Interleukin-10 inhibits interleukin-12 p40 gene transcription by targeting a late event in the activation pathway.
Interleukin-10 (IL-10) is a potent anti-inflammatory cytokine that suppresses the induction of proinflammatory cytokine genes, including the IL-12 p40 gene. Despite considerable effort examining the effect of IL-10 on specific transcription factors and signaling molecules, the mechanism by which IL-10 inhibits gene transcription has remained elusive. To provide a different perspective to this problem, we examined the effect of IL-10 on molecular events occurring at the endogenous IL-12 p40 locus in lipopolysaccharide-stimulated peritoneal macrophages. IL-10 abolished recruitment of RNA polymerase II to the p40 promoter. However, it only modestly reduced binding of C/EBPbeta, as monitored by genomic footprinting and chromatin immunoprecipitation. It also had little effect on NF-kappaB complexes that are critical for p40 induction. A substantial reduction in nucleosome remodeling at the p40 promoter was observed, but the magnitude of this reduction appeared insufficient to account for the strong inhibition of transcription. Finally, a lipopolysaccharide-inducible DNase I hypersensitive site identified 10 kb upstream of the start site was unaffected by IL-10. Thus, despite a dramatic reduction in p40 transcription, several events required for activation of the endogenous p40 gene occurred relatively normally. These findings suggest that IL-10 blocks one or more events that occur after p40 locus decondensation and nucleosome remodeling and after, or in parallel with, the binding of a subset of p40 transcriptional activators.
Howard Hughes Medical Institute and Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, California 90095-1662, USA.
Liang
L
Zhou
Aaron A
AA
Nazarian
Stephen T
ST
Smale
D000818:Animals; D001483:Base Sequence; D001854:Bone Marrow Cells / Q000187:drug effects / Q000276:immunology / Q000378:metabolism; D022782:CCAAT-Enhancer-Binding Protein-beta / Q000378:metabolism; D018076:DNA, Complementary / Q000235:genetics / Q000378:metabolism; D003850:Deoxyribonuclease I; D066298:In Vitro Techniques; D016753:Interleukin-10 / Q000494:pharmacology*; D018664:Interleukin-12 / Q000235:genetics*; D053762:Interleukin-12 Subunit p40; D017737:Macrophages, Peritoneal / Q000187:drug effects / Q000276:immunology / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D016328:NF-kappa B / Q000378:metabolism; D009707:Nucleosomes / Q000187:drug effects / Q000378:metabolism; D011401:Promoter Regions, Genetic; D021122:Protein Subunits / Q000235:genetics*; D012319:RNA Polymerase II / Q000378:metabolism; D011994:Recombinant Proteins / Q000494:pharmacology; D014158:Transcription, Genetic / Q000187:drug effects
D022782:CCAAT-Enhancer-Binding Protein-beta; D018076:DNA, Complementary; D053762:Interleukin-12 Subunit p40; D016328:NF-kappa B; D009707:Nucleosomes; D021122:Protein Subunits; D011994:Recombinant Proteins; D016753:Interleukin-10; D018664:Interleukin-12; D012319:RNA Polymerase II; D003850:Deoxyribonuclease I