Expression of GDF-9, BMP-15 and their receptors in mammalian ovary follicles

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.

Transcriptomic Analysis Reveals Differentially Expressed Circular RNAs Associated with Fecundity in the Sheep Hypothalamus with Different FecB Genotypes

Circular RNAs (circRNAs) are a specific type of noncoding RNA, and some have defined roles in cellular and biological processes. However, little is known about the role of circRNAs in follicular development in sheep with FecB (fecundity Booroola) mutations. Here, the expression profiles of circRNAs were investigated using RNA sequencing (RNA-seq) in the follicular phase (F) and the luteal phase (L) of FecB mutant homozygous (BB) and wild-type (WW) Small Tail Han sheep. A total of 38,979 circRNAs were identified, and 314, 343, 336, and 296 of them were differentially expressed (DE) between BB_F and BB_L, WW_F and WW_L, BB_F and WW_F, and BB_L and WW_L, respectively. The length, type, and chromosome distribution of the circRNAs and the expression characteristic between the circRNAs and their host genes in the sheep hypothalamus were ascertained. Enrichment analysis showed that the host genes of DE circRNAs in the follicular and luteal phases were annotated to MAPK, gap junctions, progesterone-mediated oocyte maturation, oocyte meiosis, and other hormone-related signaling pathways, and the different FecB genotypes were annotated to the gap junctions, circadian entrainment, MAPK, and other hormone-related signaling pathways. The competing endogenous RNA network prediction revealed that the 129 target miRNAs might be bound to 336 DE circRNAs. oar_circ_0000523 and oar_circ_0028984, which were specifically expressed during the follicular phase in the BB genotype sheep, probably acted as miRNA sponges involved in the regulation of LH synthesis and secretion. This study reveals the expression profiles and characterization of circRNAs at two phases of follicular development considering different FecB genotypes, thereby providing an improved understanding of the roles of circRNAs in the sheep hypothalamus and their involvement in follicular development and ovulation.

In-vitro generation of follicle-like structures from human germ cell-like cells derived from theca stem cell combined with ovarian somatic cells

BACKGROUND

The objective of this study was to induce the differentiation of human theca stem cells (hTSCs) into germ cell-like cells (hGCLCs) and assess their developmental progression following in vitro 3D culture with ovarian somatic cells within the follicle-like structures. To achieve this, the hTSCs were isolated from small antral follicles of three patients of varying ages and were then seeded in a differentiation medium for 40 days. The differentiated hGCLCs were subsequently aggregated with somatic ovarian cells (cumulus cells and hTSCs) in a ratio of 1:10 and cultured in a growth medium in a suspension culture dish. In addition to examining the morphologies, sizes, and viabilities of the differentiated hGCLCs, this study also analyzed the expression of DAZL and GDF9 proteins within the follicle-like structures.

RESULTS

After 12 days, the hTSCs began to differentiate into hGCLCs, with their shapes changing from spindle-shaped to spherical. The sizes of hGCLCs increased during the differentiation period (from 25 μm to 50 μm). The survival rate of the hGCLCs after differentiation and in vitro development in primordial follicle-like structures was 54%. Unlike hTSCs, which did not express the DAZL protein, the hGCLCs and follicle-like structures successfully expressed DAZL protein (P-value < 0.05). However, hGCLCs poorly expressed the GDF9 protein. Further, the culture of hGCLCs in primordial follicle-like structures significantly increased GDF9 expression (P-value < 0.05).

CONCLUSION

In conclusion, our study demonstrated that 3D cultures with ovarian somatic cells in follicle-like structures caused the successful differentiation of reproducible hGCLCs from hTSCs derived from three patients of different ages. Moreover, this method not only enhanced the in vitro development of hGCLCs but also presented a novel approach for co-culturing and developing in vitro oocyte like cells, ultimately leading to the production of artificial follicles.

Inactivation of growth differentiation factor 9 blocks folliculogenesis in pigs†

Growth differentiation factor 9 (GDF9) is a secreted protein belonging to the transforming growth factor beta superfamily and has been well characterized for its role during folliculogenesis in the ovary. Although previous studies in mice and sheep have shown that mutations in GDF9 disrupt follicular progression, the exact role of GDF9 in pigs has yet to be elucidated. The objective of this study was to understand the role of GDF9 in ovarian function by rapidly generating GDF9 knockout (GDF9-/-) pigs by using the CRISPR/Cas9 system. Three single-guide RNAs designed to disrupt porcine GDF9 were injected with Cas9 mRNA into zygotes, and blastocyst-stage embryos were transferred into surrogates. One pregnancy was sacrificed on day 100 of gestation to investigate the role of GDF9 during oogenesis. Four female fetuses were recovered with one predicted to be GDF9-/- and the others with in-frame mutations. All four had fully formed oocytes within primordial follicles, confirming that knockout of GDF9 does not disrupt oogenesis. Four GDF9 mutant gilts were generated and were grown past puberty. One gilt was predicted to completely lack functional GDF9 (GDF9-/-), and the gilt never demonstrated standing estrus and had a severely underdeveloped reproductive tract with large ovarian cysts. Further examination revealed that the follicles from the GDF9-/- gilt did not progress past preantral stages, and the uterine vasculature was less extensive than the control pigs. By using the CRISPR/Cas9 system, we demonstrated that GDF9 is a critical growth factor for proper ovarian development and function in pigs.

Endometrial cell-derived conditioned medium in combination with platelet-rich plasma promotes the development of mouse ovarian follicles

Fertility preservation is one of the most important issues in assisted reproductive technology. Previous studies have shown that cytokines and growth factors can improve follicle growth. The endometrial stromal cells secrete various factors that are involved in maintaining the integrity of uterine and epithelial secretory function. The platelet-rich plasma contains a large assembly of platelets suspended in plasma that successfully improves the viability and growth of various cell lines. This work aimed to investigate the influences of conditioned medium (CM) and platelet-rich plasma (PRP) on the development of ovarian follicles in infertile mice due to cyclophosphamide (CYC) exposure. In this study, 65 healthy BALB/c female mice (∼28-30 g and 6-8 weeks old) in five groups were studied. Immunohistochemistry (IHC) was used to detect growth differentiation factor 9 (GDF9)-positive cells. The mRNA expression levels of SMAD1, SMAD2, and BMP15 was assessed using reverse transcription-polymerase chain reaction (RT-PCR) method. The expression levels of SMAD1, GDF9, BMP15, and SMAD2 in the CM+PRP group was significantly more than in the CM and PRP groups. In addition, live birth occurred in the CM+PRP group. Treatment with CM+PRP in infertile mice due to Cy exposure increased fertility and live-birth rate. In general, our study suggested that the CM and PRP combination could improve the growth of mice ovarian follicles in vivo.

Expression Patterns and Gonadotropin Regulation of the TGF-β II Receptor (Bmpr2) during Ovarian Development in the Ricefield Eel Monopterus albus

Bmpr2 plays a central role in the regulation of reproductive development in mammals, but its role during ovarian development in fish is still unclear. To ascertain the function of bmpr2 in ovarian development in the ricefield eel, we isolated and characterized the bmpr2 cDNA sequence; the localization of Bmpr2 protein was determined by immunohistochemical staining; and the expression patterns of bmpr2 in ovarian tissue incubated with FSH and hCG in vitro were analyzed. The full-length bmpr2 cDNA was 3311 bp, with 1061 amino acids encoded. Compared to other tissues, bmpr2 was abundantly expressed in the ovary and highly expressed in the early yolk accumulation (EV) stages of the ovary. In addition, a positive signal for Bmpr2 was detected in the cytoplasm of oocytes in primary growth (PG) and EV stages. In vitro, the expression level of gdf9, the ligand of bmpr2, in the 10 ng/mL FSH treatment group was significantly higher after incubation for 4 h than after incubation for different durations. However, bmpr2 expression in the 10 ng/mL FSH treatment group at 2 h, 4 h and 10 h was significantly lower. Importantly, the expression level of bmpr2 and gdf9 in the 100 IU/mL hCG group had similar changes that were significantly decreased at 4 h and 10 h. In summary, Bmpr2 might play a pivotal role in ovarian growth in the ricefield eel, and these results provide a better understanding of the function of bmpr2 in ovarian development and the basic data for further exploration of the regulatory mechanism of gdf9 in oocyte development.

Regulatory Role and Potential Importance of GDF-8 in Ovarian Reproductive Activity

Growth differentiation factor-8 (GDF-8) is a member of the transforming growth factor-beta superfamily. Studies in vitro and in vivo have shown GDF-8 to be involved in the physiology and pathology of ovarian reproductive functions. In vitro experiments using a granulosa-cell model have demonstrated steroidogenesis, gonadotrophin responsiveness, glucose metabolism, cell proliferation as well as expression of lysyl oxidase and pentraxin 3 to be regulated by GDF-8 via the mothers against decapentaplegic homolog signaling pathway. Clinical data have shown that GDF-8 is expressed widely in the human ovary and has high expression in serum of obese women with polycystic ovary syndrome. GDF-8 expression in serum changes dynamically in patients undergoing controlled ovarian hyperstimulation. GDF-8 expression in serum and follicular fluid is correlated with the ovarian response and pregnancy outcome during in vitro fertilization. Blocking the GDF-8 signaling pathway is a potential therapeutic for ovarian hyperstimulation syndrome and ovulation disorders in polycystic ovary syndrome. GDF-8 has a regulatory role and potential importance in ovarian reproductive activity and may be involved in folliculogenesis, ovulation, and early embryo implantation.

PCOS and Role of Cumulus Gene Expression in Assessing Oocytes Quality

The global infertility rate has been declining from year to year. PCOS is one of the treatable accountable causes contributing to anovulatory infertility. Nevertheless, the success rate of treatments and live-birth outcomes especially involving assisted reproductive techniques is still not very promising. There is a reduction in the development potential of oocytes and high-quality embryos in PCOS patients compared to non-PCOS patients. A critical step in IVF treatment is the assessment of oocyte and embryo competence before embryo transfer. Oocytes in metaphase II are very fragile. Repeated morphological assessment on these oocytes may directly impair the quality and affect the whole process. Identification of potential biomarkers especially in the cumulus cells oocytes complex will help to predict the outcome and may create space for improvement. This review has explored gene expression in cumulus cells with regards to oocytes quality in both normal and PCOS women. The gene expression was classified according to their physiological function such as the contribution on cumulus expansion, cumulus cells apoptosis, and glucose metabolism. Collectively, the review suggested that positive expression of HAS2, PTX3, GREM1, and VCAN may correlate with good quality oocytes and can be used as an indicator among PCOS women.

Estradiol Upregulates the Expression of the TGF-β Receptors ALK5 and BMPR2 during the Gonadal Development of Schizothorax prenanti

Simple Summary

Schizothorax prenanti, known as the ya-fish, is mainly distributed in regions adjacent to the Qinghai-Tibet Plateau (QTP) and is an endemic fish species with great economic importance in aquaculture in Western China. In the present study, we were aimed to explore the functions of ALK5 and BMPR2 during the gonadal development of S. prenanti. Our results suggest that ALK5 and BMPR2 may play a potentially vital role in both folliculogenesis and spermatogenesis in S. prenanti.

Abstract

TGF-β receptors play important roles in mediating TGF-β signals during gonadal development. To identify the functions of TGF-β receptors, including the type I receptor (activin receptor-like kinase 5, ALK5) and type II receptor (bone morphogenetic protein receptor 2, BMPR2), during the gonadal development of S. prenanti, the full-length cDNA sequences of ALK5 and BMPR2 were isolated and characterized. Their expression patterns in developing gonads and in the gonads of exogenous estradiol (E₂) -fed fish were analyzed. The cDNAs of ALK5 and BMPR2 were 1925 bp and 3704 bp in length and encoded 501 and 1070 amino acid residues, respectively. ALK5 and BMPR2 were mostly expressed in gonads, particularly in cortical alveoli stage ovaries and mid-spermatogenic stage testes; however, the overall level of BMPR2 mRNA was higher than that of ALK5 during gonadal development. Furthermore, immunohistochemical signals of ALK5 and BMPR2 were mostly detected at chromatin nucleolar oocytes and perinuclear oocytes in ovaries and at spermatocytes and spermatogonia in testes. Exogenous E₂ induces the gonadal expression of ALK5 and BMPR2, and BMPR2 is more responsive to E₂ than ALK5. These results suggest that ALK5 and BMPR2 might play a potentially vital role in both folliculogenesis and spermatogenesis in S. prenanti.

New insights into the GDF9-Hedgehog-GLI signaling pathway in human ovaries: from fetus to postmenopause

RESEARCH QUESTION

Are glioma-associated oncogene homolog 1, 2, and 3 (GLI1, 2, and 3) and protein patched homolog 1 (PTCH1) specific markers for precursor theca cells in human ovaries as in mouse ovaries?

DESIGN

To study the GDF9-HH-GLI pathway and assess whether GLI1 and 3 and PTCH1 are specific markers for precursor theca cells in the human ovary, growth differentiation factor 9 (GDF9), Indian Hedgehog (IHH), Desert Hedgehog (DHH), Sonic Hedgehog (SHH), PTCH1 and GLI1, 2 and 3 were investigated in fetal (n=9), prepubertal (n=9), reproductive-age (n=15), and postmenopausal (n=8) human ovarian tissue. Immunohistochemistry against GDF9, IHH, DHH, SHH, PTCH1, GLI1, GLI2, and GLI3 was performed on human ovarian tissue sections fixed in 4% formaldehyde and embedded in paraffin. Western blotting was carried out on extracted proteins from the same samples used in the previous step to prove the antibodies' specificity. The quantitative real-time polymerase chain reaction was performed to identify mRNA levels for Gdf9, Ihh, Gli1, Gli2, and Gli3 in menopausal ovaries.

RESULTS

Our results showed that, in contrast to mice, all studied proteins were expressed in primordial follicles of fetal, prepubertal, and reproductive-age human ovaries and stromal cells of reproductive-age and postmenopausal ovaries. Intriguingly, Gdf9, Ihh, and Gli3 mRNA, but not Gli1 and 2, was detected in postmenopausal ovaries. Moreover, GLI1, GLI3, and PTCH1 are not limited to a specific population of cells. They were spread throughout the organ, which means they are not specific markers for precursor theca cells in human ovaries.

CONCLUSION

These results could provide a basis for understanding how this pathway modulates follicle development and ovarian cell steroidogenesis in human ovaries.

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.

In vitro maturation on ovarian granulosa cells encapsulated in agarose matrix improves developmental competence of porcine oocytes

In vivo, mammalian oocytes are surrounded by granulosa cells (GCs) that exist in a three-dimensional (3D) microenvironment with soft stiffness. The GCs play an important role for the in vivo growth and development of oocytes, through bidirectional communication between oocytes and GCs. To mimic the cellular microenvironment of a 3D organized follicle, this study designed a co-culture system using porcine ovarian GCs (pGCs) encapsulated in agarose matrix for in vitro maturation (IVM) of pig oocytes. We report the effects of our newly designed co-culture system on IVM and development of pig oocytes. Immature cumulus-oocyte-complexes (COCs) were matured on a 1% (w/v) agarose matrix encapsulated without or with pGCs. The number of pGCs within the agarose matrix was optimized by analyzing the in vitro development of parthenogenetic embryos. Moreover, the role of the ovarian stromal pGCs as feeder cells was assessed by analyzing the PA embryonic development. Subsequently, the effect of pGCs encapsulated in a 3D agarose matrix was evaluated for the developmental competence of pig oocytes by analyzing blastocyst formation after parthenogenetic activation (PA), intra-oocyte GSH and ROS contents, expression levels of BMP15 and BAX, TUNEL (terminal deoxynucleotidyl transferase-mediated d-UTP nick end-labeling) assay, protein expression levels of BMP15, and intra-oocyte ATP levels. The optimized number of pGCs (5 × 10⁴ cells/well) in a 3D agarose matrix led to a significantly higher blastocyst formation, increased BMP15 gene and protein expression, and intra-oocyte ATP levels; moreover, it induced significantly lower intra-oocyte ROS contents, pro-apoptotic BAX gene expression, and apoptotic index, compared to control. Our results demonstrate that application of pGCs as feeder cells encapsulated in the agarose matrix for IVM effectively increases the developmental competence of porcine oocytes.

Cyclooxygenase 2 messenger RNA levels in canine follicular cells: interrelationship with GDF-9, BMP-15, and progesterone

Cyclooxygenase 2 (COX-2) encoded by the Cox-2 gene within the periovulatory follicles is a critical mediator of oocyte development. Growth differentiation factor 9 (GDF-9) and bone morphogenetic protein 15 (BMP-15) participate in the modulation of certain target genes in the ovary, possibly influencing the Cox-2 gene expression. However, this relationship has not been characterized in canines. This study aimed to examine the possible relationships among BMP-15, GDF-9, progesterone, and Cox-2 gene expression in granulosa-cumulus cells in dogs. Granulosa cells from antral follicles and their corresponding cumulus-oocyte complexes and follicular fluid (FF) were separately obtained from 56 ovaries collected from adult bitches at estrus (n = 15) and proestrus (n = 13) after ovariohysterectomy. Total RNA extraction was performed in follicular cells, and Cox-2 gene expression was assessed by quantitative PCR analysis. Progesterone, BMP-15, and GDF-9 were determined in the FF samples using ELISA assays. Cumulus-oocyte complexes were subjected to in vitro maturation (IVM) with or without (control) recombinant GDF-9 and BMP-15. After 72 h of culture, Cox-2 transcript analyses were performed in cumulus cells via quantitative PCR. Data were evaluated by ANOVA. An increase (P < 0.05) in Cox-2 messenger RNA levels was observed in follicular cells from follicles at estrus with respect to those at proestrus. However, the levels of BMP-15 and GDF-9 in FF decreased (P < 0.05), whereas progesterone increased (P < 0.05) from the proestrus phase to the estrus phase. The expression of Cox-2 gene in cumulus cells was 4-fold greater (P < 0.01) than that in the control when both growth factors were added to the IVM culture. In conclusion, although BMP-15 together with GDF-9 appears to upregulate the levels of Cox-2 transcripts during IVM, the inverse relationship of these paracrine factors with Cox-2 gene expression and the positive correlation of progesterone with Cox-2 transcripts suggest that the high progesterone levels could be more relevant in the local mechanisms regulating the Cox-2 gene expression.

Study on the correlation between BMPR1B protein in sheep blood and reproductive performance

Sheep reproductive performance is one of the important economic traits in sheep farming. The bone morphogenetic protein receptor 1B (BMPR1B) gene and protein may play an important role in sheep fertility. This study was to investigate the association of blood BMPR1B protein expression with reproductive performance in sheep. Mongolian sheep with single and twin births and polytocous Small Tail Han sheep were selected due to differences in birth numbers. The BMPR1B mRNA in sheep blood was measured by a reverse transcription-polymerase chain reaction as well as the BMPR1B protein was measured by enzyme-linked immunosorbent assay in blood samples of Mongolian and Small Tail Han sheep. The results demonstrated that blood BMPR1B concentration in Mongolian sheep with twin birth was higher (P < 0.05) than Small Tail Han sheep and Mongolian sheep with single birth. The protein concentration in the anestrus season was higher (P < 0.045) than those in the estrus season for both Mongolian and Small Tail Han sheep. Moreover, BMPR1B concentration in Mongolian sheep increased (P < 0.05) at the age of 6 to 12 mo and that in Small Tail Han sheep increased (P < 0.05) at the age of 3 to 6 mo. The result indicates that the increase in BMPR1B protein concentrations in the blood of Mongolian ewes and Small Tail Han ewes may be beneficial to follicular development, but too high or too low of this blood protein concentration in Mongolian and Small Tail Han sheep is not conducive to ovulation.

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.

A Gatekeeping Role of ESR2 to Maintain the Primordial Follicle Reserve

Over the entire reproductive lifespan in mammals, a fixed number of primordial follicles serve as the source of mature oocytes. Uncontrolled and excessive activation of primordial follicles can lead to depletion of the ovarian reserve. We observed that disruption of estrogen receptor β (ESR2) signaling results in increased activation of primordial follicles in Esr2-null (Esr2-/-) rats. However, follicle assembly was unaffected, and the total number of follicles remained comparable between neonatal wild-type and Esr2-/- ovaries. While the activated follicle counts were increased in Esr2-/- ovary, the number of primordial follicles were markedly decreased. Excessive recruitment of primordial follicles led to premature ovarian senescence in Esr2-/- rats and was associated with reduced levels of serum AMH and estradiol. Disruption of ESR2 signaling through administration of a selective antagonist (PHTPP) increased the number of activated follicles in wildtype rats, whereas a selective agonist (DPN) decreased follicle activation. In contrast, primordial follicle activation was not increased in the absence of ESR1, indicating that the regulation of primordial follicle activation is ESR2 specific. Follicle activation was also increased in Esr2 mutants lacking the DNA binding domain, suggesting a role for the canonical transcriptional activation function. Both primordial and activated follicles express ESR2, suggesting a direct regulatory role for ESR2 within these follicles. We also detected that loss of ESR2 augmented the activation of AKT, ERK, and mTOR pathways. Our results indicate that the lack of ESR2 upregulated both granulosa and oocyte factors, which can facilitate AKT and mTOR activation in Esr2-/- ovaries leading to increased activation of primordial follicles.

Prediction of ovarian aging using ovarian expression of BMP15, GDF9, and C-KIT

IMPACT STATEMENT

Ovarian aging is becoming a more important issue in terms of fertility preservation and infertility treatment. Serum anti-Mullerian hormone (AMH) level and antral follicle count (AFC) are being practically used as markers of ovarian aging as well as ovarian reserve in human. However, these factors have some drawbacks in assessing ovarian aging and reserve. Therefore, the identification of ovarian expressions of BMP15, GDF9, and C-KIT according to female could be applied as a potent predictor of ovarian aging. This work provides new information on the development of diagnosis and treatment strategy of age-related fertility decline and premature ovarian insufficiency.

The antioxidant curcumin postpones ovarian aging in young and middle-aged mice

Reproductive senescence is accompanied by a reduced number and quality of ovarian follicles in response to the accumulation of free radicals and the process of apoptosis. Having selected mice as models, we examined the hypothesis that curcumin as an antioxidant and anti-inflammatory agent might prevent or retard ovarian aging. Female NMRI 21-day-old mice were divided into control, vehicle and curcumin groups. In the treatment group the mice received curcumin at 100mgkg-1day-1 intraperitoneally. After 6, 12 and 33 weeks several parameters were examined including ovarian reserve, oocyte quality, oxidative status, invitro fertilisation and expression of ovulation-related (growth differentiation factor 9 (GDF-9) and bone morphogenetic protein 15 (BMP-15)) and anti-aging-related (sirtuin 1 (SIRT-1) and SIRT-3) genes. Curcumin treatment up to 12 and 33 weeks resulted in increased ovarian volume and number of follicles and was associated with elevated anti-Müllerian hormone and oestrogen and diminished FSH serum levels. Furthermore, enhanced oocyte maturation, fertilisation and embryo development plus reduced oxidative stress were seen in the curcumin group. Also, the expression of GDF-9, BMP-15, SIRT-1 and SIRT-3 genes was increased in the curcumin group. Concerning gestational age, the findings of the study suggested that administration of curcumin could delay the process of oocyte aging in a mouse model.

Bone Morphogenetic Protein 15 Knockdown Inhibits Porcine Ovarian Follicular Development and Ovulation

Bone morphogenetic protein 15 (BMP15) is strongly associated with animal reproduction and woman reproductive disease. As a multifunctional oocyte-specific secret factor, BMP15 controls female fertility and follicular development in both species-specific and dosage-sensitive manners. Previous studies found that BMP15 played a critical role in follicular development and ovulation rate in mono-ovulatory mammalian species, especially in sheep and human, but study on knockout mouse model implied that BMP15 possibly has minimal impact on female fertility of poly-ovulatory species. However, this needs to be validated in other poly-ovulatory species. To investigate the regulatory role of BMP15 on porcine female fertility, we generated a BMP15-knockdown pig model through somatic nuclear transfer technology. The BMP15-knockdown gilts showed markedly reduced fertility accompanied by phenotype of dysplastic ovaries containing significantly declined number of follicles, increased number of abnormal follicles, and abnormally enlarged antral follicles resulting in disordered ovulation, which is remarkably different from the unchanged fertility observed in BMP15 knockout mice. Molecular and transcriptome analysis revealed that the knockdown of BMP15 significantly affected both granulosa cells (GCs) and oocytes development, including suppression of cell proliferation, differentiation, and follicle stimulating hormone receptor (Fshr) expression, leading to premature luteinization and reduced estradiol (E2) production in GCs, and simultaneously decreased quality and meiotic maturation of oocyte. Our results provide in vivo evidence of the essential role of BMP15 in porcine ovarian and follicular development, and new insight into the complicated regulatory function of BMP15 in female fertility of poly-ovulatory species.

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.

Growth differentiation factor-9 improves development, mitochondrial activity and meiotic resumption of sheep oocytes after in vitro culture of secondary follicles

This study analysed the effect of growth differentiation factor-9 (GDF-9) on the in vitro culture of isolated ovine secondary follicles. The follicles were cultured in α-MEM supplemented with BSA, insulin, glutamine, hypoxanthine, transferrin, selenium, ascorbic acid and FSH (α-MEM⁺ -control medium) or α-MEM⁺ supplemented with 1, 10, 50 or 100 ng/ml GDF-9. Next, the oocytes were destined to in vitro maturation (IVM). After 12 days of culture, there were no differences regarding the percentage of normal follicles, antrum formation and follicle diameter between the treatments (p > 0.05). The rates of fully grown oocytes (≥110 µm) were higher (p < 0.05) in 100 ng/ml GDF-9 than other treatments, except for 10 ng/ml of GDF-9 (p > 0.05). Treatment containing 100 ng/ml GDF-9 showed higher (p < 0.05) mitochondrial activity than the control group. Moreover, 100 ng/ml GDF-9 showed more oocytes in MI than α-MEM⁺ , 1 or 50 ng/ml GDF-9 (p < 0.05). In conclusion, 100 ng/ml GDF-9 increased the growth, mitochondrial function and meiotic resumption of oocytes from in vitro grown sheep secondary follicles.

Neonatal exposure to agonists and antagonists of sex steroid receptors induces changes in the expression of oocyte-derived growth factors and their receptors in ovarian follicles in gilts

The objective of the present study was to examine the effects of neonatal exposure to either agonists or antagonists of androgen and estrogen receptors on the expression of growth and differentiation factor 9 (GDF9) and bone morphogenetic protein 15 (BMP15) and their cognate receptors (TGFBR1, BMPR1B, and BMPR2) in ovarian follicles of adult pigs. Piglets were injected subcutaneously with testosterone propionate (TP, an androgen, at 20 mg/kg bw), flutamide (FLU, an antiandrogen, at 50 mg/kg bw), 4-tert-octylphenol (OP, an estrogenic compound, 100 mg/kg bw), ICI 182,780 (ICI, an antiestrogen, 400 μg/kg bw), or corn oil (control) between postnatal Days 1 and 10 (n = 5/group). Ovarian follicles were excised from adult pigs on Days 8-11 of the estrous cycle. The expression of GDF9, BMP15, TGFBR1, BMPR1B and BMPR2 were examined in the population of preantral and small antral ovarian follicles using real-time PCR, Western blot and immunohistochemistry. In preantral follicles, the upregulation of GDF9 mRNA and protein expression was found in pigs that were neonatally exposed to TP or FLU, while administration of TP or ICI resulted in upregulation of BMP15. TGFBR1 and BMPR2 mRNA and protein expression were upregulated in preantral follicles of adult pigs that were neonatally exposed to TP or FLU, while administration of TP or ICI resulted in upregulation of BMPR1B. In small antral follicles, the mRNA and protein for TGFBR1 and BMPR2 were upregulated, while BMPR1B was downregulated in response to neonatal OP treatment. In addition, treatment with FLU upregulated BMPR1B and BMPR2 mRNA and protein expression, while downregulated the expression of TGFBR1. Moreover, GDF9 and BMP15 were immunolocalized in oocytes and granulosa cells of preantral follicles obtained from both control and treated ovaries. TGFBR1, BMPR1B and BMPR2 receptors were observed in the oocytes and granulosa cells of preantral follicles as well as in granulosa and theca cells of small antral follicles. In conclusion, the present study demonstrated neonatal exposure to either agonists or antagonists of androgen and estrogen receptors affected GDF9 and BMP15 signalling in ovaries of adult pigs. It seems that neonatal androgen excess or deficiency may lead to the acceleration of initial follicle recruitment, while neonatal exposure to compounds with antiandrogenic and estrogenic activity may disturb small antral follicles fate. Therefore, it confirms that neonatal window is critical for programming of ovarian function in pigs.

Three-dimensional organization of transzonal projections and other cytoplasmic extensions in the mouse ovarian follicle

Each mammalian oocyte is nurtured by its own multi-cellular structure, the ovarian follicle. We used new methods for serial section electron microscopy to examine entire cumulus and mural granulosa cells and their projections in mouse antral ovarian follicles. Transzonal projections (TZPs) are thin cytoplasmic projections that connect cumulus cells to the oocyte and are crucial for normal oocyte development. We studied these projections in detail and found that most TZPs do not reach the oocyte, and that they often branch and make gap junctions with each other. Furthermore, the TZPs that connect to the oocyte are usually contacted on their shaft by oocyte microvilli. Mural granulosa cells were found to possess randomly oriented cytoplasmic projections that are strikingly similar to the free-ended TZPs. We propose that granulosa cells use cytoplasmic projections to search for the oocyte, and cumulus cell differentiation results from a contact-mediated paracrine interaction with the oocyte.

Consequences of BMPR2 Deficiency in the Pulmonary Vasculature and Beyond: Contributions to Pulmonary Arterial Hypertension

Since its association with familial pulmonary arterial hypertension (PAH) in 2000, Bone Morphogenetic Protein Receptor II (BMPR2) and its related signaling pathway have become recognized as a key regulator of pulmonary vascular homeostasis. Herein, we define BMPR2 deficiency as either an inactivation of the receptor, decreased receptor expression, or an impairment of the receptor’s downstream signaling pathway. Although traditionally the phenotypic consequences of BMPR2 deficiency in PAH have been thought to be limited to the pulmonary vasculature, there is evidence that abnormalities in BMPR2 signaling may have consequences in many other organ systems and cellular compartments. Revisiting how BMPR2 functions throughout health and disease in cells and organs beyond the lung vasculature may provide insight into the contribution of these organ systems to PAH pathogenesis as well as the potential systemic manifestation of PAH. Here we review our knowledge of the consequences of BMPR2 deficiency across multiple organ systems.

Genetic variability in equine GDF9 and BMP15 genes in Arabian and Thoroughbred mares

In horses, multiple ovulation resulting in implantation of multiple embryos is adverse. However, understanding the mechanisms underlying initiation of multiple ovulation (MO) is advantageous and is related to an increase in efficiency of embryo transfer techniques. It has been postulated that MO may have a genetic background. Two major genes: bone morphogenetic protein 15 (BMP15) and growth and differentiation factor 9 (GDF9) are considered to play a crucial role in folliculogenesis and controlling the ovulation rate. Thus, the aim of the presented study was to identify the variation within equine BMP15 and GDF9 genes to verify their potential role on spontaneous, repetitive multiple ovulations in mares. In addition, variation screening of investigated genes in population of Thoroughbred and Arabian breeds was performed together with establishment of transcript abundance of BMP15 and GDF9 genes in equine ovarian tissue. Sanger sequencing of Arabian and Thoroughbred mares divided according to ovulation rate, revealed occurrence of 3 SNPs in BMP15 and STS in GDF9 genes. The PCR-RLFP and statistical analysis indicated that none of the genotype frequencies were significant in any breeds and none of them were claimed as functional according to ovulation rate. Furthermore, evaluation of transcript abundance by RT -PCR of both genes in ovarian tissues showed that expression of both genes was similar but GDF9 was significantly expressed in growing follicles with 21-30 mm diameter and in ovarian parenchyma, which suggest their potential role in folliculogenesis.

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.

Age-related expression of TGF beta family receptors in human cumulus oophorus cells

PURPOSE

During ovarian follicle growth, local cellular interactions are essential for oocyte quality acquisition and successful fertilization. While cumulus cells (CCs) nurture oocytes, they also deliver oocyte-secreted factors (OSFs) that activate receptors on CCs. We hypothesized that disturbance of those interactions contributes to age-related lower reproductive success in women submitted to assisted reproductive technology treatments.

METHODS

Women aged 27-48, without recognized personal reproductive disorder, were enrolled in the study and divided in <35- and ≥35-year-old groups. CCs collected upon follicle aspiration were processed for immunocytochemistry and RNA extraction. The expression patterns of OSF receptors BMPR2, ALK 4, ALK5, and activin receptor-like kinase (ALK6) were studied.

RESULTS

Independently of age, receptors were found mostly in the cell periphery. The quantitative assay revealed that in older women, BMPR2, ALK 4, and ALK6 were all significantly decreased, whereas ALK5 was slightly increased.

CONCLUSIONS

Female age imparts an effect on the expression of OSF receptors in CCs. The findings indicate that reproductive aging affects the local regulation of signaling pathways mediated by BMPR2, ALK6, and ALK4 receptor activation, suggesting their joint involvement.

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.

Relationship between the concentration of bone morphogenetic protein-15 (BMP-15) and growth differentiation factor-9 (GDF-9) in pre-ovulatory follicles, ovarian cysts and serum in sows

The aim of the study was to compare and assess the relationship between peripheral and ovarian bone morphogenetic protein-15 (BMP-15) and growth differentiation factor-9 (GDF-9) concentration in cysts-bearing and non-cysts-bearing sows. The research involved multiparous sows (cysts-bearing sows, n = 20; non-cysts-bearing sows, n = 26). Serum, cystic follicular fluid or fluid from the ovulatory follicles was collected from each of the sows at the time of the slaughter. The collected serum and cystic/follicular fluid samples were tested for BMP-15 and GDF-9 concentrations. BMP-15 and GDF-9 concentrations in fluid from ovarian cysts were significantly higher than in the follicular fluid (P < 0.01). The concentration of BMP-15 and GDF-9 in the serum of sows with cysts was also higher than in ovulating sows (P < 0.05 and P < 0.01, respectively). The concentration of BMP-15 in serum was positively correlated with the concentration of said protein in pre-ovulatory follicles and cysts (r = 0.70; P < 0.01 and r = 0.50; P < 0.05, respectively). A positive correlation was also found between the concentration of serum GDF-9 and cyst GDF-9 (r = 0.55; P < 0.05). Moreover, another positive correlation was detected between the BMP-15 and GDF-9 concentrations, with the highest correlation coefficient recorded in the cyst fluid (r = 0.87; P < 0.01). This study for the first time demonstrates the presence of BMP-15 and GDF-9 in the cyst fluid in sows and determines a positive correlation between the concentration of the above factors in the follicular/cystic fluid and serum. Therefore, it is possible that the determination of BMP-15 and GDF-9 serum concentration may assist diagnosing ovarian cysts in sows. However, it is suggested that further studies involving a more in-depth analysis of the role of BMP-15 and GDF-9 in the pathogenesis of ovarian cysts in pigs are needed.

Association between BMP15 Gene Polymorphism and Reproduction Traits and Its Tissues Expression Characteristics in Chicken

BMP15 (Bone morphogenetic protein 15) is an oocyte-secreted growth factor required for ovarian follicle development and ovulation in mammals, but its effects on reproduction in chickens are unclear. In this study, the association between BMP15 polymorphisms and reproduction traits were analyzed, and its expression characteristics in different tissues were explored in LaiWu Black chickens. Three single nucleotide polymorphisms (SNPs) were identified in four hundred LaiWu Black chickens. One SNP (NC_006091.3:g.1773T>C) located in exon 2 which was significantly associated with egg weight at first egg (EWFE) (P = 0.0389), was novel. Diplotypes based on the three SNPs were found to be significantly associated with egg weight at age of 43W (EW43) (P = 0.0058). The chickens with H3H3 diplotype had their first egg 0.57 days later than chickens with H5H5 diplotype and 1.21 days-3.96 days earlier than the other five diplotype chickens. The egg production at age of 43W (E43), egg production at age of 46W (E46) and egg production at age of 48W (E48) for chickens with H3H3 diplotype were the highest among all the chickens, and the E48 of chickens with H3H3 diplotype had 11.83 eggs higher than chickens with H1H5 diplotype. RT-qPCR results showed that the expression level of BMP15 gene in ovarian follicle was in the order of 4 mm>6 mm -8 mm> 15 mm -19 mm> 23 mm -29 mm > 33 mm -34 mm in diameter. The mRNA level in follicles of 4 mm and 6-8 mm in diameter were significantly higher than that in the other follicles (P<0.01). In the same week, the highest mRNA level was found in the ovary, and it was significantly different from that found in the liver and oviduct (P<0.01). Our results indicate that BMP15 plays a vital role in the development of ovary and follicles, especially in the development of primary follicles. H3H3 may be an potential advantageous molecular marker for improving reproduction traits in chickens.

GDF9 is transiently expressed in oocytes before follicle formation in the human fetal ovary and is regulated by a novel NOBOX transcript

During human fetal ovary development, the process of primordial follicle formation is immediately preceded by a highly dynamic period of germ cell and somatic cell reorganisation. This is regulated by germ-cell specific transcription regulators, by the conserved RNA binding proteins DAZL and BOLL and by secreted growth factors of the TGFβ family, including activin βA: these all show changing patterns of expression preceding follicle formation. In mice, the transcription factor Nobox is essential for follicle formation and oocyte survival, and NOBOX regulates the expression of GDF9 in humans. We have therefore characterised the expression of GDF9 in relation to these known key factors during follicle formation in the human fetal ovary. mRNA levels of GDF9, BMP15 and NOBOX were quantified by qRT-PCR and showed dramatic increases across gestation. GDF9 protein expression was localised by immunohistochemistry to the same population of germ cells as those expressing activin βA prior to follicle formation but did not co-localise with either BOLL or DAZL. A novel NOBOX isoform was identified in fetal ovary that was shown to be capable of up-regulating the GDF9 promoter in reporter assays. Thus, during oogenesis in humans, oocytes go through a dynamic and very sharply demarcated sequence of changes in expression of these various proteins, even within individual germ cell nests, likely to be of major functional significance in determining selective germ cell survival at this key stage in ovarian development. Transcriptional variation may contribute to the range of age of onset of POI in women with NOBOX mutations.

Maternal Low-protein Diet Alters Ovarian Expression of Folliculogenic and Steroidogenic Genes and Their Regulatory MicroRNAs in Neonatal Piglets

Maternal malnutrition during pregnancy may give rise to female offspring with disrupted ovary functions in adult age. Neonatal ovary development predisposes adult ovary function, yet the effect of maternal nutrition on the neonatal ovary has not been described. Therefore, here we show the impact of maternal protein restriction on the expression of folliculogenic and steroidogenic genes, their regulatory microRNAs and promoter DNA methylation in the ovary of neonatal piglets. Sows were fed either standard-protein (SP, 15% crude protein) or low-protein (LP, 7.5% crude protein) diets throughout gestation. Female piglets born to LP sows showed significantly decreased ovary weight relative to body weight (p<0.05) at birth, which was accompanied with an increased serum estradiol level (p<0.05). The LP piglets demonstrated higher ratio of bcl-2 associated X protein/B cell lymphoma/leukemia-2 mRNA (p<0.01), which was associated with up-regulated mRNA expression of bone morphogenic protein 4 (BMP4) (p<0.05) and proliferating cell nuclear antigen (PCNA) (p<0.05). The steroidogenic gene, cytochrome P450 aromatase (CYP19A1) was significantly down-regulated (p<0.05) in LP piglets. The alterations in ovarian gene expression were associated with a significant down-regulation of follicle-stimulating hormone receptor mRNA expression (p<0.05) in LP piglets. Moreover, three microRNAs, including miR-423-5p targeting both CYP19A1 and PCNA, miR-378 targeting CYP19A1 and miR-210 targeting BMP4, were significantly down-regulated (p<0.05) in the ovary of LP piglets. These results suggest that microRNAs are involved in mediating the effect of maternal protein restriction on ovarian function through regulating the expression of folliculogenic and steroidogenic genes in newborn piglets.

Follicular dynamics and gene expression in granulosa cells, corpora lutea and oocytes from gilts of breeds with low and high ovulation rates

Follicular dynamics and the expression of candidate genes using real-time polymerase chain reaction (PCR) were compared during the oestrous cycle of pig breeds with high (commercial line; n = 24) and low (local Brazilian Piau; n = 21) ovulation rates and prolificacy. Gilts were killed on Days 0, 4, 10 and 18 of the oestrous cycle and visible ovarian follicles were classified by follicular diameter. Recovered cumulus–oocyte complexes were classified as normal or atretic and frozen in liquid nitrogen until RNA extraction. Low ovulation rates and/or prolificacy in Piau gilts was associated with a different pattern of follicle development, with lower numbers of small follicles on Day 18, fewer large follicles on Days 0 and 18 (P ≤ 0.05) and a higher proportion of atretic follicles on Days 0 and 18 (P ≤ 0.05). Compared with commercial line gilts, less-prolific Piau gilts exhibited higher expression of apoptotic genes during luteolysis (CASP3 and FASL; P ≤ 0.05), decreased expression of TGFBR2 and BAX mRNA in the corpus luteum (P ≤ 0.05), higher expression of apoptotic genes (FAS, BCL2 and CASP8; P ≤ 0.05) in granulosa cells and a greater abundance (P ≤ 0.05) of genes controlling oocyte-secreted factors (GDF9, BMP15 and BMP6), suggesting underlying mechanisms controlling differences in follicular development, ovulation rate and inherent prolificacy in this pig breed.

Anti-Müllerian hormone (AMH), inhibin-α, growth differentiation factor 9 (GDF9), and bone morphogenic protein-15 (BMP15) mRNA and protein are influenced by photoperiod-induced ovarian regression and recrudescence in Siberian hamster ovaries

Exposure of Siberian hamsters to short photoperiod (SD) inhibits ovarian function, including folliculogenesis, whereas function is restored with their transfer to long photoperiods (LD). To investigate the mechanism of photo-stimulated recrudescence, we assessed key folliculogenic factors-anti-Müllerian hormone (AMH), inhibin-α, growth differentiation factor-9 (GDF9), and bone morphogenic protein-15 (BMP15)-across the estrus cycle and in photo-regressed and recrudescing ovaries. Adult hamsters were exposed to either LD or SD for 14 weeks, which respectively represent functional and regressed ovaries. Select regressed hamsters were transferred back to LD for 2 (post-transfer week 2; PTw2) or 8 weeks (PTw8). Ovaries were collected and fixed in formalin for immunohistochemistry or frozen in liquid nitrogen for real-time PCR. AMH, inhibin-α, GDF9, and BMP15 mRNA and protein were detected in all stages of the estrus cycle. Fourteen weeks of SD exposure increased (P < 0.05) ovarian AMH, GDF9, and BMP15, but not inhibin-α mRNA levels as compared to LD. Transfer of regressed hamsters to stimulatory long photoperiod for 8 weeks returned AMH and GDF9 mRNA levels to LD-treated levels, and further increased mRNA levels for inhibin-α and BMP15. Immunostaining for AMH, inhibin-α, GDF9, and BMP15 proteins was most intense in preantral/antral follicles and oocytes. The overall immunostaining extent for AMH and inhibin-α generally mirrored the mRNA data, though no changes were observed for GDF9 or BMP15 immunostaining. Shifts in mRNA and protein levels across photoperiod conditions suggest possible syncretic roles for these folliculogenic factors in photo-stimulated recrudescence via potential regulation of follicle recruitment, preservation, and development.

Short-term culture of ovarian cortical strips from capuchin monkeys (Sapajus apella): a morphological, viability, and molecular study of preantral follicular development in vitro

The aim of this study was to evaluate whether an in vitro culture (IVC) medium containing either or not β-mercaptoethanol (BME), bone morphogenetic protein 4 (BMP4), or pregnant mare serum gonadotrophin (PMSG) could be able to promote the development of capuchin monkeys' preantral follicles enclosed in ovarian cortical strips. Follicular viability after IVC was similar to control (89.32%). Primordial follicle recruitment to primary stage was not reached with IVC, but the rate of secondary follicle formation was increased in the medium supplemented with BME, BMP4, and PMSG (44.86%) when compared to IVC control (9.20%). In the medium supplemented with BME, BMP4, and PMSG, contrary to other media, anti-müllerian hormone-messenger RNA (mRNA) expression in ovarian tissue was upregulated (3.4-fold), while that of growth differentiation factor-9 was maintained. The BMP4-mRNA expression, however, appeared downregulated in all cultured tissues. Our findings show a favorable effect of BME, BMP4, and PMSG on the in vitro development of secondary follicles from capuchin monkeys.

Single-cell expression analysis of BMP15 and GDF9 in mature oocytes and BMPR2 in cumulus cells of women with polycystic ovary syndrome undergoing controlled ovarian hyperstimulation

PURPOSE

To detect expression of bone morphogenetic protein 15 (BMP15) and growth differentiation factor 9 (GDF9) in oocytes, and their receptor type 2 receptor for BMPs (BMPR2) in cumulus cells in women with polycystic ovary syndrome (PCOS) undergoing in vitro fertilization (IVF), and determine if BMPR2, BMP15, and GDF9 expression correlate with hyperandrogenism in FF of PCOS patients.

METHODS

Prospective case-control study. Eighteen MII-oocytes and their respective cumulus cells were obtained from 18 patients with PCOS, and 48 MII-oocytes and cumulus cells (CCs) from 35 controls, both subjected to controlled ovarian hyperstimulation (COH), and follicular fluid (FF) was collected from small (10-14 mm) and large (>18 mm) follicles. RNeasy Micro Kit (Qiagen) was used for RNA extraction and gene expression was quantified in each oocyte individually and in microdissected cumulus cells from cumulus-oocyte complexes retrieved from preovulatory follicles using qRT-PCR. Chemiluminescence and RIA assays were used for hormone assays.

RESULTS

BMP15 and GDF9 expression per oocyte was higher among women with PCOS than the control group. A positive correlation was found between BMPR2 transcripts and hyperandrogenism in FF of PCOS patients. Progesterone values in FF were lower in the PCOS group.

CONCLUSION

We inferred that BMP15 and GDF9 transcript levels increase in mature PCOS oocytes after COH, and might inhibit the progesterone secretion by follicular cells in PCOS follicles, preventing premature luteinization in cumulus cells. BMPR2 expression in PCOS cumulus cells might be regulated by androgens.

Characterization of bmp15 and its regulation by human chorionic gonadotropin in the follicle of gibel carp (Carassius auratus gibelio)

Bone morphogenetic protein (BMP15) is a member of the transforming growth factor β (TGF-β) superfamily with a key role in regulating follicle development in mammals and birds. However, potential ovarian roles of BMPs remain unexplored in teleosts. In this study, the full-length sequences of bmp15 were obtained using rapid-amplification of cDNA ends (RACE). The full-length cDNA sequence of bmp15 is 2217 bp which contained 214 bp 5'-UTR and 845 bp 3'-UTR. The open reading frame (ORF) sequence of bmp15 is 1158 bp, encoding a predicted protein of 385 amino acid residues. BMP15 has a specific RXXR protease cleavage site of TGF-β superfamily (is RIRR) and six conserved cysteine residues. Using real-time quantitative PCR revealed that bmp15 mRNA was largely expressed in the ovary and testis and mostly in oocytes within the follicle, slightly expressed in muscle, liver and pituitary. BMP15 is mainly present at stage I follicles by real-time quantitative PCR and immunohistochemistry. Phylogenetic analysis showed that gibel carp bmp15 was similar to bmp15 of zebrafish and other fish species. Treatment with human chorionic gonadotropin (hCG) in isolated follicles of gibel carp in vitro showed altered bmp15 mRNA expression: when treated with 10 ng/mL hCG for 10h, the expression level of bmp15 was significantly increased. However, with proceeding cultivation, the expression level of BMP15 mRNA decreased. The results of this study indicate that bmp15 may play a key role during development of follicles in gibel carp, especially in early stage follicles.

[Progress in exploring genes for high fertility in ewes]

Fecundity trait in sheep is regulated by some major genes. Among them, BMPR-IB, BMP-15, and GDF-9 are most distinguishing. The mutant FecB of BMPR-IB has multiplicative effects on ovulation. GDF-9's mutants FecGH, FecI, and BMP-15's mutants FecXI, FecXH, FecXG, FecXB, FecXL, and FecXR increase ovulation rate in the heterozygote but result in sterile phenotypes in the homozygote, while GDF-9's mutant, FecGE, only increases ovulation rate in the homozygote. In addition, Woodlands and Lacaune are known as inheritable major genes. Woodlands gene is an X-linked maternally imprinted gene, and Lacaune is similar to FecB with a multiplicative effect on ovulation rate. The size of the effect of one copy of a mutation on ovulation rate ranges from an extra 0.4 ovulations for the woodlands mutation to an extra 1.5 ovulations for the BMPR-IB and Lacaune mutation. Investigation into these genes will not only help to select breeds with high fertility, but also give a chance to further elucidate the mechanism involved in the phenomenon. This review summaries the source, location, phenotype, and mechanism of the major genes in all breeds of sheep.

Oocytes in sheep homozygous for a mutation in bone morphogenetic protein receptor 1B express lower mRNA levels of bone morphogenetic protein 15 but not growth differentiation factor 9

The aim of this study was to test the hypothesis that the high ovulation rate in ewes (BB) homozygous for a mutation in the bone morphogenetic protein receptor type 1B (BMPR1B) gene is linked to lower BMP15 and/or GDF9 mRNA in oocytes compared with those in wild-type (++) ewes. Cumulus cell-oocyte complexes (COC) and granulosa cells (GC) were recovered from ≥1 mm diameter follicles of BB and ++ ewes during a prostaglandin-induced follicular phase. Expression levels of GDF9 and BMP15 were measured by multiplex qPCR from individual COC. The gonadotropin-induced cAMP responses of the GC from each non-atretic follicle were measured following treatment with FSH or human chorionic gonadotropin. In a separate validation experiment, GDF9 and BMP15 expression was present only in oocytes and not in cumulus cells. There was no effect of follicular diameter on oocyte-derived GDF9 or BMP15 mRNA levels. The mean expression levels of BMP15, but not GDF9, were significantly lower in all non-atretic follicles, including the subsets containing either FSH- or LH-responsive GC in BB, compared with ++, ewes. No genotype effects were noted for FSH-induced cAMP production by GC either with respect to dose of, or number of follicles responding to, FSH. However, ovaries from BB ewes contained significantly more follicles responsive to LH, with respect to cAMP production in GC. We propose that these findings are consistent with the hypothesis that the higher ovulation rate in BB sheep is due, at least in part, to lower oocyte-derived BMP15 mRNA levels together with the earlier onset of LH-responsiveness in GC.