Cis-regulatory polymorphism at fiz ecdysone oxidase contributes to polygenic evolutionary response to malnutrition in Drosophila

We investigate the contribution of a candidate gene, fiz (fezzik), to complex polygenic adaptation to juvenile malnutrition in Drosophila melanogaster. Experimental populations maintained for >250 generations of experimental evolution to a nutritionally poor larval diet (Selected populations) evolved several-fold lower fiz expression compared to unselected Control populations. Here we show that this divergence in fiz expression is mediated by a cis-regulatory polymorphism. This polymorphism, originally sampled from a natural population in Switzerland, is distinct from a second cis-regulatory SNP previously identified in non-African D. melanogaster populations, implying that two independent cis-regulatory variants promoting high fiz expression segregate in non-African populations. Enzymatic analyses of Fiz protein expressed in E. coli demonstrate that it has ecdysone oxidase activity acting on both ecdysone and 20-hydroxyecdysone. Four of five fiz paralogs annotated to ecdysteroid metabolism also show reduced expression in Selected larvae, implying that malnutrition-driven selection favored general downregulation of ecdysone oxidases. Finally, as an independent test of the role of fiz in poor diet adaptation, we show that fiz knockdown by RNAi results in faster larval growth on the poor diet, but at the cost of greatly reduced survival. These results imply that downregulation of fiz in Selected populations was favored by selection on the nutritionally poor diet because of its role in suppressing growth in response to nutrient shortage. However, they suggest that fiz downregulation is only adaptive in combination with other changes evolved by Selected populations, which ensure that the organism can sustain the faster growth promoted by fiz downregulation.

The glucocorticoid-activating enzyme 11β-hydroxysteroid dehydrogenase type 1 catalyzes the activation of testosterone

Testosterone biosynthesis from its precursor androstenedione is thought to be exclusively catalysed by the 17β-hydroxysteroid dehydrogenases-HSD17B3 in testes, and AKR1C3 in the ovary, adrenal and peripheral tissues. Here we show for the first time that the glucocorticoid activating enzyme 11β-hydroxysteroid dehydrogenase type 1 (HSD11B1) can also catalyse the 17β-reduction of androstenedione to testosterone, using a combination of in vitro enzyme kinetic assays, mathematical modelling, and molecular docking analysis. Furthermore, we show that co-expression of HSD11B1 and AKR1C3 increases testosterone production several-fold compared to the rate observed with AKR1C3 only, and that HSD11B1 is likely to contribute significantly to testosterone production in peripheral tissues.

Effects of phenolic compounds on 3β-hydroxysteroid dehydrogenase activity in human and rat placenta: Screening, mode of action, and docking analysis

Human 3β-hydroxysteroid dehydrogenase type I (HSD3B1) and rat type IV (HSD3B4) in placentas catalyze the conversion of pregnenolone to progesterone, which plays a key role in maintaining pregnancy. Many phenolic compounds potentially inhibit HSD3B in placentas as endocrine disruptors. In this study, the effects of 16 phenolic compounds on the activity of human HSD3B1 and rat HSD3B4 were determined and the structure-activity relationship was compared. HSD3B1 in human placental microsomes and HSD3B4 in rat placental microsomes were used to measure their activities and pregnenolone and NAD⁺ were used as substrates. Of the 16 phenolic compounds, 4-nonylphenol, pentabromophenol, and 2-bromophenol resulted in residual human HSD3B1 activity lower than 50 % and 4-nonylphenol and pentabromophenol resulted in residual rat HSD3B4 activity lower than 50 %. 4-Nonylphenol, pentabromophenol, and 2-bromophenol were mixed inhibitors of human HSD3B1, with Ki values of 2.31, 3.58 and 4.86 µM, respectively, while 4-nonylphenol and pentabromophenol were noncompetitive inhibitors of rat HSD3B4 with Ki values of 20.86 and 141.8 µM. Molecular docking showed that 4-nonylphenol, pentabromophenol, and 2-bromophenol docked to the active sites of human HSD3B1 and rat HSD3B4, and the shift of residue S125 in human HSD3B1 to T125 in rat HSD3B4 could explain the species-dependent difference in their inhibitory potency and mode of action. This study demonstrates that 4-nonylphenol, pentabromophenol, and 2-bromophenol are mixed inhibitors of human placental HSD3B1, while 4-nonylphenol and pentabromophenol are noncompetitive inhibitors of rat HSD3B4, possibly blocking the placental steroidogenesis.

Inflammatory linear verrucous epidermal nevus (ILVEN) encompasses a spectrum of inflammatory mosaic disorders

BACKGROUND

Inflammatory linear verrucous epidermal nevus (ILVEN) is a rare skin disease characterized by pruritic erythematous scaly plaques distributed along the lines of Blaschko. Two cases of ILVEN with CARD14 mutations and one case with a GJA1 mutation have been previously reported.

OBJECTIVE

To elucidate the genetic cause of a cohort of patients diagnosed based on clinical and histopathological evaluation with ILVEN.

METHODS

We recruited patients diagnosed with ILVEN based on clinical and histopathological criteria. Exome sequencing of affected skin with or without blood/saliva was performed and germline and somatic pathogenic variants were identified.

RESULTS

Five patients were enrolled. All had skin lesions from birth or early childhood. Two patients developed psoriasis vulgaris after the diagnosis of ILVEN. The first had a germline heterozygous CARD14 mutation and a post-zygotic hotspot mutation in KRT10. The histopathologic evaluation did not show epidermolytic hyperkeratosis. The second had a post-zygotic hotspot mutation in HRAS. Her ILVEN became itchy once psoriasis developed. One patient was re-diagnosed with linear porokeratosis based on a germline mutation in PMVK and a post-zygotic second-hit mutation. Two patients were re-diagnosed with congenital hemidysplasia with ichthyosiform nevus and limb defect nevus based on germline NSDHL mutations.

CONCLUSION

ILVEN is a clinical descriptor for a heterogenous group of mosaic inflammatory disorders. Genetic analysis has the potential to more precisely categorize ILVEN and permits pathogenesis-directed therapies in some cases.

Absence of some cytochrome P450 (CYP) and hydroxysteroid dehydrogenase (HSD) enzymes in hagfishes

Corticosteroids are synthesized from cholesterol by steroidogenic enzyme catalysts belonging to two main families: the cytochrome p450s (CYPs) and hydroxysteroid dehydrogenases (HSDs). The action of these steroidogenic enzymes allows the genesis of the terminal active corticosteroids 11-deoxycortisol (S), 1ɑ-hydroxycorticosterone (1α-OH-B), or cortisol in different fish species. However, for Cyclostomes like hagfishes, the terminal corticosteroid is still undefined. In this study, we examined the presence or absence of CYPs and HSDs as traits in fishes to gain insight about the primary corticosteroid synthesis pathways of the hagfishes. We used published cytochrome c oxidase I (COXI) amino acid sequences to construct a phylogeny of fishes and then mapped the CYPs and HSDs as morphological traits onto the tree to predict the ancestral character states through ancestral character reconstruction (ACR). There is a clear phylogenetic signal for CYP (i.e., CYP11a1, 17, 21, and 11b) and HSD (i.e., 11-βHSD and 3β-HSD) derivatives of interest throughout the more derived fishes. Using trait-based ACR, we also found that hagfishes possess genes for 3β-HSD, CYP11a1, CYP17, and CYP21. Importantly, the presence of CYP21 implies that hagfish can synthesize 11-deoxycorticosterone (11-DOC) and S. Previous research demonstrated that despite hagfish having CYP21, neither 11-DOC nor S could be detected in hagfish. This discrepancy between the presence of steroidogenic enzymes and products brings into question the expression and/or function of CYP21 in hagfishes.

Prognosis and clinical characteristics of patients with 3β-hydroxy-Δ5-C27-steroid dehydrogenase deficiency diagnosed in childhood: A systematic review of the literature

OBJECTIVES

3β-hydroxy-Δ5-C27-steroid dehydrogenase deficiency is a rare autosomal recessive condition. So far fewer than 100 cases have been reported and the factors affecting the prognosis are not yet established. The objective of this study is to explore a possible prediction of the outcome of this rare condition.

METHODS

This review was undertaken and reported in accordance with the preferred reporting items for systematic review and meta-analyses guidelines. Demographics, clinical features, gene data, treatment strategies and prognoses at the last follow-up were extracted and summarized. Patients were divided into 2 groups (alive with native liver and liver transplantation/died). Risk factors for the different clinical features were identified.

RESULTS

87 patients that were taken from 7 case reports and 9 case series were included. 38 (38/63, 63.0%) of them presented initial symptoms when they were younger than 1 month and 55 (55/63, 87.3%) less than 1 year. There is a larger proportion of patients younger than 1 month or 1 year at the age of symptom onset in the liver transplantation /died group than patients in alive with the native liver group. The majority of patients (53/62, 85.5%) were diagnosed before the age of 5 year. In all cases, 65 (predicted) pathogenic variants have been identified. Over 70% of patients carried an HSD3B7 variant on exon 1, 4, 5 or 6. 71 (81.6%) were alive at the last follow-up, 16 (18.4%) underwent liver transplantation or died. No significance was found between the group alive with native liver and group liver transplantation /died.

CONCLUSION

Age of onset of the symptoms may be a potential factor that determines the outcome of patients with 3β-HSD deficiency, patients presented with symptoms and signs at an age younger than 1 month or even 1 year may have a worse prognosis. Since there is no difference between clinical outcome and zygosity of gene mutation, we recommend a further study about any possible relationship between mutation site and clinical characteristics or prognosis.

Proteomic analysis reveals proteins and pathways associated with declined testosterone production in male obese mice after chronic high-altitude exposure

OBJECTIVE

Obesity is common in highland areas owing to lifestyle alterations. There are pieces of evidence to suggest that both obesity and hypoxia may promote oxidative stress, leading to hypogonadism in males. These findings indicate an increased risk of hypogonadism in obese males following hypoxia exposure. However, the mechanisms underlying the disease process remain unclear. The current study aims to explore the mechanism of testosterone production dysfunction in obese male mice exposed to a chronic high-altitude hypoxia environment.

METHODS

An obese male mouse model was generated by inducing obesity in mice via a high-fat diet for 14 weeks, and the obese mice were then exposed to a high-altitude hypoxia environment for 24 days. Sera and testicular tissues were collected to detect serum lipids, sex hormone level, and testicular oxidative stress indicators. Morphological examination was performed to assess pathological alterations in testicular tissues and suborganelles in leydig cells. Proteomic alterations in testicular tissues were investigated using quantitative proteomics in Obese/Control and Obese-Hypoxia/Obese groups.

RESULTS

The results showed that chronic high-altitude hypoxia exposure aggravated low testosterone production in obese male mice accompanied by increased testicular oxidative stress and histological damages. In total, 363 and 242 differentially expressed proteins (DEPs) were identified in the two comparison groups, Obese/Control and Obese-Hypoxia/Obese, respectively. Functional enrichment analysis demonstrated that several significant functional terms and pathways related to testosterone production were altered in the two comparison groups. These included cholesterol metabolism, steroid hormone biosynthesis, peroxisome proliferator-activated receptor (PPAR) signaling pathway, oxidative stress responses, as well as retinol metabolism. Finally, 10 representative DEPs were selected for parallel reaction monitoring verification. Among them, StAR, DHCR7, NSDHL, CYP51A1, FDPS, FDX1, CYP11A1, ALDH1A1, and GPX3 were confirmed to be downregulated in the two groups.

CONCLUSIONS

Chronic hypoxia exposure could exacerbate low testosterone production in obese male mice by influencing the expression of key proteins involved in steroid hormone biosynthesis, cholesterol biosynthesis, oxidative stress responses and retinol metabolism.

Genetic spectrum and clinical characteristics of 3β-hydroxy-Δ5-C27-steroid oxidoreductase (HSD3B7) deficiency in China

BACKGROUND

Biallelic variants in HSD3B7 cause 3β-hydroxy-Δ5-C27-steroid oxidoreductase (HSD3B7) deficiency, a life-threatening but treatable liver disease. The goal of this study was to obtain detailed information on the correlation between the genotype and phenotype of HSD3B7 deficiency and to report on responses to primary bile acid therapy.

METHODS

The medical records of a cohort of 39 unrelated patients with genetically and biochemically confirmed HSD3B7 deficiency were examined to determine whether there exist genotype-phenotype relationships in this bile acid synthesis disorder.

RESULTS

In all, 34 of the 44 variants identified in HSD3B7 were novel. A total of 32 patients presented early with neonatal cholestasis, and 7 presented after 1-year of age with liver failure (n = 1), liver cirrhosis (n = 3), cholestasis (n = 1), renal cysts and abnormal liver biochemistries (n = 1), and coagulopathy from vitamin K1 deficiency and abnormal liver biochemistries (n = 1). Renal lesions, including renal cysts, renal stones, calcium deposition and renal enlargement were observed in 10 of 35 patients. Thirty-three patients were treated with oral chenodeoxycholic acid (CDCA) resulting in normalization of liver biochemistries in 24, while 2 showed a significant clinical improvement, and 7 underwent liver transplantation or died. Remarkably, renal lesions in 6 patients resolved after CDCA treatment, or liver transplantation. There were no significant correlations between genotype and clinical outcomes.

CONCLUSIONS

In what is the largest cohort of patients with HSD3B7 deficiency thus far studied, renal lesions were a notable clinical feature of HSD3B7 deficiency and these were resolved with suppression of atypical bile acids by oral CDCA administration.

[Infant with 3β-hydroxy-Δ(5)-C27 steroid dehydrogenase deficiency: report of two cases and literatures review]

OBJECTIVE

To study the clinical characteristics and early diagnosis of children with 3β-hydroxy-Δ(5)-C27-steroid dehydrogenase (3β-HSD) deficiency.

METHOD

Data related to clinical characteristics, serum biochemistry, liver pathology, gene mutations and treatment of two children with 3β-HSD deficiency were analyzed and relevant literature was reviewed. Fifty-three cases of 3β-HSD deficiency were reported since 1993 in the world.

RESULT

(1) Both patients showed neonatal cholestasis, blood biochemical examination of patient one showed alanine aminotransferase 292 U/L, aspartate aminotransferase 458 U/L, serum bile acids 1.8 µmol/L, total bilirubin 125.6 µmol/L, direct bilirubin 93.8 µmol/L, γ-glutamyl endopeptidase 43 U/L, bile biochemical test revealed bile acid 17.4 µmol/L, no itching; another patient showed alanine aminotransferase 812 U/L, aspartate aminotransferase 819 U/L, serum bile acids 4.9 µmol/L, total bilirubin 151.3 µmol/L, direct bilirubin 108.8 µmol/L, γ-glutamyl endopeptidase 50 U/L, bile biochemical test revealed bile acid 66.0 µmol/L, there was no itching. Both patients were confirmed by HSD3B7 gene mutation analysis. One patient had a homozygous mutation: 130_131insA, a novel mutation had not been reported, the other had compound heterozygous mutations: 544insG and 790C>C/A; The electron microscopic findings included bile pigment granules, fat droplets deposited in the cytoplasm of hepatocytes, glycogen granules increased, bile ductular dilatation or proliferation, bile plugs in canaliculus, biliary epithelial microvilli reduced, chronic inflammatory cell infiltration; (2) 53 cases were diagnosed by urine gas chromatography mass spectrometry (GC/MS) or fast atom bombardment mass spectrometry (FAB-MS), while 33 cases were diagnosed by HSD3B7 gene mutation analysis. All the patients had cholestatic jaundice, 22 cases of hepatomegaly, fats and fat-soluble vitamin malabsorption in 14 cases, blood γ-GT normal or decreased in 53 cases, normal or decreased serum bile acid in 53 cases, 49 cases had no skin itching. Two children were not treated before the age of 5, 1 child before the age of 13 were not treated in time, progressed to cirrhosis.

CONCLUSION

3β-hydroxy-Δ(5)-C27-steroid dehydrogenase is the most common bile acid synthetic defects described to date. The clinical presentation of this disorder include neonatal cholestasis, low or normal serum total bile acid concentration and a normal serum γ-GT concentration, bile acid significantly reduced in the bile. Definitive diagnosis can be achieved by gene analysis; Prompt diagnosis and early treatment are essential, primary bile acid treatment leads to clinical and biochemical control and prevents chronic liver disease.

Assisted reproduction technologies alter steroid delivery to the mouse fetus during pregnancy

Assisted reproduction technologies (ART) include in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI), and are common treatments for infertility. Although generally successful, ART warrant further investigations due to emerging perinatal issues, especially low birth weight. Herein we extend our previous work demonstrating higher steroid clearance in murine ART placentas by examining steroid biosynthesis and the directional flow of steroids in the maternal-placental-fetal units. The activities of the major steroidogenic enzymes 3β-hydroxysteroid dehydrogenase (3β-HSD) and cytochrome P450 17-αhydroxylase (CYP17) were assessed in maternal liver and ovaries and fetal livers as were levels of cholesterol, progesterone, estrone (E1), and estradiol (E2) in the maternal, placental and fetal units. No structural abnormalities were found in placentas from ART. Although ART increased 3β-HSD activity in maternal livers, there were no other changes in 3β-HSD- or CYP17-mediated steroidogenesis. Cholesterol levels were significantly lower in maternal livers of ICSI pregnancies and in placentas from both IVF and ICSI pregnancies but not altered in the fetal livers. Progesterone levels were higher in maternal and fetal livers in IVF and ICSI, respectively, but were significantly lowered in ICSI placentas, compared to normal fertilization. For estrogenic hormones, no differences in E1 or E2 levels were observed in maternal livers but ICSI significantly increased both E1 and E2 levels in placentas while both IVF and ICSI significantly lowered E1 but raised E2 levels in fetal livers. In summary, while steroid production was normal, steroid diffusion/flow from mother to fetus was altered in murine pregnancies conceived by ART. This appears to occur, at least in part; through placental mechanisms. Impaired cholesterol and steroid transfer may affect correct regulation of fetal growth and development.

KLF15 Is a transcriptional regulator of the human 17beta-hydroxysteroid dehydrogenase type 5 gene. A potential link between regulation of testosterone production and fat stores in women

CONTEXT

Kruppel-like factor 15 (KLF15) is a newly discovered transcription factor that plays an important role in glucose homeostasis and lipid accumulation in cells. We present evidence for KLF15 as a transcriptional regulator of the human 17beta-hydroxysteroid dehydrogenase type 5 gene (HSD17B5) and its potential role in the pathogenesis of hyperandrogenism.

OBJECTIVE

The aim was to investigate the molecular mechanism of HSD17B5 regulation.

METHODS

Diverse molecular biology techniques were used.

DESIGN AND RESULTS

We identified a KLF15 binding site in the HSD17B5 promoter by using luciferase promoter constructs, EMSA, and chromatin immunoprecipitation assays. Overexpression of KLF15 increased HSD17B5 promoter activity and testosterone formation at least 3-fold in cultured H295R cells. Insulin increased KLF15 mRNA expression according to real-time RT-PCR and increased HSD17B5 promoter activity according to luciferase assays. KLF15 overexpression in combination with insulin, glucocorticoid, and cAMP stimulated adipogenesis in H295R cells. In silico and RT-PCR analyses showed that the KLF15 gene promoter undergoes alternative splicing in a tissue-specific manner. Comparison of the HSD17B5 promoter in seven different species revealed that the KLF15 binding site has no human homolog in species other than orangutans.

CONCLUSIONS

KLF15 is potentially a novel link between the regulation of testosterone production and fat stores by insulin in humans.

Estrogen biosynthesis in human H295 adrenocortical carcinoma cells

Adrenocortical carcinoma is an uncommon malignancy and feminizing symptoms secondary to adrenal estrogen-secretion are extremely rare. The direct secretion of estradiol by adrenocortical tumors requires, in addition to the expression of aromatase (CYP19), the expression of one or more of the reductive 17beta-hydroxysteroid dehydrogenases. The expression of CYP19 transcripts and protein were markedly induced in the H295 adrenocortical carcinoma cell line after treatment with either forskolin or vasoactive intestinal peptide (VIP). Western immunoblotting demonstrated a marked induction of the CYP19 protein of characteristic size after only a short (6h) treatment period with VIP or forskolin. The CYP19 mRNA transcripts were derived from both promoters PII (Ic) and I.3 (Id) after treatment with both agents. The reductive type 5 17beta-hydroxysteroid dehydrogenase (AKR1C3) was also constitutively expressed in the H295 cells but neither its mRNA transcript nor protein levels were altered after forskolin or VIP treatment. Western immunoblotting of an estrogen-secreting adrenal carcinoma revealed notable levels of both aromatase and AKR1C3 expression while an aldosterone-producing adrenal adenoma lacked aromatase expression and showed a reduced level of AKR1C3 expression. Immunohistochemistry of the carcinoma-bearing adrenal revealed localization of AKR1C3 not only in the tumor but also principally in the zona reticularis of the normal adrenal tissue. Adrenal aromatase and AKR1C3 expression therefore appear to be features of adrenocortical malignancies that are associated with biosynthesis of active estrogen.

Adrenal changes associated with adrenarche

The mechanisms causing the rise in adrenal androgen production during the course of adrenarche remain to be defined. However, the increase in steroid release is clearly associated with a series of intra-adrenal changes in the expression of steroidogenic enzymes needed for dehydroepiandrosterone (DHEA) and dehydroepiandrosterone sulfate (DHEAS) production, as well as an expansion of the adrenal zona reticularis (ZR). We and others have defined the adrenal expression pattern of key steroidogenic enzymes during adrenarche. As adrenarche proceeds, the expanding ZR expresses greater levels of cytochrome b5 (CYB5) and steroid sulfotransferase (SULT2A1) than the adjacent fasciculata. In contrast, the growing ZR is deficient in 3beta-hydroxysteroid dehydrogenase type 2 (HSD3B2). The resulting profile of steroidogenic enzymes lends itself to the production of adrenal androgens and appears to track the progression of adrenarche. This article reviews the intra-adrenal changes of the adrenal cortex associated with adrenarche.

Expression of 17beta-hydroxysteroid dehydrogenase type 2 and type 5 in breast cancer and adjacent non-malignant tissue: a correlation to clinicopathological parameters

Estrogens play an important role in the development and progression of breast cancer. 17beta-Hydroxysteroid dehydrogenase (17beta-HSD) type 2 and type 5 are involved in sex steroid metabolism. 17beta-HSD type 2 converts estradiol to estrone while 17beta-HSD type 5 converts androstenedione to testosterone. Using immunocytochemistry, we have studied the expression of 17beta-HSD type 2 and type 5 in 50 specimens of breast carcinoma and adjacent non-malignant tissues. The results were correlated with the estrogen receptor alpha (ERalpha) and beta (ERbeta), progesterone receptor A (PRA) and B (PRB), androgen receptor and CDC47 and with the tumor stage, tumor size, nodal status and menopausal status. 17beta-HSD type 2 was expressed in 20% and 17beta-HSD type 5 in 56% of breast cancer specimens. In adjacent normal tissues, both enzymes were highly expressed in almost all the patients. No significant association could be found between the expression of 17beta-HSD type 2 and 17beta-HSD type 5 and between the expression of each enzyme and the clinicopathological parameters studied. The decrease in 17beta-HSD type 2 and 17beta-HSD type 5 expressions in breast cancer may play a predominant role in the development and/or progression of the cancer by modifying the intratumoral levels of estrogens and androgens.

Nonreplication of the type 5 17beta-hydroxysteroid dehydrogenase gene association with polycystic ovary syndrome

CONTEXT

Increased androgen production is a primary feature of polycystic ovary syndrome (PCOS) and appears to be an inherited trait. The gene for the steroidogenic enzyme type 5 17beta hydroxysteroid dehydrogenase (HSD17B5) was implicated as a candidate for the hyperandrogenemia of PCOS by a previous study that demonstrated an association of a single nucleotide polymorphism (SNP) in the promoter of this gene with PCOS.

OBJECTIVE

The objective of the study was to replicate the previous report of association between the HSD17B5 gene and PCOS risk by genotyping the promoter SNP (as well as other SNPs in the region to provide improved coverage of the gene) in a large, well-characterized cohort suitable for replication study.

DESIGN

Women with and without PCOS were genotyped for five SNPs in HSD17B5. SNPs and haplotypes were determined and tested for association with PCOS risk and phenotypic markers of PCOS.

SETTING

Subjects were recruited from the reproductive endocrinology clinic at the University of Alabama at Birmingham; controls were recruited from the surrounding community. Genotyping took place at Cedars-Sinai Medical Center in Los Angeles.

PARTICIPANTS

Participants included 287 white women with PCOS and 187 white controls.

MAIN MEASUREMENTS

HSD17B5 genotype, PCOS risk, and testosterone levels were measured.

RESULTS

No SNP or haplotype was significantly associated with PCOS risk, testosterone, or any of the traits tested.

CONCLUSIONS

These data suggest that polymorphisms in the HSD17B5 gene are not associated with PCOS risk or elevated testosterone as previously reported.

Regulation of 17beta-hydroxysteroid dehydrogenase type 2, type 4 and type 5 by calcitriol, LXR agonist and 5alpha-dihydrotestosterone in human prostate cancer cells

Vitamin D seems to be involved in the control of prostate cancer cell growth. 17beta-Hydroxysteroid dehydrogenases type 2, type 4 and type 5 are enzymes which regulate intracellular concentration of active sex steroid hormones, which in turn, regulate the development, growth, and function of the prostate and play a role in the development and progression of prostate cancer. Using quantitative real-time PCR we find that calcitriol up-regulates HSD17B type 2, type 4 and type 5 in human prostate cancer LNCaP and PC3 cells but not in stromal cells. LXR agonist, TO-901317, suppresses the expression of HSD17B2 mRNA and inhibits calcitriol induced HSD17B2 expression. TO-901317 up-regulates the expression of HSD17B5 but not that of HSD17B4. 5alpha-Dihydrotestosterone up-regulates the expression of HSD17B2 and HSD17B4 but it significantly inhibits HSD17B5 expression by 70%. Calcitriol has no effect on DHT mediated expression of the three genes. The regulation of HSD17B2, HSD17B4 and HSD17B5 by ligands of LXR and VDR as well as AR in prostate cancer cells suggests a complex interaction of these signaling systems in the prostate.

Lack of association between common polymorphisms in the 17beta-hydroxysteroid dehydrogenase type V gene (HSD17B5) and precocious pubarche

BACKGROUND

17beta-Hydroxysteroid dehydrogenase (type V; HSD17B5) is a key enzyme involved in testosterone production in females. A single nucleotide polymorphism (SNP) in the promoter region of its gene was recently found to be associated with polycystic ovary syndrome (PCOS) and its related hyperandrogenaemia. Precocious pubarche (PP) is a clinical entity pointing to adrenal androgen excess from mid-childhood onward and is associated with ovarian androgen excess from puberty onward. It is therefore a strong risk factor for PCOS.

METHODS

To investigate associations between this promoter SNP along with three exonic SNPs (one non-synonymous and two synonymous) from the same gene, and PP, a case-control study was performed in 190 girls with PP (84 of which were also tested for functional ovarian hyperandrogenism) from Barcelona, Spain and 71 healthy controls. Clinical features and hormone concentrations relevant to hyperandrogenism were compared by HSD17B5 genotype and haplotype.

RESULTS

Neither HSD17B5 genotypes nor haplotype were associated with PP, or subsequent androgen excess in girls from Barcelona (all P>0.05).

CONCLUSIONS

HSD17B5 SNPs predicted to have functional effects do not appear to be a risk factor for PP in girls from Barcelona, despite these girls being at high risk of developing androgen excess in adulthood.

Epstein-Barr virus lytic infection induces retinoic acid-responsive genes through induction of a retinol-metabolizing enzyme, DHRS9

Lytic Epstein-Barr virus (EBV) replication occurs in differentiated, but not undifferentiated, epithelial cells. Retinoic acid (RA) induces epithelial cell differentiation. The conversion of retinol into its active form, retinoic acid, requires retinol dehydrogenase enzymes. Here we show that AGS gastric carcinoma cells containing the lytic form of EBV infection have enhanced expression of a gene (DHRS9) encoding an enzyme that mediates conversion of retinol into RA. DHRS9 expression is also increased following induction of lytic viral infection in EBV-positive Burkitt lymphoma cells. We demonstrate that the EBV immediate-early protein, BZLF1, activates the DHRS9 promoter through a direct DNA binding mechanism. Furthermore, BZLF1 expression in AGS cells is sufficient to activate DHRS9 gene expression and increases the ability of retinol to induce the RA-responsive gene, CYP26A1. Production of RA during the lytic form of EBV infection may enhance viral replication by promoting keratinocyte differentiation.

Structure-based inhibitor design for an enzyme that binds different steroids: a potent inhibitor for human type 5 17beta-hydroxysteroid dehydrogenase

Human type 5 17beta-hydroxysteroid dehydrogenase plays a crucial role in local androgen formation in prostate tissue. Several chemicals were synthesized and tested for their ability to inhibit this enzyme, and a series of estradiol derivatives bearing a lactone on the D-ring were found to inhibit its activity efficiently. The crystal structure of the type 5 enzyme in complex with NADP and such a novel inhibitor, EM1404, was determined to a resolution of 1.30 A. Significantly more hydrogen bonding and hydrophobic interactions were defined between EM1404 and the enzyme than in the substrate ternary complex. The lactone ring of EM1404 accounts for important interactions with the enzyme, whereas the amide group at the opposite end of the inhibitor contributes to the stability of three protein loops involved in the construction of the substrate binding site. EM1404 has a strong competitive inhibition, with a Ki of 6.9+/-1.4 nM, demonstrating 40 times higher affinity than that of the best inhibitor previously reported. This is observed despite the fact that the inhibitor occupies only part of the binding cavity. Attempts to soak the inhibitor into crystals of the binary complex with NADP were unsuccessful, yielding a structure with a polyethylene glycol fragment occupying the substrate binding site. The relative crystal packing is discussed. Combined studies of small molecule inhibitor synthesis, x-ray crystallography, enzyme inhibition, and molecular modeling make it possible to analyze the plasticity of the substrate binding site of the enzyme, which is essential for developing more potent and specific inhibitors for hormone-dependent cancer therapy.

In situ androgen production in human gastric carcinoma--androgen synthesizing and metabolizing enzymes

BACKGROUND

It is well known that the incidence of gastric carcinoma is lower in females than in males. Therefore, androgens have been proposed to play an important role in modifying the development of gastric carcinoma. 5Alpha-reductase (5alpha-reductase) types 1 and 2 and 17beta-hydroxysteroid dehydrogenase type 5 (17beta-HSD type 5) are considered important local regulators of androgen production in human androgen-responsive tissues and cancer.

MATERIALS AND METHODS

The immunoreactivities of these steroidogenic enzymes, as well as of the androgen receptor (AR), were evaluated in human gastric carcinoma obtained from endoscopic mucosal resection (EMR) (n = 117).

RESULTS

17beta-HSD type 5 immunoreactivity was detected in 99 cases (85%), 5alpha-reductase type 1 in 69 cases (59%), 5alpha-reductase type 2 in 57 cases (49%) and AR in 46 cases (39%).

CONCLUSION

These androgen-producing enzymes are expressed in human gastric carcinomas and are involved in the in situ production and possible regulation of androgenic activity in human gastric carcinoma.

A generalized numerical approach to rapid-equilibrium enzyme kinetics: application to 17beta-HSD

A generalized numerical treatment of rapid-equilibrium enzyme kinetics is presented. This new approach relies on automatic computer derivation of the underlying mathematical model (a system of simultaneous nonlinear algebraic equations) from a symbolic representation of the reaction mechanism (a system of biochemical equations) provided by the researcher. The method allows experimental biochemists to analyze initial-rate enzyme kinetic data without having to use any mathematical equations. An illustrative example is based on the inhibition kinetics of 17beta-hydroxysteroid dehydrogenase type 5 by a class of natural compounds. A computer implementation of the new method, a newly modified software package DYNAFIT [Kuzmic, P., 1996. Program DYNAFIT for the analysis of enzyme kinetic data: application to HIV proteinase. Anal. Biochem. 237, 260-273], is freely available to all academic researchers.

[The culture and identification of rat testis Leydig cell]

OBJECTIVE

To establish a primary culture method of rat testis Leydig cell.

METHODS

The primary rat Leydig cells were treated with or without 4 U/ml human chorionic gonadotropin (hCG), and testosterone in culture medium was detected by radioimmunoassay. The morphology and biological characteristics of Leydig cell were observed.

RESULTS

The culture cells were highly homogeneous, proliferative and had a high differentiation rate. The high purified Leydig cells were verified by their dynamic morphological changes and 3beta-hydroxysteroid dehydrogenase delta4-delta5 isomerase (3beta-HSD) histochemical staining. The testosterone secretion induced by hCG significantly increased (P < 0.05) 24 hours after inoculation than that induced without hCG in the control.

CONCLUSION

It suggests that the Leydig cell cultured in vitro may secrete high concentration of testosterone, and this study laid the basis of androgen replacement therapy for partial androgen deficiency in aging male.

Changes in gene expression associated with loss of function of the NSDHL sterol dehydrogenase in mouse embryonic fibroblasts

Seven human disorders of postsqualene cholesterol biosynthesis have been described. One of these, congenital hemidysplasia with ichthyosiform nevus and limb defects (CHILD) syndrome, results from mutations in the X-linked gene NADH sterol dehydrogenase-like (NSDHL) encoding a sterol dehydrogenase. A series of mutant alleles of the murine Nsdhl gene are carried by bare patches (Bpa) mice, with Bpa(1H) representing a null allele. Heterozygous Bpa(1H) females display skin and skeletal abnormalities in a distribution reflecting random X inactivation, whereas hemizygous male embryos die before embryonic day 10.5. To investigate the molecular basis of defects associated with perturbations in cholesterol biosynthesis, microarray analysis was performed comparing gene expression in embryonic fibroblasts expressing the Bpa(1H) allele versus wild-type (wt) cells. Labeled cDNAs from cells grown in normal serum or lipid-depleted serum (LDS) were hybridized to microarrays containing 22,000 mouse genes. Among 44 genes that showed higher expression in the Bpa(1H) versus wt cells grown in LDS, 11 function in cholesterol biosynthesis, 7 are involved in fatty acid synthesis, 3 (Srebp2, Insig1, and Orf11) encode sterol-regulatory proteins, and 2 (Ldlr and StarD4) are lipid transporters. Of the 21 remaining genes, 16 are known genes, some of which have been implicated previously in cholesterol homeostasis or lipid-mediated signaling, and 5 are uncharacterized cDNA clones.

Characterization of the basal promoter element of the human type 5 17beta-hydroxysteroid dehydrogenase gene

Testosterone biosynthesis from androstenedione is carried out by androgenic 17beta-hydroxysteroid dehydrogenase (17beta-HSD) activity. Of the androgenic 17beta-HSD isoenzymes, only type 5 (17beta-HSD5) is expressed ubiquitously, including the human adrenal gland and ovary. To characterize this gene promoter, luciferase constructs of the human 5'-flanking region were transiently transfected into the H295R human adrenal carcinoma cell line. A series of fragment deletion constructs and electrophoretic mobility shift assays suggested that a sequence of CCTCCTCCT at -65 to -58 bp is the core sequence and demonstrated Sp1/Sp3 binding to this CCT repeat. Forskolin stimulated the promoter activity of the HSD17B5 gene through this Sp1/Sp3 binding site. Mutation of this site resulted in a significant reduction of HSD17B5 promoter basal and forskolin-induced activity. Mithramycin A, which inhibits the binding of Sp1 and Sp3 to DNA, also remarkably decreased HSD17B5 mRNA expression in the H295R cell line. These results indicate that members of the Sp family of transcription factors play an important role in regulating constitutive and stimulated expression of the HSD17B5 gene in H295R cells.

Expression and activity of steroid aldoketoreductases 1C in omental adipose tissue are positive correlates of adiposity in women

We examined expression and activity of steroid aldoketoreductase (AKR) 1C enzymes in adipose tissue in women. AKR1C1 (20alpha-hydroxysteroid dehydrogenase; 20alpha-HSD), AKR1C2 (3alpha-HSD-3), and AKR1C3 (17beta-HSD-5) are involved mainly in conversion of progesterone to 20alpha-hydroxyprogesterone and inactivation of dihydrotestosterone to 5alpha-androstane-3alpha,17beta-diol. Abdominal subcutaneous and omental adipose tissue biopsies were obtained during abdominal hysterectomies in seven women with low visceral adipose tissue (VAT) area and seven age- and total body fat mass-matched women with visceral obesity. Women with elevated VAT areas were characterized by significantly higher omental adipose tissue 20alpha-HSD and 3alpha-HSD-3 mRNA abundance compared with women with low VAT accumulations (1.4- and 1.6-fold differences, respectively; P < 0.05). Omental and subcutaneous adipose tissue 3alpha-HSD activities were significantly higher in women with high vs. low VAT areas (P < 0.05 for both comparisons). Total and visceral adiposities were positively associated with omental 20alpha-HSD mRNA level (r = 0.75, P < 0.003 for fat mass; r = 0.57, P < 0.04 for VAT area) and omental 3alpha-HSD-3 mRNA level (r = 0.68, P < 0.01 for fat mass; r = 0.74, P < 0.003 for VAT area). Enzyme activities in both depots were also positively correlated with adiposity measures. Omental adipose tissue enzyme expression and activity were positively associated with omental adipocyte size and LPL activity. In conclusion, mRNA abundance and activity of AKR1C enzymes in abdominal adipose tissue compartments are positive correlates of adiposity in women. Increased progesterone and/or dihydrotestosterone reduction in abdominal adipose tissue may impact locally on fat cell metabolism.

Characterization of a monoclonal antibody for human aldo-keto reductase AKR1C3 (type 2 3alpha-hydroxysteroid dehydrogenase/type 5 17beta-hydroxysteroid dehydrogenase); immunohistochemical detection in breast and prostate

Human aldo-keto reductase AKR1C3 (type 2 3alpha-hydroxysteroid dehydrogenase/type 5 17beta-hydroxysteroid dehydrogenase) catalyzes the reduction of Delta(4)-androstene-3,17-dione to yield testosterone, the reduction of 5alpha-dihydrotestosterone to yield 3alpha- and 3beta-androstanediol, and the reduction of estrone to yield 17beta-estradiol. Relatively, high mRNA expression of AKR1C3 was found in human prostate and mammary gland where it is implicated in regulating ligand access to the androgen and estrogen receptor, respectively. AKR1C3 shares high sequence identity >86% with related plastic human 20alpha-hydroxysteroid dehydrogenases (AKR1C1), type 3 3alpha-hydroxysteroid dehydrogenase (AKR1C2) and type 1 3alpha-hydroxysteroid dehydrogenase (AKR1C4), and reagents are urgently needed to discriminate between these enzymes at the mRNA, protein and functional level. We describe the characterization of a high-titer isoform specific monoclonal antibody (Ab) for AKR1C3. It does not cross react with human AKR1C1, AKR1C2 or AKR1C4, human aldehyde reductase AKR1A1 or rat 3alpha-hydroxysteroid dehydrogenase (AKR1C9) on immunoblot analysis. The monoclonal Ab can be used to detect AKR1C3 expression by immunohistochemistry in sections of paraffin-embedded mammary gland and prostate. In the breast enzyme staining was detected in ductal carcinoma in situ where the cancerous cells were strongly immunoreactive. In normal prostate immunoreactivity was limited to stromal cells with only faint staining in the epithelial cells. In adenocarcinoma of the prostate elevated staining was observed in the endothelial cells and carcinoma cells. The reagent thus has utility to access the localized expression of AKR1C3 in hormonal dependent malignancies of the breast and prostate.

Crystal structure of human prostaglandin F synthase (AKR1C3)

Prostaglandin H(2) (PGH(2)) formed from arachidonic acid is an unstable intermediate and is efficiently converted into more stable arachidonate metabolites (PGD(2), PGE(2), and PGF(2)) by the action of three groups of enzymes. Prostaglandin F synthase (PGFS) was first purified from bovine lung and catalyzes the formation of 9 alpha,11 beta-PGF(2) from PGD(2) and PGF(2)(alpha) from PGH(2) in the presence of NADPH. Human PGFS is 3 alpha-hydroxysteroid dehydrogenase (3 alpha-HSD) type II and has PGFS activity and 3 alpha-HSD activity. Human lung PGFS has been crystallized with the cofactor NADP(+) and the substrate PGD(2), and with the cofactor NADPH and the inhibitor rutin. These complex structures have been determined at 1.69 A resolution. PGFS has an (alpha/beta)(8) barrel structure. The cofactor and substrate or inhibitor bind in a cavity at the C-terminal end of the barrel. The cofactor binds deeply in the cavity and has extensive interactions with PGFS through hydrogen bonds, whereas the substrate (PGD(2)) is located above the bound cofactor and has little interaction with PGFS. Despite being largely structurally different from PGD(2), rutin is located at the same site of PGD(2), and its catechol and rhamnose moieties are involved in hydrogen bonds with PGFS. The catalytic site of PGFS contains the conserved Y55 and H117 residues. The carbonyl O(11) of PGD(2) and the hydroxyl O(13) of rutin are involved in hydrogen bonds with Y55 and H117. The cyclopentane ring of PGD(2) and the phenyl ring of rutin face the re-side of the nicotinamide ring of the cofactor. On the basis of the catalytic geometry, a direct hydride transfer from NADPH to PGD(2) would be a reasonable catalytic mechanism. The hydride transfer is facilitated by protonation of carbonyl O(11) of PGD(2) from either H117 (at low pH) or Y55 (at high pH). Since the substrate binding cavity of PGFS is relatively large in comparison with those of AKR1C1 and AKR1C2, PGFS (AKR1C3) could catalyze the reduction and/or oxidation reactions of various compounds over a relatively wide pH range.

Expression of progesterone metabolizing enzyme genes (AKR1C1, AKR1C2, AKR1C3, SRD5A1, SRD5A2) is altered in human breast carcinoma

BACKGROUND

Recent evidence suggests that progesterone metabolites play important roles in regulating breast cancer. Previous studies have shown that tumorous tissues have higher 5alpha-reductase (5alphaR) and lower 3alpha-hydroxysteroid oxidoreductase (3alpha-HSO) and 20alpha-HSO activities. The resulting higher levels of 5alpha-reduced progesterone metabolites such as 5alpha-pregnane-3,20-dione (5alphaP) in tumorous tissue promote cell proliferation and detachment, whereas the 4-pregnene metabolites, 4-pregnen-3alpha-ol-20-one (3alphaHP) and 4-pregnen-20alpha-ol-3-one (20alphaDHP), more prominent in normal tissue, have the opposite (anti-cancer-like) effects. The aim of this study was to determine if the differences in enzyme activities between tumorous and nontumorous breast tissues are associated with differences in progesterone metabolizing enzyme gene expression.

METHODS

Semi-quantitative RT-PCR was used to compare relative expression (as a ratio of 18S rRNA) of 5alphaR type 1 (SRD5A1), 5alphaR type 2 (SRD5A2), 3alpha-HSO type 2 (AKR1C3), 3alpha-HSO type 3 (AKR1C2) and 20alpha-HSO (AKR1C1) mRNAs in paired (tumorous and nontumorous) breast tissues from 11 patients, and unpaired tumor tissues from 17 patients and normal tissues from 10 reduction mammoplasty samples.

RESULTS

Expression of 5alphaR1 and 5alphaR2 in 11/11 patients was higher (mean of 4.9- and 3.5-fold, respectively; p < 0.001) in the tumor as compared to the paired normal tissues. Conversely, expression of 3alpha-HSO2, 3alpha-HSO3 and 20alpha-HSO was higher (2.8-, 3.9- and 4.4-fold, respectively; p < 0.001) in normal than in tumor sample. The mean tumor:normal expression ratios for 5alphaR1 and 5alphaR2 were about 35-85-fold higher than the tumor:normal expression ratios for the HSOs. Similarly, in the unmatched samples, the tumor:normal ratios for 5alphaR were significantly higher than the ratios for the HSOs.

CONCLUSIONS

The study shows changes in progesterone metabolizing enzyme gene expression in human breast carcinoma. Expression of SRD5A1 (5alphaR1) and SRD5A2 (5alphaR2) is elevated, and expression of AKR1C1 (20alpha-HSO), AKR1C2 (3alpha-HSO3) and AKR1C3 (3alpha-HSO2) is reduced in tumorous as compared to normal breast tissue. The changes in progesterone metabolizing enzyme expression levels help to explain the increases in mitogen/metastasis inducing 5alphaP and decreases in mitogen/metastasis inhibiting 3alphaHP progesterone metabolites found in breast tumor tissues. Understanding what causes these changes in expression could help in designing protocols to prevent or reverse the changes in progesterone metabolism associated with breast cancer.

The tumor suppressor adenomatous polyposis coli and caudal related homeodomain protein regulate expression of retinol dehydrogenase L

Development of normal colon epithelial cells proceeds through a systematic differentiation of cells that emerge from stem cells within the base of colon crypts. Genetic mutations in the adenomatous polyposis coli (APC) gene are thought to cause colon adenoma and carcinoma formation by enhancing colonocyte proliferation and impairing differentiation. We currently have a limited understanding of the cellular mechanisms that promote colonocyte differentiation. Herein, we present evidence supporting a lack of retinoic acid biosynthesis as a mechanism contributing to the development of colon adenomas and carcinomas. Microarray and reverse transcriptase-PCR analyses revealed reduced expression of two retinoid biosynthesis genes: retinol dehydrogenase 5 (RDH5) and retinol dehydrogenase L (RDHL) in colon adenomas and carcinomas as compared with normal colon. Consistent with the adenoma and carcinomas samples, seven colon carcinoma cell lines also lacked expression of RDH5 and RDHL. Assessment of RDH enzymatic activity within these seven cell lines showed poor conversion of retinol into retinoic acid when compared with normal cells such as normal human mammary epithelial cells. Reintroduction of wild type APC into an APC-deficient colon carcinoma cell line (HT29) resulted in increased expression of RDHL without affecting RDH5. APC-mediated induction of RDHL was paralleled by increased production of retinoic acid. Investigations into the mechanism responsible for APC induction of RDHL indicated that beta-catenin fails to repress RDHL. The colon-specific transcription factor CDX2, however, activated an RDHL promoter construct and induced endogenous RDHL. Finally, the induction of RDHL by APC appears dependent on the presence of CDX2. We propose a novel role for APC and CDX2 in controlling retinoic acid biosynthesis and in promoting a retinoid-induced program of colonocyte differentiation.

Crystal structures of the multispecific 17beta-hydroxysteroid dehydrogenase type 5: critical androgen regulation in human peripheral tissues

Human type 5 17beta-hydroxysteroid dehydrogenase (17beta-HSD5;AKR1C3) plays a major role in the metabolism of androgens in peripheral tissues. In prostate basal cells, this enzyme is involved in the transformation of dehydroepiandrosterone into dihydrotestosterone, the most potent androgen. It is thus a potential target for prostate cancer therapy because it is understood that the testosterone formation by this enzyme is an important factor, particularly in patients who have undergone surgical or medical castration. Here we report the first structure of a human type 5 17beta-HSD in two ternary complexes, in which we found that the androstenedione molecule has a different binding position from that of testosterone. The two testosterone-binding orientations in the substrate-binding site demonstrate the structural basis of the alternative binding and multispecificity of the enzyme. Phe306 and Trp227 are the key residues involved in ligand recognition as well as product release. A safety belt in the cofactor-binding site enhances nicotinamide adenine dinucleotide phosphate binding and accounts for its high affinity as demonstrated by kinetic studies. These structures have provided a dynamic view of the enzyme reaction converting androstenedione to testosterone as well as valuable information for the development of potent enzyme inhibitors.

The transcriptional regulating protein of 132 kDa (TReP-132) differentially influences steroidogenic pathways in human adrenal NCI-H295 cells

Steroid hormones synthesized from cholesterol in the adrenal gland are important regulators of many physiological processes. It is now well documented that the expression of many genes required for steroid biosynthesis is dependent on the coordinated expression of the nuclear receptor steroidogenic factor-1 (SF-1). However, transcriptional mechanisms underlying the species-specific, developmentally programmed and hormone-dependent modulation of the adrenal steroid pathways remain to be elucidated. Recently, we demonstrated that the transcriptional regulating protein of 132 kDa (TReP-132) acts as a coactivator of SF-1 to regulate human P450scc gene transcription in human adrenal NCI-H295 cells. The present study shows that overexpression of TReP-132 increases the level of active steroids produced in NCI-H295 cells. The conversion of pregnenolone to downstream steroids following TReP-132 expression showed increased levels of glucocorticoids, C(19) steroids and estrogens. Correlating with these data, TReP-132 increases P450c17 activities via the induction of transcript levels and promoter activity of the P450c17 gene, an effect that is enhanced in the presence of cAMP or SF-1. In addition, P450aro activity and mRNA levels are highly induced by TReP-132, whereas 3beta-hydroxysteroid dehydrogenase type II and P450c11aldo transcript levels are only slightly modulated. Taken together, these results demonstrate that TReP-132 is a trans-acting factor of genes involved in adrenal glucocorticoid, C(19) steroid and estrogen production.

Action of FGMgCO3Ap-collagen composite in promoting bone formation

To improve the biological properties of materials as bone substitutes, functionally graded CO3 apatite crystals containing magnesium, FGMgCO3Ap, were synthesized to be mixed with atelocollagen and made into a composite pellet. A radio-labeled cell adhesion experiment showed that the degree of adherence of mouse MC3T3E1 osteoblast-like cells to the FGMgCO3Ap-collagen composite was better than to CO3Ap-collagen and much better than to the Ti plate. When the composites were implanted beneath the periosteum cranii of rats, the FGMgCO3Ap-collagen composite was metabolized faster than the CO3Ap-collagen composite and better formation of new bone and osteoblast arrangement at the interface between the composite and the periosteum cranii was observed. When the composites were implanted into the femur of rabbits, clear bone formation with a higher degree of bone density was observed for the FGMgCO3Ap-collagen composite. These results suggest that the Mg2+ ions taken into the apatite crystals may contribute to the acceleration of osteoblast adhesion to apatites and promote bone formation, cross-talking with osteoblasts at the molecular level.

Left-sided CHILD syndrome caused by a nonsense mutation in the NSDHL gene

Congenital hemidysplasia with ichthyosiform nevus and limb defects (CHILD) syndrome is a rare X-linked dominant malformation syndrome characterized by unilaterally distributed ichthyosiform nevi, often sharply delimited at the midline, and ipsilateral limb defects. At least two-thirds of cases demonstrate involvement of the right side. Mutations in an essential enzyme of cholesterol biosynthesis, NAD(P)H steroid dehydrogenase-like [NSDHL], have been reported in five unrelated patients with right-sided CHILD syndrome and in a sixth patient with bilaterally, symmetric nevi and mild skeletal anomalies, but not with CHILD syndrome as originally defined. Although all of the molecularly diagnosed cases with the CHILD phenotype to date have had right-sided disease, we report here a novel nonsense mutation (E151X) of NSDHL in an infant with left-sided CHILD syndrome. This result demonstrates that both right- and left-sided CHILD syndrome can be caused by mutations in the same gene.

Localization of mammalian NAD(P)H steroid dehydrogenase-like protein on lipid droplets

Mammalian enzymes in late cholesterol biosynthesis have been localized uniformly over the endoplasmic reticulum by enzymatic methods. We report here the first mammalian cholesterol biosynthetic enzyme unequivocally localized at the surface of intracellular lipid storage droplets. NAD(P)H steroid dehydrogenase-like protein (Nsdhl), a mammalian C-3 sterol dehydrogenase involved in the conversion of lanosterol into cholesterol, was localized on lipid droplets by immunofluorescence microscopy and subcellular fractionation. Nsdhl was localized on lipid droplets even when cell growth exclusively depended on cholesterol biosynthesis mediated by this enzyme. Depletion of fatty acids in culture medium reduced the development of lipid droplets and caused Nsdhl redistribution to the endoplasmic reticulum. Elevating oleic acid in medium induced well developed, Nsdhl-positive lipid droplets, and simultaneously caused a reduction in cellular conversion of lanosterol into cholesterol. Manipulated human NSDHL with a missense mutation (G205S) causing a human embryonic developmental disorder, congenital hemidysplasia with ichthyosiform nevus and limb defects (CHILD) syndrome, could no longer be localized on lipid droplets. Although the expression of wild-type NSDHL could restore the defective growth of a CHO cholesterol auxotroph, LEX2 in cholesterol-deficient medium, the expression of NSDHL(G205S) failed to do so. These results point to functional significance of the localization of Nsdhl on lipid droplets. Functional significance was also suggested by the colocalization of Nsdhl on lipid droplets with TIP47, a cargo selection protein for mannose 6-phosphate receptors from late endosomes to the trans-Golgi network. These results add to the growing notion that the lipid droplet is an organelle endowed with more complex roles in various biological phenomena.

NSDHL, an enzyme involved in cholesterol biosynthesis, traffics through the Golgi and accumulates on ER membranes and on the surface of lipid droplets

NSDHL, for NAD(P)H steroid dehydrogenase-like, encodes a sterol dehydrogenase or decarboxylase involved in the sequential removal of two C-4 methyl groups in post-squalene cholesterol biosynthesis. Mutations in this gene are associated with human CHILD syndrome (congenital hemidysplasia with ichthyosiform nevus and limb defects), an X-linked, male lethal disorder, as well as the mouse mutations bare patches and striated. In the present study, we have investigated the subcellular localization of tagged proteins encoded by wild-type and selected mutant murine Nsdhl alleles using confocal microscopy. In addition to an ER localization commonly found for enzymes of post-squalene cholesterol biosynthesis, we have identified a novel association of NSDHL with lipid droplets, which are endoplasmic reticulum (ER)-derived cytoplasmic structures that contain a neutral lipid core. We further demonstrate that trafficking through the Golgi is necessary for ER membrane localization of the protein and propose a model for the association of NSDHL with lipid droplets. The dual localization of NSDHL within ER membranes and on the surface of lipid droplets may provide another mechanism for regulation of the levels and sites of accumulation of intracellular cholesterol.

Identification of two novel mutations in the murine Nsdhl sterol dehydrogenase gene and development of a functional complementation assay in yeast

Nsdhl is a 3beta-hydroxysterol dehydrogenase that is involved in the removal of C-4 methyl groups in the cholesterol biosynthetic pathway. Mutations in this gene are associated with the X-linked male lethal mouse mutations bare patches (Bpa) and striated (Str) and human CHILD syndrome. We have now detected the missense mutations V53D and A94T in conserved amino acids in two additional Bpa alleles. The latter alters the same amino acid as a missense mutation found in two unrelated CHILD patients, strongly suggesting that differences in the phenotype between Bpa mice and females with CHILD syndrome are unlikely to be explained by different types or sites of mutations. We have also demonstrated that the mouse NSDHL protein can rescue the lethality of erg26 deficient cells of Saccharomyces cerevisiae that lack the yeast ortholog, substantiating the role of NSDHL as a C-3 sterol dehydrogenase. Using this in vivo assay, we have demonstrated that two Str alleles function as hypomorphs, while three Bpa and one Str allele provide no complementation or rescue.

Human 17beta-hydroxysteroid dehydrogenase type 5 is inhibited by dietary flavonoids

Phytoestrogens contained in a vegetarian diet are supposed to have beneficial effects on the development and progression of a variety of endocrine-related cancers. We have tested the effect of a variety of dietary phytoestrogens, especially flavonoids, on the activity of human 17beta-hydroxysteroid dehydrogenase type 5 (17beta-HSD 5), a key enzyme in the metabolism of estrogens and androgens. Our studies show that reductive and oxidative activity of the enzyme are inhibited by many compounds, especially zearalenone, coumestrol, quercetin and biochanin A. Among flavones, inhibitor potency is enhanced with increased degree of hydroxylation. The most effective inhibitors seem to bind to the hydrophilic cofactor binding pocket of the enzyme.

Characterization of a novel airway epithelial cell-specific short chain alcohol dehydrogenase/reductase gene whose expression is up-regulated by retinoids and is involved in the metabolism of retinol

Multiple retinoic acid responsive cDNAs were isolated from a high density cDNA microarray membrane, which was developed from a cDNA library of human tracheobronchial epithelial cells. Five selected cDNA clones encoded the sequence of the same novel gene. The predicted open reading frame of the novel gene encoded a protein of 319 amino acids. The deduced amino acid sequence contains four motifs that are conserved in the short-chain alcohol dehydrogenase/reductase (SDR) family of proteins. The novel gene shows the greatest homology to a group of dehydrogenases that can oxidize retinol (retinol dehydrogenases). The mRNA of the novel gene was found in trachea, colon, tongue, and esophagus. In situ hybridization of airway tissue sections demonstrated epithelial cell-specific gene expression, especially in the ciliated cell type. Both all-trans-retinoic acid and 9-cis-retinoic acid were able to elevate the expression of the novel gene in primary human tracheobronchial epithelial cells in vitro. This elevation coincided with an enhanced retinol metabolism in these cultures. COS cells transfected with an expression construct of the novel gene were also elevated in the metabolism of retinol. The results suggested that the novel gene represents a new member of the SDR family that may play a critical role in retinol metabolism in airway epithelia as well as in other epithelia of colon, tongue, and esophagus.

Distribution of enzymes involved in the metabolism of glycyrrhizin in various organs of rat

Glycyrrhizin (GL) was hydrolyzed to glycyrrhetic acid (GA), glycyrrhetic acid mono-beta-D-glucuronide (GAMG) or both by glucuronidases in various organs of rat. GL beta-D-glucuronidase I, hydrolyzing GL to GA; GAMG beta-D-glucuronidase, hydrolyzing GAMG to GA; and 3alpha-hydroxyglycyrrhetinate (3alpha-hydroxyGA) dehydrogenase, oxidizing 3alpha-hydroxyGA to 3-oxo-GA were found in the organs of this animal. GL beta-D-glucuronidase II was distributed in the lysosomal fraction of all organs except brain; 3alpha-hydroxyGA dehydrogenase was distributed in the microsomal fraction of the liver; but other enzymes were distributed in the nuclear, lysosomal, microsomal and soluble fractions of a variety of organs. GL beta-D-glucuronidase I, GL beta-D-glucuronidase II and GAMG beta-D-glucuronidase activities in a mixture of lysosomes and microsomes of rat liver exhibited different patterns on hydroxyapatite column chromatography. These results showed the metabolic pathways of GL to be of two types: a beta-D-glucuronidase hydrolyzing GL to GA, and the other consisting of two different beta-D-glucuronidases hydrolyzing GL to GAMG and GAMG to GA.

3-BETA-HYDROXYSTEROID DEHYDROGENASE ACTIVITY IN THE HUMAN FOETAL TESTIS

Sections of testes from nine human foetuses ranging in crown-rump length from 3.0 to 18.3 cm were incubated to determine 3β-hydroxy-steroid dehydrogenase activity histochemically with the following steroids:

Pregnenolone and DHA gave a colour reaction in the interstitium of all testes studied. 17α-hydroxypregnenolone was utilised by testes from foetuses of C-R length 8.8 cm and over, androstenediol by testes from foetuses of C-R length 6.1 cm and over. These facts are thought to support the concept of separate substrate-specific 3β-hydroxysteroid dehydrogenases in the testis.

Pregnenolone sulphate was used by the interstitial cells of all testes studied but gave a stronger reaction than the free steroid. 17α-hydroxy-pregnenolone sulphate was used by all foetal testes surveyed. DHA sulphate was not well used by the interstitial cells. The utilisation of steroid sulphates in a different manner from the free steroids in this histochemical system may mean that the presence of a sulphate group affects enzyme-substrate binding or that a steroid sulphatase is involved.

Intense formazan deposition followed incubation with epiandrosterone in all testes studied. This seems to imply that a δ5 configuration is not necessary for enzyme-substrate binding.

Cytotoxic actions of cytokines on cultured mouse luteal cells are independent of nitric oxide

We investigated the cytotoxic effects of various cytokines secreted by macrophages or T lymphocytes on luteal cells, and the role of nitric oxide (NO) produced by luteal cells in cytotoxic actions of cytokines. Mouse luteal cells were cultured in serum-free medium with interferon-gamma (IFN-gamma), tumor necrosis factor-alpha (TNF-alpha) or interleukin-1 beta (IL-1 beta) alone, or with various combinations of these cytokines for 6 days. Cytotoxic actions of cytokines and NO production by luteal cells were evaluated by number of viable cells and the amount of nitrite and nitrate (stable metabolites of NO) in medium, respectively. IFN-gamma (1000 U/ml), TNF-alpha (3000 U/ml), or IL-1 beta (30 U/ml) alone, and the combination of TFN-alpha and IL-1 beta (10 U/ml) did not decrease number of viable cells and was without effects on NO production. The combination of IFN-gamma and IL-1 beta (10 U/ml) also did not decrease the number of viable cells, while it increased NO production a little but significantly. Combinations of INF-gamma and TNF-alpha, and IFN-gamma, TNF-alpha and IL-1 beta (10 U/ml) markedly decreased number of viable cells. The combination of IFN-gamma and TNF-alpha increased NO production a little but significantly, and the combination of three cytokines (IFN-gamma, TNF-alpha, and IL-1 beta) caused a greater increase in NO production. An NO synthase inhibitor, L-NG-monomethy-L-arginine (0.5 mM) or aminoguanidine (0.5 mM) abolished increases in NO production induced by combinations of IFN-gamma and TNF-alpha, and IFN-gamma, TNF-alpha and IL-1 beta completely without effects on number of viable cells. The present results indicate that combinations of cytokines including IFN-gamma and TNF-alpha induce death of cultured mouse luteal cells, and that the cytotoxic actions of these cytokines are independent of NO production by luteal cells.

Flow injection determination of glucose, bile acid and ATP using immobilized enzyme reactor and chemiluminescent assay of NAD(P)H

We have developed a chemiluminescent flow injection method for analysis of bile acid, glucose and ATP using the chemiluminescent assay of NADH using 1-methoxy-5-methylphenazinium methyl sulphate (1-MPMS)/isoluminol(IL)/microperoxidase (m-POD) system and immobilized enzyme reactors such as 3 alpha-hydroxysteroid dehydrogenase, glucose-dehydrogenase, hexokinase and glucose-6-phosphate dehydrogenase. The standard curves were obtained in the range of 5-100 pmol for bile acid, 0.5-5.0 nmol for glucose and 10(-7)-10(-5) mol/L for ATP. The coefficient of variation for each assay was not more than 4.1% for bile acid, 2.3% for glucose and 5.3% for ATP, respectively.

Determination of conjugated bile acids in human urine by high-performance liquid chromatography with chemiluminescence detection

A qualitative and quantitative analysis of the conjugated 1 beta- and 6 alpha-hydroxy bile acids, including common bile acids, in human urine using high-performance liquid chromatography with chemiluminescence detection is described. After extraction of urine with C18 silica cartridges, the bile acids were separated into non-conjugated, glycine, taurine and sulphate fractions by ion-exchange chromatography on a lipophilic gel. Solvolysis of the sulphate was carried out by treatment with trifluoroethanol in acetone containing hydrochloric acid, and the liberated amino acid conjugates were fractionated again. The individual bile acids were separated on a reversed-phase C18 column (Bile Pak II), with detection by an immobilized 3 alpha-hydroxysteroid dehydrogenase enzyme reactor and chemiluminescence reaction of the generated NADH using 1-methoxy-5-methylphenazinium methylsulphate-isoluminol-microperoxidase system. The assay method showed the detection limits ranging from 8 to 250 pmol for the bile acids tested. Analysis of urine samples obtained from newborns, non-pregnant women and women in late pregnancy showed a large difference in bile acid composition and conjugation mode, suggesting that bile acid metabolism is different during fetal and neonatal periods.

Metabolism of glycyrrhetic acid by rat liver microsomes--III. Male-specific glycyrrhetinate dehydrogenase

Glycyrrhetinate (GA) dehydrogenase localized in microsomes of rat liver catalyses the oxidation and reverse reduction of 18 beta-glycyrrhetic acid (GA), an aglycone of glycyrrhizin and a main component of liquorice, to 3-keto-18 beta-glycyrrhetic acid (3-ketoGA). The enzyme activity was detected in microsomes of adult males, but not in those of adult females. It was not observed in infant males but appeared 6 weeks after birth, increased gradually and reached the maximum level at 12 weeks after birth, whereas it was not detected in the hepatic microsomes of females of any age. The administration of estradiol valerate to intact adult males decreased GA dehydrogenase activity remarkably. Castration of male rats also caused a marked reduction of the activity, but the administration of testosterone proprionate to these rats restored it to close to the normal level. On the other hand, ovariectomy of female rats did not bring the activity into existence, but the injection of testosterone proprionate to the ovariectomized rats brought it into a slight existence, in spite of no appearance of the activity by the treatment of testosterone proprionate to intact adult females. The sex-related difference in the activity in adults was eliminated by hypophysectomy of male and female rats, their microsomal activities after the operation being the same, 20-40% of the activity in intact males. Moreover, the administration of estradiol valerate to the hypophysectomized rats did not affect the activity. These results indicate that GA dehydrogenase is male-specific and regulated by sex-hormones through the pituitary.

Cloning, nucleotide sequence, and transcriptional analysis of the NAD(P)-dependent cholesterol dehydrogenase gene from a Nocardia sp. and its hyperexpression in Streptomyces spp

NAD(P)-dependent cholesterol dehydrogenases [NAD(P)-CDH], which allow easier quantification of cholesterol by means of directly measuring the A340 of NAD(P)H, are useful for clinical purposes. The amino acid sequences of the NH2 terminus and the fragments obtained by CNBr decomposition of the NAD(P)-CDH from a Nocardia sp. were determined for preparation of synthetic oligonucleotides as hybridization probes. A 4.4-kbp BamHI fragment hybridizing to these probes was cloned on pUC19 in Escherichia coli. The nucleotide sequence together with the determined amino acid sequences revealed that this enzyme consists of 364 amino acids (Mr, 39,792) and contains an NAD(P)-binding consensus sequence at its NH2-terminal portion. High-resolution S1 nuclease mapping suggested that in NAD(P)-CDH of both Nocardia and Streptomyces spp. transcription initiates at the adenine residue, which is the first position of the translational initiation triplet (AUG) of this protein. The S1 mapping experiments also showed that cholesterol-dependent regulation in the Nocardia sp. occurred at the level of transcription. In Streptomyces lividans containing the cloned fragment, however, this promoter was expressed constitutively. DNA manipulation of the cloned gene in E. coli, including the generation of a ribosome-binding sequence at an appropriate position by oligonucleotide-directed mutagenesis, led to production of this protein in a very large amount but in the enzymatically inactive form of inclusion bodies. On the other hand, a Streptomyces host-vector system was successfully used for producing 40 times as much enzymatically active NAD(P)-CDH as that produced by the original Nocardia sp.