title: Liver receptor homolog-1 regulates the expression of steroidogenic acute regulatory protein in human granulosa cells.
abstract: Steroidogenic acute regulatory protein (StAR) plays a critical role in the initial step of steroid hormone synthesis. In the present study, we investigated the role of liver receptor homolog-1 (LRH-1) and dosage-sensitive sex reversal, adrenal hypoplasia congenital critical region on the X chromosome, gene 1 (DAX-1) in the regulation of StAR gene expression in human granulosa cell tumor cells. We also examined the effect of protein kinase A (PKA) signaling pathway on the expression of StAR in the presence of LRH-1 and DAX-1. Cell transfection, mutation analysis, and EMSA were performed. LRH-1 significantly induced StAR promoter activity in a concentration-dependent manner. This induction was further augmented in the presence of PKA agonist. Using deletion analysis, we demonstrated LRH-1 binding site at -105/-95. Mutation of this site resulted in a significant decrease in the StAR promoter activity. Using EMSA, the ability of this cis-element to bind LRH-1 was confirmed. DAX-1 inhibited LRH-1-stimulated StAR promoter activity in a concentration-dependent manner. This inhibition was also maintained in the presence of PKA stimulation. Our results demonstrated that LRH-1 plays a critical role in the induction of StAR gene expression. We hypothesize that LRH-1 could be the major transcription factor responsible for the rapid and significant increase in ovarian StAR gene expression after ovulation.
authors.affiliation: Division of Reproductive Endocrinology and Infertility, Department of Obstetrics and Gynecology, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9032, USA.
authors.forename: Joung Woul
authors.initials: JW
authors.lastname: Kim
authors.forename: Noel
authors.initials: N
authors.lastname: Peng
authors.forename: William E
authors.initials: WE
authors.lastname: Rainey
authors.forename: Bruce R
authors.initials: BR
authors.lastname: Carr
authors.forename: George R
authors.initials: GR
authors.lastname: Attia
mesh_terms: D045744:Cell Line, Tumor; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D057137:DAX-1 Orphan Nuclear Receptor; D004268:DNA-Binding Proteins / Q000378:metabolism; D024202:Electrophoretic Mobility Shift Assay; D005260:Female; D015870:Gene Expression; D006106:Granulosa Cell Tumor; D006801:Humans; D010051:Ovarian Neoplasms; D010053:Ovary / Q000502:physiology*; D010060:Ovulation / Q000502:physiology; D010750:Phosphoproteins / Q000235:genetics*; D011401:Promoter Regions, Genetic / Q000502:physiology; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism*; D018168:Receptors, Retinoic Acid / Q000378:metabolism; D012097:Repressor Proteins / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology; D000098682:Steroidogenic Acute Regulatory Protein
chemical_list: D057137:DAX-1 Orphan Nuclear Receptor; D004268:DNA-Binding Proteins; C539965:NR0B1 protein, human; C539966:Nr0b1 protein, mouse; C431936:Nr5a2 protein, mouse; D010750:Phosphoproteins; D018160:Receptors, Cytoplasmic and Nuclear; D018168:Receptors, Retinoic Acid; D012097:Repressor Proteins; D000098682:Steroidogenic Acute Regulatory Protein; D017868:Cyclic AMP-Dependent Protein Kinases