DAX-1 inhibits SF-1-mediated transactivation via a carboxy-terminal domain that is deleted in adrenal hypoplasia congenita

Identification of MEF2A, MEF2C, and MEF2D interactomes in basal and Fsk-stimulated mouse MA-10 Leydig cells

BACKGROUND

Myocyte enhancer factor 2 transcription factors regulate essential transcriptional programs in various cell types. The activity of myocyte enhancer factor 2 factors is modulated through interactions with cofactors, chromatin remodelers, and other regulatory proteins, which are dependent on cell context and physiological state. In steroidogenic Leydig cells, MEF2A, MEF2C, and MEF2D are key regulators of genes involved in steroid hormone synthesis, reproductive function, and oxidative stress defense. However, the specific network of myocyte enhancer factor 2-interacting proteins in Leydig cells remains unknown.

OBJECTIVE

To identify the interactome of each MEF2 factor present in Leydig cells.

MATERIALS AND METHODS

TurboID proximity-mediated biotinylation combined with mass spectrometry and bioinformatic analyses were used to identify the protein‒protein interaction networks of MEF2A, MEF2C, and MEF2D in MA-10 Leydig cells under basal and stimulated conditions.

RESULTS

We identified 109 potential myocyte enhancer factor 2-interacting proteins, including some previously known myocyte enhancer factor 2 partners. The interactome for each myocyte enhancer factor 2 factor is dynamic and exhibits unique and shared interaction networks between basal and stimulated conditions. Further analysis through Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment categorized these interactions, revealing involvement in pathways related to cellular metabolism, transcriptional regulation, and steroidogenesis.

DISCUSSION AND CONCLUSION

These findings suggest that myocyte enhancer factor 2 factors can participate in diverse transcriptional activities, capable of gene activation or repression, depending on different protein‒protein interactions. In addition, the differential interactome for each myocyte enhancer factor 2 factor suggests unique regulatory roles for each factor in modulating Leydig cell function. Overall, this study provides new mechanistic insights into myocyte enhancer factor 2 action in Leydig cells by identifying interacting partners that likely influence their functions.

NR5A1 and cell population heterogeneity: Insights into developmental and functional disparities and regulatory mechanisms

Background

NR5A1 plays essential roles in the development of various tissues, including the ventromedial hypothalamus, pituitary gonadotrope, adrenal cortex, spleen, testis, and ovary. Additionally, NR5A1-positive cells in these tissues exhibit developmental and functional heterogeneity.

Methods

This review summarizes recent knowledge on the relationships between physiological functions and gene cascades regulated by NR5A1 in each tissue. In addition, we also present several intriguing examples of disparities in Nr5a1 gene regulation within the same tissues, which are relevant to developmentally and functionally heterogeneous cell populations.

Main Findings

The adrenal cortex and testicular Leydig cells exhibit clear biphasic developmental processes, resulting in functionally distinct fetal and adult cell populations in which Nr5a1 is regulated by distinct enhancers. Similar heterogeneity of cell populations has been suggested in other tissues. However, functional differences in each cell population remain unclear, and Nr5a1 gene regulation disparities have not been reported.

Conclusion

Some steroidogenic tissues demonstrate biphasic development, with fetal and adult cell populations playing distinct and crucial physiological roles. Nr5a1 regulation varies across cell populations, and analyses of gene cascades centered on NR5A1 will aid in understanding the mechanisms underlying the development and maturation of reproductive capabilities.

An integrated single-cell analysis of human adrenal cortex development

The adrenal glands synthesize and release essential steroid hormones such as cortisol and aldosterone, but many aspects of human adrenal gland development are not well understood. Here, we combined single-cell and bulk RNA sequencing, spatial transcriptomics, IHC, and micro-focus computed tomography to investigate key aspects of adrenal development in the first 20 weeks of gestation. We demonstrate rapid adrenal growth and vascularization, with more cell division in the outer definitive zone (DZ). Steroidogenic pathways favored androgen synthesis in the central fetal zone, but DZ capacity to synthesize cortisol and aldosterone developed with time. Core transcriptional regulators were identified, with localized expression of HOPX (also known as Hop homeobox/homeobox-only protein) in the DZ. Potential ligand-receptor interactions between mesenchyme and adrenal cortex were seen (e.g., RSPO3/LGR4). Growth-promoting imprinted genes were enriched in the developing cortex (e.g., IGF2, PEG3). These findings reveal aspects of human adrenal development and have clinical implications for understanding primary adrenal insufficiency and related postnatal adrenal disorders, such as adrenal tumor development, steroid disorders, and neonatal stress.

Steroidogenic Factor 1, a Goldilocks Transcription Factor from Adrenocortical Organogenesis to Malignancy

Steroidogenic factor-1 (SF-1, also termed Ad4BP; NR5A1 in the official nomenclature) is a nuclear receptor transcription factor that plays a crucial role in the regulation of adrenal and gonadal development, function and maintenance. In addition to its classical role in regulating the expression of P450 steroid hydroxylases and other steroidogenic genes, involvement in other key processes such as cell survival/proliferation and cytoskeleton dynamics have also been highlighted for SF-1. SF-1 has a restricted pattern of expression, being expressed along the hypothalamic-pituitary axis and in steroidogenic organs since the time of their establishment. Reduced SF-1 expression affects proper gonadal and adrenal organogenesis and function. On the other hand, SF-1 overexpression is found in adrenocortical carcinoma and represents a prognostic marker for patients' survival. This review is focused on the current knowledge about SF-1 and the crucial importance of its dosage for adrenal gland development and function, from its involvement in adrenal cortex formation to tumorigenesis. Overall, data converge towards SF-1 being a key player in the complex network of transcriptional regulation within the adrenal gland in a dosage-dependent manner.

Brain nuclear receptors and cardiovascular function

Brain-heart interaction has raised up increasing attentions. Nuclear receptors (NRs) are abundantly expressed in the brain, and emerging evidence indicates that a number of these brain NRs regulate multiple aspects of cardiovascular diseases (CVDs), including hypertension, heart failure, atherosclerosis, etc. In this review, we will elaborate recent findings that have established the physiological relevance of brain NRs in the context of cardiovascular function. In addition, we will discuss the currently available evidence regarding the distinct neuronal populations that respond to brain NRs in the cardiovascular control. These findings suggest connections between cardiac control and brain dynamics through NR signaling, which may lead to novel tools for the treatment of pathological changes in the CVDs.

Future directions for adrenal insufficiency: cellular transplantation and genetic therapies

Primary adrenal insufficiency occurs in 1 in 5-7000 adults. Leading aetiologies are autoimmune adrenalitis in adults and congenital adrenal hyperplasia (CAH) in children. Oral replacement of cortisol is lifesaving, but poor quality of life, repeated adrenal crises and dosing uncertainty related to lack of a validated biomarker for glucocorticoid sufficiency, persists. Adrenocortical cell therapy and gene therapy may obviate many of the shortcomings of adrenal hormone replacement. Physiological cortisol secretion regulated by pituitary adrenocorticotropin, could be achieved through allogeneic adrenocortical cell transplantation, production of adrenal-like steroidogenic cells from either stem cells or lineage conversion of differentiated cells, or for CAH, gene therapy to replace or repair a defective gene. The adrenal cortex is a high turnover organ and thus failure to incorporate progenitor cells within a transplant will ultimately result in graft exhaustion. Identification of adrenocortical progenitor cells is equally important in gene therapy where new genetic material must be specifically integrated into the genome of progenitors to ensure a durable effect. Delivery of gene editing machinery and a donor template, allowing targeted correction of the 21-hydroxylase gene, has the potential to achieve this. This review describes advances in adrenal cell transplants and gene therapy that may allow physiological cortisol production for children and adults with primary adrenal insufficiency.

Integration of RNAi and RNA-seq uncovers the regulation mechanism of DDX20 on vitellogenin expression in Scylla paramamosain

Vitellogenesis in crustaceans is controlled by several steroid hormones. In humans, the expression of SF-1, a gene that regulates gonadal development and the synthesis of steroid hormones, is affected by DDX20. However, how the homologous gene FTZ-F1 is regulated by DDX20 and its association with vitellogenesis remains unknown in the mud crab Scylla paramamosain. In this study, SpDDX20 and SpFTZ-F1 were identified in the transcriptome of mature ovarian tissue from the mud crab. qRT-PCR results revealed that the expression levels of SpFTZ-F1 and SpVTG in the ovaries of crab in the experimental group injected with dsDDX20 (EO) were significantly higher (P < 0.05) than those in the negative control group injected with dsEGFP (NO) and the blank control group injected with SPSS (BO). The differentially expressed genes (DEGs) identified by comparative transcriptome analysis of the EO group and NO group were enriched into five pathways related to ovarian steroidogenesis. The expression of CYP17, CYP3A4, CYP1A1 and 3β-HSD were up-regulated in pathways related to steroid hormone production and biosynthesis. The expression of the INSR, IRS and PI3K genes in the insulin signaling pathway were significantly increased (P < 0.05). The expression level of the TGF-β gene was up-regulated (P < 0.05) in the transforming growth factor pathway, whereas the expression level of the Smad2 gene was down-regulated (P < 0.05). The expression of GnRHR, GS, AC and PKA genes in the gonadotropin-releasing hormone signaling pathway were up-regulated. Our data provide a foundation for investigating the relationship between DDX20 and FTZ-F1 in the regulation of vitellogenin expression in S. paramamosain.

Heat stress upregulates aromatases expression through nuclear DAX-1 deficiency in R2C Leydig tumor cells

An appropriate balance between testicular testosterone and estradiol is required for spermatogenesis. Excess estradiol is often identified in the semen and serum of infertile men; however, the mechanisms behind this observation remain unclear. This study indicates the relationship between heat stress and aromatase synthesis in Leydig cells. We used R2C rat Leydig tumor cells, which can synthesize both testosterone and estradiol. Aromatase transcription was regulated by the PⅡ promoter with or without heat stress. Heat stress at 40 °C increased aromatase expression and decreased testosterone to estradiol ratio and nuclear DAX-1 (dosage-sensitive sex reversal, adrenal hypoplasia critical region, on chromosome X, gene 1), which is a suppressor of steroidogenic factor 1 (SF-1). Leptomycin B and KPT-185, a nuclear export inhibitor, prevented nuclear DAX-1 deficiency induced by heat stress and inhibited aromatase transcription. These results indicate that heat stress interferes with DAX-1-SF-1 interaction and induces SF-1-dependent aromatase transcription.

Origin, specification and differentiation of a rare supporting-like lineage in the developing mouse gonad

Gonadal sex determination represents a unique model for studying cell fate decisions. However, a complete understanding of the different cell lineages forming the developing testis and ovary remains elusive. Here, we investigated the origin, specification, and subsequent sex-specific differentiation of a previously uncharacterized population of supporting-like cells (SLCs) in the developing mouse gonads. The SLC lineage is closely related to the coelomic epithelium and specified as early as E10.5, making it the first somatic lineage to be specified in the bipotential gonad. SLC progenitors are localized within the genital ridge at the interface with the mesonephros and initially coexpress Wnt4 and Sox9. SLCs become sexually dimorphic around E12.5, progressively acquire a more Sertoli- or pregranulosa-like identity and contribute to the formation of the rete testis and rete ovarii. Last, we found that WNT4 is a crucial regulator of the SLC lineage and is required for normal development of the rete testis.

Inhibition of NR5A1 phosphorylation alleviates a transcriptional suppression defect caused by a novel NR0B1 mutation

Context

Mutations in the NR0B1 gene, also well-known as the DAX1 gene, are known to cause congenital adrenal hypoplasia associated with hypogonadotropic hypogonadism. The abnormal NR0B1 protein fails to suppress the transcription of promoters of steroidogenic enzymes, which are also targets of NR5A1 protein, also well-known as Ad4BP/SF-1 protein. Since NR5A1 and NR0B1 have antagonistic effects on steroidogenesis, the loss of function due to NR0B1 mutations may be compensated by inducing loss of function of NR5A1 protein.

Patient

A middle-aged man was diagnosed with congenital adrenal hypoplasia associated with hypogonadotropic hypogonadism and genetic analysis revealed him to have a novel NR0B1 mutation, c.1222C>T(p.Gln408Ter).

Methods

NR0B1 activity was evaluated in CLK1/4 inhibitor-treated 293T cells via immunoblotting and luciferase assays of the STAR promoter.

Results

TG003 treatment suppressed NR5A1 protein function to compensate for the mutant NR0B1 showing inhibited suppression of transcription. Immunoblotting analyses showed that the phosphorylation status of NR5A1 at Ser203 was attenuated by the CLK1/4 inhibitor.

Conclusion

The specific reduction of NR5A1 phosphorylation by a CLK1/4 inhibitor may alleviate developmental defects in patients with NR0B1 mutations.

Case Report: A Novel Truncating Variant of NR0B1 Presented With X-Linked Late-Onset Adrenal Hypoplasia Congenita With Hypogonadotropic Hypogonadism

Nuclear receptor subfamily 0 group B member 1 gene (NR0B1) encodes an orphan nuclear receptor that plays a critical role in the development and regulation of the adrenal gland and hypothalamic-pituitary-gonadal axis. In this study, we report a novel mutation in NR0B1 that led to adult-onset adrenal hypoplasia congenita (AHC) and pubertal development failure in a male adult. Clinical examinations revealed hyponatremia, elevated adrenocorticotropic hormone levels, reduced testosterone and gonadotropin levels, and hyper-responses to gonadotropin-releasing hormone and human chorionic gonadotropin stimulation tests. Whole-exome sequencing and Sanger sequencing were performed to identify the potential causes of AHC. Candidate variants were shortlisted based on the X-linked recessive models. Sequence analyses identified a novel hemizygous variant of c.1034delC in exon 1 of NR0B1 at Xp21.2, resulting in a frameshift mutation and premature stop codon formation. The c.1034delC/p.Pro345Argfs*27 in the NR0B1 gene was detected in the hemizygous state in affected males and in the heterozygous state in healthy female family carriers. These results expand the clinical features of AHC as well as the mutation profile of the causative gene NR0B1. Further studies are needed to elucidate the biological effects of the mutation on the development and function of the adrenal gland and the hypothalamic-pituitary-gonadal axis.

Hamster DAX1: Molecular insights, specific expression, and its role in the Harderian gland

DAX1 plays an essential role in the differentiation and physiology of the Hypothalamic-Pituitary-Adrenal-Gonadal (HPAG) axis during embryogenesis. However, in adult tissues, in addition to the HPAG axis, evidence has not been found for its differential expression and function. We isolated the DAX1 cDNA to analyze its tissue localization and gene expression profiles in male and female hamsters' Harderian glands (HGs), Mesocricetus auratus. The isolated cDNA clone contains 1848 base pairs (bp), and a 1428-bp open reading frame (ORF) encodes a 476 amino acid protein. Sequence alignments and the phylogenetic tree display a relevant percentage of similarity with human (66%), rat (81%), and mouse (84%) sequences. In adult tissues, the mRNA distribution demonstrated that DAX1 is present in testis, ovaries, and male and female HGs. The highest expression profiles were identified in the adrenal glands, where females exhibit higher mRNA levels than males. The sexually dimorphic expression of DAX1 in adrenals suggests that its presence could be associated with regulating, functioning, and maintaining this endocrine tissue. These findings indicate that the DAX1 gene is limitedly expressed in adult tissues. In the HGs, we demonstrate the absence of sexually dimorphic gene expression. Our results suggest that DAX1 might have an additional physiological function outside of the HPAG axis, specifically in the HG, which may be required for the regulation of intracrine steroidogenesis, secretion, and maintenance of exocrine tissue.

Nonsense variant of NR0B1 causes hormone disorders associated with congenital adrenal hyperplasia

Congenital adrenal hyperplasia (CAH) is a rare X-linked recessive inherited disease that is considered a major cause of steroidogenesis disorder and is associated with variants or complete deletion of the NR0B1 gene. The DAX-1 protein (encoded by NR0B1) is a vertebrate-specific orphan nuclear receptor and is also a transcriptional factor for adrenal and reproductive development. CAH usually causes adrenal insufficiency in infancy and early childhood, leading to hypogonadotropic hypogonadism in adulthood; however, few adult cases have been reported to date. In this study, we examined a Chinese family with one adult patient with CAH, and identified a putative variant of NR0B1 gene via next-generation sequencing (NGS), which was confirmed with Sanger sequencing. A novel nonsense variant (c.265C>T) was identified in the NR0B1 gene, which caused the premature termination of DAX-1 at residue 89 (p.G89*). Furthermore, mutant NR0B1 gene displayed a partial DAX-1 function, which may explain the late pathogenesis in our case. Additionally, qPCR revealed the abnormal expression of four important genes identified from ChIP-seq, which were associated with energy homeostasis and steroidogenesis, and were influenced by the DAX-1 mutant. In addition, hormone disorders can be caused by DAX-1 mutant and partially recovered by siRNA of PPARGC1A. Herein, we identified a novel nonsense variant (c.265C>T) of NR0B1 in a 24-year-old Chinese male who was suffering from CAH. This mutant DAX-1 protein was found to have disordered energy homeostasis and steroidogenesis based on in vitro studies, which was clinically consistent with the patient’s phenotypic features.

Adrenal cortex renewal in health and disease

Resident progenitor and/or stem cell populations in the adult adrenal cortex enable cortical cells to undergo homeostatic renewal and regeneration after injury. Renewal occurs predominantly in the outer layers of the adrenal gland but newly formed cells undergo centripetal migration, differentiation and lineage conversion in the process of forming the different functional steroidogenic zones. Over the past 10 years, advances in the genetic characterization of adrenal diseases and studies of mouse models with altered adrenal phenotypes have helped to elucidate the molecular pathways that regulate adrenal tissue renewal, several of which are fine-tuned via complex paracrine and endocrine influences. Moreover, the adrenal gland is a sexually dimorphic organ, and testicular androgens have inhibitory effects on cell proliferation and progenitor cell recruitment in the adrenal cortex. This Review integrates these advances, including the emerging role of sex hormones, into existing knowledge on adrenocortical cell renewal. An in-depth understanding of these mechanisms is expected to contribute to the development of novel therapies for severe endocrine diseases, for which current treatments are unsatisfactory.

A novel stop-loss DAX1 variant affecting its protein-interaction with SF1 precedes the adrenal hypoplasia congenital with rare spontaneous precocious puberty and elevated hypothalamic-pituitary-gonadal/adrenal axis responses

The case study unveils the likely mechanism of a novel stop-loss DAX1 variant preceding the prolonged precocious puberty in the adrenal hypoplasia congenital (AHC) boy. A boy aged five years and nine months initially examined for the primary adrenal insufficiency symptoms. Next-generation sequencing confirmed the X-linked inheritance of a novel stop-loss DAX1 variant: c.1411T>C/p.Ter471Gln associated with AHC in the patient. The patient was subjected to a brief clinical follow-up from 11 to 15.1 years of age. The effect of the mutant-DAX1 variant (p.Ter471Gln) on DAX1-steroidogenic factor 1 (SF1) (protein-protein) interaction was studied by protein-protein docking using the ClusPro-online tool. At 5.9 yrs of age, the patient exhibited precocious puberty with the secondary sexual characteristics of Tanner 2 stage (of 9-14 yrs of age). The patient showed primary adrenal insufficiency with diminished cortisol concentrations at blood serum (25 ng/ml) and urine (3.55 μg/24 h) levels. Upon steroidal exposure, the patient showed normalized serum cortisol levels of 45-61 ng/ml. However, the precocious puberty got prolonged with the increased penis length of 8.5 cm and the bone age of 18 yrs old during the follow-up. The patient showed increased basal serum adrenocorticotropic hormone (110->2000 pg/ml) and follicle-stimulating hormone (18.4-22.3 mIU/ml) concentrations. Following an elevated hypothalamic-pituitary-gonadal axis activity witnessed upon gonarellin stimulation. Protein-protein docking confirmed a weaker interaction between the mutant-DAX1 (p.Ter471Gln) protein and the wild-SF1 protein. Overall, we hypothesize the weakened mutant-DAX1-SF1 (protein-protein) interaction could govern the prolonged precocious puberty augmented with the elevated hypothalamic-pituitary-gonadal/adrenal axis responses via SF1-induced neuronal nitric oxide synthetase activation in the patient.

Identification and Analysis of a Novel NR0B1 Mutation in Late-Onset Adrenal Hypoplasia Congenita and Hypogonadism

Objective

X-linked adrenal hypoplasia congenita (AHC) is a rare disorder characterized by primary adrenal insufficiency and hypogonadotropic hypogonadism (HHG) caused by mutations of the NR0B1/DAX1 gene. We aimed to search for the presence of any NR0B1/DAX1 gene mutations in a referred patient and to further characterize the phenotypes of the identified mutation.

Case Presentation

Herein, we report a Japanese patient with a novel missense mutation of the NR0B1/DAX1 gene resulting in adult-onset AHC and HHG. The patient was referred with diffuse skin pigmentation at 28 years of age, presented partial adrenal insufficiency and had undiagnosed incomplete HHG. Urological examination revealed severe oligospermia and testicular microlithiasis.

Results

The NR0B1/DAX1 gene mutation was identified by exome sequencing as a novel missense mutation (c.884A>T, p.Leu295His). We conducted in silico modeling of this mutant NR0B1/DAX1 protein (p.Leu295His) which affected the conserved hydrophobic core of the putative ligand-binding domain (LBD). In addition, functional analysis revealed that this mutant showed a decreased ability as a transcriptional repressor to suppress target genes, such as STAR and LHB. Furthermore, this mutant showed functionally impaired repression of steroidogenesis in human adrenocortical H295R cells.

Conclusions

We identified a novel missense mutation of the NR0B1/DAX1 gene in a patient suffering from late-onset AHC and HHG, who presented with oligospermia and testicular microlithiasis. This mutant NR0B1/DAX1 protein was found to have reduced repressor activity, according to in vitro studies, clinically consistent with the patient’s phenotypic features.

Novel NR5A1 Pathogenic Variants Cause Phenotypic Heterogeneity in 46,XY Disorders of Sex Development

Steroidogenic factor 1 (NR5A1/SF1) is a key transcription factor that is known to regulate the development of adrenal glands and gonads and is also involved in steroidogenesis. Several pathogenic NR5A1 variants have been reported to cause 46,XY disorders of sex development (DSD), with varying clinical phenotypes ranging from hypospadias to complete gonadal dysgenesis. Most often, the primary cause of DSD is due to variants in gene(s) related to gonadal development or the steroidogenic pathway. In the present study, we have analyzed 64 cases of 46,XY DSD for pathogenic NR5A1 variants. We report a total of 3 pathogenic variants of which 2 were novel (p.Gly22Ser and p.Ser143Asn) and 1 was already known (p.Ser32Asn). Functional studies have revealed that the 2 mutations p.Gly22Ser and p.Ser32Asn could significantly affect DNA binding and transactivation abilities. Further, these mutant proteins showed nuclear localization with aggregate formation. The third mutation, p.Ser143Asn, showed unspeckled nuclear localization and normal DNA binding, but the ability of transcriptional activation was significantly reduced. In conclusion, we recommend screening for NR5A1 pathogenic variants in individuals with features of 46,XY DSD for better diagnosis and management.

Retinoic Acid Antagonizes Testis Development in Mice

Mammalian sex determination depends on a complex interplay of signals that promote the bipotential fetal gonad to develop as either a testis or an ovary, but the details are incompletely understood. Here, we investigated whether removal of the signaling molecule retinoic acid (RA) by the degradative enzyme CYP26B1 is necessary for proper development of somatic cells of the testes. Gonadal organ culture experiments suggested that RA promotes expression of some ovarian markers and suppresses expression of some testicular markers, acting downstream of Sox9. XY Cyp26b1-null embryos, in which endogenous RA is not degraded, develop mild ovotestes, but more important, steroidogenesis is impaired and the reproductive tract feminized. Experiments involving purified gonadal cells showed that these effects are independent of germ cells and suggest the direct involvement of the orphan nuclear receptor DAX1. Our results reveal that active removal of endogenous RA is required for normal testis development in the mouse.

Roles of two cyp11 genes in sex hormone biosynthesis in Japanese flounder (Paralichthys olivaceus)

The P450 side-chain cleavage enzymes P450scc (Cyp11a) and 11β-hydroxylase (Cyp11b) play important roles in sex steroid and cortisol production. Here, two duplicates of cyp11 genes were identified in Japanese flounder (Paralichthys olivaceus): Pocyp11a and Pocyp11b, respectively. Phylogenetic analysis and amino acid sequence alignment revealed that Pocyp11a and Pocyp11b shared significant identity with sequences of other teleost fish species. The quantitative real-time polymerase chain reaction (qRT-PCR) results indicated that among the studied tissues, brain tissue showed the highest expression of Pocyp11a, followed by kidney and testis tissues, whereas Pocyp11b expression was highest in the testis. The expression patterns of these two genes showed sexual dimorphism, with both genes showing higher expression in the testis than in the ovary. In-situ hybridization analysis demonstrated that Pocyp11a and Pocyp11b mRNA were both detected in oocytes, spermatocytes, and Sertoli cells, indicating that they might be involved in hormone synthesis. The expression levels of Pocyp11a and Pocyp11b were significantly downregulated by treatment with 17α-methyltestosterone (17α-MT) in the testis and ovary in both in vivo and studies. In vivo studies showed that Pocyp11a and Pocyp11b transcripts were suppressed by 17β-estradiol (E₂ ) treatment in both the testis and ovary. In addition, in vitro studies showed that the expression level of Pocyp11b was decreased by treatment with E₂ , whereas that of Pocyp11a was largely unaffected. Moreover, the expression levels of Pocyp11a and Pocyp11b in the testis cell line were significantly upregulated after NR0b1 and NR5a2 (p < .05) treatment. These results indicate that Pocyp11a and Pocyp11b might play important roles in sex hormone biosynthesis. Our research can assist future studies of the mechanisms of steroid biosynthesis and functional differences between cyp11a and cyp11b in Japanese flounder.

Prenatal glucocorticoids exposure and fetal adrenal developmental programming

Clinically, we apply synthetic glucocorticoids to treat fetal and maternal diseases, such as premature labor and autoimmune diseases. Although its clinical efficacy is positive, the fetus will be exposed to exogenous synthetic glucocorticoids. Prenatal adverse environments (such as xenobiotics exposure, malnutrition, infection, hypoxia and stress) can cause fetuses overexposure to excessive endogenous maternal glucocorticoids. The level of glucocorticoids is the key to fetal tissue maturation and postnatal fate. A large number of studies have found that prenatal glucocorticoids exposure can lead to fetal adrenal dysplasia and dysfunction, continuing after birth and even into adulthood. As the core organ of fetal-originated adult diseases, fetal adrenal dysplasia is closely related to the susceptibility and occurrence of multiple chronic diseases, and there are also obvious gender differences. However, its intrauterine programming mechanisms have not been fully elucidated. This review summarizes recent advances in prenatal glucocorticoids exposure and fetal adrenal developmental programming alterations, which is of great significance for explaining adrenal developmental toxicity and the intrauterine origin of fetal-originated adult diseases.

Novel mutations and spectrum of the disease of NR0B1 (DAX1)-related adrenal insufficiency in Indian children

Background X-linked adrenal hypoplasia congenita (AHC), due to mutations in the nuclear receptor superfamily 0, group B, member 1 (NR0B1)/dosage-sensitive sex reversal, AHC, critical region on the X chromosome, gene 1 (DAX1) gene, usually presents with a salt-wasting adrenal crisis in infancy and hypogonadotropic hypogonadism (HH) in adolescents. Genetic reports in the literature from patients of diverse ethnicity are limited. We describe the atypical clinical characteristics and molecular genetic results in six Indian patients. Methods Both exons and flanking intronic sequences of the NR0B1 gene were amplified and sequenced in five patients. In the sixth patient, suspected to have a large deletion, multiplex ligation-dependent probe amplification (MLPA) and chromosomal microarray analysis were performed. Results Sequencing revealed three novel mutations: a nonsense mutation (c.776C > A), a deletion (c.298del), both causing loss of domains which are highly conserved among nuclear receptor families, and a missense mutation (c.1112T > C). In-silico analysis by structure-based protein modeling predicted a de-stabilizing effect of the novel missense mutation. Two previously reported mutations were seen in patients with atypical manifestations such as late-onset adrenal insufficiency and precocious puberty. One patient had a 7.15-Mb contiguous deletion involving the NR0B1, Duchenne muscular dystrophy (DMD), glycerol kinase (GK) and melanoma antigen, family B, 16 (MAGEB16) genes. Conclusions Our report emphasizes the wide clinical spectrum of AHC, including rare manifestations, and enumerates unique mutations in the NR0B1 gene.

Novel frameshift mutation of the NR0B1(DAX1) in two tall adult brothers

NR0B1 (nuclear receptor subfamily 0, group B, member 1) is a transcription factor encoded by DAX1 (dosage-sensitive sex reversal, adrenal hypoplasia critical region, on chromosome X, gene 1) responsible for the development and maintenance of the steroidogenic tissues. In humans the DAX1 mutations cause congenital adrenal hypoplasia (AHC) and hypogonadotropic hypogonadism (HHG) in boys. Here we report two brothers who were assessed by endocrinologist at the age of 51 and 43 because of their serious osteoporosis. They had been substituted with prednisolone since the age of 4 and 9 years because of their primary adrenal insufficiency (PAI). Due to their late puberty caused by HHG at the age of 16 and 17 years their heights were - 3.1 and - 3.3 SD, but then they had a significant growth during their adulthood and reached the + 1.85 SD and + 3.78 SD respectively. During this period, they received glucocorticoid supplementation, but the treatment of their HHG was inadequate. At the age of 51 and 43 years insulin tolerance test (ITT) and gonadotropin releasing hormone (GnRH) test confirmed their PAI and HHG. Genetic test performed at this time revealed a novel, four nucleotides deletion (del.586-571c.GGGC or 572-575c.GGGC) of DAX1 gene. The two brothers with AHC and HHG caused by a novel DAX1 mutation, reached tall final heights, despite of the disadvantageous prednisolone treatment during their childhood. We assume that the long-term lack of the sexual hormone substitution was a significant reason of their above average height as well as their serious osteoporosis.

Gene dosage of DAX-1, determining in sexual differentiation: duplication of DAX-1 in two sisters with gonadal dysgenesis

Two sisters phenotypically normal females, presenting with tumor abdominal mass with histopathological findings of teratoma and gonadoblastoma associated to 46,XY male-to-female sex reversal syndrome, secondary to a duplication in DAX-1, possibly inherited of maternal gonadal mosaicism. Copy number variation and functional effects of the duplication were done by MLPA multiplex ligation-dependent probe amplification and real time PCR. DAX-1, also known as dosage sensitive sex reversal gene (DSS), is considered the most likely candidate gene involved in XY gonadal dysgenesis when overexpressed. The excess of DAX-1 gene disturbs testicular development by down regulation of SF-1, WT1, and SOX9. This is the first report of 46,XY sex reversal in two siblings who have a maternally inherited duplication of DAX-1 associated with reduced levels of expression of downstream genes as SOX9-SF1.

Identification and Functional Analysis of Six DAX1 Mutations in Patients With X-Linked Adrenal Hypoplasia Congenita

Context

DAX1 (NR0B1) mutations cause X-linked adrenal hypoplasia congenita (AHC) and hypogonadotropic hypogonadism (HH) in affected male patients. Affected individuals typically present with early-onset adrenal insufficiency and develop HH during puberty. Rare cases can present with late-onset adrenal insufficiency or other unusual phenotypes.

Objectives

We sought to identify and functionally characterize DAX1 mutations in seven Thai male subjects in six families with X-linked AHC.

Patients and Methods

Six patients had classic phenotypes with early-onset adrenal failure. One patient presented with late-onset Addison disease at 17 years. In the early-onset group, one patient had GnRH-independent sexual precocity at 3 years of age, and another patient had growth hormone deficiency. The DAX1 gene was sequenced from all patients, and the transcriptional activities of the identified mutations were assessed in vitro using luciferase assays.

Results

DAX1 mutations were identified in all patients, including three novel mutations [c.363delG (p.Gly122Valfs*142), c.1062delC (p.Ala355Profs*17), and c.1156C>T (p.Leu386Phe)] and three known mutations [c.1148_1149delGG (p.Gly383Aspfs*5), c.501_502insG (p.Ala170Argfs*15), and c.805_807delGTC (p.Val269del)]. Functional studies showed that the DAX1 mutants had lower levels of repressor activity on the StAR gene promoter compared with the wild-type DAX-1 protein.

Conclusions

This study describes unusual phenotypes and three novel mutations, extending the phenotypic and mutational spectra of DAX1 mutations.

Sex chromosomes-linked single-gene disorders involved in human infertility

Human infertility is a healthcare problem that has a worldwide impact. Genetic causes of human infertility include chromosomal aneuploidies and rearrangements and single-gene defects. The sex chromosomes (X and Y) are critical players in human fertility since they contain several genes essential for sex determination and reproductive traits for both men and women. This paper provides a review of the most common sex chromosomes-linked single-gene disorders involved in human infertility and their corresponding phenotypes. In addition to the Y-linked SRY gene, which mutations may cause XY gonadal dysgenesis and sex reversal, the deletions of genes present in AZF regions of the Y chromosome (DAZ, RBMY, DBY and USP9Y genes) are implicated in varying degrees of spermatogenic dysfunction. Furthermore, a list of X-linked genes (KAL1, NR0B1, AR, TEX11, FMR1, PGRMC1, BMP15 and POF1 and 2 regions genes (XPNPEP2, POF1B, DACH2, CHM and DIAPH2)) were reported to have critical roles in pubertal and reproductive deficiencies in humans, affecting only men, only women or both sexes. Mutations in these genes may be transmitted to the offspring by a dominant or a recessive inheritance.

Human fetal adrenal cells retain age-related stem- and endocrine-differentiation potential in culture

The adrenal gland is a multiendocrine organ with a steroidogenic mesenchymal cortex and an inner catecholamine-producing medulla of neuroendocrine origin. After embryonic development, this plastic organ undergoes a functional postnatal remodeling. Elucidating these complex processes is pivotal for understanding the early bases of functional endocrine disorders and tumors affecting the mature gland. We developed an in vitro human adrenal cell model derived from fetal adrenal specimens at different gestational ages, consisting of neuroendocrine and cortical components and expressing the zona and functional markers of the original fetal organ. These cortical and neuroendocrine progenitor cells retain in vitro an intrinsic gestational-age-related differentiation and functional program. In vitro these cells spontaneously form 3-dimensional structure organoids with a structure similar to the fetal gland. The organoids show morphofunctional features and adrenal steroidogenic factor, steroid acute regulatory, cytochrome-P450-17A1, dosage-sensitive, sex-reversal, adrenal hypoplasia-critical region on chromosome X protein , NOTCH1, and nephroblastoma overexpressed/cysteine-rich protein 61/connective tissue growth factor/nephroblastoma overexpressed gene-3; stem (BMI1, nestin); and chromaffin (chromogranin A, tyrosine hydroxylase) markers similar to those of the populations of origin. This in vitro human adrenal system represents a unique but preliminar model for investigating the pathophysiological processes underlying physiologic adrenal remodeling and pathologic alterations involved in organ hypo- and hyperplasia and cancer.-Poli, G., Sarchielli, E., Guasti, D., Benvenuti, S., Ballerini, L., Mazzanti, B., Armignacco, R., Cantini, G., Lulli, M., Chortis, V., Arlt, W., Romagnoli, P., Vannelli, G. B., Mannelli, M., Luconi, M. Human fetal adrenal cells retain age-related stem- and endocrine-differentiation potential in culture.

Cloning, characterization and function analysis of DAX1 in Chinese loach (Paramisgurnus dabryanus)

The mechanisms of sex determination and differentiation have not been elucidated in most fish species. In this study, the full-length cDNAs of DAX1 was cloned and characterized in aquaculture fish Chinese loach (Paramisgurnus dabryanus), designated as Pd-DAX1. The cDNA sequence of Pd-DAX1 was 1261 bp, including 795 bp open reading frame (ORF) encoding 264 amino acids. Pd-DAX1 shares highly identical sequence with DAX1 homologues from different species. The expression profiles of Pd-DAX1 in different developmental stages and diverse adult tissues were analyzed by quantitative real-time RT-PCR and in situ hybridization (ISH). Pd-DAX1 was continuously expressed during embryogenesis, with the extensive distribution in the development of the central nervous system. Tissue distribution analysis revealed that Pd-DAX1 expressed widely in adult tissues, with the highest expression level found in testis, moderate level in ovary, showing a sex-dimorphic expression pattern. Pd-DAX1 mainly located in spermatogonia cells, spermatocytes, primary oocytes and previtellogenic oocyte cells, implying that Pd-DAX1 may involve in gametogenesis. These preliminary findings suggest that Pd-DAX1 gene is highly conserved during vertebrate evolution and involved in a wide range of developmental processes including embryogenesis, central nervous system development and gonad development.

Characteristics of Cyp11a during Gonad Differentiation of the Olive Flounder Paralichthys olivaceus

The P450 side-chain cleavage enzyme, P450scc (Cyp11a) catalyzes the first enzymatic step for the synthesis of all steroid hormones in fish. To study its roles in gonads of the olive flounder Paralichthys olivaceus, an important maricultured fish species, we isolated the cyp11a genomic DNA sequence of 1396 bp, which consists of 5 exons and 4 introns. Semi-quantitative reverse transcription polymerase chain reaction (RT-PCR) results indicated that the flounder cyp11a was exclusively expressed in gonad and head kidney tissues. Its expression level in the testis was higher than that in the ovary. According to the in situ hybridization patterns, cyp11a was mainly expressed in the Leydig cells of the testis, and the thecal cells of the ovary. Immunofluorescence analysis showed that Cyp11a was located in the cytoplasm of the cultured flounder testis cells. Further quantitative real-time PCR results presented the cyp11a differential expression patterns during gonad differentiation. Among different sampling points of the 17β-estradiol (E2, 5 ppm) treatment group, cyp11a expression levels were relatively high in the differentiating ovary (30 and 40 mm total length, TL), and then significantly decreased in the differentiated ovary (80, 100 and 120 mm TL, p < 0.05). The pregnenolone level also dropped in the differentiated ovary. In the high temperature treatment group (HT group, 28 ± 0.5 °C), the cyp11a expression level fluctuated remarkably in the differentiating testis (60 mm TL), and then decreased in the differentiated testis (80, 100 mm TL, p < 0.05). In the testosterone (T, 5 ppm) treatment group, the cyp11a was expressed highly in undifferentiated gonads and the differentiating testis, and then dropped in the differentiated testis. Moreover, the levels of cholesterol and pregnenolone of the differentiating testis in the HT and T groups increased. The expression level of cyp11a was significantly down-regulated after the cultured flounder testis cells were treated with 75 and 150 μM cyclic adenosine monophosphate (cAMP), respectively (p < 0.05), and significantly up-regulated after treatment with 300 μM cAMP (p < 0.05). Both nuclear receptors NR5a2 and NR0b1 could significantly up-regulate the cyp11a gene expression in a dosage dependent way in the testis cells detected by cell transfection analysis (p < 0.05). The above data provides evidence that cyp11a would be involved in the flounder gonad differentiation and development.

The human adrenal cortex: growth control and disorders

This review summarizes key knowledge regarding the development, growth, and growth disorders of the adrenal cortex from a molecular perspective. The adrenal gland consists of two distinct regions: the cortex and the medulla. During embryological development and transition to the adult adrenal gland, the adrenal cortex acquires three different structural and functional zones. Significant progress has been made in understanding the signaling and molecules involved during adrenal cortex zonation. Equally significant is the knowledge obtained regarding the action of peptide factors involved in the maintenance of zonation of the adrenal cortex, such as peptides derived from proopiomelanocortin processing, adrenocorticotropin and N-terminal proopiomelanocortin. Findings regarding the development, maintenance and growth of the adrenal cortex and the molecular factors involved has improved the scientific understanding of disorders that affect adrenal cortex growth. Hypoplasia, hyperplasia and adrenocortical tumors, including adult and pediatric adrenocortical adenomas and carcinomas, are described together with findings regarding molecular and pathway alterations. Comprehensive genomic analyses of adrenocortical tumors have shown gene expression profiles associated with malignancy as well as methylation alterations and the involvement of miRNAs. These findings provide a new perspective on the diagnosis, therapeutic possibilities and prognosis of adrenocortical disorders.

Current knowledge on the acute regulation of steroidogenesis

How rapid induction of steroid hormone biosynthesis occurs in response to trophic hormone stimulation of steroidogenic cells has been a subject of intensive investigation for approximately six decades. A key observation made very early was that acute regulation of steroid biosynthesis required swift and timely synthesis of a new protein whose role appeared to be involved in the delivery of the substrate for all steroid hormones, cholesterol, from the outer to the inner mitochondrial membrane where the process of steroidogenesis begins. It was quickly learned that this transfer of cholesterol to the inner mitochondrial membrane was the regulated and rate-limiting step in steroidogenesis. Following this observation, the quest for this putative regulator protein(s) began in earnest in the late 1950s. This review provides a history of this quest, the candidate proteins that arose over the years and facts surrounding their rise or decline. Only two have persisted-translocator protein (TSPO) and the steroidogenic acute regulatory protein (StAR). We present a detailed summary of the work that has been published for each of these two proteins, the specific data that has appeared in support of their role in cholesterol transport and steroidogenesis, and the ensuing observations that have arisen in recent years that have refuted the role of TSPO in this process. We believe that the only viable candidate that has been shown to be indispensable is the StAR protein. Lastly, we provide our view on what may be the most important questions concerning the acute regulation of steroidogenesis that need to be asked in future.

Insulin Regulates Adrenal Steroidogenesis by Stabilizing SF-1 Activity

Development of metabolic syndrome is associated with hyperactivity of the HPA axis characterized by elevated levels of circulating adrenal hormones including cortisol and aldosterone. However, the molecular mechanism leading to the dysregulation of the HPA axis is not well elucidated. In this study, we found that insulin regulates adrenal steroidogenesis by increasing the expression and activity of steroidogenic factor 1 (SF-1) both in vitro and in vivo and this insulin effect was partly through inhibition of FoxO1. Specifically, insulin increased the protein and RNA levels of SF-1 and steroidogenic target genes. Further, adrenal SF-1 expression was significantly increased by hyperactivation of insulin signaling in mice. Together with the elevated SF-1 expression in adrenal glands, hyperactivation of insulin signaling led to increased aldosterone and corticosterone levels. On the other hand, suppressing the insulin signaling using streptozotocin markedly reduced the expression of adrenal SF-1 in mice. In addition, overexpression of FoxO1 significantly suppressed SF-1 and its steroidogenic target genes implying that the positive effect of insulin on SF-1 activity might be through suppression of FoxO1 in the adrenal gland. Taken together, these results indicate that insulin regulates adrenal steroidogenesis through coordinated control of SF-1 and FoxO1.

Molecular mechanism of mercury-induced reproductive impairments in banded gourami, Trichogaster fasciata

Mercury is one of the key pollutants responsible for the degradation of natural aquatic ecosystems. Among the different forms of mercury that exist in the environment, mercuric chloride (HgCl₂) is the dominant pollutant for freshwater environments as it is used as an ingredient in antiseptics, disinfectants and preservatives, insecticides, batteries and in metallurgical and photographic operations. Pollutant may exert their action on organisms or populations by affecting their normal endocrine function as well as reproduction. Thus, the present study tried to understand the effect of mercuric chloride (HgCl₂) on reproductive function and to decipher the molecular mechanism of Hg-induced reproductive impairments of female Trichogaster fasciata. Both in vivo and in vitro experiments were performed by using ecologically relevant doses of HgCl₂ and the resulting effects on follicular development, steroidogenic potentiality, aromatase activity, aromatase gene expression and steroidogenic factor-1 (SF-1) expression pattern were analysed. In vivo exposure to HgCl₂ caused reproductive impairments as shown by the inhibitory role of HgCl₂ on follicular development, steroid biosynthesis and SF-1 activity. In vitro experiments revealed that aromatase activity, steroidogenesis, aromatase and SF-1 expression were blocked by HgCl₂. The results obtained from this study contribute to understand the molecular mechanism of HgCl₂-induced reproductive impairment of T. fasciata.

Late-onset X-linked adrenal hypoplasia (DAX-1, NR0B1): two new adult-onset cases from a single center

PURPOSE

DAX-1 (NR0B1) is an orphan nuclear receptor, which plays a critical role in development and regulation of the adrenal gland and hypothalamo-pituitary-gonadal axis. Mutations in NR0B1 lead to adrenal hypoplasia congenita (AHC), hypogonadotropic hypogonadism (HH) and azoospermia in men. Presentation is typically with adrenal insufficiency (AI) during infancy or childhood. To date only eight cases/kindreds are reported to have presented in adulthood.

METHODS

We describe two new cases of men with DAX-1 mutations who presented in adulthood and who were diagnosed at a large University Hospital.

RESULTS

Case 1 presented with AI at 19 years. At 38 years he was diagnosed with HH. Detailed history revealed a brother diagnosed with AI at a similar age. Sequencing of the DAX-1 (NR0B1) gene revealed a heterozygous c.775T > C substitution in exon 1, which changes codon 259 from serine to proline (p.Ser259Pro). Case 2 was diagnosed with AI at 30 years. Aged 37 years he presented with HH and azoospermia. He was treated with gonadotropin therapy but remained azoospermic. Testicular biopsy showed maturational arrest and hypospermatogenesis. Analysis of the NR0B1 gene showed a heterozygous c.836C > T substitution in exon 1, resulting in a change of codon 279 from proline to leucine (p.Pro279Leu). This change alters the structure of the repression helix domain of DAX-1 and affects protein complex interactions with NR5A family members.

CONCLUSIONS

We describe two missense mutations within the putative carboxyl-terminal ligand binding domain of DAX-1, presenting with AHC and HH in adulthood, from a single center. DAX-1 mutations may be more frequent in adults than previously recognized. We recommend testing for DAX-1 mutations in all adults with primary AI and HH or impaired fertility where the etiology is unclear.

Leydig progenitor cells in fetal testis

Testicular Leydig cells play pivotal roles in masculinization of organisms by producing androgens. At least two distinct Leydig cell populations sequentially emerge in the mammalian testis. Leydig cells in the fetal testis (fetal Leydig cells) appear just after initial sex differentiation and induce masculinization of male fetuses. Although there has been a debate on the fate of fetal Leydig cells in the postnatal testis, it has been generally believed that fetal Leydig cells regress and are completely replaced by another Leydig cell population, adult Leydig cells. Recent studies revealed that gene expression patterns are different between fetal and adult Leydig cells and that the androgens produced in fetal Leydig cells are different from those in adult Leydig cells in mice. Although these results suggested that fetal and adult Leydig cells have distinct origins, several recent studies of mouse models support the hypothesis that fetal and adult Leydig cells arise from a common progenitor pool. In this review, we first provide an overview of previous knowledge, mainly from mouse studies, focusing on the cellular origins of fetal Leydig cells and the regulatory mechanisms underlying fetal Leydig cell differentiation. In addition, we will briefly discuss the functional differences of fetal Leydig cells between human and rodents. We will also discuss recent studies with mouse models that give clues for understanding how the progenitor cells in the fetal testis are subsequently destined to become fetal or adult Leydig cells.

MANAGEMENT OF ENDOCRINE DISEASE: Regenerative therapies in autoimmune Addison's disease

The treatment for autoimmune Addison's disease (AAD) has remained virtually unchanged in the last 60 years. Most patients have symptoms that are relatively well controlled with exogenous steroid replacement, but there may be persistent symptoms, recurrent adrenal crisis and poor quality of life, despite good compliance with optimal current treatments. Treatment with conventional exogenous steroid therapy is also associated with premature mortality, increased cardiovascular risk and complications related to excessive steroid replacement. Hence, novel therapeutic approaches have emerged in the last decade attempting to improve the long-term outcome and quality of life of patients with AAD. This review discusses the recent developments in treatment innovations for AAD, including the novel exogenous steroid formulations with the intention of mimicking the physiological biorhythm of cortisol secretion. Our group has also carried out a few studies attempting to restore endogenous glucocorticoid production via immunomodulatory and regenerative medicine approaches. The recent advances in the understanding of adrenocortical stem cell biology, and adrenal plasticity will also be discussed to help comprehend the science behind the therapeutic approaches adopted.

Molecular Mechanisms of Stem/Progenitor Cell Maintenance in the Adrenal Cortex

The adrenal cortex is characterized by three histologically and functionally distinct zones: the outermost zona glomerulosa (zG), the intermediate zona fasciculata, and the innermost zona reticularis. Important aspects of the physiology and maintenance of the adrenocortical stem/progenitor cells have emerged in the last few years. Studies have shown that the adrenocortical cells descend from a pool of progenitors that are localized in the subcapsular region of the zG. These cells continually undergo a process of centripetal displacement and differentiation, which is orchestrated by several paracrine and endocrine cues, including the pituitary-derived adrenocorticotrophic hormone, and angiotensin II. However, while several roles of the endocrine axes on adrenocortical function are well established, the mechanisms coordinating the maintenance of an undifferentiated progenitor cell pool with self-renewal capacity are poorly understood. Local factors, such as the composition of the extracellular matrix (ECM) with embedded signaling molecules, and the activity of major paracrine effectors, including ligands of the sonic hedgehog and Wnt signaling pathways, are thought to play a major role. Particularly, the composition of the ECM, which exhibits substantial differences within each of the three histologically distinct concentric zones, has been shown to influence the differentiation status of adrenocortical cells. New data from other organ systems and different experimental paradigms strongly support the conclusion that the interactions of ECM components with cell-surface receptors and secreted factors are key determinants of cell fate. In this review, we summarize established and emerging data on the paracrine and autocrine regulatory loops that regulate the biology of the progenitor cell niche and propose a role for bioengineered ECM models in further elucidating this biology in the adrenal.

FOXL2 Is an Essential Activator of SF-1-Induced Transcriptional Regulation of Anti-Müllerian Hormone in Human Granulosa Cells

Anti-Müllerian hormone (AMH) is required for proper sexual differentiation by regulating the regression of the Müllerian ducts in males. Recent studies indicate that AMH could be an important factor for maintaining the ovarian reserve. However, the mechanisms of AMH regulation in the ovary are largely unknown. Here, we provide evidence that AMH is an ovarian target gene of steroidogenic factor-1 (SF-1), an orphan nuclear receptor required for proper follicle development. FOXL2 is an evolutionally conserved transcription factor, and its mutations cause blepharophimosis, ptosis, and epicanthus inversus syndrome (BPES), wherein affected females display eyelid defects and premature ovarian failure (POF). Notably, we found that functional FOXL2 is essential for SF-1-induced AMH regulation, via protein-protein interactions between FOXL2 and SF-1. A BPES-inducing mutant of FOXL2 (290-291delCA) was unable to interact with SF-1 and failed to mediate the association between SF-1 and the AMH promoter. Therefore, this study identified a novel regulatory circuit for ovarian AMH production; specifically, through the coordinated interplay between FOXL2 and SF-1 that could control ovarian follicle development.

Identification of NR0B1 as a novel androgen receptor co-repressor in mouse Sertoli cells

Nuclear receptor subfamily 0 group B member 1 (Nr0b1) is an atypical member of the nuclear receptor family that is predominantly expressed in mouse Sertoli cells (SCs). Mutations of NR0B1 in humans cause adrenal failure and hypogonadotropic hypogonadism. The targeted mutagenesis of Nr0b1 in mice has revealed a primary gonadal defect characterized by the overexpression of aromatase and cellular obstruction of the seminiferous tubules and efferent ductules, leading to germ cell death and infertility. The transgenic expression of Nr0b1 under the control of the Müllerian-inhibiting substance promoter (MIS-Nr0b1), which is selectively expressed in SCs, improves fertility. Testicular androgen receptor (AR) was also expressed in SCs. Many genes are directly regulated by androgen and its AR, which are involved in spermatogenesis and male infertility. As the association between NR0B1 and AR remains unclear in mouse SCs, we decided to further explore the relationship between them. In the present study, we have identified NR0B1 as a novel AR co-repressor in mouse SCs. Using RT‑qPCR and immunofluorescence, we determined that NR0B1 was mainly expressed in mouse SCs in an age-dependent manner from 2-8 weeks of age postnatally. The inhibition of the effects of AR on AR target genes by NR0B1, in an androgen‑dependent manner, was further demonstrated by western blot analysis and RT-qPCR in TM4 cells, a mouse Sertoli cell line. Finally, in vitro luciferase and co-immunoprecipitation assays validated that NR0B1, as an AR co-repressor, significantly inhibited the transcriptional activation of its target genes. These results suggest that novel inhibitory mechanisms underlie the effects of NR0B1 in modulating androgen-dependent gene transcription in mouse SCs.

Functional Zonation of the Adult Mammalian Adrenal Cortex

The standard model of adrenocortical zonation holds that the three main zones, glomerulosa, fasciculata, and reticularis each have a distinct function, producing mineralocorticoids (in fact just aldosterone), glucocorticoids, and androgens respectively. Moreover, each zone has its specific mechanism of regulation, though ACTH has actions throughout. Finally, the cells of the cortex originate from a stem cell population in the outer cortex or capsule, and migrate centripetally, changing their phenotype as they progress through the zones. Recent progress in understanding the development of the gland and the distribution of steroidogenic enzymes, trophic hormone receptors, and other factors suggests that this model needs refinement. Firstly, proliferation can take place throughout the gland, and although the stem cells are certainly located in the periphery, zonal replenishment can take place within zones. Perhaps more importantly, neither the distribution of enzymes nor receptors suggest that the individual zones are necessarily autonomous in their production of steroid. This is particularly true of the glomerulosa, which does not seem to have the full suite of enzymes required for aldosterone biosynthesis. Nor, in the rat anyway, does it express MC2R to account for the response of aldosterone to ACTH. It is known that in development, recruitment of stem cells is stimulated by signals from within the glomerulosa. Furthermore, throughout the cortex local regulatory factors, including cytokines, catecholamines and the tissue renin-angiotensin system, modify and refine the effects of the systemic trophic factors. In these and other ways it more and more appears that the functions of the gland should be viewed as an integrated whole, greater than the sum of its component parts.

Impact of ACTH Signaling on Transcriptional Regulation of Steroidogenic Genes

The trophic peptide hormone adrenocorticotropic (ACTH) stimulates steroid hormone biosynthesis evoking both a rapid, acute response and a long-term, chronic response, via the activation of cAMP/protein kinase A (PKA) signaling. The acute response is initiated by the mobilization of cholesterol from lipid stores and its delivery to the inner mitochondrial membrane, a process that is mediated by the steroidogenic acute regulatory protein. The chronic response results in the increased coordinated transcription of genes encoding steroidogenic enzymes. ACTH binding to its cognate receptor, melanocortin 2 receptor (MC2R), stimulates adenylyl cyclase, thus inducing cAMP production, PKA activation, and phosphorylation of specific nuclear factors, which bind to target promoters and facilitate coactivator protein recruitment to direct steroidogenic gene transcription. This review provides a general view of the transcriptional control exerted by the ACTH/cAMP system on the expression of genes encoding for steroidogenic enzymes in the adrenal cortex. Special emphasis will be given to the transcription factors required to mediate ACTH-dependent transcription of steroidogenic genes.

X-linked adrenal hypoplasia congenita and hypogonadotropic hypogonadism: Identification and in vitro study of a novel small indel in the NR0B1 gene

DAX1 is an orphan nuclear receptor that has a key role in the development and function of the adrenal and reproductive axes. Mutations in NR0B1, the gene encoding DAX1, result in X-linked adrenal hypoplasia congenita (AHC) and hypogonadotropic hypogonadism (HHG). A Chinese pedigree with X-linked AHC and HHG was investigated in the present study. Sequence analysis identified a novel small indel variant, c.195_207delinsTG, in the NR0B1 gene. To determine the effect of this variant on DAX1 expression, reverse‑transcription quantitative PCR and western blot assays were performed. The mRNA expression levels in carriers of mutant NR0B1 were significantly reduced (62% decrease) compared to those in individuals with wild-type NR0B1 (WT). The c.195_207delinsTG mutation was demonstrated to lead to various truncated DAX1 proteins, including the C‑terminal truncated DAX1, which was only detected in the cytoplasm, and the N‑terminal truncated DAX1, which was present in the cytoplasm and nucleus. A luciferase assay was then performed to assess the repressor function of DAX1 in modulating steroidogenic factor 1 (SF‑1)‑mediated transactivation. WT DAX1 significantly suppressed the SF‑1‑mediated promoter activity of the steroidogenic acute regulatory protein by 35.5±1.9%. In contrast to other known pathogenic mutations which abolish the repressor function of DAX1, the c.195_207delinsTG mutant proxkduced a higher repressor activity, demonstrating a 49.9±2.6% reduction of promoter activity. These findings suggested that the mutation of NR0B1 in X‑linked AHC with HHG enhanced the function of DAX1 to repress SF-1 activation, while DAX1 is expected to have additional roles in the pathological mechanism.

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.

Clinical and molecular genetic analysis of a Chinese family with congenital X-linked adrenal hypoplasia caused by novel mutation 1268delA in the DAX-1 gene

Congenital X-linked adrenal hypoplasia (AHC) is a rare disease characterized by primary adrenal insufficiency before adolescence and by hypogonadotropic hypogonadism (HHG) during adolescence. In this paper, we present a Chinese family with AHC. Two brothers, misdiagnosed with adrenal insufficiency of unknown etiology at the age of 9, were correctly diagnosed with AHC when delayed puberty, HHG, and testicular defects were observed. We investigated the clinical features and identified the dosage-sensitive sex reversal AHC critical region of the X chromosome gene 1 (DAX-1) mutation in this kindred. Direct sequencing of the DAX-1 gene revealed that the two siblings have a novel mutation (1268delA) of which their mother is a heterozygous carrier. This mutation causes a frameshift and a premature stop codon at position 436, encoding a truncated protein. It is important to increase knowledge of the mutational spectrum in genes related to this disease, linking phenotype to genotype.

Fgfr2 is required for the expansion of the early adrenocortical primordium

The adrenal cortex is a critical steroidogenic endocrine tissue, generated at least in part from intermediate mesoderm of the anterior urogenital ridge. Previous work has pinpointed a minor role of the FGFR2IIIb isoform in expansion and differentiation of the fetal adrenal cortex in mice but did not address the complete role of FGFR2 and FGFR1 signaling in adrenocortical development. Here, we show that a Tbx18(cre) line mediates specific recombination in the coelomic epithelium of the anterior urogenital ridge which gives rise by a delamination process to the adrenocortical primordium. Mice with conditional (Tbx18(cre)-mediated) deletion of all isoforms of Fgfr2 exhibited severely hypoplastic adrenal glands around birth. Cortical cells were dramatically reduced in number but showed steroidogenic differentiation and zonation. Neuroendocrine chromaffin cells were also reduced and formed a cell cluster adjacent to but not encapsulated by steroidogenic cells. Analysis of earlier time points revealed that the adrenocortical primordium was established in the intermediate mesoderm at E10.5 but that it failed to expand at subsequent stages. Our further experiments show that FGFR2 signaling acts as early as E11.5 to prevent apoptosis and enhance proliferation in adrenocortical progenitor cells. FGFR1 signaling does not contribute to early adrenocortical development. Our work suggests that FGFR2IIIb and IIIc isoforms largely act redundantly to promote expansion of the adrenocortical primordium.

DAX-1 (NR0B1) and steroidogenic factor-1 (SF-1, NR5A1) in human disease

DAX-1 (NR0B1) and SF-1 (NR5A1) are two nuclear receptor transcription factors that play a key role in human adrenal and reproductive development. Loss of DAX-1 function is classically associated with X-linked adrenal hypoplasia congenita. This condition typically affects boys and presents as primary adrenal insufficiency in early infancy or childhood, hypogonadotropic hypogonadism at puberty and impaired spermatogenesis. Late onset forms of this condition and variant phenotypes are increasingly recognized. In contrast, disruption of SF-1 only rarely causes adrenal insufficiency, usually in combination with testicular dysgenesis. Variants in SF-1/NR5A1 more commonly cause a spectrum of reproductive phenotypes ranging from 46,XY DSD (partial testicular dysgenesis or reduced androgen production) and hypospadias to male factor infertility or primary ovarian insufficiency. Making a specific diagnosis of DAX-1 or SF-1 associated conditions is important for long-term monitoring of endocrine and reproductive function, appropriate genetic counselling for family members, and for providing appropriate informed support for young people.

A Novel Mutation of DAX-1 Associated with Secretory Azoospermia

Secretory azoospermia is a severe form of male infertility caused by unknown factors. DAX-1 is predominantly expressed in mammalian reproductive tissues and plays an important role in spermatogenesis because Dax-1 knockout male mice show spermatogenesis defects. To examine whether DAX-1 is involved in the pathogenesis of secretory azoospermia in humans, we sequenced all of the exons of DAX-1 in 776 patients diagnosed with secretory azoospermia and 709 proven fertile men. A number of coding mutations unique to the patient group, including two synonymous mutations and six missense mutations, were identified. Of the missense mutations, our functional assay demonstrated that the V385L mutation caused the reduced functioning of DAX-1. This novel mutation (p. V385L) of DAX-1 is the first to be identified in association with secretory azoospermia, thereby highlighting the important role of DAX-1 in spermatogenesis.

Notch signaling represses GATA4-induced expression of genes involved in steroid biosynthesis

Notch2 and Notch3 and genes of the Notch signaling network are dynamically expressed in developing follicles, where they are essential for granulosa cell proliferation and meiotic maturation. Notch receptors, ligands, and downstream effector genes are also expressed in testicular Leydig cells, predicting a potential role in regulating steroidogenesis. In this study, we sought to determine if Notch signaling in small follicles regulates the proliferation response of granulosa cells to FSH and represses the up-regulation steroidogenic gene expression that occurs in response to FSH as the follicle grows. Inhibition of Notch signaling in small preantral follicles led to the up-regulation of the expression of genes in the steroid biosynthetic pathway. Similarly, progesterone secretion by MA-10 Leydig cells was significantly inhibited by constitutively active Notch. Together, these data indicated that Notch signaling inhibits steroidogenesis. GATA4 has been shown to be a positive regulator of steroidogenic genes, including STAR protein, P450 aromatase, and 3B-hydroxysteroid dehydrogenase. We observed that Notch downstream effectors HEY1, HEY2, and HEYL are able to differentially regulate these GATA4-dependent promoters. These data are supported by the presence of HEY/HES binding sites in these promoters. These studies indicate that Notch signaling has a role in the complex regulation of the steroidogenic pathway.