title: Genome-wide mapping of estrogen receptor-beta-binding regions reveals extensive cross-talk with transcription factor activator protein-1.
abstract: Estrogen signaling can occur through a nonclassical pathway involving the interaction of estrogen receptors (ER) with other transcription factors such as activator protein-1 (AP-1) and SP-1. However, there is little mechanistic understanding about this pathway, with conflicting results from in vitro investigations. In this study, we applied the ChIP-on-chip approach to identify ERbeta-binding sites on a genome-wide scale, identifying 1,457 high-confidence binding sites in ERbeta-overexpressing MCF7 breast cancer cells. Genes containing ERbeta-binding sites can be regulated by E2. Notably, approximately 60% of the genomic regions bound by ERbeta contained AP-1-like binding regions and estrogen response element-like sites, suggesting a functional association between AP-1 and ERbeta signaling. Chromatin immunoprecipitation (ChIP) analysis confirmed the association of AP-1, which is composed of the oncogenic transcription factors c-Fos and c-Jun, to ERbeta-bound DNA regions. Using a re-ChIP assay, we showed co-occupancy of ERbeta and AP-1 on chromatin. Short interfering RNA-mediated knockdown of c-Fos or c-Jun expression decreased ERbeta recruitment to chromatin, consistent with the role of AP-1 in mediating estrogen signaling in breast cancer cells. Additionally, ERalpha and ERbeta recruitment to AP-1/ERbeta target regions exhibited gene-dependent differences in response to antiestrogens. Together, our results broaden insights into ERbeta DNA-binding at the genomic level by revealing crosstalk with the AP-1 transcription factor.
authors.affiliation: Department of Biosciences and Nutrition, Novum, Karolinska Institutet, Huddinge, Sweden. chunyan.zhao@ki.se
authors.forename: Chunyan
authors.initials: C
authors.lastname: Zhao
authors.forename: Hui
authors.initials: H
authors.lastname: Gao
authors.forename: Yawen
authors.initials: Y
authors.lastname: Liu
authors.forename: Zoi
authors.initials: Z
authors.lastname: Papoutsi
authors.forename: Sadaf
authors.initials: S
authors.lastname: Jaffrey
authors.forename: Jan-Ake
authors.initials: JA
authors.lastname: Gustafsson
authors.forename: Karin
authors.initials: K
authors.lastname: Dahlman-Wright
mesh_terms: D015153:Blotting, Western; D001943:Breast Neoplasms / Q000235:genetics* / Q000378:metabolism* / Q000473:pathology; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D002843:Chromatin / Q000378:metabolism; D047369:Chromatin Immunoprecipitation; D047629:Estrogen Receptor beta / Q000235:genetics / Q000378:metabolism*; D004967:Estrogens / Q000494:pharmacology; D005260:Female; D015894:Genome, Human; D006801:Humans; D008156:Luciferases / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020218:Response Elements / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D018808:Transcription Factor AP-1 / Q000235:genetics / Q000378:metabolism*
chemical_list: D002843:Chromatin; D047629:Estrogen Receptor beta; D004967:Estrogens; D012333:RNA, Messenger; D018808:Transcription Factor AP-1; D008156:Luciferases