Liver receptor homolog-1 regulates the expression of steroidogenic acute regulatory protein in human granulosa cells.
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.
Kim
Joung Woul
JW
Division of Reproductive Endocrinology and Infertility, Department of Obstetrics and Gynecology, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9032, USA.
Peng
Noel
N
Rainey
William E
WE
Carr
Bruce R
BR
Attia
George R
GR
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
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