3β-hydroxy-5-ene steroid dehydrogenase gene expression regulation in porcine granulosa cells. I: FSH- and LH-mediated transcriptional activation.

In this report we examined the effect of FSH and LH, on the steady state levels of 3β-5-hydroxy-5-ene steroid dehydrogenase (3β-HSD) mRNA and on the 3β-HSD-gene transcriptional activation in porcine cultured granulosa cells. Exposure of granulosa cells to 100 ng/ml FSH or LH for 8 h, elevated to 3.0 and 2.5-fold respectively the levels of 3β-HSD mRNA measured by Northern blot analyses. The withdrawal of FSH and LH induced a rapid decay of the 3β-HSD levels, reaching the control values after 2 h. Re-addition of FSH and LH after 4 h withdrawal elevated the levels of 3β-HSD mRNA to 4.8 and 5.3-fold respectively. Addition of actinomycin D, to granulosa cells previously treated with FSH or LH, induced a rapid decay in the levels of 3β-HSD mRNA, reaching the control values after 2 h, with an estimated half life 1.3 and 1.2 h respectively. FSH and LH stimulated the 3β-HSD-gene transcription, measured by nuclear run-on assays, by 1.7 and 1.9-fold respectively. Addition of cholera toxin (10 ng/ml) or forskolin (10NM: ) stimulated the 3β-HSD-gene transcription by 2.15 and 2.4-fold respectively. We conclude that gonadotropins positively regulate 3β-HSD transcriptional activation and appear to have no effect on the 3β-HSD mRNA stability.