title: Transcription-dependent and transcription-independent nucleosome disruption induced by dioxin.
abstract: In mouse hepatoma cells, both the regulatory and the transcribed regions of the cyp1a1 gene assume a nucleosomal configuration when the gene is silent; two nucleosomes occupy specific sites at the transcriptional promoter. Activation of transcription by 2,3,7,8-tetrachlorodibenzo-p-dioxin is accompanied by changes in chromatin structure, which depend upon a functional aromatic hydrocarbon (Ah) receptor. In the transcribed region of the gene, nucleosome disruption occurs as a consequence of RNA elongation. In contrast, at the promoter, loss of positioned nucleosome sis independent of transcription and represents an event in the mechanism by which the liganded Ah receptor enhances transcriptional initiation.
authors.affiliation: Department of Pharmacology, Stanford University School of Medicine, CA 94305-5332.
authors.forename: J E
authors.initials: JE
authors.lastname: Morgan
authors.forename: J P
authors.initials: JP
authors.lastname: Whitlock
mesh_terms: D000818:Animals; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects*; D066298:In Vitro Techniques; D051379:Mice; D008836:Micrococcal Nuclease / Q000494:pharmacology; D009707:Nucleosomes / Q000648:ultrastructure*; D000072317:Polychlorinated Dibenzodioxins / Q000494:pharmacology*; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D014158:Transcription, Genetic / Q000187:drug effects; D014407:Tumor Cells, Cultured
chemical_list: D004268:DNA-Binding Proteins; D009707:Nucleosomes; D000072317:Polychlorinated Dibenzodioxins; D003577:Cytochrome P-450 Enzyme System; D008836:Micrococcal Nuclease