Integration of prolactin and glucocorticoid signaling at the beta-casein promoter and enhancer by ordered recruitment of specific transcription factors and chromatin modifiers.
Lactogenic hormone regulation of beta-casein gene expression in mammary epithelial cells provides an excellent system in which to perform kinetic studies of chromatin remodeling and transcriptional activation. Using HC11 cells as a model, we have investigated the effects of prolactin (Prl) and glucocorticoids both singly and in combination at different time points after hormone treatment. Using chromatin immunoprecipitation analysis, we have determined the dynamics of assembly and disassembly of signal transducer and activator of transcription 5, glucocorticoid receptor, CCAAT enhancer binding protein beta, and Ying Yang-1 at the hormonally activated beta-casein proximal promoter as well as the distal mouse beta-casein enhancer located approximately -6 kb upstream of the transcription start site. Prl alone resulted in a rapid recruitment of both signal transducer and activator of transcription 5 and histone deacetylase 1 to the beta-casein promoter and enhancer, and reciprocally the dissociation of Ying Yang-1 from the proximal promoter. In addition, we have examined the recruitment of coactivator p300 and determined chromatin acetylation status as a function of hormonal treatment. Finally, we have established the time course of RNA polymerase II and phospho-RNA polymerase II accumulation at the beta-casein promoter and enhancer after stimulation with hydrocortisone and Prl. Although glucocorticoids alone led to a rapid increase in histone H3 acetylation, treatment with both hormones was required for stable association of p300 and phospho-RNA polymerase II at both the promoter and enhancer. Collectively, these data suggest a model for the assembly of a multiprotein complex that helps to define how the signaling pathways controlled by these lactogenic hormones are integrated to regulate beta-casein gene expression.
Kabotyanski
Elena B
EB
Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas 77030, USA.
Huetter
Markus
M
Xian
Wa
W
Rijnkels
Monique
M
Rosen
Jeffrey M
JM
D000818:Animals; D022782:CCAAT-Enhancer-Binding Protein-beta / Q000378:metabolism; D002364:Caseins / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D042002:Chromatin Assembly and Disassembly / Q000502:physiology*; D047369:Chromatin Immunoprecipitation; D017931:DNA Primers; D004742:Enhancer Elements, Genetic / Q000235:genetics; D005786:Gene Expression Regulation / Q000502:physiology*; D008321:Mammary Glands, Animal / Q000166:cytology / Q000378:metabolism*; D051379:Mice; D008954:Models, Biological; D011388:Prolactin / Q000378:metabolism*; D011401:Promoter Regions, Genetic / Q000235:genetics; D012319:RNA Polymerase II / Q000378:metabolism; D011965:Receptors, Glucocorticoid / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D050799:STAT5 Transcription Factor / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*; D014157:Transcription Factors / Q000378:metabolism*; D050986:YY1 Transcription Factor / Q000378:metabolism
D022782:CCAAT-Enhancer-Binding Protein-beta; D002364:Caseins; D017931:DNA Primers; D011965:Receptors, Glucocorticoid; D050799:STAT5 Transcription Factor; D014157:Transcription Factors; D050986:YY1 Transcription Factor; C494699:Yy1 protein, mouse; D011388:Prolactin; D012319:RNA Polymerase II