Disease relevance of Gdf9

• Our previous studies demonstrated that absence of the TGF-beta family member, growth differentiation factor-9 (GDF-9), blocks ovarian folliculogenesis at the primary follicle stage leading to infertility [1].

High impact information on Gdf9

• Consistent with these findings, abnormal double-oocyte follicles, indicative of aberrant BMP-15/GDF-9 expression, were observed in GCNF(fl/fl)Zp3Cre(+) females [2].
• GDF-9 stimulated Cox2 mRNA within 2 h, and PGE(2) within 6 h; however, progesterone was not increased until 12 h after addition of GDF-9 [3].
• In addition, GDF-9 stimulates EP2 mRNA synthesis by a prostaglandin- and progesterone-independent pathway [3].
• To define the interrelationship of these factors, we used a preovulatory granulosa cell culture system in which we added recombinant GDF-9, prostaglandins, prostaglandin receptor agonists, or cyclooxygenase inhibitors [3].
• Thus, GDF-9 induces an EP2 signal transduction pathway which appears to be required for progesterone synthesis in cumulus granulosa cells [3].

Biological context of Gdf9

• Our results show that GCNF directly regulates paracrine communication between the oocyte and somatic cells by regulating the expression of BMP-15 and GDF-9, to affect female fertility [2].
• These studies demonstrate that PTX3 plays important roles in cumulus cell-oocyte interaction in the periovulatory period as a downstream protein in the GDF-9 signal transduction cascade [4].
• This demonstrates that in the absence of GDF-9, the follicles are incompetent to emit a signal that recruits theca cell precursors to surround the follicle; 2) The primary follicles of GDF-9-deficient mice demonstrate an up-regulation of kit ligand and inhibin-alpha [5].
• RNA interference evidence that growth differentiation factor-9 mediates oocyte regulation of cumulus expansion in mice [6].
• We searched the GenBank Expressed Sequence Tag (EST) database with the mouse GDF-9 cDNA sequence, and identified from a mouse 2-cell embryo library an EST cDNA that encodes a putative member of the TGF-b superfamily, and named it as GDF-9B [7].

Anatomical context of Gdf9

• After 24 h of culture in the presence of 0.5 IU/ml of FSH, cumulus shells cocultured with buffer- and Bmp15 dsRNA-injected oocytes exhibited a high degree of expansion, whereas cumulus shells cocultured with Gdf9 dsRNA-injected oocytes exhibited only limited expansion [6].
• GCNF-dependent repression of BMP-15 and GDF-9 mediates gamete regulation of female fertility [2].
• Integrin alpha(v) mRNA is most highly expressed in the granulosa cells of multilayer growing follicles, and therefore only low levels of expression are detectable in the Gdf 9 knockout ovaries [8].
• The major findings of our studies are as follows: 1) There are no detectable signals around GDF-9-deficient follicles for several theca cell layer markers [i.e. 17alpha-hydroxylase, LH receptor (LHR), and c-kit, the receptor for kit ligand] [5].
• Up-regulation of kit ligand, via signaling through c-kit on the oocyte, may be directly involved in the increased size of GDF-9-deficient oocytes and the eventual demise of the oocyte; 3) After loss of the oocyte, the cells of the GDF-9-deficient follicles remain in a steroidogenic cluster that histologically resembles small corpora lutea [5].

Associations of Gdf9 with chemical compounds

• Integrin alpha6 is highly expressed in Gdf 9 knockout ovaries, which are enriched in oocytes and primary (single layer) follicles because of a block at this stage of follicular development [8].
• Moreover, like GDF-9, GDF-9B lacks the cysteine residue needed for the covalent dimerization of several TGF-b family members [7].
• Consistent with the induction of StAR mRNA by GDF-9, recombinant GDF-9 increases granulosa cell progesterone synthesis in the absence of FSH [1].
• Using both radiolabeled thymidine incorporation and PCNA staining in vitro, we showed that recombinant GDF9 could restore the proliferation of coupling-deficient granulosa cells to the level of control cells [9].
• However, addition of PGE(2) to cultures containing both GDF-9 and NS-398 overrides the NS-398 block in progesterone synthesis [3].

Regulatory relationships of Gdf9

• Bromodomain containing 2 (Brd2) is expressed in distinct patterns during ovarian folliculogenesis independent of FSH or GDF9 action [10].
• Although BMP-15 is expressed identically to GDF-9, its role in regulating ovarian function is still unknown [11].
• Our microarray analysis has identified gremlin as one of the genes up-regulated by GDF9 in cultures of granulosa cells [12].
• Growth differentiation factor 9 (GDF9) is an oocyte-expressed member of the transforming growth factor beta (TGF-beta) superfamily and is required for normal ovarian follicle development and female fertility [12].
• Monoclonal neutralizing antibody-GDF9-53 attenuated GDF9-induced OOX HAS2 expression but not oocyte-induced HAS2 expression [13].

Other interactions of Gdf9

• Thus, Brd2 expression appears to correlate with stages of oocyte maturation, independent of FSH or GDF9 action and the subsequent disruption in normal follicle development in these models [10].
• These same expression patterns were also seen in oocytes from Gdf9(-/-) and Fshb(-/-) mice [10].
• Knockout of pentraxin 3, a downstream target of growth differentiation factor-9, causes female subfertility [4].
• Based on knockout mouse models BMP-6 does not play an essential role in ovarian function, but GDF-9 is absolutely required for preantral follicle development [11].
• To investigate the role of GDF9 in cumulus expansion, two endpoints were used to evaluate cumulus expansion: Has2 and Ptgs2 mRNA levels were measured in cumulus cells using real-time RT-PCR, and assessment of cumulus expansion was undertaken morphologically [6].

Analytical, diagnostic and therapeutic context of Gdf9

• In a mouse mural granulosa cell (MGC) bioassay, mAb-GDF9-53 completely abolished the mitogenic effects of GDF9, but had no effect on TGFbeta1 or activin A-stimulated MGC proliferation [14].
• Using in situ hybridization analysis, we demonstrate that GDF-9B and GDF-9 mRNAs are co-localized in the oocyte [7].
• Northern blot hybridization analyses of mouse ovaries revealed a single transcript of approximately 4.0 kilobases (kb) for GDF-9B and of 2.0 kb for GDF-9 [7].
• Based on epitope mapping and bioassays, a GDF9 neutralizing antibody, mAb-GDF9-53, was characterized with very low cross-reactivity with related transforming growth factor (TGF)beta superfamily members, including BMP15 (also called GDF9B) [14].
• As predicted by sequence alignments and modeling, the antibody detected recombinant GDF9, but not BMP15 in a Western blot and GDF9 protein in oocyte extract and oocyte-conditioned medium [14].

References