Crucial role of estrogen receptor-α interaction with transcription coregulators in follicle-stimulating hormone and transforming growth factor β1 up-regulation of steroidogenesis in rat ovarian granulosa cells

This study was to explore estrogen receptor (ER) involvement in FSH and TGF beta 1-stimulated steroidogenesis in rat ovarian granulosa cells. We first determined the specific involvement of ER alpha and ER beta in the process, and then investigated the molecular interaction of ER alpha and transcription coregulators in FSH and TGF beta 1 up- regulation of steroidogenic gene expression. Primary culture of ovarian granulosa cells from antral follicles of gonadotropin-primed immature rats was used. Interestingly, a selective ER alpha antagonist methyl-piperidinopyrazole (MPP) [ like ER antagonist ICI-182,780 (ICI)] decreased FSH +/- TGF beta 1-stimulated progesterone production, whereas an androgen receptor antagonist hydroxyflutamide and particularly a selective ER beta antagonist 4-[2-Phenyl-5,7bis(trifluoromethyl) pyrazolo [1,5-a] pyrimidin-3-yl]phenol had no significant effect. Consistent with this, a selective ER beta agonist diarylpropionitrile (unlike 17 beta-estradiol) also had no effect on FSH +/- TGF beta 1-stimulated progesterone production. Furthermore, a selective ER alpha agonist 4,4', 4 ''-(4- Propyl-[1H]-pyrazole- 1,3,5-triyl)trisphenol (like 17 beta-estradiol) enhanced FSH-stimulated progesterone production, and this was abolished by pretreatment with MPP. Immunoblotting and chromatin immunoprecipitation analyses indicate that MPP/ICI suppression of FSH +/- TGF beta 1 action is partly attributed to the reduced ER alpha-mediated expression of Hsd3b and Cyp11a1 genes, but not steroidogenic acute regulatory protein. Furthermore, FSH +/- TGF beta 1 increased ER alpha association with histone acetylases (CBP and SRC-1) and coactivator of peroxisome proliferator-activated receptor gamma(PGC-1 alpha), and MPP/ ICI dramatically reduced these interactions. In addition, FSH +/- TGF beta 1 increased CBP, SRC-1, and PGC-beta 1 binding to Hsd3b and Cyp11a1 genes. Together, we demonstrate for the first time that ER alpha interaction with transcription coregulators, histone acetylases (CBP/SRC-1), and PGC-beta 1 is crucial to FSH and TGF beta 1-up-regulated expression of Hsd3b and Cyp11a1, and, thus, progesterone production in rat ovarian granulosa cells.