Thromboxane A2 Modulates de novo Synthesis of Adrenal Corticosterone in Mice via p38/14-3-3γ/StAR Signaling

Prostanoids are endogenous lipid bioactive mediators that play essential roles in physiological processes such as glucocorticoid secretion. Here, it is found that the thromboxane (Tx)A2 receptor (TP) is highly expressed in the adrenal cortex of mice. Both global and adrenocortical-specific deletion of the TP receptor lead to increased adiposity in mice by elevating corticosterone synthesis. Mechanistically, the TP receptor deletion increases the phosphorylation of steroidogenic acute regulatory protein (StAR) and corticosterone synthesis in adrenal cortical cells by suppressing p-p38-mediated phosphorylation of 14-3-3γ adapter protein at S71. The activation of the p38 in the adrenal cortical cells by forced expression of the MKK6EE gene attenuates hypercortisolism in TP-deficient mice. These observations suggest that the TxA2/TP signaling regulates adrenal corticosterone homeostasis independent of the hypothalamic-pituitary-adrenal axis and the TP receptor may serve as a promising therapeutic target for hypercortisolism.

Breed Differences in Serum Testosterone Levels of Male Pigs Are Highly Correlated with Differences in Testicular mRNA Levels of Enzymes and Proteins Involved in Testosterone Biosynthesis Process

To clarify the causes of breed differences in serum testosterone levels of male pigs, which affect the mRNA expression of drug metabolizing enzymes and drug transporters in the liver and kidney, we focused on testicular enzymes and proteins involved in testosterone biosynthesis process and comparatively examined their mRNA levels by real time RT-PCR among low serum testosterone-type Landrace pigs and high serum testosterone-type Meishan and Landrace/Meishan-crossbreed (LM and ML) pigs. Testicular mRNA levels of the enzymes (3-hydroxy-3-methylglutaryl-CoA synthase 1 and 3-hydroxy-3-methylglutaryl-CoA reductase) and proteins (low density lipoprotein receptor and scavenger receptor class B member 1) affecting intracellular levels of cholesterol, a precursor of testosterone, were 2-5-fold higher in Meishan, LM and ML pigs than in Landrace pigs. Likewise, the mRNA levels of steroidogenic acute regulatory protein, which imports cholesterol to the inner mitochondrial membrane, and of testosterone biosynthesis enzymes (CYP11A1 and CYP17A1) were over 10-fold and approximately 3-fold higher, respectively, in Meishan, LM and ML pigs than in Landrace pigs. Furthermore, positive correlations between those mRNA levels and serum testosterone levels were observed. Despite large breed differences in testicular mRNA levels described above, no significant breed differences in intratesticular testosterone levels were observed. The present findings strongly suggest that breed differences in serum testosterone levels of male pigs are probably, at least in part, caused by differences in testicular mRNA levels of enzymes and proteins involved in testosterone biosynthesis process and by differences in the levels of testosterone released from testes.

Mitoguardin2 Is Associated With Hyperandrogenism and Regulates Steroidogenesis in Human Ovarian Granulosa Cells

Polycystic ovary syndrome (PCOS) is an endocrinopathy characterized by hyperandrogenism, anovulation, and polycystic ovaries, in which hyperandrogenism manifests by excess androgen and other steroid hormone abnormalities. Mitochondrial fusion is essential in steroidogenesis, while the role of mitochondrial fusion in granulosa cells of hyperandrogenic PCOS patients remains unclear. In this study, mRNA expression of mitochondrial fusion genes mitoguardin1, -2 (MIGA 1, -2) was significantly increased in granulosa cells of hyperandrogenic PCOS but not PCOS with normal androgen levels, their mRNA expression positively correlated with testosterone levels. Dihydrotestosterone (DHT) treatment in mice led to high expression of MIGA2 in granulosa cells of ovulating follicles. Testosterone or forskolin/ phorbol 12-myristate 13-acetate treatments increased expression of MIGA2 and the steroidogenic acute regulatory protein (StAR) in KGN cells. MIGA2 interacted with StAR and induced StAR localization on mitochondria. Furthermore, MIGA2 overexpression significantly increased cAMP-activated protein kinase A (PKA) and phosphorylation of AMP-activated protein kinase (pAMPK) at T172 but inhibited StAR protein expression. However, MIGA2 overexpression increased CYP11A1, HSD3B2, and CYP19A1 mRNA expression. As a result, MIGA2 overexpression decreased progesterone but increased estradiol synthesis. Besides the androgen receptor, testosterone or DHT might also regulate MIGA2 and pAMPK (T172) through LH/choriogonadotropin receptor-mediated PKA signaling. Taken together, these findings indicate that testosterone regulates MIGA2 via PKA/AMP-activated protein kinase signaling in ovarian granulosa cells. It is suggested mitochondrial fusion in ovarian granulosa cells is associated with hyperandrogenism and potentially leads to abnormal steroidogenesis in PCOS.

Anthocyanins Prevent AAPH-Induced Steroidogenesis Disorder in Leydig Cells by Counteracting Oxidative Stress and StAR Abnormal Expression in a Structure-Dependent Manner

Testosterone deficiency may increase the risk of sexual dysfunction and the failure of spermatogenesis. Oxidative stress that is derived from the destruction of homeostasis, disease, and exposure to contaminants can damage the steroidogenicity process in Leydig cells, resulting in a reduction in testosterone synthesis. Anthocyanins are a group of innoxious antioxidants widely recognized in food sources, and are an ideal candidate to relieve oxidative stress-related steroidogenesis disorder. However, there is still a major gap in our knowledge of the structure-function relationship of anthocyanin on the activity mentioned above. In the present study, four anthocyanins including cyanidin-3-glucoside (Cy-3-glu), delphinidin-3-glucoside (Dp-3-glu), pelargonidin-3-glucoside (Pg-3-glu), and cyanidin-3,5-diglucoside (Cy-3,5-diglu) were applied to reverse testosterone generation after employing 2,2'-Azobis(2-amidinopropane)-dihydrochloride (AAPH) as the inducer of oxidative stress in R2C cells. The results demonstrated that all four kinds of anthocyanins can inhibit ROS generation, alleviate mitochondrial membrane potential damage, and contribute to increased testosterone. Among them, Cy-3,5-diglu with diglycoside performed best on antioxidative ability and improved cell dysfunction and upregulated the expression of the steroidogenic acute regulatory protein (StAR). The molecular docking further revealed the direct combination between anthocyanins and StAR, suggesting that anthocyanins with monosaccharide were more likely to interact with StAR than with diglycoside. Taken together, these data indicate that recipient R2C cells under oxidative stress submitted to anthocyanins exhibited improved steroidogenesis in a structure-dependent manner. Anthocyanins could be considered the ideal ingredients against oxidative stress-induced testosterone deficiency.

Interplay between polycystic ovary syndrome and hypothyroidism on serum testosterone, oxidative stress and StAR gene expression in female rats

INTRODUCTION

Endocrine disorders such as polycystic ovary syndrome (PCOS) and hypothyroidism can cause infertility. There are evidence that they happen jointly in some circumstances. It still remains unknown, how these two illnesses interact and influence the body.

METHODS

Accordingly, a five-group was designed, first is the control group, followed by the PCOS group. Estradiol valerate (EV) induced PCOS, the second group had only PCOS and the third, fourth and fifth groups were given varied dosages of propylthiouracil (PTU) to cause hypothyroidism after induction of PCOS. Steroidogenic acute regulatory protein (StAR) expression was measured in the ovaries, and serum was obtained to determine testosterone levels, as well as superoxide dismutase (SOD) as an antioxidant and malondialdehyde (MDA) as an oxidant.

RESULTS

Based on radioimmunoassay data, testosterone levels were significantly higher in the PCOS group than the control group, and significantly lower (p ˂ .05) in PTU groups comparing with the PCOS group. According to the quantitative real-time polymerase chain reaction (qRT-PCR) data, the same results were obtained for the StAR gene as well. The data also indicated a positive correlation between these two. Although both oxidant and antioxidant level increased in PCOS group compared than control group, after hypothyroidism, oxidant level increased significantly (p ˂ .05), meanwhile antioxidant level decreased significantly (p ˂ .05).

CONCLUSIONS

The results of this study illustrate that the presence of both PCOS and hypothyroidism alters the situation more than just PCOS. They also indicate that this situation is associated with imbalanced oxidative/antioxidative status.

Analysis of Activity of Human Steroidogenic Acute Regulatory Protein (STARD1) Expressed in Escherichia coli Cells

One of the main obstacles to the successful use of Escherichia coli cells for steroid transformation in biotechnological processes is inefficient transport of steroid substrates into the cells. Here, we tested the possibility of using human cholesterol transfer protein STARD1 (steroidogenic acute regulatory protein) to increase the efficiency of steroid uptake by bacterial cells. Genetic constructs were obtained for the synthesis in E. coli BL21 (DE3) cells of a truncated version of STARD1 containing protein functional domain (residues 66-285) and STARD1 (66-285)-GFP fusion protein, both carrying bacterial periplasmic targeting sequence pelB at the N-terminus. Analysis of preparations of E. coli/pET22b/STARD1-GFP cells by fluorimetry and Western blotting confirmed that the used expression system ensured the synthesis of the heterologous protein. Using fluorescence spectroscopy, it was demonstrated that the presence of STARD1 in the cells increased the efficiency of assimilation of NBD-labeled cholesterol analogues by E. coli/pET22b/STARD1 cells 1.3-1.6 times (p < 0.05) compared to the wild-type cells, thus demonstrating that human STARD1 exhibits its functional activity in bacterial cells. This opens prospects for optimizing and using a fundamentally new approach to increase the efficiency of steroid uptake by cells - the inclusion of a specific carrier protein in the cell membrane, which can expand the arsenal of methods used to obtain strains of microorganisms for synthesis.

Prenatal dexamethasone exposure programs the decreased testosterone synthesis in offspring rats by low level of endogenous glucocorticoids

Prenatal dexamethasone exposure (PDE) can decrease maternal endogenous glucocorticoid level and induce testicular dysplasia in male offspring rats. In this study we investigated low level endogenous glucocorticoid-mediated testicular dysplasia in PDE offspring and elucidated the intrauterine epigenetic programming mechanisms. Pregnant rats were injected with dexamethasone (0.2 mg·kg^-1·d^-1, sc) on gestational day (GD) 9-20. The offspring rat blood and testis were collected after euthanasia on GD20, postnatal week (PW) 12 or PW28. We showed that PDE induced abnormal morphology of testis and significantly decreased the expression of testosterone synthesis-related genes as well as testosterone production before and after birth. Meanwhile, serum corticosterone, the expression and histone 3 lysine 14 acetylation (H3K14ac) of testicular insulin-like growth factor 1 (IGF1) were significantly decreased. After the pregnant rats were subjected to chronic stress for 2 weeks (PW10-12), serum corticosterone level was increased in the adult PDE offspring, and the above-mentioned other indicators were also improved. Cultured Leydig cells (TM3) were treated with corticosterone (62.5-500 nM) in vitro. We showed that corticosterone concentration-dependently inhibited glucocorticoid receptor α (GRα) and miR-124-3p expression, increased histone deacetylase 5 (HDAC5) expression, and decreased IGF1 H3K14ac level and the expression of IGF1/steroidogenic acute regulatory protein (StAR), suggesting that corticosterone at lower than physiological level (<500 nM) inhibited testosterone synthesis by reducing H3K14ac and the expression level of IGF1 through GRα/miR-124-3p/HDAC5 pathway. In conclusion, PDE can cause persistent inhibition of testosterone synthesis before and after birth in the offspring rats by low level of endogenous glucocorticoids.

Growth Hormone-induced STAT5B Regulates Star Gene Expression Through a Cooperation With cJUN in Mouse MA-10 Leydig Cells

Leydig cells produce androgens that are essential for male sex differentiation and reproductive function. Leydig cell function is regulated by several hormones and signaling molecules, including growth hormone (GH). Although GH is known to upregulate Star gene expression in Leydig cells, its molecular mechanism of action remains unknown. The STAT5B transcription factor is a downstream effector of GH signaling in other systems. While STAT5B is present in both primary and Leydig cell lines, its function in these cells has yet to be ascertained. Here we report that treatment of MA-10 Leydig cells with GH or overexpression of STAT5B induces Star messenger RNA levels and increases steroid hormone output. The mouse Star promoter contains a consensus STAT5B element (TTCnnnGAA) at -756 bp to which STAT5B binds in vitro (electrophoretic mobility shift assay and supershift) and in vivo (chromatin immunoprecipitation) in a GH-induced manner. In functional promoter assays, STAT5B was found to activate a -980 bp mouse Star reporter. Mutating the -756 bp element prevented STAT5B binding but did not abrogate STAT5B-responsiveness. STAT5B was found to functionally cooperate with DNA-bound cJUN. The STAT5B/cJUN cooperation was only observed in Leydig cells and not in Sertoli or fibroblast cells, indicating that additional Leydig cell-enriched transcription factors are required. The STAT5B/cJUN cooperation was lost only when both STAT5B and cJUN elements were mutated. In addition to identifying the Star gene as a novel target for STAT5B in Leydig cells, our data provide important new insights into the mechanism of GH and STAT5B action in the regulation of Leydig cell function.

Clinical characteristics of a male child with non-classic lipoid congenital adrenal hyperplasia and literature review

BACKGROUND

Lipoid congenital adrenal hyperplasia (LCAH) is a rare and severe disorder that is caused by mutations in the steroidogenic acute regulatory protein (StAR). Non-classic LCAH is defined as late-onset glucocorticoid deficiency and even complete male external genitalia in 46,XY individuals. However, to date, few cases of non-classic LCAH have been reported.

METHODS

It was attempted to describe the clinical characteristics of a male child with complete male external genitalia in terms of age of onset, adrenal function, and biochemical indicators. Previously reported cases were also reviewed to investigate the relationship of age of onset with enzymatic activity in non-classic LCAH.

RESULTS

The patient with complete male external genitalia was diagnosed with non-classic LCAH, in which the reason for his referral to a local hospital at the of age 1.25 years was progressive skin hyperpigmentation, and plasma adrenocorticotropic hormone (ACTH) level was elevated to higher than 1,250 pg/ml. The compound heterozygous mutations c.772C>T/c.562C>T in STAR gene were identified via genetic testing. The literature review resulted in identification of 47 patients with non-classic LCAH from 36 families. The mutational analysis showed that c.562C>T mutation was prevalent in patients with non-classic LCAH, accounting for 37.2% of the total mutant alleles, which could reflect the founder effect on the non-classic LCAH population. In total, 28 46,XY patients were reported, including 22 (78.5%) cases with complete male external genitalia and six (21.5%) cases with different degrees of hypospadias.

CONCLUSION

The clinical phenotypes of non-classic LCAH are highly variable. Routine physical examination, laboratory measurement, genetic testing, and, importantly, enzymatic activity assay may facilitate the early diagnosis of non-classic LCAH. The age of primary adrenal insufficiency (PAI) onset may not be a diagnostic basis for non-classic LCAH, and enzymatic activity assay determination may be more effective.

Amodiaquine promotes testosterone production and de novo synthesis of cholesterol and triglycerides in Leydig cells

Testosterone is a hormone essential for male reproductive function. It is produced primarily by Leydig cells in the testicle through activation of steroidogenic acute regulatory protein and a series of steroidogenic enzymes, including a cytochrome P450 side-chain cleavage enzyme (cytochome P450 family 11 subfamily A member 1), 17α-hydroxylase (cytochrome P450 family 17 subfamily A member 1), and 3β-hydroxysteroid dehydrogenase. These steroidogenic enzymes are mainly regulated at the transcriptional level, and their expression is increased by the nuclear receptor 4A1. However, the effect on Leydig cell function of a small molecule-activating ligand, amodiaquine (AQ), is unknown. We found that AQ effectively and significantly increased testosterone production in TM3 and primary Leydig cells through enhanced expression of steroidogenic acute regulatory protein, cytochome P450 family 11 subfamily A member 1, cytochrome P450 family 17 subfamily A member 1, and 3β-hydroxysteroid dehydrogenase. Concurrently, AQ dose-dependently increased the expression of 3-hydroxy-3-methylglutaryl-CoA reductase, a key enzyme in the cholesterol synthesis pathway, through induction of the transcriptional and DNA-binding activities of nuclear receptor 4A1, contributing to increased cholesterol synthesis in Leydig cells. Furthermore, AQ increased the expression of fatty acid synthase and diacylglycerol acyltransferase and potentiated de novo synthesis of fatty acids and triglycerides (TGs). Lipidomics profiling further confirmed a significant elevation of intracellular lipid and TG levels by AQ in Leydig cells. These results demonstrated that AQ effectively promotes testosterone production and de novo synthesis of cholesterol and TG in Leydig cells, indicating that AQ may be beneficial for treating patients with Leydig cell dysfunction and subsequent testosterone deficiency.

Non-classical lipoid adrenal hyperplasia presenting as hypoglycemic seizures

Introduction Primary adrenal insufficiency is a potentially life-threatening condition that can have many underlying causes. Mutations in the steroidogenic acute regulatory protein (StAR) gene produce lipoid congenital adrenal hyperplasia (LCAH) which usually presents in the infantile period with severe symptoms of adrenal insufficiency. Less commonly, a non-classical form is identified which may present at a later age in affected individuals. Till date, around 30 individuals with the non-classical form have been described. Case presentation We describe a 4-year-old 46, XX Indian girl who presented with hypoglycemic seizures and was subsequently diagnosed as non-classical LCAH on genetic analysis, with homozygous R188C mutation in the StAR gene. Conclusions StAR mutations may have a variety of clinical presentations and are likely under-diagnosed. Genetic diagnosis is important for treatment as well as monitoring of reproductive function.

Clinical Features of 57 Patients with Lipoid Congenital Adrenal Hyperplasia: Criteria for Nonclassic Form Revisited

CONTEXT

Lipoid congenital adrenal hyperplasia (LCAH) is caused by mutations in STAR. Classic (CLCAH) and nonclassic (NCLCAH) forms were reported as total and partial deficiencies, respectively, of adrenal and gonadal steroid hormones. The rarity of LCAH has precluded large-scale epidemiological and clinical investigations.

OBJECTIVE

To determine the epidemiological and clinical characteristics of 2 forms of LCAH.

DESIGN

A multicenter cross-sectional cohort study in Japan on December 1, 2017.

PARTICIPANTS

Fifty-seven patients with LCAH (median age, 23.7 years; range, 0.0-47.5 years).

MAIN OUTCOME MEASURES

Patient demographics, STAR genotype, Quigley grade, endocrinological and imaging data, treatment, and prognosis.

RESULTS

Fifty-three and 4 patients fulfilled definite and probable diagnostic criteria for LCAH, respectively. When NCLCAH was defined as either Quigley grade 1 in XY karyotype, no episode of salt losing or requirement of fludrocortisone, or onset of primary adrenal insufficiency (PAI) at 1 year or older, patients were divided into groups of 43 patients with CLCAH (75.4%), 11 with NCLCAH (19.3%), and 3 with unclassified LCAH (5.3%). All of the patients with CLCAH and 7/11 NCLCAH (63.6%) were treated with fludrocortisone. CLCAH was diagnosed at a significantly younger age than NCLCAH (median, 0.0 vs 4.0 years). STAR-Arg272Cys or -Met225Thr was identified only in NCLCAH (8/11, 72.7%).

CONCLUSIONS

We demonstrated the relative proportions and clinical and molecular characteristics of NCLCAH and CLCAH in Japan. These criteria for NCLCAH correspond to all previously published cases and our cases whose masculinization of the external genitalia, ability of mineralocorticoid production, and onset of PAI were described.

Characterization of Two Novel Variants of the Steroidogenic Acute Regulatory Protein Identified in a Girl with Classic Lipoid Congenital Adrenal Hyperplasia

Congenital adrenal hyperplasia (CAH) consists of several autosomal recessive disorders that inhibit steroid biosynthesis. We describe a case report diagnosed with adrenal insufficiency due to low adrenal steroids and adrenocorticotropic hormone excess due to lack of cortisol negative feedback signaling to the pituary gland. Genetic work up revealed two missense variants, p.Thr204Arg and p.Leu260Arg in the STAR gene, inherited by both parents (non-consanguineous). The StAR protein supports CYP11A1 enzyme to cleave the side chain of cholesterol and synthesize pregnenolone which is metabolized to all steroid hormones. We used bioinformatics to predict the impact of the variants on StAR activity and then we performed functional tests to characterize the two novel variants. In a cell system we tested the ability of variants to support cholesterol conversion to pregnenolone and measured their mRNA and protein expression. For both variants, we observed loss of StAR function, reduced protein expression and categorized them as pathogenic variants according to guidelines of the American College of Medical Genetics and Genomics and the Association for Molecular Pathology. These results fit the phenotype of the girl during diagnosis. This study characterizes two novel variants and expands the list of missense variants that cause CAH.

RNA-seq-based identification of Star upregulation by islet amyloid formation

Aggregation of islet amyloid polypeptide (IAPP) into islet amyloid results in β-cell toxicity in human type 2 diabetes. To determine the effect of islet amyloid formation on gene expression, we performed ribonucleic acid (RNA) sequencing (RNA-seq) analysis using cultured islets from either wild-type mice (mIAPP), which are not amyloid prone, or mice that express human IAPP (hIAPP), which develop amyloid. Comparing mIAPP and hIAPP islets, 5025 genes were differentially regulated (2439 upregulated and 2586 downregulated). When considering gene sets (reactomes), 248 and 52 pathways were up- and downregulated, respectively. Of the top 100 genes upregulated under two conditions of amyloid formation, seven were common. Of these seven genes, only steroidogenic acute regulatory protein (Star) demonstrated no effect of glucose per se to modify its expression. We confirmed this differential gene expression using quantitative reverse transcription polymerase chain reaction (qRT-PCR) and also demonstrated the presence of STAR protein in islets containing amyloid. Furthermore, Star is a part of reactomes representing metabolism, metabolism of lipids, metabolism of steroid hormones, metabolism of steroids and pregnenolone biosynthesis. Thus, examining gene expression that is differentially regulated by islet amyloid has the ability to identify new molecules involved in islet physiology and pathology applicable to type 2 diabetes.

Cyclophilin D participates in the inhibitory effect of high-fat diet on the expression of steroidogenic acute regulatory protein

OBJECTIVE

The high-fat diet (HFD)-induced obesity is responsible for the testosterone deficiency (TD). However, the mechanism remains unknown. Mitochondrial homeostasis is proved to be important for maintaining the function of steroidogenic acute regulatory protein (StAR), the first rate-limiting enzyme in testosterone synthesis. As the key regulator of mitochondrial membrane permeability, cyclophilin D (CypD) plays a crucial role in maintaining mitochondrial function. In this study, we sought to elucidate the role of CypD in the expression of StAR affected by HFD.

METHODS

To analyse the influence of CypD on StAR in vivo and in vitro, mouse models of HFD, CypD overexpression and CypD knockout (Ppif-/- ) as well as Leydig cells treated with palmitic acid (PA) and CypD overexpression plasmids were examined with an array of metabolic, mitochondrial function and molecular assays.

RESULTS

Compared with the normal diet mice, consistent with reduced testosterone in testes, the expressions of StAR in both mRNA and protein levels in HFD mice were down-regulated, while expressions of CypD were up-regulated. High-fat intake impaired mitochondrial function with the decrease in StAR in Leydig cells. Overexpression of CypD inhibited StAR expressions in vivo and in vitro. Compared with C57BL/6 mice with HFD, expressions of StAR were improved in Ppif-/- mice with HFD.

CONCLUSIONS

Mitochondrial CypD involved in the inhibitory effect of HFD on StAR expression in testes.

Effect of genistein on the gene expressions of androgen generating key enzymes StAR, P450scc and CYP19 in rat ovary

In this investigation, the effects of genistein (GEN) on the expression of steroidogenic genes such as steroidogenic acute regulatory protein (StAR), side-chain cleavage enzymes (P450scc) and cytochrome P450 aromatase (CYP19) were assessed. For this study, forty young female Sprague Dawley (SD) rats at aged 2-3 months (200±20 g) and forty aged female SD rats aged 10-12 months (490±20 g) were selected. Also, based on weight they were divided into a negative control group (NC), three different GEN dose groups, which received GEN of 15, 30, 60 mg/kg, and a positive control group (PC). The experiment lasted 30 days. Concentrations of serum hormones were determined by Enzyme-linked immunosorbent assay (ELISA). Gene and protein expressions of StAR, P450scc and CYP19 were determined by Real-Time PCR and western blot techniques. It was observed that 30-60 mg/kg GEN could increase the expression of androgen generating key enzymes in the young rat ovary. GEN also significantly increased progesterone and E2 levels in the serum of aged rats and reduced the levels of LH and FSH in the serum of both young and aged rats. Compared with young rats, the effect of GEN on the ovary of aged rats was stronger and a lower dose of GEN (15 mg/kg) showed an obvious effect on these indicators. GEN influenced both estrogen level and indicators associated with estrogen and androgen transformation processes, which indicates that GEN can impair the growth and maturation of the ovary.

Pubertal and Adult Testicular Functions in Nonclassic Lipoid Congenital Adrenal Hyperplasia: A Case Series and Review

Lipoid congenital adrenal hyperplasia (LCAH) is caused by mutations in STAR and characterized by a defect in steroidogenesis and lipid droplet accumulation in steroidogenic cells. Patients with 46,XY and classic LCAH will typically present with female-type external genitalia. However, those with nonclassic LCAH will have masculinized external genitalia. The rarity of the nonclassic form has precluded the clarification of the long-term outcomes of testicular function in nonclassic LCAH. We report the cases of three adult males with nonclassic LCAH in whom primary adrenal insufficiency had been diagnosed at 5 days, 4 years, and 5 years of age. All exhibited complete male external genitalia and had completed pubertal development without androgen replacement. The endocrinological data showed preserved gonadal function in patients 1 and 2 and hypergonadotropic hypogonadism in patient 3. Semen analyses showed normozoospermia in patient 1 and mild oligozoospermia in patient 2. Electron microscopic analysis of a testicular biopsy specimen from patient 2 at 13 years of age revealed prominent lipid accumulation in the cytosol of Leydig cells. Patients 1 and 2 shared the same compound heterozygous mutations in STAR (p.Glu258* and p.Arg272Cys). Patient 3 possessed a heterozygous dominant-negative mutation in STAR (p.Gly22_Leu59del). A functional assay of a variant STAR-Arg272Cys determined the residual activity as 35% of the wild-type STAR. The results from the present case series and a review of four previously reported adult cases indicate that testosterone synthesis can be preserved in most males with nonclassic LCAH to complete pubertal development and induce germ cell maturation despite lipid accumulation in the Leydig cells.

Clinical efficacy and mechanism of growth hormone action in patients experiencing repeat implantation failure

The objectives of this study were to investigate the clinical efficacy of growth hormone (GH) in patients experiencing repeat implantation failure (RIF) and explore the possible mechanism. Forty-two RIF patients undergoing in vitro fertilization - embryo transfer (IVF-ET) were enrolled in the present trial: 22 patients who received GH (treatment group) and 20 who did not receive GH (controls). The clinical pregnancy and live birth rates in the treatment group were significantly higher than those in the control group (both P < 0.05). The treatment group expressed significantly higher levels of growth hormone receptor (GHR) mRNA than the control group (P < 0.05). Further analysis showed that GH levels in follicular fluid were positively correlated with the expression levels of mRNA encoding GHR in granulosa cells (r = 0.460, P < 0.05). GH treatment enhanced IVF pregnancy outcomes and increased the expression of GHR in granulosa cells in fluid. GH levels in follicular fluid were positively correlated with the expression levels of GHR.

A possible direct action of oxytocin on spermatogenesis and steroidogenesis in pre-pubertal mouse

The aim of this study was to evaluate the effects of in vivo and in vitro treatments of oxytocin (OT) on the testis of pre-pubertal mice. The OT treatment produced significant changes in the spermatogenic and steroidogenic activity by increasing expression of OT-receptor in the testis of pre-pubertal mice. Treatment with OT showed increased proliferation of germ cells as indicated by increased number of spermatocytes and round spermatids. Dose-dependent increase in expression of PCNA, Bcl-2 and AR proteins was observed in the testis of OT-treated mice as compared with the control and further supports the role of OT in germ cell proliferation and survival. The pre-pubertal mice treated with increasing dose of OT showed significant increase in testosterone synthesis due to dose-dependent stimulatory effects on 3β-HSD activity and increased expression of STAR, LH-receptor (LH-R) and gonadotrophin-releasing hormone receptor (GnRH-R) proteins in the testis. The in vitro study has confirmed in vivo finding showing direct action of OT on testicular steroidogenesis. Thus, OT stimulates testicular spermatogenesis and steroidogenesis by directly acting on testis in mice.

Platelet-derived growth factor BB stimulates differentiation of rat immature Leydig cells

Platelet-derived growth factor (PDGF) is one family of growth factors that regulate cell growth and differentiation. Rat Leydig cells express PDGF-β receptor (PDGFRB) during pubertal development. However, the mechanism of PDGF in the regulation of Leydig cell development is unclear. In the present study, rat immature Leydig cells were isolated from the testes of 35-day-old Sprague-Dawley rats and treated with 1 and 10 ng/mL of PDGF-BB. After 24 h of treatment, these cells were harvested for genomics profiling and the medium steroids were measured. 1 and 10 ng/mL PDGF-BB significantly increased androgen production by rat immature Leydig cells. Genomics profiling analysis showed that the expression levels of steroidogenic acute regulatory protein (Star) were increased by 2-fold. Further analysis showed that Fos expression level was increased 2- and 5-fold by 1 and 10 ng/mL PDGF-BB, respectively. In conclusion, PDGF-BB stimulated the differentiation of rat immature Leydig cells via regulating Star.

Monitoring of Dual CRISPR/Cas9-Mediated Steroidogenic Acute Regulatory Protein Gene Deletion and Cholesterol Accumulation Using High-Resolution Fluorescence In Situ Hybridization in a Single Cell

Recent advances in fluorescence microscopy, coupled with CRISPR/Cas9 gene editing technology, provide opportunities for understanding gene regulation at the single-cell level. The application of direct imaging shown here provides an in situ side-by-side comparison of CRISPR/Cas9-edited cells and adjacent unedited cells. We apply this methodology to the steroidogenic acute regulatory protein (StAR) gene in Y-1 adrenal cells and MA-10 testis cells. StAR is a gatekeeper protein that controls the access of cholesterol from the cytoplasm to the inner mitochondria. The loss of this mitochondrial cholesterol transfer mediator rapidly increases lipid droplets in cells, as seen in StAR^-/- mice. Here, we describe a dual CRISPR/Cas9 strategy marked by GFP/mCherry expression that deletes StAR activity within 12 h. We used single-molecule fluorescence in situ hybridization (sm-FISH) imaging to directly monitor the time course of gene editing in single cells. We achieved StAR gene deletion at high efficiency dual gRNA targeting to the proximal promoter and exon 2. Seventy percent of transfected cells showed a slow DNA deletion as measured by PCR, and loss of Br-cAMP stimulated transcription. This DNA deletion was seen by sm-FISH in both loci of individual cells relative to non-target Cyp11a1 and StAR exon 7. sm-FISH also distinguishes two effects on stimulated StAR expression without this deletion. Br-cAMP stimulation of primary and spliced StAR RNA at the gene loci were removed within 4 h in this dual CRISPR/Cas9 strategy before any effect on cytoplasmic mRNA and protein occurred. StAR mRNA disappeared between 12 and 24 h in parallel with this deletion, while cholesterol ester droplets increased fourfold. These alternative changes match distinct StAR expression processes. This dual gRNA and sm-FISH approach to CRISPR/Cas9 editing facilitates rapid testing of editing strategies and immediate assessment of single-cell adaptation responses without the perturbation of clonal expansion procedures.

Analysis of genes that influence sheep follicular development by different nutrition levels during the luteal phase using expression profiling

Nutrition is an important factor that regulates reproductive performance of sheep and affects follicle development. However, the correlation between nutrition and follicle development is poorly understood at the molecular level. To study its possible molecular mechanisms, we performed expression profiling of granulosa cells isolated from sheep that were fed different levels of nutrition levels during the luteal phase. To do this, ewes received a maintenance diet (M), and their estrus was synchronized by intravaginal progestogen sponges for 12 days. Ewes were randomly divided into the short-term dietary-restricted group (R; 0.5 × M) and the nutrient-supplemented group (S; 1.5 × M). RNA samples were extracted from granulosa cells. Transcriptome libraries from each group were constructed by Illumina sequencing. Among 18 468 detected genes, 170 genes were significantly differentially expressed, of which 140 genes were upregulated and 30 genes were downregulated in group S relative to group R. These genes could be candidates regulating follicular development in sheep. Gene Ontology, KEGG and clustering analyses were performed. Genes related to oocyte meiosis, such as ADCY7, were upregulated. We identified two important groups of related genes that were upregulated with improved nutrition: one group comprising the genes PTGS2, UCP2 and steroidogenic acute regulatory protein and the other group comprising interleukin-1A and interleukin-1B. The genes within each group showed similar expression patterns. Additionally, all five genes are involved in the reproduction process. Quantitative real-time PCR was performed to validate the results of expression profiling. These data in our study are an abundant genomic resource to expand the understanding of the molecular and cellular events underlying follicle development.

Adrenal Mitochondria and Steroidogenesis: From Individual Proteins to Functional Protein Assemblies

The adrenal cortex is critical for physiological function as the central site of glucocorticoid and mineralocorticoid synthesis. It possesses a great degree of specialized compartmentalization at multiple hierarchical levels, ranging from the tissue down to the molecular levels. In this paper, we discuss this functionalization, beginning with the tissue zonation of the adrenal cortex and how this impacts steroidogenic output. We then discuss the cellular biology of steroidogenesis, placing special emphasis on the mitochondria. Mitochondria are classically known as the "powerhouses of the cell" for their central role in respiratory adenosine triphosphate synthesis, and attention is given to mitochondrial electron transport, in both the context of mitochondrial respiration and mitochondrial steroid metabolism. Building on work demonstrating functional assembly of large protein complexes in respiration, we further review research demonstrating a role for multimeric protein complexes in mitochondrial cholesterol transport, steroidogenesis, and mitochondria-endoplasmic reticulum contact. We aim to highlight with this review the shift in steroidogenic cell biology from a focus on the actions of individual proteins in isolation to the actions of protein assemblies working together to execute cellular functions.

The nuclear receptor NR2F2 activates star expression and steroidogenesis in mouse MA-10 and MLTC-1 Leydig cells

Testosterone production is dependent on cholesterol transport within the mitochondrial matrix, an essential step mediated by a protein complex containing the steroidogenic acute regulatory (STAR) protein. In steroidogenic Leydig cells, Star expression is hormonally regulated and involves several transcription factors. NR2F2 (COUP-TFII) is an orphan nuclear receptor that plays critical roles in cell differentiation and lineage determination. Conditional NR2F2 knockout prior to puberty leads to male infertility due to insufficient testosterone production, suggesting that NR2F2 could positively regulate steroidogenesis and Star expression. In this study we found that NR2F2 is expressed in the nucleus of some peritubular myoid cells and in interstitial cells, mainly in steroidogenically active adult Leydig cells. In MA-10 and MLTC-1 Leydig cells, small interfering RNA (siRNA)-mediated NR2F2 knockdown reduces basal steroid production without affecting hormone responsiveness. Consistent with this, we found that STAR mRNA and protein levels were reduced in NR2F2-depleted MA-10 and MLTC-1 cells. Transient transfections of Leydig cells revealed that a -986 bp mouse Star promoter construct was activated 3-fold by NR2F2. Using 5' progressive deletion constructs, we mapped the NR2F2-responsive element between -131 and -95 bp. This proximal promoter region contains a previously uncharacterized direct repeat 1 (DR1)-like element to which NR2F2 is recruited and directly binds. Mutations in the DR1-like element that prevent NR2F2 binding severely blunted NR2F2-mediated Star promoter activation. These data identify an essential role for the nuclear receptor NR2F2 as a direct activator of Star gene expression in Leydig cells, and thus in the control of steroid hormone biosynthesis.

Wnt/β-catenin signaling regulates follicular development by modulating the expression of Foxo3a signaling components

Wnt signaling is an evolutionarily conserved pathway that regulates cell proliferation, differentiation and apoptosis. To investigate the possible role of Wnt signaling in the regulation of ovarian follicular development, secondary follicles were isolated and cultured in vitro in the presence or absence of its activator (LiCl or Wnt3a) or inhibitor (IWR-1). We have demonstrated that activation of β-catenin signals by activators dramatically suppressed follicular development by increasing granulosa cell apoptosis and inhibiting follicle steroidogenesis. In contrast, inhibition of Wnt signaling by IWR-1 was observed with better developed follicles and increased steroidogenesis. Further studies have shown that the transcription factor Forkhead box O3a (Foxo3a) and its downstream target molecules were modulated by the activators or the inhibitor. These findings provide evidence that Wnt signaling might negatively regulate follicular development potentially through Foxo3a signaling components.

Social stress modulates the cortisol response to an acute stressor in rainbow trout (Oncorhynchus mykiss)

In rainbow trout (Oncorhynchus mykiss) of subordinate social status, circulating cortisol concentrations were elevated under resting conditions but the plasma cortisol and glucose responses to an acute stressor (confinement in a net) were attenuated relative to those of dominant trout. An in vitro head kidney preparation, and analysis of the expression of key genes in the stress axis prior to and following confinement in a net were then used to examine the mechanisms underlying suppression of the acute cortisol stress response in trout experiencing chronic social stress. With porcine adrenocorticotropic hormone (ACTH) as the secretagogue, ACTH-stimulated cortisol production was significantly lower for head kidney preparations from subordinate trout than for those from dominant trout. Dominant and subordinate fish did not, however, differ in the relative mRNA abundance of melanocortin-2 receptor (MC2R), steroidogenic acute regulatory protein (StAR) or cytochrome P450 side chain cleavage enzyme (P450scc) within the head kidney, although the relative mRNA abundance of these genes was significantly higher in both dominant and subordinate fish than in sham trout (trout that did not experience social interactions but were otherwise treated identically to the dominant and subordinate fish). The relative mRNA abundance of all three genes was significantly higher in trout exposed to an acute net stressor than under control conditions. Upstream of cortisol production in the stress axis, plasma ACTH concentrations were not affected by social stress, nor was the relative mRNA abundance of the binding protein for corticotropin releasing factor (CRF-BP). The relative mRNA abundance of CRF in the pre-optic area of subordinate fish was significantly higher than that of dominant or sham fish 1h after exposure to the stressor. Collectively, the results indicate that chronic social stress modulates cortisol production at the level of the interrenal cells, resulting in an attenuated cortisol response to an acute stressor.

Exposure to DEHP and MEHP from hatching to adulthood causes reproductive dysfunction and endocrine disruption in marine medaka (Oryzias melastigma)

Concern has increased regarding the adverse effects of di-(2-ethylhexyl)-phthalate (DEHP) on reproduction. However, limited information is available on the effects of DEHP in marine organisms. The aim of the present study was to examine whether long-term exposure to DEHP and its active metabolite mono-(2-ethylhexyl)-phthalate (MEHP) disrupts endocrine function in marine medaka (Oryzias melastigma). Marine medaka larvae were exposed to either DEHP (0.1 and 0.5mg/L) or MEHP (0.1 and 0.5mg/L) for 6 months, and the effects on reproduction, sex steroid hormones, liver vitellogenin (VTG), gonad histology and the expression of genes involved in the hypothalamic-pituitary-gonad (HPG) axis were investigated. Exposure to DEHP, but not MEHP, from hatching to adulthood accelerated the start of spawning and decreased the egg production of exposed females. Moreover, exposure to both DEHP and MEHP resulted in a reduction in the fertilization rate of oocytes spawned by untreated females paired with treated males. A significant increase in plasma 17β-estradiol (E2) along with a significant decrease in testosterone (T)/E2 ratios was observed in males, which was accompanied by the upregulation of ldlr, star, cyp17a1, 17βhsd, and cyp19a transcription in the testis. Increased concentrations of T and E2 were observed in females, which was consistent with the upregulation of ldlr. The expression of brain gnrhr2, fshβ, cyp19b and steroid hormone receptor genes also corresponded well with hormonal and reproductive changes. The liver VTG level was significantly increased after DEHP and MEHP exposure in males. DEHP induced histological changes in the testes and ovaries: the testes displayed a reduced number of spermatozoa, and the ovaries displayed an increased number of atretic follicles. In addition, the tissue concentrations of MEHP, MEHHP and MEOHP in DEHP-exposed groups were much higher than those in MEHP-exposed groups, and there were no dose- or sex-specific effects. Thus, DEHP exerts more obvious toxic effects compared with MEHP. There were some commonalities in the toxic effects and molecular mechanisms of DEHP and MEHP, suggesting that some of the toxic effects of DEHP may be induced by both DEHP itself and DEHP metabolites (including MEHP). Taken together, these results indicate that exposure to DEHP and MEHP from hatching to adulthood causes endocrine disruption with sex-specific effects in marine medaka, with males being more sensitive than females.

Transcriptional regulation of human ferredoxin reductase through an intronic enhancer in steroidogenic cells

Ferredoxin reductase (FDXR, also known as adrenodoxin reductase) is a mitochondrial flavoprotein that transfers electrons from NADPH to mitochondrial cytochrome P450 enzymes, mediating the function of an iron-sulfur cluster protein, ferredoxin. FDXR functions in various metabolic processes including steroidogenesis. It is well known that multiple steroidogenic enzymes are regulated by a transcription factor steroidogenic factor-1 (SF-1, also known as Ad4BP). Previously, we have shown that SF-1 transduction causes human mesenchymal stem cell differentiation into steroidogenic cells. Genome-wide analysis of differentiated cells, using a combination of DNA microarray and promoter tiling array analyses, showed that FDXR is a novel SF-1 target gene. In this study, the transcriptional regulatory mechanism of FDXR was examined in steroidogenic cells. A chromatin immunoprecipitation assay revealed that a novel SF-1 binding region was located within intron 2 of the human FDXR gene. Luciferase reporter assays showed that FDXR transcription was activated through the novel SF-1 binding site within intron 2. Endogenous SF-1 knockdown in human adrenocortical H295R and KGN cells decreased FDXR expression. In H295R cells, strong binding of two histone markers of active enhancers, histones H3K27ac and H3K4me2, were detected near the SF-1 binding site within intron 2. Furthermore, the binding of these histone markers was decreased concurrent with SF-1 knockdown in H295R cells. These results indicated that abundant FDXR expression in these steroidogenic cells was maintained through SF-1 binding to the intronic enhancer of the FDXR gene.

Extra-adrenal glucocorticoid synthesis: immune regulation and aspects on local organ homeostasis

Systemic glucocorticoids (GCs) mainly originate from de novo synthesis in the adrenal cortex under the control of the hypothalamus-pituitary-adrenal (HPA)-axis. However, research during the last 1-2 decades has revealed that additional organs express the necessary enzymes and have the capacity for de novo synthesis of biologically active GCs. This includes the thymus, intestine, skin and the brain. Recent research has also revealed that locally synthesized GCs most likely act in a paracrine or autocrine manner and have significant physiological roles in local homeostasis, cell development and immune cell activation. In this review, we summarize the nature, regulation and known physiological roles of extra-adrenal GC synthesis. We specifically focus on the thymus in which GC production (by both developing thymocytes and epithelial cells) has a role in the maintenance of proper immunological function.

CCAAT/enhancer-binding protein β is involved in the breed-dependent transcriptional regulation of 3β-hydroxysteroid dehydrogenase/Δ(5)-Δ(4)-isomerase in adrenal gland of preweaning piglets

The enzyme 3β-hydroxysteroid dehydrogenase/Δ(5)-Δ(4)-isomerase (3β-HSD) catalyzes the biosynthesis of all steroid hormones. The molecular mechanisms regulating porcine adrenal 3β-HSD expression in different breeds are still poorly understood. In this study, we aimed to compare the expression of 3β-HSD between preweaning purebred Large White (LW) and Erhualian (EHL) piglets and to explore the potential factors regulating 3β-HSD transcription. EHL had significantly higher serum levels of cortisol (P<0.01) and testosterone (P<0.01), which were associated with significantly higher expression of 3β-HSD mRNA (P<0.01) and protein (P<0.05) in the adrenal gland, compared with LW piglets. The 5' flanking region of the porcine 3β-HSD gene showed significant sequence variations between breeds, and the sequence of EHL demonstrated an elevated promoter activity (P<0.05) in luciferase reporter gene assay. Higher adrenal expression of 3β-HSD in EHL was accompanied with higher CCAAT/enhancer binding protein β (C/EBPβ) expression (P<0.05), enriched histone H3 acetylation (P<0.05) and C/EBPβ binding to 3β-HSD promoter (P<0.05). In addition, higher androgen receptor (AR) (P=0.06) and lower glucocorticoid receptor (GR) (P<0.05) were detected in EHL. Co-immunoprecipitation analysis revealed interactions of C/EBPβ with both AR and GR. These results indicate that the C/EBPβ binding to 3β-HSD promoter is responsible, at least in part, for the breed-dependent 3β-HSD expression in adrenal gland of piglets. The sequence variations of 3β-HSD promoter and the interactions of AR and/or GR with C/EBPβ may also participate in the regulation.

Glucocorticoid metabolism in the developing lung: adrenal-like synthesis pathway

Glucocorticoids (GCs) are essential to normal lung development. They participate in the regulation of important developmental events including morphological changes, and lung maturation leading to the surge of surfactant synthesis by type II epithelial cells. Antenatal GC is administered to mothers at risk of premature delivery to reduce the risk of respiratory distress syndrome (RDS). Sex differences were reported in RDS, in the efficiency of antenatal GC treatment independently of surfactant levels, and in surfactant lipid synthesis. Type II epithelial cell maturation is regulated by epithelial-fibroblast cell-cell communication and involves paracrine factors secreted by fibroblasts under the stimulatory effect of GC. This positive action of GC can be inhibited by androgens through the androgen receptor (AR) present in fibroblasts. In fact, lung development is regulated not only by GC and androgens but also by GC and androgen metabolisms within the developing lung. We recently reviewed the metabolism of androgens in the fetal lung [45]. Here, we review multiple aspects of GC metabolism in the developing lung including inactivation and re-activation by 11β-HSDs, synthesis from the adrenal-like synthesis pathway expressed within the lung and the putative role of CRH and ACTH originating from lung in the regulation of this pathway. This article is part of a Special Issue entitled 'Pregnancy and Steroids'.

Steroidogenic acute regulatory protein transcript abundance in the eel, Anguilla australis: changes during the induced reproductive cycle and effects of follicle-stimulating hormone during previtellogenesis

Steroidogenic acute regulatory protein (StAR) mRNA levels in the eel ovary were assayed by quantitative PCR and related to plasma steroid levels throughout oogenesis in order to shed light on the previously considered 'aberrant' prematurational increase in plasma levels of estradiol-17β (E2). Total ovarian StAR transcript abundance mirrored circulating levels of E2, but not of 11-ketotestosterone (11KT). The study was complemented by evaluation of in vitro effects of follicle-stimulating hormone (FSH) on ovarian StAR transcript abundance and on short-term ('acute') radiolabelled pregnenolone-supported steroid metabolism by ovarian fragments to understand how the production of steroids during previtellogenic oocyte growth is regulated. We observed a significant effect of FSH on StAR mRNA levels within 24h of incubation, but these were no longer evident by 4 days of culture. Unexpectedly, FSH had no effect on substrate-supported steroidogenesis, as comparable yields of steroid products were detected using semi-quantitative HPLC and scintillation counting. We conclude that the eel ovarian follicle can respond to FSH from a very early stage of development (early oil droplet stage) by increasing StAR mRNA levels, but that there is no evidence for acute effects of FSH on bioactive steroid production downstream of cytochrome P450 side-chain cleavage. Furthermore, the prematurational increase in StAR mRNA in vivo is in keeping with general teleost models and is likely to be a 'normal' response to reaching advanced stages of development.

Effects of granulosa cells on steroidogenesis, proliferation and apoptosis of stromal cells and theca cells derived from the goat ovary

The aim of this study was to investigate the effect of granulosa cells from small antral follicles on steroidogenesis, proliferation and apoptosis of goat ovarian stromal and theca cells in vitro. Using Transwell co-culture system, we evaluated androgen production, LH responsiveness, cell proliferation and apoptosis and some molecular expression regarding steroidogenic enzyme and apoptosis-related genes in stromal and theca cells. The results indicated that the co-culture with granulosa cells increased steroidogenesis, LH responsiveness and bcl-2 gene expression as well as decreased apoptotic bax and bad expressions in stromal and theca cells. Thus, granulosa cells had a capacity of promoting steroidogenesis in stromal cell and LH responsiveness in cortical stromal cells, maintaining steroidogenesis in theca cells, inhibiting apoptosis of cortical stromal cells and improving anti-apoptotic abilities of stromal and theca cells.

Steroid hormone synthesis in mitochondria

Mitochondria are essential sites for steroid hormone biosynthesis. Mitochondria in the steroidogenic cells of the adrenal, gonad, placenta and brain contain the cholesterol side-chain cleavage enzyme, P450scc, and its two electron-transfer partners, ferredoxin reductase and ferredoxin. This enzyme system converts cholesterol to pregnenolone and determines net steroidogenic capacity, so that it serves as the chronic regulator of steroidogenesis. Several other steroidogenic enzymes, including 3β-hydroxysteroid dehydrogenase, 11β-hydroxylase and aldosterone synthase also reside in mitochondria. Similarly, the mitochondria of renal tubular cells contain two key enzymes participating in the activation and degradation of vitamin D. The access of cholesterol to the mitochondria is regulated by the steroidogenic acute regulatory protein, StAR, serving as the acute regulator of steroidogenesis. StAR action requires a complex multi-component molecular machine on the outer mitochondrial membrane (OMM). Components of this machine include the 18 kDa translocator protein (TSPO), the voltage-dependent anion chanel (VDAC-1), TSPO-associated protein 7 (PAP7, ACBD3), and protein kinase A regulatory subunit 1α (PKAR1A). The precise fashion in which these proteins interact and move cholesterol from the OMM to P450scc, and the means by which cholesterol is loaded into the OMM, remain unclear. Human deficiency diseases have been described for StAR and for all the mitochondrial steroidogenic enzymes, but not for the electron transfer proteins or for the components of the cholesterol import machine.

Transcriptomic profiling of progesterone in the male fathead minnow (Pimephales promelas) testis

P4 is a hormone with diverse functions that include roles in reproduction, growth, and development. The objectives of this study were to examine the effects of P4 on androgen production in the mature teleost testis and to identify molecular signaling cascades regulated by P4 to improve understanding of its role in male reproduction. Fathead minnow (FHM) testis explants were treated in vitro with two concentrations of P4 (10(-8) and 10(-6) M) for 6 and 12 h. P4 significantly increased testosterone (T) production in the FHM testis but did not affect 11-ketotestosterone. Gene network analysis revealed that insulin growth factor (Igf1) and tumor necrosis factor receptor (Tnfr) signaling was significantly depressed with P4 treatment after 12h. There was also a 20% increase in a gene network for follicle-stimulating hormone secretion and an 18% decrease in genes involved in vasopressin signaling. Genes in steroid metabolism (e.g. star, cyp19a, 11bhsd) were not significantly affected by P4 treatments in this study, and it is hypothesized that pre-existing molecular machinery may be more involved in the increased production of T rather than the de novo expression of steroid-related transcripts and receptors. There was a significant decrease in prostaglandin E synthase 3b (cytosolic) (ptges3b) after treatment with P4, suggesting that there is cross talk between P4 and prostaglandin pathways in the reproductive testis. P4 has a role in regulating steroid production in the male testis and may do so by modulating gene networks related to endocrine pathways, such as Igf1, Tnfr, and vasopressin.

The eosinophil chemoattractant 5-oxo-ETE and the OXE receptor

5-Oxo-ETE (5-oxo-6,8,11,14-eicosatetraenoic acid) is formed from the 5-lipoxygenase product 5-HETE (5S-hydroxy-6,8,11,14-eicosatetraenoic acid) by 5-hydroxyeicosanoid dehydrogenase (5-HEDH). The cofactor NADP(+) is a limiting factor in the synthesis of 5-oxo-ETE because of its low concentrations in unperturbed cells. Activation of the respiratory burst in phagocytic cells, oxidative stress, and cell death all dramatically elevate both intracellular NADP(+) levels and 5-oxo-ETE synthesis. 5-HEDH is widely expressed in inflammatory, structural, and tumor cells. Cells devoid of 5-lipoxygenase can synthesize 5-oxo-ETE by transcellular biosynthesis using inflammatory cell-derived 5-HETE. 5-Oxo-ETE is a chemoattractant for neutrophils, monocytes, and basophils and promotes the proliferation of tumor cells. However, its primary target appears to be the eosinophil, for which it is a highly potent chemoattractant. The actions of 5-oxo-ETE are mediated by the highly selective OXE receptor, which signals by activating various second messenger pathways through the release of the βγ-dimer from Gi/o proteins to which it is coupled. Because of its potent effects on eosinophils, 5-oxo-ETE may be an important mediator in asthma, and, because of its proliferative effects, may also contribute to tumor progression. Selective OXE receptor antagonists, which are currently under development, could be useful therapeutic agents in asthma and other allergic diseases.

Steroidogenesis in the skin: implications for local immune functions

The skin has developed a hierarchy of systems that encompasses the skin immune and local steroidogenic activities in order to protect the body against the external environment and biological factors and to maintain local homeostasis. Most recently it has been established that skin cells contain the entire biochemical apparatus necessary for production of glucocorticoids, androgens and estrogens either from precursors of systemic origin or, alternatively, through the conversion of cholesterol to pregnenolone and its subsequent transformation to biologically active steroids. Examples of these products are corticosterone, cortisol, testosterone, dihydrotesterone and estradiol. Their local production can be regulated by locally produced corticotropin releasing hormone (CRH), adrenocorticotropic hormone (ACTH) or cytokines. Furthermore the production of glucocorticoids is affected by ultraviolet B radiation. The level of production and nature of the final steroid products are dependent on the cell type or cutaneous compartment, e.g., epidermis, dermis, adnexal structures or adipose tissue. Locally produced glucocorticoids, androgens and estrogens affect functions of the epidermis and adnexal structures as well as local immune activity. Malfunction of these steroidogenic activities can lead to inflammatory disorders or autoimmune diseases. The cutaneous steroidogenic system can also have systemic effects, which are emphasized by significant skin contribution to circulating androgens and/or estrogens. Furthermore, local activity of CYP11A1 can produce novel 7Δ-steroids and secosteroids that are biologically active. Therefore, modulation of local steroidogenic activity may serve as a new therapeutic approach for treatment of inflammatory disorders, autoimmune processes or other skin disorders. In conclusion, the skin can be defined as an independent steroidogenic organ, whose activity can affect its functions and the development of local or systemic inflammatory or autoimmune diseases. This article is part of a Special Issue entitled 'CSR 2013'.

Fetal origin of endocrine dysfunction in the adult: the phthalate model

Di-(2-ethylhexyl) phthalate (DEHP) is a plasticizer with endocrine disrupting properties that is found ubiquitously in the environment as well as in human amniotic fluid, umbilical cord blood, human milk, semen, and saliva. It is used in the industry to add flexibility to polyvinyl chloride-derived plastics and its wide spread use and presence has resulted in constant human exposure through fetal development and postnatal life. Epidemiological studies have suggested an association between phthalate exposures and human reproductive effects in infant and adult populations. The effects of fetal exposure to phthalates on the male reproductive system were unequivocally shown on animal models, principally rodents, in which short term deleterious reproductive effects are well established. By contrast, information on the long term effects of DEHP in utero exposure on gonadal function are scarce, while its potential effects on other organs are just starting to emerge. The present review focuses on these novel findings, which suggest that DEHP exerts more complex and broader disruptive effects on the endocrine system and metabolism than previously thought. This article is part of a Special Issue entitled "CSR 2013".

Oxidative stress and phthalate-induced down-regulation of steroidogenesis in MA-10 Leydig cells

Previous studies have shown that phthalate exposure can suppress steroidogenesis. However, the affected components of the steroidogenic pathway, and the mechanisms involved, remain uncertain. We show that incubating MA-10 Leydig cells with mono-(2-ethylhexyl) phthalate (MEHP) resulted in reductions in luteinizing hormone (LH)-stimulated cAMP and progesterone productions. cAMP did not decrease in response to MEHP when the cells were incubated with cholera toxin or forskolin. Incubation of MEHP-treated cells with dibutyryl-cAMP, 22-hydroxycholesterol or pregnenolone inhibited the reductions in progesterone. Increased levels of reactive oxygen species (ROS) occurred in response to MEHP. In cells in which intracellular glutathione was depleted by buthionine sulfoximine pretreatment, the increases in ROS and decreases in progesterone in response to MEHP treatment were exacerbated. These results indicate that MEHP inhibits MA-10 Leydig cell steroidogenesis by targeting LH-stimulated cAMP production and cholesterol transport, and that a likely mechanism by which MEHP acts is through increased oxidative stress.

Low-dose monobutyl phthalate stimulates steroidogenesis through steroidogenic acute regulatory protein regulated by SF-1, GATA-4 and C/EBP-beta in mouse Leydig tumor cells

BACKGROUND

The ubiquitous use of dibutyl phthalate (DBP), one of the most widely used plasticizers, results in extensive exposure to humans and the environment. DBP and its major metabolite, monobutyl phthalate (MBP), may alter steroid biosynthesis and their exposure may lead to damage to male reproductive function. Low-doses of DBP/MBP may result in increased steroidogenesis in vitro and in vivo. However, the mechanisms of possible effects of low-dose MBP on steroidogenesis remain unclear. The aim of present study was to elaborate the role of transcription factors and steroidogenic acute regulatory protein in low-dose MBP-induced distruption of steroidogenesis in mouse Leydig tumor cells (MLTC-1 cells).

METHODS

In the present study, MLTC-1 cells were cultured in RPMI 1640 medium supplemented with 2 g/L sodium bicarbonate. Progesterone level was examined by I125-pregesterone Coat-A-Count radioimmunoassay (RIA) kits. mRNA and protein levels were assessed by reverse transcription-polymerase chain reaction (RT-PCR) and western blot, respectively. DNA-binding of several transcription factors was examined by electrophoretic mobility shift assay (EMSA).

RESULTS

In this study, various doses of MBP (0, 10(-9), 10(-8), 10(-7), or 10(-6) M) were added to the medium followed by stimulation of MLTC-1 cells with human chorionic gonadotrophin (hCG). The results showed that MBP increased progesterone production and steroidogenic acute regulatory protein (StAR) mRNA and protein levels. However, the protein levels of cytochrome P450scc and 3 beta-hydroxy-steroid dehydrogenase (3 beta-HSD) were unchanged after MBP treatment. EMSA assay showed that DNA-binding of steroidogenic factors 1(SF-1), GATA-4 and CCAAT/enhancer binding protein-beta (C/EBP-beta) was increased in a dose-dependent manner after MBP exposure. Western blot tests were next employed and confirmed that the protein levels of SF-1, GATA-4 and C/EBP-beta were also increased. Additionally, western blot tests confirmed the expression of DAX-1, negative factor of SF-1, was dose-dependently down regulated after MBP exposure, which further confirmed the role of SF-1 in MBP-stimulated steroid biosynthesis.

CONCLUSIONS

In conclusion, we firstly delineated the regulation of StAR by transcription factors including SF-1, GATA-4 and C/EBP-beta maybe critical mechanism involved in low-dose MBP-stimulated steroidogenesis.

MicroRNA-133b stimulates ovarian estradiol synthesis by targeting Foxl2

Forkhead L2 (Foxl2) is expressed in ovarian granulosa cells and participates in steroidogenesis by transcriptionally regulating target genes such as steroidogenic acute regulatory protein (StAR) and CYP19A1. In this study, a direct link between microRNA-133b (miR-133b) and Foxl2-mediated estradiol release in granulosa cells was established. miR-133b was involved in follicle-stimulating hormone (FSH)-induced estrogen production. Luciferase assays confirmed that miR-133b was bound to the 3' untranslated region (3'UTR) of Foxl2 mRNA. Consistent with this finding, miR-133b overexpression reduced the Foxl2 levels. Furthermore, miR-133b inhibited Foxl2 binding to the StAR and CYP19A1 promoter sequences. These results demonstrate that miR-133b down-regulates Foxl2 expression in granulosa cells by directly targeting the 3'UTR, thus inhibiting the Foxl2-mediated transcriptional repression of StAR and CYP19A1to promote estradiol production.

Antenatal glucocorticoid exposure enhances the inhibition of adrenal steroidogenesis by leptin in a sex-specific fashion

Antenatal treatment with glucocorticoids (GC) poses long-lasting effects on endocrine and cardiovascular function. Given that leptin attenuates adrenal function and the reported sex differences in plasma leptin concentration, we hypothesized that antenatal GC will affect leptin levels and leptin modulation of adrenal function in a sex-specific manner. Pregnant sheep were randomly given betamethasone or vehicle at 80 days of gestational age, and offspring were allowed to deliver at term. Adrenocortical cells (ADC) were studied from male and female animals at 1.5 yr of age. Plasma leptin was increased 66% in male and 41% in female GC-treated animals (P < 0.05), but adrenal leptin mRNA was increased only in GC-treated males (P < 0.05). Whereas mRNA expression of adrenal leptin receptor isoforms showed sex (Ob-Ra and Ob-Rb) and treatment-dependent (Ob-Rb) differences, protein expression remained unchanged. GC-treated females showed greater plasma cortisol and greater ACTH-stimulated cortisol production (P < 0.05) in ADC. Leptin exerted a greater inhibitory effect on basal and stimulated cortisol by ADC from GC-treated males (P < 0.05), with no differences in females. Similarly, greater inhibitory effects on basal and ACTH-stimulated StAR and ACTH-R mRNA expression by leptin were observed in cells from GC males (P < 0.05), with no changes in females. Persistent effects of antenatal GC on leptin levels and leptin modulation of adrenal function are expressed in a sex-specific manner; males are more sensitive than females to the inhibitory influences of leptin on adrenal function, and this effect appears to be mediated by a greater inhibition of StAR and ACTH-R expression in adrenals of adult GC-treated males.

Bisphenol A exposure during adulthood causes augmentation of follicular atresia and luteal regression by decreasing 17β-estradiol synthesis via downregulation of aromatase in rat ovary

BACKGROUND

Bisphenol A (BPA) has been detected in human body fluids, such as serum and ovarian follicular fluids. Several reports indicated that BPA exposure is associated with the occurrence of several female reproductive diseases resulting from the disruption of steroid hormone biosynthesis in the adult ovary.

OBJECTIVE

We hypothesized that long-term exposure to low concentrations of BPA disrupts 17β-estradiol (E2) production in granulosa cells via an alteration of steroidogenic proteins in ovarian cells.

METHODS

Adult female rats received BPA for 90 days by daily gavage at doses of 0, 0.001, or 0.1 mg/kg body weight. We determined serum levels of E2, testosterone (T), follicle-stimulating hormone (FSH), and luteinizing hormone (LH). We also analyzed the expressions of steroidogenic acute regulatory protein (StAR), P450 side-chain cleavage (P450scc), 3β-hydroxysteroid dehydrogenase isomerase (3β-HSD), and aromatase cytochrome P450 (P450arom) in the ovary.

RESULTS

Exposure to BPA significantly decreased E2 serum concentration, which was accompanied by augmented follicular atresia and luteal regression via increase of caspase-3-associated apoptosis in ovarian cells. After BPA exposure, P450arom and StAR protein levels were significantly decreased in granulosa cells and theca-interstitial (T-I) cells, respectively. However, P450scc and 3β-HSD protein levels remained unchanged. The increase in LH levels appeared to be associated with the decreased synthesis of T in T-I cells after BPA exposure via homeostatic positive feedback regulation.

CONCLUSIONS

BPA exposure during adulthood can disturb the maintenance of normal ovarian functions by reducing E2. The steroidogenic proteins StAR and P450arom appear to be targeted by BPA.

An approach for integrating toxicogenomic data in risk assessment: the dibutyl phthalate case study

An approach for evaluating and integrating genomic data in chemical risk assessment was developed based on the lessons learned from performing a case study for the chemical dibutyl phthalate. A case study prototype approach was first developed in accordance with EPA guidance and recommendations of the scientific community. Dibutyl phthalate (DBP) was selected for the case study exercise. The scoping phase of the dibutyl phthalate case study was conducted by considering the available DBP genomic data, taken together with the entire data set, for whether they could inform various risk assessment aspects, such as toxicodynamics, toxicokinetics, and dose-response. A description of weighing the available dibutyl phthalate data set for utility in risk assessment provides an example for considering genomic data for future chemical assessments. As a result of conducting the scoping process, two questions--Do the DBP toxicogenomic data inform 1) the mechanisms or modes of action?, and 2) the interspecies differences in toxicodynamics?--were selected to focus the case study exercise. Principles of the general approach include considering the genomics data in conjunction with all other data to determine their ability to inform the various qualitative and/or quantitative aspects of risk assessment, and evaluating the relationship between the available genomic and toxicity outcome data with respect to study comparability and phenotypic anchoring. Based on experience from the DBP case study, recommendations and a general approach for integrating genomic data in chemical assessment were developed to advance the broader effort to utilize 21st century data in risk assessment.

Subcellular localization and regulation of StarD4 protein in macrophages and fibroblasts

StarD4 is a member of the StarD4 subfamily of START domain proteins with a characteristic lipid binding pocket specific for cholesterol. The objective of this study was to define StarD4 subcellular localization, regulation, and function. Immunobloting showed that StarD4 is highly expressed in the mouse fibroblast cell line 3T3-L1, in human THP-1 macrophages, Kupffer cells (liver macrophages), and hepatocytes. In 3T3-L1 cells and THP-1 macrophages, StarD4 protein appeared localized to the cytoplasm and the endoplasmic reticulum (ER). More specifically, in THP-1 macrophages StarD4 co-localized to areas of the ER enriched in Acyl-CoA:cholesterol acyltransferase-1 (ACAT-1), and was closely associated with budding lipid droplets. The addition of purified StarD4 recombinant protein to an in vitro assay increased ACAT activity 2-fold, indicating that StarD4 serves as a rate-limiting step in cholesteryl ester formation by delivering cholesterol to ACAT-1-enriched ER. In addition, StarD4 protein was found to be highly regulated and to redistribute in response to sterol levels. In summary, these observations, together with our previous findings demonstrating the ability of increased StarD4 expression to increase bile acid synthesis and cholesteryl ester formation, provide strong evidence for StarD4 as a highly regulated, non-vesicular, directional, intracellular transporter of cholesterol which plays a key role in the maintenance of intracellular cholesterol homeostasis.

Mitochondrial protein import and the genesis of steroidogenic mitochondria

The principal site of regulation of steroid hormone biosynthesis is the transfer of cholesterol from the outer to inner mitochondrial membrane. Hormonal stimulation of steroidogenic cells promotes this mitochondrial lipid import through a multi-protein complex, termed the transduceosome, spanning the two membranes. The transduceosome complex is assembled from multiple proteins, such as the steroidogenic acute regulatory (STAR) protein and translocator protein (TSPO), and requires their targeting to the mitochondria for transduceosome function. The vast majority of mitochondrial proteins, including those participating in cholesterol import, are encoded in the nucleus. Their subsequent mitochondrial incorporation is performed through a series of protein import machineries located in the outer and inner mitochondrial membranes. Here we review our current knowledge of the mitochondrial cholesterol import machinery of the transduceosome. This is complemented with descriptions of mitochondrial protein import machineries and mechanisms by which these machineries assemble the transduceosome in steroidogenic mitochondria.

Effects of varicocele on testosterone, apoptosis and expression of StAR mRNA in rat Leydig cells

The aim of this study was to explore the effects of varicocele on the morphology and function of Leydig cells in the rat testis. Forty male Sprague-Dawley rats were divided into two groups: the experimental group underwent surgery to create a left varicocele (VC), and the control group underwent a sham operation. Serum testosterone and intratesticular testosterone levels were measured using a radioimmunoassay after 4 and 8 weeks of operation. Leydig cells were studied for apoptosis and expression of steroidogenetic acute regulatory (StAR) protein mRNA levels. Serum testosterone levels declined after 4 and 8 weeks of operation but were not significant (P>0.05). However, the intratesticular testosterone levels after 8 weeks were significantly decreased compared with the control group (P<0.01). The mean apoptosis index of Leydig cells in the experimental group was significantly higher than that in the control group after 4 or 8 weeks (P<0.01). StAR mRNA levels in the Leydig cells of the experimental group were significantly lower compared to those of the control group (P<0.01). Our data show that varicocele did impair Leydig cell function by increasing apoptosis and suppressing the expression of the StAR protein.

Steroidogenic acute regulatory protein expression in the central nervous system

Locally produced neurosteroids are proposed to have many functions in the central nervous system. The identification of the steroidogenic acute regulatory protein in steroid-producing neural cells provides a new tool to understand the sites, regulation, and importance of their synthesis.

Adrenal peripheral clock controls the autonomous circadian rhythm of glucocorticoid by causing rhythmic steroid production

Glucocorticoid (GC) is an adrenal steroid with diverse physiological effects. It undergoes a robust daily oscillation, which has been thought to be driven by the master circadian clock in the suprachiasmatic nucleus of the hypothalamus via the hypothalamus-pituitary-adrenal axis. However, we show that the adrenal gland has its own clock and that the peripheral clockwork is tightly linked to steroidogenesis by the steroidogenic acute regulatory protein. Examination of mice with adrenal-specific knockdown of the canonical clock protein BMAL1 reveals that the adrenal clock machinery is required for circadian GC production. Furthermore, behavioral rhythmicity is drastically affected in these animals, together with altered expression of Period1, but not Period2, in several peripheral organs. We conclude that the adrenal peripheral clock plays an essential role in harmonizing the mammalian circadian timing system by generating a robust circadian GC rhythm.

Intracellular cholesterol transporter StarD4 binds free cholesterol and increases cholesteryl ester formation

StarD4 protein is a member of the StarD4 subfamily of steroidogenic acute regulatory-related lipid transfer (START) domain proteins that includes StarD5 and StarD6, proteins whose functions remain poorly defined. The objective of this study was to isolate and characterize StarD4's sterol binding and to determine in a hepatocyte culture model its sterol transport capabilities. Utilizing purified full-length StarD4, in vitro binding assays demonstrated a concentration-dependent binding of [(14)C]cholesterol by StarD4 similar to that of the cholesterol binding START domain proteins StarD1 and StarD5. Other tested sterols showed no detectable binding to StarD4, except for 7alpha-hydroxycholesterol, for which StarD4 demonstrated weak binding on lipid protein overlay assays. Subsequently, an isolated mouse hepatocyte model was used to study the ability of StarD4 to bind/mobilize/distribute cellular cholesterol. Increased expression of StarD4 in primary mouse hepatocytes led to a marked increase in the intracellular cholesteryl ester concentration and in the rates of bile acid synthesis. The ability and specificity of StarD4 to bind cholesterol and, as a function of its level of expression, to direct endogenous cellular cholesterol suggest that StarD4 plays an important role as a directional cholesterol transporter in the maintenance of cellular cholesterol homeostasis.