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Estrogen receptor‐α mediates an intraovarian negative feedback loop on thecal cell steroidogenesis via modulation of Cyp17a1 (cytochrome P450, steroid 17α‐hydroxylase/17,20 μlyase) expression
Author(s) -
Taniguchi Fuminori,
Couse John F.,
Rodriguez Karina F.,
Emmen Judith M. A.,
Poirier Donald,
Korach Kenneth S.
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fj.06-6681com
Subject(s) - endocrinology , medicine , cyp17a1 , theca , ovary , biology , aromatase , polycystic ovary , estrogen receptor alpha , testosterone (patch) , folliculogenesis , androgen receptor , estrogen receptor , chemistry , microbiology and biotechnology , insulin resistance , insulin , enzyme , biochemistry , prostate cancer , cancer , breast cancer , embryo , cryopreservation
Excess androgen synthesis by thecal cells is invariably detrimental to preovulatory follicles in the ovary and is considered a fundamental characteristic of polycystic ovary syndrome in women. Investigators have long postulated that granulosa cell‐derived estrogens modulate thecal cell steroidogenesis via a short negative‐feedback loop within the follicle. To test this hypothesis, we assessed the steroidogenic capacity of individual wild‐type (WT) and estrogen receptor‐ (ERα)‐null follicles when cultured in vitro under comparable conditions. Late‐stage ERα‐null follicles exhibited markedly increased expression of the thecal cell enzyme CYP17A1 and secreted much greater amounts of its end product, androstenedione. This phenotype was reproduced in WT follicles when exposed to an aromatase inhibitor or ER‐antagonist, and prevented when the former treatment was supplemented with an ERα‐specific agonist. ERα‐null follicles also exhibited increased testosterone synthesis due to ectopic expression of hydroxysteroid (17ß) dehydrogenase type 3 (HSD17B3), a testis‐specific androgenic enzyme. These data indicate that ER17α functions within thecal cells to negatively modulate the capacity for androgen synthesis by repressing Cyp17a1 expression, and the biological activity of androgens produced by inhibiting Hsd17b3 expression. Hence, these findings provide novel evidence of an intraovarian ERα function that may be critical to the latter stages of folliculogenesis and overall ovarian function.—Taniguchi, F., Couse, J. F., Rodriguez, K. F., Emmen, J. M. A., Poirier. D., Korach, K. S. Estrogen receptor‐17α mediates an intraovarian negative feedback loop on thecal cell steroidogenesis via modulation of CYP17A1 (cytochrome P450, steroid 17α‐hydroxylase/17,20 μlyase) expression FASEB J. 21, 586 −595 (2007)