The fundamental role of bone morphogenetic protein 15 in ovarian function and its involvement in female fertility disorders

Understanding the Mechanisms of Diminished Ovarian Reserve: Insights from Genetic Variants and Regulatory Factors

Delaying childbearing age has become a trend in modern times, but it has also led to a common challenge in clinical reproductive medicine-diminished ovarian reserve (DOR). Since the mechanism behind DOR is unknown and its clinical features are complex, physicians find it difficult to provide targeted treatment. Many factors affect ovarian reserve function, and existing studies have shown that genetic variants, upstream regulatory genes, and changes in protein expression levels are present in populations with reduced ovarian reserve function. However, existing therapeutic regimens often do not target the genetic profile for more individualized treatment. In this paper, we review the types of genetic variants, mutations, altered expression levels of microRNAs, and other related factors and their effects on the regulation of follicular development, as well as altered DNA methylation. We hope this review will have significant implications for the future treatment of individuals with reduced ovarian reserve.

Prenatal acetaminophen exposure and the developing ovary: Time, dose, and course consequences for fetal mice

Acetaminophen is an emerging endocrine disrupting chemical and has been detected in various natural matrices. Numerous studies have documented developmental toxicity associated with prenatal acetaminophen exposure (PAcE). In this study, we established a PAcE Kunming mouse model at different time (middle pregnancy and third trimester), doses (low, middle, high) and courses (single or multi-) to systematically investigate their effects on fetal ovarian development. The findings indicated PAcE affected ovarian development, reduced fetal ovarian oocyte number and inhibited cell proliferation. A reduction in mRNA expression was observed for genes associated with oocyte markers (NOBOX and Figlα), follicular development markers (BMP15 and GDF9), and pre-granulosa cell steroid synthase (SF1 and StAR). Notably, exposure in middle pregnancy, high dose, multi-course resulted in the most pronounced inhibition of oocyte development; exposure in third trimester, high dose and multi-course led to the most pronounced inhibition of follicular development; and in third trimester, low dose and single course, the inhibition of pre-granulosa cell function was most pronounced. Mechanistic investigations revealed that PAcE had the most pronounced suppression of the ovarian Notch signaling pathway. Overall, PAcE caused fetal ovarian multicellular toxicity and inhibited follicular development with time, dose and course differences.

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.

A temporal extracellular transcriptome atlas of human pre-implantation development

Non-invasively evaluating gene expression products in human pre-implantation embryos remains a significant challenge. Here, we develop a non-invasive method for comprehensive characterization of the extracellular RNAs (exRNAs) in a single droplet of spent media that was used to culture human in vitro fertilization embryos. We generate the temporal extracellular transcriptome atlas (TETA) of human pre-implantation development. TETA consists of 245 exRNA sequencing datasets for five developmental stages. These data reveal approximately 4,000 exRNAs at each stage. The exRNAs of the developmentally arrested embryos are enriched with the genes involved in negative regulation of the cell cycle, revealing an exRNA signature of developmental arrest. Furthermore, a machine-learning model can approximate the morphology-based rating of embryo quality based on the exRNA levels. These data reveal the widespread presence of coding gene-derived exRNAs at every stage of human pre-implantation development, and these exRNAs provide rich information on the physiology of the embryo.

Growth factors and female reproduction in vertebrates

Female reproductive efficiency is influenced by the outcomes of various processes, including folliculogenesis, apoptosis, response to gonadotropin signaling, oocyte maturation, and ovulation. The role of hormones in regulating these processes and other reproductive activities has been well established. It is becoming increasingly evident that in addition to well-characterized hormones, growth factors play vital roles in regulating some of these reproductive activities. Growth factors and their receptors are widely distributed in vertebrate ovaries at different stages of ovarian development, indicating their involvement in intraovarian reproductive functions. In the ovary, cell surface receptors allow growth factors to regulate intraovarian reproductive activities. Understanding these actions in the reproductive axis would provide a tool to target growth factors and/or their receptors to yield desirable reproductive outcomes. These include enrichment of in vitro maturation and fertilization culture media, and management of infertility. This review discusses some widely characterized growth factors belonging to the TGF, EGF, IGF, FGF, and BDNF family of peptides and their role in female reproduction in vertebrates, with a focus on mammals.

Essential Role of Granulosa Cell Glucose and Lipid Metabolism on Oocytes and the Potential Metabolic Imbalance in Polycystic Ovary Syndrome

Granulosa cells are crucial for the establishment and maintenance of bidirectional communication among oocytes. Various intercellular material exchange modes, including paracrine and gap junction, are used between them to achieve the efficient delivery of granulosa cell structural components, energy substrates, and signaling molecules to oocytes. Glucose metabolism and lipid metabolism are two basic energy metabolism pathways in granulosa cells; these are involved in the normal development of oocytes. Pyruvate, produced by granulosa cell glycolysis, is an important energy substrate for oocyte development. Granulosa cells regulate changes in intrafollicular hormone levels through the processing of steroid hormones to control the development process of oocytes. This article reviews the material exchange between oocytes and granulosa cells and expounds the significance of granulosa cells in the development of oocytes through both glucose metabolism and lipid metabolism. In addition, we discuss the effects of glucose and lipid metabolism on oocytes under pathological conditions and explore its relationship to polycystic ovary syndrome (PCOS). A series of changes were found in the endogenous molecules and ncRNAs that are related to glucose and lipid metabolism in granulosa cells under PCOS conditions. These findings provide a new therapeutic target for patients with PCOS; additionally, there is potential for improving the fertility of patients with PCOS and the clinical outcomes of assisted reproduction.

Optimisation of hormonal treatment to improve follicular development in one-day-old mice ovaries cultured under in vitro condition

CONTEXT

Base medium containing knock-out serum replacement (KSR) has been found to support formation and maintenance of follicles in one-day-old mice ovaries, but has not been shown to properly support activation and growth of primordial follicles.

AIMS

The present study was conducted to tailor the hormonal content of base medium containing KSR to enhance development of primordial follicles in neonatal ovaries.

METHODS

One-day-old mice ovaries were initially cultured with base medium for four days, and then, different hormonal treatments were added to the culture media and the culture was proceeded for four additional days until day eight. Ovaries were collected for histological and molecular assessments on days four and eight.

KEY RESULTS

In experiment I, the main and interactive effects of FSH and testosterone were investigated and FSH promoted activation of primordial follicles and development of primary and preantral follicles, and upregulated genes of phosphoinositide 3-kinase (Pi3k ), KIT ligand (Kitl ), growth differentiation factor 9 (Gdf9 ) and follicle stimulating hormone receptor (Fshr ) (P Bmp15 ), Connexin-43 (Cx43 ) and luteinising hormone and choriogonadotropin receptor (Lhcgr ) (P P Lhcgr (P P >0.05).

CONCLUSIONS

Supplementation of culture medium containing KSR with gonadotropins, particularly hMG, could improve follicular growth and expression of factors regulating follicular development.

IMPLICATIONS

This study was a step forward in formulating an optimal medium for development of follicles in cultured one-day-old mice ovaries.

Rescue of bmp15 deficiency in zebrafish by mutation of inha reveals mechanisms of BMP15 regulation of folliculogenesis

As an oocyte-specific growth factor, bone morphogenetic protein 15 (BMP15) plays a critical role in controlling folliculogenesis. However, the mechanism of BMP15 action remains elusive. Using zebrafish as the model, we created a bmp15 mutant using CRISPR/Cas9 and demonstrated that bmp15 deficiency caused a significant delay in follicle activation and puberty onset followed by a complete arrest of follicle development at previtellogenic (PV) stage without yolk accumulation. The mutant females eventually underwent female-to-male sex reversal to become functional males, which was accompanied by a series of changes in secondary sexual characteristics. Interestingly, the blockade of folliculogenesis and sex reversal in bmp15 mutant could be partially rescued by the loss of inhibin (inha-/-). The follicles of double mutant (bmp15-/-;inha-/-) could progress to mid-vitellogenic (MV) stage with yolk accumulation and the fish maintained their femaleness without sex reversal. Transcriptome analysis revealed up-regulation of pathways related to TGF-β signaling and endocytosis in the double mutant follicles. Interestingly, the expression of inhibin/activin βAa subunit (inhbaa) increased significantly in the double mutant ovary. Further knockout of inhbaa in the triple mutant (bmp15-/-;inha-/-;inhbaa-/-) resulted in the loss of yolk granules again. The serum levels of estradiol (E2) and vitellogenin (Vtg) both decreased significantly in bmp15 single mutant females (bmp15-/-), returned to normal in the double mutant (bmp15-/-;inha-/-), but reduced again significantly in the triple mutant (bmp15-/-;inha-/-;inhbaa-/-). E2 treatment could rescue the arrested follicles in bmp15-/-, and fadrozole (a nonsteroidal aromatase inhibitor) treatment blocked yolk accumulation in bmp15-/-;inha-/- fish. The loss of inhbaa also caused a reduction of Vtg receptor-like molecules (e.g., lrp1ab and lrp2a). In summary, the present study provided comprehensive genetic evidence that Bmp15 acts together with the activin-inhibin system in the follicle to control E2 production from the follicle, Vtg biosynthesis in the liver and its uptake by the developing oocytes.

Effects of obesity on the serum BMP15, GDF9, and kisspeptin concentrations in women of reproductive age

Background

As BMP15, GDF9, and kisspeptin all play critical roles in folliculogenesis and fertilization, investigating the possible relationship between obesity and these three factors could prove crucial in relation to understanding the role of obesity in infertility. Thus, the present study sought to determine the effects of obesity on the serum BMP15, GDF9, and kisspeptin concentrations in women of reproductive age.

Methods

Ninety female participants were equally divided into three groups: class-1 obese (n=30), class-2 obese (n=30), and normal weight (control; n=30). The participants' serum BMP15, GDF9, and AMH concentrations were measured. Moreover, the serum kisspeptin concentrations were evaluated in the class-1 obese and control groups by means of the enzyme-linked immunosorbent assay (ELISA) method while the participants were in their menstrual period.

Results

The serum BMP15 and kisspeptin concentrations were found to be much higher in the control group than in both obese groups (p=0.001 and p=0.01, respectively). While the GDF9 concentration exhibited a statistically significant positive correlation with age, the BMP15 concentration exhibited a positive correlation with the kisspeptin and LH concentrations in the control group. In addition, a positive correlation was identified between the BMP15 concentration and both age and the glucose level and a negative correlation with the insulin level in both the obese groups.

Conclusions

Obesity appears to reduce the serum BMP15 and kisspeptin concentrations in obese women of reproductive age. This reduction may represent a milestone in reproductive dysfunction and may be used to predict the success of infertility treatment in obese women.

Current understanding of the genomic abnormities in premature ovarian failure: chance for early diagnosis and management

Premature ovarian failure (POF) is an insidious cause of female infertility and a devastating condition for women. POF also has a strong familial and heterogeneous genetic background. Management of POF is complicated by the variable etiology and presentation, which are generally characterized by abnormal hormone levels, gene instability and ovarian dysgenesis. To date, abnormal regulation associated with POF has been found in a small number of genes, including autosomal and sex chromosomal genes in folliculogenesis, granulosa cells, and oocytes. Due to the complex genomic contributions, ascertaining the exact causative mechanisms has been challenging in POF, and many pathogenic genomic characteristics have yet to be elucidated. However, emerging research has provided new insights into genomic variation in POF as well as novel etiological factors, pathogenic mechanisms and therapeutic intervention approaches. Meanwhile, scattered studies of transcriptional regulation revealed that ovarian cell function also depends on specific biomarker gene expression, which can influence protein activities, thus causing POF. In this review, we summarized the latest research and issues related to the genomic basis for POF and focused on insights gained from their biological effects and pathogenic mechanisms in POF. The present integrated studies of genomic variants, gene expression and related protein abnormalities were structured to establish the role of etiological genes associated with POF. In addition, we describe the design of some ongoing clinical trials that may suggest safe, feasible and effective approaches to improve the diagnosis and therapy of POF, such as Filgrastim, goserelin, resveratrol, natural plant antitoxin, Kuntai capsule et al. Understanding the candidate genomic characteristics in POF is beneficial for the early diagnosis of POF and provides appropriate methods for prevention and drug treatment. Additional efforts to clarify the POF genetic background are necessary and are beneficial for researchers and clinicians regarding genetic counseling and clinical practice. Taken together, recent genomic explorations have shown great potential to elucidate POF management in women and are stepping from the bench to the bedside.

Melatonin effective to reduce the microscopic symptoms of polycystic ovary syndrome-related infertility: An experimental study

Polycystic ovary syndrome (PCOS) is an endocrine disorder seen in women of reproductive age and has been gradually increasing over the years. The mechanism of the syndrome has still not been clearly understood. In this study, the possible effects of exogenously administrated melatonin on melatonin (MT1) receptor, Growth Differentiation Factor-9 (GDF9), and Bone Morphogenetic Protein-15 (BMP15) in experimental PCOS were investigated. Thirty-two 6-8-week-old Sprague-Dawley rats were randomly divided into four groups (n = 8 in each) as Sham control (Group 1), Melatonin (Group 2), PCOS (Group 3), and PCOS + Melatonin (Group 4) groups. At the end of the 21st day, the experiment was terminated, the ovary tissues were taken, and Hematoxylin-Eosin staining, MT1, GDF9, BMP15 immunohistochemical labeling, western blot, and quantitative real-time polymerase chain reaction (qPCR) analyses were performed. Serum Luteinizing Hormone (LH)/Follicle Stimulating Hormone (FSH) levels and colpo-cytological examinations were also carried out. The results revealed that melatonin administration increased the expression levels of the MT1 receptor, GDF9, and BMP15 in PCOS at protein and mRNA levels. It was determined that melatonin administration reduced the microscopic symptoms of PCOS. Melatonin was found to be effective via the MT1 receptor in the pathogenesis of PCOS, and it suppressed the transport pathways of GDF9 to granulosa cells in antral follicles.

Decreased GDF9 and BMP15 in follicle fluid and granulosa cells and outcomes of IVF-ET among young patients with low prognosis

PURPOSE

To analyze the level of growth differentiation factor 9 (GDF9) and bone morphogenetic protein 15 (BMP15) in follicle fluid (FF) and granulosa cells (GCs) derived from young patients with low prognosis for in vitro fertilization and embryo transfer (IVF-ET) treatment.

METHODS

A prospective cohort study was carried out by enrolling 52 young patients with low prognosis according to the POSEIDON classification group 3 (low prognosis group) and 51 young patients with normal ovarian reserve (control group). The concentration of the GDF9 and BMP15 proteins in FF was determined by enzyme-linked immunosorbent assay. The mRNA level of the GDF9 and BMP15 in the GCs was measured by quantitative real-time PCR.

RESULTS

The concentration of GDF9 (1026.72 ± 159.12 pg/mL vs. 1298.06 ± 185.41 pg/mL) and BMP15 (685.23 ± 143.91 pg/mL vs. 794.37 ± 81.79 pg/mL) in FF and the mRNA level of GDF9 and BMP15 in the GCs and the live birth rate per treatment cycle started (30.77% vs. 50.98%) and oocytes retrieved (4.25 ± 1.91 vs.12.04 ± 4.24) were significantly lower, whereas the canceled cycle rate was significantly higher (9.62% vs. 0) in the low prognosis group compared with the control group (P < 0.05). The expression of GDF9 and BMP15 in the ovary was positively correlated with live birth (P < 0.05).

CONCLUSION

The expression of GDF9 and BMP15 in the ovary was decreased in young patients with low prognosis accompanied by a poorer outcome of IVF-ET treatment.

TRIAL REGISTRATION

ChiCTR1800016107 (Chinese Clinical Trial Registry), May 11, 2018. ( http://www.chictr.org.cn/edit.aspx?pid=27216&htm=4 ).

Network and experimental pharmacology on mechanism of Si-Wu-tang improving ovarian function in a mouse model of premature ovarian failure induced by cyclophosphamide

ETHNOPHARMACOLOGICAL RELEVANCE

Si-Wu-Tang (SWT) has become a common basic prescription for supplementing blood and regulating menstruation, and enjoys the reputation of "the first prescription in gynecology". It is often reported in the treatment of premature ovarian failure (POF). However, knowledge of its specific mechanism is still limited.

AIM OF THE STUDY

This study aimed to identify the potential effects and underlying mechanisms of SWT on POF.

MATERIALS AND METHODS

After confirming the therapeutic effect of SWT on POF mice induced by cyclophosphamide, we further clarified the promoting effect of SWT on ovarian follicle development by detecting the expression of key factors related to follicle development in the ovary in different ways.Then, network pharmacology and gene expression profiling of POF from the GEO database were used to clarify the underlying mechanisms. Molecular biology and molecular docking analysis were applied for final mechanism verification.

RESULTS

Our results showed that SWT increased body weight, ovarian index, reversed disordered serum hormone levels, and menstrual cycle in POF mice. After SWT treatment, the number of follicles at all levels in mice with POF also recovered. Using molecular biology techniques, it was proven that SWT can improve follicle development and angiogenesis in the microenvironment. The network pharmacology and gene expression profiling from the GEO database indicated that the PI3K/Akt signaling pathway may be the reason why SWT improves ovarian function in mice with POF. Subsequently, further Western blot and immunoprecipitation indicated that SWT indeed inhibited the PI3K/Akt signaling pathway in mice with POF. In addition, this conclusion was further confirmed by molecular docking experiments.

CONCLUSIONS

SWT can improve ovarian function in POF mice induced by cyclophosphamide, and its mechanism is related to the inhibition of the PI3K/Akt signaling pathway.

Oral Administration of Spirulina platensis at Early Gestation Modulates Litter Size and the Expression of Inhibin, Insulin, IGF-I, CO Q10, and BMP-15 in Ewes Induced for Twinning

Gestation in sheep necessitates the support of nutrients to avoid early embryonic mortalities. Therefore, this study investigates the effects of supplementing either L-arginine or Spirulina alga in the first trimester on the pregnancy rate, litter size, inhibin, insulin, IGF-I, CO Q10, and bone morphogenetic peptide 15 (BMP15) in maternal circulation. Animals were offered barley (500 g/head/day, 14% CP), alfalfa hay (1 kg/head/day, 12% CP), clean water, and balanced salt block licks as free choices. Forty Noemi and Najdi ewes were randomly allotted into three groups: control (C, n = 8), L-arginine (ARG, n = 16), and Spirulina (SP, n = 16). All females were implanted with CIDR for ten days. On days 8, 9, and 10, treated ewes were given a protocol comprised of human recombinant FSH at descending doses (50, 50, 40, 40, and 30, 30 IU, A.M, and P.M, respectively). At the fifth dose, animals were given an equivalent dose of hCG (240 IU). After CIDR withdrawal, ewes were exposed to fertile rams for mating. SP-ewes were orally given 50 ml (2%) Spirulina, and ARG-ewes were given 50 ml (35 mg/kg BW) L-arginine daily for 50 days postbreeding. Blood inhibin, insulin, IGF-I, CO Q10, and BMP15 were determined throughout gestation until parturition. The findings indicated that the conception rates were 25, 75, and 87.5% in C, ARG, and SP, respectively (P < 0.05). The percent of ewes giving birth to twins was 0, 25, and 50% in C, ARG, and SP, respectively (P < 0.05). The survival rates were 100, 81.8, and 83.3%, respectively. Birth weight was 5.6, 3.2, and 3.4 kg in C, ARG, and SP, respectively. Weaning weights were 28.3, 25.6, and 27.2 kg in C, ARG, and SP, respectively. BMP-15 was reduced (P < 0.05) in ARG than in C and SP. However, SP decreased (P < 0.05) inhibin more than in C and ARG. ARG and SP increased (P < 0.05) insulin than in C, whereas SP decreased (P < 0.05) IGF-I. SP increased CO Q10 compared with ARG. Ewes bearing twins revealed higher (P < 0.05) IGF-I (8.57 ng/ml) than those bearing singles (4.63 ng/ml); however, BMP-15 was higher in single (796.6 pg/ml) than in twin-bearing (387.5 pg/ml) ewes. In conclusion, providing early-gestating ewes with Spirulina enhances maternal health, productivity, and reproductive outcomes.

Effect of Lactobacillus plantarum on folliculogenesis in deep frying oil-fed rats

Today, the tendency towards Western World diet characterized by a high consumption of Deep Frying Oil (DFO), as well as female infertility has increased. On the other hand, probiotics are living microorganisms that can benefit human health. Therefore, this study aimed to investigate the effect of a probiotic treatment (Lactobacillus plantarum) on the process of follicular growth in rats fed with DFO. Twenty adult female Wistar rats were divided into four groups: control, DFO treatment, DFO treatment group receiving probiotic and the healthy group receiving probiotic for one month. After blood sampling and dissection, ovarian tissue was examined for the number of ovarian follicles at different stages. In addition, the expression of Bmp15 (Gdf-9b) and Gdf9 genes was assessed by the real-time PCR method. The ELISA test was also used to measure hormonal changes (LH and FSH). Data showed that rats treated with DFO had a significant decrease in follicle numbers, hormone levels and Bmp15 and Gdf9 gene expression. Moreover, the number of atretic follicles was increased. Treatment of rats with the probiotic reduced the observed side effects of DFO. Thus, treatments of rats with the probiotic mitigated some of the observed side effects of DFO. An increase in primordial follicles and a reduction of atretic follicles was indicated compared to the DFO group (P ≤ 0.001). Lactobacillus plantarum could reduce the detrimental effects of DFO on folliculogenesis through its beneficial effects.

Cooperative effects of oocytes and estrogen on the forkhead box L2 expression in mural granulosa cells in mice

Forkhead box L2 (FOXL2) plays a critical role in the development and function of mammalian ovaries. In fact, the causative effects of FOXL2 misregulations have been identified in many ovarian diseases, such as primary ovarian insufficiency and granulosa cell tumor; however, the mechanism by which FOXL2 expression is regulated is not well studied. Here, we showed that FOXL2 expression in ovarian mural granulosa cells (MGCs) requires stimulation by both oocyte-derived signals and estrogen in mice. In the absence of oocytes or estrogen, expression of FOXL2 and its transcriptional targets, Cyp19a1 and Fst mRNA, in MGCs were significantly decreased. Moreover, expression levels of Sox9 mRNA, but not SOX9 protein, were significantly increased in the FOXL2-reduced MGCs. FOXL2 expression in MGCs was maintained with either oocytes or recombinant proteins of oocyte-derived paracrine factors, BMP15 and GDF9, together with estrogen, and this oocyte effect was abrogated with an ALK5 inhibitor, SB431542. In addition, the FOXL2 level was significantly decreased in MGCs isolated from Bmp15^-/- /Gdf9^+/- mice. Therefore, oocyte, probably with estrogen, plays a critical role in the regulation of FOXL2 expression in mural granulosa cells in mice.

Oocyte-Secreted Serum Biomarkers GDF9 and BMP15 in Women with Endometriosis

Oocyte-secreted growth differentiation factor 9 (GDF9) and bone morphogenetic protein 15 (BMP15) are critical paracrine regulators of female fertility. Recent studies demonstrated that serum concentrations are associated with the number of oocytes retrieved during IVF, and therefore potential clinical use as biomarkers. However, it is unknown if the presence of endometriosis affects serum GDF9 or BMP15. An exploratory case–control study was prospectively performed on 60 women who underwent laparoscopy between April 2017 and August 2018 at two hospitals. GDF9 and BMP15 were measured by validated immunoassays in pre-operative serum samples. Data were analysed relative to laparoscopic assessment of endometriosis and staging. There were 35 women with confirmed laparoscopic diagnosis of endometriosis and 25 controls with no evidence of endometriosis at laparoscopy. GDF9 was detectable in 40% of controls and 48% of cases. There was no difference in median GDF9 concentrations between controls (20.0 pg/ml, range 20.0–2504 pg/ml) and cases (20.0 pg/ml, range 20.0–2963 pg/ml). BMP15 was detectable in 48% of controls and 58% of cases, with no difference in median concentrations between controls (26.5 pg/ml, range 24.0–1499 pg/ml) and cases (24.0 pg/ml, range 24.0–796 pg/ml). Furthermore, there were no significant differences in the proportion of detectable samples or concentrations of GDF9 or BMP15 with differing severities of endometriosis. In conclusion, serum concentrations of oocyte-secreted factors, GDF9 and BMP15 did not differ between control patients and patients with endometriosis. For clinical application in reproductive medicine, GDF9 and BMP15 serum biomarker quantitation is unlikely to be aberrant in the presence of endometriosis.

Chlorogenic acid improves functional potential of follicles in mouse whole ovarian tissues in vitro

BACKGROUND

Chlorogenic acid (CGA) is one of the well-known polyphenol compounds possessing several important biological and therapeutic functions. In order to optimize a culture system to achieve complete development of follicles, we focused on the effects of CGA supplementation during in vitro culture (IVC) on follicular development, oxidative stress, antioxidant capacity, developmental gene expression, and functional potential in cultured mouse ovarian tissue.

METHODS AND RESULTS

The collected whole murine ovaries were randomly divided into four groups: (1) non-cultured group (control 1) with 7-day-old mouse ovaries, (2) non-cultured group (control 2) with 14-day-old mouse ovaries, (3) cultured group (experimental 1) with the culture plates containing only the basic culture medium, (4) cultured group (experimental 2) with the culture plates containing basic culture medium + CGA (50, 100 and 200 µmol/L CGA). Afterward, histological evaluation, biochemical analyses, the expression assessment of genes related to follicular development and apoptosis as well as the analysis of 17-β-estradiol were performed. The results showed that supplementation of ovarian tissue with the basic culture media using CGA (100 µmol/l) significantly increased the survival, developmental and functional potential of follicles in whole mouse ovarian tissues after 7 days of culture. Furthermore, CGA (100 µmol/L) attenuated oxidative damage and enhanced the concentration of antioxidant capacity along with developmental gene expression.

CONCLUSION

It seems that supplementation of ovarian tissue with culture media using CGA could optimize follicular growth and development in the culture system.

Genetic landscape of a large cohort of Primary Ovarian Insufficiency: New genes and pathways and implications for personalized medicine

Background

Primary Ovarian Insufficiency (POI), a public health problem, affects 1-3.7% of women under 40 yielding infertility and a shorter lifespan. Most causes are unknown. Recently, genetic causes were identified, mostly in single families. We studied an unprecedented large cohort of POI to unravel its molecular pathophysiology.

Methods

375 patients with 70 families were studied using targeted (88 genes) or whole exome sequencing with pathogenic/likely-pathogenic variant selection. Mitomycin-induced chromosome breakages were studied in patients’ lymphocytes if necessary.

Findings

A high-yield of 29.3% supports a clinical genetic diagnosis of POI. In addition, we found strong evidence of pathogenicity for nine genes not previously related to a Mendelian phenotype or POI: ELAVL2, NLRP11, CENPE, SPATA33, CCDC150, CCDC185, including DNA repair genes: C17orf53(HROB), HELQ, SWI5 yielding high chromosomal fragility. We confirmed the causal role of BRCA2, FANCM, BNC1, ERCC6, MSH4, BMPR1A, BMPR1B, BMPR2, ESR2, CAV1, SPIDR, RCBTB1 and ATG7 previously reported in isolated patients/families. In 8.5% of cases, POI is the only symptom of a multi-organ genetic disease. New pathways were identified: NF-kB, post-translational regulation, and mitophagy (mitochondrial autophagy), providing future therapeutic targets. Three new genes have been shown to affect the age of natural menopause supporting a genetic link.

Interpretation

We have developed high-performance genetic diagnostic of POI, dissecting the molecular pathogenesis of POI and enabling personalized medicine to i) prevent/cure comorbidities for tumour/cancer susceptibility genes that could affect life-expectancy (37.4% of cases), or for genetically-revealed syndromic POI (8.5% of cases), ii) predict residual ovarian reserve (60.5% of cases). Genetic diagnosis could help to identify patients who may benefit from the promising in vitro activation-IVA technique in the near future, greatly improving its success in treating infertility.

Funding

Université Paris Saclay, Agence Nationale de Biomédecine.

Identification of novel biallelic variants in BMP15 in two siblings with premature ovarian insufficiency

BACKGROUND

Premature ovarian insufficiency (POI) occurs in women before the age of 40 years, accompanied by amenorrhea, hypoestrogenism, hypergonadotropinism, and infertility. The pathology of POI is complex and the molecular genetic mechanisms are poorly understood. Bone morphogenetic protein 15 (BMP15) plays a crucial role in oocyte maturation and follicular development through the activation of granulosa cells. Dysfunction of BMP15 causes ovarian dysgenesis and is related to POI. Identifying pathogenic variants contributes to revealing genetic mechanisms and making clinical diagnoses of POI.

METHODS

The study involved two sisters diagnosed with POI. Whole-exome sequencing (WES) was performed to identify causative genes. Sanger sequencing was used to validate the mutations in patients with POI and members of the family with no clinical signs or symptoms. The effect of the novel mutations on the BMP15 structure was analyzed by PSIPRED. By over-expressing wild-type (WT) or mutant BMP15 plasmids in vitro, a functional study of the BMP15 mutant was conducted by real-time qPCR and western blotting. Through cocultivation with HEK293T cells, the effects of secreted BMP15 WT and variants on granulosa cell proliferation and apoptosis were detected through a cell counting kit-8 assay and flow cytometric analysis.

RESULTS

We identified biallelic variants in BMP15, c.791G > A (p. R264Q) and c.1076C > T (p. P359L), in two siblings with POI. Both sisters carried the same biallelic variants, while the other female members of their family carried only one of them. Structural prediction showed that the variants have not affected the secondary structure of BMP15 but may change the conformation of water molecules around protein surfaces and thermal stability of BMP15. Real-time qPCR showed no significant difference in mRNA levels among WT and the two variants. Western blotting indicated a reduction in BMP15 expression with the c.791G > A and c.1076C > T variants compared to WT. Moreover, mutants 791G > A and 1076C > T impaired the function of secreted BMP15 in promoting granulosa cell proliferation and suppressing cell apoptosis caused by reactive oxygen species.

CONCLUSIONS

This study identified novel biallelic variants, c.791G > A and c.1076C > T, of BMP15 in two siblings with POI. Both missense variants reduced the level of the BMP15 protein and impaired the function of BMP15 in promoting granulosa cell proliferation in vitro. Taken together, our findings provide a novel molecular genetic basis and potential pathogenesis of BMP15 variants in POI.

Differential Expression and Functional Prediction of mRNA in the Ovaries of Hanper Sheep of High and Low Fecundity

Hanper ewes that were either monotocous or polytocous provided ovarian follicles of diameter >3 mm in the follicular phase and, in the luteal phase, samples of corpora lutea that had developed from follicles of diameter >3 mm. Differentially expressed mRNAs (monotocous versus polytocous) were then identified and their functions were predicted. Results showed that 1508 mRNAs were differentially expressed in the follicular phase, with 885 being in the luteal tissues. Those which were differentially expressed in the follicular phase were mainly involved in the regulation of the ferroptosis and lysosome signaling pathways whereas, for the luteal tissue, the differentially expressed mRNAs were mainly involved in the regulation of steroid biosynthesis. Based on the results, it was inferred that these pathways could explain variations in the fecundity of sheep.

Missed opportunities in the treatment of Turner syndrome: a case discussion and review of the guidelines

A woman in her 50s with Turner syndrome was referred to the endocrine clinic, having been unaware of her diagnosis until she received a shielding letter from the UK government during the COVID-19 pandemic. Despite a neonatal diagnosis of Turner syndrome on her general practitioner record and despite having undergone laparoscopic examination for absent puberty and primary amenorrhoea aged 18 years, she had not received any prior hormone treatment or cardiovascular screening.Though Turner syndrome is rare, recent data from the UK Biobank suggest that it may be underdiagnosed. Clinicians should be aware of the clinical features and associated complications of Turner syndrome to avoid delayed diagnosis and missed opportunities for treatment.In this report, we discuss the clinical features of this rare syndrome and current guidelines for screening and treatment. We stress the importance of peer-to-peer support and information sharing through patient-led groups, such as the Turner Syndrome Support Society.

High Throughput Sequencing to Identify Monogenic Etiologies in a Preselected Polycystic Ovary Syndrome Cohort

Context

Polycystic ovary syndrome (PCOS) etiology remains to be elucidated, but familial clustering and twin studies have shown a strong heritable component.

Objective

The purpose of this study was to identify rare genetic variants that are associated with the etiology of PCOS in a preselected cohort.

Methods

This prospective study was conducted among a selected group of women with PCOS. The study’s inclusion criteria were patients with PCOS diagnosed by the Rotterdam criteria with the following phenotypes: severe insulin resistance (IR), normoandrogenic–normometabolic phenotype, adrenal hyperandrogenism, primary amenorrhea, and familial PCOS. Forty-five patients were studied by target sequencing, while 8 familial cases were studied by whole exome sequencing.

Results

Patients were grouped according to the inclusion criteria with the following distribution: 22 (41.5%) with severe IR, 13 (24.5%) with adrenal hyperandrogenism, 7 (13.2%) with normoandrogenic phenotype, 3 (5.7%) with primary amenorrhea, and 8 (15.1%) familial cases. DNA sequencing analysis identified 1 pathogenic variant in LMNA, 3 likely pathogenic variants in INSR, PIK3R1, and DLK1, and 6 variants of uncertain significance level with interesting biologic rationale in 5 genes (LMNA, GATA4, NR5A1, BMP15, and FSHR). LMNA was the most prevalent affected gene in this cohort (3 variants).

Conclusion

Several rare variants in genes related to IR were identified in women with PCOS. Although IR is a common feature of PCOS, patients with extreme or atypical phenotype should be carefully evaluated to rule out monogenic conditions.

Myostatin: a multifunctional role in human female reproduction and fertility - a short review

Myostatin (MSTN) is member of the transforming growth factor β (TGF-β) superfamily and was originally identified in the musculoskeletal system as a negative regulator of skeletal muscle growth. The functional roles of MSTN outside of the musculoskeletal system have aroused researchers' interest in recent years, with an increasing number of studies being conducted in this area. Notably, the expression of MSTN and its potential activities in various reproductive organs, including the ovary, placenta, and uterus, have recently been examined. Numerous studies published in the last few years demonstrate that MSTN plays a critical role in human reproduction and fertility, including the regulation of follicular development, ovarian steroidogenesis, granule-cell proliferation, and oocyte maturation regulation. Furthermore, findings from clinical samples suggest that MSTN may play a key role in the pathogenesis of several reproductive disorders such as uterine myoma, preeclampsia (PE), ovary hyperstimulation syndrome (OHSS), and polycystic ovarian syndrome (PCOS). There is no comprehensive review regarding to MSTN related to the female reproductive system in the literature. This review serves as a summary of the genes in reproductive medicine and their potential influence. We summarized MSTN expression in different compartments of the female reproductive system. Subsequently, we discuss the role of MSTN in both physiological and several pathological conditions related to the female fertility and reproduction-related diseases.

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

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

The Role of Kisspeptin in the Control of the Hypothalamic-Pituitary-Gonadal Axis and Reproduction

The discovery of kisspeptin as a critical central regulatory factor of GnRH release has given people a novel understanding of the neuroendocrine regulation in human reproduction. Kisspeptin activates the signaling pathway by binding to its receptor kisspeptin receptor (KISS1R) to promote GnRH secretion, thereby regulating the hypothalamic-pituitary-gonadal axis (HPG) axis. Recent studies have shown that kisspeptin neurons located in arcuate nucleus (ARC) co-express neurokinin B (NKB) and dynorphin (Dyn). Such neurons are called KNDy neurons. KNDy neurons participate in the positive and negative feedback of estrogen to GnRH secretion. In addition, kisspeptin is a key factor in the initiation of puberty, and also regulates the processes of female follicle development, oocyte maturation, and ovulation through the HPG axis. In male reproduction, kisspeptin also plays an important role, getting involved in the regulation of Leydig cells, spermatogenesis, sperm functions and reproductive behaviors. Mutations in the KISS1 gene or disorders of the kisspeptin/KISS1R system may lead to clinical symptoms such as idiopathic hypogonadotropic hypogonadism (iHH), central precocious puberty (CPP) and female infertility. Understanding the influence of kisspeptin on the reproductive axis and related mechanisms will help the future application of kisspeptin in disease diagnosis and treatment. In this review, we critically appraise the role of kisspeptin in the HPG axis, including its signaling pathways, negative and positive feedback mechanisms, and its control on female and male reproduction.

Strategies for successful designing of immunocontraceptive vaccines and recent updates in vaccine development against sexually transmitted infections - A Review

Background

Objective

Methods

Results

Conclusion

The effect of Kuntai capsule on ovarian function in cisplatin-induced premature ovarian insufficiency rats

OBJECTIVE

This study aims to evaluate the effect of Kuntai capsule on ovarian function in cisplatin-induced premature ovarian insufficiency rats and to explore the mechanism of Kuntai capsule on the ovarian function of rats.

METHODS

Seventy-four female Sprague-Dawley rats were used for this study. Eight of the rats were randomly assigned to the Control group. The remaining sixty-six rats were utilized to establish the POI model via Cisplatin and then randomly divided into four groups: the model Control group, the Estradiol group, and groups treated with low and high doses of Kuntai capsule. For the 28-day administration, the Control and model Control groups were intragastrically administered with 2.0 mL of 0.9% sodium chloride daily, the Estradiol group with 2.0 mL of Estradiol suspension (0.2mg/kg/d), and the low dose Kuntai capsule group and the high dose Kuntai capsule group with 2.0 mL of Kuntai capsule suspension (0.6g/kg/d, 1.8g/kg/d, respectively). Sex hormone levels, estrous cycle, and ovarian coefficient of the five groups were compared, histological sections analyzed follicle counts, and the protein expressions of growth differentiation factor 9, light chain 3 A-II, and Beclin 1 in the ovarian tissue were detected by Western blotting.

RESULTS

After the 28-day administration, the serum Estradiol and Follicle-Stimulating Hormone levels of the group treated with low dose of Kuntai capsule were not significantly different from the Control group, the serum anti-Müllerian Hormone level of the group treated with high dose of Kuntai capsule was significantly higher than the Estradiol group. The estrous cycle of the group treated with low dose of Kuntai capsule was significantly lower than the model Control group. Regarding ovarian coefficient, resting and growing follicles, growth differentiation factor 9, light chain 3 A-II, and Beclin 1 expression, both Kuntai capsule groups outperformed the model Control group with the statistical difference (P<0.05).

CONCLUSION

Kuntai capsule can improve the estrous cycle and ovarian coefficient of rats with premature ovarian insufficiency, maintain the number of resting and growing follicles, and up-regulate the protein expression of growth differentiation factor 9, light chain 3 A-II, and Beclin 1 of rats' ovaries.

Single-Cell Transcriptomics Analysis of Human Small Antral Follicles

Human ovarian folliculogenesis is a highly regulated and complex process. Characterization of follicular cell signatures during this dynamic process is important to understand follicle fate (to grow, become dominant, or undergo atresia). The transcriptional signature of human oocytes and granulosa cells (GCs) in early-growing and ovulatory follicles have been previously described; however, that of oocytes with surrounding GCs in small antral follicles have not been studied yet. Here, we have generated a unique dataset of single-cell transcriptomics (SmartSeq2) consisting of the oocyte with surrounding GCs from several individual (non-dominant) small antral follicles isolated from adult human ovaries. We have identified two main types of (healthy) follicles, with a distinct oocyte and GC signature. Using the CellphoneDB algorithm, we then investigated the bi-directional ligand–receptor interactions regarding the transforming growth factor-β (TGFβ)/bone morphogenetic protein (BMP), wingless-type (MMTV)-integration site (WNT), NOTCH, and receptor tyrosine kinases (RTK) signaling pathways between oocyte and GCs within each antral follicle type. Our work not only revealed the diversity of small antral follicles, but also contributes to fill the gap in mapping the molecular landscape of human folliculogenesis and oogenesis.

The Role of BMP Signaling in Female Reproductive System Development and Function

Bone morphogenetic proteins (BMPs) are a group of multifunctional growth factors that belong to the transforming growth factor-β (TGF-β) superfamily of proteins. Originally identified by their ability to induce bone formation, they are now known as essential signaling molecules that regulate the development and function of the female reproductive system (FRS). Several BMPs play key roles in aspects of reproductive system development. BMPs have also been described to be involved in the differentiation of human pluripotent stem cells (hPSCs) into reproductive system tissues or organoids. The role of BMPs in the reproductive system is still poorly understood and the use of FRS tissue or organoids generated from hPSCs would provide a powerful tool for the study of FRS development and the generation of new therapeutic perspectives for the treatment of FRS diseases. Therefore, the aim of this review is to summarize the current knowledge about BMP signaling in FRS development and function.

Single-Cell RNA-Seq Revealed the Gene Expression Pattern during the In Vitro Maturation of Donkey Oocytes

Donkeys are an important domesticated animal, providing labor, meat, milk, and medicinal materials for humans. However, the donkey population is continuously declining and even at risk of extinction. The application of modern animal production technology, such as oocyte in vitro maturation, is a promising method to improve the donkey population. In this study, we explore the gene expression patterns of donkey germinal vesicle (GV) and in vitro matured metaphase II (MII) oocytes using single cell RNA-seq of the candidate genes along with the regulatory mechanisms that affect donkey oocyte maturation. We identified a total of 24,164 oocyte genes of which 9073 were significant differentially expressed in the GV and MII oocytes. Further Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis indicated that these genes were associated with the meiotic cell cycle, mitochondrion activity, and N-glycan biosynthesis, which might be the key genes and regulatory mechanisms affecting the maturation of donkey oocytes. Our study provides considerable understanding regarding the maturation of donkey oocytes and serves as a theoretical basis for improving the development of donkey oocytes, which could ultimately benefit the expansion of the donkey population and conservation of biodiversity and genetic resources.

The follicular fluid adipocytokine milieu could serve as a prediction tool for fertility treatment outcomes

RESEARCH QUESTION

Can the adipocytokine milieu of the follicular niche improve the ability to predict treatment outcomes in infertile patients?

DESIGN

Follicular fluid samples from overweight patients were analysed and compared with samples from matched normal-weight patients. Concentrations of adiponectin, chemerin, C-reactive protein, interleukin-6 (IL-6), IL-10, IL-18, insulin, leptin, prolactin, resistin, tumour necrosis factor alpha (TNF-α) and bone morphogenetic protein-15 (BMP-15) were assessed by multiple magnetic bead immunoassay (MMBI) and enzyme-linked immunosorbent assay and correlated with fertility treatment outcomes.

RESULTS

Analysis of samples from 22 overweight and 22 normal-weight patients demonstrated that TNF-α can predict oocyte maturation rate. When stratified by body mass index (BMI), IL-10 emerges as a better predictor of oocyte maturation in normal-weight patients. Prolactin was a negative predictor for fertilization rate in the full cohort, and this prediction power was lost upon stratification. No adipocytokines were predictive of blastulation rate, and only age remained predictive. BMP-15 was a strong predictor of high-quality blastulation in the full cohort, more so in the normal-weight population.

CONCLUSIONS

The adipocytokine milieu of the follicular fluid provides a snapshot of the growing oocyte's environment and can help predict fertility treatment outcomes, fine-tuning understanding of the dysregulation caused by increasing BMI. Inflammatory cytokines can predict oocyte maturation; prolactin, oocyte competence; and BMP-15, high-quality blastulation. Further analysis of these findings with a larger sample size and assessing individual oocytes will help shed more light on the clinical significance of these findings.

Two novel mutations in exon 2 of bone morphogenetic protein (BMP) 15 gene in Pakistani infertile females

Objective

To determine the proportion of fertility in Pakistani infertile females and discover if there are considerable connection among BMP15 gene polymorphism, follicle maturation and hormonal regulation in Pakistani infertile females.

Methods

All selected participants were initially examined through follicle-stimulating hormones (FSH), luteinizing hormone (LH), thyroid-stimulating hormone (TSH), Prolactin, and Trans-vaginal scan (TVS). BMP15 gene polymorphism among infertile and fertile females was done by extracted Genomic DNA from whole blood. Sanger sequencing was performed for the identification of mutation in exons-intron boundaries of the BMP15 gene. Bioinformatics tools were used to assess the protein structure.

Results

The total five mutations including two novel missense variants of BMP15 in exon 2, whereas three previously reported i.e. two cosmic mutations (c.615delC), (c.584InsG) and one frame shift mutations (c.635delA) were also observed. The first novel mutation was found at (c.1038InsGG) (p.346Gln < Gly) in which the insertion of GG at DNA position 1038 of exon 2 resulting in a substitution of glutamine into glycine at 346th amino acid of BMP15 protein. The second novel variant (c.1049delT) (p. Ser334Pro) was also observed in exon 2 of the BMP15 gene, which substituted serine into proline at 334th amino acid of the BMP15 protein.

Conclusion

It is concluded that there are various missense mutations present in exon 2 of the BMP15 gene of Pakistani infertile females, consequently expected function of protein changes due to change in codons of amino acids. Provean and SIFT suggest the two novel variants as potentially deleterious. Although three other variants were also found in Pakistani infertile females which were previously reported. These mutations may result in early blockage of folliculogenesis and ovaries become streaky. Further research is required to resolve the actual allusion of these variations in the BMP15 gene.

Alteration of TGFB1, GDF9, and BMPR2 gene expression in preantral follicles of an estradiol valerate-induced polycystic ovary mouse model can lead to anovulation, polycystic morphology, obesity, and absence of hyperandrogenism

Objective

In humans, polycystic ovary syndrome (PCOS) is an androgen-dependent ovarian disorder. Aberrant gene expression in folliculogenesis can arrest the transition of preantral to antral follicles, leading to PCOS. We explored the possible role of altered gene expression in preantral follicles of estradiol valerate (EV) induced polycystic ovaries (PCO) in a mouse model.

Methods

Twenty female balb/c mice (8 weeks, 20.0±1.5 g) were grouped into control and PCO groups. PCO was induced by intramuscular EV injection. After 8 weeks, the animals were killed by cervical dislocation. Blood serum (for hormonal assessments using the enzyme-linked immunosorbent assay technique) was aspirated, and ovaries (the right ovary for histological examinations and the left for quantitative real-time polymerase) were dissected.

Results

Compared to the control group, the PCO group showed significantly lower values for the mean body weight, number of preantral and antral follicles, serum levels of estradiol, luteinizing hormone, testosterone, and follicle-stimulating hormone, and gene expression of TGFB1, GDF9 and BMPR2 (p<0.05). Serum progesterone levels were significantly higher in the PCO animals than in the control group (p<0.05). No significant between-group differences (p>0.05) were found in BMP6 or BMP15 expression.

Conclusion

In animals with EV-induced PCO, the preantral follicles did not develop into antral follicles. In this mouse model, the gene expression of TGFB1, GDF9, and BMPR2 was lower in preantral follicles, which is probably related to the pathologic conditions of PCO. Hypoandrogenism was also detected in this EV-induced murine PCO model.

Molecular Drivers of Developmental Arrest in the Human Preimplantation Embryo: A Systematic Review and Critical Analysis Leading to Mapping Future Research

Developmental arrest of the preimplantation embryo is a multifactorial condition, characterized by lack of cellular division for at least 24 hours, hindering the in vitro fertilization cycle outcome. This systematic review aims to present the molecular drivers of developmental arrest, focusing on embryonic and parental factors. A systematic search in PubMed/Medline, Embase and Cochrane-Central-Database was performed in January 2021. A total of 76 studies were included. The identified embryonic factors associated with arrest included gene variations, mitochondrial DNA copy number, methylation patterns, chromosomal abnormalities, metabolic profile and morphological features. Parental factors included, gene variation, protein expression levels and infertility etiology. A valuable conclusion emerging through critical analysis indicated that genetic origins of developmental arrest analyzed from the perspective of parental infertility etiology and the embryo itself, share common ground. This is a unique and long-overdue contribution to literature that for the first time presents an all-inclusive methodological report on the molecular drivers leading to preimplantation embryos’ arrested development. The variety and heterogeneity of developmental arrest drivers, along with their inevitable intertwining relationships does not allow for prioritization on the factors playing a more definitive role in arrested development. This systematic review provides the basis for further research in the field.

Redox imbalance in age-related ovarian dysfunction and perspectives for its prevention

The age at which women have their first child is increasing. This change represents a major health problem to society because advanced maternal age is related with a decay in fertility and an increase in the incidence of a variety of pregnancy complications and offspring health issues. The ovary stands as the main contributor for female reproductive ageing because of the progressive age-related decrease in follicle number and oocyte quality. Loss of redox homeostasis and establishment of an ovarian oxidative microenvironment are seen as major underlying causes for such downfall and impairment of ovarian function. Thus, the use of antioxidants to preserve fertility became an important field of research. In this review, new insights on mechanisms underlying the establishment of oxidative stress and its repercussions on ovarian ageing are addressed, along with the current state of knowledge on antioxidant supplementation and its contribution for healthy ageing and extension of ovarian lifespan.

Optimizing Fertility in Primary Ovarian Insufficiency: Case Report and Literature Review

Primary ovarian insufficiency (POI) is a clinical spectrum of ovarian dysfunction. Overt POI presents with oligo/amenorrhea and hypergonadotropic hypogonadism before age 40 years. Overt POI involves chronic health problems to include increased morbidity and mortality related to estradiol deficiency and the associated osteoporosis and cardiovascular disease as well as psychological and psychiatric disorders related to the loss of reproductive hormones and infertility. Presently, with standard clinical testing, a mechanism for Overt POI can only be identified in about 10% of cases. Now discovery of new mechanisms permits an etiology to be identified in a research setting in 25-30% of overt cases. The most common genetic cause of Overt POI is premutation in FMR1. The associated infertility is life altering. Oocyte donation is effective, although many women prefer to conceive with their own ova. Surprisingly, the majority who have Overt POI still have detectable ovarian follicles (70%). The major mechanism of follicle dysfunction in Overt POI has been histologically defined by a prospective NIH study: inappropriate follicle luteinization due to the tonically elevated serum LH levels. A trial of physiologic hormone replacement therapy, clinically proven to suppress the elevated LH levels in these women, may improve follicle function and increase the chance of ovulation. Here, we report the case of a woman with Overt POI diagnosed at age 35 years. To attempt pregnancy, she elected a trial of intrauterine insemination (IUI) in conjunction with follicle monitoring and physiologic hormone replacement therapy. She conceived on the eighth cycle of treatment and delivered a healthy baby. Our report calls for a concerted effort to define the best methods by which to optimize fertility for women who have POI.

Effects of bone morphogenetic protein 15 (BMP15) knockdown on porcine testis morphology and spermatogenesis

Bone morphogenetic protein 15 (BMP15) is a member of the transforming growth factor-β (TGFB) superfamily that plays an essential role in mammalian ovary development, oocyte maturation and litter size. However, little is known regarding the expression pattern and biological function of BMP15 in male gonads. In this study we established, for the first time, a transgenic pig model with BMP15 constitutively knocked down by short hairpin (sh) RNA. The transgenic boars were fertile, but sperm viability was decreased. Further analysis of the TGFB/SMAD pathway and markers of reproductive capacity, namely androgen receptor and protamine 2, failed to identify any differentially expressed genes. These results indicate that, in the pig, the biological function of BMP15 in the development of male gonads is not as crucial as in ovary development. However, the role of BMP15 in sperm viability requires further investigation. This study provides new insights into the role of BMP15 in male pig reproduction.

The Role of Bone Morphogenetic Protein 4 in Ovarian Function and Diseases

Bone morphogenetic proteins (BMPs) are the largest subfamily of the transforming growth factor-β (TGF-β) superfamily. BMP4 is a secreted protein that was originally identified due to its role in bone and cartilage development. Over the past decades, extensive literature has indicated that BMP4 and its receptors are widely expressed in the ovary. Dysregulation of BMP4 expression may play a vital role in follicular development, polycystic ovary syndrome (PCOS), and ovarian cancer. In this review, we summarized the expression pattern of BMP4 in the ovary, focused on the role of BMP4 in follicular development and steroidogenesis, and discussed the role of BMP4 in ovarian diseases such as polycystic ovary syndrome and ovarian cancer. Some studies have shown that the expression of BMP4 in the ovary is spatiotemporal and species specific, but the effects of BMP4 seem to be similar in follicular development of different species. In addition, BMP4 is involved in the development of hyperandrogenemia in PCOS and drug resistance in ovarian cancer, but further research is still needed to clarify the specific mechanisms.

ERβ regulated ovarian kisspeptin plays an important role in oocyte maturation

Kisspeptin (KISS1) signaling in the hypothalamic-pituitary (H-P) axis plays an essential role in regulating gonadotropin secretion. KISS1 and KISS1 receptor (KISS1R) are also expressed in the ovary; however, the role of intraovarian KISS1 signaling remains unclear. Granulosa cell (GC)-specific expression of KISS1, and oocyte-specific expression of KISS1R indicate that GC-derived KISS1 may act on oocytes. Expression of KISS1 in GCs is induced by gonadotropins but it is absent in estrogen receptor β knockout (Erβ^null) rat ovaries. We also observed that gonadotropin stimulation failed to induce maturation of Erβ^null oocytes. Interestingly, KISS1 treatment of cumulus oocyte complexes (COCs) isolated from antral follicles promotes in vitro maturation of oocytes. Treatment of oocytes with KISS1 induced intracellular Ca²⁺ release, and increased activation of MAP kinase ERK1/2. KISS1 treatment also induced the expression of oocyte genes that are crucial for differentiation of GCs, and maturation of oocytes. Our findings suggest that ovarian KISS1-signaling plays an important role in gonadotropin induced follicle development and oocyte maturation.

Exploratory analysis of serum concentrations of oocyte biomarkers growth differentiation factor 9 and bone morphogenetic protein 15 in ovulatory women across the menstrual cycle

OBJECTIVE

To characterize and evaluate the variation in serum concentrations of oocyte-secreted growth differentiation factor 9 (GDF9) and bone morphogenetic protein 15 (BMP15) throughout the menstrual cycle in women from young to advanced reproductive ages.

DESIGN

Cross-sectional, observational, and exploratory study.

SETTING

Multicenter university-based clinical practices and laboratories.

PATIENT(S)

Serum was collected every 1-3 days throughout the menstrual cycle from 3 cohorts of healthy, ovulatory women: menses to late luteal phase (21-29 years of age; n = 16; University of Otago) and across one interovulatory interval (18-35 years of age; n = 10; and 45-50 years of age; n = 15; University of Saskatchewan).

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

To detect the changes in serum GDF9 and BMP15 across the cycle, mean concentration and variance were statistically modeled using a generalized additive model of location, shape and scale (GAMLSS). Follicle-stimulating hormone, luteinizing hormone, estradiol, progesterone, and anti-Müllerian hormone were also assessed.

RESULT(S)

GDF9 and BMP15 were detectable in 54% and 73% of women and varied 236-fold and 52-fold between women, respectively. Across the menstrual cycle, there were minimal changes in GDF9 or BMP15 within a woman for all cohorts, with no significant differences detected in the modeled mean concentrations. However, modeled variances were highest in the luteal phases of all women for BMP15 immediately after ovulation, regardless of age.

CONCLUSION(S)

Serial changes in GDF9 or BMP15 concentrations across the cycle were not statistically detected and are likewise similar across the reproductive lifespan. Further research is required to fully elucidate the utility of these oocyte biomarkers at diagnosing fertility potential and/or disease.

Bone morphogenetic protein 15 supplementation enhances cumulus expansion, nuclear maturation and progesterone production of in vitro-matured bovine cumulus-oocyte complexes

In vitro embryo production (IVP) efficiency is reduced when compared to in vivo. The basic knowledge of bovine in vitro oocyte maturation (IVM) mechanisms provides support to improve in vitro embryo production yields. The present study assessed the effects of bone morphogenetic protein 15 (BMP15), fibroblast growth factor 16 (FGF16) and their combined action on cumulus cells (CC) expansion, oocyte and CC DNA fragmentation, oocyte nuclear maturation, energetic metabolism and progesterone production in bovine IVM. Cumulus-oocyte complexes (COC) were matured in control or supplemented media containing BMP15 (100 ng/ml), FGF16 (10 ng/ml) or BMP15 combined with FGF16; and assessed at 0 and 22 hr of IVM. BMP15 alone or its association with FGF16 enhanced cumulus expansion. BMP15 decreased DNA fragmentation in both CC and oocytes, and improved oocyte nuclear maturation rate. In addition, BMP15 increased CC progesterone production, an effect not previously reported. The present study reinforces previous data pointing to a beneficial influence of BMP15 during IVM, while providing novel evidence that the underlying mechanisms involve increased progesterone production.

Cell-specific network analysis of human folliculogenesis reveals network rewiring in antral stage oocytes

Although previous studies have explored the gene expression profiles of human oocytes and granulosa cells by single-cell RNA sequencing (scRNA-seq), the dynamic regulatory network at a single-cell resolution during folliculogenesis remains largely unknown. We identified 10 functional modules by WGCNA, four of which were significantly correlated with primary/antral oocyte and antral/pre-ovulatory granulosa cells. Functional enrichment analysis showed that the brown module, which was correlated with antral oocyte, was enriched in oocyte differentiation, and two core subnetworks identified by MCODE were involved in cell cycle (blue subnetwork) and oogenesis (red subnetwork). The cell-specific network (CSN) analysis demonstrated a distinct gene network structure associated with the antral follicular stage, which was notably different from other developmental stages. To our knowledge, this is the first study to explore gene functions during folliculogenesis at single-cell network level. We uncovered two potential gene subnetworks, which may play an important role in oocyte function beginning at the antral stage, and further established their rewiring process at intra-network/whole transcriptome level. The findings provide crucial insights from a novel network perspective to be further explored in functional mechanistic studies.

Transforming growth factor-β superfamily and interferon-τ in ovarian function and embryo development in female cattle: review of biology and application

Survival of the embryo and establishment of a pregnancy is a critical period in the reproductive function of female cattle. This review examines how the transforming growth factor-β (TGFB) superfamily (i.e. bone morphogenetic protein (BMP) 15, growth differentiation factor (GDF) 9, anti-Müllerian hormone (AMH)) and interferon-τ (IFNT) affect ovarian function and embryo development. The oocyte in a primary follicle secretes BMP15 and GDF9, which, together, organise the surrounding granulosa and theca cells into the oocyte-cumulus-follicle complex. At the same time, the granulosa secretes AMH, which affects the oocyte. This autocrine-paracrine dialogue between the oocyte and somatic cells continues throughout follicle development and is fundamental in establishing the fertilisation potential and embryo developmental competency of oocytes. The early bovine embryo secretes IFNT, which acts at the uterine endometrium, corpus luteum and blood leucocytes. IFNT is involved in the maternal recognition of pregnancy and immunomodulation to prevent rejection of the embryo, and supports progesterone secretion. Manipulation of BMP15, GDF9, AMH and IFNT in both invivo and invitro studies has confirmed their importance in reproductive function in female cattle. This review makes the case that a deeper understanding of the biology of BMP15, GDF9, AMH and IFNT will lead to new strategies to increase embryo survival and improve fertility in cattle. The enhancement of oocyte quality, early embryo development and implantation is considered necessary for the next step change in the efficiency of natural and assisted reproduction in cattle.

A nonsense mutation of bone morphogenetic protein-15 (BMP15) causes both infertility and increased litter size in pigs

Background

Atypical external genitalia are often a sign of reproductive organ pathologies and infertility with both environmental or genetic causes, including karyotypic abnormalities. Genome-wide association studies (GWAS) provide a means for identifying chromosomal regions harboring deleterious DNA-variants causing such phenotypes. We performed a GWAS to unravel the causes of incidental cases of atypically small vulvae in German Landrace gilts.

Results

A case-control GWAS involving Illumina porcine SNP60 BeadChip-called genotypes of 17 gilts with atypically small vulvae and 1818 control animals (fertile German Landrace sows) identified a significantly associated region on the X-chromosome (P = 8.81 × 10^− 43). Inspection of whole-genome sequencing data in the critical area allowed us to pinpoint a likely causal variant in the form of a nonsense mutation of bone morphogenetic protein-15 (BMP15; Sscrofa11.1_X:g.44618787C>T, BMP15:p.R212X). The mutant allele occurs at a frequency of 6.2% in the German Landrace breeding population. Homozygous gilts exhibit underdeveloped, most likely not functional ovaries and are not fertile. Male carriers do not seem to manifest defects. Heterozygous sows produce 0.41±0.02 (P=4.5 × 10^-83) piglets more than wildtype animals. However, the mutant allele’s positive effect on litter size accompanies a negative impact on lean meat growth.

Conclusion

Our results provide an example for the power of GWAS in identifying the genetic causes of a fuzzy phenotype and add to the list of natural deleterious BMP15 mutations that affect fertility in a dosage-dependent manner, the first time in a poly-ovulatory species. We advise eradicating the mutant allele from the German Landrace breeding population since the adverse effects on the lean meat growth outweigh the larger litter size in heterozygous sows.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-020-07343-x.

Utilizing Calcium Alginate for the Assessment of Bone Morphogenetic Protein 15 Induction Effect on the Differentiation of Mesenchymal Stem Cell Derived from Human Follicular Fluid to Oocyte-Like Structure

Background:

Follicular fluid (FF)-derived mesenchymal stem cells (MSCs) are possible new source of cells in the study of oogenesis and regenerative medicine. Several biomaterials have been used as scaffolds to mimic ovarian tissue stroma. Using good matrix is essential for increasing the cell survival rate, proliferation, and differentiation. However, no study has been performed to investigate the effects of BMP15 and calcium alginate hydrogel on the differentiation potential of FF-derived MSCs to oocyte-like structures (OLSs).

Materials and Methods:

In this work, FF MSCs, which were collected from women in routine in vitro fertilization procedure, were capsulated with 0.5% calcium alginate, and then the encapsulated cells were cultured in medium containing BMP15 for 2 weeks. Trypan blue staining was carried out to determine cell viability. Real-time polymerase chain reaction (PCR) and immunofluorescence (ICC) staining method were performed to characterize the expression of OCT4, Nanog, ZP2, and ZP3 genes and protein. The encapsulation process did not change the morphology and viability of the encapsulated cells.

Results:

Reverse-transcription-PCR and ICC showed that MSCs expressed germ line stem cell markers such as OCT4 and Nanog. After 4 days of culture, OLSs formed and expressed zona pellucida markers. OLSs at least reached 180–230 μm in diameter in the control and BMP15-treated groups. Finally, a reduction in the expression pattern of pluripotency and ZP markers was detected in the encapsulated cells cultured in the BMP15-supplemented medium.

Conclusion:

The three-dimensional alginate culture system seems to be a promising method of getting in vitro differentiation and development of ovarian cells, which could mimic the native ovarian condition.