blotting, Northern; D002087:Butyrates / Q000378:metabolism*; D022782:CCAAT-Enhancer-Binding Protein-beta / Q000378:metabolism; D051743:CCAAT-Enhancer-Binding Protein-delta; D022762:CCAAT-Enhancer-Binding Proteins / Q000378:metabolism; D003106:Colon / Q000378:metabolism; D017931:DNA Primers; D004268:DNA-Binding Proteins / Q000378:metabolism; D024202:Electrophoretic Mobility Shift Assay; D005786:Gene Expression Regulation / Q000502:physiology*; D056572:Histone Deacetylase Inhibitors; D006657:Histones / Q000378:metabolism; D006801:Humans; D006877:Hydroxamic Acids / Q000378:metabolism*; D047468:Immunoprecipitation; D007375:Interleukin-1 / Q000378:metabolism*; D008156:Luciferases; D016297:Mutagenesis, Site-Directed; D016328:NF-kappa B / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics*; D000685:Serum Amyloid A Protein / Q000235:genetics*; D051996:Transcription Factor RelA; D014157:Transcription Factors / Q000378:metabolism; D014407:Tumor Cells, Cultured
D002087:Butyrates; D022782:CCAAT-Enhancer-Binding Protein-beta; D022762:CCAAT-Enhancer-Binding Proteins; C497252:CEBPD protein, human; D017931:DNA Primers; D004268:DNA-Binding Proteins; D056572:Histone Deacetylase Inhibitors; D006657:Histones; D006877:Hydroxamic Acids; D007375:Interleukin-1; D016328:NF-kappa B; C083772:SAA2 protein, human; D000685:Serum Amyloid A Protein; D051996:Transcription Factor RelA; D014157:Transcription Factors; D051743:CCAAT-Enhancer-Binding Protein-delta; C012589:trichostatin A; D008156:Luciferases