The regulation of 3 beta-hydroxysteroid dehydrogenase expression

Role of single nucleotide polymorphisms of the HSD3B1 gene (rs6203 and rs33937873) in the prediction of prostate cancer risk

3-β-hydroxysteroid dehydrogenase 1 (HSD3B1) is shown to affect dihydrotestosterone level in prostatic tissue which is a risk factor for prostate cancer (PC). The present study aimed to determine whether rs33937873 (G313A) and rs6203 (C338T) single nucleotide polymorphisms (SNP) in HSD3B1 gene was a potential risk factor for PC susceptibility and can predict the recurrence of PC in Egyptian patients. A total of 186 Egyptian patients were selected with incident primary PC and compared with 180 age healthy controls. The frequencies and the main effect of rs33937873 and rs6203 in HSD3B1 were compared and investigated between the patients and control using genotyping technique and statistical analysis. The mutant GA genotype of G313A in rs33937873 SNP was considered as an independent risk for PC in the multivariate regression analysis [odds ratio (OR)=2.7, 95% confidence intervals (CI): 1.2-5.5, P=0.01] together with positive history of hypertension (HTN) (OR=6.2, 95% CI: 3.2-12.1, P=0.0001) and begin prostatic hyperplasia (BPH; OR=8.9, 95% CI: 4.5-17.5, P=0.0001). Conversely, in rs6203 (C338T), C allele is considered as major risk allele in the development of PC (OR=1.8, 95% CI: 1.3-2.4, P=0.0003). The univariate logistic regression analyses indicated that CC genotype of rs6203 was a PC risk factor (OR=1.9, 95% CI: 1.3-2.9, P=0.002). In addition, the frequency of the A-C haplotype established by rs33937873-rs6203 was also significantly higher for PC (P=0.013). The predication of PC recurrence was associated only with positive family history (OR=7.7, 95% CI: 2.3-25.9, P=0.001) and not for The G313A and C338T SNPs. These results suggested that the two HSD3B1 polymorphisms rs33937873 and rs6203 may modify the risk of PC, particularly among patients with HTN and history of BPH, suggesting them as prominent future markers for prediction of PC risk.

Improvac induces immunocastration by affecting testosterone levels and disrupting spermatogenesis in male broiler chickens

Immunocastration (vaccination against Gonadotropin-releasing hormone (GnRH)) has been regarded as a friendly substitution to physical castration in animals. To date, a few studies have reported the use of Improvac for immunocastration in boar and one study in broiler chickens; however, there is an apparent dearth of scientific evidence regarding the application of Improvac for immunocastration in birds. In the present study, we evaluated the effects of Improvac-based immunocastration on testosterone levels and spermatogenesis in broiler chickens and the effects of Improvac on the expression of genes related to testosterone biosynthesis and metabolism as well as spermatogenesis. The birds were randomly divided into 4 groups (n = 30 each): Control group (non-immunized), Early group (immunized with Improvac at week 3), Late group (immunized with Improvac at week 6), and Early + Late group (immunized with Improvac at weeks 3 and 6). Immunization with Improvac significantly improved the average daily gain compared to the Control group. Of note, following Improvac vaccination, the reproductive efficiency was significantly decreased in male broiler chickens. Furthermore, parameters such as the serum testosterone concentration, spermatogenesis, and the expression levels of genes related to testosterone metabolism (Cyp17A1, Cyp19, HSD3B1, and HSD17B3) and spermatogenesis (Cyclin A1 and Cyclin A2) were significantly reduced in the immunized groups compared to the Control group. Taken together, these findings reveal that immunization against GnRH can be achieved, at least partially, in male broiler chickens. The results of our study also support the hypothesis of using Improvac as an alternative solution to caponization, with considerably improved animal welfare.

Energy Metabolism in Cancer: The Roles of STAT3 and STAT5 in the Regulation of Metabolism-Related Genes

A central characteristic of many types of cancer is altered energy metabolism processes such as enhanced glucose uptake and glycolysis and decreased oxidative metabolism. The regulation of energy metabolism is an elaborate process involving regulatory proteins such as HIF (pro-metastatic protein), which reduces oxidative metabolism, and some other proteins such as tumour suppressors that promote oxidative phosphorylation. In recent years, it has been demonstrated that signal transducer and activator of transcription (STAT) proteins play a pivotal role in metabolism regulation. STAT3 and STAT5 are essential regulators of cytokine- or growth factor-induced cell survival and proliferation, as well as the crosstalk between STAT signalling and oxidative metabolism. Several reports suggest that the constitutive activation of STAT proteins promotes glycolysis through the transcriptional activation of hypoxia-inducible factors and therefore, the alteration of mitochondrial activity. It seems that STAT proteins function as an integrative centre for different growth and survival signals for energy and respiratory metabolism. This review summarises the functions of STAT3 and STAT5 in the regulation of some metabolism-related genes and the importance of oxygen in the tumour microenvironment to regulate cell metabolism, particularly in the metabolic pathways that are involved in energy production in cancer cells.

Repurposing steroidogenesis inhibitors for the therapy of neuropsychiatric disorders: Promises and caveats

Steroids exert a profound influence on behavioral reactivity, by modulating the functions of most neurotransmitters and shaping the impact of stress and sex-related variables on neural processes. This background - as well as the observation that most neuroactive steroids (including sex hormones, glucocorticoids and neurosteroids) are synthetized and metabolized by overlapping enzymatic machineries - points to steroidogenic pathways as a powerful source of targets for neuropsychiatric disorders. Inhibitors of steroidogenic enzymes have been developed and approved for a broad range of genitourinary and endocrine dysfunctions, opening to new opportunities to repurpose these drugs for the treatment of mental problems. In line with this idea, preliminary clinical and preclinical results from our group have shown that inhibitors of key steroidogenic enzymes, such as 5α-reductase and 17,20 desmolase-lyase, may have therapeutic efficacy in specific behavioral disorders associated with dopaminergic hyperfunction. While the lack of specificity of these effects raises potential concerns about endocrine adverse events, these initial findings suggest that steroidogenesis modulators with greater brain specificity may hold significant potential for the development of alternative therapies for psychiatric problems. This article is part of the Special Issue entitled 'Drug Repurposing: old molecules, new ways to fast track drug discovery and development for CNS disorders'.

Genetic Variants Associated with Hyperandrogenemia in PCOS Pathophysiology

Polycystic ovary syndrome is a multifactorial endocrine disorder whose pathophysiology baffles many researchers till today. This syndrome is typically characterized by anovulatory cycles and infertility, altered gonadotropin levels, obesity, and bulky multifollicular ovaries on ultrasound. Hyperandrogenism and insulin resistance are hallmark features of its complex pathophysiology. Hyperandrogenemia is a salient feature of PCOS and a major contributor to cosmetic anomalies including hirsutism, acne, and male pattern alopecia in affected women. Increased androgen levels may be intrinsic or aggravated by preexisting insulin resistance in women with PCOS. Studies have reported augmented ovarian steroidogenesis patterns attributed mainly to theca cell hypertrophy and altered expression of key enzymes in the steroidogenic pathway. Candidate gene studies have been performed in order to delineate the association of polymorphisms in genes, which encode enzymes in the intricate cascade of steroidogenesis or modulate the levels and action of circulating androgens, with risk of PCOS development and its related traits. However, inconsistent findings have impacted the emergence of a unanimously accepted genetic marker for PCOS susceptibility. In the current review, we have summarized the influence of polymorphisms in important androgen related genes in governing genetic predisposition to PCOS and its related metabolic and reproductive traits.

Genome-Wide and Gene-Based Meta-Analyses Identify Novel Loci Influencing Blood Pressure Response to Hydrochlorothiazide

This study aimed to identify novel loci influencing the antihypertensive response to hydrochlorothiazide monotherapy. A genome-wide meta-analysis of blood pressure (BP) response to hydrochlorothiazide was performed in 1739 white hypertensives from 6 clinical trials within the International Consortium for Antihypertensive Pharmacogenomics Studies, making it the largest study to date of its kind. No signals reached genome-wide significance (P<5×10-8), and the suggestive regions (P<10-5) were cross-validated in 2 black cohorts treated with hydrochlorothiazide. In addition, a gene-based analysis was performed on candidate genes with previous evidence of involvement in diuretic response, in BP regulation, or in hypertension susceptibility. Using the genome-wide meta-analysis approach, with validation in blacks, we identified 2 suggestive regulatory regions linked to gap junction protein α1 gene (GJA1) and forkhead box A1 gene (FOXA1), relevant for cardiovascular and kidney function. With the gene-based approach, we identified hydroxy-delta-5-steroid dehydrogenase, 3 β- and steroid δ-isomerase 1 gene (HSD3B1) as significantly associated with BP response (P<2.28×10-4 ). HSD3B1 encodes the 3β-hydroxysteroid dehydrogenase enzyme and plays a crucial role in the biosynthesis of aldosterone and endogenous ouabain. By amassing all of the available pharmacogenomic studies of BP response to hydrochlorothiazide, and using 2 different analytic approaches, we identified 3 novel loci influencing BP response to hydrochlorothiazide. The gene-based analysis, never before applied to pharmacogenomics of antihypertensive drugs to our knowledge, provided a powerful strategy to identify a locus of interest, which was not identified in the genome-wide meta-analysis because of high allelic heterogeneity. These data pave the way for future investigations on new pathways and drug targets to enhance the current understanding of personalized antihypertensive treatment.

Structural modeling and in silico analysis of non-synonymous single nucleotide polymorphisms of human 3β-hydroxysteroid dehydrogenase type 2

Single-nucleotide polymorphisms (SNPs), a most common type of genetic mutations, result from single base pair alterations. Non-synonymous SNPs (nsSNP) occur in the coding regions of a gene and result in single amino acid substitution which might have the potential to affect the function as well as structure of the corresponding protein. In human the 3β-hydroxysteroid dehydrogenases/Δ^4,5-isomerase type 2 (HSD3B2) is an important membrane-bound enzyme involved in the dehydrogenation and Δ^4,5-isomerization of the Δ⁵-steroid precursors into their respective Δ⁴-ketosteroids in the biosynthesis of steroid hormones such as glucocorticoids, mineralocorticoids, progesterone, androgens, and estrogens in tissues such as adrenal gland, ovary, and testis. Most of the nsSNPs of HSD3B2 are still uncharacterized in terms of their disease causing potential. So, this study has been undertaken to explore and extend the knowledge related to the effect of nsSNPs on the stability and function of the HSD3B2. In this study sixteen nsSNP of HSD3B2 were subjected to in silico analysis using nine different algorithms: SIFT, PROVEAN, PolyPhen, MutPred, SNPeffect, nsSNP Analyzer, PhD SNP, stSNP, and I Mutant 2.0. The results obtained from the analysis revealed that the prioritization of diseases associated amino acid substitution as evident from possible alteration in structure–function relationship. Structural phylogenetic analysis using ConSurf revealed that the functional residues are highly conserved in human HSD3B2; and most of the disease associated nsSNPs are within these conserved residues. Structural theoritical models of HSD3B2 were created using HHPred, Phyre2 and RaptorX server. The predicted models were evaluated to get the best one for structural understanding of amino acid substitutions in three dimensional spaces.

Angiotensin II triggers expression of the adrenal gland zona glomerulosa-specific 3β-hydroxysteroid dehydrogenase isoenzyme through de novo protein synthesis of the orphan nuclear receptors NGFIB and NURR1

The 3β-hydroxysteroid dehydrogenase (3β-HSD) is an enzyme crucial for steroid synthesis. Two different 3β-HSD isoforms exist in humans. Classically, HSD3B2 was considered the principal isoform present in the adrenal. However, we recently showed that the alternative isoform, HSD3B1, is expressed specifically within the adrenal zona glomerulosa (ZG), where aldosterone is produced, raising the question of why this isozyme needs to be expressed in this cell type. Here we show that in both human and mouse, expression of the ZG isoform 3β-HSD is rapidly induced upon angiotensin II (AngII) stimulation. AngII is the key peptide hormone regulating the capacity of aldosterone synthesis. Using the human adrenocortical H295R cells as a model system, we show that the ZG isoform HSD3B1 differs from HSD3B2 in the ability to respond to AngII. Mechanistically, the induction of HSD3B1 involves de novo protein synthesis of the nuclear orphan receptors NGFIB and NURR1. The HSD3B1 promoter contains a functional NGFIB/NURR1-responsive element to which these proteins bind in response to AngII. Knockdown of these proteins and overexpression of a dominant negative NGFIB both reduce the AngII responsiveness of HSD3B1. Thus, the AngII-NGFIB/NURR1 pathway controls HSD3B1. Our work reveals HSD3B1 as a new regulatory target of AngII.

Environmental pollutants and hydroxysteroid dehydrogenases

Hydroxysteroid dehydrogenases (HSD) are a group of steroidogenic enzymes that are involved in the steroid biosynthesis and metabolism. Four classes of HSDs, namely, 3β-, 11β-, 17β-, and 20α-HSDs, are discussed. 3β-HSDs catalyze the conversion of pregnenolone, 17α-hydroxypregnenolone, and dehydroepiandrosterone to progesterone, 17α-hydroxyprogesterone, and androstenedione, respectively. 11β-HSDs catalyze the interconversion between active cortisol and inactive cortisone. 17β-HSDs catalyze the interconversion between 17β-hydroxyl steroids and 17-ketoandrogens and estrogens. 20α-HSDs catalyze the conversion of progesterone into 20α-hydroxyprogesterone. Many environmental pollutants directly inhibit one or more enzymes of these HSDs, thus interfering with endogenous active steroid hormone levels. These chemicals include industrial materials (perfluoroalkyl compounds, phthalates, bisphenol A, and benzophenone), pesticides/biocides (methoxychlor, organotins, 1,2-dibromo-3-chloropropane, and prochloraz), and plant constituents (genistein, gossypol, and licorice). This chapter reviews these inhibitors targeting on HSDs.

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.

Regulation of 3β-hydroxysteroid dehydrogenase/Δ⁵-Δ⁴ isomerase: a review

This review focuses on the expression and regulation of 3β-hydroxysteroid dehydrogenase/Δ⁵-Δ⁴ isomerase (3β-HSD), with emphasis on the porcine version. 3β-HSD is often associated with steroidogenesis, but its function in the metabolism of both steroids and xenobiotics is more obscure. Based on currently available literature covering humans, rodents and pigs, this review provides an overview of the present knowledge concerning the regulatory mechanisms for 3β-HSD at all omic levels. The HSD isoenzymes are essential in steroid hormone metabolism, both in the synthesis and degradation of steroids. They display tissue-specific expression and factors influencing their activity, which therefore indicates their tissue-specific responses. 3β-HSD is involved in the synthesis of a number of natural steroid hormones, including progesterone and testosterone, and the hepatic degradation of the pheromone androstenone. In general, a number of signaling and regulatory pathways have been demonstrated to influence 3β-HSD transcription and activity, e.g., JAK-STAT, LH/hCG, ERα, AR, SF-1 and PPARα. The expression and enzymic activity of 3β-HSD are also influenced by external factors, such as dietary composition. Much of the research conducted on porcine 3β-HSD is motivated by its importance for the occurrence of the boar taint phenomenon that results from high concentrations of steroids such as androstenone. This topic is also examined in this review.

Effects of nuclear receptor transactivation on boar taint metabolism and gene expression in porcine hepatocytes

The accumulation of the testicular steroid androstenone (AND) and tryptophan degradation product skatole (3MI) in fat results in boar taint, an off odor and flavor in boar meat. Increasing boar taint metabolism in the liver may help limit the deposition of AND and 3MI in fat, thereby improving meat quality. The effects of transactivation of the nuclear receptors constitutive androstane receptor (CAR), pregnane X receptor (PXR), and farnesoid X receptor (FXR) on the expression levels of several transcripts of interest and the metabolism of AND and 3MI in primary porcine hepatocytes were tested. Primary cells were isolated from mature boars, and transcript expression levels were assayed using real-time PCR. The transcripts of interest included porcine orthologs of common phase I and phase II metabolic enzymes and transcripts previously shown to be differentially expressed in boars with high boar taint levels. Transactivation of CAR, PXR, or FXR resulted in altered expression of several transcripts, including increased expression of cytochrome P450 (CYP) 2B22 by CAR, of CYP2A19, CYP2B22, CYP2C33, and CYP2C49 by PXR, of CYP2C33 and CYP2E1 by FXR, and of CYP19A2 by all three receptors. Only transactivation of PXR had a significant effect on AND metabolism, resulting in 7.5±1.5% of the initial level of AND remaining compared to 21.4±3.1% remaining with control dimethyl sulfoxide (DMSO) treatment. FXR had the greatest effect on 3MI metabolism, increasing the expression of CYP2E1 by 1.29-fold and increasing the production of the key metabolite 6-hydroxy-3-methylindole (6-OH-3MI), while decreasing 5-hydroxy-3-methylindole (5-OH-3MI) production. 3-Hydroxy-3-methyloxindole (HMOI) production was increased by CAR transactivation, while indol-3-carbinol (I3C) production was increased by PXR and FXR transactivation, and by treatment with 5β-dihydrotestosterone (5β-DHT). From this, it can be concluded that selective transactivation of PXR and FXR may be a viable means of decreasing boar taint by increasing the hepatic metabolism of AND and 3MI.

Cloning and expression of 3β-hydroxysteroid dehydrogenase during gonadal recrudescence and after hCG induction in the air-breathing catfish, Clarias gariepinus

3β-hydroxysteroid dehydrogenase (3β-hsd) plays an important role in biosynthesis of both androgens and estrogens during steroidogenesis. In this study, we report the cloning of a full-length cDNA of 3β-hsd from gonads of the air-breathing catfish, Clarias gariepinus a seasonally reproducing teleost fish. We studied the expression pattern of 3β-hsd during gonadal ontogeny and recrudescence (flanking two years of reproductive cycle) using real-time PCR. We also examined the influence of gonadotropin on 3β-hsd expression in gonads of catfish by human chorionic gonadotropin (hCG) induction. The real-time PCR results revealed that 3β-hsd transcript was detectable much earlier in undifferentiated gonads i.e. before the sex differentiation and later on its expression was seen in both male and female gonads throughout the development. The expression analysis during subsequent seasonal reproductive cycle in catfish (older than one year) showed that in adult males, the transcripts were significantly high during prespawning phase (spermatogenesis) and declined during spermiation. In adult females, the transcripts were abundantly expressed in the ovarian follicles both at prespawning and spawning phases. Furthermore, the 3β-hsd mRNA levels in different follicular stages were markedly high in vitellogenic follicles (maturing oocytes; stage III) compared to other stages. Treatment of hCG in recrudescing female fish, in vivo as well as in testicular slices, in vitro resulted in the up-regulation of gonadal 3β-hsd mRNA indicating that it is under the regulation of gonadotropins. These results together suggest that 3β-hsd gene plays an important role during spermatogenesis and oogenesis as well as in the gonadal recrudescence of catfish.

Luteinizing hormone (LH) regulates production of androstenedione and progesterone via control of histone acetylation of StAR and CYP17 promoters in ovarian theca cells

Although luteinizing hormone (LH) affects androstenedione (A4) and progesterone (P4) production in theca cells, it is still unknown how LH influences molecular mechanism of A4 and P4 production. To examine the relationship between LH and transcription factors involved in A4 and P4 production, ovarian theca cells were cultured in the presence or absence of high concentrations of LH for 24 h (pre-treatment with high concentration of LH) and then cultured in the presence or absence of low concentration of LH for 48 h. Low LH enhanced production of A4 and P4, and expressions of CYP17 and StAR mRNA in theca cells without pre-treatment with high LH. In addition, low LH stimulated the expression of SF-1 protein in nuclear fractions from theca cells with or without pre-treatment with high LH. The binding of SF-1 to the CYP17 and StAR promoter regions increased in theca cells treated with low LH. Although GATA-4 and GATA-6 are both found in the nuclear fraction but not in the cytosol of theca cells, low LH enhanced the binding of GATA-6, but not of GATA-4, to the CYP17 promoter region without pre-treatment with high LH. Acetylation histone H3 in StAR and CYP17 promoter regions were changed by different LH-dosage. Overall, we showed that LH regulates the production of A4 and P4 by affecting the nuclear localization and switching of transcription factors in theca cells and that target transcription factors involved in steroid production in theca cells are changed by different LH concentration.

Growth hormone-STAT5 regulation of growth, hepatocellular carcinoma, and liver metabolism

The liver is a primary target of growth hormone (GH). GH signals are mediated by the transcription factor signal transducer and activator of transcription 5 (STAT5). Here, we focus on recent discoveries about the role of GH-STAT5 signaling in hepatic physiology and pathophysiology. We discuss roles of the GH-STAT5 axis in body growth, lipid metabolism, and the cell cycle pertaining to hepatosteatosis, fibrosis, and hepatocellular carcinoma. Finally, we discuss recent discoveries about the role of GH-STAT5 in sex-specific gene expression and bile acid, steroid, and drug metabolism.

Effects of mixtures of persistent organic pollutants (POPs) derived from cod liver oil on H295R steroidogenesis

Crude cod liver oil and liver oil supplements are consumed as a source of vitamin A, D and polyunsaturated fatty acids; during winter and early pregnancy. Crude cod liver oil however constitutes a considerable source of persistent organic pollutants (POPs). This paper aimed at characterizing and quantifying the influence of POP mixtures extracted from three different steps in the cod liver oil industrial process on hormone production and the expression of steroidogenesis-related genes in H295R cells. Exposure to extracts from crude cod liver oil and from its industrial waste increased progesterone (P4), cortisol (Cort), testosterone (T) and estradiol (E2) production; and among others, the expression of MC2R, CYP11B1 and HSD3B2 genes. Observed effects after exposure to pharmaceutical cod liver oil extract were considerably lower. The type of effects on gene expression and hormone production were similar to those induced by forskolin and PCBs, the latter being the major contaminants within the extracts. Additional research is required to further unveil the mechanisms behind the observed steroidogenic effects and to assess whether the potential risk might outweigh the potential benefits of crude and processed cod liver oil consumption.

Modulation of steroidogenic gene expression and hormone synthesis in H295R cells exposed to PCP and TCP

Chlorophenols (CPs) have been suspected to disrupt the endocrine system and thus affect human and wildlife reproduction but less is known about the underlying mechanism. In this study, we investigated the effects of pentachlorophenol (PCP) and 2,4,6-trichlorophenol (TCP) on human adrenocortical carcinoma cell line (H295R). The H295R cells were exposed to environmentally relevant concentration (0.0, 0.4, 1.1, 3.4μM) of PCP and TCP for 48h, and expression of specific genes involved in steroidogenesis, including cytochrome P450 (CYP11A, CYP17, CYP19), 3βHSD2, 17βHSD4 and StAR was quantitatively measured using real-time polymerase chain reaction. The selected gene expressions were significantly down-regulated compared with those in the control group. Exposure to PCP and TCP significantly decreased production of both testosterone (T) and 17β-estradiol (E2). Furthermore, a dose-dependent decrease of cellular cAMP was observed in H295R cells exposed to both PCP and TCP. A time-course study revealed that the observed selected steroidogenic gene expressions and protein abundance (StAR) are consistent with reduced cellular cAMP concentrations. The results showed that PCP and TCP may inhibit steroidogenesis by disrupting cAMP signaling. The research indicates that H295R cells can be used as an in vitro model for endocrine disruption assay for chlorophenols and the mechanism involvement of disturbing cAMP signaling.

Expression of the ACTH receptor, steroidogenic acute regulatory protein, and steroidogenic enzymes in canine cortisol-secreting adrenocortical tumors

Studies of human adrenocortical tumors (ATs) causing Cushing's syndrome suggest that hypersecretion of cortisol is caused by altered expression of steroidogenic enzymes and that steroidogenesis can only be maintained when there is expression of the ACTH receptor (ACTH-R). Here we report the screening for the mRNA expression of the ACTH-R, steroidogenic acute regulatory protein (StAR), cholesterol side-chain cleavage enzyme, 3β-hydroxysteroid dehydrogenase, 21-hydroxylase (all in 38 cortisol-secreting ATs), 17α-hydroxylase, and 11β-hydroxylase (both in 28 cortisol-secreting ATs). Real-time PCR (RT-PCR) was applied in all samples and was compared with that in normal canine adrenal glands. Messenger-RNA encoding StAR, steroidogenic enzymes, and ACTH-R were present in both normal adrenal glands and cortisol-secreting ATs. The amounts of mRNA encoding StAR and enzymes of the steroidogenic cluster needed for cortisol production did not differ significantly between either adenomas or carcinomas and normal adrenal glands. The amount of mRNA encoding ACTH-R was significantly lower in carcinomas than in normal adrenal glands (P = 0.008). In conclusion, RT-PCR analysis revealed no overexpression of StAR and steroidogenic enzymes in canine cortisol-secreting ATs. Significant downregulation of ACTH-R in carcinomas might be associated with the malignant character of the AT.

Serum estrogen and tumor-positive estrogen receptor-alpha are strong prognostic classifiers of non-small-cell lung cancer survival in both men and women

The role of tumor estrogen receptors (ERs) and serum estrogen in lung cancer is inconclusive. We investigated the hypothesis that ERs and functional single-nucleotide polymorphisms in the estrogen biosynthesis pathway are associated with poorer lung cancer survival. Lung cancer patients (n = 305) from a National Cancer Institute-Maryland (NCI-MD) case-case cohort in the Baltimore metropolitan area were used as a test cohort. To validate, 227 cases from the NCI-MD case-control cohort and 293 cases from a Norwegian lung cancer cohort were studied. Information on demographics, tobacco and reproductive histories was collected in an interviewer-administered questionnaire. Serum estrogen, progesterone, tumor messenger RNA expression of hormone receptors and germ line DNA polymorphisms were analyzed for associations with lung cancer survival. Patients in the highest tertile of serum estrogen had worse survival in all three cohorts (P combined < 0.001). Furthermore, the variant allele of estrogen receptor alpha (ER-α) polymorphism (rs2228480) was significantly associated with increased tumor ER-α levels and worse survival in all three cohorts [hazard ratio (HR) = 2.59, 95% confidence interval (CI): 1.20- 4.01; HR = 1.76, 95% CI: 1.08-2.87 and HR = 2.85, 95% CI: 1.31-4.36). Other polymorphisms associated with lower serum estrogen correlated with improved survival. Results were independent of gender and hormone replacement therapy. We report a significant association of increased serum estrogen with poorer survival among lung cancer male and female patients. Understanding the genetic control of estrogen biosynthesis and response in lung cancer could lead to improved prognosis and therapy.

Salt-sensitive hypertension in circadian clock-deficient Cry-null mice involves dysregulated adrenal Hsd3b6

Malfunction of the circadian clock has been linked to the pathogenesis of a variety of diseases. We show that mice lacking the core clock components Cryptochrome-1 (Cry1) and Cryptochrome-2 (Cry2) (Cry-null mice) show salt-sensitive hypertension due to abnormally high synthesis of the mineralocorticoid aldosterone by the adrenal gland. An extensive search for the underlying cause led us to identify type VI 3beta-hydroxyl-steroid dehydrogenase (Hsd3b6) as a new hypertension risk factor in mice. Hsd3b6 is expressed exclusively in aldosterone-producing cells and is under transcriptional control of the circadian clock. In Cry-null mice, Hsd3b6 messenger RNA and protein levels are constitutively high, leading to a marked increase in 3beta-hydroxysteroid dehydrogenase-isomerase (3beta-HSD) enzymatic activity and, as a consequence, enhanced aldosterone production. These data place Hsd3b6 in a pivotal position through which circadian clock malfunction is coupled to the development of hypertension. Translation of these findings to humans will require clinical examination of human HSD3B1 gene, which we found to be functionally similar to mouse Hsd3b6.

Novel 3beta-hydroxysteroid dehydrogenases from gonads of the Nile tilapia: phylogenetic significance and expression during reproductive cycle

Multiple forms of 3beta-hydroxysteroid dehydrogenase/isomerase (3beta-HSD) and their differential tissue expression pattern have not been shown in any lower vertebrates. In the present study, we report cloning of two novel 3beta-HSDs and two variants from gonads of the Nile tilapia. 3beta-HSD cDNAs encode two peptides of 375 (3beta-HSD type-I/variant 1) and 367 (3beta-HSD type-II/variant 1) amino acid residues that share 31.9% homology. 3beta-HSD type-I/variant 1 shared high homology with other piscine counterparts while 3beta-HSD type-II/variant 1 exhibited homology to mammalian DeltaC27-3beta-HSD and multifunctional viral 3beta-HSD. The latter seems to be ancient form among vertebrates. Transiently transfected 3beta-HSDs' open reading frames in COS-7 cells converted exogenous pregnenolone/androsta-5-ene-3beta-17beta-diol to progesterone/testosterone. Tissue distribution pattern of 3beta-HSDs by RT-PCR revealed varied expression pattern. Northern blot analysis of 3beta-HSDs demonstrated steady or gradual rise in transcripts level at different gonadal stages. These data revealed the importance of novel 3beta-HSDs in teleosts and also provided phylogenetic significance.

Disruption in the expression and immunolocalisation of steroid receptors and steroidogenic enzymes in letrozole-induced polycystic ovaries in rat

The objective of the present study was to characterise the expression and tissue distribution of steroid receptors (oestrogen receptor-α and –β (ERα, ERβ), androgen receptor (AR) and progesterone receptor (PR)) and steroidogenic enzymes (P450 aromatase (P450arom), 3β-hydroxysteroid dehydrogenase (3β-HSD) and steroidogenic acute regulatory protein (StAR)) in letrozole-induced polycystic ovaries of rats. Changes in serum hormone levels, protein expression in whole ovaries by western blot analysis and protein localisation by immunohistochemistry were determined in female rats treated with the aromatase inhibitor letrozole and compared with controls in proestrous and diestrous rats. Increases in the serum LH, FSH and testosterone concentrations were observed in letrozole-treated rats whereas serum oestradiol and progesterone levels were reduced. Protein expression as analysed by western immunoblot was consistent with the immunohistochemical data. Letrozole treatment induced an increase in the expression of AR, StAR and 3β-HSD and a decrease in ERβ. ERα, PR and P450arom showed partial changes in relation to some cycle stages. These results indicate that cystogenesis in this experimental model is characterised by changes in steroid receptors and steroidogenic enzyme expression that may be essential to proper ovarian functioning and are in agreement with similar changes observed in women with PCOS.

Human 3beta-hydroxysteroid dehydrogenase types 1 and 2: Gene sequence variation and functional genomics

The 3beta-hydroxysteroid dehydrogenase/Delta(5)-Delta(4) isomerase isoenzymes 1 and 2 (HSD3B1 and HSD3B2) are membrane-bound enzymes that play essential roles in the biosynthesis of steroid hormones. Therefore, variation in the HSD3B1 and HSD3B2 genes might play a role in the pathophysiology of steroid hormone-related disease. We set out to systematically identify common polymorphisms and haplotypes in human HSD3B1 and HSD3B2. We identified 17 single nucleotide polymorphisms (SNPs) in HSD3B1 and 9 in HSD3B2 - the majority of which were not present in public databases - by resequencing human HSD3B1 and HSD3B2 using 240 DNA samples from four different ethnic groups (60 samples per group). Functional genomic studies of the five non-synonymous cSNPs in HSD3B1 and the one observed in HSD3B2 showed that two of these polymorphisms resulted in significant decreases in the quantity of enzyme protein expressed. However, none of the three non-synonymous SNPs located in areas encoding putative membrane-binding domains altered subcellular localization of the enzyme as determined by immunofluorescence microscopy. Finally, common variant haplotypes in the 5'-flanking regions of these genes showed significant cell line-dependent variation in their ability to drive transcription. In aggregate, these results provide a basis for study of the possible role in human disease of common genetic variation in HSD3B1 and HSD3B2.

The Steroid Hormone Biosynthesis Pathway as a Target for Endocrine-Disrupting Chemicals

Various chemicals found in the human and wildlife environments have the potential to disrupt endocrine functions in exposed organisms. Increasingly, the enzymes involved in the steroid biosynthesis pathway are being recognized as important targets for the actions of various endocrine-disrupting chemicals. Interferences with steroid biosynthesis may result in impaired reproduction, alterations in (sexual) differentiation, growth, and development and the development of certain cancers. Steroid hormone synthesis is controlled by the activity of several highly substrate-selective cytochrome P450 enzymes and a number of steroid dehydrogenases and reductases. Particularly aromatase (CYP19), the enzyme that converts androgens to estrogens, has been the subject of studies into the mechanisms by which chemicals interfere with sex steroid hormone homeostasis and function, often related to (de)feminization and (de)masculinazation processes. Studies in vivo and in vitro have focussed on ovarian and testicular function, with less attention given to other steroidogenic organs, such as the adrenal cortex. This review aims to provide a comprehensive overview of the state of knowledge regarding the mechanisms by which chemicals interfere with the function of steroidogenic enzymes in various tissues and organisms. The endocrine toxicities and mechanisms of action related to steroidogenesis of a number of classes of drugs and environmental contaminants are discussed. In addition, several potential in vitro bioassays are reviewed for their usefulness as screening tools for the detection of chemicals that can interfere with steroidogenesis. Analysis of the currently scattered state of knowledge indicates that still relatively little is known about the underlying mechanisms of interference of chemicals with steroidogenesis and their potential toxicity in steroidogenic tissues, neither in humans nor in wildlife. Considerably more detailed and systematic research in this area of (endocrine) toxicology is required for a better understanding of risks to humans and wildlife.

Effects of PCBs and MeSO2-PCBs on adrenocortical steroidogenesis in H295R human adrenocortical carcinoma cells

Some endocrine disrupting chemicals (EDCs) in the environment have been shown to exert their biological effects through interference with steroidogenesis. In this study, the potential effects of four selected polychlorinated biphenyl (PCB) congeners (PCB101, PCB110, PCB126 and PCB149) as well as several of their environmentally-relevant methylsulfonyl-(MeSO(2)-) PCB metabolites (3'-MeSO(2)-CB101, 4'-MeSO(2)-CB101, 4'-MeSO(2)-CB110, 3'-MeSO(2)-CB149 and 4'-MeSO(2)-CB149) on adrenocortical steroidogenesis were evaluated by in vitro bioassay based on the human adrenocortical carcinoma H295R cell line. The PCBs included in the study represented different structures and potential mechanisms of action. Cells were exposed for 48 h to 10 microM of each PCB congener in the presence or absence of 20% (w/w) of their corresponding MeSO(2)-PCB metabolite(s). After the chemical treatments, changes in mRNA expression of 11 steroidogenic genes (CYP11A, CYP11B1, CYP11B2, CYP17, CYP19, CYP21, 3beta-HSD1, 3beta-HSD2, 17beta-HSD1, StAR and HMGR) were quantified using molecular beacon-based real-time RT-PCR. Genes coding for enzymes involved in the later or final steps of steroid production (CYP11B1, CYP11B2, CYP19, 3beta-HSD1, 3beta-HSD2 and 17beta-HSD1) were up-regulated to various extents by most PCBs. The greatest transcriptional activations (2.8-29.9-fold) were elicited by PCB110 on CYP11B1, CYP11B2, 3beta-HSD2 and CYP19, and PCB149 on CYP11B1, 3beta-HSD1 and 17beta-HSD1. Increased expression of these steroidogenic genes might ultimately lead to a change in hormonal balance through excessive production of steroid hormones including aldosterone, cortisol and estradiol. In addition, co-treatment with 3'- and 4'-MeSO(2)-PCB149 resulted in a significant decrease in PCB149-induced 3beta-HSD1 and 17beta-HSD1 expression. This result indicates that some PCB congeners and their MeSO(2)-metabolites may affect steroidogenesis via different mechanisms. Overall, these findings suggest that PCBs and PCB metabolites can affect regulation of adrenocortical steroidogenesis.

Metabolism of the 16-androstene steroids in primary cultured porcine hepatocytes

The hepatic metabolism of the 16-androstene steroids was investigated using isolated porcine hepatocytes. This study demonstrated that the liver is capable of producing both phase I and phase II steroid metabolites from 16-androstene steroid precursors. 16-Androstene metabolites were recovered by solid-phase extraction and identified by gas chromatography-mass spectrometry (GC-MS). When 5alpha-androstenone was provided as a substrate, both 3beta- and 3alpha-androstenol were produced as well as a metabolite that showed evidence of hydroxylation. Incubations with the various 16-androstene steroids produced metabolic profiles which suggested that the major role of the liver is phase II conjugation. Sulfoconjugated 16-androstene steroids included androstadienol, 5alpha-androstenone, 3beta-, 3alpha-androstenol, and possibly the hydroxylated metabolite of 5alpha-androstenone. It was determined that hydroxysteroid sulfotransferase (HST) is the likely candidate for the sulfoconjugation of the 16-androstene steroids within the liver. Despite the capacity of the hepatocytes to sulfoconjugate the 16-androstene steroids, the principle metabolites produced from incubations with 5alpha-androstenone, 3beta-, and 3alpha-androstenol were glucuronide conjugates, accounting for approximately 68% of all phase II metabolism. These findings underline the importance of steroid conjugation and suggest that hepatic metabolism of the 16-androstene steroids may influence the levels of 5alpha-androstenone present in the circulation, and thus, capable of accumulating in fat.

Molecular biology of the 3beta-hydroxysteroid dehydrogenase/delta5-delta4 isomerase gene family

The 3beta-hydroxysteroid dehydrogenase/Delta(5)-Delta(4) isomerase (3beta-HSD) isoenzymes are responsible for the oxidation and isomerization of Delta(5)-3beta-hydroxysteroid precursors into Delta(4)-ketosteroids, thus catalyzing an essential step in the formation of all classes of active steroid hormones. In humans, expression of the type I isoenzyme accounts for the 3beta-HSD activity found in placenta and peripheral tissues, whereas the type II 3beta-HSD isoenzyme is predominantly expressed in the adrenal gland, ovary, and testis, and its deficiency is responsible for a rare form of congenital adrenal hyperplasia. Phylogeny analyses of the 3beta-HSD gene family strongly suggest that the need for different 3beta-HSD genes occurred very late in mammals, with subsequent evolution in a similar manner in other lineages. Therefore, to a large extent, the 3beta-HSD gene family should have evolved to facilitate differential patterns of tissue- and cell-specific expression and regulation involving multiple signal transduction pathways, which are activated by several growth factors, steroids, and cytokines. Recent studies indicate that HSD3B2 gene regulation involves the orphan nuclear receptors steroidogenic factor-1 and dosage-sensitive sex reversal adrenal hypoplasia congenita critical region on the X chromosome gene 1 (DAX-1). Other findings suggest a potential regulatory role for STAT5 and STAT6 in transcriptional activation of HSD3B2 promoter. It was shown that epidermal growth factor (EGF) requires intact STAT5; on the other hand IL-4 induces HSD3B1 gene expression, along with IL-13, through STAT 6 activation. However, evidence suggests that multiple signal transduction pathways are involved in IL-4 mediated HSD3B1 gene expression. Indeed, a better understanding of the transcriptional factors responsible for the fine control of 3beta-HSD gene expression may provide insight into mechanisms involved in the functional cooperation between STATs and nuclear receptors as well as their potential interaction with other signaling transduction pathways such as GATA proteins. Finally, the elucidation of the molecular basis of 3beta-HSD deficiency has highlighted the fact that mutations in the HSD3B2 gene can result in a wide spectrum of molecular repercussions, which are associated with the different phenotypic manifestations of classical 3beta-HSD deficiency and also provide valuable information concerning the structure-function relationships of the 3beta-HSD superfamily. Furthermore, several recent studies using type I and type II purified enzymes have elegantly further characterized structure-function relationships responsible for kinetic differences and coenzyme specificity.

Mitochondrial 3 beta-hydroxysteroid dehydrogenase (HSD) is essential for the synthesis of progesterone by corpora lutea: an hypothesis

In mouse ovaries, the enzyme 3 beta-hydroxysteroid dehydrogenase (HSD) is distributed between microsomes and mitochondria. Throughout the follicular phase of the estrous cycle, the HSD activity in microsomes is predominant; whereas, after LH stimulation, HSD activity during the luteal phase is highest in the mitochondria. The current study examined whether or not LH stimulation always results in an increase in mitochondrial HSD activity. This was accomplished by measuring the HSD activity in microsomal and mitochondrial fractions from ovaries of pregnant mice. These animals have two peaks of LH during gestation, and one peak of LH after parturition. It was found that mitochondrial HSD activity was highest after each peak of LH. It is proposed that mitochondrial HSD is essential for the synthesis of high levels of progesterone. The increase in HSD activity in mitochondria after LH stimulation occurs because: 1) LH initiates the simultaneous synthesis of HSD and the cholesterol side-chain cleavage enzyme (P450scc); and, 2) HSD and P450scc bind together to form a complex, which becomes inserted into the inner membrane of the mitochondria. High levels of progesterone are synthesized by mitochondrial HSD because: 1) the requisite NAD+ cofactor for progesterone synthesis is provided directly by the mitochondria, rather than indirectly via the rate limiting malate-aspartate shuttle; and, 2) the end-product inhibition of P450scc by pregnenolone is eliminated because pregnenolone is converted to progesterone.

Dehydroepiandrosterone metabolism by 3beta-hydroxysteroid dehydrogenase/Delta5-Delta4 isomerase in adult zebra finch brain: sex difference and rapid effect of stress

Dehydroepiandrosterone (DHEA) is a precursor to sex steroids such as androstenedione (AE), testosterone (T), and estrogens. DHEA has potent effects on brain and behavior, although the mechanisms remain unclear. One possible mechanism of action is that DHEA is converted within the brain to sex steroids. 3beta-Hydroxysteroid dehydrogenase/Delta5-Delta4 isomerase (3beta-HSD) catalyzes the conversion of DHEA to AE. AE can then be converted to T and estrogen within the brain. We test the hypothesis that 3beta-HSD is expressed in the adult brain in a region- and sex-specific manner using the zebra finch (Taeniopygia guttata), a songbird with robust sex differences in song behavior and telencephalic song nuclei. In zebra finch brain, DHEA is converted by 3beta-HSD to AE and subsequently to estrogens and 5alpha- and 5beta-reduced androgens. 3beta-HSD activity is highest in the diencephalon and telencephalon. In animals killed within 2-3 min of disturbance, baseline 3beta-HSD activity in portions of the telencephalon is higher in females than males. Acute restraint stress (10 min) decreases 3beta-HSD activity in females but not in males, and in stressed animals, telencephalic 3beta-HSD activity is greater in males than in females. Thus, the baseline sex difference is rapidly reversed by stress. To our knowledge, this is the first demonstration of 1) brain region differences in DHEA metabolism by 3beta-HSD, 2) rapid modulation of 3beta-HSD activity, and 3) sex differences in brain 3beta-HSD and regulation by stress. Songbirds are good animal models for studying the regulation and functions of DHEA and neurosteroids in the nervous system.

DAX1 and its network partners: exploring complexity in development

DAX1 encoded by NR0B1, when mutated, is responsible for X-linked adrenal hypoplasia congenita (AHC). AHC is due to failure of the adrenal cortex to develop normally and is fatal if untreated. When duplicated, this gene is associated with an XY sex-reversed phenotype. DAX1 expression is present during development of the steroidogenic hypothalamic-pituitary-adrenal-gonadal (HPAG) axis and persists into adult life. Despite recognition of the crucial role for DAX1, its function remains largely undefined. The phenotypes of patients and animal models are complex and not always in agreement. Investigations using cell lines have proved difficult to interpret, possibly reflecting cell line choices and their limited characterization. We will review the efforts of our group and others to identify appropriate cell lines for optimizing ex vivo analysis of NR0B1 function throughout development. We will examine the role of DAX1 and its network partners in development of the hypothalamic-pituitary-adrenal/gonadal axis (HPAG) using a variety of different types of investigations, including those in model organisms. This network analysis will help us to understand normal and abnormal development of the HPAG. In addition, these studies permit identification of candidate genes for human inborn errors of HPAG development.

Genetic profiling defines the xenobiotic gene network controlled by the nuclear receptor pregnane X receptor

The orphan nuclear receptor pregnane X receptor (PXR) is essential for the transcriptional regulation of hepatic xenobiotic enzymes including the cytochrome 3A isoenzymes. These enzymes are central to the catabolism and clearance of most endogenous sterol metabolites (endobiotics) and a vast diversity of foreign compounds (xenobiotics) including pharmaceuticals, pesticides, and toxins encountered through diet and environmental exposure. To explore a broader role of PXR in the mammalian xenobiotic response, we have conducted a unique microarray gene profiling analysis on liver samples derived from PXR knockout mice and mice expressing a constitutively active variant, VP-hPXR. This genetically guided expression analysis enables targeting and restriction of the PXR response to liver, and is devoid of side effects resulting from drugs and their metabolites. As with pharmacological studies, receptor-dependent genes include both phase I and phase II metabolic enzymes, as well as certain drug and anion transporters as principal PXR targets. Moreover, comparative analysis of data from both genetic and pharmacological arrays reveals a core network that represents a genetic description of the xenobiotic response.

Adrenocortical zonation and ACTH

The clear morphological distinction between the cells of the different adrenocortical zones has attracted speculation and experiment to interpret their functions and the ways in which they are regulated. Considerable data have been produced in recent years that has benefited a fuller understanding of the processes of steroidogenesis and of cell proliferation at the molecular level. This now enables the reexamination of earlier concepts. It is evident that there is considerable species variation, and this article, dealing mainly with the rat, reaches conclusions that do not necessarily apply to other mammals. In the rat adrenal, however, the evidence suggests that the greatest differences between the functions of the zones are between the glomerulosa and the fasciculata. Here the sometimes all-or-nothing demarcation in their complement of components associated with steroidogenesis or with cell proliferation suggests a stark division of labor. In this model the fasciculata is the main engine of steroid hormone output and the glomerulosa is the site of cell proliferation, recruitment, and differentiation. Regulating these functions are angiotensin II and other paracrine components that modulate and maintain the glomerulosa, and ACTH, that maintains the fasciculata, and recruits new fasciculata cells by transformation of proliferating glomerulosa cells. Grafted onto this mostly vegetative function of the glomerulosa is CYP11B2, limited to just a fraction of the outer glomerulosa in rats on a normal laboratory diet and generating aldosterone (and 18-hydroxycorticosterone) from precursors whose origin is not, from the evidence summarized here, very clear, but may include the fasciculata, directly or indirectly. The biosynthesis of aldosterone in the rat certainly requires reinterpretation.

Gas chromatography/mass spectrometry characterization of corticosteroid metabolism in human immortalized keratinocytes

To continue our studies on the cutaneous expression of a proopiomelanocortin/corticotropin-releasing hormone system, we investigated whether this is accompanied by adrenal-type enzymatic activity. Immortalized cultured human keratinocytes were incubated with radiolabeled corticosteroids. Analysis by thin-layer chromatography showed rapid transformation of both progesterone and deoxycorticosterone; one of the progesterone metabolites migrated at the same rate as deoxycorticosterone. Gas chromatography/mass spectrometry further identified as major species of deoxycorticosterone metabolites 3beta,6alpha,21-trihydroxy-5alpha-pregnan-20-one, 3alpha,6alpha,21-trihydroxy-5alpha-pregnan-20-one, and 3alpha5alpha- and 3beta5alpha-tetrahydrodeoxycorticosterone. Minor metabolites were 3alpha,21-dihydroxy-5-pregnen-20- one (3alphaDelta5-21-OHpregnenolone), 3beta,21-dihydroxy-5-pregnen-20-one (3betaDelta5-21-OHpregnenolone), 3alpha,21-dihydroxy-4-pregnen-20-one (3alphaDelta4-21-OHpregnenolone), 6-hydroxy-dihydrodeoxycorticosterone, and two 5-dihydrodeoxycorticosterone species. Thus, in addition to sex steroids keratinocytes also actively metabolize corticosteroids along similar enzymatic pathways. The surprising detection of 3alphaDelta5-21-OHpregnenolone and 3 betaDelta5-21-OHpregnenolone, indicating Delta4-ketosteroids to Delta5-hydroxysteroids conversion, provides strong evidence for the occurrence, at least in human keratinocytes, of isomerase activity that allows the reaction to proceed in reverse of its usual direction. As skin expresses 3alpha/beta-hydroxysteroid dehydrogenase/Delta5-Delta4 isomerases, cutaneous reactions catalyzed by these enzymes must be reversible. In conclusion, besides elements of the corticotropin-releasing hormone/proopiomelanocortin system human keratinocytes show high levels of corticosteroid metabolizing activity. Moreover, the wide array of steroid products generated from a single substrate indicates serial progressive conversion involving 5alpha-reductase, 6alpha-hydroxylase, 3alpha/beta-hydroxysteroid dehydrogenase, and reverse Delta4minus signDelta5 isomerase enzymes. As distinct from the adrenal cortex, production of A, B, Aldo, 18OHdeoxycorticosterone, or F in keratinocytes was absent or below limits of detectability.

Conditionally immortalized adrenocortical cell lines at undifferentiated states exhibit inducible expression of glucocorticoid-synthesizing genes

To facilitate studies on differentiation of adrenocortical cells and regulation of steroidogenic genes, we established cell lines from adrenals of adult transgenic mice harboring a temperature-sensitive large T-antigen gene of simian virus 40. Adrenal glands of the mice exhibited normal cortical zonation including a functionally undifferentiated cell-layer between the aldosterone-synthesizing zona glomerulosa cells and the corticosterone-synthesizing zona fasciculata cells. At a permissive temperature (33 degrees C), established cell lines AcA201, AcE60 and AcA101 expressed steroidogenic genes encoding steroidogenic factor-1, cholesterol side-chain cleavage P450scc, and steroidogenic acute regulatory protein, which are expressed throughout adrenal cortices and gonads. Genes encoding 3 beta-hydroxysteroid dehydrogenase and steroid 21-hydroxylase P450c21, which catalyze the intermediate steps for syntheses of both aldosterone and corticosterone, were inducible in the three cell lines in temperature- and/or dibutyryl cAMP-dependent manners. Notably, these cell lines displayed distinct expression patterns of the steroid 11 beta-hydroxylase P45011 beta gene responsible for the zone-specific synthesis of corticosterone. AcA201 cells expressed the P45011 beta gene at 33 degrees C, showing the property of the zona fasciculata cells, while AcE60 cells expressed it upon a shift to a nonpermissive temperature (39 degrees C). On the other hand, AcA101 expressed the P45011 beta gene at 39 degrees C synergistically with exposure to dibutyryl cAMP. None of these clones express the zona glomerulosa-specific aldosterone synthase P450aldo gene under the conditions we tested. These results show that AcE60 and AcA101 cells display a pattern of the steroidogenic gene expression similar to that of the undifferentiated cell-layer and are capable of differentiating into the zona fasciculata-like cells in vitro.

Dynamic changes in gene expression along the rat epididymis

In the epididymis a series of complex, sequential events transform immature, spermatozoa into mature, motile sperm with fertilizing ability. These events are not intrinsic to germ cells but rather are a direct result of exposure to, and interaction with, the environment created by the epididymal epithelium. Regional differences along the epididymis are essential in the establishment of the environment required for sperm maturation. Although parts of this process have been identified, the molecular basis for the segment-specific differences and how they contribute to the process of sperm maturation, are not yet resolved. The identification of genes expressed in a region-specific manner will provide valuable insight into the functional differences between the regions. To characterize gene expression in the different regions of the epididymis, microarrays containing 1176 rat cDNAs were used to examine gene expression in the initial segment, caput, corpus, and cauda epididymidis of the adult Brown Norway rat. Overall, the cauda epididymidis expressed the most genes and the corpus epididymidis the fewest. A small percentage of genes (3%) were expressed highly (greater than fivefold the average expression on the array) along the tissue. Segment-specific gene expression for genes expressed at high levels was observed in all epididymal segments except the corpus epididymidis. Of the genes on the array, 36% were expressed in all four epididymal segments; expression changes that were a minimum of twofold in either direction between adjacent segments are discussed. The expression of cathepsins and oxidative stress-related genes was investigated. Six of the eight cathepsins on the array (B, C, E, H, L, and K) were expressed above twofold background and showed different levels of expression along the duct with cathepsin K showing the most dramatic change (i.e., a decrease of 87% between the initial segment and the corpus epididymidis). There was also differential expression along the epididymis of many genes associated with oxidative stress defenses. Using the power of expression array technology, we have identified novel transcripts expressed in a segment-specific manner and been able to assess how the expression of several selected gene families is modulated along the epididymis.

Characterization of a steroidogenic factor-1-binding site found in promoter of sterol carrier protein-2 gene

Sterol carrier protein-2 (SCP2) is thought to mediate intracellular cholesterol transport in steroidogenic tissues. To elucidate the mechanism underlying the expression of this gene, a 300-bp fragment of the SCP2 promoter was cloned and analyzed for regulatory motifs. This promoter region contained a SF-1 binding motif, three activator protein-1 elements, an insulin response element, and a peroxisomal proliferator response element. The putative SF-1 binding region reacted with recombinant SF-1 DNA-binding domain in a mobility shift assay. The SCP2 promoter fragment was linked to a luciferase reporter gene and cotransfected in the presence or absence of SF-1 into HTB-9 cells. The results indicated that SF-1 was able to increase SCP2 promoter activity, an effect that was enhanced by cAMP. Similar results were obtained when the SCP2 promoter construct was cotransfected into Y1 cells. Cotransfection studies carried out in Kin 8 cells, a Y1 cell line with a mutation that prevents cAMP activation of PKA, revealed that a functional PKA is required for cAMP induction of SCP2 gene transcription. These results demonstrated that SF-1 confers cAMP responsiveness to the SCP2 promoter suggesting that SF-1 activation may be critical in regulation of this cholesterol transport protein.

Crucial role of cytokines in sex steroid formation in normal and tumoral tissues

There is evidence suggesting that local intracrine formation of sex steroids from inactive precursors, dehydroepiandrosterone (DHEA), its sulfate (DHEA-S) and 4-androstenedione (4-DIONE) plays an important role in the regulation of growth and function of peripheral target tissues. Moreover, human solid tumors are often infiltrated by stromal/immune cells secreting a wide spectra of cytokines. These cytokines might in turn regulate the activity of both immune and neoplastic cells. Our data demonstrate that the potent regulatory effects of interleukin-4 (IL-4) and IL-6 on both estrogenic and androgenic 17beta-HSD/KSR activities in breast cancer cells depend on the cell-specific gene expression of various types of 17beta-HSD/KSR enzymes. However, in both estrogen-receptor (ER)-positive (ZR-75-1, T-47D) and ER-negative (MDA-MB-231, BT-20) human breast cancer cells, exposure to IL-4 and IL-13 caused a rapid and potent induction of 3beta-HSD type 1 gene expression. Such an induction was also observed in normal human mammary and prostate epithelial cells in primary culture as well as in human HaCaT immortalized keratinocytes, ME-180 cervix cancer cells, and HT-29 colon cancer cells. The DNA-binding activity of Stat6, a member of the Signal Transducers and Activators of Transcription gene family, was activated after a 30 min exposure to IL-4 in all the cell types where IL-4 induced 3beta-HSD expression, but not in those that failed to respond to IL-4. Our data therefore suggest that IL-4 and IL-13 may play a role in the biosynthesis of active sex steroids from the inactive adrenal steroid DHEA, not only in breast cells but also in various cell types derived from peripheral target tissues.

Equine P450 cholesterol side-chain cleavage and 3 beta-hydroxysteroid dehydrogenase/delta(5)-delta(4) isomerase: molecular cloning and regulation of their messenger ribonucleic acids in equine follicles during the ovulatory process

The preovulatory LH rise is the physiological trigger of follicular luteinization, a process during which the synthesis of progesterone is markedly increased. To study the control of follicular progesterone biosynthesis in mares, the objectives of this study were to clone and characterize the equine cholesterol side-chain cleavage cytochrome P450 (P450(scc)) and 3 beta-hydroxysteroid dehydrogenase/Delta(5)-Delta(4)-isomerase (3 beta-HSD), and describe the regulation and cellular localization of their transcripts in equine follicles during hCG-induced ovulation. Complementary DNA cloning and primer extension analyses revealed that the equine P450(scc) transcript is composed of a 5'-untranslated region (UTR) of 52 nucleotides, an open reading frame (ORF) of 1560 nucleotides, and a 3'-UTR of 225 nucleotides, whereas the equine 3 beta-HSD mRNA consists of a 5'-UTR of 61 nucleotides, an ORF of 1119 nucleotides, and a 3'-UTR of 432 nucleotides. The equine P450(scc) and 3 beta-HSD ORF encode 520 and 373 amino acid proteins, respectively, that are highly conserved (68-79% identity) when compared to homologs of other mammalian species. Northern blot analyses were performed with preovulatory follicles isolated 0, 12, 24, 30, 33, 36, and 39 h post-hCG, and corpora lutea obtained on day 8 of the cycle. Results showed that levels of P450(scc) mRNA in follicular wall (theca interna with attached granulosa cells) decreased after hCG treatment (30-39 h versus 0 h post-hCG, P: < 0.05), and increased again after ovulation to reach their highest levels in corpora lutea (P: < 0.05). Northern blots on isolated cellular preparations revealed that theca interna was the predominant site of P450(scc) expression in follicles prior to hCG (P: < 0.05). However, transcript levels decreased in theca interna between 30-39 h (P: < 0.05) and increased in granulosa cells at 39 h (P: < 0.05), making the granulosa cell layer the predominant site of P450(scc) expression at the end of the ovulatory process. A different pattern of regulation was observed for 3 beta-HSD, as transcript levels remained constant throughout the luteinization process (P: > 0.05). Also, in contrast to other species, expression of 3 beta-HSD mRNA in equine preovulatory follicles was localized only in granulosa cells and not in theca interna. Thus, this study characterizes for the first time the complete structure of equine P450(scc) and 3 beta-HSD mRNA and identifies novel patterns of expression and regulation of these transcripts in equine follicles prior to ovulation.

A new insight into the molecular basis of 3beta-hydroxysteroid dehydrogenase deficiency

Classical 3beta-hydroxysteroid dehydrogenase/delta5-delta4 isomerase (3beta-HSD) deficiency is a rare form of congenital adrenal hyperplasia that impairs steroidogenesis in both the adrenals and gonads resulting from mutations in the HSD3B2 gene, causing varying degrees of salt-loss in both sexes and incomplete masculinization of the external genitalia in genetic males. To date a total of 34 mutations (including 5 frameshift, 4 nonsense, 1 in-frame deletion, 1 splicing and 23 missense mutations) have been identified in the HSD3B2 gene. Results from functional charaterization studies of the mutant proteins agrees with the prediction that no functional type II 3beta-HSD isoenzyme is expressed in the adrenals and gonads of the patients with the severe salt-losing form, whereas the nonsalt-losing form causes an incomplete loss in enzymatic activity, thereby leaving sufficient enzymatic activity to prevent salt loss. Recent studies have highlighted the fact that various mutations appear to have a drastic effect upon the stability of the protein, therefore providing molecular evidence of a new mechanism involved in classical 3beta-HSD deficiency. Finally, the functional characterization of the missense mutations known to be involved in this autosomal recessive disorder provides valuable information concerning the structure-function relationships of the 3beta-HSD enzyme superfamily.

Steroidogenic factor-1 mediates cyclic 3',5'-adenosine monophosphate regulation of the high density lipoprotein receptor

The high density lipoprotein (HDL) receptor mediates the uptake of cholesterol and cholesteryl esters, substrates for steroidogenesis, from an HDL particle in the adrenal gland and gonads. We report here that treatment of rat luteal cells with 1 mM (Bu)2cAMP for 24 h dramatically induced (118-fold) HDL receptor messenger RNA levels. The rat HDL receptor promoter contains a steroidogenic factor-1 (SF-1)-binding site (SFBd; 5'-TCAAGGCC-3') through which SF-1 protein binds and activates transcription of this gene in both human HTB9 bladder carcinoma and mouse Y1 tumor cells, an effect that is enhanced by cAMP. These observations demonstrate that this motif is required for both basal and cAMP-induced regulation of the HDL receptor gene. Cotransfection studies in Kin 8 cells, a Y1 cell line resistant to cAMP activation as a result of a mutation in the protein kinase A (PKA) regulatory subunit, showed that a functional PKA is required for cAMP induction of HDL receptor gene transcription. Deleting the activation function-2 domain (amino acids 448-461) or mutating Ser430, a potential consensus phosphorylation site for PKA in the SF-1 protein, decreased both basal and cAMP-induced activation of the HDL receptor promoter. These data suggest that these regions within the SF-1 protein are required for both basal and cAMP-induced regulation of the HDL receptor gene. The mediation of cAMP responsiveness of the HDL receptor gene by SF-1 suggests how important this trans-acting factor is in steroid hormone synthesis by assuring that all required elements (substrate and enzymes) are present when they are needed for maximal steroid production.