EXPRESSION OF CYTOCHROME-P450 1A1, AN ESTROGEN HYDROXYLASE, IN OVARIAN GRANULOSA-CELLS IS DEVELOPMENTALLY-REGULATED

In this paper we report the analysis of porcine ovarian granulosa cell s for the expression of several known hepatic estrogen hydroxylase RNA s. Of the P450s examined, only CYP 1A1 RNA was detected. Accordingly, the regulation of this mRNA was studied. The RNA for CYP 1A1 was drama tically and completely induced within 2 hours after exposure of immort alized granulosa cells to 3-methylcholanthrene (3MC) and expression co uld be inhibited with 10 mu M phorbol myristate acetate. This message was also inducible by 3MC in cultured primary granulosa cells isolated from immature and developing follicles. Dexamethasone increased the r elative expression of CYP 1A1 RNA in 3MC treated cells. In the absence of 3MC, the CYP 1A1 message was expressed in cultured granulosa cells from developing but not immature follicles, indicating developmental regulation of this enzyme. Further support for developmental regulatio n was provided by studies which detected the appearance of CYP 1A1 RNA during growth of ovarian follicles in vivo. This is the first report identifying a specific P450 estrogen hydroxylase RNA in ovarian granul osa cells.