title: Cross talk in hormonally regulated gene transcription through induction of estrogen receptor ubiquitylation.
abstract: Estrogen tightly regulates the levels of circulating gonadotropins, but a direct effect of estrogen receptor alpha (ERalpha) on the mammalian LHbeta gene has remained poorly defined. We demonstrate here that ERalpha can associate with the LHbeta promoter through interactions with Sf-1 and Pitx1 without requiring an estrogen response element (ERE). We show that gonadotropin-releasing hormone (GnRH) promotes ERalpha ubiquitylation and also degradation while stimulating expression of ubc4. GnRH also increases the association and lengthens the cycling time of ERalpha on the LHbeta promoter. The ERalpha association and transactivation of the LHbeta gene, as well as ERalpha degradation, are increased following ubc4 overexpression, while the effects of GnRH are abated following ubc4 knockdown. Our results indicate that ERalpha ubiquitylation and subsequent transactivation of the LHbeta gene can be induced by increasing the levels of the E2 enzyme as a result of signaling by an extracellular hormone, thus providing a new form of cross talk in hormonally stimulated regulation of gene expression.
authors.affiliation: Functional Genomics Laboratories, Department of Biological Sciences, National University of Singapore.
authors.forename: Min
authors.initials: M
authors.lastname: Luo
authors.forename: Mingshi
authors.initials: M
authors.lastname: Koh
authors.forename: Jiajun
authors.initials: J
authors.lastname: Feng
authors.forename: Qiang
authors.initials: Q
authors.lastname: Wu
authors.forename: Philippa
authors.initials: P
authors.lastname: Melamed
mesh_terms: D000818:Animals; D015153:Blotting, Western; D019556:COS Cells; D002843:Chromatin / Q000378:metabolism; D047369:Chromatin Immunoprecipitation; D004268:DNA-Binding Proteins / Q000378:metabolism; D005786:Gene Expression Regulation; D007987:Gonadotropin-Releasing Hormone / Q000378:metabolism; D018398:Homeodomain Proteins / Q000378:metabolism; D006728:Hormones / Q000378:metabolism*; D047468:Immunoprecipitation; D008024:Ligands; D051379:Mice; D008954:Models, Biological; D008957:Models, Genetic; D009693:Nucleic Acid Hybridization; D051761:Paired Box Transcription Factors; D010957:Plasmids / Q000378:metabolism; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic; D018160:Receptors, Cytoplasmic and Nuclear; D011960:Receptors, Estrogen / Q000378:metabolism*; D020218:Response Elements; D054339:Steroidogenic Factor 1; D013997:Time Factors; D014157:Transcription Factors / Q000378:metabolism; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D014162:Transfection; D020798:Two-Hybrid System Techniques; D025801:Ubiquitin / Q000378:metabolism*; D044763:Ubiquitin-Conjugating Enzymes / Q000378:metabolism
chemical_list: D002843:Chromatin; D004268:DNA-Binding Proteins; D018398:Homeodomain Proteins; D006728:Hormones; D008024:Ligands; D051761:Paired Box Transcription Factors; D018160:Receptors, Cytoplasmic and Nuclear; D011960:Receptors, Estrogen; D054339:Steroidogenic Factor 1; D014157:Transcription Factors; D025801:Ubiquitin; C101485:homeobox protein PITX1; D007987:Gonadotropin-Releasing Hormone; D044763:Ubiquitin-Conjugating Enzymes; C063109:ubiquitin-conjugating enzyme UBC4