Recombinant growth differentiation factor-9 (GDF-9) enhances growth and differentiation of cultured early ovarian follicles

Molecular forms of BMP15 and GDF9 in mammalian species that differ in litter size

Bone morphogenetic protein (BMP15) and growth differentiation factor (GDF9) are critical for ovarian follicular development and fertility and are associated with litter size in mammals. These proteins initially exist as pre-pro-mature proteins, that are subsequently cleaved into biologically active forms. Thus, the molecular forms of GDF9 and BMP15 may provide the key to understanding the differences in litter size determination in mammals. Herein, we compared GDF9 and BMP15 forms in mammals with high (pigs) and low to moderate (sheep) and low (red deer) ovulation-rate. In all species, oocyte lysates and secretions contained both promature and mature forms of BMP15 and GDF9. Whilst promature and mature GDF9 levels were similar between species, deer produced more BMP15 and exhibited, together with sheep, a higher promature:mature BMP15 ratio. N-linked glycosylation was prominant in proregion and mature GDF9 and in proregion BMP15 of pigs, and present in proregion GDF9 of sheep. There was no evidence of secreted native homo- or hetero-dimers although a GDF9 dimer in red deer oocyte lysate was detected. In summary, GDF9 appeared to be equally important in all species regardless of litter size, whilst BMP15 levels were highest in strict monovulatory species.

Combination treatment of recombinant growth differentiation factor-9 and Cetrorelix improves gestational origin of the polycystic ovarian syndrome in female rats

AIMS

Polycystic ovary syndrome (PCOS) is a hyper-androgenic endocrinopathy prevalent in premenopausal women with no cure available. The current study aimed to investigate the therapeutic effect of recombinant GDF-9 and Cetrorelix on the gestational origin of dehydroepiandrosterone (DHEA) induced PCOS in postnatal pups' delivered to rat dams.

MAIN METHODS

The body weight measurement, blood and serum analysis for glucose tolerance, lipid profile, liver enzymes, sex hormones (Testosterone, Estradiol, and Progesterone), estrus cyclicity assessment, histological staining of ovary and liver, molecular markers expressions of pro-inflammatory by qRT-PCR and immuno-histochemistry technique for folliculogenesis genes and histological staining studies of liver and ovary were done.

KEY FINDINGS

The combinational treatment was found to normalize the biochemical parameters and reduction in the estrus irregularity by altering the sex hormones as well as the glucose metabolism and insulin resistance via HOMA-IR value. Further, molecular markers expression confirmed the pro-inflammatory (IL-1β, TNF-α, and IL-6) and folliculogenesis (GDF-9, BMPR2, and TGF-βR1) genes associated with PCOS were improved by combinational therapy.

SIGNIFICANCE

In conclusion, rGDF-9 could be a potential therapeutic agent in combination with Cetrorelix as a better treatment regime for metabolic and reproductive phenotypes in PCOS. However, the effect of rGDF-9 on infertility-associated phenotypes in PCOS needs further evaluation.

Effects of IGF-1 on the Three-Dimensional Culture of Ovarian Preantral Follicles and Superovulation Rates in Mice

Insulin-like growth factor-1 (IGF-1) plays a crucial role during folliculogenesis, which has been demonstrated by previous research. However, the optimal IGF-1 dosage in the three-dimensional (3D) culture system is unknown. Mouse secondary follicles (140−150 µm) were cultured for 6 days within an alginate bead in a medium supplemented with 0 (G0), 5 ng/mL (G5), 10 ng/mL (G10), or 50 ng/mL IGF-1 (G50). Secretions of 17β-estradiol and progesterone were significantly increased in G10 and G50 (p < 0.05). However, G50 significantly inhibited follicular growth (p < 0.05), while G10 showed a higher oocyte maturation rate. Thus, the 10 ng/mL IGF-1 was used in subsequent experiments. IGF-1 enhanced the function of granulosa cells (GCs) by upregulating expressions of Star, Cyp19a1, Hsd3b1, Fshr, and Lhcgr. Oocyte secretory function was promoted by upregulating expressions of Bmp-15, Gdf-9, and Fgf-8. Addition of IGF-1 showed anti-apoptotic effect. However, G10 did not improve fertilization rate of MII oocytes compared to G0. In an intraperitoneal injection experiment in mice, IGF-1 significantly increased the number of ovulated oocytes (p < 0.05). In conclusion, 10 ng/mL IGF-1 can promote the production of mature oocytes in the 3D culture medium and injection of IGF-1 before superovulation increases the number of ovulated oocytes.

Mammalian cumulus-oocyte complex communication: a dialog through long and short distance messaging

Communications are crucial to ovarian follicle development and to ovulation, and while both folliculogenesis and oogenesis are distinct processes, they share highly interdependent signaling pathways. Signals from distant organs such as the brain must be processed and compartments within the follicle have to be synchronized. The hypothalamic–pituitary–gonadal (HPG) axis relies on long-distance signalling analogous to wireless communication by which data is disseminated in the environment and cells equipped with the appropriate receptors receive and interpret the messages. In contrast, direct cell-to-cell transfer of molecules is a very targeted, short distance messaging system. Numerous signalling pathways have been identified and proven to be essential for the production of a developmentally competent egg. The development of the cumulus-oocyte complex relies largely on short distance communications or direct transfer type via extensions of corona radiata cells through the zona pellucida. The type of information transmitted through these transzonal projections is still largely uncharacterized. This review provides an overview of current understanding of the mechanisms by which the gamete receives and transmits information within the follicle. Moreover, it highlights the fact that in addition to the well-known systemic long-distance based communications from the HPG axis, these mechanisms acting more locally should also be considered as important targets for controlling/optimizing oocyte quality.

Chicken ovarian follicles morphology and growth differentiation factor 9 gene expression in chicken ovarian follicles: review

Ovary follicular development is a progressive system from the beginning of small cortical follicles to the ovulation of hierarchical follicles. The review was conducted to provide information on the indigenous chickens commonly used for egg production, chicken ovarian follicles morphology and expression of growth differentiation factor 9 (GDF9) gene in ovarian follicles and its relationship with egg production. The research databases used in the study include google scholar, Science Direct, PubMed, JSTOR and Cambridge Core. Google, Yahoo and Baidu search engines were used to search the information. In this study, the papers selected for use were original research articles and reviews to ensure that the information used was from research results. Besides, only recent English papers, 2010-2021, were used. The keywords used to search for articles were chicken ovarian follicles, ovarian morphology and GDF9 gene expression. The documents showed that pre-hierarchical follicles include many small and large white follicles, which are about 2-5mm in diameter and 5 to 6 small yellow follicles (SYF) that are about 5-10mm in diameter. Preovulatory follicles are about five to six in number and above 10mm in diameter, with the sizes from F6 to F1, with F1 as the largest follicle. Further, the studies revealed that GDF9 gene mRNA is expressed in the highest concentration in small yellow follicles and other studies reported that the expression of GDF9 gene has been found in follicles of the primary to preovulatory stages in chickens. This review concludes that the GDF9 gene expression is mainly throughout follicular growth and it stimulates the proliferation of pre-hierarchical granulosa cells. The increased egg production in chickens depends on progressive developmental stages and the growth of ovarian follicles.

Association of FSHR, LH, LHR, BMP15, GDF9, AMH, and AMHR polymorphisms with poor ovarian response in patients undergoing in vitro fertilization

Objective:

This paper aimed to assess the correlation between LH, LHR, GDF9, FSHR, AMH, AMHR2, and BMP15 polymorphisms, which are related to follicular development, and decreased ovarian response in women undergoing controlled ovarian hyperstimulation (COH) for IVF.

Methods:

This age-matched case-control study included three or four controls per woman undergoing COH. Controls were women with normal ovarian response (NOR) and cases were women with poor ovarian response (POR) in oocyte retrieval (three or fewer oocytes). DNA was extracted from peripheral blood and potential associations with gene polymorphisms related to follicular development (LH, LHR, GDF9, FSHR, AMH, AMHR2, and BMP15) were analyzed.

Results:

Sixty-six patients were included, 52 in the NOR and 14 in the POR group. Two GDF9 polymorphisms were associated with follicular response after COH, one associated with POR - the presence of a mutant polymorphism in heterozygosis and homozygosis of the GDF9 398-39 (C to G) [23% NOR versus 68% POR (OR 4.01, CI 1.52-10.6, p=0.005)] - and another associated with protective response - the presence of normal homozygosis of GDF9 (C447T) [19.2% NOR versus 50% POR (OR 0.34, IC 0.14-0.84, p=0.019)]. No additional associations were found between the other analyzed polymorphisms and POR.

Conclusions:

This study found that GDF9 appears to play an important role in follicular development, whereas polymorphisms in its DNA chain may negatively affect ovarian reserve, such as 398-39 (C to G), or positively, as seen in C447T.

Effects of oocyte-derived growth factors on the growth of porcine oocytes and oocyte-cumulus cell complexes in vitro

During oocyte growth and follicle development, oocytes closely communicate with cumulus cells. We examined the effects of oocyte-derived growth factors, growth differentiation factor 9 (GDF9) and bone morphogenetic protein 15 (BMP15), on the growth and acquisition of meiotic competence of porcine oocytes collected from early antral follicles (1.2-1.5 mm). First, we confirmed that GDF9 and BMP15 mRNAs were expressed almost exclusively in the oocytes. Oocyte-cumulus cell complexes (OCCs) collected from early antral follicles were cultured in growth medium supplemented with 0-100 ng/ml of GDF9 or BMP15 for 5 days. GDF9 dose-dependently increased the OCC diameter, while BMP15 did not. GDF9 and BMP15 had no significant effects on oocyte growth (P > 0.05). When OCCs that had been cultured with 50 and 100 ng/ml BMP15 were subjected to a subsequent maturation culture, they expanded fully by gonadotropic stimulation and 49% and 61% of oocytes matured to metaphase II (MII), respectively. In contrast, GDF9 did not promote cumulus expansion, and < 10% of oocytes matured to MII. Based on the difference in cumulus expansion, we compared the expression of luteinizing hormone/choriogonadotropin receptor (LHCGR) and follicle stimulating hormone receptor (FSHR) mRNAs in cumulus cells. The level of LHCGR mRNA was increased in cumulus cells of the BMP15 group, although there were no significant differences in FSHR mRNA levels among the groups. These results suggest that GDF9 promotes the growth of OCCs and that BMP15 promotes LHCGR mRNA expression in cumulus cells during oocyte growth culture, which may contribute to cumulus expansion and oocyte maturation.

Human dermal fibroblasts support the development of human primordial/primary follicles in a 3-dimensional alginate matrix culture system

Background

Alginate matrix 3-dimensional culture offers the opportunity for the development and maturation of human secondary follicles in vitro. However, alginate may not be the most suitable culture system for human primordial/primary follicles in vitro. Thus, the innovation of alginate matrix 3-dimensional culture systems for human primordial/primary follicles could hold promise as an ideal approach to restoring fertility.

Methods

We extracted primordial/primary follicles from ovarian tissues collected from patients with non-ovarian benign gynecological conditions. Fibroblasts were isolated from dermal tissue from 1 male patient who had undergone posthectomy. The isolated human follicles were randomly divided into 2 groups and encapsulated within fibroblast-alginate-hydrogels or alginate hydrogels. The survival and growth of human primordial/primary follicles were measured after 21 days of in vitro culture.

Results

The dermal fibroblasts in alginate hydrogel microcapsules were round in shape, and were distributed as uniform clouds on the surface and gaps of the alginate. After 21 days of culture, the survival rate of follicles in the fibroblast-alginate group was higher than that of the alginate group (P<0.05). The diameter of follicles in the fibroblast-alginate group and the alginate group after 21 days of culture was 152.80±13.64 and 129.14±9.95 μm, respectively (P<0.05). After 21-day culture, the mean cpm (log-converted) for 3H-thymidine incorporated by granulosa cells in the fibroblast-alginate and alginate groups was 6.87±0.24 and 4.63±0.38, respectively (P<0.05). After 21 days of culture, the messenger RNA expression levels of growth differentiation factor 9 (GDF9) and bone morphogenetic protein 15 (BMP15) were significantly higher in oocytes in fibroblast-alginate hydrogels than in those in alginate hydrogels (P<0.05).

Conclusions

Human fibroblasts are beneficial to the development of human follicles in 3-dimensional culture alginate gel systems over a long period of time. More studies are required to investigate the molecular biological mechanisms of human fibroblasts that promote follicle growth in vitro.

Separation of Oocyte and Follicle Layer for Gene Expression Analysis in Zebrafish

Zebrafish ovarian follicles are mainly composed of the oocyte and a thin layer of follicle cells. Recent studies have demonstrated extensive cell-cell interactions between the oocyte and surrounding follicle layer and that the two compartments communicate mostly through paracrine factors. To understand the paracrine communication within the follicle, it is essential to know the spatial expression patterns of genes in the two compartments. However, since the follicle layer is extremely thin and the oocytes are enormous in size in fish, it is often difficult to detect gene expression by traditional methods such as in situ hybridization. Separation of the oocyte and surrounding follicle layer followed by RT-PCR detection provides a sensitive way to reveal the expression of individual genes in the two compartments of the follicle. This chapter introduces a method for mechanic separation of the oocyte and follicle layer at full-grown stage for expression analysis. Since fish have similar follicle structure, this method may also be used in other species as well.

Effects of Growth and Differentiation Factor 9 and Bone Morphogenetic Protein 15 overexpression on the steroidogenic metabolism in bovine granulosa cells in vitro

Granulosa cells (GCs) play important roles in the regulation of ovarian functions, and in vitro culture is a relevant model for the study of steroidogenesis in ovarian follicles. Thus, growth factors secreted by the oocyte, like Growth and Differentiation Factor 9 (GDF9) and Bone Morphogenetic Protein 15 (BMP15), play an important part in the luteinization of granulosa cells. The aim of this work was to express GDF9 and BMP15 genes in bovine GCs in vitro and evaluate their effects on the luteinization process. Samples of culture medium and GCs transfected with GDF9 and BMP15 were obtained for 21 consecutive days to analyse the steroidogenic hormones' concentration (progesterone (P₄ ) and estradiol (E₂ )) and the expression of STAR, GDF9 and BMP15 and their respective receptors. The results demonstrated an inhibitory effect of GDF9 and BMPF15 on P₄ secretion in bovine GCs cultured in vitro. Moreover, our study demonstrated the entire expression of their respective receptors (TGFBR1, BMPR1B and BMPR2) and the inhibition of the steroidogenic marker, STAR gene. This work sheds light on a novel biological function of BMP15 and GDF9 in bovine GCs physiology, which could elucidate a non-described biological role for GDF9 and BMP15 in bovine granulosa cells' metabolism.

Effect of growth differentiation factor 9 (GDF-9) on in vitro development of collared peccary preantral follicles in ovarian tissues

The aims were to identify the effects of growth differentiation factor 9 (GDF-9) on the in vitro development of ovarian preantral follicles (PAFs) of collared peccaries. Ovarian fragments were in vitro cultured for 1 or 7 days without or with inclusion of GDF-9 in the medium (0, 50, 100, or 200 ng/mL). The non-cultured (control) and cultured fragments were evaluated for PAF viability, activation, and cell proliferation. Although there were no differences in the percentage of morphologically normal follicles, the percentage of growing follicles was greater compared to the control in all treatment groups, especially those cultured with 200 ng/mL GDF-9 for 7 days (P < 0.05). The inclusion of GDF-9 in the medium did not interfere with PAF viability (P> 0.05); however, treatment with 200 ng/mL GDF-9 resulted in greater (P < 0.05) cell proliferation in PAFs cultured for 1 or 7 days (∼2.5 nucleolar organizing regions - NORs) compared to the follicles of the control group (2.0 NORs). In addition, peccary ovarian cortexes were subjected to PCR analysis and there was detection of the mRNA GDF-9 receptor transcripts of the BMPR2 (type I receptor) and ALK-5 (type II receptor) types. In conclusion, GDF-9, especially at a 200 ng/mL inclusion in the culture medium, was actively involved in the in vitro development of collared peccary PAFs.

Detrimental effect of Bisphenol S in mouse germ cell cyst breakdown and primordial follicle assembly

The female reproductive lifespan is largely determined by the size of primordial follicle pool, which is established in early life. Bisphenol S (BPS), frequently present in plastic products used in daily life, has been demonstrated as an exogenous estrogen-like endocrine disrupting chemical interfering with the endocrine and reproductive systems. However, the molecular mechanisms of its reproductive toxicity remain to be determined. In the present study, we focused on the effect of BPS on the early ovarian folliculogenesis of mice. Our in vivo experiments showed that the treatment with BPS at 2 and 10 μg/kg body weight/day for 3 days induced abnormal germ cell cyst breakdown and primordial follicle assembly in the mouse ovary, further affecting later ovarian differentiation and reducing oocyte quality. In addition, our in vitro study demonstrated that BPS could interact with estrogen receptors (ERs) to induce phosphorylation of JNKs, which is responsible for reducing oocyte adhesion in cysts. Meanwhile, BPS exposure up-regulated Notch signaling pathway to increase the proliferation of granulosa cells precursors. Our study provided new evidence for the adverse effects of BPS on female reproduction, especially after perinatal exposure, and elucidated how it works.

Signalling pathways and mechanistic cues highlighted by transcriptomic analysis of primordial, primary, and secondary ovarian follicles in domestic cat

In vitro growth (IVG) of dormant primordial ovarian follicles aims to produce mature competent oocytes for assisted reproduction. Success is dependent on optimal in vitro conditions complemented with an understanding of oocyte and ovarian follicle development in vivo. Complete IVG has not been achieved in any other mammalian species besides mice. Furthermore, ovarian folliculogenesis remains sparsely understood overall. Here, gene expression patterns were characterised by RNA-sequencing in primordial (PrF), primary (PF), and secondary (SF) ovarian follicles from Felis catus (domestic cat) ovaries. Two major transitions were investigated: PrF-PF and PF-SF. Transcriptional analysis revealed a higher proportion in gene expression changes during the PrF-PF transition. Key influencing factors during this transition included the interaction between the extracellular matrix (ECM) and matrix metalloproteinase (MMPs) along with nuclear components such as, histone HIST1H1T (H1.6). Conserved signalling factors and expression patterns previously described during mammalian ovarian folliculogenesis were observed. Species-specific features during domestic cat ovarian folliculogenesis were also found. The signalling pathway terms "PI3K-Akt", "transforming growth factor-β receptor", "ErbB", and "HIF-1" from the functional annotation analysis were studied. Some results highlighted mechanistic cues potentially involved in PrF development in the domestic cat. Overall, this study provides an insight into regulatory factors and pathways during preantral ovarian folliculogenesis in domestic cat.

GDF9 polymorphisms: influence on ovarian response in women undergoing controlled ovarian hyperstimulation

OBJECTIVE

The study looked into the possible influence of GDF9 polymorphisms on ovarian response in women with a normal ovarian reserve undergoing controlled ovarian hyperstimulation for in vitro fertilization (IVF).

METHODS

This cross-sectional study included 67 women with normal ovarian reserve aged 30-39 years submitted to controlled ovarian hyperstimulation for IVF. We sequenced four polymorphisms in the GDF9 gene (C398G, C447T, G546A, and G646A) and analyzed their influence on follicular and oocyte outcomes.

RESULTS

The mutant allele C398G decreased the total number of follicles >17mm (6.49 vs. 4.33, p=0.001), total number of follicles (10.11 vs. 7.33, p=0.032), number of MII oocytes retrieved, and serum progesterone levels on trigger day. The C447T polymorphism was associated with a greater number of follicles between 12 and 14 mm on the day of r-hCG, while the G546A polymorphism was associated with lower serum progesterone levels on trigger day.

CONCLUSIONS

GDF9 gene polymorphisms C398G and C447T adversely affected ovarian response in women undergoing controlled ovarian hyperstimulation. These findings show that in addition to playing a role in the early stages of folliculogenesis, GDF9 polymorphisms have an important impact on the final stage of oocyte development.

Melatonin on hypothyroidism and gonadal development in rats: a review

We evaluated the evidence in research on the effects of melatonin on hypothyroidism and gonadal development. According to the World Health Organization, thyroid disorders due to iodine deficiency affect about 740 million people worldwide. Hypothyroidism is a thyroid dysfunction characterized by hypometabolism of the gland, with reduced or physiologically normal T3 and T4 serum levels, and high TSH level. This disorder occurs mainly in adult women in the reproductive phase, with a prevalence of 2% among the world's female population, with profound repercussions on gestation and fetal formation. During the gestational period, the thyroid is initially stimulated by high concentrations of human chorionic gonadotrophin; thus, maintaining maternal euthyroidism during pregnancy and lactation is fundamental for fetal growth and development. Besides, the hormones produced by this gland are involved in the formation of various organs, such as the skin, brain and gonads. Hypothyroidism is associated with several menstrual abnormalities, anovulation and hyperprolactinemia, resulting in a high rate of abortions, premature births, placental rupture, and weight-related neonatal deficits. In addition, there are studies showing that hypothyroidism can affect ovarian morphology (number of ovarian follicles) and testicular morphology (changes in the testicular-lumen epithelium). Melatonin is a hormone known to modulate the estrous cycle and pregnancy, and studies show that the exogenous application of melatonin increased T4 levels in female rats and controlled the decrease in T3 serum levels, reverting the sigs of hypothyroidism.

Localization of angiotensin-(1-7) and Mas receptor in the rat ovary throughout the estrous cycle

We have previously demonstrated the presence of Angiotensin (Ang)-(1-7) in rat ovary homogenates and its stimulatory effect on estradiol and progesterone production. The present study was undertaken to identify the cellular localization of Ang-(1-7) and its receptor Mas in the rat ovary in the different phases of the estrous cycle. Ang-(1-7) and Mas were localized by immunohistochemistry and Mas mRNA expression was assessed by RT-PCR. Immunostaining for both Ang-(1-7) and Mas was found in all phases of the estrous cycle, particularly in the thecal and interstitial cells, as well as in regressing corpora lutea. However, granulosa cells were positive only in antral and preovulatory follicles at proestrus and estrus phases. This pattern contrasted with the distribution of the octapeptide Ang II, which was abundant in granulosa but not in theca cells. In addition, the expression of Mas mRNA was demonstrated in all estrous cycle phases. Angiotensin-converting enzyme activity did not vary between estrous cycle phases, whereas prolyl endopeptidase activity was significantly higher in diestrus and neutral endopeptidase activity was significantly higher in metestrus. These data provide the first evidence that new RAS components are dynamically expressed in the ovary across the rat estrous cycle. Further functional studies should clarify the role of Ang-(1-7) signaling through Mas receptor in the regulation of ovarian physiology.

Human embryonic stem cell-derived mesenchymal stem cells improved premature ovarian failure

BACKGROUND

Premature ovarian failure (POF) affects many adult women less than 40 years of age and leads to infertility. According to previous reports, various tissue-specific stem cells can restore ovarian function and folliculogenesis in mice with chemotherapy-induced POF. Human embryonic stem cells (ES) provide an alternative source for mesenchymal stem cells (MSCs) because of their similarities in phenotype and immunomodulatory and anti-inflammatory characteristics. Embryonic stem cell-derived mesenchymal stem cells (ES-MSCs) are attractive candidates for regenerative medicine because of their high proliferation and lack of barriers for harvesting tissue-specific MSCs. However, possible therapeutic effects and underlying mechanisms of transplanted ES-MSCs on cyclophosphamide and busulfan-induced mouse ovarian damage have not been evaluated.

AIM

To evaluate ES-MSCs vs bone marrow-derived mesenchymal stem cells (BM-MSCs) in restoring ovarian function in a mouse model of chemotherapy-induced premature ovarian failure.

METHODS

Female mice received intraperitoneal injections of different doses of cyclophosphamide and busulfan to induce POF. Either human ES-MSCs or BM-MSCs were transplanted into these mice. Ten days after the mice were injected with cyclophosphamide and busulfan and 4 wk after transplantation of the ES-MSCs and/or BM-MSCs, we evaluated body weight, estrous cyclicity, follicle-stimulating hormone and estradiol hormone concentrations and follicle count were used to evaluate the POF model and cell transplantation. Moreover, terminal deoxynucleotidyl transferase mediated 2-deoxyuridine 5-triphosphate nick end labeling, real-time PCR, Western blot analysis and immunohistochemistry and mating was used to evaluate cell transplantation. Enzyme-linked immunosorbent assay was used to analyze vascular endothelial growth factor, insulin-like growth factor 2 and hepatocyte growth factor levels in ES-MSC condition medium in order to investigate the mechanisms that underlie their function.

RESULTS

The human ES-MSCs significantly restored hormone secretion, survival rate and reproductive function in POF mice, which was similar to the results obtained with BM-MSCs. Gene expression analysis and the terminal deoxynucleotidyl transferase mediated 2-deoxyuridine 5-triphosphate nick end labeling assay results indicated that the ES-MSCs and/or BM-MSCs reduced apoptosis in the follicles. Notably, the transplanted mice generated new offspring. The results of different analyses showed increases in antiapoptotic and trophic proteins and genes.

CONCLUSION

These results suggested that transplantation of human ES-MSCs were similar to BM-MSCs in that they could restore the structure of the injured ovarian tissue and its function in chemotherapy-induced damaged POF mice and rescue fertility. The possible mechanisms of human ES-MSC were related to promotion of follicular development, ovarian secretion, fertility via a paracrine effect and ovarian cell survival.

Growth Factors, and Cytokines; Understanding the Role of Tyrosine Phosphatase SHP2 in Gametogenesis and Early Embryo Development

Growth factors and cytokines have vital roles in germ cell development, gamete maturation, and early embryo development. Cell surface receptors are present for growth factors and cytokines to integrate with and trigger protein signaling in the germ and embryo intracellular milieu. Src-homology-2-containing phosphotyrosine phosphatase (SHP2) is a ubiquitously expressed, multifunctional protein that plays a central role in the signaling pathways involved in growth factor receptors, cytokine receptors, integrins, and G protein-coupled receptors. Over recent decades, researchers have recapitulated the protein signaling networks that influence gamete progenitor specification as well as gamete differentiation and maturation. SHP2 plays an indispensable role in cellular growth, survival, proliferation, differentiation, and migration, as well as the basic events in gametogenesis and early embryo development. SHP2, a classic cytosolic protein and a key regulator of signal transduction, displays unconventional nuclear expression in the genital organs. Several observations provided shreds of evidence that this behavior is essential for fertility. The growth factor and cytokine-dependent roles of SHP2 and its nuclear/cytoplasmic presence during gamete maturation, early embryonic development and embryo implantation are fascinating and complex subjects. This review is intended to summarize the previous and recent knowledge about the SHP2 functions in gametogenesis and early embryo development.

Intrafollicular growth differentiation factor 9: bone morphogenetic 15 ratio determines litter size in mammals†

We previously showed that rat, pig, sheep, and red deer oocytes express species-specific ratios of GDF9: BMP15 mRNA (3.7, 0.5, 1.26, and 0.1, respectively), and with the exception of the pig, they are directly correlated to litter size. The purpose of this study was to determine the alternative mechanism that enables pig oocytes to secrete low ratios whilst maintaining a large litter size. Herein, we performed same- and cross-species coincubations of oocytes with granulosa cells (GCs) of rat, pig, sheep, and red deer to compare the proliferation rate, mRNA expression levels of growth factor receptors, and downstream signalling pathways in GCs. A decreased proliferation rate, lower Bmpr1b and Bmpr2 mRNA expression levels, and higher SMAD1/5/8 protein levels were exhibited in rat GCs cocultured with red deer oocytes, compared to all other species. Pig GCs unequivocally expressed GDF9 mRNA, suggesting that, similar to rat GCs, the proliferation of pig GCs is regulated mainly by GDF9, despite lower intraoocyte expression of GDF9 mRNA. In support, a higher basal proliferation, and their ability to proliferate readily when coincubated with red deer oocytes, was observed in pig GCs. In contrast, red deer GC proliferation is likely to be mainly regulated by BMP15 in vivo with only red deer oocytes capable of altering SMAD1/5/8 and pSMAD2/3 levels, while both GDF9 and BMP15 appear important for sheep GC proliferation. In summary, this study strengthens our hypothesis that the ratio of GDF9: BMP15 in the intrafollicular milieu is directly correlated with litter size, and that the GCs of each species have evolved to respond to these unique ratios.

Expression patterns and oestradiol regulation of growth differentiation factor 9 in Schizothorax prenanti

Growth differentiation factor 9 (GDF9) plays pivotal roles in regulating follicular development in many mammalian species. In the present study, the full-length Schizothorax prenanti gdf9 cDNA sequence was isolated and characterized, and its expression pattern in developing gonads and in the gonads of exogenous oestradiol (E₂)-fed fish were analysed. The S. prenanti gdf9 cDNA sequence consisted of 1958 base pairs (bp), encoded a 413 amino acid, and showed high sequence similarity with Carassius gibelio and Cyprinus carpio. The quantitative real-time PCR analysis revealed that gdf9 was mainly expressed in the gonads, with particularly high expression in the cortical alveoli stage ovary and late-spermatogenic stage testis. Immunohistochemical signals for Gdf9 were mainly detected in chromatin nucleolar oocytes, spermatogonia and spermatocytes. Furthermore, the gonadal expression of gdf9 induced by exogenous E₂ was related to the feeding time and dose. Taken together, these findings were helpful to gain a better understanding of the role of Gdf9 in both folliculogenesis and spermatogenesis in S. prenanti.

DPAGT1-Mediated Protein N-Glycosylation Is Indispensable for Oocyte and Follicle Development in Mice

Post-translational modification of proteins by N-linked glycosylation is crucial for many life processes. However, the exact contribution of N-glycosylation to mammalian female reproduction remains largely undefined. Here, DPAGT1, the enzyme that catalyzes the first step of protein N-glycosylation, is identified to be indispensable for oocyte development in mice. Dpagt1 missense mutation (c. 497A>G; p. Asp166Gly) causes female subfertility without grossly affecting other functions. Mutant females ovulate fewer eggs owing to defective development of growing follicles. Mutant oocytes have a thin and fragile zona pellucida (ZP) due to the reduction in glycosylation of ZP proteins, and display poor developmental competence after fertilization in vitro. Moreover, completion of the first meiosis is accelerated in mutant oocytes, which is coincident with the elevation of aneuploidy. Mechanistically, transcriptomic analysis reveals the downregulation of a number of transcripts essential for oocyte meiotic progression and preimplantation development (e.g., Pttgt1, Esco2, Orc6, and Npm2) in mutant oocytes, which could account for the defects observed. Furthermore, conditional knockout of Dpagt1 in oocytes recapitulates the phenotypes observed in Dpagt1 mutant females, and causes complete infertility. Taken together, these data indicate that protein N-glycosylation in oocytes is essential for female fertility in mammals by specific control of oocyte development.

Incorporation of arginine, glutamine or leucine in culture medium accelerates in vitro activation of primordial follicles in 1-day-old mouse ovary

In vitro activation of primordial follicles provides cancer patients subjected to oncotherapy with a safe therapeutic strategy for fertility preservation, however a successful protocol for activation of primordial follicles in prepubertal patients has not yet been defined comprehensively. There is evidence that amino acids such as leucine, arginine and glutamine could stimulate the mammalian target of rapamycin (mTOR) pathway, which plays a pivotal role in primordial follicle activation. Nevertheless, there has been no report that elucidates the effect of these amino acids on in vitro development of ovarian follicles. Therefore, the present study was conducted to evaluate the effects of these amino acids and their combination on the formation and activation of primordial follicles in 1-day-old murine ovaries during an 11-day culture period. The experimental groups consisted of base medium (BM), base medium + arginine (ARG), base medium + glutamine (GLU), base medium + leucine (LEU) and base medium + a combination of arginine, glutamine and leucine (AGL). The proportions of different stages of ovarian follicles and gene expression of regulatory factors were assessed using histology and quantitative real-time PCR on days 5 and 11 of culture. The proportion of transitional and primary follicles was greater in all amino acid-treated groups compared with the BM group (P < 0.05). Moreover, leucine resulted in elevated expression of Gdf9 and Bmp15, and glutamine augmented the expression of Pi3k on day 11 of culture. In conclusion, the present study showed that inclusion of leucine, glutamine, arginine or their combination in the culture medium for murine ovarian tissue could accelerate the activation of primordial follicles and alter the expression of the corresponding factors.

C-type natriuretic peptide enhances mouse preantral follicle growth

Compared to ovarian antral follicle development, the mechanism underlying preantral follicle growth has not been well documented. Although C-type natriuretic peptide (CNP) involvement in preantral folliculogenesis has been explored, its detailed role has not been fully defined. Here, we used mouse preantral follicles and granulosa cells (GCs) as a model for investigating the dynamic expression of CNP and natriuretic peptide receptor 2 (NPR2) during preantral folliculogenesis, the regulatory role of oocyte-derived growth factors (ODGFs) in natriuretic peptide type C (Nppc) and Npr2 expression, and the effect of CNP on preantral GC viability. Both mRNA and protein levels of Nppc and Npr2 were gradually activated during preantral folliculogenesis. CNP supplementation in culture medium significantly promoted the growth of in vitro-cultured preantral follicles and enhanced the viability of cultured GCs in a follicle-stimulating hormone (FSH)-independent manner. Using adult and prepubertal mice as an in vivo model, CNP pre-treatment via intraperitoneal injection before conventional superovulation also had a beneficial effect on promoting the ovulation rate. Furthermore, ODGFs enhanced Nppc and Npr2 expression in the in vitro-cultured preantral follicles and GCs. Mechanistic study demonstrated that the regulation of WNT signaling and estrogen synthesis may be implicated in the promoting role of CNP in preantral folliculogenesis. This study not only proves that CNP is a critical regulator of preantral follicle growth, but also provides new insight in understanding the crosstalk between oocytes and somatic cells during early folliculogenesis.

A Comparative Analysis of Oocyte Development in Mammals

Sexual reproduction requires the fertilization of a female gamete after it has undergone optimal development. Various aspects of oocyte development and many molecular actors in this process are shared among mammals, but phylogeny and experimental data reveal species specificities. In this chapter, we will present these common and distinctive features with a focus on three points: the shaping of the oocyte transcriptome from evolutionarily conserved and rapidly evolving genes, the control of folliculogenesis and ovulation rate by oocyte-secreted Growth and Differentiation Factor 9 and Bone Morphogenetic Protein 15, and the importance of lipid metabolism.

Luteinizing Hormone Action in Human Oocyte Maturation and Quality: Signaling Pathways, Regulation, and Clinical Impact

The ovarian follicle luteinizing hormone (LH) signaling molecules that regulate oocyte meiotic maturation have recently been identified. The LH signal reduces preovulatory follicle cyclic nucleotide levels which releases oocytes from the first meiotic arrest. In the ovarian follicle, the LH signal reduces cyclic nucleotide levels via the CNP/NPR2 system, the EGF/EGF receptor network, and follicle/oocyte gap junctions. In the oocyte, reduced cyclic nucleotide levels activate the maturation promoting factor (MPF). The activated MPF induces chromosome segregation and completion of the first and second meiotic divisions. The purpose of this paper is to present an overview of the current understanding of human LH signaling regulation of oocyte meiotic maturation by identifying and integrating the human studies on this topic. We found 89 human studies in the literature that identified 24 LH follicle/oocyte signaling proteins. These studies show that human oocyte meiotic maturation is regulated by the same proteins that regulate animal oocyte meiotic maturation. We also found that these LH signaling pathway molecules regulate human oocyte quality and subsequent embryo quality. Remarkably, in vitro maturation (IVM) prematuration culture (PMC) protocols that manipulate the LH signaling pathway improve human oocyte quality of cultured human oocytes. This knowledge has improved clinical human IVM efficiency which may become a routine alternative ART for some infertile patients.

Novel PMM2 missense mutation in a Chinese family with non-syndromic premature ovarian insufficiency

PURPOSE

This study sought to identify a disease-related gene in a consanguineous Chinese family in which there were two premature ovarian insufficiency (POI) sisters.

METHOD

We used whole-exome sequencing and Sanger sequencing to identify the disease-causing gene. Results were verified using an assay of mutant protein and in silico analyses.

RESULT

We identified a novel missense mutation (NM_000303: c.556G>A, p.Gly186Arg) in the PMM2 gene. The two sisters suffer from premature ovarian insufficiency (POI) only and have no other symptoms of congenital disorder of glycosylation type-1a (CDG-Ia). We found that the enzymic activity of the mutant PMM2 protein was reduced by 55.21% (p < 0.05) when compared with wild type, and many in silico tools suggested the mutation is disease-related.

CONCLUSION

This particular gene modification results in changes in activity of phosphomannomutase modification, which could lead to PMM2-CDG-Ia with an uncommon phenotype.

Interaction between growing oocytes and granulosa cells in vitro

BACKGROUND

Oocyte growth is accompanied by follicular development in mammalian ovaries. Since the discovery of two oocyte-derived factors, growth differentiation factor 9 (GDF9), and bone morphogenetic protein 15 (BMP15), knowledge of the bidirectional communication between oocytes and granulosa cells for ovarian function and fertility has been accumulated. In addition, the growth culture system of oocytes has been improved, further promoting the studies on the communication between oocytes and granulosa cells in vitro.

METHODS

We provide an overview of the role of granulosa cells in oocyte growth and the role of oocytes in follicular development along with our recent findings in culture experiments of bovine growing oocytes.

MAIN FINDINGS

Granulosa cells supply nutrients and metabolites through gap junctions to oocytes and secrete paracrine signals to regulate oocytes. Oocytes regulate granulosa cell proliferation and differentiation and induce antrum formation via GDF9 and BMP15.

CONCLUSION

Oocytes actively participate in various aspects of follicular development, including antrum formation via the oocyte-derived factors GDF9 and BMP15, whose synthesis is probably regulated by granulosa cells. In vitro studies will reveal the precise communication loop between oocytes and granulosa cells that facilitates the coordinated development of oocytes and granulosa cells in the follicles.

Vitrification has detrimental effects on maturation, viability, and subcellular quality of oocytes post IVM in cancerous women: An experimental study

Background

In vitro maturation (IVM) of immature oocytes retrieved from ovarian tissue has been considered as a valuable approach for fertility preservation in cancerous patients.

Objective

To evaluate the efficacy of vitrification on oocyte maturation, survival rates, as well as the subcellular oocyte quality post IVM.

Materials and Methods

The ovarian cortexes from 19 women with cervix and uterine malignancy aged 21-39 yr were collected. Cumulus-oocyte complexes were aspirated from all visible antral follicles. 102 immature oocytes were collected, and 43 oocytes were detected appropriately for IVM (control group). Also, 59 immature oocytes were vitrified, then matured in vitro (IVM) in two groups: with Growth/differentiation factor 9 (GDF9) (group 1) and without GDF9 (group 2) supplementation. Rates of oocytes viability, maturation, and survival along with meiotic spindle visualization and zona pellucida birefringence were assessed with Polyscope.

Results

The rate of maturation was significantly higher in controls (55.8%) compared to the other groups. Maturation rate was 23.3% in oocytes cultured in IVM medium enriched with GDF9, and 27.6% in those cultured in IVM medium lacking GDF9 (p = 0.86). Also, the meiotic spindle was present in 74.4% of control oocytes which was significantly higher than the other groups. The proportion of high zona pellucida birefringence was higher in the controls when compared with group 1 (51.2% vs. 23.3%, respectively, p = 0.04).

Conclusion

Vitrification had a detrimental effect on oocyte maturation, viability as well as the subcellular quality of the oocytes after IVM in cancerous women.

The role of FSH and TGF-β superfamily in follicle atresia

Most of the mammalian follicles undergo a degenerative process called “follicle atresia”. Apoptosis of granulosa cells is the main characteristic of follicle atresia. Follicle stimulating hormone (FSH) and the transforming growth factor β (TGF-β) superfamily have important regulatory functions in this process. FSH activates protein kinase A and cooperating with insulin receptor substrates, it promotes the PI3K/Akt pathway which weakens apoptosis. Both Smad or non-Smad signaling of the transforming growth factor β superfamily seem to be related to follicle atresia, and the effect of several important family members on follicle atresia is concluded in this article. FSH and TGF-β are likely to mutually influence each other and what we have already known about the possible underlying molecular mechanism is also discussed below.

Oocyte-Secreted Factors Synergize With FSH to Promote Aromatase Expression in Primary Human Cumulus Cells

CONTEXT

The role of growth differentiation factor 9 (GDF9) and bone morphogenetic protein 15 (BMP15) on aromatase regulation is poorly understood in humans.

OBJECTIVE

Determine GDF9 and BMP15 effects on FSH stimulation of estradiol production in primary human cumulus granulosa cells (GCs). We hypothesized that the combination of GDF9 and BMP15 potentiates FSH-induced aromatase expression.

DESIGN

Primary human cumulus GCs in culture.

SETTING

University infertility center.

PATIENTS OR OTHER PARTICIPANTS

GCs of 60 women undergoing in vitro fertilization were collected.

INTERVENTIONS

Cells were treated with GDF9 and/or BMP15 (GB) in the presence or absence of FSH, dibutyryl cAMP, or SMAD inhibitors.

MAIN OUTCOME MEASURES

Promoter activity, mRNA, protein, and estradiol levels were quantified.

RESULTS

FSH and GB treatment increased CYP19A1 promoter activity, mRNA, and protein levels as well as estradiol when compared with cells treated with FSH only. GB treatment potentiated cAMP stimulation of aromatase and IGF2 stimulation by FSH. GB effects were inhibited by SMAD3 inhibitors and IGF1 receptor inhibitors. GB, but not FSH, stimulates SMAD3 phosphorylation.

CONCLUSION

The combination of GDF9 and BMP15 potently stimulates the effect of FSH and cAMP on CYP19a1 promoter activity and mRNA/protein levels. These effects translate into an increase in estradiol production. This potentiation seems to occur through activation of the SMAD2/3 and SMAD3 signaling pathway and involves, at least in part, the effect of the IGF system.

SMAD3 directly regulates cell cycle genes to maintain arrest in granulosa cells of mouse primordial follicles

Primordial follicles, consisting of granulosa cell (GC)-enveloped oocytes are maintained in a state of developmental arrest until activated to grow. The mechanism that operates to maintain this arrested state in GCs is currently unknown. Here, we show the TGFβ-activated transcription factor SMAD3 is expressed in primordial GC nuclei alongside the cell cycle proteins, cyclin D2 (CCND2) and P27. Using neonatal C57/Bl6 mouse ovaries densely populated with primordial follicles, CCND2 protein co-localised and was detected in complex with P27 by immunofluorescence and co-immunoprecipitation, respectively. In the same tissue, SMAD3 co-precipitated with DNA sequences upstream of Ccnd2 and Myc transcription start sites implicating both as direct SMAD3 targets. In older ovaries follicle growth was associated with nuclear exclusion of SMAD3 and reduced P27 and CCND2 in GCs, alongside elevated Myc expression. Brief (2 H) exposure of neonatal ovaries to TGFβ1 (10 ng/ml) in vitro led to immediate dissociation of SMAD3 from the Ccnd2 and Myc promoters. This coincided with elevated Myc and phospho-S6, an indicator of mTOR signalling, followed by a small increase in mean primordial GC number after 48 H. These findings highlight a concentration-dependent role for TGFβ signalling in the maintenance and activation of primordial follicles, through SMAD-dependent and independent signalling pathways, respectively.

Follicle development as an orchestrated signaling network in a 3D organoid

The ovarian follicle is the structural and functional unit of the ovary, composed of the female gamete (the oocyte) and supportive somatic cells. Follicles are not only the source of a female's germ cell supply, but also secrete important hormones necessary for proper endocrine function. Folliculogenesis, the growth and maturation of the follicular unit, is a complex process governed by both intrafollicular crosstalk and pituitary-secreted hormones. While the later stages of this process are gonadotropin-dependent, early folliculogenesis appears to be controlled by the ovarian microenvironment and intrafollicular paracrine and autocrine signaling. In vitro follicle culture remains challenging because of the limited knowledge of growth factors and other cytokines influencing early follicle growth. Here we discuss the current state of knowledge on paracrine and autocrine signaling influencing primary follicles as they develop into the antral stage. Given the importance of intrafollicular signaling and the ovarian microenvironment, we reviewed the current engineering approaches for in vitro follicle culture, including 3D systems using natural hydrogels such as alginate and synthetic hydrogels such as poly(ethylene glycol). Our discussion is focused on what drives the proliferation of granulosa cells, development of the thecal layer, and antrum formation-three processes integral to follicle growth up to the antral stage. Further research in this area may reveal the mechanisms behind these complex signaling relationships within the follicle, leading to more successful and physiologically-relevant in vitro culture methods that will translate well to clinical applications.

Influence of growth differentiation factor 9 and bone morphogenetic protein 15 on in vitro maturation of canine oocytes

Growth differentiation factor 9 (GDF-9) and bone morphogenetic protein 15 (BMP-15) have pivotal roles in oocyte development in many species, therefore the aim was to investigate these factors during in vitro maturation (IVM) of canine oocytes. Canine cumulus oocytes complexes (COCs) were cultured in six groups for 72 hr in a supplemented TCM199-Hepes medium as (a) Control group; (b) GDF-9 antibody (Ab); (c) BMP-15 Ab; (d) recombinant human (rh) GDF-9; (e) rh BMP-15 or (f) rh BMP-15 and GDF-9. Data were evaluated by ANOVA. The Abs against GDF-9 or BMP-15 had a negative impact on meiotic development. Higher (p < 0.05) number of oocytes was arrested at GVBD stage when they were incubated with either GDF-9 Ab (64.4 ± 2.1%) or BMP-15 Ab (67.2%± 4.9%) in comparison to those in control group (32.4 ± 7.8%). In contrast, more (p < 0.05) oocytes in control group reached MI (37.4 ± 1.3%) and MII stages (10.2 ± 2.1%) comparing to those groups with GDF-9 Ab (23.1 ± 4.7% MI; 0.0% MII) or BMP-15 Ab (16.4 ± 2.4%MI; 5.9% ± 2.1 MII). Higher rates (p < 0.05) of oocytes in control group stayed still arrested at GV (19.9 ± 8.6%) in comparison to those cultured with either rhGDF-9 (3.7 ± 0.4%) or rhBMP-15 (10.9 ± 0.7%). However, there were no differences in MII rates between oocytes cultured with GDF-9 (14.7 ± 3.1) and BMP-15 (7.8 ± 2.5) separately. But, more oocytes (p < 0.05) reached the MII stage (20.5 ± 3.8%) compared to those exposed to each protein separately and to the control group. These results suggest that these proteins likely contribute to the meiotic development in dogs.

Oocyte-specific ablation of N- and O-glycans alters cumulus cell signalling and extracellular matrix composition

Cumulus-oocyte complex (COC) expansion is essential for ovulation and fertilisation and is linked to oocyte quality. Hyaluronan (HA), the major matrix constituent, is cross-linked via inter-α-inhibitor heavy chains (HCs), pentraxin 3 (PTX3) and tumour necrosis factor-stimulated gene 6 (TSG-6). All except HCs are secreted by cumulus cells in response to oocyte-secreted factors, which signal via SMAD pathways. The double mutant (DM) mouse generates oocytes lacking complex N- and O-glycans due to oocyte-specific deletion of core 1 β1,3-galactosyltransferase (C1galt1) and N-acetylglucosaminyltransferase I (Mgat1) and has modified cumulus expansion. We compared COCs before expansion (48 h-post-pregnant mare serum gonadotrophin (PMSG)) and at late-stage expansion (9 h-post-human chorionic gonadotrophin (hCG); control n=3 mice, DM n=3 per group). Using histochemistry the levels of HA, HCs, PTX3, TSG-6 and phosphorylated-SMAD1/5/8 and -SMAD2 (12-25 COCs per group) were assessed. DM COCs did not differ from Controls in cumulus size or cell density at 9 h-post-hCG; however, HA and HC levels and phosphorylated-SMAD1/5/8 were reduced. Furthermore, no correlations were found between the levels of matrix molecules and cumulus area in DM or Control samples. These data suggest that HA and HCs can support cumulus expansion provided that they are present above minimum threshold levels. We propose that oocyte-specific ablation of C1galt1 and Mgat1 may affect bone morphogenetic protein 15 synthesis or bioactivity, thereby reducing SMAD1/5/8 phosphorylation and HA production.

Nuclear exclusion of SMAD2/3 in granulosa cells is associated with primordial follicle activation in the mouse ovary

Maintenance and activation of the limited supply of primordial follicles in the ovary are important determinants of reproductive lifespan. Currently, the molecular programme that maintains the primordial phenotype and the early events associated with follicle activation are not well defined. Here, we have systematically analysed these events using microscopy and detailed image analysis. Using the immature mouse ovary as a model, we demonstrate that the onset of granulosa cell (GC) proliferation results in increased packing density on the oocyte surface and consequent GC cuboidalization. These events precede oocyte growth and nuclear translocation of FOXO3a, a transcription factor important in follicle activation. Immunolabelling of the TGFβ signalling mediators and transcription factors SMAD2/3 revealed a striking expression pattern specific to GCs of small follicles. SMAD2/3 were expressed in the nuclei of primordial GCs but were mostly excluded in early growing follicles. In activated follicles, GC nuclei lacking SMAD2/3 generally expressed Ki67. These findings suggest that the first phenotypic changes during follicle activation are observed in GCs, and that TGFβ signalling is fundamental for regulating GC arrest and the onset of proliferation.

Assessing recrudescence of photoregressed Siberian hamster ovaries using in vitro whole ovary culture

In vitro culture has been used to study different aspects of ovarian function; however, this technique has not been applied to study recrudescence, or the return of ovarian function in seasonally breeding species. In Siberian hamsters, exposure to inhibitory photoperiods induces declines in ovarian function, which are restored with photostimulation. Because these changes are mediated by changes in systemic gonadotropin (GT) secretion, we hypothesized that culturing photoregressed ovaries with GT would restore aspects of function and induce expression of key folliculogenic factors. Adult female Siberian hamsters were exposed to either long-day (LD; 16L:8D) or short-day (SD; 8L:16D) photoperiods for 14 weeks to maintain in vivo cyclicity or induce gonadal regression, respectively. Isolated ovaries were then cultured for 10 days with or without GT. Ovarian mass and messenger RNA (mRNA) expression of mitotic marker Pcna were increased in cultured SD ovaries (cSD) ovaries with GT as compared to without GT, with no changes noted among cultured LD (cLD) ovaries. Media estradiol and progesterone concentrations increased in both cLD and cSD ovaries cultured with GT as compared to without GT. No differences in follicle numbers or incidence of apoptosis were noted across groups. In addition, differential mRNA expression of folliculogenic growth factors ( Bmp-4, Ntf-3, Inh-α, Gdf-9, Igf-1, Has-2, and Cox-2) was observed in cSD treated with or without GT. Together, these results suggest that this in vitro model could be a useful tool to (a) study the return of function in photoregressed ovaries, and (b) to identify the specific roles folliculogenic factors play in ovarian recrudescence.

Effect of selenium supplementation on pigeon reproductive performance, selenium concentration and antioxidant status

The effects of dietary supplementation of sodium selenite (SS) on the reproductive performance and the concentration of selenium, glutathione peroxidase (GSH-Px), superoxide dismutase (SOD), and malondialdehyde (MDA) were determined, and expression of glutathione peroxidase 4 (GPx4) and bone morphogenic protein 15 (BMP15) was evaluated. Paired pigeons (n = 864) were fed: T1 received no SS, while T2, T3, and T4 received 0.5, 1.0, and 1.5 mg of SS/kg of dry matter (DM), respectively. Treatments were performed in triplicate with 72 pairs in each replicate. The results showed that selenium supplementation significantly affected pigeon reproductive performance. Birds fed 1.0 mg of SS/kg displayed higher egg production (P > 0.05), higher birth rate, and lower dead sperm rate than the control group (P < 0.05). Selenium and biochemical analyses revealed a higher selenium concentration in the 1.5 mg of SS/kg group than in the control group (P < 0.05), while GSH-Px was higher in the 0.5 mg of SS/kg group than in the control group (P < 0.05). Neither the MDA nor the SOD content were affected significantly in liver, chest muscle, or leg muscle (P > 0.05); however, in plasma, MDA was lower in the control group (P < 0.05), while SOD was higher in the control group (P < 0.05). qRT-PCR results revealed up-regulation of GPx4 in hypothalamus, pituitary and testis tissues in supplemented groups (P < 0.05). However, expression in ovary differed; GPx4 mRNA levels were lower in the 1.5 mg of SS/kg and control groups than in the 1.0 or 0.5 mg of SS/kg groups (P < 0.05). Expression of BMP15 in the hypothalamus, pituitary, and testis tissues was unaffected (P > 0.05), while in ovary, BMP15 was down-regulated in the 1.5 mg of SS/kg group (P < 0.05). These results suggest pigeons supplemented with SS up-regulated GPx4, 1.0 mg of SS/kg exhibited superior reproductive performance, while 1.5 mg of SS/kg increased the selenium concentration, and 0.5 mg of SS/kg up-regulated GSH-Px activity.

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.

Repertoire of bone morphogenetic proteins and growth/differentiation factors in ovary of the Indian wall lizard (Hemidactylus flaviviridis) with emphasis on differential expression and gonadotropic regulation of bmp15 and gdf9

Analysis of ovarian transcriptome of Indian wall lizard demonstrates the existence of several bone morphogenetic proteins (bmp1, 2, 3, 3b, 7, 8, 15) and growth/differentiation factors (gdf5, 9) for the first time in reptilian ovary. The characterization of putative full-length/partial protein sequences of BMPs (BMP2, 3, 3b, 7, 15) and GDF9 showed high homology of their TGF-β domain with that of other vertebrates while BMP1 bore homology to zinc-dependent metalloprotease. Phylogenetic analyses showed clustering of BMPs and GDF9 from wall lizards with that of squamates lying in close proximity to chelonia, crocodilia and aves. This study also correlates the expression of ovarian bmp15 and gdf9 with folliculogenesis. Level of bmp15 dramatically increased with the onset of follicular growth in early recrudescence and attained peak during late recrudescence whereas gdf9 sharply decreased during recrudescence as compared to regression. Nonetheless, expression of these growth factors decreased appreciably with the formation of vitellogenic follicle during breeding phase. Ovarian expression of bmp15 and gdf9 appeared to be regulated by gonadotropin as bmp15 considerably increased while gdf9 decreased in parallel to follicular development after administration of 3 injections of FSH. Expression of both the growth factors declined with the prolongation of treatment that led to formation of early/late vitellogenic follicle. Our in vitro study revealed stimulatory effect of FSH on expression of bmp15 and gdf9 in early growing, previtellogenic and early vitellogenic follicles. In light of in vitro results, FSH-induced in vivo decline in gene expression seems to be due to some other FSH-induced factor.

Regulation of AMH by oocyte-specific growth factors in human primary cumulus cells

The regulation of AMH production by follicular cells is poorly understood. The purpose of this study was to determine the role of the oocyte-secreted factors, growth differentiation factor 9 (GDF9) and bone morphogenetic protein 15 (BMP15), on AMH production in primary human cumulus cells. Cumulus cells from IVF patients were cultured with a combination of GDF9, BMP15, recombinant FSH and specific signaling inhibitors. Stimulation with GDF9 or BMP15 separately had no significant effect on AMH mRNA levels. In contrast, simultaneous stimulation with GDF9 and BMP15 (G + B) resulted in a significant increase in AMH mRNA expression. Increasing concentration of G + B (0.6, 2.5, 5 and 10 ng/mL) stimulated AMH in a dose-dependent manner, showing a maximal effect at 5 ng/mL. Western blot analyses revealed an average 16-fold increase in AMH protein levels in cells treated with G + B when compared to controls. FSH co-treatment decreased the stimulation of AMH expression by G + B. The stimulatory effect of G + B on the expression of AMH was significantly decreased by inhibitors of the SMAD2/3 signaling pathway. These findings show for the first time that AMH production is regulated by oocyte-secreted factors in primary human cumulus cells. Moreover, our novel findings establish that the combination of GDF9 + BMP15 potently stimulates AMH expression.

Effects of bone morphogenetic protein 4 (BMP4) on in vitro development and survival of bovine preantral follicles enclosed in fragments ovarian tissue

The aim of this study was to evaluate the effects of different concentrations of BMP4 on activation, development and mRNA expression of GDF9, BMP15, PCNA, Bax and Bcl2 in cultured bovine follicles enclosed in ovarian tissues. Ovarian tissue fragments were cultured for 6 days in α-MEM+ alone or supplemented with different concentrations of BMP4 (10, 50 or 100 ng/ml). Classical histology was performed to analyze follicle growth and morphology, while real-time PCR was used to analyze mRNA levels in fresh and cultured tissues. After 6 days, the culture of ovarian tissue in α-MEM+ alone or supplemented with 10, 50 or 100 ng/ml BMP4 promoted follicular activation. The different concentrations of BMP4 maintained the percentage of normal follicles similar to results of the control. The presence of 100 ng/ml BMP-4 in culture medium increased oocyte and follicular diameters of primary and secondary follicles when compared with those follicles from uncultured control or cultured in α-MEM+ alone (P < 0.05). The tissues cultured in the presence of increasing concentrations of BMP4 had an increase in mRNA expression of the tested genes, but despite this the differences were not statistically significant. In conclusion, 100 ng/ml BMP4 promotes an increase in diameters of follicles and oocytes of primary and secondary follicles after 6 days of in vitro culture.

Oocyte-somatic cell interactions in the human ovary-novel role of bone morphogenetic proteins and growth differentiation factors

BACKGROUND

Initially identified for their capability to induce heterotopic bone formation, bone morphogenetic proteins (BMPs) are multifunctional growth factors that belong to the transforming growth factor β superfamily. Using cellular and molecular genetic approaches, recent studies have implicated intra-ovarian BMPs as potent regulators of ovarian follicular function. The bi-directional communication of oocytes and the surrounding somatic cells is mandatory for normal follicle development and oocyte maturation. This review summarizes the current knowledge on the physiological role and molecular determinants of these ovarian regulatory factors within the human germline-somatic regulatory loop.

OBJECTIVE AND RATIONALE

The regulation of ovarian function remains poorly characterized in humans because, while the fundamental process of follicular development and oocyte maturation is highly similar across species, most information on the regulation of ovarian function is obtained from studies using rodent models. Thus, this review focuses on the studies that used human biological materials to gain knowledge about human ovarian biology and disorders and to develop strategies for preventing, diagnosing and treating these abnormalities.

SEARCH METHODS

Relevant English-language publications describing the roles of BMPs or growth differentiation factors (GDFs) in human ovarian biology and phenotypes were comprehensively searched using PubMed and the Google Scholar database. The publications included those published since the initial identification of BMPs in the mammalian ovary in 1999 through July 2016.

OUTCOMES

Studies using human biological materials have revealed the expression of BMPs, GDFs and their putative receptors as well as their molecular signaling in the fundamental cells (oocyte, cumulus/granulosa cells (GCs) and theca/stroma cells) of the ovarian follicles throughout follicle development. With the availability of recombinant human BMPs/GDFs and the development of immortalized human cell lines, functional studies have demonstrated the physiological role of intra-ovarian BMPs/GDFs in all aspects of ovarian functions, from follicle development to steroidogenesis, cell–cell communication, oocyte maturation, ovulation and luteal function. Furthermore, there is crosstalk between these potent ovarian regulators and the endocrine signaling system. Dysregulation or naturally occurring mutations within the BMP system may lead to several female reproductive diseases. The latest development of recombinant BMPs, synthetic BMP inhibitors, gene therapy and tools for BMP-ligand sequestration has made the BMP pathway a potential therapeutic target in certain human fertility disorders; however, further clinical trials are needed. Recent studies have indicated that GDF8 is an intra-ovarian factor that may play a novel role in regulating ovarian functions in the human ovary.

WIDER IMPLICATIONS

Intra-ovarian BMPs/GDFs are critical regulators of folliculogenesis and human ovarian functions. Any dysregulation or variations in these ligands or their receptors may affect the related intracellular signaling and influence ovarian functions, which accounts for several reproductive pathologies and infertility. Understanding the normal and pathological roles of intra-ovarian BMPs/GDFs, especially as related to GC functions and follicular fluid levels, will inform innovative approaches to fertility regulation and improve the diagnosis and treatment of ovarian disorders.

Forkhead box O member FOXO1 regulates the majority of follicle-stimulating hormone responsive genes in ovarian granulosa cells

FSH promotes maturation of ovarian follicles. One pathway activated by FSH in granulosa cells (GCs) is phosphatidylinositol-3 kinase/AKT. The AKT target FOXO1 is reported to function primarily as a repressor of FSH genes, including Ccnd2 and Inha. Based on its broad functions in other tissues, we hypothesized that FOXO1 may regulate many more GC genes. We transduced GCs with empty adenovirus or constitutively active FOXO1 followed by treatment with FSH for 24 h, and conducted RNA deep sequencing. Results show that FSH regulates 3772 genes ≥2.0-fold; 60% of these genes are activated or repressed by FOXO1. Pathway Studio Analysis revealed enrichment of genes repressed by FOXO1 in metabolism, signaling, transport, development, and activated by FOXO1 in signaling, cytoskeletal functions, and apoptosis. Gene regulation was verified by q-PCR (eight genes) and ChIP analysis (two genes). We conclude that FOXO1 regulates the majority of FSH target genes in GCs.

The Hippo/MST Pathway Member SAV1 Plays a Suppressive Role in Development of the Prehierarchical Follicles in Hen Ovary

The Hippo/MST signaling pathway is a critical player in controlling cell proliferation, self-renewal, differentiation, and apoptosis of most tissues and organs in diverse species. Previous studies have shown that Salvador homolog 1 (SAV1), a scaffolding protein which functions in the signaling system is expressed in mammalian ovaries and play a vital role in governing the follicle development. But the exact biological effects of chicken SAV1 in prehierarchical follicle development remain poorly understood. In the present study, we demonstrated that the SAV1 protein is predominantly expressed in the oocytes and undifferentiated granulosa cells in the various sized prehierarchical follicles of hen ovary, and the endogenous expression level of SAV1 mRNA appears down-regulated from the primordial follicles to the largest preovulatory follicles (F2-F1) by immunohistochemistry and real-time RT-PCR, respectively. Moreover, we found the intracellular SAV1 physically interacts with each of the pathway members, including STK4/MST1, STK3/MST2, LATS1 and MOB2 using western blotting. And SAV1 significantly promotes the phosphorylation of LATS1 induced by the kinase of STK4 or STK3 in vitro. Furthermore, SAV1 knockdown by small interfering RNA (siRNA) significantly increased proliferation of granulosa cells from the prehierarchical follicles (6-8 mm in diameter) by BrdU-incorporation assay, in which the expression levels of GDF9, StAR and FSHR mRNA was notably enhanced. Meanwhile, these findings were consolidated by the data of SAV1 overexpression. Taken together, the present results revealed that SAV1 can inhibit proliferation of the granulosa cells whereby the expression levels of GDF9, StAR and FSHR mRNA were negatively regulated. Accordingly, SAV1, as a member of the hippo/MST signaling pathway plays a suppressive role in ovarian follicle development by promoting phosphorylation and activity of the downstream LATS1, may consequently lead to prevention of the follicle selection during ovary development.

Temporal expression of GDF-9 and BMP-15 mRNAs in canine ovarian follicles

This study aimed to investigate the expression profiles of growth differentiation factor 9 (GDF-9) and bone morphogenetic protein 15 (BMP-15) mRNA in canine oocytes and follicular cells throughout development at the different phases of the estrus cycle. Ovarian structures (follicles and CL) and plasma progesterone concentration were used to confirm the physiological status of each donor. Denuded oocytes and their follicular cells were recovered from follicles (n = 675) distributed into 4 types (preantral, small antral ∼0.2-0.39 mm, medium antral ∼0.4-5.9 mm, and large antral ∼6-8 mm). Total RNA was extracted and reverse transcribed, and the levels of expression for these 2 genes were determined using a quantitative real-time polymerase chain reaction technique; the data were evaluated by ANOVA. Relative expressions levels of GDF-9 and BMP-15 transcripts were detected in the oocyte and follicular cells in all follicular stages evaluated, showing differential changes (P < 0.05) during development over the estrus cycle. The expression patterns of both transcripts were highly correlated between follicles cells and oocytes (r > 0.8; P < 0.05 for GDF-9 and BMP-15), although GDF-9 was expressed at higher levels (P < 0.05) in the oocyte compared with the follicle cells. All cell types showed more GDF-9 mRNA abundance at early developing stages, mainly in the anestrus phase, and declining levels in the later stages (P < 0.05), whereas BMP-15 mRNA levels increased (P < 0.05) in follicular cells and oocytes from the preantral to the later stages, and remained constant during the final preovulatory stage. In conclusion, these two genes were detected in follicular cells and oocytes and were differentially expressed during the follicular development across the estrus cycle.

Growth and differentiation factor 9 promotes oocyte growth at the primary but not the early secondary stage in three-dimensional follicle culture

PURPOSE

Factors that differentially regulate oocyte and granulosa cell growth within the early preantral follicle and how these factors differ at each stage of follicle growth remain poorly understood. The aim of this study was to isolate and evaluate the effect of recombinant growth and differentiation factor 9 (GDF9) on oocyte and granulosa cell growth at the primary and early secondary stages of preantral follicle growth during in vitro culture.

METHODS

Primary stage follicles (diameters of 50-89 μm) and early secondary stage follicles (diameters of 90-120 μm) were isolated from immature mice, and individual, intact follicles were cultured in vitro in the presence and absence of recombinant GDF9. The effects of GDF9 on follicle growth were determined by the assessment of changes in the follicle volume during culture. The growth of the granulosa cell and oocyte compartments of the follicles was evaluated separately at each stage.

RESULTS

GDF9 significantly increased the growth of isolated follicles at both the primary and early secondary follicle stages. Independent evaluation of the granulosa cell and oocyte compartments revealed that, while GDF9 promoted granulosa cell growth at both stages of folliculogenesis, oocyte growth was stage specific. GDF9 promoted growth of the oocyte at the primary, but not the early secondary, follicle stage.

CONCLUSIONS

These findings demonstrate a stage-specific role for GDF9 in the regulation of oocyte and granulosa cell growth at the primary and early secondary stages of preantral follicle development.

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.

Simulated Microgravity Using a Rotary Culture System Compromises the In Vitro Development of Mouse Preantral Follicles

Background

Growing cells in simulated weightlessness condition might be a highly promising new technique to maintain or generate tissue constructs in a scaffold-free manner. There is limited evidence that microgravity condition may affect development of ovarian follicles. The objective of the present study was to investigate the effects of simulated microgravity on the in vitro development of mouse preantral follicles.

Methods and Results

Ovarian tissue from 14-day-old mice, or preantral follicles mechanically isolated from 14-day-old mouse ovaries were cultured at a simulated microgravity condition generated using a rotating wall vessel apparatus. Follicle survival was assessed quantitatively using H&E staining. Follicle diameter and oocyte diameter were measured under an inverted microscope. Ultrastructure of oocytes was evaluated using transmission electron microscopy. We observed that simulated microgravity compromised follicle survival in vitro, downregulated PCNA and GDF-9 expressions, and caused ultrastructural abnormalities in oocytes.

Conclusion

This study showed for the first time that three-dimensional culture condition generated by simulated microgravity is detrimental to the initial stage development of mouse preantral follicles in vitro. The experimental setup provides a model to further investigate the mechanisms involved in the in vitro developmental processes of oocytes/granulosa cells under the microgravity condition.