Identification of novel missense mutations of GDF9 in Chinese women with polycystic ovary syndrome

GDF9His209GlnfsTer6/S428T and GDF9Q321X/S428T bi-allelic variants caused female subfertility with defective follicle enlargement

BACKGROUND

Antral follicles consist of an oocyte cumulus complex surrounding by somatic cells, including mural granulosa cells as the inner layer and theca cells as the outsider layer. The communications between oocytes and granulosa cells have been extensively explored in in vitro studies, however, the role of oocyte-derived factor GDF9 on in vivo antral follicle development remains elusive due to lack of an appropriate animal model. Clinically, the phenotype of GDF9 variants needs to be determined.

METHODS

Whole-exome sequencing (WES) was performed on two unrelated infertile women characterized by an early rise of estradiol level and defect in follicle enlargement. Besides, WES data on 1,039 women undergoing ART treatment were collected. A Gdf9Q308X/S415T mouse model was generated based on the variant found in one of the patients.

RESULTS

Two probands with bi-allelic GDF9 variants (GDF9His209GlnfsTer6/S428T, GDF9Q321X/S428T) and eight GDF9S428T heterozygotes with normal ovarian response were identified. In vitro experiments confirmed that these variants caused reduction of GDF9 secretion, and/or alleviation in BMP15 binding. Gdf9Q308X/S415T mouse model was constructed, which recapitulated the phenotypes in probands with abnormal estrogen secretion and defected follicle enlargement. Further experiments in mouse model showed an earlier expression of STAR in small antral follicles and decreased proliferative capacity in large antral follicles. In addition, RNA sequencing of granulosa cells revealed the transcriptomic profiles related to defective follicle enlargement in the Gdf9Q308X/S415T group. One of the downregulated genes, P4HA2 (a collagen related gene), was found to be stimulated by GDF9 protein, which partly explained the phenotype of defective follicle enlargement.

CONCLUSIONS

GDF9 bi-allelic variants contributed to the defect in antral follicle development. Oocyte itself participated in the regulation of follicle development through GDF9 paracrine effect, highlighting the essential role of oocyte-derived factors on ovarian response.

Oocyte-derived growth differentiation factor 9 suppresses the expression of CYP17A1 and androgen production in human theca cells

OBJECTIVE

To investigate the direct effect of growth differentiation factor 9 (GDF9) on androgen production in human theca cells.

DESIGN

Experimental study.

SETTING

Tertiary hospital-based research laboratory.

PATIENT(S)

Women who underwent in vitro fertilization and intracytoplasmic sperm injections at our clinic were included in this study.

INTERVENTION(S)

Primary cultured human theca cells from women undergoing in vitro fertilization and intracytoplasmic sperm injection treatment were treated with GDF9, an activin receptor-like kinase 5 (ALK5) inhibitor, and a SMAD4 agonist.

MAIN OUTCOME MEASURE(S)

The expression of androgen synthesis-related genes StAR, CYP17A1, and LHCGR, levels of androstenedione and testosterone, phosphorylation of SMAD2/3, and the interaction between bone morphogenic protein-activated type II receptor and ALK5 were evaluated using reverse transcription-quantitative polymerase chain reaction, Western blot, enzyme-linked immunosorbent assays, and coimmunoprecipitation assays, respectively.

RESULT(S)

Growth differentiation factor 9 decreased StAR, CYP17A1, and LHCGR expression levels in human theca cells, which was prevented by treatment with the ALK5 inhibitor, and suppressed production of androgen in human theca cells. Growth differentiation factor 9 increased SMAD2/3 phosphorylation, and the ALK5 inhibitor also suppressed this effect. Bone morphogenic protein-activated type II receptor and ALK5 bound to each other after GDF9 stimulation. The SMAD4 agonist kartogenin also decreased messenger RNA levels of StAR and CYP17A1 and protein levels of StAR in human theca cells.

CONCLUSION(S)

Growth differentiation factor 9 can activate the bone morphogenic protein-activated type II receptor-ALK5-SMAD2/3 signaling pathway, suppress CYP17A1 expression, and decrease androgen production in human theca cells.

Enhancing differentiation of menstrual blood-derived stem cells into female germ cells using a bilayer amniotic membrane and nano-fibrous fibroin scaffold

Three-dimensional nanofiber scaffolds offer a promising method for simulating in vivo conditions within the laboratory. This study aims to investigate the influence of a bilayer amniochorionic membrane/nanofibrous fibroin scaffold on the differentiation of human menstrual blood mesenchymal stromal/stem cells (MenSCs) into female germ cells. MenSCs were isolated and assigned to four culture groups: (i) MenSCs co-cultured with granulosa cells (GCs) using the scaffold (3D-T group), (ii) MenSCs using the scaffold alone (3D-C group), (iii) MenSCs co-cultured only with GCs (2D-T group), and (iv) MenSCs without co-culture or scaffold (2D-C group). Both MenSCs and GCs were independently cultured for two weeks before co-culturing was initiated. Flow cytometry was employed to characterize MenSCs based on positive markers (CD73, CD90, and CD105) and negative markers (CD45 and CD133). Additionally, flow cytometry and immunocytochemistry were used to characterize the GCs. Differentiated MenSCs were analyzed using real-time PCR and immunostaining. The real-time PCR results demonstrated significantly higher levels of VASA expression in the 3D-T group compared to the 3D-C, 2D-T, and 2D-C groups. Similarly, the SCP3 mRNA level in the 3D-T group was notably elevated compared to the 3D-C, 2D-T, and 2D-C groups. Moreover, the expression of GDF9 was significantly higher in the 3D-T group when compared to the 3D-C, 2D-T, and 2D-C groups. Immunostaining results revealed a lack of signal for VASA, SCP3, or GDF9 markers in the 2D-T group, while some cells in the 3D-T group exhibited positive staining for all these proteins. These findings suggest that the combination of a bilayer amniochorionic membrane/nanofibrous fibroin scaffold with co-culturing GCs facilitates the differentiation of MenSCs into female germ cells.

Deconstructing a Syndrome: Genomic Insights Into PCOS Causal Mechanisms and Classification

Polycystic ovary syndrome (PCOS) is among the most common disorders in women of reproductive age, affecting up to 15% worldwide, depending on the diagnostic criteria. PCOS is characterized by a constellation of interrelated reproductive abnormalities, including disordered gonadotropin secretion, increased androgen production, chronic anovulation, and polycystic ovarian morphology. It is frequently associated with insulin resistance and obesity. These reproductive and metabolic derangements cause major morbidities across the lifespan, including anovulatory infertility and type 2 diabetes (T2D). Despite decades of investigative effort, the etiology of PCOS remains unknown. Familial clustering of PCOS cases has indicated a genetic contribution to PCOS. There are rare Mendelian forms of PCOS associated with extreme phenotypes, but PCOS typically follows a non-Mendelian pattern of inheritance consistent with a complex genetic architecture, analogous to T2D and obesity, that reflects the interaction of susceptibility genes and environmental factors. Genomic studies of PCOS have provided important insights into disease pathways and have indicated that current diagnostic criteria do not capture underlying differences in biology associated with different forms of PCOS. We provide a state-of-the-science review of genetic analyses of PCOS, including an overview of genomic methodologies aimed at a general audience of non-geneticists and clinicians. Applications in PCOS will be discussed, including strengths and limitations of each study. The contributions of environmental factors, including developmental origins, will be reviewed. Insights into the pathogenesis and genetic architecture of PCOS will be summarized. Future directions for PCOS genetic studies will be outlined.

Expression and regulation of estrogen receptor 2 and its coregulators in mouse granulosa cells

The cooperative effects of estrogen and oocyte-derived paracrine factors (ODPFs) play critical roles in the normal development of ovarian follicles; however, the mechanism underlying this cooperation has not been well studied. The present study aimed to determine whether ODPFs affect estrogen signaling by regulating the expression of estrogen receptor (ESR) and its coregulators in mouse granulosa cells. Some transcripts encoding ESR coregulators were differentially expressed between cumulus and mural granulosa cells (MGCs). The transcript levels of ESR coregulators, including nuclear receptor corepressor 1 and activator 2, in cumulus cells were significantly suppressed by ODPFs; however, they increased when cumulus cell-oocyte complexes were treated with the transforming growth factor beta receptor I inhibitor, SB431542. Moreover, MGCs exhibited significantly higher ESR2 protein and transcript levels than those in cumulus cells. ODPFs promoted Esr2 expression in cumulus cells but had no effect on that in MGCs. Overall, regulation of the expression of ESR2 and its coregulators in cumulus cells by oocytes seems to be one of the mechanisms underlying estrogen-oocyte cooperation in well-developed antral follicles in mice.

Pathophysiological mechanisms of gonadotropins- and steroid hormones-related genes in etiology of polycystic ovary syndrome

OBJECTIVES

Polycystic ovary syndrome (PCOS) is an endocrinopathy in women, which, unlike its impact on fertility and health of women, there is no clear understanding about the causal mechanisms of this pathogenesis. The aim of this review paper is to investigate the pathophysiological pathways affecting the PCOS etiology, based on functions of gonadotropins- and steroid hormones-related genes.

MATERIALS AND METHODS

Due to different hormonal and metabolic signs of this complex disorder, different hypotheses are mentioned about etiology of this syndrome. Because of the heterogeneity of the reasons given for this syndrome and the spread of the effective genes in its pathophysiology, most of genes affected by sex-related hormonal imbalances are examined for discriminative diagnosis. For this purpose, published articles and reviews dealing with genetic evaluation of PCOS in women in peer-reviewed journals in PubMed and Google Scholar databases were included in this review.

RESULTS

In previous studies, it has been well demonstrated that PCOS in some individuals have a genetic origin. Pathophysiological functions of genes are primarily responsible for the synthesis of proteins that have role in PCOS before hyperandrogenism including GnRHR, FSHβ, FSHR, LHCGR, CYP19A1, HSD17B, AR and SHBG, and their effects in PCOS of human have been confirmed.

CONCLUSION

Hormonal imbalances are the first reason mentioned in PCOS etiology, and usually characterized with menstrual irregularities in PCOS women. Hyperandrogenism and gonadotropin secretion disorders are shown in PCOS condition, which are related to steroidogenesis pathways and hypothalamic-pituitary-ovarian axis disturbances, respectively.

Molecular Aspects and Clinical Relevance of GDF9 and BMP15 in Ovarian Function

Growth and differentiation factor 9 (GDF9) and bone morphogenetic protein 15 (BMP15) are oocyte-secreted factors with a leading role in the control of ovarian function in female reproduction, modulating both the cell fate of the somatic granulosa cells and the quality and developmental competence of the egg. This short review aims to consolidate the molecular aspects of GDF9 and BMP15 and their integral actions in female fertility to understand particularly their effects on oocyte quality and fetal growth. The significant consequences of mutations in the GDF9 and BMP15 genes in women with dizygotic twins as well as the clinical relevance of these oocyte factors in the pathogenesis of primary ovarian insufficiency and polycystic ovary syndrome are also addressed.

Endometriosis-associated infertility: GDF-9, AMH, and AMHR2 genes polymorphisms

PURPOSE

The purpose of this paper is to determine whether there is a correlation between polymorphisms in the growth differentiation factor-9 (GDF-9) gene and anti-Müllerian hormone (AMH) gene and its receptor, AMHR2, and endometriosis-associated infertility.

METHODS

This is a case-control study to evaluate whether there is a correlation between polymorphisms in the GDF-9 gene (SNPs determined by direct sequencing), AMH gene, AMHR2 (both SNPs determined by genotyping using TaqMan Allelic Discrimination), and endometriosis-associated infertility. The study included 74 infertile women with endometriosis and 70 fertile women (tubal ligation) as a control group.

RESULTS

Patient age and the mean FSH levels were similar between the infertile with endometriosis and fertile without endometriosis groups. The frequency of genotypes between the groups for GDF-9 gene polymorphisms did not show statistical significance, nor did the AMHR2 gene polymorphism. However, the AMH gene polymorphism did show statistical significance, relating the polymorphic allele with infertility in endometriosis.

CONCLUSIONS

We demonstrate that an SNP in the AMH gene is associated with infertility in endometriosis, whereas several SNPs in the GDF-9 gene and the - 482A G SNP in the AMHR2 gene were found to be unrelated.

Impact of oocyte-secreted factors on its developmental competence in buffalo

Oocyte-secreted factors (OSFs) play an important role in the acquisition of oocyte developmental competence through bidirectional cross-talk between oocyte and cumulus cells via gap junctions. Thus, the present study was designed to investigate the effect of two OSFs, growth differentiation factor 9 (GDF9) and bone morphogenetic protein 15 (BMP15), on the developmental competence of buffalo oocytes derived from two different follicle sizes. Cumulus–oocyte complexes (COCs) from large follicles (LF, >6 mm) or small follicles (SF, <6 mm) were collected and matured in vitro either in the presence of GDF9 or BMP15, or both, or with the denuded oocytes (DOs) as a source of native OSFs. Cleavage and blastocyst rates were significantly (P < 0.05) higher in LF-derived than SF-derived oocytes. Cleavage and blastocyst rates were significantly higher (P < 0.05) in the DOs and the combination groups compared with the control, GDF9 alone and BMP15 alone groups, both in LF-derived and SF-derived oocytes, although the cleavage and blastocyst rates did not differ significantly (P > 0.05) between DOs and combination groups. Relative mRNA analysis revealed significantly higher (P > 0.05) expression of the cumulus cell marker genes EGFR, HAS2, and CD44 in LF-derived than SF-derived oocyte; the expression of these markers was significantly higher (P > 0.05) in DOs and combination groups, irrespective of the follicle size. These results suggested that LF-derived oocytes have a higher developmental competence than SF-derived oocytes and that supplementation of GDF9 and BMP15 modulates the developmental competence of buffalo oocytes by increasing the relative abundance of cumulus-enabling factors and thereby increasing cleavage and the quality of blastocyst production.

Effect of growth differentiation factor‑9 C447T and G546A polymorphisms on the outcomes of in vitro fertilization

Single nucleotide polymorphisms (SNPs) in the growth differentiation factor (GDF)‑9 gene are associated with premature ovarian failure, insufficient ovarian stimulation and a poor in vitro fertilization (IVF) score in women with diminished ovarian reserve. The aim of the present study was to assess the effect of C447T (rs254286) and G546A (rs10491279) SNPs on ovary stimulation response, oocyte quality, fertilization rate and outcome of clinical pregnancy in an infertile population of Polish females (n=86) treated with IVF. The present study also included a group of fertile women (n=202). The P‑trend value, calculated for the GDF‑9 C447T transition in infertile women, was statistically significant and were equal to 0.0195. A significant association of the GDF‑9 C447T SNP was observed with infertility for the C/C vs. T/T + C/T model (OR= 2.140; 95% CI=1.043‑4.393; P=0.0349). The GDF‑9 G546A SNP was significantly associated with the G/A vs. G/G model with poor ovarian stimulation (OR=9.303; 95% CI=2.568‑33.745; P=0.0008) and poor fertilization rate (OR=2.981; 95% CI=1.033‑8.607; P=0.0385). For the GDF‑9 C447T SNP, a significant association was observed between the C/C + C/T vs. T/T model and a poor ovarian stimulation response (OR=15.309; 95% CI=0.875‑267.83; P=0.0078), and a poor fertilization rate (OR=4.842; 95% CI=1.310‑17.901; P=0.0121). The present genetic evaluation revealed associations between IVF outcomes and the GDF‑9 A546G and C447T SNPs. Additionally, these results indicated that the GDF‑9 C447T SNP is a possible candidate genetic risk factor for female infertility in the Polish population.

Modifications of human growth differentiation factor 9 to improve the generation of embryos from low competence oocytes

Growth differentiation factor 9 (GDF9) is an oocyte-derived growth factor that plays a critical role in ovarian folliculogenesis and oocyte developmental competence and belongs to the TGF-β family of proteins. Recombinant human GDF9 (hGDF9) is secreted in a latent form, which in the case of the fully processed protein, has the proregion noncovalently associated with the mature region. In this study, we investigated a number of amino acid residues in the mature region of hGDF9 that are different from the corresponding residues in the mouse protein, which is not latent. We designed, expressed, and purified 4 forms of chimeric hGDF9 (M1-M4) that we found to be active in a granulosa cell bioassay. Using a porcine in vitro maturation model with inherent low developmental competence (yielding 10%-20% blastocysts), we tested the ability of the chimeric hGDF9 proteins to improve oocyte maturation and developmental competence. Interestingly, one of the chimeric proteins, M3, was able to significantly increase the level of embryo production using such low competence oocytes. Our molecular modeling studies suggest that in the case of hGDF9 the Gly(391)Arg mutation probably increases receptor binding affinity, thereby creating an active protein for granulosa cells in vitro. However, for an improvement in oocyte developmental competence, a second mutation (Ser(412)Pro), which potentially decreases the affinity of the mature region for the proregion, is also required.

A Major Gene for Bovine Ovulation Rate

Half-sib daughters sired by a bull believed to be a carrier of a major gene for high ovulation rate were evaluated for ovulation rate and genotyped in an effort to both test the hypothesis of segregation of a major gene and to map the gene’s location. A total of 131 daughters were produced over four consecutive years at a University of Wisconsin-Madison research farm. All were evaluated for ovulation rate over an average of four estrous cycles using transrectal ultrasonography. The sire and all daughters were genotyped using a 3K SNP chip and the genotype and phenotype data were used in a linkage analysis. Subsequently, daughters recombinant within the QTL region and the sire were genotyped successively with 50K and 777K SNP chips to refine the location of the causative polymorphism. Positional candidate genes within the fine-mapped region were examined for polymorphism by Sanger sequencing of PCR amplicons encompassing coding and 5’ and 3’ flanking regions of the genes. Sire DNA was used as template in the PCR reactions. Strong evidence of a major gene for ovulation rate was observed (p<1x10^-28) with the gene localized to bovine chromosome 10. Fine-mapping subsequently reduced the location to a 1.2 Mb region between 13.6 and 14.8 Mb on chromosome 10. The location identified does not correspond to that for any previously identified major gene for ovulation rate. This region contains three candidate genes, SMAD3, SMAD6 and IQCH. While candidate gene screening failed to identify the causative polymorphism, three polymorphisms were identified that can be used as a haplotype to track inheritance of the high ovulation rate allele in descendants of the carrier sire.

Association of plasma GDF-9 or GDF-15 levels with bone parameters in polycystic ovary syndrome

We aimed to determine plasma levels of growth and differentiation factor (GDF)-9 and GDF-15, and their possible association with bone turnover parameters and bone mineral density (BMD), in patients with polycystic ovary syndrome (PCOS). Forty-two obese PCOS women aged 25-35 years, 23 women with idiopathic hirsutism (IH) and 20 healthy controls matched for age and body mass index were enrolled. Anthropometric, metabolic and hormonal patterns, plasma GDF-9 and GDF-15 concentrations, bone turnover markers and BMD were measured. No significant differences were observed in bone turnover markers, BMD measurements, plasma GDF-9 and GDF-15 levels in subjects with PCOS compared with the other two groups. In the combined population of all three groups, GDF-15 concentrations were negatively correlated with osteocalcin (r = -0.317, p < 0.01). Analysis of PCOS patients showed a significant correlation of GDF-15 concentrations with age and homeostasis model assessment index (r = 0.319, p < 0.05, and r = 0.312, p < 0.05, respectively). In addition, GDF-15 concentrations were negatively correlated with osteocalcin (r = -0.395, p < 0.01) and positively correlated with urine deoxypyridinoline (r = 0.353, p < 0.05). GDF-9 did not correlate with bone markers and BMD measurements. In conclusion, plasma GDF-9 and GDF-15 levels as well as bone turnover markers and BMD measurements in subjects with PCOS (25-35 years of age) were comparable with those either in subjects with IH or in healthy controls with similar anthropometric and metabolic profiles. GDF-15 might be a marker of a crossregulation between bone and energy metabolism.

Bone morphogenetic protein 15 in the pro-mature complex form enhances bovine oocyte developmental competence

Developmental competence of in vitro matured (IVM) oocytes needs to be improved and this can potentially be achieved by adding recombinant bone morphogenetic protein 15 (BMP15) or growth differentiation factor (GDF9) to IVM. The aim of this study was to determine the effect of a purified pro-mature complex form of recombinant human BMP15 versus the commercially available bioactive forms of BMP15 and GDF9 (both isolated mature regions) during IVM on bovine embryo development and metabolic activity. Bovine cumulus oocyte complexes (COCs) were matured in vitro in control medium or treated with 100 ng/ml pro-mature BMP15, mature BMP15 or mature GDF9 +/− FSH. Metabolic measures of glucose uptake and lactate production from COCs and autofluorescence of NAD(P)H, FAD and GSH were measured in oocytes after IVM. Following in vitro fertilisation and embryo culture, day 8 blastocysts were stained for cell numbers. COCs matured in medium +/− FSH containing pro-mature BMP15 displayed significantly improved blastocyst development (57.7±3.9%, 43.5±4.2%) compared to controls (43.3±2.4%, 28.9±3.7%) and to mature GDF9+FSH (36.1±3.0%). The mature form of BMP15 produced intermediate levels of blastocyst development; not significantly different to control or pro-mature BMP15 levels. Pro-mature BMP15 increased intra-oocyte NAD(P)H, and reduced glutathione (GSH) levels were increased by both forms of BMP15 in the absence of FSH. Exogenous BMP15 in its pro-mature form during IVM provides a functional source of oocyte-secreted factors to improve bovine blastocyst development. This form of BMP15 may prove useful for improving cattle and human artificial reproductive technologies.

Effects of differing oocyte-secreted factors during mouse in vitro maturation on subsequent embryo and fetal development

PURPOSE

We hypothesised that varying native oocyte-secreted factor (OSF) exposure or using different recombinant OSF peptides would have differential effects on post-in vitro maturation (IVM) embryo and fetal development.

METHODS

Mouse cumulus oocyte complexes (COCs) were treated with the purified mature domain of GDF9 and/or BMP15 or were co-cultured with denuded oocytes (DOs) from 0 h or 3 h of IVM. DOs were matured for 3 h as either intact COCs+/-FSH before denuding, or as DOs + FSH. COCs were fertilised and blastocyst development was assessed on days 5 and 6, and either differentially stained for ICM numbers or vitrified/warmed embryos were transferred to recipients to assess implantation and fetal rates.

RESULTS

No improvement in embryo development was observed with the addition of GDF9 and/or BMP15 to IVM. In contrast, embryos derived from COCs co-cultured with DOs had significantly improved blastocyst rates and ICM numbers compared to controls (P < 0.05). The highest response was obtained when DOs were first added to COCs at 3 h of IVM, after being pre-treated (0-3 h) as COCs + FSH. Compared to control, co-culture with DOs from 3 h did not affect implantation rates but more than doubled fetal yield (21% vs 48%; P < 0.05). GDF9 Western blot analysis was unable to detect any differences in quantity or form of GDF9 (17 and 65 kDa) in extracts of DO at 0 h or 3 h.

CONCLUSIONS

This study provides new knowledge on means to improve oocyte quality in vitro which has the potential to significantly aid human infertility treatment and animal embryo production technologies.

Growth differential factor-9 inhibits testosterone production in mouse theca interstitial cells

OBJECTIVE

To explore the effect of growth differential factor-9 (GDF-9) alone on cell proliferation, cell viability, steroidogenesis, and hormone-stimulated gene expression in cultured mouse theca interstitial cells.

DESIGN

Basic research.

SETTING

University hospital.

ANIMAL(S)

Immature 3- to 4-week-old SPF KM mice obtained from the Laboratory Animal Center of Sun Yat-Sen University.

INTERVENTION(S)

Addition of GDF-9 at different dosages to primary culture of mouse theca interstitial cells.

MAIN OUTCOME MEASURE(S)

Cell number, cell viability, progesterone and testosterone levels, and hormone-stimulated gene mRNA abundance.

RESULT(S)

Growth differential factor-9 mildly increased the number of mouse theca interstitial cells and cell viability in a dose-dependent manner and mildly inhibited the production of progesterone in mouse theca interstitial cells. Administration of GDF-9 at the dosages of 200 ng/mL and 400 ng/mL resulted in a significant decrease in the testosterone level compared with the control group by 60.42% and 68.76%, respectively. Growth differential factor-9 significantly suppressed Lhcgr mRNA by 47.36%, Cyp11a1 mRNA by 62.30%, and Cyp17a1 mRNA by 55.39%, but had only a mild effect on Star gene expression.

CONCLUSION(S)

Growth differential factor-9 can inhibit the production of testosterone in mouse theca interstitial cells and suppress the corresponding gene expression.

Chemerin suppresses ovarian follicular development and its potential involvement in follicular arrest in rats treated chronically with dihydrotestosterone

In the present study, we have investigated the cellular mechanisms of androgen-induced antral follicular growth arrest and the possible involvement of chemerin and its receptor chemokine-like receptor 1 (CMKLR1) in this process, using a chronically androgenized rat model. We hypothesize that hyperandrogenism induces antral follicle growth arrest via the action of chemerin and ovarian structural changes, resulting from granulosa cell and oocyte apoptosis and theca cell survival. Dihydrotestosterone (DHT) treatment resulted in increased expression of chemerin and CMKLR1 in antral follicles, absence of corpus luteum, and increased atypical follicles. Addition of chemerin to follicle cultures induced granulosa cell apoptosis and suppressed basal, FSH- and growth differentiation factor-9-stimulated follicular growth. DHT down-regulated aromatase expression and increased active caspase-3 content and DNA fragmentation in granulosa cells in vivo. These changes were accompanied by higher phosphatase and tensin homolog and lower phospho-Akt (Ser473) content in antral follicles and higher calpain expression and down-regulation of cytoskeletal proteins in atypical follicles, which were constituted predominantly of theca cells. DHT also activated granulosa cell caspase-3, decreased X-linked inhibitor of apoptosis protein, poly(ADP-ribose) polymerase, and phospho-Akt contents and induced apoptosis in vitro, responses readily attenuated by forced X-linked inhibitor of apoptosis protein expression. These findings are consistent with our hypothesis that antral follicular growth arrest in DHT-treated rats results from increased chemerin expression and action, as well as changes in follicular cell fate and structure, which are a consequence of dysregulated interactions of pro-survival and pro-apoptotic modulators in a cell-specific manner. Our observations suggest that this chronically androgenized rat model may be useful for studies on the long-term effects of androgens on folliculogenesis and may have implications for the female reproductive disorders associated with hyperandrogenism.

Replication study of RAD54B and GREB1 polymorphisms and risk of PCOS in Han Chinese

A previous genome-wide association study (GWAS) of polycystic ovary syndrome (PCOS) identified several susceptibility loci, with P-values about 10⁻⁵. In the present study, an independent cohort was used for a replication study to evaluate the association of RAD54B and GREB1 with polycystic ovary syndrome (PCOS) in the Han Chinese population. Four single-nucleotide polymorphisms (SNP), rs2930961 (RAD54B), rs12470971, rs11686574 and rs6740248 (GREB1), were genotyped in 1124 PCOS patients and 1067 healthy controls from the Han Chinese population. Real-time quantitative PCR by TaqMan-MGB probe assay was applied for genotyping. The allele and genotype frequencies of these four SNP were not significantly different in the replication cohort. However, the minor allele frequency of rs2930961 was significantly different in hyperandrogenism of PCOS. After meta-analysis by combining the results of these two studies, there was a non-significant trend for the association of rs2930961 (RAD54B) with PCOS. RAD54B and GREB1 gene polymorphisms may not be associated with PCOS in the Han Chinese population. Nevertheless, RAD54B may contribute to hyperandrogenism in PCOS patients.

Activation of latent human GDF9 by a single residue change (Gly 391 Arg) in the mature domain

Growth differentiation factor 9 (GDF9) controls granulosa cell growth and differentiation during early ovarian folliculogenesis and regulates cumulus cell function and ovulation rate in the later stages of this process. Similar to other TGF-β superfamily ligands, GDF9 is secreted from the oocyte in a noncovalent complex with its prodomain. In this study, we show that prodomain interactions differentially regulate the activity of GDF9 across species, such that murine (m) GDF9 is secreted in an active form, whereas human (h) GDF9 is latent. To understand this distinction, we used site-directed mutagenesis to introduce nonconserved mGDF9 residues into the pro- and mature domains of hGDF9. Activity-based screens of the resultant mutants indicated that a single mature domain residue (Gly(391)) confers latency to hGDF9. Gly(391) forms part of the type I receptor binding site on hGDF9, and this residue is present in all species except mouse, rat, hamster, galago, and possum, in which it is substituted with an arginine. In an adrenocortical cell luciferase assay, hGDF9 (Gly(391)Arg) had similar activity to mGDF9 (EC(50) 55 ng/ml vs. 28 ng/ml, respectively), whereas wild-type hGDF9 was inactive. hGDF9 (Gly(391)Arg) was also a potent stimulator of murine granulosa cell proliferation (EC(50) 52 ng/ml). An arginine at position 391 increases the affinity of GDF9 for its signaling receptors, enabling it to be secreted in an active form. This important species difference in the activation status of GDF9 may contribute to the variation observed in follicular development, ovulation rate, and fecundity between mammals.