A novel member of the transmembrane serine/threonine kinase receptor family is specifically expressed in the gonads and in mesenchymal cells adjacent to the mullerian duct

Anti-Müllerian hormone signalling sustains circadian homeostasis in zebrafish

Circadian clocks temporally orchestrate the behavioural and physiological rhythms. The core molecules establishing the circadian clock are clear; however, the critical signalling pathways that cause or favour the homeostasis are poorly understood. Here, we report that anti-Müllerian hormone (Amh)-mediated signalling plays an important role in sustaining circadian homeostasis in zebrafish. Notably, amh knockout dampens molecular clock oscillations and disrupts both behavioural and hormonal circadian rhythms, which are recapitulated in bmpr2a null mutants. Somatotropes and gonadotropes are identified as Amh-targeted pituitary cell populations. Single-cell transcriptome analysis further reveals a lineage-specific regulation of pituitary clock by Amh. Moreover, Amh-induced effect on clock gene expression can be abolished by blocking Smad1/5/9 phosphorylation and bmpr2a knockout. Mechanistically, Amh binds to its receptors, Bmpr2a/Bmpr1bb, which in turn activate Smad1/5/9 by phosphorylation and promote circadian gene expression. Our findings reveal a key hormone signalling pathway for circadian homeostasis in zebrafish with implications for rhythmic organ functions and circadian health.

Transforming growth factor beta signaling and craniofacial development: modeling human diseases in zebrafish

Humans and other jawed vertebrates rely heavily on their craniofacial skeleton for eating, breathing, and communicating. As such, it is vital that the elements of the craniofacial skeleton develop properly during embryogenesis to ensure a high quality of life and evolutionary fitness. Indeed, craniofacial abnormalities, including cleft palate and craniosynostosis, represent some of the most common congenital abnormalities in newborns. Like many other organ systems, the development of the craniofacial skeleton is complex, relying on specification and migration of the neural crest, patterning of the pharyngeal arches, and morphogenesis of each skeletal element into its final form. These processes must be carefully coordinated and integrated. One way this is achieved is through the spatial and temporal deployment of cell signaling pathways. Recent studies conducted using the zebrafish model underscore the importance of the Transforming Growth Factor Beta (TGF-β) and Bone Morphogenetic Protein (BMP) pathways in craniofacial development. Although both pathways contain similar components, each pathway results in unique outcomes on a cellular level. In this review, we will cover studies conducted using zebrafish that show the necessity of these pathways in each stage of craniofacial development, starting with the induction of the neural crest, and ending with the morphogenesis of craniofacial elements. We will also cover human skeletal and craniofacial diseases and malformations caused by mutations in the components of these pathways (e.g., cleft palate, craniosynostosis, etc.) and the potential utility of zebrafish in studying the etiology of these diseases. We will also briefly cover the utility of the zebrafish model in joint development and biology and discuss the role of TGF-β/BMP signaling in these processes and the diseases that result from aberrancies in these pathways, including osteoarthritis and multiple synostoses syndrome. Overall, this review will demonstrate the critical roles of TGF-β/BMP signaling in craniofacial development and show the utility of the zebrafish model in development and disease.

Anti-Müllerian Hormone promotes human osteoblast differentiation and calcification by modulating osteogenic gene expression

OBJECTIVE

To investigate whether the Anti-Müllerian Hormone (AMH), an ovarian hormone belonging to the Transforming Growth Factor β superfamily, may represent a possible candidate for use as a bone anabolic factor.

METHODS

We performed in vitro studies on Human Osteoblasts (HOb) to evaluate the expression and the functionality of AMHRII, the AMH receptor type-2, and investigate the effects of exogenous AMH exposure on osteogenic gene expression and osteoblast functions.

RESULTS

We reported the first evidence for the expression and functionality of AMHRII in HOb cells, thus suggesting that osteoblasts may represent a specific target for exogenous AMH treatment. Furthermore, the exposure to AMH exerted a stimulatory effect on HOb cells leading to the activation of osteogenic genes, including the upregulation of osteoblastic transcription factors such as RUNX and OSX, along with increased deposition of mineralized nodules.

CONCLUSION

Our findings proved interesting clues on the stimulatory effects of AMH on mature osteoblasts expressing its specific receptor, AMHRII. This study may therefore have translation value in opening the perspective that AMH may be an effective candidate to counteract the bone loss in osteoporotic patients by selectively targeting osteoblast with minimal off-target effect.

A transgenic bacterial artificial chromosome approach to identify regulatory regions that direct Amhr2 and Osterix expression in Müllerian duct mesenchyme

A transgenic mouse approach using bacterial artificial chromosomes (BAC) was used to identify regulatory regions that direct Müllerian duct expression for Amhr2 and Osterix (Osx, also known as Sp7). Amhr2 encodes the receptor that mediates anti-Müllerian hormone (AMH) signaling for Müllerian duct regression in male embryos. Amhr2 is expressed in the Müllerian duct mesenchyme of both male and female embryos. A ∼147-kb BAC clone containing the Amhr2 locus was used to generate transgenic mice. The transgene was able to rescue the block in Müllerian duct regression of Amhr2-null males, suggesting that the BAC clone contains regulatory sequences active in male embryos. Osx is expressed in the developing skeleton of male and female embryos but is also an AMH-induced gene that is expressed in the Müllerian duct mesenchyme exclusively in male embryos. Osx-Cre transgenic mice were previously generated using a ∼204-kb BAC clone. Crosses of Osx-Cre mice to Cre-dependent lacZ reporter mice resulted in reporter expression in the developing skeleton and in the Müllerian duct mesenchyme of male but not female embryos. Osx-Cherry transgenic mice were previously generated using a 39-kb genomic region surrounding the Osx locus. Osx-Cherry embryos expressed red fluorescence in the developing skeleton and Müllerian duct mesenchyme of male but not female embryos. In addition, female Osx-Cherry embryos ectopically expressing human AMH from an Mt1-AMH transgene activated red fluorescence in the Müllerian duct mesenchyme. These results suggest that the 39-kb region used to generate Osx-Cherry contains male-specific Müllerian duct mesenchyme regulatory sequences that are responsive to AMH signaling. These BAC transgenic mouse approaches identify two distinct regions that direct Müllerian duct mesenchyme expression and contribute fundamental knowledge to define a gene regulatory network for sex differentiation.

Clusterin negatively modulates mechanical stress-mediated ligamentum flavum hypertrophy through TGF-β1 signaling

Ligamentum flavum hypertrophy (LFH) is a major cause of lumbar spinal canal stenosis (LSCS). The pathomechanisms for LFH have not been fully elucidated. Isobaric tags for relative and absolute quantitation (iTRAQ) technology, proteomics assessments of human ligamentum flavum (LF), and successive assays were performed to explore the effect of clusterin (CLU) upregulation on LFH pathogenesis. LFH samples exhibited higher cell positive rates of the CLU, TGF-β1, α-SMA, ALK5 and p-SMAD3 proteins than non-LFH samples. Mechanical stress and TGF-β1 initiated CLU expression in LF cells. Notably, CLU inhibited the expression of mechanical stress-stimulated and TGF-β1-stimulated COL1A2 and α-SMA. Mechanistic studies showed that CLU inhibited mechanical stress-stimulated and TGF-β1-induced SMAD3 activities through suppression of the phosphorylation of SMAD3 and by inhibiting its nuclear translocation by competitively binding to ALK5. PRKD3 stabilized CLU protein by inhibiting lysosomal distribution and degradation of CLU. CLU attenuated mechanical stress-induced LFH in vivo. In summary, the findings showed that CLU attenuates mechanical stress-induced LFH by modulating the TGF-β1 pathways in vitro and in vivo. These findings imply that CLU is induced by mechanical stress and TGF-β1 and inhibits LF fibrotic responses via negative feedback regulation of the TGF-β1 pathway. These findings indicate that CLU is a potential treatment target for LFH.

The protein clusterin regulates the body’s response to lower back pain induced by mechanical stress and could be a target for treatments. Lower back pain is common and is exacerbated by our upright stance. A major cause of the pain is excessive cell growth (hypertrophy) in the ligaments between vertebrae. This growth narrows the spinal canal and compresses nerves. Using a unique mouse model bred to walk upright, Zhongmin Zhang and Liang Wang at Southern Medical University in Guangzhou, China, and co-workers showed that clusterin, a protein involved in regulation of cell survival, can reduce the hypertrophy caused by mechanical stresses, and could be used in back pain treatments. Clusterin regulates the activity of the growth factor TGF-β1, which plays a role in synthesizing new tissues after injury, but can spur excessive growth.

Molecular Mechanisms of AMH Signaling

Anti-Müllerian Hormone (AMH) is a secreted glycoprotein hormone with critical roles in reproductive development and regulation. Its chemical and mechanistic similarities to members of the Transforming Growth Factor β (TGF-β) family have led to its placement within this signaling family. As a member of the TGF-β family, AMH exists as a noncovalent complex of a large N-terminal prodomain and smaller C-terminal mature signaling domain. To produce a signal, the mature domain will bind to the extracellular domains of two type I and two type II receptors which results in an intracellular SMAD signal. Interestingly, as will be discussed in this review, AMH possesses several unique characteristics which set it apart from other ligands within the TGF-β family. In particular, AMH has a dedicated type II receptor, Anti-Müllerian Hormone Receptor Type II (AMHR2), making this interaction intriguing mechanistically as well as therapeutically. Further, the prodomain of AMH has remained largely uncharacterized, despite being the largest prodomain within the family. Recent advancements in the field have provided valuable insight into the molecular mechanisms of AMH signaling, however there are still many areas of AMH signaling not understood. Herein, we will discuss what is known about the biochemistry of AMH and AMHR2, focusing on recent advances in understanding the unique characteristics of AMH signaling and the molecular mechanisms of receptor engagement.

Clinical Utility of Anti-Mullerian Hormone in Pediatrics

CONTEXT

Anti-Mullerian hormone (AMH) was originally described in the context of sexual differentiation in the male fetus but has gained prominence now as a marker of ovarian reserve and fertility in females. In this mini-review, we offer an updated synopsis on AMH and its clinical utility in pediatric patients.

DESIGN AND RESULTS

A systematic search was undertaken for studies related to the physiology of AMH, normative data, and clinical role in pediatrics. In males, AMH, secreted by Sertoli cells, is found at high levels prenatally and throughout childhood and declines with progression through puberty to overlap with levels in females. Thus, serum AMH has clinical utility as a marker of testicular tissue in males with differences in sexual development and cryptorchidism and in the evaluation of persistent Mullerian duct syndrome. In females, serum AMH has been used as a predictive marker of ovarian reserve and fertility, but prepubertal and adolescent AMH assessments need to be interpreted cautiously. AMH is also a marker of tumor burden, progression, and recurrence in germ cell tumors of the ovary.

CONCLUSIONS

AMH has widespread clinical diagnostic utility in pediatrics but interpretation is often challenging and should be undertaken in the context of not only age and sex but also developmental and pubertal stage of the child. Nonstandardized assays necessitate the need for assay-specific normative data. The recognition of the role of AMH beyond gonadal development and maturation may usher in novel diagnostic and therapeutic applications that would further expand its utility in pediatric care.

Anti-Müllerian Hormone Signal Transduction involved in Müllerian Duct Regression

Over seventy years ago it was proposed that the fetal testis produces a hormone distinct from testosterone that is required for complete male sexual development. At the time the hormone had not yet been identified but was invoked by Alfred Jost to explain why the Müllerian duct, which develops into the female reproductive tract, regresses in the male fetus. That hormone, anti-Müllerian hormone (AMH), and its specific receptor, AMHR2, have now been extensively characterized and belong to the transforming growth factor-β families of protein ligands and receptors involved in growth and differentiation. Much is now known about the downstream events set in motion after AMH engages AMHR2 at the surface of specific Müllerian duct cells and initiates a cascade of molecular interactions that ultimately terminate in the nucleus as activated transcription factors. The signals generated by the AMH signaling pathway are then integrated with signals coming from other pathways and culminate in a complex gene regulatory program that redirects cellular functions and fates and leads to Müllerian duct regression.

Distal-less homeobox genes Dlx5/6 regulate Müllerian duct regression

Dlx5 and Dlx6 encode distal-less homeodomain transcription factors that are present in the genome as a linked pair at a single locus. Dlx5 and Dlx6 have redundant roles in craniofacial, skeletal, and uterine development. Previously, we performed a transcriptome comparison for anti-Müllerian hormone (AMH)-induced genes expressed in the Müllerian duct mesenchyme of male and female mouse embryos. In that study, we found that Dlx5 transcripts were nearly seven-fold higher in males compared to females and Dlx6 transcripts were found only in males, suggesting they may be AMH-induced genes. Therefore, we investigated the role of Dlx5 and Dlx6 during AMH-induced Müllerian duct regression. We found that Dlx5 was detected in the male Müllerian duct mesenchyme from E14.5 to E16.5. In contrast, in female embryos Dlx5 was detected in the Müllerian duct epithelium. Dlx6 expression in Müllerian duct mesenchyme was restricted to males. Dlx6 expression was not detected in female Müllerian duct mesenchyme or epithelium. Genetic experiments showed that AMH signaling is necessary for Dlx5 and Dlx6 expression. Müllerian duct regression was variable in Dlx5 homozygous mutant males at E16.5, ranging from regression like controls to a block in Müllerian duct regression. In E16.5 Dlx6 homozygous mutants, Müllerian duct tissue persisted primarily in the region adjacent to the testes. In Dlx5-6 double homozygous mutant males Müllerian duct regression was also found to be incomplete but more severe than either single mutant. These studies suggest that Dlx5 and Dlx6 act redundantly to mediate AMH-induced Müllerian duct regression during male differentiation.

Anti-Müllerian Hormone in Female Reproduction

Anti-Müllerian hormone (AMH), also called Müllerian inhibiting substance, was shown to be synthesized by the ovary in the 1980s. This article reviews the main findings of the past 20 years on the regulation of the expression of AMH and its specific receptor AMHR2 by granulosa cells, the mechanism of action of AMH, the different roles it plays in the reproductive organs, its clinical utility, and its involvement in the principal pathological conditions affecting women. The findings in respect of regulation tell us that AMH and AMHR2 expression is mainly regulated by bone morphogenetic proteins, gonadotropins, and estrogens. It has now been established that AMH regulates the different steps of folliculogenesis and that it has neuroendocrine effects. On the other hand, the importance of serum AMH as a reliable marker of ovarian reserve and as a useful tool in the prediction of the polycystic ovary syndrome (PCOS) and primary ovarian failure has also been acknowledged. Last but not least, a large body of evidence points to the involvement of AMH in the pathogenesis of PCOS.

A novel mutation of AMHR2 in two brothers with persistent Müllerian duct syndrome and their intracytoplasmic sperm injection outcome

Background

Persistent Müllerian duct syndrome (PMDS) is defined as the presence of Müllerian duct derivatives in an otherwise normally virilized 46, XY male. It is usually caused by homozygous or compound heterozygous mutations in either the anti‐Müllerian hormone (AMH) or AMH receptor type 2 (AMHR2) genes. The main purpose of the study is to determine the novel mutations of AMHR2 in PMDS patients and their intracytoplasmic sperm injection outcomes (ICSI).

Methods

Whole‐exome sequencing (WES) was carried out. Sanger sequencing was used to detect mutations in AMHR2. The pathogenicity of the identified variant and its possible effects on the protein were evaluated with in silico tools. The expression level of AMHR2 was determined by Western blotting. The spermatogenic function was evaluated by testicular sperm aspiration and histopathologic examination. The ICSI outcomes were recorded.

Results

We present two brothers with a history of bilateral cryptorchidism with orchidopexy and infertility due to azoospermia. A novel compound heterozygous mutation of c.1219C>T [p.R407X] and c.1387C>T [p.R463C] in exons 9 and 10 of AMHR2 (NM_020547.2) was detected by whole‐exome sequencing (WES). Spermatozoon could be retrieved from the two patients by testicular aspiration following intracytoplasmic sperm injection (ICSI) due to azoospermia. Finally, patient 1 had two healthy boys and patient 2 failed to conceive after three ICSI attempts.

Conclusion

The spermatozoa could obtain from PMDS patients due to azoospermia. For patients with bilateral cryptorchidism, PMDS should be included in the differential diagnosis and that genetic counseling needs to be considered when they seek reproductive help.

Identification of four novel variant in the AMHR2 gene in six unrelated Turkish families

PURPOSE

Persistent Müllerian duct syndrome (PMDS) is characterized by the persistence of Müllerian structures in male with normal phenotype. Most cases occur as a result of mutations in the anti-Müllerian hormone (AMH) or AMHR2 genes. In this study, we aim to discuss the results of clinical, laboratory, and molecular genetic analysis of cases detected to have AMHR2 gene mutation.

METHODS

A total of 11 cases from 6 families were included in the study. AMHR2 gene mutation analyses were performed by sequencing of the coding exons and the exon-intron boundaries of the genes. The American College of Medical Genetics guidelines were used for the classification of the detected variants.

RESULTS

Six of the 11 cases were admitted due to bilateral undescended testes and five cases due to inguinal hernia (three transverse testicular ectopia and two hernia uterus inguinalis). All cases had normal AMH levels. Seven different variants were identified in the six families. The variants detected in four cases were considered novel (c.78del, c.71G > A, c.1460dup, c.1319A > G). Two of the novel variants were missense (exon 2 and exon 10) mutations, one was deletion (exon 2), and one duplication (exon 11).

CONCLUSION

We identified four novel mutations in the AMHR2 gene resulting in PMDS. Duplication mutation (c.1460dup) in the AMHR2 gene causing PMDS was demonstrated for the first time. The most important complications of PMDS are infertility and malignancy. Early diagnosis is vital to preventing malignancy. Vas deferens and vascular structures may be injured during orchiopexy. Therefore, patients should always be referred to experienced clinics.

In Vivo Cell Fate Tracing Provides No Evidence for Mesenchymal to Epithelial Transition in Adult Fallopian Tube and Uterus

The mesenchymal to epithelial transition (MET) is thought to be involved in the maintenance, repair, and carcinogenesis of the fallopian tube (oviduct) and uterine epithelium. However, conclusive evidence for the conversion of mesenchymal cells to epithelial cells in these organs is lacking. Using embryonal cell lineage tracing with reporters driven by mesenchymal cell marker genes of the female reproductive tract (AMHR2, CSPG4, and PDGFRβ), we show that these reporters are also expressed by some oviductal and uterine epithelial cells at birth. These mesenchymal reporter-positive epithelial cells are maintained in adult mice across multiple pregnancies, respond to ovarian hormones, and form organoids. However, no labeled epithelial cells are present in any oviductal or uterine epithelia when mesenchymal cell labeling was induced in adult mice. Organoids developed from mice labeled in adulthood were also negative for mesenchymal reporters. Collectively, our work found no definitive evidence of MET in the adult fallopian tube and uterine epithelium.

Mesenchymal to epithelial transition (MET) is postulated to be involved in the maintenance and regeneration of the epithelium of female reproductive organs. Here, Ghosh et al. report no definitive evidence of MET in the adult epithelium of oviduct and uterus using in vivo cell lineage tracing and organoids.

The Expression of Anti-Müllerian Hormone Type II Receptor (AMHRII) in Non-Gynecological Solid Tumors Offers Potential for Broad Therapeutic Intervention in Cancer

Simple Summary

Until now, only a few studies have examined the AMHRII expression in tumors. Here, with more than 1000 tumor samples and using several complementary techniques we confirmed AMHRII expression in gynecological cancer and demonstrated AMHRII expression in certain non-gynecological cancers such as colorectal cancers. These findings open the way for new therapeutic approaches targeting AMHRII and emphasize the need to better understand the role of AMH/AMHRII in cancer.

Abstract

The anti-Müllerian hormone (AMH) belongs to the TGF-β family and plays a key role during fetal sexual development. Various reports have described the expression of AMH type II receptor (AMHRII) in human gynecological cancers including ovarian tumors. According to qRT-PCR results confirmed by specific In-Situ Hybridization (ISH) experiments, AMHRII mRNA is expressed in an extremely restricted number of normal tissues. By performing ISH on tissue microarray of solid tumor samples AMHRII mRNA was unexpectedly detected in several non-gynecological primary cancers including lung, breast, head and neck, and colorectal cancers. AMHRII protein expression, evaluated by immunohistochemistry (IHC) was detected in approximately 70% of epithelial ovarian cancers. Using the same IHC protocol on more than 900 frozen samples covering 18 different cancer types we detected AMHRII expression in more than 50% of hepato-carcinomas, colorectal, lung, and renal cancer samples. AMHRII expression was not observed in neuroendocrine lung tumor samples nor in non-Hodgkin lymphoma samples. Complementary analyses by immunofluorescence and flow cytometry confirmed the detection of AMHRII on a panel of ovarian and colorectal cancers displaying comparable expression levels with mean values of 39,000 and 50,000 AMHRII receptors per cell, respectively. Overall, our results suggest that this embryonic receptor could be a suitable target for treating AMHRII-expressing tumors with an anti-AMHRII selective agent such as murlentamab, also named 3C23K or GM102. This potential therapeutic intervention was confirmed in vivo by showing antitumor activity of murlentamab against AMHRII-expressing colorectal cancer and hepatocarcinoma Patient-Derived tumor Xenografts (PDX) models.

Mechanistic Drivers of Müllerian Duct Development and Differentiation Into the Oviduct

The conduits of life; the animal oviducts and human fallopian tubes are of paramount importance for reproduction in amniotes. They connect the ovary with the uterus and are essential for fertility. They provide the appropriate environment for gamete maintenance, fertilization and preimplantation embryonic development. However, serious pathologies, such as ectopic pregnancy, malignancy and severe infections, occur in the oviducts. They can have drastic effects on fertility, and some are life-threatening. Despite the crucial importance of the oviducts in life, relatively little is known about the molecular drivers underpinning the embryonic development of their precursor structures, the Müllerian ducts, and their successive differentiation and maturation. The Müllerian ducts are simple rudimentary tubes comprised of an epithelial lumen surrounded by a mesenchymal layer. They differentiate into most of the adult female reproductive tract (FRT). The earliest sign of Müllerian duct formation is the thickening of the anterior mesonephric coelomic epithelium to form a placode of two distinct progenitor cells. It is proposed that one subset of progenitor cells undergoes partial epithelial-mesenchymal transition (pEMT), differentiating into immature Müllerian luminal cells, and another subset undergoes complete EMT to become Müllerian mesenchymal cells. These cells invaginate and proliferate forming the Müllerian ducts. Subsequently, pEMT would be reversed to generate differentiated epithelial cells lining the fully formed Müllerian lumen. The anterior Müllerian epithelial cells further specialize into the oviduct epithelial subtypes. This review highlights the key established molecular and genetic determinants of the processes involved in Müllerian duct development and the differentiation of its upper segment into oviducts. Furthermore, an extensive genome-wide survey of mouse knockout lines displaying Müllerian or oviduct phenotypes was undertaken. In addition to widely established genetic determinants of Müllerian duct development, our search has identified surprising associations between loss-of-function of several genes and high-penetrance abnormalities in the Müllerian duct and/or oviducts. Remarkably, these associations have not been investigated in any detail. Finally, we discuss future directions for research on Müllerian duct development and oviducts.

Central Regulation of PCOS: Abnormal Neuronal-Reproductive-Metabolic Circuits in PCOS Pathophysiology

Polycystic ovary syndrome (PCOS) is a common reproductive endocrine disease. PCOS patients are characterized by hyperandrogenemia, anovulation, and metabolic dysfunction. Hypothalamus-pituitary-ovary axis imbalance is considered as an important pathophysiology underlying PCOS, indicating that central modulation, especially the abnormal activation of hypothalamic GnRH neurons plays a vital role in PCOS development. Increased GnRH pulse frequency can promote LH secretion, leading to ovarian dysfunction and abnormal sex steroids synthesis. By contrast, peripheral sex steroids can modulate the action of GnRH neurons through a feedback effect, which is impaired in PCOS, thus forming a vicious cycle. Additionally, hypothalamic GnRH neurons not only serve as the final output pathway of central control of reproductive axis, but also as the central connection point where reproductive function and metabolic state inter-regulate with each other. Metabolic factors, such as insulin resistance and obesity in PCOS patients can regulate GnRH neurons activity, and ultimately regulate reproductive function. Besides, gut hormones act on both brain and peripheral organs to modify metabolic state. Gut microbiota disturbance is also related to many metabolic diseases and has been reported to play an essential part in PCOS development. This review concludes with the mechanism of central modulation and the interaction between neuroendocrine factors and reproductive or metabolic disorders in PCOS development. Furthermore, the role of the gut microenvironment as an important part involved in the abnormal neuronal-reproductive-metabolic circuits that contribute to PCOS is discussed, thus offering possible central and peripheral therapeutic targets for PCOS patients.

Lats1 and Lats2 are required for the maintenance of multipotency in the Müllerian duct mesenchyme

WNT signaling plays essential roles in the development and function of the female reproductive tract. Although crosstalk with the Hippo pathway is a key regulator of WNT signaling, whether Hippo itself plays a role in female reproductive biology remains largely unknown. Here, we show that conditional deletion of the key Hippo kinases Lats1 and Lats2 in mouse Müllerian duct mesenchyme cells caused them to adopt the myofibroblast cell fate, resulting in profound reproductive tract developmental defects and sterility. Myofibroblast differentiation was attributed to increased YAP and TAZ expression (but not to altered WNT signaling), leading to the direct transcriptional upregulation of Ctgf and the activation of the myofibroblast genetic program. Müllerian duct mesenchyme cells also became myofibroblasts in male mutant embryos, which impeded the development of the male reproductive tract and resulted in cryptorchidism. The inactivation of Lats1/2 in differentiated uterine stromal cells in vitro did not compromise their ability to decidualize, suggesting that Hippo is dispensable during implantation. We conclude that Hippo signaling is required to suppress the myofibroblast genetic program and maintain multipotency in Müllerian mesenchyme cells.

A tale of two tracts: history, current advances, and future directions of research on sexual differentiation of reproductive tracts†

Alfred Jost's work in the 1940s laid the foundation of the current paradigm of sexual differentiation of reproductive tracts, which contends that testicular hormones drive the male patterning of reproductive tract system whereas the female phenotype arises by default. Once established, the sex-specific reproductive tracts undergo morphogenesis, giving rise to anatomically and functionally distinct tubular organs along the rostral-caudal axis. Impairment of sexual differentiation of reproductive tracts by genetic alteration and environmental exposure are the main causes of disorders of sex development, and infertility at adulthood. This review covers past and present work on sexual differentiation and morphogenesis of reproductive tracts, associated human disorders, and emerging technologies that have made impacts or could radically expand our knowledge in this field.

Defective AMH signaling disrupts GnRH neuron development and function and contributes to hypogonadotropic hypogonadism

Congenital hypogonadotropic hypogonadism (CHH) is a condition characterized by absent puberty and infertility due to gonadotropin releasing hormone (GnRH) deficiency, which is often associated with anosmia (Kallmann syndrome, KS). We identified loss-of-function heterozygous mutations in anti-Müllerian hormone (AMH) and its receptor, AMHR2, in 3% of CHH probands using whole-exome sequencing. We showed that during embryonic development, AMH is expressed in migratory GnRH neurons in both mouse and human fetuses and unconvered a novel function of AMH as a pro-motility factor for GnRH neurons. Pathohistological analysis of Amhr2-deficient mice showed abnormal development of the peripheral olfactory system and defective embryonic migration of the neuroendocrine GnRH cells to the basal forebrain, which results in reduced fertility in adults. Our findings highlight a novel role for AMH in the development and function of GnRH neurons and indicate that AMH signaling insufficiency contributes to the pathogenesis of CHH in humans.

[Mullerian inhibiting substance type II receptor as a potential target for antineoplastic therapy]

The review considers properties of the type II anti-Mullerian hormone receptor (mullerian inhibiting substance receptor type II, MISRII), a transmembrane sensor with its own serine/threonine protein kinase activity, triggering apoptosis of the Mullerian ducts in mammalian embryogenesis and providing formation of the male type reproductive system. According to recent data, MISRII overexpression in the postnatal period is found in cells of a number of ovarian, mammary gland, and prostate tumors, and anti-Mullerian hormone (AMH) has a pro-apoptotic effect on MISRII-positive tumor cells. This fact makes MISRII a potential target for targeted anti-cancer therapy. Treatment based on targeting MISRII seems to be a much more effective alternative to the traditional one and will significantly reduce the drug dose. However, the mechanism of MISRII-AMH interaction is still poorly understood, so the development of new anticancer drugs is complicated. The review analyzes MISRII molecular structure and expression levels in various tissues and cell lines, as well as current understanding of the AMH binding mechanisms and data on the possibility of using MISRII as a target for the action of AMH-based antineoplastic drugs.

Functional Genetic Variation in the Anti-Müllerian Hormone Pathway in Women With Polycystic Ovary Syndrome

CONTEXT

Polycystic ovary syndrome (PCOS) is a highly heritable, common endocrine disorder characterized by hyperandrogenism, irregular menses, and polycystic ovaries. PCOS is often accompanied by elevated levels of anti-Müllerian hormone (AMH). AMH inhibits follicle maturation. AMH also inhibits steroidogenesis through transcriptional repression of CYP17A1. We recently identified 16 rare PCOS-specific pathogenic variants in AMH.

OBJECTIVE

To test whether additional members of the AMH signaling pathway also contribute to the etiology of PCOS.

PARTICIPANTS/DESIGN

Targeted resequencing of coding and regulatory regions of AMH and its specific type 2 receptor, AMHR2, was performed on 608 women affected with PCOS and 142 reproductively normal control women. Prediction tools of deleteriousness and in silico evidence of epigenetic modification were used to prioritize variants for functional evaluation. Dual-luciferase reporter assays and splicing assays were used to measure the impact of genetic variants on function.

RESULTS

We identified 20 additional variants in/near AMH and AMHR2 with significantly reduced signaling activity in in vitro assays. Collectively, from our previous study and as reported herein, we have identified a total of 37 variants with impaired activity in/near AMH and AMHR2 in 41 women affected with PCOS, or 6.7% of our PCOS cohort. Furthermore, no functional variants were observed in the 142 phenotyped controls. The functional variants were significantly associated with PCOS in our cohort of 608 women with PCOS and 142 controls (P = 2.3 × 10-5) and very strongly associated with PCOS relative to a larger non-Finnish European (gnomAD) population-based control cohort (P < 1 × 10-9).

CONCLUSION

The AMH signaling cascade plays an important role in PCOS etiology.

A gene regulatory network for Müllerian duct regression

Mammalian embryos initially develop progenitor tissues for both male and female reproductive tract organs, known as the Wolffian ducts and the Müllerian ducts, respectively. Ultimately, each individual develops a single set of male or female reproductive tract organs. Therefore, an essential step for sex differentiation is the regression of one duct and growth and differentiation of the other duct. In males, this requires Müllerian duct regression and Wolffian duct growth and differentiation. Müllerian duct regression is induced by the expression of Amh, encoding anti-Müllerian hormone, from the fetal testes. Subsequently, receptor-mediated signal transduction in mesenchymal cells surrounding the Müllerian duct epithelium leads to duct elimination. The genes that induce Amh transcription and the downstream signaling that results from Amh activity form a pathway. However, the molecular details of this pathway are currently unknown. A set of essential genes for AMH pathway function has been identified. More recently, transcriptome analysis of male and female Müllerian duct mesenchyme at an initial stage of regression has identified new genes that may mediate elimination of the Müllerian system. The evidence taken together can be used to generate an initial gene regulatory network describing the Amh pathway for Müllerian duct regression. An Amh gene regulatory network will be a useful tool to study Müllerian duct regression, sex differentiation, and its relationship to environmental influences.

CD34+KLF4+ Stromal Stem Cells Contribute to Endometrial Regeneration and Repair

The regenerative capacity of the human endometrium requires a population of local stem cells. However, the phenotypes, locations, and origin of these cells are still unknown. In a mouse menstruation model, uterine stromal SM22α+-derived CD34+KLF4+ stem cells are activated and integrate into the regeneration area, where they differentiate and incorporate into the endometrial epithelium; this process is correlated with enhanced protein SUMOylation in CD34+KLF4+ cells. Mice with a stromal SM22α-specific SENP1 deletion (SENP1smKO) exhibit accelerated endometrial repair in the regeneration model and develop spontaneous uterine hyperplasia. Mechanistic studies suggest that SENP1 deletion induces SUMOylation of ERα, which augments ERα transcriptional activity and proliferative signaling in SM22α+CD34+KLF4+ cells. These cells then transdifferentiate to the endometrial epithelium. Our study reveals that CD34+KLF4+ stromal-resident stem cells directly contribute to endometrial regeneration, which is regulated through SENP1-mediated ERα suppression.

Müllerian inhibiting substance/anti-Müllerian hormone type II receptor protein and mRNA expression in the healthy and cancerous endometria

Müllerian inhibiting substance/anti-Müllerian hormone (MIS/AMH) is a regulator of the female reproductive system, an indicator of ovarian reserve and a growth inhibitor of Müllerian duct-derived tumors in vivo and in vitro. The objective of the present study was to analyze MIS/AMH type II receptor (MIS/AMHRII) protein and mRNA expression in healthy human endometria compared with patients with endometrial hyperplasia and endometrial cancer, providing a foundation for MIS/AMH as a biological modifier for treatment of endometrial hyperplasia and endometrial cancer. The present study included healthy endometrial tissues (n=20), simple endometrial hyperplasia tissues without atypia (n=17), complex endometrial hyperplasia tissues without atypia (n=24) and endometrial cancer tissues (n=8). The location and variation of MIS/AMHRII protein expression was observed by immunohistochemistry. The expression was graded by two pathologists and was categorized as follows: Negative, weakly positive, moderately positive or strongly positive. Reverse transcription-quantitative polymerase chain reaction was used to quantify MIS/AMHRII mRNA expression. The expression of MIS/AMHRII protein was observed in the cytoplasm of healthy human endometria, endometrial hyperplasia and endometrial cancer cells. The frequency of MIS/AMHRII protein expression was 20.22±10.35% in the proliferative phase of the healthy endometrium and 24.09±11.73% in the secretory phase of the healthy endometrium. However, no differences were observed in the menstrual cycle phases. The frequency was 54.50±16.59% in endometrial hyperplasia without atypia, 55.10±15.87% in endometrial hyperplasia with atypia and 73.88±15.70% in endometrial cancer, indicating that expression was enhanced as the disease progressed from healthy to malignant status. In endometrial hyperplasia, MIS/AMHRII protein expression was significantly associated with histological complexity compared with atypia status. The present study demonstrated that MIS/AMHRII is present in healthy endometria, endometrial hyperplasia and endometrial cancer. The low expression frequency of MIS/AMHRII was not significantly different among normal endometrial tissues, however, the protein expression was elevated in endometrial hyperplasia and endometrial cancer. These findings indicated that the study of bioactive MIS/AMH, as a possible treatment for tumors expressing the MIS/AMH receptor, is essential.

Ovarian activity regulation by anti-Müllerian hormone in early stages of human female life, an overview

The present study aimed at describing the anti-Müllerian hormone (AMH), with special focus on molecular background for ovarian activity, in particular the role AMH plays in sex determination and gonadogenesis process in early stages of prenatal life and folliculogenesis in postnatal life. It is a review of the literature currently indexed and abstracted in MEDLINE, SCOPUS and Google Scholars. The process of sex determination and gonad differentiation occurring during embryogenesis was discussed along with underlying molecular mechanisms. In the postnatal life the impact of AMH on the process of folliculogenesis was described. Clinical use of recent findings was shown as well. Genetic studies and molecular analyses have demonstrated that AMH is highly conservative, indicating its significance in reproductive process on the background of evolutionary processes.

Expression of Müllerian-Inhibiting Substance/Anti-Müllerian Hormone Type II Receptor in the Human Theca Cells

CONTEXT

Müllerian-inhibiting substance/anti-Müllerian hormone (MIS/AMH) is produced in the ovarian granulosa cells, and it is believed to inhibit ovarian folliculogenesis and steroidogenesis in women of reproductive age.

OBJECTIVE

To investigate the expression of MIS/AMH type II receptor (MISRII/AMHRII) that binds MIS/AMH in the ovaries of reproductive-age women; to identify the exact targets of MIS/AMH.

DESIGN

Laboratory study using human ovarian tissue.

SETTING

University hospital.

PATIENTS

Tissue samples from 25 patients who had undergone ovarian surgery.

INTERVENTIONS

The segregation of ovarian granulosa and theca cells by laser microdissection was followed by RT-PCR, analyzing MISRII/AMHRII mRNA expression. Afterward, in situ hybridization and immunohistochemistry were performed to determine the localization of MISRII/AMHRII mRNA and protein expression.

MAIN OUTCOME MEASURES

MISRII/AMHRII mRNA expression by RT-PCR, in situ hybridization, and immunohistochemistry.

RESULTS

MISRII/AMHRII were expressed in granulosa and theca cells of preantral and antral follicles. The granulosa cells showed stronger MISRII/AMHRII expression than theca cells. MISRII/AMHRII mRNA staining of granulosa and theca cells in large antral follicles, early atretic follicles, and corpus luteum waned but were still detected weakly, showing higher expression in theca cells than in granulosa cells. However, MISRII/AMHRII protein in the granulosa layer of the atretic follicle and corpus luteum could not be assessed.

CONCLUSIONS

As MISRII/AMHRII is expressed in both granulosa and theca cells, this indicates that MIS/AMH, produced in the granulosa cells, is active in the theca cells as well. MIS/AMH is most likely actively involved not only in the autocrine and endocrine processes but also in the paracrine processes involving theca cells.

Genomic heritability and genome-wide association analysis of anti-Müllerian hormone in Holstein dairy heifers

Anti-Müllerian hormone (AMH) is an ovarian growth factor that plays an important role in regulation of ovarian follicle growth. The objectives of this study were to estimate the genomic heritability of AMH and identify genomic regions associated with AMH production in a genome-wide association (GWA) analysis. Concentrations of AMH were determined in 2,905 dairy Holstein heifers genotyped using the Zoetis medium density panel (Zoetis Inclusions, Kalamazoo, MI) with 54,519 single nucleotide polymorphism (SNP) markers remaining after standard genotype quality control edits. A linear mixed model was used to model the random effects of sampling day and genomics on the logarithm of AMH. The genomic heritability (± standard error of the mean) of AMH was estimated to be 0.36 ± 0.03. Our GWA analysis inferred significant associations between AMH and 11 SNP markers on chromosome 11 and 1 SNP marker on chromosome 20. Annotated genes with significant associations were identified using the Ensembl genome database (version 88) of the cow genome (version UMD 3.1; https://www.ensembl.org/biomart). Gene set enrichment analysis revealed that 2 gene ontology (GO) terms were significantly enriched in the list of candidate genes: G-protein coupled receptor signaling pathway (GO:0007186) and the detection of chemical stimulus involved in sensory perception (GO:0050907). The estimated high heritability and previously established associations between AMH and ovarian follicular reserve, fertility, longevity, and superovulatory response in cattle implies that AMH could be used as a biomarker for genetic improvement of reproductive potential.

Primary Immunoprevention of Epithelial Ovarian Carcinoma by Vaccination against the Extracellular Domain of Anti-Müllerian Hormone Receptor II

Epithelial ovarian carcinoma (EOC) is the most prevalent form of ovarian cancer in the United States, representing approximately 85% of all cases and causing more deaths than any other gynecologic malignancy. We propose that optimized control of EOC requires the incorporation of a vaccine capable of inducing safe and effective preemptive immunity in cancer-free women. In addition, we hypothesize that ovarian-specific self-proteins that are "retired" from autoimmune-inducing expression levels as ovaries age but are expressed at high levels in emerging EOC may serve as vaccine targets for mediating safe and effective primary immunoprevention. Here, we show that expression of the extracellular domain of anti-Müllerian hormone receptor II (AMHR2-ED) in normal tissues is confined exclusively to the human ovary, drops to nonautoimmune inducing levels in postmenopausal ovaries, and is at high levels in approximately 90% of human EOC. We found that AMHR2-ED vaccination significantly inhibits growth of murine EOC and enhances overall survival without inducing oophoritis in aged female mice. The observed inhibition of EOC growth was mediated substantially by induction of AMHR2-ED-specific IgG antibodies that agonize receptor signaling of a Bax/caspase-3-dependent proapoptotic cascade. Our results indicate that AMHR2-ED vaccination may be particularly useful in providing safe and effective preemptive immunity against EOC in women at high genetic or familial risk who have the greatest need for a preventive vaccine and ultimately in cancer-free postmenopausal women who account for 75% of all EOC cases. Cancer Prev Res; 10(11); 612-24. ©2017 AACRSee related editorial by Shoemaker et al., p. 607.

The mechanisms underlying the effects of AMH on Müllerian duct regression in male mice

Anti-Müllerian hormone (AMH) produced in the developing testis induces the regression of the Müllerian duct, which develops into the oviducts, uterus and upper vagina. In our true hermaphrodite mouse with an ovary on one side and a testis on the other (O/T), the oviduct and uterus are present only on the ovary side, and nothing derived from the Müllerian duct is present on the testis side. Here, we investigate the mechanism underlying the unilateral Müllerian duct regression and the mode of AMH signaling, by performing immunohistology, Western blotting, and organ culture analyses. The histological analysis revealed that during the start of the Müllerian duct regression, the duct in the O/T mice was clearly regressed on the AMH-positive testis side compared to the AMH-negative ovary side. The immunohistochemistry showed a diffuse immunoreaction of AMH in the interstitium surrounding the testis cord and boundary region between the testis and mesonephros, especially in the cranial portion. Western blotting revealed that the amount of AMH in the cranial half of the mesonephros was larger than that in the caudal half. AMH injected into the gonads in organ culture induced the regression of the Müllerian duct via the interstitium of the organ. These results suggest that AMH acts on the Müllerian duct in male mice by exuding into the interstitium surrounding the testis cord and infiltrating through the cranial region from the testis to the mesonephros.

Specific deletion of LKB1/Stk11 in the Müllerian duct mesenchyme drives hyperplasia of the periurethral stroma and tumorigenesis in male mice

Nearly all older men will experience lower urinary tract symptoms associated with benign prostatic hyperplasia (BPH), the etiology of which is not well understood. We have generated Stk11^CKO mice by conditional deletion of the liver kinase B1 (LKB1) tumor suppressor gene, Stk11 (serine threonine kinase 11), in the fetal Müllerian duct mesenchyme (MDM), the caudal remnant of which is thought to be assimilated by the urogenital sinus primordial mesenchyme in males during fetal development. We show that MDM cells contribute to the postnatal stromal cells at the dorsal aspect of the prostatic urethra by lineage tracing. The Stk11^CKO mice develop prostatic hyperplasia with bladder outlet obstruction, most likely because of stromal expansion. The stromal areas from prostates of Stk11^CKO mice, with or without significant expansion, were estrogen receptor positive, which is consistent with both MD mesenchyme-derived cells and the purported importance of estrogen receptors in BPH development and/or progression. In some cases, stromal hyperplasia was admixed with epithelial metaplasia, sometimes with keratin pearls, consistent with squamous cell carcinomas. Mice with conditional deletion of both Stk11 and Pten developed similar features as the Stk11^CKO mice, but at a highly accelerated rate, often within the first few months after birth. Western blot analyses showed that the loss of LKB1 and phosphatase and tensin homolog deleted on chromosome 10 (PTEN) induces activation of the phospho-5' adenosine monophosphate-activated protein kinase and phospho-AKT serine/threonine kinase 1 signaling pathways, as well as increased total and active β-catenin. These results suggest that activation of these signaling pathways can induce hyperplasia of the MD stroma, which could play a significant role in the etiology of human BPH.

AMH/MIS as a contraceptive that protects the ovarian reserve during chemotherapy

The ovarian reserve represents the stock of quiescent primordial follicles in the ovary which is gradually depleted during a woman's reproductive lifespan, resulting in menopause. Müllerian inhibiting substance (MIS) (or anti-Müllerian hormone/AMH), which is produced by granulosa cells of growing follicles, has been proposed as a negative regulator of primordial follicle activation. Here we show that long-term parenteral administration of superphysiological doses of MIS, using either an adeno-associated virus serotype 9 (AAV9) gene therapy vector or recombinant protein, resulted in a complete arrest of folliculogenesis in mice. The ovaries of MIS-treated mice were smaller than those in controls and did not contain growing follicles but retained a normal ovarian reserve. When mice treated with AAV9/MIS were paired with male breeders, they exhibited complete and permanent contraception for their entire reproductive lifespan, disrupted vaginal cycling, and hypergonadotropic hypogonadism. However, when ovaries from AAV9-MIS-treated mice were transplanted orthotopically into normal recipient mice, or when treatment with the protein was discontinued, folliculogenesis resumed, suggesting reversibility. One of the important causes of primary ovarian insufficiency is chemotherapy-induced primordial follicle depletion, which has been proposed to be mediated in part by increased activation. To test the hypothesis that MIS could prevent chemotherapy-induced overactivation, mice were given carboplatin, doxorubicin, or cyclophosphamide and were cotreated with AAV9-MIS, recombinant MIS protein, or vehicle controls. We found significantly more primordial follicles in MIS-treated animals than in controls. Thus treatment with MIS may provide a method of contraception with the unique characteristic of blocking primordial follicle activation that could be exploited to prevent the primary ovarian insufficiency often associated with chemotherapy.

Structural Biology and Evolution of the TGF-β Family

We review the evolution and structure of members of the transforming growth factor β (TGF-β) family, antagonistic or agonistic modulators, and receptors that regulate TGF-β signaling in extracellular environments. The growth factor (GF) domain common to all family members and many of their antagonists evolved from a common cystine knot growth factor (CKGF) domain. The CKGF superfamily comprises six distinct families in primitive metazoans, including the TGF-β and Dan families. Compared with Wnt/Frizzled and Notch/Delta families that also specify body axes, cell fate, tissues, and other families that contain CKGF domains that evolved in parallel, the TGF-β family was the most fruitful in evolution. Complexes between the prodomains and GFs of the TGF-β family suggest a new paradigm for regulating GF release by conversion from closed- to open-arm procomplex conformations. Ternary complexes of the final step in extracellular signaling show how TGF-β GF dimers bind type I and type II receptors on the cell surface, and enable understanding of much of the specificity and promiscuity in extracellular signaling. However, structures suggest that when GFs bind repulsive guidance molecule (RGM) family coreceptors, type I receptors do not bind until reaching an intracellular, membrane-enveloped compartment, blurring the line between extra- and intracellular signaling. Modulator protein structures show how structurally diverse antagonists including follistatins, noggin, and members of the chordin family bind GFs to regulate signaling; complexes with the Dan family remain elusive. Much work is needed to understand how these molecular components assemble to form signaling hubs in extracellular environments in vivo.

Expressional changes of AMH signaling system in the quail testis induced by photoperiod

Gonadal sex differentiation proceeds by the interplay of various genes including the transcription factors and secretory factors in a complex network. The sex-differentiating genes are expressed not only during early sex differentiation but also throughout the gonadal development and even in the adult gonads. In addition, the evidence that they actually function in the adult gonads have been accumulated from the studies using the conditional knockout mice. However, many previous studies were focused on one single gene though those genes function in a network. In this study, the expressions of various sex-differentiating genes were analyzed simultaneously in the adult testis of the Japanese quail (Coturnix japonica), whose testicular functions are dramatically changed by altering the photoperiod, to elucidate the roles of them in the adult gonad. Anti-Müllerian hormone (AMH) was significantly upregulated in the regressed testis induced by the short-day condition. The expressions of the transcription factors that promoteAMHexpression in mammals (SF1,SOX9,WT1andGATA4) were also increased in the regressed testis. Moreover, AMH receptor (AMHR2) showed similar expression pattern to its ligand. We also analyzed the expressions of other transforming growth factor beta (TGFB) superfamily members and their receptors. The expressions of the ligands and receptors of TGFB family, and follistatin and betaglycan in addition to inhibin subunits were increased in the regressed testis. These results suggest that AMH is involved in the adult testicular functions of the Japanese quail together with other TGFB superfamily members.

Anti-Müllerian hormone is produced heterogeneously in primate preantral follicles and is a potential biomarker for follicle growth and oocyte maturation in vitro

PURPOSE

The main goals of this study were to investigate the expression of anti-Müllerian hormone (AMH) and its receptor (AMHR2) during follicular development in primates, and to evaluate the potential of AMH as a biomarker for follicle growth and oocyte maturation in vitro.

METHODS

The mRNA and protein expression of AMH and AMHR2 were determined using isolated follicles and ovarian sections from rhesus macaques (n = 4) by real-time PCR and immunohistochemistry, respectively. Isolated secondary follicles were cultured individually. Follicle growth and media AMH concentrations were assessed by ELISA. The mRNA expression profiles, obtained from RNA sequencing, of in vitro- and in vivo-developed antral follicles were compared. Secondary follicles from additional animals (n = 35) were cultured. Follicle growth, oocyte maturation, and media AMH concentrations were evaluated for forecasting follicular development in vitro by AMH levels.

RESULTS

AMH immunostaining was heterogeneous in the population of preantral follicles that were also stained for AMHR2. The mRNA expression profiles were comparable between in vivo- and in vitro-developed follicles. AMH levels produced by growing follicles were higher than those of nongrowing follicles in culture. With a cutoff value of 1.40 ng/ml, 85 % of nongrowing follicles could be identified while eliminating only 5 % of growing follicles. Growing follicles that generated metaphase II-stage oocytes secreted greater amounts of AMH than did those yielding immature germinal vesicle-stage oocytes.

CONCLUSIONS

AMH, co-expressed with AMHR2, was produced heterogeneously by preantral follicles in macaques with levels correlated positively with follicle growth and oocyte maturation. AMH may serve as a biomarker for primate follicular development in vitro.

The ovarian response to standard gonadotropin stimulation is influenced by AMHRII genotypes

The aim of the current study was to explore whether anti-Müllerian hormone receptor II (AMHRII) genetic variants influence the hormonal profile and the ovarian response to standard gonadotropin stimulation of women undergoing medically assisted reproduction. Three hundred in vitro fertilization or intracytoplasmic sperm injection patients constituted the study population, while 300 women with at least one spontaneous pregnancy participated as controls. The follicle-stimulating hormone (FSH), luteinizing hormone (LH), estradiol (E₂) and AMH levels were determined at the third day of the menstrual cycle. AMHRII 10A > G (rs11170555), 1749C > T (rs2071558) and -482A > G (rs2002555) polymorphisms were genotyped. The follicle and oocyte numbers, the follicle size and the clinical pregnancies were recorded. Regarding the AMHRII 1749C > T polymorphism, 1749CT women presented with higher total follicle and small follicle numbers compared to 1749CC women (p = 0.04 and p = 0.01, respectively). Whereas, as concerns the -482A > G polymorphism, -482AG women were characterized by higher total follicle and small follicle numbers comparing with -482AA women (p = 0.07 and p = 0.004, respectively). Finally, -482AG women presented with increased FSH levels compared to -482AA women (p < 0.05). However, no associations of AMHRII gene polymorphisms with serum AMH levels or clinical pregnancy rates were observed. AMHRII 1749C > T and -482A > G genetic variants were associated with the ovarian response to standard gonadotropin stimulation, affecting mainly the follicular growth.

The Discovery and Early Days of TGF-β: A Historical Perspective

Transforming growth factors (TGFs) were discovered as activities that were secreted by cancer cells, and later by normal cells, and had the ability to phenotypically and reversibly transform immortalized fibroblasts. TGF-β distinguished itself from TGF-α because it did not bind to the same epidermal growth factor (EGF) receptor as TGF-α and, therefore, acted through different cell-surface receptors and signaling mediators. This review summarizes the discovery of TGF-β, the early developments in its molecular and biological characterization with its many biological activities in different cell and tissue contexts and its roles in disease, the realization that there is a family of secreted TGF-β-related proteins with many differentiation functions in development and activities in normal cell and tissue physiology, and the subsequent identification and characterization of the receptors and effectors that mediate TGF-β family signaling responses.

Anti-Müllerian hormone (AMH) receptor type II expression and AMH activity in bovine granulosa cells

Anti-Müllerian hormone (AMH) produced by granulosa cells has previously been proposed to play a role in regulating granulosa cell differentiation and follicle selection. Although AMH receptor type II (AMHR2) dimerizes with a type I receptor to initiate AMH signaling, little is known about the regulation of AMHR2 expression in bovine granulosa cells and the role of AMH in follicle development. The primary objectives of this study were to: (1) characterize AMHR2 expression in granulosa cells during follicle development; (2) identify factors that regulate AMHR2 mRNA expression in granulosa cells; and (3) examine the role of AMH signaling in granulosa cell differentiation and proliferation. Bovine granulosa cells were isolated from 5- to 8-mm follicles before selection and deviation, as well as from 9- to 12-mm and 13- to 24-mm follicles after selection. Analyses revealed that expression of AMHR2 was greater in 5- to 8-mm follicles compared with 13- to 24-mm follicles (P < 0.05). Granulosa cells treated with bone morphogenetic protein 6 (BMP6) or BMP15, but not BMP2, significantly increased AMHR2 expression when compared with control cultured cells (P < 0.05). In addition, expression of AMH was greater in granulosa cells cultured with BMP2, BMP6, or BMP15 when compared with controls (P < 0.05). Finally, treatment with recombinant human AMH, in vitro, inhibited CYP19A1 expression in a dose-related (10-100 ng/mL) fashion, and reduced granulosa cell proliferation at 48 and 72 hours (P < 0.05). Results from these studies indicate that AMH signaling plays a role in both regulating granulosa cell proliferation and preventing granulosa cells from 5- to 8-mm follicles from undergoing premature differentiation before follicle selection.

Sex-dependent expression of anti-Müllerian hormone (amh) and amh receptor 2 during sex organ differentiation and characterization of the Müllerian duct development in Xenopus tropicalis

Amphibian gonadal differentiation involves the action of sex steroids. Recent research indicates that the anti-Müllerian hormone (AMH) is involved in testicular development in some lower vertebrate species. For amphibians there is a lack of data on ontogenetic expression of the AMH receptor AMHR2/amhr2 and of progesterone receptors (PGRS/pgrs). Here we expand the knowledge on amphibian sex differentiation by characterizing ontogenetic mRNA levels of amh, amhr2, intracellular and membrane pgrs (ipgr and mpgr beta) and cytochrome P450 19a1 (cyp19a1) (ovarian marker) in the urogenital complex of the model species Xenopus (Silurana) tropicalis. Furthermore, we characterized the ontogenetic development of the Müllerian ducts (precursors of the female reproductive tract) histologically. The developmental period investigated spanned from beginning of gonadal differentiation, Nieuwkoop and Faber (NF) stage 51, to 4weeks post-metamorphosis. The Müllerian ducts were first observed at NF 64 in both sexes. Male-enhanced amh mRNA levels from NF 53/54 to 6days post-metamorphosis and female-enhanced cyp19a1 levels from NF 53 to 4weeks post-metamorphosis were noted. The sexually dimorphic mRNA level profile was more distinct for amh than for cyp19a1. The pgrs mRNA levels increased over the studied period and showed no sex differences. At later developmental stages, the amhr2 mRNA level was increased in putative females compared with males. Our findings suggest that AMH has a role in gonadal differentiation in X. tropicalis. We propose relative gonadal amh mRNA level as a testicular marker during early gonadal development in amphibians.

Novel role for anti-Müllerian hormone in the regulation of GnRH neuron excitability and hormone secretion

Anti-Müllerian hormone (AMH) plays crucial roles in sexual differentiation and gonadal functions. However, the possible extragonadal effects of AMH on the hypothalamic–pituitary–gonadal axis remain unexplored. Here we demonstrate that a significant subset of GnRH neurons both in mice and humans express the AMH receptor, and that AMH potently activates the GnRH neuron firing in mice. Combining in vivo and in vitro experiments, we show that AMH increases GnRH-dependent LH pulsatility and secretion, supporting a central action of AMH on GnRH neurons. Increased LH pulsatility is an important pathophysiological feature in many cases of polycystic ovary syndrome (PCOS), the most common cause of female infertility, in which circulating AMH levels are also often elevated. However, the origin of this dysregulation remains unknown. Our findings raise the intriguing hypothesis that AMH-dependent regulation of GnRH release could be involved in the pathophysiology of fertility and could hold therapeutic potential for treating PCOS.

Anti-Müllerian hormone (AMH) plays a role in sexual differentiation and gonadal function, but extra-gonadal effects of AMH are not known. Here Cimino et al. show that AMH activates a subset of gonadotrophin-releasing hormone (GnRH)-releasing neurons, contributing to luteinizing hormone secretion from the pituitary gland.

Molecular cloning and characterization of amh and dax1 genes and their expression during sex inversion in rice-field eel Monopterus albus

The full-length cDNAs of amh and dax1 in the hermaphrodite, rice-field eel (Monopterus albus), were cloned and characterized in this study. Multiple sequence alignment revealed Dax1 was well conserved among vertebrates, whereas Amh had a low degree of similarity between different vertebrates. Their expression profiles in gonads during the course of sex inversion and tissues were investigated. The tissue distribution indicated amh was expressed mostly in gonads and was scarcely detectable in other tissues, whereas the expression of dax1 was widespread among the different tissues, especially liver and gonads. amh was scarcely detectable in ovaries whereas it was abundantly expressed in both ovotestis and testis. By contrast, dax1 was highly expressed in ovaries, especially in ♀IV (ovaries in IV stage), but it was decreased significantly in ♀/♂I (ovotestis in I stage). Its expression was increased again in ♀/♂III (ovotestis in III stage), and then decreased to a low level in testis. These significant different expression patterns of amh and dax1 suggest the increase of amh expression and the decline of dax1 expression are important for the activation of testis development, and the high level of amh and a low level of dax1 expression are necessary for maintenance of testis function.

Regulation of Murine Ovarian Epithelial Carcinoma by Vaccination against the Cytoplasmic Domain of Anti-Müllerian Hormone Receptor II

Anti-Müllerian hormone receptor, type II (AMHR2), is a differentiation protein expressed in 90% of primary epithelial ovarian carcinomas (EOCs), the most deadly gynecologic malignancy. We propose that AMHR2 may serve as a useful target for vaccination against EOC. To this end, we generated the recombinant 399-amino acid cytoplasmic domain of mouse AMHR2 (AMHR2-CD) and tested its efficacy as a vaccine target in inhibiting growth of the ID8 transplantable EOC cell line in C57BL/6 mice and in preventing growth of autochthonous EOCs that occur spontaneously in transgenic mice. We found that AMHR2-CD immunization of C57BL/6 females induced a prominent antigen-specific proinflammatory CD4+ T cell response that resulted in a mild transient autoimmune oophoritis that resolved rapidly with no detectable lingering adverse effects on ovarian function. AMHR2-CD vaccination significantly inhibited ID8 tumor growth when administered either prophylactically or therapeutically, and protection against EOC growth was passively transferred into naive recipients with AMHR2-CD-primed CD4+ T cells but not with primed B cells. In addition, prophylactic AMHR2-CD vaccination of TgMISIIR-TAg transgenic mice significantly inhibited growth of autochthonous EOCs and provided a 41.7% increase in mean overall survival. We conclude that AMHR2-CD vaccination provides effective immunotherapy of EOC with relatively benign autoimmune complications.

Mechanisms of BMP-Receptor Interaction and Activation

Bone morphogenetic proteins (BMPs), together with the eponymous transforming growth factor (TGF) β and the Activins form the TGFβ superfamily of ligands. This protein family comprises more than 30 structurally highly related proteins, which determine formation, maintenance, and regeneration of tissues and organs. Their importance for the development of multicellular organisms is evident from their existence in all vertebrates as well as nonvertebrate animals. From their highly specific functions in vivo either a strict relation between a particular ligand and its cognate cellular receptor and/or a stringent regulation to define a distinct temperospatial expression pattern for the various ligands and receptor is expected. However, only a limited number of receptors are found to serve a large number of ligands thus implicating highly promiscuous ligand-receptor interactions instead. Since in tissues a multitude of ligands are often found, which signal via a highly overlapping set of receptors, this raises the question how such promiscuous interactions between different ligands and their receptors can generate concerted and highly specific cellular signals required during embryonic development and tissue homeostasis.

Müllerian inhibiting substance/anti-Müllerian hormone: A novel treatment for gynecologic tumors

Müllerian inhibiting substance (MIS), also called anti-Müllerian hormone (AMH), is a member of the transforming growth factor-β super-family of growth and differentiation response modifiers. It is produced in immature Sertoli cells in male embryos and binds to MIS/AMH receptors in primordial Müllerian ducts to cause regression of female reproductive structures that are the precursors to the fallopian tubes, the surface epithelium of the ovaries, the uterus, the cervix, and the upper third of the vagina. Because most gynecologic tumors originate from Müllerian duct-derived tissues, and since MIS/AMH causes regression of the Müllerian duct in male embryos, it is expected to inhibit the growth of gynecologic tumors. Purified recombinant human MIS/AMH causes growth inhibition of epithelial ovarian cancer cells and cell lines in vitro and in vitro via MIS receptor-mediated mechanism. Furthermore, several lines of evidence suggest that MIS/AMH inhibits proliferation in tissues and cell lines of other MIS/AMH receptor-expressing gynecologic tumors such as cervical, endometrial, breast, and in endometriosis as well. These findings indicate that bioactive MIS/AMH recombinant protein should be tested in patients against tumors expressing the MIS/AMH receptor complex, perhaps beginning with ovarian cancer because it has the worst prognosis. The molecular tools to identify MIS/AMH receptor expressing ovarian and other cancers are in place, thus, it is possible to select patients for treatment. An MIS/AMH ELISA exists to follow administered doses of MIS/AMH, as well. Clinical trials await the production of sufficient supplies of qualified recombinant human MIS/AMH for this purpose.

Identification, expression, and regulation of anti-Müllerian hormone type-II receptor in the embryonic chicken gonad

Anti-Müllerian hormone (AMH) signaling is required for proper development of the urogenital system in vertebrates. In male mammals, AMH is responsible for regressing the Müllerian ducts, which otherwise develop into the fallopian tubes, oviducts, and upper vagina of the female reproductive tract. This role is highly conserved across higher vertebrates. However, AMH is required for testis development in fish species that lack Müllerian ducts, implying that AMH signaling has broader roles in other vertebrates. AMH signals through two serine/threonine kinase receptors. The primary AMH receptor, AMH receptor type-II (AMHR2), recruits the type I receptor, which transduces the signal intracellularly. To enhance our understanding of AMH signaling and the potential role of AMH in gonadal sex differentiation, we cloned chicken AMHR2 cDNA and examined its expression profile during gonadal sex differentiation. AMHR2 is expressed in the gonads and Müllerian ducts of both sexes but is more strongly expressed in males after the onset of gonadal sex differentiation. In the testes, the AMHR2 protein colocalizes with AMH, within Sertoli cells of the testis cords. AMHR2 protein expression is up-regulated in female embryos treated with the estrogen synthesis inhibitor fadrozole. Conversely, knockdown of the key testis gene DMRT1 leads to disruption of AMHR2 expression in the developing seminiferous cords of males. These results indicate that AMHR2 is developmentally regulated during testicular differentiation in the chicken embryo. AMH signaling may be important for gonadal differentiation in addition to Müllerian duct regression in birds.

Role of anti-Müllerian hormone and bone morphogenetic proteins in the regulation of FSH sensitivity

The ovary is under control of the hypothalamus and pituitary through the glycoprotein hormones LH and FSH. These hormones undergo a cyclic variation which results in the selection of the species-specific number of follicles that will ovulate during the cycle. Where LH is the main ovulatory hormone and regulator of corpus luteum function, FSH plays an essential role in the cyclic recruitment of the follicles. Within the microenvironment of the ovary, growth factors affect this dominant control of FSH by regulating the FSH sensitivity of individual follicles. In this review we discuss the role of anti-Müllerian hormone (AMH) and bone morphogenetic proteins (BMPs) in this process.

The effects of isotretinoin on the ovarian reserve of females with acne

There are some side effects of isotretinoin in many organs. However, a study investigating the effects of isotretinoin on the human ovarian reserve has not been reported previously. The study was conducted to investigate possible effects of isotretinoin on ovarian reserve. Serum anti-Müllerian hormone (AMH) levels were measured at the beginning and at the end of isotretinoin treatment in 22 patients with acne and in 22 women without. The mean AMH level before treatment was 5.77 ng/mL in the study group and 3.79 ng/mL in the control group (p = 0.008). Following treatment, the mean AMH level was 4.69 ng/mL in the study group. This mean AMH level after treatment was statistically lower than the AMH level before treatment (p = 0.012). There was no significant difference between the mean AMH level at the end of treatment and that of the control group (p = 0.20). The high level of pre-treatment AMH levels could be an evidence of hyperandrogenism in women with acne, even if they are not identified as having polycystic ovary syndrome (PCOS) or hyperandrogenism. Decrease in AMH levels following exposure to isotretinoin may suggest that it has a detrimental effect on the ovaries.

Induction of WNT inhibitory factor 1 expression by Müllerian inhibiting substance/antiMullerian hormone in the Müllerian duct mesenchyme is linked to Müllerian duct regression

A key event during mammalian sexual development is regression of the Müllerian ducts (MDs) in the bipotential urogenital ridges (UGRs) of fetal males, which is caused by the expression of Müllerian inhibiting substance (MIS) in the Sertoli cells of the differentiating testes. The paracrine signaling mechanisms involved in MD regression are not completely understood, particularly since the receptor for MIS, MISR2, is expressed in the mesenchyme surrounding the MD, but regression occurs in both the epithelium and mesenchyme. Microarray analysis comparing MIS signaling competent and Misr2 knockout embryonic UGRs was performed to identify secreted factors that might be important for MIS-mediated regression of the MD. A seven-fold increase in the expression of Wif1, an inhibitor of WNT/β-catenin signaling, was observed in the Misr2-expressing UGRs. Whole mount in situ hybridization of Wif1 revealed a spatial and temporal pattern of expression consistent with Misr2 during the window of MD regression in the mesenchyme surrounding the MD epithelium that was absent in both female UGRs and UGRs knocked out for Misr2. Knockdown of Wif1 expression in male UGRs by Wif1-specific siRNAs beginning on embryonic day 13.5 resulted in MD retention in an organ culture assay, and exposure of female UGRs to added recombinant human MIS induced Wif1 expression in the MD mesenchyme. Knockdown of Wif1 led to increased expression of β-catenin and its downstream targets TCF1/LEF1 in the MD mesenchyme and to decreased apoptosis, resulting in partial to complete retention of the MD. These results strongly suggest that WIF1 secretion by the MD mesenchyme plays a role in MD regression in fetal males.