Regulation of plasminogen activator inhibitor-1 and -2 messenger ribonucleic acid levels in human cumulus and granulosa-luteal cells.

Abstract

Plasminogen activators and their inhibitors have been implicated in the process of fibrinolysis, tissue remodeling, and ovulation. Epidermal growth factor (EGF), a paracrine hormone found in the human ovary, increases plasminogen activator (PA) activity and the gene expression of PA and plasminogen activator inhibitor (PAI) in human endothelial cells and human cell lines. Gonadotropins also increase PA activity and gene expression in rat preovulatory granulosa cells. We have now analyzed the gene expression of PAI-1 and PAI-2 in uncultured human cumulus cells (CC), uncultured granulosa-luteal cells (GLC), and cultured GLC obtained from preovulatory follicles of patients undergoing assisted reproductive technologies. We also studied the effects of hCG and EGF on PAI-1 and PAI-2 mRNA levels in cultured GLC; GLC were cultured in serum-free medium for various times within 24 h with or without hCG and for 6 h with or without hCG, EGF, or EGF plus hCG. Total RNAs from CC and GLC were extracted, and blot hybridizations with 32P-labeled PAI-1, PAI-2, or 28S ribosomal RNA cDNA probes were performed. Both CC and GLC expressed PAI-1 and PAI-2 genes. In GLC, steady state levels of PAI-1 mRNA levels steadily increased within 24 h of culture, whereas PAI-2 levels peaked at 6 h of culture. PAI-1 mRNA levels were not affected by hCG or EGF at 6 h of culture, but PAI-2 mRNA levels were significantly increased by EGF at 6 h of culture. These studies demonstrate that human GLC PAI-1 and PAI-2 mRNA levels are differentially regulated and suggest that EGF may be involved in modulation of the human ovarian PA system during the periovulatory period.