Activin regulates estrogen receptor gene expression in the mouse ovary.
Activin, a member of the transforming growth factor-beta superfamily, is an important modulator of follicle-stimulating hormone synthesis and secretion in the pituitary and plays autocrine/paracrine roles in the regulation of ovarian follicle development. From a microarray study on mouse ovarian granulosa cells, we discovered that the estrogen receptor beta (ERbeta) is inducible by activin. We previously demonstrated that estrogen suppresses activin gene expression, suggesting a feedback relationship between these two follicle-regulating hormones. The purpose of this study was to investigate fully activin A regulation of ER expression. Real time reverse transcription-PCR assays on cultured granulosa cells showed that both ERalpha and ERbeta mRNAs were induced by activin A at 4, 12, and 24 h in a dose-responsive manner. Western blots confirmed an increase in their protein levels. Consistent with increased ERalpha and ERbeta expression, activin A stimulated estradiol-induced estrogen response element promoter activity. Activin A stimulation of ER expression was a direct effect at the level of gene transcription, as it was not abolished by cycloheximide but was abolished by actinomycin D, and in transfected granulosa cells activin A stimulated ERalpha promoter activity. To investigate the effect of activin in vivo and, thus, its biological significance, we examined ER expression in inhibin transgenic mice that have decreased activin expression and discovered that these mice had decreased ERalpha and ERbeta expression in the ovary. We also found that ER mRNA levels were decreased in Müllerian inhibiting substance promoter (MIS)-Smad2 dominant negative mice that have impaired activin signaling through Smad2, and small interfering RNAs targeting Smad2 or Smad3 suppressed ERalpha promoter activation, suggesting that Smad2 and Smad3 are involved in regulating ER levels. Therefore, this study reveals an important role for activin in inducing the expression of ERs in the mouse ovary and suggests important interplay between activin and estrogen signaling.
Kipp
Jingjing L
JL
Department of Biochemistry, Molecular Biology and Cell Biology, and Center for Reproductive Science, Northwestern University, Evanston, Illinois 60208, USA.
Kilen
Signe M
SM
Woodruff
Teresa K
TK
Mayo
Kelly E
KE
D028341:Activins / Q000096:biosynthesis* / Q000235:genetics / Q000494:pharmacology; D000818:Animals; D054304:Anti-Mullerian Hormone / Q000235:genetics / Q000378:metabolism; D019898:Autocrine Communication / Q000502:physiology; D002478:Cells, Cultured; D003513:Cycloheximide / Q000494:pharmacology; D003609:Dactinomycin / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004958:Estradiol / Q000235:genetics / Q000378:metabolism; D047628:Estrogen Receptor alpha / Q000096:biosynthesis* / Q000235:genetics; D047629:Estrogen Receptor beta / Q000096:biosynthesis* / Q000235:genetics; D005260:Female; D005640:Follicle Stimulating Hormone / Q000096:biosynthesis / Q000235:genetics; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology*; D006107:Granulosa Cells / Q000166:cytology / Q000378:metabolism*; D051379:Mice; D008822:Mice, Transgenic; D019899:Paracrine Communication / Q000502:physiology; D010902:Pituitary Gland / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000502:physiology; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D051899:Smad2 Protein / Q000235:genetics / Q000378:metabolism; D051900:Smad3 Protein / Q000235:genetics / Q000378:metabolism; D013997:Time Factors; D014158:Transcription, Genetic / Q000187:drug effects / Q000502:physiology; D016212:Transforming Growth Factor beta / Q000235:genetics / Q000378:metabolism
D047628:Estrogen Receptor alpha; D047629:Estrogen Receptor beta; D011500:Protein Synthesis Inhibitors; D012333:RNA, Messenger; D051899:Smad2 Protein; C497783:Smad2 protein, mouse; D051900:Smad3 Protein; C497791:Smad3 protein, mouse; D016212:Transforming Growth Factor beta; C422405:activin A; D028341:Activins; D003609:Dactinomycin; D004958:Estradiol; D054304:Anti-Mullerian Hormone; D005640:Follicle Stimulating Hormone; D003513:Cycloheximide