title: Steroidogenic factor 1 and estradiol receptor act in synergism to regulate the expression of the salmon gonadotropin II beta subunit gene.
abstract: The orphan nuclear receptor steroidogenic factor-1 (SF-1) regulates the expression of several genes involved in the reproductive function and development of the adrenal, the gonads, and the pituitary gonadotropes. It also confers the gonadotrope-specific expression of the glycoprotein hormone a subunit gene by the binding to a gonadotrope-specific element (GSE). In this study, we have shown that SF-1 transactivates the salmon gonadotropin II beta subunit (sGTHII beta) gene expression. SF-1 alone offered a slight but significant enhancement on sGTHII beta promoter activity (7.2 +/- 0.6 fold). However, it stimulated sGTHII beta gene expression dramatically (127 +/- 37 fold) when combined with the estrogen receptor (ER). This synergistic interaction was specific for sGTHII beta promoter as well as for both SF-1 and ER and was estradiol-dose dependent. 5'-Deletion studies of the sGTHII beta promoter identified two putative SF-1 binding sites (GSE) and one previously identified proximal estrogen-responsive element (pERE) at -274 bp involved in this activation. The two GSE sequences located at -354 bp (sGSE(3) and -162 bp (sGSE(2) upstream of the transcription site, although imperfect as compared with the consensus GSE, bound specifically to the in vitro-translated mouse SF-1 protein. 5'-Deletion studies, competition experiments, and site-directed mutagenesis showed that binding to pERE and GSE(2) were necessary for the SF-1/ER synergistic effect. These studies suggest that the synergistic interaction of SF-1 and ER, possibly through cooperative binding or protein-protein interaction, is essential in conferring a cell type-specific expression of the GTHII beta subunit gene.
authors.affiliation: Research Institute Hospital for Sick Children, University of Toronto, Ontario, Canada.
authors.forename: Y L
authors.initials: YL
authors.lastname: Drean
authors.forename: D
authors.initials: D
authors.lastname: Liu
authors.forename: A O
authors.initials: AO
authors.lastname: Wong
authors.forename: F
authors.initials: F
authors.lastname: Xiong
authors.forename: C L
authors.initials: CL
authors.lastname: Hew
mesh_terms: D000818:Animals; D016384:Consensus Sequence; D004268:DNA-Binding Proteins / Q000502:physiology*; D051717:Fushi Tarazu Transcription Factors; D005786:Gene Expression Regulation; D005796:Genes; D006065:Gonadotropins, Pituitary / Q000096:biosynthesis / Q000235:genetics*; D006367:HeLa Cells; D018398:Homeodomain Proteins; D006801:Humans; D051379:Mice; D016297:Mutagenesis, Site-Directed; D009928:Organ Specificity; D011401:Promoter Regions, Genetic; D018160:Receptors, Cytoplasmic and Nuclear; D011959:Receptors, Estradiol / Q000502:physiology*; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D012045:Regulatory Sequences, Nucleic Acid; D012474:Salmon / Q000235:genetics*; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D054339:Steroidogenic Factor 1; D013268:Stimulation, Chemical; D014157:Transcription Factors / Q000502:physiology*; D014158:Transcription, Genetic; D014162:Transfection
chemical_list: D004268:DNA-Binding Proteins; D051717:Fushi Tarazu Transcription Factors; D006065:Gonadotropins, Pituitary; D018398:Homeodomain Proteins; C515057:NR5A1 protein, human; D018160:Receptors, Cytoplasmic and Nuclear; D011959:Receptors, Estradiol; D011993:Recombinant Fusion Proteins; D054339:Steroidogenic Factor 1; D014157:Transcription Factors; C515058:steroidogenic factor 1, mouse