title: Retinoic acid mediates transcriptional repression of ovine follicle-stimulating hormone receptor gene via a pleiotropic nuclear receptor response element.
abstract: The FSH receptor (FSHR) and retinoid receptors are critical regulators of gonadal function. Unlike the latter, the FSH receptors are expressed exclusively in ovarian granulosa and testicular Sertoli cells in a developmental fashion. Toward understanding the nature of various transcription factors that direct a tissue- and stage-specific expression of the FSHR gene, we have studied FP4, one of the two footprinting regions (FP3 and FP4) mapped at -241 to -269 and -284 to -303, respectively, upstream of the transcription start site of the ovine FSHR gene. Gel mobility shift assays with FP4 probe revealed two sequence-specific DNA-protein complexes in the presence of nuclear extracts from two immortal gonadal cell lines. Antibody supershift assays demonstrated that retinoic acid receptor (RAR) was involved in the complex 1 whereas steroidogenic factor-1 (SF-1) was present in the complex 2. Mutation studies revealed that DNA binding sites for RAR and SF-1 were overlapping each other within a 19-base pair length of nucleotide sequence of FP4, and a mutation in the half RAR binding site seriously affected SF-1 binding. Reporter assays showed that FP4 conferred SF-1 transactivation as well as RAR-mediated, ligand-dependent repression. Overexpression of SF-1 in a transformed Sertoli cell line partially overcame RAR-mediated suppression. For the first time, our studies reveal a direct retinoid modulation of the gonadotropin receptor promoter and suggest a mechanism by which activators and repressors compete for composite elements providing antagonistic pathways that could modulate the expression of FSHR.
authors.affiliation: Molecular Reproduction Research Laboratory, Clinical Research Institute of Montreal, 110 Pine Avenue West, Montreal, Quebec, Canada H2W 1R7.
authors.forename: Weirong
authors.initials: W
authors.lastname: Xing
authors.forename: M Ram
authors.initials: MR
authors.lastname: Sairam
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002460:Cell Line; D002467:Cell Nucleus / Q000187:drug effects / Q000235:genetics*; D018983:DNA Footprinting; D003850:Deoxyribonuclease I / Q000737:chemistry; D015536:Down-Regulation / Q000187:drug effects; D004586:Electrophoresis; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects; D016297:Mutagenesis, Site-Directed / Q000235:genetics; D009687:Nuclear Proteins / Q000378:metabolism; D010957:Plasmids; D011401:Promoter Regions, Genetic / Q000235:genetics; D018160:Receptors, Cytoplasmic and Nuclear / Q000187:drug effects / Q000235:genetics*; D011962:Receptors, FSH / Q000235:genetics*; D018168:Receptors, Retinoic Acid / Q000187:drug effects / Q000235:genetics; D020218:Response Elements / Q000235:genetics*; D012756:Sheep; D014158:Transcription, Genetic / Q000187:drug effects; D014178:Translocation, Genetic; D014212:Tretinoin / Q000494:pharmacology*
chemical_list: D009687:Nuclear Proteins; D018160:Receptors, Cytoplasmic and Nuclear; D011962:Receptors, FSH; D018168:Receptors, Retinoic Acid; D014212:Tretinoin; D003850:Deoxyribonuclease I