Potential regulation of GnRH gene by a steroidogenic factor-1-like protein.
Steroidogenic factor-1 (SF-1) is a member of an orphan nuclear hormone receptor superfamily. It plays a critical role in the development and function of the hypothalamic-pituitary-gonadal and adrenal axis. However, whether SF-1 can regulate transcription of gonadotrophin-releasing hormone (GnRH) gene is not known. To examine this possibility, we first over-expressed SF-1 and found that it not only decreased steady state GnRH messenger ribonucleic acid (mRNA) levels but also reduced its promoter activity in GT1-7 neurons. The inhibitory effect of SF-1 was lost when the 5'-flanking region of GnRH gene containing two distal (-1479 to -1474 bp and -1059 to -1054 bp) hexamers was deleted. Gel mobility shift assays showed that GT1-7 cell nuclear extracts contained a protein that formed a specific complex with synthetic oligonucleotides containing the two distal hexamers or a consensus SF-1 binding sequence. The migration of this complex was, however, slower than the complex formed with MA-10 cell nuclear extracts which were shown to contain a 53 kDa SF-1 protein. The addition of anti-SF-1 antibody supershifted the complex formed with MA-10, but not with GT1-7 cell nuclear extracts. The same antibody, however, detected a 60 kDa protein and immunostained nuclei of GT1-7 neurons. These results are consistent with GT1-7 neurons containing an SF-1-like protein that can bind to the distal hexamer sequences in the 5'-flanking region of rat GnRH gene to inhibit its transcription.
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Division of Basic Science Research, Department of Obstetrics and Gynecology, University of Louisville Health Sciences Center, Louisville, Kentucky 40292, USA.
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D000818:Animals; D002457:Cell Extracts; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D051717:Fushi Tarazu Transcription Factors; D005786:Gene Expression Regulation; D007987:Gonadotropin-Releasing Hormone / Q000235:genetics* / Q000378:metabolism; D018398:Homeodomain Proteins; D009474:Neurons; D009687:Nuclear Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D051381:Rats; D018160:Receptors, Cytoplasmic and Nuclear; D054339:Steroidogenic Factor 1; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic; D014162:Transfection
D002457:Cell Extracts; D004268:DNA-Binding Proteins; D051717:Fushi Tarazu Transcription Factors; D018398:Homeodomain Proteins; D009687:Nuclear Proteins; D018160:Receptors, Cytoplasmic and Nuclear; D054339:Steroidogenic Factor 1; D014157:Transcription Factors; C515060:steroidogenic factor 1, rat; D007987:Gonadotropin-Releasing Hormone