title: Role of oocyte-secreted growth differentiation factor 9 in the regulation of mouse cumulus expansion.
abstract: Oocyte-secreted factors are required for expansion of the mouse cumulus-oocyte complex, which is necessary for ovulation. Oocyte-secreted growth differentiation factor 9 (GDF9) signals through the bone morphogenetic protein receptor II and is currently the primary candidate molecule for the cumulus-expansion enabling factor. This study was conducted to determine whether GDF9 is the mouse cumulus-expansion enabling factor. Cumulus-oocyte complexes were collected from mice, and the oocyte was microsurgically removed to generate an oocytectomized (OOX) complex. OOX complexes treated with FSH alone or recombinant mouse GDF9 alone failed to expand, whereas expansion was induced in the presence of FSH by GDF9, TGFbeta1, or coculture with oocytes. A specific GDF9-neutralizing antibody, mAb-GDF9-53, neutralized the expansion of OOX complexes in response to GDF9 but not the expansion of OOX complexes cocultured with oocytes. Using real-time RT-PCR, hyaluronan synthase 2 (HAS2) mRNA expression by OOXs was up-regulated 4- to 6-fold by oocytes and GDF9. Monoclonal neutralizing antibody-GDF9-53 attenuated GDF9-induced OOX HAS2 expression but not oocyte-induced HAS2 expression. A TGFbeta antagonist neutralized TGFbeta-induced, but not oocyte-induced, expansion of OOX complexes, and when combined with monoclonal neutralizing antibody-GDF9-53 also failed to neutralize oocyte-induced expansion. Furthermore, a soluble portion of the bone morphogenetic protein receptor II extracellular domain, which is a known GDF9 antagonist, completely antagonized GDF9-induced expansion but only partially neutralized oocyte-induced expansion. This study provides further evidence that like TGFbeta, GDF9 can enable FSH-induced cumulus expansion, but more importantly, demonstrates that neither GDF9 nor TGFbeta alone, nor the two in unison, account for the critical oocyte-secreted factors regulating mouse cumulus expansion.
authors.affiliation: Research Centre for Reproductive Health, Department of Obstetrics and Gynaecology, University of Adelaide, The Queen Elizabeth Hospital, Woodville, South Australia 5011, Australia.
authors.forename: Rebecca A
authors.initials: RA
authors.lastname: Dragovic
authors.forename: Lesley J
authors.initials: LJ
authors.lastname: Ritter
authors.forename: Samantha J
authors.initials: SJ
authors.lastname: Schulz
authors.forename: Fred
authors.initials: F
authors.lastname: Amato
authors.forename: David T
authors.initials: DT
authors.lastname: Armstrong
authors.forename: Robert B
authors.initials: RB
authors.lastname: Gilchrist
mesh_terms: D000818:Animals; D000906:Antibodies / Q000494:pharmacology; D055430:Bone Morphogenetic Protein 15; D005260:Female; D005640:Follicle Stimulating Hormone / Q000378:metabolism / Q000494:pharmacology; D015870:Gene Expression / Q000502:physiology; D014453:Glucuronosyltransferase / Q000235:genetics; D055429:Growth Differentiation Factor 9; D000076002:Hyaluronan Synthases; D066298:In Vitro Techniques; D036341:Intercellular Signaling Peptides and Proteins / Q000276:immunology / Q000494:pharmacology / Q000502:physiology*; D051379:Mice; D008815:Mice, Inbred Strains; D009865:Oocytes / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D006080:Ovarian Follicle / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D010060:Ovulation / Q000502:physiology*; D011994:Recombinant Proteins / Q000494:pharmacology; D016212:Transforming Growth Factor beta / Q000037:antagonists & inhibitors / Q000378:metabolism
chemical_list: D000906:Antibodies; C525902:Bmp15 protein, mouse; D055430:Bone Morphogenetic Protein 15; C525898:Gdf9 protein, mouse; D055429:Growth Differentiation Factor 9; D036341:Intercellular Signaling Peptides and Proteins; D011994:Recombinant Proteins; D016212:Transforming Growth Factor beta; D005640:Follicle Stimulating Hormone; D014453:Glucuronosyltransferase; C491099:Has2 protein, mouse; D000076002:Hyaluronan Synthases