Growth Differentiation Factor 9 Is Antiapoptotic during Follicular Development from Preantral to Early Antral Stage

Abstract

Ovarian follicular atresia represents a selection process that ensures the release of only healthy and viable oocytes during ovulation. The transition from preantral to early antral stage is the penultimate stage of development in terms of gonadotropin dependence and follicle destiny (survival/growth vs. atresia). We have examined whether and how oocyte-derived growth differentiation factor 9 (GDF-9) and FSH regulate follicular development and atresia during the preantral to early antral transition, by a novel combination of in vitro gene manipulation (i.e. intraoocyte injection of GDF-9 antisense oligos) and preantral follicle culture. Injection of GDF-9 antisense suppressed basal and FSH-induced preantral follicle growth in vitro, whereas addition of GDF-9 enhanced basal and FSH-induced follicular development. GDF-9 antisense activated caspase-3 and induced apoptosis in cultured preantral follicles, a response attenuated by exogenous GDF-9. GDF-9 increased phospho-Akt content in granulosa cells of early antral follicles. Although granulosa cell apoptosis induced by ceramide was attenuated by the presence of GDF-9, this protective effect of GDF-9 was prevented by the phosphatidylinositol 3-kinase inhibitor LY294002 and a dominant negative form of Akt. Injection of GDF-9 antisense decreased FSH receptor mRNA levels in cultured follicles, a response preventable by the presence of exogenous GDF-9. The data suggest that GDF-9 is antiapoptotic in preantral follicles and protects granulosa cells from undergoing apoptosis via activation of the phosphatidylinositol 3-kinase/Akt pathway. An adequate level of GDF-9 is required for follicular FSH receptor mRNA expression. GDF-9 promotes follicular survival and growth during the preantral to early antral transition by suppressing granulosa cell apoptosis and follicular atresia.

Interaction between growth differentiation factor 9, insulin-like growth factor I and growth hormone on the in vitro development and survival of goat preantral follicles

“…In the present study, we observed a significant effect of GDF-9, IGF-I and GH alone or combined, enhancing the survival of goat preantral follicles, except when GDF-9/IGF-I and GDF-9/GH were used, since there was no synergistic effect between these compounds when combined. Orisaka et al (28) suggested that GDF-9 promotes follicular survival and growth during the preantral to early antral transition by suppressing granulosa cell apoptosis and follicular atresia. Deletion of the GDF-9 gene in mice blocked folliculogenesis at the primary stage, demonstrating the importance of this growth factor in early follicular development (29).…”

SMAD7 antagonizes key TGFβ superfamily signaling in mouse granulosa cells in vitro

“…GDF9 and BMP15 are oocyte paracrine factors whose functions in follicular development have been well elaborated (Dong et al 1996, Vitt et al 2000, Otsuka et al 2001, Yan et al 2001, Otsuka & Shimasaki 2002, Shimasaki et al 2004, Gilchrist et al 2006, Yoshino et al 2006, Sugiura et al 2007, Edwards et al 2008, Su et al 2008. GDF9 is expressed in oocytes in mice and humans (McGrath et al 1995, Aaltonen et al 1999 and plays a key role in normal follicular development (Elvin et al 1999, Orisaka et al 2006. Interestingly, our data indicated that knockdown of ALK2/3/6 ALK4/5/7 SMAD7 SMAD7 ?…”

Concentrations of bone morphogenetic protein-15 (BMP-15) and growth differentiation factor-9 (GDF-9) in follicular cysts, mono - and polyoocyte follicles in gilts

“…This balance disturbance is in turn one of the reasons of ovarian cyst formation [25]. Namely, the transition of the follicle from the preantral to early antral stage is the "penultimate" stage of development in terms of gonadotropin dependence and follicle destiny [growth versus atresia] [26]. Follicles selected for further development are thought to receive precise gonadotropic and intra-ovarian regulatory signals for survival, whereas follicular atresia is a consequence of inadequate growth support [27].…”