title: Differential regulation of native estrogen receptor-regulatory elements by estradiol, tamoxifen, and raloxifene.
abstract: Estrogen receptors (ERs) regulate gene transcription by interacting with regulatory elements. Most information regarding how ER activates genes has come from studies using a small set of target genes or simple consensus sequences such as estrogen response element, activator protein 1, and Sp1 elements. However, these elements cannot explain the differences in gene regulation patterns and clinical effects observed with estradiol (E(2)) and selective estrogen receptor modulators. To obtain a greater understanding of how E(2) and selective estrogen receptor modulators differentially regulate genes, it is necessary to investigate their action on a more comprehensive set of native regulatory elements derived from ER target genes. Here we used chromatin immunoprecipitation-cloning and sequencing to isolate 173 regulatory elements associated with ERalpha. Most elements were found in the introns (38%) and regions greater than 10 kb upstream of the transcription initiation site (38%); 24% of the elements were found in the proximal promoter region (<10 kb). Only 11% of the elements contained a classical estrogen response element; 23% of the elements did not have any known response elements, including one derived from the naked cuticle homolog gene, which was associated with the recruitment of p160 coactivators. Transfection studies found that 80% of the 173 elements were regulated by E(2), raloxifene, or tamoxifen with ERalpha or ERbeta. Tamoxifen was more effective than raloxifene at activating the elements with ERalpha, whereas raloxifene was superior with ERbeta. Our findings demonstrate that E(2), tamoxifen, and raloxifene differentially regulate native ER-regulatory elements isolated by chromatin immunoprecipitation with ERalpha and ERbeta.
authors.affiliation: Department of Obstetrics, Center for Reproductive Sciences, Cellular and Molecular Pharmacology, University of California-San Francisco, San Francisco, CA 94143-0556, USA.
authors.forename: Nitzan
authors.initials: N
authors.lastname: Levy
authors.forename: Dierdre
authors.initials: D
authors.lastname: Tatomer
authors.forename: Candice B
authors.initials: CB
authors.lastname: Herber
authors.forename: Xiaoyue
authors.initials: X
authors.lastname: Zhao
authors.forename: Hui
authors.initials: H
authors.lastname: Tang
authors.forename: Toby
authors.initials: T
authors.lastname: Sargeant
authors.forename: Lonnele J
authors.initials: LJ
authors.lastname: Ball
authors.forename: Jonathan
authors.initials: J
authors.lastname: Summers
authors.forename: Terence P
authors.initials: TP
authors.lastname: Speed
authors.forename: Dale C
authors.initials: DC
authors.lastname: Leitman
mesh_terms: D001665:Binding Sites / Q000235:genetics; D045744:Cell Line, Tumor; D047369:Chromatin Immunoprecipitation; D019295:Computational Biology; D004958:Estradiol / Q000494:pharmacology*; D047628:Estrogen Receptor alpha / Q000235:genetics / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D007438:Introns / Q000235:genetics; D008156:Luciferases / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics; D020849:Raloxifene Hydrochloride / Q000494:pharmacology*; D020218:Response Elements / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D020845:Selective Estrogen Receptor Modulators / Q000494:pharmacology; D013629:Tamoxifen / Q000494:pharmacology*; D014162:Transfection
chemical_list: D047628:Estrogen Receptor alpha; D020845:Selective Estrogen Receptor Modulators; D013629:Tamoxifen; D020849:Raloxifene Hydrochloride; D004958:Estradiol; D008156:Luciferases