Differential role of PR-A and -B isoforms in transcription regulation of human GnRH receptor gene

Mol Endocrinol. 2001 Dec;15(12):2078-92. doi: 10.1210/mend.15.12.0739.

Abstract

The presence of progesterone response element (PRE) in the 5'-flanking region of the human GnRH receptor (GnRHR) suggests the possible regulation of this gene by progesterone (P). In the present study, we examined the effects of P in transcriptional regulation of human GnRHR gene expression at the pituitary and placenta levels since the GnRHR has been detected in both tissues. By the use of transient transfection assays, a differential regulation of human GnRHR promoter activity by P was observed. P treatment resulted in a decrease in promoter activity in the pituitary alphaT3-1 cells, suggesting a P-mediated inhibitory action. Interestingly, P is found to have a stimulatory role at the placental expression of this gene. Addition of RU486 to, or inhibition of endogenous P production by, the placental JEG-3 cells leads to a decrease in promoter activity, which is reversed by the replacement of P. Further studies have identified a putative PRE, namely human GR-PRE (located between -535 and -521, related to translation start site), that may be responsible for the P action since the mutation of these motifs reversed the P-mediated effects. The binding of PR to this element is confirmed by antibody supershift assays. The physiological effects of P are mediated through two PR isoforms, namely PR-A and PR-B. In the present study, overexpression of human PR-A resulted in a decrease in human promoter activity in both pituitary and placental cells. Interestingly, overexpression of PR-B exhibits a cell-dependent transcriptional activity, whereby it functions as a transcription activator in the placenta but as a transcription repressor in the pituitary. In summary, our results demonstrated a differential usage of PR-A and PR-B in transcriptional regulation of human GnRHR gene expression by P at the pituitary and placenta levels.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aminoglutethimide / pharmacology
  • Animals
  • Blotting, Western
  • Dexamethasone / pharmacology
  • Enzyme Inhibitors / pharmacology
  • Female
  • Gene Expression Regulation / physiology*
  • Glucocorticoids / pharmacology
  • Hormone Antagonists / pharmacology
  • Humans
  • Mice
  • Mifepristone / pharmacology
  • Mutagenesis, Site-Directed
  • Placenta / metabolism
  • Placenta / physiology
  • Pregnancy
  • Progesterone / pharmacology
  • Protein Isoforms
  • Receptors, LHRH / analysis
  • Receptors, LHRH / biosynthesis
  • Receptors, LHRH / genetics*
  • Receptors, Progesterone / physiology*
  • Transcription, Genetic / physiology
  • Transfection
  • Tumor Cells, Cultured

Substances

  • Enzyme Inhibitors
  • Glucocorticoids
  • Hormone Antagonists
  • Protein Isoforms
  • Receptors, LHRH
  • Receptors, Progesterone
  • progesterone receptor A
  • progesterone receptor B
  • Aminoglutethimide
  • Mifepristone
  • Progesterone
  • Dexamethasone