INDUCTION OF CYCLOOXYGENASE-2 AND PROSTAGLANDIN-F2-ALPHA RECEPTOR EXPRESSION BY INTERLEUKIN-1-BETA IN CULTURED HUMAN GRANULOSA-LUTEAL CELLS

Prostanoids are important regulators of ovarian function, especially d uring ovulation and luteolysis. Cyclooxygenase (Cox) is the rate-limit ing enzyme in conversion of arachidonic acid to prostanoids. We have e xamined the expression and regulation of the inducible Cox isoform (Co x-2) and of the receptor for PGF(2 alpha) (FP) in human granulosa cell s obtained from women undergoing oocyte retrieval for in vitro fertili zation. Freshly isolated granulosa cells express Cox-2 and FP receptor messenger RNAs (mRNAs). FP receptor mRNA is also expressed in culture d human granulosa-luteal (GL) cells, but Cox-2 transcripts are express ed only upon induction. Interleukin-1 beta (IL-1 beta) elevated Cox-2 mRNA steady state levels in a concentration-dependent manner, and kine tic studies showed that Cox-2 mRNA levels were already induced at the 2 h point and returned to the basal level after incubation for 24 h. T he protein synthesis inhibitor, cycloheximide, induced Cox-2 mRNA expr ession and potentiated the effect of IL-1 beta. Degradation of Cox-2 m RNA was inhibited by IL-1 beta, which suggests regulation at the postt ranscriptional level. IL-1 beta also induced the expression of Cox-2 p rotein, as detected by immunofluorescence staining using Cox-2-specifi c polyclonal antibodies. Further, IL-1 beta-induced synthesis of prost anoids was blocked by a Cox-2-specific inhibitor, NS-398. In addition, hCG induced Cox-2 mRNA expression and potentiated the effect of IL-1 beta. However, in contrast to the rapid and transient effect of IL-1 b eta on Cox-2 mRNA, the effect of hCG followed slower kinetics. We have previously shown that hCG induces expression of human FP receptor mRN A in cultured human GL cells. We now show that IL-1 beta induces FP re ceptor mRNA in a time-and concentration-dependent manner. Our data sug gest that Cox-2 and FP receptor are coexpressed in freshly isolated hu man granulosa cells and that their expression is up-regulated by IL-1 beta and hCG in cultured human GL cells.