SOX9 and SF1 are involved in cyclic AMP-mediated upregulation of anti-Mullerian gene expression in the testicular prepubertal Sertoli cell line SMAT1

Anti-Müllerian hormone, testicular descent and cryptorchidism

Anti-Müllerian hormone (AMH) is a Sertoli cell-secreted glycoprotein involved in male fetal sex differentiation: it provokes the regression of Müllerian ducts, which otherwise give rise to the Fallopian tubes, the uterus and the upper part of the vagina. In the first trimester of fetal life, AMH is expressed independently of gonadotropins, whereas from the second trimester onwards AMH testicular production is stimulated by FSH and oestrogens; at puberty, AMH expression is inhibited by androgens. AMH has also been suggested to participate in testicular descent during fetal life, but its role remains unclear. Serum AMH is a well-recognized biomarker of testicular function from birth to the first stages of puberty. Especially in boys with nonpalpable gonads, serum AMH is the most useful marker of the existence of testicular tissue. In boys with cryptorchidism, serum AMH levels reflect the mass of functional Sertoli cells: they are lower in patients with bilateral than in those with unilateral cryptorchidism. Interestingly, serum AMH increases after testis relocation to the scrotum, suggesting that the ectopic position result in testicular dysfunction, which may be at least partially reversible. In boys with cryptorchidism associated with micropenis, low AMH and FSH are indicative of central hypogonadism, and serum AMH is a good marker of effective FSH treatment. In patients with cryptorchidism in the context of disorders of sex development, low serum AMH is suggestive of gonadal dysgenesis, whereas normal or high AMH is found in patients with isolated androgen synthesis defects or with androgen insensitivity. In syndromic disorders, assessment of serum AMH has shown that Sertoli cell function is preserved in boys with Klinefelter syndrome until mid-puberty, while it is affected in patients with Noonan, Prader-Willi or Down syndromes.

The miR-34b/MEK/ERK pathway is regulated by NR5A1 and promotes differentiation in primary bovine Sertoli cells

Sertoli cells play a key role in testicular development and spermatogenesis. It has been suggested that Sertoli cells differentiate after their proliferation ceases. Our previous study showed that miR-34b inhibits proliferation by targeting MAP2K1 mediated MEK/ERK signaling pathway in bovine immature Sertoli cells. Subsequent studies have revealed that the differentiation marker androgen receptor is upregulated during this process. However, the effect of the miR-34b/MEK/ERK pathway on immature bovine Sertoli cell differentiation and the underlying molecular mechanisms are yet to be explored. In this study, we determined that the miR-34b/MEK/ERK pathway was involved in the differentiation of primary Sertoli cells (PSCs) in response to retinoic acid. Transfection of an miR-34b mimic into PSCs promoted cell differentiation, whereas transfection of an miR-34b inhibitor into PSCs delayed it. Pharmacological inhibition of MEK/ERK signaling by AZD6244 promoted PSCs differentiation. Mechanistically, miR-34b promoted PSCs differentiation by inhibiting the MEK/ERK signaling pathway. Through a combination of bioinformatics analysis, dual-luciferase reporter assay, quantitative real-time PCR, and western blotting, nuclear receptor subfamily 5 group A member 1 (NR5A1) was identified as an upstream negative transcription factor of miR-34b. Furthermore, NR5A1 knockdown promoted Sertoli cell differentiation, whereas NR5A1 overexpression had the opposite effect. Together, this study revealed a new NR5A1/miR-34b/MEK/ERK axis that plays a significant role in Sertoli cell differentiation and provides a theoretical and experimental framework for further clarifying the regulation of cell differentiation in bovine PSCs.

The transcription factors Creb1 and Cebpb regulate Sox9 promoter activity in TM4 Sertoli cells

In Sertoli cells, the Sox9 gene is essential for testicular development and normal spermatogenesis. SOX9 is critical for postnatal Sertoli cells differentiation and proliferation in the testis. However, the molecular mechanisms that specifically regulate its expression are not entirely understood. Sox9 expression is regulated by CREB1 and CEBPB in other biological contexts such as during chondrogenesis and in rat thyroid follicular cells. We hypothesized that Sox9 promoter activity is regulated by CREB1 and CEBPB in Sertoli cells. Our results show that Sox9 expression is dependent on the activation of these transcription factors by the cAMP/PKA signaling pathway in TM4 Sertoli cells. Chromatin immunoprecipitation and promoter/reporter luciferase assays with 5' promoter deletions and site-directed mutagenesis demonstrated that CREB1 is being recruited to a DNA regulatory element at -141 bp of the Sox9 promoter region. Such regulation is dependent on the cAMP/PKA signaling pathway, resulting in phosphorylation of CREB1. Activation of Sox9 expression by CEBPB may involve its recruitment to the proximal promoter region by protein-protein interaction with CREB1. Thus, we have shown that the Sox9 promoter is being regulated by the transcription factors CREB1 and CEBPB in TM4 Sertoli cells and involve their recruitment to the proximal promoter region.

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.

BMP6 regulates AMH expression via SMAD1/5/8 in goat ovarian granulosa cells

Anti-Müllerian hormone (AMH) is produced by ovarian granulosa cells (GCs)and plays a major role in inhibiting the recruitment of primordial follicles and reducing the sensitivity of growing follicles to follicle-stimulating hormone (FSH). Bone morphogenetic protein 6 (BMP6) has similar spatiotemporal expression to AMH during follicular development, suggesting that BMP6 may regulate AMH expression. However, the specific mechanism by which BMP6 regulates AMH expression remains unclear. The objectives of this study were to examine the molecular pathway by which BMP6 regulates AMH expression. The results showed that BMP6 promoted the secretion and expression of AMH in goat ovarian GCs. Mechanistically, BMP6 upregulated the expression of sex-determining region Y-box 9 (SOX9) and GATA-binding factor 4 (GATA4), which was associated with the transcriptional initiation of AMH. AMH expression was significantly decreased by GATA4 knockdown. Moreover, BMP6 treatment promoted the phosphorylation of SMAD1/5/8, whereas inhibiting the SMAD1/5/8 signaling pathway significantly abolished BMP6-induced upregulation of AMH and GATA4 expression. Interestingly, the activation of SMAD1/5/8 alone did not affect the expression of AMH or GATA4. The results suggested that BMP6 upregulated GATA4 through the SMAD1/5/8 signaling pathway, which in turn promoted AMH expression.

Testicular Sertoli Cell Hormones in Differences in Sex Development

The Sertoli cells of the testes play an essential role during gonadal development, in addition to supporting subsequent germ cell survival and spermatogenesis. Anti-Müllerian hormone (AMH) is a member of the TGF-β superfamily, which is secreted by immature Sertoli cells from the 8th week of fetal gestation. lnhibin B is a glycoprotein, which is produced by the Sertoli cells from early in fetal development. In people with a Difference or Disorder of Sex Development (DSD), these hormones may be useful to determine the presence of testicular tissue and potential for spermatogenesis. However, fetal Sertoli cell development and function is often dysregulated in DSD conditions and altered production of Sertoli cell hormones may be detected throughout the life course in these individuals. As such this review will consider the role of AMH and inhibin B in individuals with DSD.

Case Report: Severe Gonadal Dysgenesis Causing 46,XY Disorder of Sex Development Due to a Novel NR5A1 Variant

Mutations in the nuclear receptor subfamily 5 group A member 1 (NR5A1) are the underlying cause of 10–20% of 46,XY disorders of sex development (DSDs). We describe a young girl with 46,XY DSD due to a unique novel mutation of the NR5A1 gene. An 11-year-old subject, raised as a female, was noticed to have clitromegly. She looked otherwise normal. However, her evaluation revealed a 46,XY karyotype, moderate clitromegly but otherwise normal female external genitalia, undescended atrophied testes, rudimentary uterus, no ovaries, and lack of breast development. Serum testosterone and estradiol were low, and gonadotropins were elevated. Adrenocortical function was normal. DNA was isolated from the peripheral leucocytes and used for whole exome sequencing. The results were confirmed by Sanger sequencing. We identified a novel mutation in NR5A1 changing the second nucleotide of the translation initiation codon (ATG>ACG) and resulting in a change of the first amino acid, methionine to threonine (p.Met1The). This led to severe gonadal dysgenesis with deficiency of testosterone and anti-Müllerian hormone (AMH) secretion. Lack of the former led to the development of female external genitalia, and lack of the latter allowed the Müllerian duct to develop into the uterus and the upper vagina. The patient has a female gender identity. Bilateral orchidectomy was performed and showed severely atrophic testes. Estrogen/progesterone therapy was initiated with excellent breast development and normal cyclical menses. In summary, we describe a severely affected case of 46,XY DSD due to a novel NR5A1 mutation involving the initiation codon that fully explains the clinical phenotype in this subject.

Expression of G-Protein-Coupled Estrogen Receptor (GPER) in Whole Testicular Tissue and Laser-Capture Microdissected Testicular Compartments of Men with Normal and Aberrant Spermatogenesis

Simple Summary

Nowadays, there is no doubt that estrogens play an important role in male reproduction, affecting testicular cell differentiation, proliferation, apoptosis and metabolism. It is also widely believed that intratesticular balance of androgens and estrogens is crucial for the testicular development and function and that the increased testicular estrogen production may be associated with spermatogenic failure. There is also growing epidemiological evidence that the exposure of men to endocrine disruptors demonstrating estrogenic activity (xenoestrogens) may lead to impairment of male fertility via interference with estrogen signaling pathways. Besides the two classical nuclear estrogen receptors, the membrane-bound G protein-coupled estrogen receptor (GPER) was described in human testicular tissue. However, there are little data on its expression in testes with disturbed spermatogenesis. In this study, we investigated the GPER expression pattern in biopsies of azoospermic men with complete and aberrant spermatogenesis. Our results showed an increased expression of the GPER in testes with impaired spermatogenesis. Moreover, they indicate a possible involvement of estrogen signaling through GPER in disturbed function of Sertoli cells—the cells that support spermatogenic process.

Abstract

In this study, we retrospectively investigated GPER expression in biopsies of azoospermic men with complete (obstructive azoospermia—OA) and aberrant spermatogenesis (nonobstructive azoospermia—NOA). Each biopsy was histologically evaluated with morphometry. The testicular GPER expression was analyzed by the immunohistochemistry and RT-PCR technique in the whole testicular tissue and in seminiferous tubules and Leydig cells after laser-capture microdissection. In laser-microdissected compartments, we also analyzed transcriptional expression of selected Leydig (CYP17A1, HSD17B3, StAR) and Sertoli cell (AMH, SCF, BMP4) function markers. Immunohistochemical staining revealed expression of GPER in the cytoplasm of Leydig and Sertoli cells. Its stronger intensity was observed in Sertoli cells of NOA biopsies. The RT-PCR analysis of the GPER mRNA level unequivocally showed its increased expression in seminiferous tubules (i.e., Sertoli cells), not Leydig cells in NOA biopsies. This increased expression correlated positively with the transcriptional level of AMH—a marker of Sertoli cell immaturity, as well as FSH serum level in NOA but not in the OA group. Our results clearly demonstrate altered GPER expression in testes with primary spermatogenic impairment that might be related to Sertoli cell maturity/function.

Genetics of anti-Müllerian hormone and its signaling pathway

Anti-Müllerian hormone (AMH) is a member of the TGF-β family produced essentially by the supporting somatic cells of the testis. Initially known for its inhibiting role upon the development of female internal organs, AMH has been shown to exert many other effects namely upon germ cells. Circulating AMH reflects the ovarian reserve of young developing follicles and is used to evaluate the fertility potential in assisted reproduction. The signaling pathway of AMH is both similar and different from that of other members of the TGF-β family. Like these, it signals through two distinct serine/threonine receptors, type 1 and type 2, that phosphorylate cytoplasmic effectors, the Smads. It also shares type 1 receptors and Smads with other members of the family. However, AMH is the only family member with its own, dedicated, ligand-specific type 2 receptor, AMHR2. The monogamic relationship between AMH and AMHR2 is supported by molecular studies of the Persistent Müllerian Duct Syndrome, characterized by the presence of Müllerian derivatives in otherwise normally virilized males: mutations of AMH or AMHR2 are clinically indistinguishable.

AMH Regulation by Steroids in the Mammalian Testis: Underlying Mechanisms and Clinical Implications

Anti-Müllerian hormone (AMH) is a distinctive biomarker of the immature Sertoli cell. AMH expression, triggered by specific transcription factors upon fetal Sertoli cells differentiation independently of gonadotropins or sex steroids, drives Müllerian duct regression in the male, preventing the development of the uterus and Fallopian tubes. AMH continues to be highly expressed by Sertoli until the onset of puberty, when it is downregulated to low adult levels. FSH increases testicular AMH output by promoting immature Sertoli cell proliferation and individual cell expression. AMH secretion also showcases a differential regulation exerted by intratesticular levels of androgens and estrogens. In the fetus and the newborn, Sertoli cells do not express the androgen receptor, and the high androgen concentrations do not affect AMH expression. Conversely, estrogens can stimulate AMH production because estrogen receptors are present in Sertoli cells and aromatase is stimulated by FSH. During childhood, sex steroids levels are very low and do not play a physiological role on AMH production. However, hyperestrogenic states upregulate AMH expression. During puberty, testosterone inhibition of AMH expression overrides stimulation by estrogens and FSH. The direct effects of sex steroids on AMH transcription are mediated by androgen receptor and estrogen receptor α action on AMH promoter sequences. A modest estrogen action is also mediated by the membrane G-coupled estrogen receptor GPER. The understanding of these complex regulatory mechanisms helps in the interpretation of serum AMH levels found in physiological or pathological conditions, which underscores the importance of serum AMH as a biomarker of intratesticular steroid concentrations.

What Does Androgen Receptor Signaling Pathway in Sertoli Cells During Normal Spermatogenesis Tell Us?

Androgen receptor signaling pathway is necessary to complete spermatogenesis in testes. Difference between androgen binding location in Sertoli cell classifies androgen receptor signaling pathway into classical signaling pathway and non-classical signaling pathway. As the only somatic cell type in seminiferous tubule, Sertoli cells are under androgen receptor signaling pathway regulation via androgen receptor located in cytoplasm and plasma membrane. Androgen receptor signaling pathway is able to regulate biological processes in Sertoli cells as well as germ cells surrounded between Sertoli cells. Our review will summarize the major discoveries of androgen receptor signaling pathway in Sertoli cells and the paracrine action on germ cells. Androgen receptor signaling pathway regulates Sertoli cell proliferation and maturation, as well as maintain the integrity of blood-testis barrier formed between Sertoli cells. Also, Spermatogonia stem cells achieve a balance between self-renewal and differentiation under androgen receptor signaling regulation. Meiotic and post-meiotic processes including Sertoli cell - Spermatid attachment and Spermatid development are guaranteed by androgen receptor signaling until the final sperm release. This review also includes one disease related to androgen receptor signaling dysfunction named as androgen insensitivity syndrome. As a step further ahead, this review may be conducive to develop therapies which can cure impaired androgen receptor signaling in Sertoli cells.

Recent advancement in the treatment of boys and adolescents with hypogonadism

Clinical manifestations and the need for treatment varies according to age in males with hypogonadism. Early foetal-onset hypogonadism results in disorders of sex development (DSD) presenting with undervirilised genitalia whereas hypogonadism established later in foetal life presents with micropenis, cryptorchidism and/or micro-orchidism. After the period of neonatal activation of the gonadal axis has waned, the diagnosis of hypogonadism is challenging because androgen deficiency is not apparent until the age of puberty. Then, the differential diagnosis between constitutional delay of puberty and central hypogonadism may be difficult. During infancy and childhood, treatment is usually sought because of micropenis and/or cryptorchidism, whereas lack of pubertal development and relative short stature are the main complaints in teenagers. Testosterone therapy has been the standard, although off-label, in the vast majority of cases. However, more recently alternative therapies have been tested: aromatase inhibitors to induce the hypothalamic-pituitary-testicular axis in boys with constitutional delay of puberty and replacement with GnRH or gonadotrophins in those with central hypogonadism. Furthermore, follicle-stimulating hormone (FSH) priming prior to hCG or luteinizing hormone (LH) treatment seems effective to induce an enhanced testicular enlargement. Although the rationale for gonadotrophin or GnRH treatment is based on mimicking normal physiology, long-term results are still needed to assess their impact on adult fertility.

Diagnosis of Male Central Hypogonadism During Childhood

The diagnosis of male central (or hypogonadotropic) hypogonadism, typically based on low luteinizing hormone (LH) and testosterone levels, is challenging during childhood since both hormones are physiologically low from the sixth month until the onset of puberty. Conversely, follicle-stimulating hormone (FSH) and anti-Müllerian hormone (AMH), which show higher circulating levels during infancy and childhood, are not used as biomarkers for the condition. We report the case of a 7-year-old boy with a history of bilateral cryptorchidism who showed repeatedly low FSH and AMH serum levels during prepuberty. Unfortunately, the diagnosis could not be ascertained until he presented with delayed puberty at the age of 14 years. A gonadotropin-releasing hormone (GnRH) test showed impaired LH and FSH response. By then, his growth and bone mineralization were partially impaired. Gene panel sequencing identified a variant in exon 15 of FGFR1, affecting the tyrosine kinase domain of the receptor, involved in GnRH neuron migration and olfactory bulb morphogenesis. Testosterone replacement was started, which resulted in the development of secondary sexual characteristics and partial improvement of bone mineral density. This case illustrates the difficulty in making the diagnosis of central hypogonadism in boys during childhood based on classical criteria, and how serum FSH and AMH assessment may be helpful if it is suspected before the age of puberty, and confirm it using next-generation sequencing. The possibility of making an early diagnosis of central hypogonadism may be useful for a timely start of hormone replacement therapy, and to avoid delays that could affect growth and bone health as well as psychosocial adjustment.

AMH and AMHR2 Involvement in Congenital Disorders of Sex Development

Anti-müllerian hormone (AMH) is 1 of the 2 testicular hormones involved in male development of the genitalia during fetal life. When the testes differentiate, AMH is secreted by Sertoli cells and binds to its specific receptor type II (AMHR2) on the müllerian ducts, inducing their regression. In the female fetus, the lack of AMH allows the müllerian ducts to form the fallopian tubes, the uterus, and the upper part of the vagina. The human AMH gene maps to 19p13.3 and consists of 5 exons and 4 introns spanning 2,764 bp. The AMHR2 gene maps to 12q13.13, consists of 11 exons, and is 7,817 bp long. Defects in the AMH pathway are the underlying etiology of a subgroup of disorders of sex development (DSD) in 46,XY patients. The condition is known as the persistent müllerian duct syndrome (PMDS), characterized by the existence of a uterus and fallopian tubes in a boy with normally virilized external genitalia. Approximately 200 cases of patients with PMDS have been reported to date with clinical, biochemical, and molecular genetic characterization. An updated review is provided in this paper. With highly sensitive techniques, AMH and AMHR2 expression has also been detected in other tissues, and massive sequencing technologies have unveiled variants in AMH and AMHR2 genes in hitherto unsuspected conditions.

Identification of Potential Genes in Pathogenesis and Diagnostic Value Analysis of Partial Androgen Insensitivity Syndrome Using Bioinformatics Analysis

BACKGROUND

Androgen insensitivity syndrome (AIS) is a rare X-linked genetic disease and one of the causes of 46,XY disorder of sexual development. The unstraightforward diagnosis of AIS and the gender assignment dilemma still make a plague for this disorder due to the overlapping clinical phenotypes.

METHODS

Peripheral blood mononuclear cells (PBMCs) of partial AIS (PAIS) patients and healthy controls were separated, and RNA-seq was performed to investigate transcriptome variance. Then, tissue-specific gene expression, functional enrichment, and protein-protein interaction (PPI) network analyses were performed; and the key modules were identified. Finally, the RNA expression of differentially expressed genes (DEGs) of interest was validated by quantitative real-time PCR (qRT-PCR).

RESULTS

In our dataset, a total of 725 DEGs were captured, with functionally enriched reproduction and immune-related pathways and Gene Ontology (GO) functions. The most highly specific systems centered on hematologic/immune and reproductive/endocrine systems. We finally filtered out CCR1, PPBP, PF4, CLU, KMT2D, GP6, and SPARC by the key gene clusters of the PPI network and manual screening of tissue-specific gene expression. These genes provide novel insight into the pathogenesis of AIS in the immune system or metabolism and bring forward possible molecular markers for clinical screening. The qRT-PCR results showed a consistent trend in the expression levels of related genes between PAIS patients and healthy controls.

CONCLUSION

The present study sheds light on the molecular mechanisms underlying the pathogenesis and progression of AIS, providing potential targets for diagnosis and future investigation.

Molecular mechanisms underlying AMH elevation in hyperoestrogenic states in males

Anti-Müllerian hormone (AMH) is secreted by Sertoli cells of the testes from early fetal life until puberty, when it is downregulated by androgens. In conditions like complete androgen insensitivity syndrome (CAIS), AMH downregulation does not occur and AMH increases at puberty, due in part to follicle-stimulating hormone (FSH) effect. However, other conditions like Peutz-Jeghers syndrome (PJS), characterised by low FSH, also have increased AMH. Because both CAIS and PJS may present as hyperoestrogenic states, we tested the hypothesis that oestradiol (E2) upregulates AMH expression in peripubertal Sertoli cells and explored the molecular mechanisms potentially involved. The results showed that E2 is capable of inducing an upregulation of endogenous AMH and of the AMH promoter activity in the prepubertal Sertoli cell line SMAT1, signalling through ERα binding to a specific ERE sequence present on the hAMH promoter. A modest action was also mediated through the membrane oestrogen receptor GPER. Additionally, the existence of ERα expression in Sertoli cells in patients with CAIS was confirmed by immunohistochemistry. The evidence presented here provides biological plausibility to the hypothesis that testicular AMH production increases in clinical conditions in response to elevated oestrogen levels.

What Does AMH Tell Us in Pediatric Disorders of Sex Development?

Disorders of sex development (DSD) are conditions where genetic, gonadal, and/or internal/external genital sexes are discordant. In many cases, serum testosterone determination is insufficient for the differential diagnosis. Anti-Müllerian hormone (AMH), a glycoprotein hormone produced in large amounts by immature testicular Sertoli cells, may be an extremely helpful parameter. In undervirilized 46,XY DSD, AMH is low in gonadal dysgenesis while it is normal or high in androgen insensitivity and androgen synthesis defects. Virilization of a 46,XX newborn indicates androgen action during fetal development, either from testicular tissue or from the adrenals or placenta. Recognizing congenital adrenal hyperplasia is usually quite easy, but other conditions may be more difficult to identify. In 46,XX newborns, serum AMH measurement can easily detect the existence of testicular tissue, leading to the diagnosis of ovotesticular DSD. In sex chromosomal DSD, where the gonads are more or less dysgenetic, AMH levels are indicative of the amount of functioning testicular tissue. Finally, in boys with a persistent Müllerian duct syndrome, undetectable or very low serum AMH suggests a mutation of the AMH gene, whereas normal AMH levels orient toward a mutation of the AMH receptor.

Androgens downregulate anti-Müllerian hormone promoter activity in the Sertoli cell through the androgen receptor and intact steroidogenic factor 1 sites

Testicular anti-Müllerian hormone (AMH) production is inhibited by androgens around pubertal onset, as observed under normal physiological conditions and in patients with precocious puberty. In agreement, AMH downregulation is absent in patients with androgen insensitivity. The molecular mechanisms underlying the negative regulation of AMH by androgens remain unknown. Our aim was to elucidate the mechanisms through which androgens downregulate AMH expression in the testis. A direct negative effect of androgens on the transcriptional activity of the AMH promoter was found using luciferase reporter assays in the mouse prepubertal Sertoli cell line SMAT1. A strong inhibition of AMH promoter activity was seen in the presence of both testosterone and DHT and of the androgen receptor. By site-directed mutagenesis and chromatin immunoprecipitation assays, we showed that androgen-mediated inhibition involved the binding sites for steroidogenic factor 1 (SF1) present in the proximal promoter of the AMH gene. In this study, we describe for the first time the mechanism behind AMH inhibition by androgens, as seen in physiological and pathological conditions in males. Inhibition of AMH promoter activity by androgens could be due to protein-protein interactions between the ligand-bound androgen receptor and SF1 or by blockage of SF1 binding to its sites on the AMH promoter.

Differential Regulation of TLE3 in Sertoli Cells of the Testes during Postnatal Development

Spermatogenesis is a process by which haploid cells differentiate from germ cells in the seminiferous tubules of the testes. TLE3, a transcriptional co-regulator that interacts with DNA-binding factors, plays a role in the development of somatic cells. However, no studies have shown its role during germ cell development in the testes. Here, we examined TLE3 expression in the testes during spermatogenesis. TLE3 was highly expressed in mouse testes and was dynamically regulated in different cell types of the seminiferous tubules, spermatogonia, spermatids, and Sertoli cells, but not in the spermatocytes. Interestingly, TLE3 was not detected in Sertoli cells on postnatal day 7 (P7) but was expressed from P10 onward. The microarray analysis showed that the expression of numerous genes changed upon TLE3 knockdown in a Sertoli cell line TM4. These include 1597 up-regulated genes and 1452 down-regulated genes in TLE3-knockdown TM4 cells. Ingenuity Pathway Analysis (IPA) showed that three factors were up-regulated and two genes were down-regulated upon TLE3 knockdown in TM4 cells. The abnormal expression of the three factors is associated with cellular malfunctions such as abnormal differentiation and Sertoli cell formation. Thus, TLE3 is differentially expressed in Sertoli cells and plays a crucial role in regulating cell-specific genes involved in the differentiation and formation of Sertoli cells during testicular development.

A mutation inactivating the distal SF1 binding site on the human anti-Müllerian hormone promoter causes persistent Müllerian duct syndrome

The persistent Müllerian duct syndrome (PMDS) is a 46,XY disorder of sexual development characterized by the persistence of Müllerian duct derivatives, uterus and tubes, in otherwise normally masculinized males. The condition, transmitted as a recessive autosomal trait, is usually due to mutations in either the anti-Müllerian hormone (AMH) gene or its main receptor. Many variants of these genes have been described, all targeting the coding sequences. We report the first case of PMDS due to a regulatory mutation. The AMH promoter contains two binding sites for steroidogenic factor 1 (SF1), one at −102 and the other at −228. Our patient carries a single base deletion at −225, significantly decreasing its capacity for binding SF1, as measured by the electrophoresis mobility shift assay. Furthermore, by linking the AMH promoter to the luciferase gene, we show that the transactivation capacity of the promoter is significantly decreased by the mutation, in contrast to the disruption of the −102 binding site. To explain the difference in impact we hypothesize that SF1 could partially overcome the lack of binding to the −102 binding site by interacting with a GATA4 molecule linked to a nearby response element. We show that disruption of both the −102 SF1 and the −84 GATA response elements significantly decreases the transactivation capacity of the promoter. In conclusion, we suggest that the distance between mutated SF1 sites and potentially rescuing GATA binding motifs might play a role in the development of PMDS.

Deciphering Cell Lineage Specification during Male Sex Determination with Single-Cell RNA Sequencing

The gonad is a unique biological system for studying cell-fate decisions. However, major questions remain regarding the identity of somatic progenitor cells and the transcriptional events driving cell differentiation. Using time-series single-cell RNA sequencing on XY mouse gonads during sex determination, we identified a single population of somatic progenitor cells prior to sex determination. A subset of these progenitors differentiates into Sertoli cells, a process characterized by a highly dynamic genetic program consisting of sequential waves of gene expression. Another subset of multipotent cells maintains their progenitor state but undergoes significant transcriptional changes restricting their competence toward a steroidogenic fate required for the differentiation of fetal Leydig cells. Our findings confirm the presence of a unique multipotent progenitor population in the gonadal primordium that gives rise to both supporting and interstitial lineages. These also provide the most granular analysis of the transcriptional events occurring during testicular cell-fate commitment.

Comparing the role of anti-Müllerian hormone as a marker of FSH action in male and female fertility

INTRODUCTION

Originally limited to the assessment of disorders of sex development, anti-Müllerian hormone (AMH) measurement has more recently been extended to several conditions affecting the reproductive axis in males and females. Follicle-stimulating hormone (FSH) regulation of gonadal function has been extensively studied, but its role on AMH production has been explored only recently.

AREAS COVERED

We addressed the relationship between FSH action on the gonads and the usefulness of AMH as a marker in conditions affecting the reproductive axis.

EXPERT OPINION

Sertoli cells are the most active cell population in the prepubertal testis. Serum AMH is an excellent marker of FSH action on Sertoli cell proliferation and function in patients with hypogonadotropic hypogonadism. Low serum AMH is expected to predict low sperm production and prompts initial FSH treatment followed by human chorionic gonadotropin (hCG) or luteinizing hormone (LH) addition. Gonadotropin treatment may be more effective if installed to mimic the postnatal activation stage of the hypothalamic-pituitary-testicular axis. In females, AMH secretion by small antral follicles is stimulated by FSH. Elevated AMH indicates increased follicle numbers and should be considered as a potential contraindication of gonadotropin treatment in infertile patients due to an increased risk of developing ovarian hyperstimulation syndrome.

Cotreatment of IGF1 and Fadrozole Upregulates the Expression of RSPO1, SOX9, and AMH in Chicken Embryos

Insulin-like growth factor-1 (IGF1) and anti-aromatase synergistically increase the rate and stability of female-to-male sex reversal as well as pre- and postnatal weight gains in hatched chickens. This study aimed at assessing gene expression profiles of chicken embryos treated with IGF1 and fadrozole. Day 3.5 fertile eggs were in ovo injected with one of IGF1, fadrozole anti-aromatase, combined IGF1 and fadrozole, or sham injection. The expression profile was studied on day 6 and day 11 of the embryonic development following gonadal differentiation. On day 6 of embryonic development, simultaneous injection of IGF1 and fadrozole significantly upregulated the expression of RSPO1, AMH, and SOX9 in genetically female embryos compared to single injections and control groups. Also, a higher expression of ESR1 and BMP4 was observed in genetically male embryos on day 6 compared to the control group. In day 11 embryos, a higher expression of BMP4 was detected in both males and females of the IGF1 and fadrozole-administered group compared to the sham injection cohort. In conclusion, the results of this study indicate that combined effects of IGF1 and fadrozole induce female-to-male sex reversal by increasing the expression of testis developmental factors rather than attenuating ovary developmental factors.

In Vivo Ablation of the Conserved GATA-Binding Motif in the Amh Promoter Impairs Amh Expression in the Male Mouse

GATA4 is an essential transcriptional regulator required for gonadal development, differentiation, and function. In the developing testis, proposed GATA4-regulated genes include steroidogenic factor 1 (Nr5a1), SRY-related HMG box 9 (Sox9), and anti-Müllerian hormone (Amh). Although some of these genes have been validated as genuine GATA4 targets, it remains unclear whether GATA4 is a direct regulator of endogenous Amh transcription. We used a CRISPR/Cas9-based approach to specifically inactivate or delete the sole GATA-binding motif of the proximal mouse Amh promoter. AMH mRNA and protein levels were assessed at developmental time points corresponding to elevated AMH levels: fetal and neonate testes in males and adult ovaries in females. In males, loss of GATA binding to the Amh promoter significantly reduced Amh expression. Although the loss of GATA binding did not block the initiation of Amh transcription, AMH mRNA and protein levels failed to upregulate in the developing fetal and neonate testis. Interestingly, adult male mice presented no anatomical anomalies and had no evidence of retained Müllerian duct structures, suggesting that AMH levels, although markedly reduced, were sufficient to masculinize the male embryo. In contrast to males, GATA binding to the Amh promoter was dispensable for Amh expression in the adult ovary. These results provide conclusive evidence that in males, GATA4 is a positive modulator of Amh expression that works in concert with other key transcription factors to ensure that the Amh gene is sufficiently expressed in a correct spatiotemporal manner during fetal and prepubertal testis development.

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.

Male Central Hypogonadism in Paediatrics - the Relevance of Follicle-stimulating Hormone and Sertoli Cell Markers

The definition of male hypogonadism, used in adult endocrinology, is not fully applicable to paediatrics. A clear understanding of the developmental physiology of the hypothalamic-pituitary-testicular axis is essential for the comprehension of the pathogenesis of hypogonadal states in boys and for the establishment of adequate definitions and classifications in paediatric ages. This is particularly true for central hypogonadism, usually called hypogonadotropic in adults. Because childhood is a period characterised by a physiological state of low gonadotropin and testosterone production, these markers of hypogonadism, typically used in adult endocrinology, are uninformative in the child. This review is focused on the physiological importance of prepubertal Sertoli cell markers - anti-Müllerian hormone (AMH) and inhibin B - and of the intratesticular actions of follicle-stimulating hormone (FSH) and testosterone during early infancy and the first stages of pubertal development. We discuss the role of FSH in regulating the proliferation of Sertoli cells - the main determinant of prepubertal testicular volume - and the secretion of AMH and inhibin B. We also address how intratesticular testosterone concentrations have different effects on the seminiferous tubule function in early infancy and during pubertal development.

Single cell transcriptome sequencing: A new approach for the study of mammalian sex determination

Mammalian sex determination is a highly complex developmental process that is particularly difficult to study due to the limited number of gonadal cells present at the bipotential stage, the large cellular heterogeneity in both testis and ovaries and the rapid sex-dependent differentiation processes. Single-cell RNA-sequencing (scRNA-seq) circumvents the averaging artifacts associated with methods traditionally used to profile bulk populations of cells. It is a powerful tool that allows the identification and classification of cell populations in a comprehensive and unbiased manner. In particular, scRNA-seq enables the tracing of cells along developmental trajectories and characterization of the transcriptional dynamics controlling their differentiation. In this review, we describe the current state-of-the-art experimental methods used for scRNA-seq and discuss their strengths and limitations. Additionally, we summarize the multiple key insights that scRNA-seq has provided to the understanding of mammalian sex determination. Finally, we briefly discuss the future of this technology, as well as complementary applications in single cell -omics in the context of mammalian sex determination.

Hydroxysteroid (17β) dehydrogenase 1 expressed by Sertoli cells contributes to steroid synthesis and is required for male fertility

The pituitary gonadotrophins and testosterone are the main hormonal regulators of spermatogenesis, but estradiol is also known to play a role in the process. The hormonal responses in the testis are partially mediated by somatic Sertoli cells that provide nutritional and physical support for differentiating male germ cells. Hydroxysteroid (17β) dehydrogenase 1 (HSD17B1) is a steroidogenic enzyme that especially catalyzes the conversion of low potent 17keto-steroids to highly potent 17β-hydroxysteroids. In this study, we show that Hsd17b1 is highly expressed in Sertoli cells of fetal and newborn mice, and HSD17B1 knockout males present with disrupted spermatogenesis with major defects, particularly in the head shape of elongating spermatids. The cell-cell junctions between Sertoli cells and germ cells were disrupted in the HSD17B1 knockout mice. This resulted in complications in the orientation of elongating spermatids in the seminiferous epithelium, reduced sperm production, and morphologically abnormal spermatozoa. We also showed that the Sertoli cell-expressed HSD17B1 participates in testicular steroid synthesis, evidenced by a compensatory up-regulation of HSD17B3 in Leydig cells. These results revealed a novel role for HSD17B1 in the control of spermatogenesis and male fertility, and that Sertoli cells significantly contribute to steroid synthesis in the testis.-Hakkarainen, J., Zhang, F.-P., Jokela, H., Mayerhofer, A., Behr, R., Cisneros-Montalvo, S., Nurmio, M., Toppari, J., Ohlsson, C., Kotaja, N., Sipilä, P., Poutanen, M. Hydroxysteroid (17β) dehydrogenase 1 expressed by Sertoli cells contributes to steroid synthesis and is required for male fertility.

Anti-Müllerian Hormone and Testicular Function in Prepubertal Boys With Cryptorchidism

INTRODUCTION

The functional capacity of the testes in prepubertal boys with cryptorchidism before treatment has received very little attention. The assessment of testicular function at diagnosis could be helpful in the understanding of the pathophysiology of cryptorchidism and in the evaluation of the effect of treatment. Anti-Müllerian hormone is a well-accepted Sertoli cell biomarker to evaluate testicular function during childhood without the need for stimulation tests.

OBJECTIVE

The aim of the study was to assess testicular function in prepubertal children with cryptorchidism before orchiopexy, by determining serum anti-Müllerian hormone (AMH). We also evaluated serum gonadotropins and testosterone and looked for associations between testicular function and the clinical characteristics of cryptorchidism.

MATERIALS AND METHODS

We performed a retrospective, cross-sectional, analytical study at a tertiary pediatric public hospital. All clinical charts of patients admitted at the outpatient clinic, and recorded in our database with the diagnosis of cryptorchidism, were eligible. The main outcome measure of the study was the serum concentration of AMH. Secondary outcome measures were serum LH, FSH, and testosterone. For comparison, serum hormone levels from a normal population of 179 apparently normal prepubertal boys were used.

RESULTS

Out of 1,557 patients eligible in our database, 186 with bilateral and 124 with unilateral cryptorchidism were selected using a randomization software. Median AMH standard deviation score was below 0 in both the bilaterally and the unilaterally cryptorchid groups, indicating that testicular function was overall decreased in patients with cryptorchidism. Serum AMH was significantly lower in boys with bilateral cryptorchidism as compared with controls and unilaterally cryptorchid patients between 6 months and 1.9 years and between 2 and 8.9 years of age. Serum AMH below the normal range reflected testicular dysfunction in 9.5-36.5% of patients according to the age group in bilaterally cryptorchid boys and 6.3-16.7% in unilaterally cryptorchid boys. FSH was elevated in 8.1% and LH in 9.1% of boys with bilateral cryptorchidism, most of whom were anorchid. In patients with present testes, gonadotropins were only mildly elevated in less than 5% of the cases. Basal testosterone was mildly decreased in patients younger than 6 months old, and uninformative during childhood.

CONCLUSION

Prepubertal boys with cryptorchidism, especially those with bilaterally undescended gonads, have decreased AMH production. Although serum AMH may fall within the normal range, there is a considerable prevalence of testicular dysfunction during childhood in this frequent condition.

Puberty arises with testicular alterations and defective AMH expression in rams prenatally exposed to testosterone

The male gonadal tissue can be a sensitive target to the reprogramming effects of testosterone (T) during prenatal development. We have demonstrated that male lambs born to dams receiving T during pregnancy-a model system to the polycystic ovary syndrome (PCOS)-show a decreased number of germ cells early in life, and when adult, a reduced amount of sperm and ejaculate volume. These findings are a key to put attention to the male offspring of women bearing PCOS, as they are exposed to increased levels of androgen during pregnancy which can reprogram their reproductive outcome. A possible origin of these defects can be a disruption in the expression of the anti-Müllerian hormone (AMH), due to its critical role in gonadal function at many postnatal stages. Therefore, we addressed the impact of prenatal T excess on the expression of AMH and factors related to its expression like AP2, SOX9, FSHR, and AR in the testicular tissue through real-time PCR during the peripubertal age. We also analyzed the testicular morphology and quantified the number of Sertoli cells and germ cells to evaluate any further defect in the testicle. Experiments were performed in rams at 24 wk of age, hence, prior puberty. The experimental animals (T-males) consisted of rams born to mothers receiving 30 mg testosterone twice a wk from Day 30 to 90 of pregnancy and then increased to 40 mg until Day 120 of pregnancy. The control males (C-males) were born to mothers receiving the vehicle of the hormone. We found a significant increase in the expression of the mRNA of AMH and SOX9, but not of the AP2, FHSR nor AR, in the T-males. Moreover, T-males showed a dramatic decrease in the number of germ cells, together with a decrease in the weight of their testicles. The findings of the present study show that before puberty, T-males are manifesting clear signs of disruption in the gonadal functions probably due to an alteration in the expression pattern of the AMH gene. The precise way by which T reprograms the expression of AMH gene remains to be established.

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

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

Male-biased miR-92 from early chicken embryonic gonads directly targets ATRX and DDX3X

MiR-17-92 cluster consists of multifunctional miRNAs related to gonadal development in mammals. Our preliminary data showed that gga-miR-92 was male-biased in chicken embryonic gonads at E5.5 and E6.5. MiR-92(a-2) and two putative targets (ATRX and DDX3X) were highly conserved and located on mammalian Chromosome X but on autosomes in chicken. Here, we studied the expression and interaction of miR-92 and the targets (ATRX and DDX3X) in chicken embryonic gonads. What's more, male-biased miR-92 shows an opposite expression tendency with ATRX and DDX3X in eight embryonic stages and different tissues at E10.5 by qRT-PCR. To verify the regulation relationship between miR-92 and two targets, we performed dual-luciferase reporter assay in DF1, overexpression and inhibition of miR-92 in chicken embryonic fibroblasts (CEFs). The results show that miR-92 directly targets ATRX and DDX3X by binding the 3' un-translated region (3'-UTR), and the over-expression and inhibition of miR-92 negatively regulates ATRX and DDX3X. After the identification of the expression of their downstream genes (AMH and WNT4) in mRNA level, we found that there is no regulatory relationship between ATRX and DDX3X. The overall results indicate that miR-92 may perform roles in early chicken gonadogenesis by regulating the expressions of ATRX and DDX3X, respectively.

Altered secretion of Sertoli cells hormones in 2-year-old prepubertal cryptorchid boys: a cross-sectional study

In cryptorchid boys, failures in germ cell development have been clearly established. Some studies reported some abnormalities in Sertoli cells morphology but the results regarding their endocrine secretion remain controversial. To compare testicular hormone levels in young boys with and without cryptorchidism, we performed a cross-sectional hospital-based study. From surgery appointment records, we identified a case group of boys with unilateral or bilateral cryptorchidism and a control group undergoing dental care, minor osteoarticular or dermal surgery. Blood samples were withdrawn during the surgical procedure to perform testosterone, inhibin B and anti-müllerian hormone (AMH) immunoassays. We included 27 cryptorchid boys and 27 controls aged of 26.6 vs. 24.2 months, respectively (p = 0.172) far from the post-natal mini-puberty and the corresponding hormonal surges. Age-adjusted AMH and inhibin B levels were significantly lower in cryptorchid than in control boys (AMH: 87 ng/mL vs. 135 ng/mL; p = 0.009, inhibin B: 97 pg/mL vs. 133 pg/mL; p = 0.019, respectively). Moreover, AMH and inhibin B levels were significantly lower in the bilateral cryptorchid subgroup, being 50% lower than in the controls (p = 0.011 and 0.019, respectively) and while both hormones levels were independent in controls, they became strongly correlated in bilateral cryptorchid boys (R² = 0.75, p = 0.001). In addition, testosterone levels were still detectable in some boys, with significantly lower levels in cryptorchid group than in controls. Overall, 2-year-old cryptorchid patients presented a simultaneous and significant drop in AMH and inhibin B levels, suggesting a functional defect of Sertoli cells. This deficiency appeared more pronounced in bilateral cryptorchidism and thus, regarding the pivotal role of Sertoli cells in germ cell development, it may explain the compromised fertility found later in men born with such a malformation.

New NR5A1 mutations and phenotypic variations of gonadal dysgenesis

Mutations in NR5A1 have been reported as a frequent cause of 46,XY disorders of sex development (DSD) associated to a broad phenotypic spectrum ranging from infertility, ambiguous genitalia, anorchia to gonadal dygenesis and female genitalia. Here we present the clinical follow up of four 46,XY DSD patients with three novel heterozygous mutations in the NR5A1 gene leading to a p.T40P missense mutation and a p.¹⁸DKVSG²²del nonframeshift deletion in the DNA-binding domain and a familiar p.Y211Tfs*83 frameshift mutation. Functional analysis of the missense and nonframeshift mutation revealed a deleterious character with loss of DNA-binding and transactivation capacity. Both, the mutations in the DNA-binding domain, as well as the familiar frameshift mutation are associated with highly variable endocrine values and phenotypic appearance. Phenotypes vary from males with spontaneous puberty, substantial testosterone production and possible fertility to females with and without Müllerian structures and primary amenorrhea. Exome sequencing of the sibling’s family revealed TBX2 as a possible modifier of gonadal development in patients with NR5A1 mutations.

Anti-Müllerian hormone as a marker of steroid and gonadotropin action in the testis of children and adolescents with disorders of the gonadal axis

In pediatric patients, basal testosterone and gonadotropin levels may be uninformative in the assessment of testicular function. Measurement of serum anti-Müllerian hormone (AMH) has become increasingly widespread since it provides information about the activity of the male gonad without the need for dynamic tests, and also reflects the action of FSH and androgens within the testis. AMH is secreted in high amounts by Sertoli cells from fetal life until the onset of puberty. Basal AMH expression is not dependent on gonadotropins or sex steroids; however, FSH further increases and testosterone inhibits AMH production. During puberty, testosterone induces Sertoli cell maturation, and prevails over FSH on AMH regulation. Therefore, AMH production decreases. Serum AMH is undetectable in patients with congenital or acquired anorchidism, or with complete gonadal dysgenesis. Low circulating levels of AMH may reflect primary testicular dysfunction, e.g. in certain patients with cryptorchidism, monorchidism, partial gonadal dysgenesis, or central hypogonadism. AMH is low in boys with precocious puberty, but it increases to prepubertal levels after successful treatment. Conversely, serum AMH remains at high, prepubertal levels in boys with constitutional delay of puberty. Serum AMH measurements are useful, together with testosterone determination, in the diagnosis of patients with ambiguous genitalia: both are low in patients with gonadal dysgenesis, including ovotesticular disorders of sex development, testosterone is low but AMH is in the normal male range or higher in patients with disorders of androgen synthesis, and both hormones are normal or high in patients with androgen insensitivity. Finally, elevation of serum AMH above normal male prepubertal levels may be indicative of rare cases of sex-cord stromal tumors or Sertoli cell-limited disturbance in the McCune Albright syndrome.

Identification of male-biased microRNA-107 as a direct regulator for nuclear receptor subfamily 5 group A member 1 based on sexually dimorphic microRNA expression profiling from chicken embryonic gonads

Several studies indicate that sexual dimorphic microRNAs (miRNAs) in chicken gonads are likely to have important roles in sexual development, but a more global understanding of the roles of miRNAs in sexual differentiation is still needed. To this end, we performed miRNA expression profiling in chicken gonads at embryonic day 5.5 (E5.5). Among the sex-biased miRNAs validated by qRT-PCR, twelve male-biased and six female-biased miRNAs were consistent with the sequencing results. Bioinformatics analysis revealed that some sex-biased miRNAs were potentially involved in gonadal development. Further functional analysis found that over-expression of miR-107 directly inhibited nuclear receptor subfamily 5 group A member 1 (NR5a1), and its downstream cytochrome P450 family 19 subfamily A, polypeptide 1 (CYP19A1). However, anti-Mullerian hormone (AMH) was not directly or indirectly regulated by miR-107. Overall results indicate that miR-107 may specifically mediate avian ovary-development by post-transcriptional regulation of NR5a1 and CYP19A1 in estrogen signaling pathways.

Gene changes may minimize masculinizing and defeminizing influences of exposure to male cotwins in female callitrichine primates

BACKGROUND

Sexual differentiation in female mammals can be altered by the proximity of male littermates in utero, a phenomenon known as the intrauterine position effect (IUP). Among simian primates, callitrichines (marmosets and tamarins) are likely candidates for IUP, since they exhibit obligate dizygotic twinning and fetuses share extensive vascularization in utero. In this paper, we determined whether female reproductive parameters are altered by gestating with a male twin and evaluated changes in genes associated with anti-Müllerian and steroid hormones in twinning callitrichine primates.

METHODS

We assessed the impact of gestation with male cotwins on reproductive performance and survivorship in female marmosets (Callithrix) and lion tamarins (Leontopithecus), contrasting measures for females gestated with one or more littermates (M+) or no male littermates (0M). We compared targeted coding regions for genes involved in steroidal and anti-Müllerian hormone mediation of sexual differentiation for representatives of twinning callitrichines (Callithrix, Saguinus, and Leontopithecus) with closely related New World primates that produce single births (Saimiri and Callimico).

RESULTS

IUP effects in females were absent in female callitrichine primates: age at first ovulation, average litter size, and the proportion of stillborn infants, and lifetime survivorship did not differ between M+ and 0M females. We documented multiple nonsynonymous substitutions in genes associated with steroid synthesis, transport, and cellular action (SRD5A2, CYP19A1, SHBG, and AR) and with anti-Müllerian hormone (AMH and AMHR2) in callitrichines. In the only callitrichine to produce single infants (Callimico), two genes contained nonsynonymous substitutions relative to twinning callitrichines (CYP19A1 and AMRHR2); these substitutions were identical with nontwinning Saimiri and humans, suggesting a reversion to an ancestral sequence.

CONCLUSIONS

In spite of a shared placental vasculature with opposite-sex twins throughout embryonic and fetal development, female callitrichine primates gestated with a male cotwin exhibit no decrement in reproductive performance relative to females gestated with female cotwins. Hence, IUP effects on female reproduction in callitrichines are modest. We have identified mutations in candidate genes relevant for steroid hormone signaling and metabolism, and especially in AMH-related genes, that are likely to alter protein structure and function in the callitrichines. These mutations may confer protection for females from the masculinizing and defeminizing influences of gestating with a male cotwin.

Expression analysis of Sox9 genes during annual reproductive cycles in gonads and after nanodelivery of LHRH in Clarias batrachus

Transcription factor Sox9 plays a crucial role in determining the fate of several cell types and is a primary factor in regulation of gonadal development. Present study reports full-length cDNA sequence of Sox9a gene and partial coding sequence (cds) of Sox9b (two duplicate orthologs of Sox9 gene) from Clarias batrachus. The coding region of Sox9a gene encoded a peptide of 460 amino acids. The partial cds of Sox9b with the length of 558bp was amplified that codes for 186 amino acids. Quantitative Real-time PCR (qRT-PCR) analysis revealed that Sox9a and Sox9b mRNA expression was significantly higher in gonads and brain tissues. Furthermore Sox9a and Sox9b mRNA expression levels were high during preparatory and pre-spawning phases and decreased gradually with onset of spawning and post-spawning phases of reproductive cycles in gonads. Chitosan nanoconjugated sLHRH (CsLHRH) of particle size 133.0nm and zeta potential of 34.3mV were synthesized and evaluated against naked sLHRH (salmon luteinizing hormone-releasing hormone). The entrapment efficiency of CsLHRH was 63%. CsLHRH nanoparticles increased the expression level of Sox9 transcripts in gonads and steroid hormonal levels in blood of male and female. Thus, our findings clearly indicate that Sox9 genes play essential role during seasonal variation of gonads. Besides, the current study reports that sustained release delivery-system will be helpful for proper gonadal development of fish. To the best of our knowledge, till date no study has been reported on nanodelivery of sLHRH and their effect on reproductive gene expression in fish.

Anti-Müllerian Hormone Is a Marker for Chemotherapy-Induced Testicular Toxicity

Due to increased numbers of young cancer patients and improved survival, the impact of anticancer treatments on fertility has become a major health concern. Despite mounting research on ovarian toxicity, there is paucity of data regarding reliable biomarkers of testicular toxicity. Our aim was to evaluate anti-Müllerian hormone (AMH) as a marker for chemotherapy-induced testicular toxicity. Serum AMH and a panel of gonadal hormones were measured in male cancer patients at baseline and after chemotherapy. In the preclinical setting, mice were injected with diverse chemotherapies and were killed 1 week or 1, 3, or 6 months later. We evaluated spermatogenesis by AMH as well as qualitative and quantitative sperm parameters. Nineteen patients were enrolled, the median age was 38 years (21-44 y). Serum AMH was correlated with increased FSH and T and decreased inhibin-B in gonadotoxic protocols (cisplatin or busulfan) and remained unchanged in nongonadotoxic protocols (capecitabine). AMH expression had the same pattern in mice serum and testes; it was negatively correlated with testicular/epididymal weight and sperm motility. The increase in testicular AMH expression was also correlated with elevated apoptosis (terminal transferase-mediated deoxyuridine 5-triphosphate nick-end labeling) and reduced proliferation (Ki67, proliferating cell nuclear antigen; all seminiferous tubules cells were analyzed). Severely damaged mice testes demonstrated a marked costaining of AMH and GATA-4, a Sertoli cell marker; staining that resembled the pattern of the Sertoli cell-only condition. Our study indicates that the pattern of serum AMH expression, in combination with other hormones, can delineate testicular damage, as determined in both experimental settings. Future large-scale clinical studies are warranted to further define the role of AMH as a biomarker for testicular toxicity.

The versatile functions of Sox9 in development, stem cells, and human diseases

The transcription factor Sox9 was first discovered in patients with campomelic dysplasia, a haploinsufficiency disorder with skeletal deformities caused by dysregulation of Sox9 expression during chondrogenesis. Since then, its role as a cell fate determiner during embryonic development has been well characterized; Sox9 expression differentiates cells derived from all three germ layers into a large variety of specialized tissues and organs. However, recent data has shown that ectoderm- and endoderm-derived tissues continue to express Sox9 in mature organs and stem cell pools, suggesting its role in cell maintenance and specification during adult life. The versatility of Sox9 may be explained by a combination of post-transcriptional modifications, binding partners, and the tissue type in which it is expressed. Considering its importance during both development and adult life, it follows that dysregulation of Sox9 has been implicated in various congenital and acquired diseases, including fibrosis and cancer. This review provides a summary of the various roles of Sox9 in cell fate specification, stem cell biology, and related human diseases. Ultimately, understanding the mechanisms that regulate Sox9 will be crucial for developing effective therapies to treat disease caused by stem cell dysregulation or even reverse organ damage.

Mini-puberty and true puberty: differences in testicular function

The ontogeny of the hypothalamic-pituitary-gonadal axis is particularly characterised by incomplete functional maturation in utero and during early postnatal life, followed by functional regression and partial quiescence during childhood, and subsequently by final complete maturation during puberty. This review addresses the distinctive features of testis developmental physiology--especially in the seminiferous tubule compartment--which explain the differences observed in testicular function and its disorders between the early postnatal activation period--which many authors call "mini-puberty"--and canonical puberty.

Spreading the clinical window for diagnosing fetal-onset hypogonadism in boys

In early fetal development, the testis secretes - independent of pituitary gonadotropins - androgens and anti-Müllerian hormone (AMH) that are essential for male sex differentiation. In the second half of fetal life, the hypothalamic-pituitary axis gains control of testicular hormone secretion. Follicle-stimulating hormone (FSH) controls Sertoli cell proliferation, responsible for testis volume increase and AMH and inhibin B secretion, whereas luteinizing hormone (LH) regulates Leydig cell androgen and INSL3 secretion, involved in the growth and trophism of male external genitalia and in testis descent. This differential regulation of testicular function between early and late fetal periods underlies the distinct clinical presentations of fetal-onset hypogonadism in the newborn male: primary hypogonadism results in ambiguous or female genitalia when early fetal-onset, whereas it becomes clinically undistinguishable from central hypogonadism when established later in fetal life. The assessment of the hypothalamic-pituitary-gonadal axis in male has classically relied on the measurement of gonadotropin and testosterone levels in serum. These hormone levels normally decline 3-6 months after birth, thus constraining the clinical evaluation window for diagnosing male hypogonadism. The advent of new markers of gonadal function has spread this clinical window beyond the first 6 months of life. In this review, we discuss the advantages and limitations of old and new markers used for the functional assessment of the hypothalamic-pituitary-testicular axis in boys suspected of fetal-onset hypogonadism.

Sox9-related signaling controls zebrafish juvenile ovary-testis transformation

In almost all vertebrates, the downstream of the sox9 signaling axis is well conserved for testis differentiation. The upstream genes of this pathway vary from species to species during evolution. Yet, little is known about how these signaling cascades are regulated and what cellular processes are dominant in ovary–testis transformation in juvenile zebrafish. In this study, we find that the transforming gonads undergo activation of sox9a-expressing stromal cells with increased deposition of extracellular matrix and formation of degenerative compartments. This leads to follicle disassembly, oocyte degeneration, follicle cell-cyp19a1a-amh conversions, and, eventually, formation of the testis cord. In vitro primary culture of juvenile ovary tissue in gonadotropins increases cytoplasmic accumulation of sox9a and p-Erk1/2, and induces mesenchymal morphology. MAPK inhibitors (MKI), a mixture of PD98059 and U0216, eliminate the cytoplasmic distribution but do not eradicate nuclear localization of sox9a and p-Erk1/2. Nuclear p53 are relatively increased in MKI-treated cells that exhibit less spreading and reduced proliferation. Despite uniform nuclear condensation, only a fraction of cells displayed the apoptotic phenotype. These results suggest that high levels of cytoplasmic sox9a and p-Erk1/2 activity activate stromal cells and enhance the production of extracellular matrix required for testis cord formation, whereas deregulation and translocation of sox9a and p-Erk1/2 induce follicle disassembly and incomplete apoptosis associated with nuclear p53. Together with the established FSH/cAMP/MAPK/AMH pathway in mammalian granulosa and Sertoli cells, we demonstrated that the sox9 axis signaling that determines testis formation in mammals also induces zebrafish ovary–testis transition, and adds to its conserved role in sex reversal.