Role and mechanism of AMH in the regulation of Sertoli cells in mice

Effect of Inhibin Immunization on Reproductive Hormones and Testicular Morphology of Dezhou Donkeys During the Non-Breeding Season

The present study was designed to investigate the potential role of inhibin immunization on plasma hormone concentration and testicular histoarchitecture of Dezhou donkeys in the nonbreeding season (November-February). For this purpose, adult Dezhou donkeys (n = 30) were equally divided into groups A, B, and C. Group A was actively immunized with 3 mg inhibin, group B with (1.5 mg), and group C was immunized with Bovine serum albumin (BSA) and served as a control. All animals in groups A and B were given a primary dose of inhibin (INH) antigen, i.e., 3 mg and 1.5 mg on day 1, followed by a booster dose on the 23rd day of the experiment. Blood samples were collected on the 21st, 28th, 34th, and 40th days of the experiment. Primary and booster INH immunization (3 mg and 1.5 mg) slightly elevated the plasma hormone concentrations of FSH, LH, AMH, and Activin A. The number of spermatogonia was significantly higher in group A as compared to group C on the 28th day of the experiment. Inhibin immunization also caused apoptosis in testicular histoarchitecture. In conclusion, Inhibin immunization can potentially improve the reproductive efficiency of Dezhou donkeys in a nonbreeding season by elevating plasma hormone concentrations of FSH, LH, AMH, and Activin A.

Anti-Müllerian hormone regulates ovarian granulosa cell growth in PCOS rats through SMAD4

OBJECTIVE

Polycystic ovary syndrome (PCOS) is a diverse condition with an unknown cause. The precise mechanism underlying ovulatory abnormalities in PCOS remains unclear. It is widely believed that malfunction of granulosa cells is the primary factor contributing to aberrant follicular formation in PCOS.

METHODS

A DHEA-induced PCOS rat model was established, and ovarian granulosa cells were extracted and identified. Anti-Müllerian hormone (AMH) and SMAD family member 4 (SMAD4) expression was detected in the serum, ovarian tissue and ovarian granulosa cells of each group, and proliferating cell nuclear antigen (PCNA), BCL2-associated 2 (BAX), cleaved caspase-3 and BCL-2 protein expression was detected by Western blot in ovarian granulosa cells. Recombinant anti-Müllerian hormone (rAMH) was administered at different concentrations to act on normal rat ovarian granulosa cells, cell proliferation was detected by cell counting kit-8 (CCK-8), apoptosis was detected by flow cytometry, and SMAD4, caspase-3, BCL-2 and cyclin A proteins were detected by Western blot. SMAD4-siRNA was transfected into rat ovarian granulosa cells of the PCOS group, and PCNA and BAX were detected by Western blot.

RESULTS

Compared with those in the control group, the expression of AMH and SMAD4 was increased in the ovarian tissues and granulosa cells of rats in the PCOS group, the expression of PCNA and BCL-2 proteins was decreased in the ovarian granulosa cells of the PCOS group, the expression of BAX proteins was increased, and the expression of cleaved caspase-3 was increased. Western blot results indicated that rAMH upregulated SMAD4 and caspase-3 protein expression in granulosa cells and downregulated cyclin A and BCL-2 protein expression. CCK-8 and flow cytometry results indicated that AMH decreased granulosa cells proliferation and increased apoptosis. SiRNA knockdown of SMAD4 gene increased PCNA and BCL-2 protein expression in the granulosa cells of PCOS rats and decreased BAX and cleaved caspase-3 protein expression.

CONCLUSION

AMH may be involved in regulating impaired ovarian granulosa cells development in PCOS rats via SMAD4.

Research progress on Sertoli cell secretion during spermatogenesis

Sertoli cells (SCs), as the somatic cells in the testis of male mammals, play a crucial role in the close association with germ cells. The blood-testicular barrier (BTB), established by their tight junctions, provides immune protection to germ cells, leading to their characterization as "sentinel" cells. Moreover, the physiological process of testicular development and spermatogenesis in male animals is intricately tied to the secretory activities of SCs. These cells secrete a diverse array of proteins and cytokines that interact with various targets, working in concert with mechanisms in the spermatogenesis pathway and contributing to each stage, from spermatogonial cell division to the maturation of spermatozoa. Hence, the secretory products of SCs are pivotal in fostering germ cell development and directing the appropriate maturation of sperm. This study is dedicated to investigating the varied secretions of SCs, outlining their critical functions throughout distinct phases of spermatogenesis, thus elucidating the substantial influence of SC secretion on male fertility. Furthermore, it offers valuable perspectives on reproductive disorders stemming from irregular spermatogenesis in clinical contexts.

Enhanced endoplasmic reticulum stress signaling disrupts porcine sertoli cell function in response to Bisphenol A exposure

Bisphenol A (BPA), a pervasive substance in our daily lives and livestock excreta, poses significant threats due to its infiltration into foods and water sources. BPA has adverse impacts on male reproductive function, particularly affecting the critical Sertoli (ST) cells that play a pivotal role in the process of spermatogonia differentiating into spermatozoa. In this study, we examined the prevalence of BPA within the pig industry and delved into the impact of BPA exposure on the motility of boar sperm, the function of pig ST cells, as well as the underlying molecular mechanisms involved. This study revealed spatial disparities in the global distribution of BPA and its analogue contamination, utilizing data compiled from 130 comprehensive studies. The average concentration of BPA found in pig feed ranges from 9.7 to 47.9 μg/kg, while in serum, it averages between 55.1 and 75.6 ng/L. The BPA concentration in feed exhibits a negative correlation with sperm viability and the percentage of progressive motile spermatozoa. Exposure to BPA reduced sperm motility in boar and ST cell activity at both 6 and 24 h. The transcriptome analysis revealed that, compared to untreated control cells, endoplasmic reticulum stress (ERS)-related genes were upregulated in ST cells exposed to BPA at 6 and 24 h. This activation of ERS in ST cells was mediated by receptor protein kinase RNA-like endoplasmic reticulum kinase (PERK), inositol-requiring protein-1α (IRE1α), and activating transcription factor 6 (ATF6). Additionally, BPA exposure triggered oxidative stress and a proinflammatory response mediated by the transcription factor NF-κB, accompanied by an increase in downstream proinflammatory cytokines. BPA exposure also led to apoptosis in ST cells and upregulated the expression levels of pro-apoptosis proteins. However, inhibiting ERS activity with 4-PBA attenuated the BPA-induced inflammatory response and apoptosis in ST cells. Our findings suggest that BPA induced apoptosis and inflammatory response in porcine ST cells through persistent activation of ERS, thereby compromising the normal function of these cells.

Anti-Müllerian hormone: biology and role in endocrinology and cancers

Anti-Müllerian hormone (AMH) is a peptide belonging to the transforming growth factor beta superfamily and acts exclusively through its receptor type 2 (AMHR2). From the 8th week of pregnancy, AMH is produced by Sertoli cells, and from the 23rd week of gestation, it is produced by granulosa cells of the ovary. AMH plays a critical role in regulating gonadotropin secretion, ovarian tissue responsiveness to pituitary hormones, and the pathogenesis of polycystic ovarian syndrome. It inhibits the transition from primordial to primary follicles and is considered the best marker of ovarian reserve. Therefore, measuring AMH concentration of the hormone is valuable in managing assisted reproductive technologies. AMH was initially discovered through its role in the degeneration of Müllerian ducts in male fetuses. However, due to its ability to inhibit the cell cycle and induce apoptosis, it has also garnered interest in oncology. For example, antibodies targeting AMHR2 are being investigated for their potential in diagnosing and treating various cancers. Additionally, AMH is present in motor neurons and functions as a protective and growth factor. Consequently, it is involved in learning and memory processes and may support the treatment of Alzheimer's disease. This review aims to provide a comprehensive overview of the biology of AMH and its role in both endocrinology and oncology.

Different expression patterns of DNA methyltransferases during horse testis development

DNA methyltransferases (DNMTs) are important epigenetic modification during spermatogenesis. To further evaluate the pattern of DNMTs in horse testes during development, we investigated the expression and localization of DNMT1, DNMT3a and DNMT3b at different time points. The qRT-PCR results showed that DNMT1 expression was maintained in testes tissue from 6-month-old (0.5y) to 2-year-old (2y) of age and decreased after 3-year-old (3y) (P < 0.01). The expression levels of DNMT3a and DNMT3b peaked in testes tissue at 3y (P < 0.01). At 4-year-old (4y), the expression of DNMT3a and DNMT3b was decreased and became similar to that at 0.5y. Immunofluorescence of DNMT1, DNMT3a and DNMT3b on testis samples confirmed the differential expression and localization of these three DNA methylation transferases during horse development. Further molecular biological studies are needed to understand the implications of the expression patterns of these DNMTs in horse testes.

Col3a1 delivered via extracellular vesicles of Sertoli cells is essential for mice Sertoli cell proliferation

It is generally believed that Sertoli cells can proliferate only before sexual maturity. In this study, we found that extracellular vesicles of Sertoli cells derived from prepubertal mice (SEVs) have the ability to promote the proliferation of Sertoli cell population. In addition, via proteomic analysis, we compared the functional components of extracellular vesicles derived from Sertoli cells of mice at 12-14 days and 8 weeks. The functional profiling of SEVs suggested important developmental roles, and this was confirmed by analysis comparing the transcriptomic changes in Sertoli cells treated with DMSO and GW4869. The following analysis pointed to Col3a1 as a key factor in SEVs, which was further validated using primary Sertoli cells and TM4 cell line. The present study suggests a possible role for Col3a1 in promoting the proliferation of cultured Sertoli cells and provides a new perspective on the function of extracellular vesicles in Sertoli cell development.

Potential Role of Anti-Müllerian Hormone in Regulating Seasonal Reproduction in Animals: The Example of Males

Seasonal reproduction is a survival strategy by which animals adapt to environmental changes to improve their fitness. Males are often characterized by a significantly reduced testicular volume, indicating that they are in an immature state. Although many hormones, including gonadotropins, have played a role in testicular development and spermatogenesis, research on other hormones is insufficient. The anti-Müllerian hormone (AMH), which is a hormone responsible for inducing the regression of Müllerian ducts involved in male sex differentiation, was discovered in 1953. Disorders in AMH secretion are the main biomarkers of gonadal dysplasia, indicating that it may play a crucial role in reproduction regulation. A recent study has found that the AMH protein is expressed at a high level during the non-breeding period of seasonal reproduction in animals, implying that it may play a role in restricting breeding activities. In this review, we summarize the research progress on the AMH gene expression, regulatory factors of the gene's expression, and its role in reproductive regulation. Using males as an example, we combined testicular regression and the regulatory pathway of seasonal reproduction and attempted to identify the potential relationship between AMH and seasonal reproduction, to broaden the physiological function of AMH in reproductive suppression, and to provide new ideas for understanding the regulatory pathway of seasonal reproduction.

Reproductive Suppression Caused by Spermatogenic Arrest: Transcriptomic Evidence from a Non-Social Animal

Reproductive suppression is an adaptive strategy in animal reproduction. The mechanism of reproductive suppression has been studied in social animals, providing an essential basis for understanding the maintenance and development of population stability. However, little is known about it in solitary animals. The plateau zokor is a dominant, subterranean, solitary rodent in the Qinghai-Tibet Plateau. However, the mechanism of reproductive suppression in this animal is unknown. We perform morphological, hormonal, and transcriptomic assays on the testes of male plateau zokors in breeders, in non-breeders, and in the non-breeding season. We found that the testes of non-breeders are smaller in weight and have lower serum testosterone levels than those of breeders, and the mRNA expression levels of the anti-Müllerian hormone (AMH) and its transcription factors are significantly higher in non-breeder testes. Genes related to spermatogenesis are significantly downregulated in both meiotic and post-meiotic stages in non-breeders. Genes related to the meiotic cell cycle, spermatogenesis, flagellated sperm motility, fertilization, and sperm capacitation are significantly downregulated in non-breeders. Our data suggest that high levels of AMH may lead to low levels of testosterone, resulting in delayed testicular development, and physiological reproductive suppression in plateau zokor. This study enriches our understanding of reproductive suppression in solitary mammals and provides a basis for the optimization of managing this species.

Impact of endocrine disrupting chemicals and pharmaceuticals on Sertoli cell development and functions

Sertoli cells play essential roles in male reproduction, from supporting fetal testis development to nurturing male germ cells from fetal life to adulthood. Dysregulating Sertoli cell functions can have lifelong adverse effects by jeopardizing early processes such as testis organogenesis, and long-lasting processes such as spermatogenesis. Exposure to endocrine disrupting chemicals (EDCs) is recognized as contributing to the rising incidence of male reproductive disorders and decreasing sperm counts and quality in humans. Some drugs also act as endocrine disruptors by exerting off-target effects on endocrine tissues. However, the mechanisms of toxicity of these compounds on male reproduction at doses compatible with human exposure are still not fully resolved, especially in the case of mixtures, which remain understudied. This review presents first an overview of the mechanisms regulating Sertoli cell development, maintenance, and functions, and then surveys what is known on the impact of EDCs and drugs on immature Sertoli cells, including individual compounds and mixtures, and pinpointing at knowledge gaps. Performing more studies on the impact of mixtures of EDCs and drugs at all ages is crucial to fully understand the adverse outcomes these chemicals may induce on the reproductive system.

New AMH cutoff values for warning of decreased ovarian response based on MCL characteristics in young women: a retrospective study using a propensity score-matching analysis

BACKGROUND

Menstrual cycle length (MCL) and ovarian response varies widely among women of childbearing age. They are provided with anti-Mu¨llerian hormone (AMH) cutoffs for "normal" and "weakened" ovarian responses, which give an early warning of the onset of decreased ovarian response.

METHODS

This was a retrospective study in women aged 21 to 35 years with MCLs of 21-35 days receiving in vitro fertilization (IVF) treatment at Center for Reproductive Medicine from October 2018 to October 2021. Intergroup variables were balanced using propensity score matching based on age and BMI, and each case patient (patients with MCLs of 21-25 days) was matched with three control patients (patients with MCLs of 26-35 days). A receiver operating characteristic curve was used to calculate the AMH cutoff values.

RESULTS

We included 135 patients with MCLs of 21-25 days and 405 matched control patients with MCLs of 26-35 days who received IVF treatment. The case group had significantly fewer retrieved oocytes, lower AMH values and higher initial and total Gonadotropin (Gn) levels during controlled ovarian hyperstimulation than the control group. The ovarian response began to decrease when AMH was < 3.5 ng/ml in the case group and < 2.7 ng/ml in the control group.

CONCLUSION

In young women with MCLs of 21-35 days, short MCL was negatively correlated with AMH values and the number of oocytes retrieved. In patients with MCLs of 21-25 days and 26-35 days, the AMH cutoff values corresponding to the onset of decreased ovarian response were 3.5 ng/ml and 2.7 ng/ml, respectively.

Phthalate plasticizer decreases the prion-like protein doppel essential for structural integrity and function of spermatozoa

Di-n-butyl phthalate (DBP), a well-known endocrine disruptor, causes male reproductive dysfunction. To understand the underlying mechanisms, we performed histological, endocrinological, and biochemical analyses and assessed the expression of genes involved in spermatogenesis and sperm function according to OECD test guideline 407. Following 28 days of administration of the lowest observed adverse effect level dose of DBP to mice, no significant changes in body weight, testis and epididymis weights and histology, serum testosterone level, or testicular daily sperm production were found. Nonetheless, the motility of the epididymal sperm of the DBP group was significantly decreased together with an increase in the incidence of bent tails and abnormal heads. In the testes of the DBP group, lipid peroxidation (LPO) level was significantly increased and testicular Bcl-2 mRNA level was significantly decreased together with an increase in the Bax/Bcl-2 mRNA ratio. In the testes of the DBP group, levels of Prnd mRNA and protein and Pou4f1 mRNA, an activator of the Prnd promotor, were significantly decreased. Of note, prion-like protein doppel (PRND) was significantly decreased together with decreased PRND immunoreactivity in the head, midpiece, and tail of sperm. In the testes of the DBP group, levels of Sox9, Sgp1, and Sgp2 mRNA, which are functional Sertoli cell markers, were significantly decreased. Level of Amh mRNA, a Sertoli cell immaturity marker, was significantly increased together with that of Inha mRNA, suggesting deregulation of the brain-gonadal axis. Together, our findings suggest that DBP at present dosage may potentiate LPO generation and Sertoli cell immaturity via downregulation of Sox9 and disruption of the Pou4f1-Prnd gene network in post-meiotic germ cells without visible changes in spermatogenesis or testosterone level. This may result in structural and functional abnormalities in spermatozoa. Additionally, our findings suggest that assessment of the male reproductive toxicity of phthalate ester plasticizers based on conventional OECD test guidelines should be reconsidered.

Anti-Müllerian Hormone and Polycystic Ovary Syndrome in Women and Its Male Equivalent

This article reviews the main findings on anti-Müllerian hormone (AMH) and its involvement in the pathogenesis of polycystic ovary syndrome (PCOS) and its male equivalent. In women, AMH is produced by granulosa cells from the mid-fetal life to menopause and is a reliable indirect marker of ovarian reserve. AMH protects follicles from atresia, inhibits their differentiation in the ovary, and stimulates gonadotrophin-releasing hormone neurons pulsatility. AMH overexpression in women with PCOS likely contributes to the increase of the follicle cohort and of androgen levels, leading to follicular arrest and anovulation. In the male, AMH is synthesized at high levels by Sertoli cells from fetal life to puberty when serum AMH falls to levels similar to those observed in women. AMH is involved in the differentiation of the genital tract during fetal life and plays a role in Sertoli and Leydig cells differentiation and function. Serum AMH is used to assess Sertoli cell function in children with disorders of sex development and various conditions affecting the hypothalamic–pituitary–testicular axis. Although the reproductive function of male relative of women with PCOS has been poorly investigated, adolescents have elevated levels of AMH which could play a detrimental role on their fertility.

Immature rat testis sustained long-term development using an integrative model

BACKGROUND

Xenotransplantation has been primarily performed using fresh donor tissue to study testicular development for about 20 years, and whether the cultured tissue would be a suitable donor is unclear. In this study, we combined testicular culture and xenotransplantation into an integrative model and explored whether immature testicular tissue would survive and continue to develop in this model.

METHODS

In the new integrative model group, the testes of neonatal rats on postnatal day 8 (PND 8) were cultured for 4 days ex vivo and then were transplanted under the dorsal skin of castrated nude mice. The xenografted testes were resected on the 57th day after xenotransplantation and the testes of rats in the control group were harvested on PND 69. The survival state of testicular tissue was evaluated from morphological and functional perspectives including H&E staining, immunohistochemical staining of 8-OH-dG, immunofluorescence staining, TUNEL assay, ultrastructural study, gene expression and protein analysis.

RESULTS

(a) We found that complete spermatogenesis was established in the testes in the new integrative model group. Compared with the control in the same stage, the seminiferous epithelium in some tubules was a bit thinner and there were vacuoles in part of the tubules. Immunofluorescence staining revealed some ACROSIN-positive spermatids were present in seminiferous tubule of xenografted testes. TUNEL detection showed apoptotic cells and most of them were germ cells in the new integrative model group. 8-OH-dG immunohistochemistry showed strongly positive-stained in the seminiferous epithelium after xenotransplantation in comparison with the control group; (b) Compared with the control group, the expressions of FOXA3, DAZL, GFRα1, BOLL, SYCP3, CDC25A, LDHC, CREM and MKI67 in the new integrative model group were significantly elevated (P < 0.05), indicating that the testicular tissue was in an active differentiated and proliferative state; (c) Antioxidant gene detection showed that the expression of Nrf2, Keap1, NQO1 and SOD1 in the new integrative model group was significantly higher than those in the control group (P < 0.05), and DNA methyltransferase gene detection showed that the expression of DNMT3B was significantly elevated as well (P < 0.05).

CONCLUSION

The new integrative model could maintain the viability of immature testicular tissue and sustain the long-term survival in vivo with complete spermatogenesis. However, testicular genes expression was altered, vacuolation and thin seminiferous epithelium were still apparent in this model, manifesting that oxidative damage may contribute to the testicular development lesion and it needs further study in order to optimize this model.

Anti-Müllerian hormone stimulates expression of the collagen-specific chaperone 47-kDa heat shock protein in bovine uterine epithelial cells

Uterine collagen is the most abundant component of the uterine extracellular matrix and plays a critical role in pregnancy. The 47-kDa heat shock protein (HSP47) is the sole collagen-specific molecular chaperone. We investigated the mechanisms regulating the expression of HSP47 in the uterus by assessing the effect of anti-Müllerian hormone (AMH) stimulation on HSP47 expression in cultured bovine uterine epithelial cells. AMH receptor type 2 (AMHR2), AMH, and HSP47 expression was assessed by fluorescence immunocytochemistry in uterine epithelial layers of the uteri of Japanese Black cows. The effect of AMH on HSP47 expression was assessed in cultured epithelial cells. The effect of MEK/ERK inhibitor on AMH-induced HSP47 expression was also assessed. We confirmed the expression of AMHR2, AMH, and HSP47 in the uterine epithelial layers. We confirmed the expression of AMHR2, AMH, HSP47, and type IV collagen in cultured uterine epithelial cells. AMH treatment at 10 or 100 ng/ml promoted significant HSP47 expression (p < 0.05). MEK/ERK inhibitor U0126 pretreatment suppressed such AMH stimulation on HSP47. These findings indicate that AMH induced HSP47 protein expression through the ERK pathway in bovine uterine epithelial cells.

MicroRNA-125a-5p modulates the proliferation and apoptosis of TM4 Sertoli cells by targeting RAB3D and regulating the PI3K/AKT signaling pathway

Sertoli cells are cells that provide protection and nutrition for developing sperm. Each stage of sperm development occurs on the surface of Sertoli cells. MicroRNA (MiR)-125a-5p is involved in male reproduction. The current research aimed to probe the role of miR-125a-5p in Sertoli cell function. Functionally, miR-125a-5p knockdown facilitated Sertoli cell proliferation, while miR-125a-5p overexpression suppressed Sertoli cell proliferation, as evidenced by 5-ethynyl-20-deoxyuridine incorporation assay. Additionally, miR-125a-5p knockdown inhibited Sertoli cell apoptosis, while miR-125a-5p upregulation facilitated Sertoli cell apoptosis, as evidenced by flow cytometry analysis. Computationally, we identified four predicted mRNA targets of miR-125a-5p. Based on the results of luciferase reporter assay, miR-125a-5p was confirmed to bind to the predicted sequence in the Ras-related protein Rab-3D (RAB3D) 3'UTR. Rescue experiments showed that miR-125a-5p suppressed the proliferative ability of TM4 Sertoli cells and facilitated their apoptosis by targeting RAB3D. Finally, our data confirmed that miR-125a-5p and RAB3D modulated activation of the PI3K/AKT pathway. In conclusion, our data showed that miR-125a-5p regulated Sertoli cell proliferation and apoptosis by targeting RAB3D and regulating the PI3K/AKT pathway.

Specific Transcriptomic Signatures and Dual Regulation of Steroidogenesis Between Fetal and Adult Mouse Leydig Cells

Leydig cells (LC) are the main testicular androgen-producing cells. In eutherian mammals, two types of LCs emerge successively during testicular development, fetal Leydig cells (FLCs) and adult Leydig cells (ALCs). Both display significant differences in androgen production and regulation. Using bulk RNA sequencing, we compared the transcriptomes of both LC populations to characterize their specific transcriptional and functional features. Despite similar transcriptomic profiles, a quarter of the genes show significant variations in expression between FLCs and ALCs. Non-transcriptional events, such as alternative splicing was also observed, including a high rate of intron retention in FLCs compared to ALCs. The use of single-cell RNA sequencing data also allowed the identification of nine FLC-specific genes and 50 ALC-specific genes. Expression of the corticotropin-releasing hormone 1 (Crhr1) receptor and the ACTH receptor melanocortin type 2 receptor (Mc2r) specifically in FLCs suggests a dual regulation of steroidogenesis. The androstenedione synthesis by FLCs is stimulated by luteinizing hormone (LH), corticotrophin-releasing hormone (CRH), and adrenocorticotropic hormone (ACTH) whereas the testosterone synthesis by ALCs is dependent exclusively on LH. Overall, our study provides a useful database to explore LC development and functions.

Testicular germ cell tumors arise in the absence of sex-specific differentiation

In response to signals from the embryonic testis, the germ cell intrinsic factor NANOS2 coordinates a transcriptional program necessary for the differentiation of pluripotent-like primordial germ cells toward a unipotent spermatogonial stem cell fate. Emerging evidence indicates that genetic risk factors contribute to testicular germ cell tumor initiation by disrupting sex-specific differentiation. Here, using the 129.MOLF-Chr19 mouse model of testicular teratomas and a NANOS2 reporter allele, we report that the developmental phenotypes required for tumorigenesis, including failure to enter mitotic arrest, retention of pluripotency and delayed sex-specific differentiation, were exclusive to a subpopulation of germ cells failing to express NANOS2. Single-cell RNA sequencing revealed that embryonic day 15.5 NANOS2-deficient germ cells and embryonal carcinoma cells developed a transcriptional profile enriched for MYC signaling, NODAL signaling and primed pluripotency. Moreover, lineage-tracing experiments demonstrated that embryonal carcinoma cells arose exclusively from germ cells failing to express NANOS2. Our results indicate that NANOS2 is the nexus through which several genetic risk factors influence tumor susceptibility. We propose that, in the absence of sex specification, signals native to the developing testis drive germ cell transformation.

Anti-Müllerian hormone (AMH) autocrine signaling promotes survival and proliferation of ovarian cancer cells

In ovarian carcinoma, anti-Müllerian hormone (AMH) type II receptor (AMHRII) and the AMH/AMHRII signaling pathway are potential therapeutic targets. Here, AMH dose-dependent effect on signaling and proliferation was analyzed in four ovarian cancer cell lines, including sex cord stromal/granulosa cell tumors and high grade serous adenocarcinomas (COV434-AMHRII, SKOV3-AMHRII, OVCAR8 and KGN). As previously shown, incubation with exogenous AMH at concentrations above the physiological range (12.5-25 nM) decreased cell viability. Conversely, physiological concentrations of endogenous AMH improved cancer cell viability. Partial AMH depletion by siRNAs was sufficient to reduce cell viability in all four cell lines, by 20% (OVCAR8 cells) to 40% (COV434-AMHRII cells). In the presence of AMH concentrations within the physiological range (5 to 15 pM), the newly developed anti-AMH B10 antibody decreased by 25% (OVCAR8) to 50% (KGN) cell viability at concentrations ranging between 3 and 333 nM. At 70 nM, B10 reduced clonogenic survival by 57.5%, 57.1%, 64.7% and 37.5% in COV434-AMHRII, SKOV3-AMHRII, OVCAR8 and KGN cells, respectively. In the four cell lines, B10 reduced AKT phosphorylation, and increased PARP and caspase 3 cleavage. These results were confirmed in ovarian cancer cells isolated from patients' ascites, demonstrating the translational potential of these results. Furthermore, B10 reduced COV434-MISRII tumor growth in vivo and significantly enhanced the median survival time compared with vehicle (69 vs 60 days; p = 0.0173). Our data provide evidence for a novel pro-survival autocrine role of AMH in the context of ovarian cancer, which was targeted therapeutically using an anti-AMH antibody to successfully repress tumor growth.

Genetic evidence for Amh modulation of gonadotropin actions to control gonadal homeostasis and gametogenesis in zebrafish and its noncanonical signaling through Bmpr2a receptor

Anti-Müllerian hormone (Amh) plays an important role in gonadal function. Amh deficiency causes severe gonadal dysgenesis and dysfunction in zebrafish, with gonadal hypertrophy in both sexes. However, its mechanism of action remains unknown. Intriguingly, the Amh cognate type II receptor (Amhr2) is missing in the zebrafish genome, in sharp contrast to other species. Using a series of zebrafish mutants (amh, fshb, fshr and lhcgr), we provided unequivocal evidence for actions of Amh, via modulation of gonadotropin signaling, on both germ cell proliferation and differentiation. The gonadal hypertrophy in amh mutants was abolished in the absence of Fshr in females or Fshr/Lhcgr in males. Furthermore, we demonstrated that knockout of bmpr2a, but not bmpr2b, phenocopied all phenotypes of the amh mutant in both sexes, including gonadal hypertrophy, hyperproliferation of germ cells, retarded gametogenesis and reduced fshb expression. In summary, the present study provided comprehensive genetic evidence for an intimate interaction of gonadotropin and Amh pathways in gonadal homeostasis and gametogenesis and for Bmpr2a as the possible missing link for Amh signaling in zebrafish.

Anti-Müllerian hormone (Amh/amh) plays dual roles in maintaining gonadal homeostasis and gametogenesis in zebrafish

Anti-Müllerian hormone (AMH/Amh) plays a role in gonadal differentiation and function across vertebrates. In zebrafish we demonstrated that Amh deficiency caused severe gonadal dysgenesis and dysfunction. The mutant gonads showed extreme hypertrophy with accumulation of early germ cells in both sexes, namely spermatogonia in the testis and primary growth oocytes in the ovary. In amh mutant females, the folliculogenesis was normal in young fish but receded progressively in adults, which was accompanied by progressive decrease in follicle-stimulating hormone (fshb) expression. Interestingly the expression of fshb increased in the pituitary of juvenile amh mutant males but decreased in adults. The upregulation of fshb in mutant male juveniles was likely one of the mechanisms for triggering gonadal hypergrowth, whereas the downregulation of fshb in adults might involve a negative feedback by gonadal inhibin. Further analysis using mutants of fshb and growth differentiation factor 9 (gdf9) provided evidence for a role of FSH in triggering ovarian hypertrophy in young female amh mutant as well. In summary, the present study provided comprehensive genetic evidence for dual roles of Amh in controlling zebrafish gonadal homeostasis and gametogenesis in both sexes. Amh suppresses proliferation or accumulation of early germ cells (spermatogonia in testis and primary growth oocytes in ovary) while promoting their exit to advanced stages, and its action may involve both endocrine and paracrine pathways.

Stage-dependent actions of antimüllerian hormone in regulating granulosa cell proliferation and follicular function in the primate ovary

OBJECTIVE

To study the direct action and physiological role of antimüllerian hormone (AMH) in regulating ovarian follicular development and function in vivo in primates.

DESIGN

Animals were assigned to six treatment sequences in a crossover design study. Intraovarian infusion was performed during the follicular phase of the menstrual cycle with agents including: control vehicle; recombinant human AMH (rhAMH); and neutralizing anti-human AMH antibody (AMHAb). Before ovariectomy after the final treatment, the animals received intravenous injections of bromodeoxyuridine (BrdU).

SETTING

National primate research center.

ANIMALS

Adult female rhesus macaques (Macaca mulatta).

INTERVENTIONS

None.

MAIN OUTCOME MEASURES

Cycle length, follicle cohorts, and serum steroid levels were assessed. Ovarian histology, as well as granulosa cell (GC) proliferation and oocyte viability, were evaluated.

RESULTS

In vehicle-infused ovaries, a dominant follicle was observed at midcycle E2 peak. However, rhAMH-treated ovaries exhibited an increased number of small antral follicles, whereas AMHAb-treated ovaries developed multiple large antral follicles. Serum E2 levels in the follicular phase decreased after rhAMH infusion and increased after AMHAb infusion. The rhAMH infusion increased serum T levels. Whereas early-growing follicles of rhAMH-treated ovaries contained BrdU-positive GCs, antral follicles containing BrdU-positive GCs were identified in AMHAb-treated ovaries. Autophagy was observed in oocytes of early-growing and antral follicles exposed to AMHAb and rhAMH, respectively.

CONCLUSIONS

AMH enhanced early-stage follicle growth, but prevented antral follicle development and function via its stage-dependent regulation of GC proliferation and oocyte viability. This study provides information relevant to the pathophysiology of ovarian dysfunction and the treatment of infertility.

The regulation and signalling of anti-Müllerian hormone in human granulosa cells: relevance to polycystic ovary syndrome

STUDY QUESTION

What prevents the fall in anti-Müllerian hormone (AMH) levels in polycystic ovary syndrome (PCOS) and what are the consequences of this for follicle progression in these ovaries?

SUMMARY ANSWER

Exposure of granulosa cells (GCs) to high levels of androgens, equivalent to that found in PCOS, prevented the fall in AMH and was associated with dysregulated AMH-SMAD signalling leading to stalled follicle progression in PCOS.

WHAT IS KNOWN ALREADY

In normal ovaries, AMH exerts an inhibitory role on antral follicle development and a fall in AMH levels is a prerequisite for ovulation. Levels of AMH are high in PCOS, contributing to the dysregulated follicle growth that is a common cause of anovulatory infertility in these women.

STUDY DESIGN, SIZE, DURATION

Human KGN-GC (the cell line that corresponds to immature GC from smaller antral follicles (AF)) were cultured with a range of doses of various androgens to determine the effects on AMH production. KGN-GC were also treated with PHTPP (an oestrogen receptor β (ERβ) antagonist) to examine the relationship between AMH expression and the ratio of ERα:ERβ. The differential dose-related effect of AMH on gene expression and SMAD signalling was investigated in human granulosa-luteal cells (hGLC) from women with normal ovaries, with polycystic ovarian morphology (PCOM) and with PCOS. KGN-GC were also cultured for a prolonged period with AMH at different doses to assess the effect on cell proliferation and viability.

PARTICIPANTS/MATERIALS, SETTING, METHODS

AMH protein production by cells exposed to androgens was measured by ELISA. The effect of PHTPP on the mRNA expression levels of AMH, ERα and ERβ was assessed by real-time quantitative PCR (qPCR). The influence of AMH on the relative mRNA expression levels of aromatase, AMH and its receptor AMHRII, and the FSH and LH receptor (FSHR and LHR) in control, PCOM and PCOS hGLCs was quantified by qPCR. Western blotting was used to assess changes in levels of SMAD proteins (pSMAD-1/5/8; SMAD-4; SMAD-6 and SMAD-7) after exposure of hGLCs from healthy women and women with PCOS to AMH. The ApoTox-Glo Triplex assay was used to evaluate the effect of AMH on cell viability, cytotoxicity and apoptosis.

MAIN RESULTS AND THE ROLE OF CHANCE

Testosterone reduced AMH protein secreted from KGN-GC at 10-9-10-7 M (P < 0.05; P < 0.005, multiple uncorrected comparisons Fishers least squares difference), but at equivalent hyperandrogenemic levels no change was seen in AMH levels. 5α-DHT produced a significant dose-related increase in AMH protein secreted into the media (P = 0.022, ANOVA). Increasing the mRNA ratio of ERα:ERβ produced a corresponding increase in AMH mRNA expression (P = 0.015, two-way ANOVA). AMH increased mRNA levels of aromatase (P < 0.05, one-way ANOVA) and FSHR (P < 0.0001, one-way ANOVA) in hGLCs from women with PCOM, but not from normal cells or PCOS (normal n = 7, PCOM n = 5, PCOS n = 4). In contrast to hGLCs from ovulatory ovaries, in PCOS AMH reduced protein levels (cell content) of stimulatory pSMAD-1/5/8 and SMAD-4 but increased inhibitory SMAD-6 and -7 (P < 0.05, normal n = 6, PCOS n = 3). AMH at 20 and 50 ng/ml decreased KGN-GC cell proliferation but not viability after 8 days of treatment (P < 0.005, two-way ANOVA).

LARGE SCALE DATA

N/A.

LIMITATIONS, REASONS FOR CAUTION

Luteinised GC from women undergoing IVF have a relatively low expression of AMH/AMHRII but advantageously continue to display responses inherent to the ovarian morphology from which they are collected. To compensate, we also utilised the KGN cell line which has been characterised to be at a developmental stage close to that of immature GC. The lack of flutamide influence on testosterone effects is not in itself sufficient evidence to conclude that the effect on AMH is mediated via conversion to oestrogen, and the effect of aromatase inhibitors or oestrogen-specific inhibitors should be tested. The effect of flutamide was tested on testosterone but not DHT.

WIDER IMPLICATIONS OF THE FINDINGS

Normal folliculogenesis and ovulation are dependent on the timely reduction in AMH production from GC at the time of follicle selection. Our findings reveal for the first time that theca-derived androgens may play a role in this model but that this inhibitory action is lost at levels of androgens equivalent to those seen in PCOS. The AMH decline may either be a direct effect of androgens or an indirect one via conversion to oestradiol and acting through the upregulation of ERα, which is known to stimulate the AMH promoter. Interestingly, the ability of GCs to respond to this continually elevated AMH level appears to be reduced in cells from women with PCOS due to an adaptive alteration in the SMAD signalling pathway and lower expression of AMHRII, indicating a form of 'AMH resistance'.

STUDY FUNDING/COMPETING INTEREST(S)

This study was funded by the Thomas Addison Scholarship, St Georges Hospital Trust. The authors report no conflict of interest in this work and have nothing to disclose.

TRIAL REGISTRATION NUMBER

N/A.

Zebrafish as an emerging model to study gonad development

The zebrafish (Danio rerio) has emerged as a popular model organism in developmental biology and pharmacogenetics due to its attribute of pathway conservation. Coupled with the availability of robust genetic and transgenic tools, transparent embryos and rapid larval development, studies of zebrafish allow detailed cellular analysis of many dynamic processes. In recent decades, the cellular and molecular mechanisms involved in the process of gonad development have been the subject of intense research using zebrafish models. In this mini-review, we give a brief overview of these studies, and highlight the essential genes involved in sex determination and gonad development in zebrafish.

Primary Sertoli Cell Cultures From Adult Mice Have Different Properties Compared With Those Derived From 20-Day-Old Animals

Cultures of Sertoli cells isolated from 20-day-old mice are widely used in research as substitutes for adult Sertoli cell cultures. This practice is based on the fact that Sertoli cells cease to proliferate and become mature in vivo by 16 to 20 days after birth. However, it is important to verify whether cultured Sertoli cells derived from 20-day-old mice do not proliferate ex vivo and whether they have the same properties as cultured adult Sertoli cells. Herein we described an isolation/culture method of Sertoli cells from 10-week-old adult mice with > 90% purity. Properties of these cultured adult Sertoli cells were then compared with those of cultured Sertoli cells derived from 20-day-old mice (also > 90% purity). By cell counting, bromo-2-deoxyuridine incorporation, and metaphase plate detection, we demonstrated that only adult Sertoli cells did not proliferate throughout 12 culture days. In contrast, Sertoli cells derived from 20-day-old mice still proliferated until Day 10 in culture. The morphology and profiles of intracellular lipidomics and spent medium proteomics of the 2 cultures were also different. Cultured adult Sertoli cells were larger in size and contained higher levels of triacylglycerols, cholesteryl esters, and seminolipid, and the proteins in their spent medium were mainly engaged in cellular metabolism. In contrast, proteins involved in cell division, including anti-Mullerian hormone, cell division cycle protein 42 (CDC42), and collagen isoforms, were at higher levels in Sertoli cell cultures derived from 20-day-old mice. Therefore, cultured Sertoli cells derived from 10-week-old mice, rather than those from 20-day-old animals, should be used for studies on properties of adult Sertoli cells.

Fine Mapping Using Whole-Genome Sequencing Confirms Anti-Müllerian Hormone as a Major Gene for Sex Determination in Farmed Nile Tilapia (Oreochromis niloticus L.)

Nile tilapia (Oreochromis niloticus) is one of the most cultivated and economically important species in world aquaculture. Intensive production promotes the use of monosex animals, due to an important dimorphism that favors male growth. Currently, the main mechanism to obtain all-male populations is the use of hormones in feeding during larval and fry phases. Identifying genomic regions associated with sex determination in Nile tilapia is a research topic of great interest. The objective of this study was to identify genomic variants associated with sex determination in three commercial populations of Nile tilapia. Whole-genome sequencing of 326 individuals was performed, and a total of 2.4 million high-quality bi-allelic single nucleotide polymorphisms (SNPs) were identified after quality control. A genome-wide association study (GWAS) was conducted to identify markers associated with the binary sex trait (males = 1; females = 0). A mixed logistic regression GWAS model was fitted and a genome-wide significant signal comprising 36 SNPs, spanning a genomic region of 536 kb in chromosome 23 was identified. Ten out of these 36 genetic variants intercept the anti-Müllerian (Amh) hormone gene. Other significant SNPs were located in the neighboring Amh gene region. This gene has been strongly associated with sex determination in several vertebrate species, playing an essential role in the differentiation of male and female reproductive tissue in early stages of development. This finding provides useful information to better understand the genetic mechanisms underlying sex determination in Nile tilapia.

Heat shock factor 1 protects germ cell proliferation during early ovarian differentiation in medaka

The heat shock response is important for the viability of all living organisms. It involves the induction of heat shock proteins whose expression is mainly regulated by heat shock factor 1 (HSF1). Medaka (Oryzias latipes) is a teleost fish with an XX/XY sex determination system. High water temperature (HT) inhibits the female-type proliferation of germ cells and induces the masculinisation of XX medaka in some cases during gonadal sex differentiation. Here, we investigated the roles of HSF1 on the proliferation of germ cells using HSF1 knockout medaka. Loss of HSF1 function under HT completely inhibited the female-type proliferation of germ cells, induced the expression of the anti-Mullerian hormone receptor type 2 (amhr2) and apoptosis-related genes, and suppressed that of the dead end (dnd) and heat shock protein-related genes. Moreover, the loss of HSF1 and AMHR2 function under HT recovered female-type proliferation in germ cells, while loss of HSF1 function under HT induced gonadal somatic cell apoptosis during early sex differentiation. These results strongly suggest that HSF1 under the HT protects the female-type proliferation of germ cells by inhibiting amhr2 expression in gonadal somatic cells. These findings provide new insights into the molecular mechanisms underlying environmental sex determination.