Showing papers on "Hydroxysteroid dehydrogenase published in 2007"

Carbonyl reductases and pluripotent hydroxysteroid dehydrogenases of the short-chain dehydrogenase/reductase superfamily.

Abstract: Carbonyl reduction of aldehydes, ketones, and quinones to their corresponding hydroxy derivatives plays an important role in the phase I metabolism of many endogenous (biogenic aldehydes, steroids, prostaglandins, reactive lipid peroxidation products) and xenobiotic (pharmacologic drugs, carcinogens, toxicants) compounds. Carbonyl-reducing enzymes are grouped into two large protein superfamilies: the aldo-keto reductases (AKR) and the short-chain dehydrogenases/reductases (SDR). Whereas aldehyde reductase and aldose reductase are AKRs, several forms of carbonyl reductase belong to the SDRs. In addition, there exist a variety of pluripotent hydroxysteroid dehydrogenases (HSDs) of both superfamilies that specifically catalyze the oxidoreduction at different positions of the steroid nucleus and also catalyze, rather nonspecifically, the reductive metabolism of a great number of nonsteroidal carbonyl compounds. The present review summarizes recent findings on carbonyl reductases and pluripotent HSDs of the SDR protein superfamily.

Adrenal 20α-Hydroxysteroid Dehydrogenase in the Mouse Catabolizes Progesterone and 11-Deoxycorticosterone and Is Restricted to the X-Zone

Abstract: The enzyme 20alpha-hydroxysteroid dehydrogenase (20alpha-HSD) is a progesterone-catabolizing enzyme that is highly expressed in mouse ovaries and adrenals. Although the functional significance of ovarian 20alpha-HSD for the induction of parturition has been defined, regulation and distribution of 20alpha-HSD in the adrenal gland has not been determined. We demonstrate that the expression of adrenal 20alpha-HSD is restricted to the X-zone, a transient zone between the adrenal cortex and the medulla of yet unknown function. Adrenal 20alpha-HSD activity in male mice peaks at 3 wk of age and disappears thereafter, whereas 20alpha-HSD enzyme activity is maintained in adrenals from nulliparous female animals. Testosterone treatment of female mice induces rapid involution of the X-zone that is associated with the disappearance of the 20alpha-HSD-positive cells. Conversely, reappearance of 20alpha-HSD expression and activity in male animals is evident after gonadectomy. Moreover, pregnancy, but not pseudopregnancy, is accompanied by X-zone regression and loss of 20alpha-HSD activity. Pregnancy-induced X-zone regression and -abolished 20alpha-HSD expression is partially restored in animals that were kept from nursing their pups. We found that in addition to its progesterone-reducing activity, 20alpha-HSD also functions as an 11-deoxycorticosterone-catabolizing enzyme. The unaltered growth kinetics of the X-zone in 20alpha-HSD knockout animals suggests that 20alpha-HSD is not required for the regulation of X-zone growth. However, 20alpha-HSD expression and enzymatic activity in all experimental paradigms is closely correlated with the presence of the X-zone. These findings provide the basis for 20alpha-HSD as a reliable marker of the murine X-zone.

Type 2 diabetes and metabolic syndrome are associated with increased expression of 11beta-hydroxysteroid dehydrogenase 1 in obese subjects.

Abstract: Type 2 diabetes and metabolic syndrome are associated with increased expression of 11 β -hydroxysteroid dehydrogenase 1 in obese subjects

Differential androgen and estrogen substrates specificity in the mouse and primates type 12 17β-hydroxysteroid dehydrogenase

Abstract: Recently, we have shown that human and monkey type 12 17b-hydroxysteroid dehydrogenases (17b-HSD12) are estrogen-specific enzymes catalyzing the transformation of estrone (E1) into estradiol (E2). To further characterize this novel steroidogenic enzyme in an animal model, we have isolated a cDNA fragment encoding mouse 17b-HSD12 and characterized its enzymatic activity. Using human embryonic kidney cells (HEK)-293 cells stably expressing mouse 17b-HSD12, we found that in contrast with the human and monkey enzymes, which are specific for the transformation of E1 to E2, mouse 17b-HSD12 also catalyzes the transformation of 4androstenedione into testosterone (T), dehydroepiandrosterone (DHEA) into 5-androstene-3b,17b-diol (5-diol), as well as androsterone into 5a-androstane-3a,17b-diol (3a-diol). Previously, we have shown that the specificity of human and monkey 17b-HSD12s for C18-steroid is due to the presence of a bulky phenylalanine (F) at position 234 creating steric hindrance, preventing the entrance of C19-steroids into the active site. To determine whether the smaller size of the corresponding leucine (L) in the mouse sequence is responsible for the entrance of androgenic substrates, we performed site-directed mutagenesis to substitute Leu 234 for Phe in the mouse enzyme. In agreement with our hypothesis, the mutated enzyme has a highly reduced ability to metabolize androgens. mRNA quantification in several mouse tissues using real-time PCR shows that mouse 17bHSD12 mRNA is highly expressed in the female clitoral gland, male preputial gland, as well as in retroperitoneal fat and adrenal of both sexes. The differential androgenic/estrogenic substrate specificity of type 12 17b-HSD in the mouse and primates seems to agree with the observation that androgen and estrogen in the mouse are provided almost exclusively by gonads, while in primates an important part of these steroid hormones are produced locally from adrenal precursors.

Regulation of 17-Beta Hydroxysteroid Dehydrogenase Type 2 in Human Placental Endothelial Cells

Abstract: 17-beta hydroxysteroid dehydrogenase type 2 (HSD17B2) oxidizes estradiol to estrone, testosterone to androstenedione, and 20 alpha-dihydroprogesterone to progesterone. HSD17B2 is highly expressed in human placental tissue where it is localized to placental endothelial cells lining the fetal compartment. The aim of this study was to investigate the effects of potential regulatory factors including progesterone, estradiol, and retinoic acid (RA) onHSD17B2 expression in primary human placental endothelial cells in culture.HSD17B2 mRNA expression was not regulated by progesterone, the progesterone agonist R5020, or estradiol treatment. RA significantly induced HSD17B2 mRNA levels and enzyme activity in a dose- and time-dependent manner. Maximal stimulation occurred at Hour 48 at an RA concentration of 10(-6) M. Both retinoic acid receptor alpha (RARA) and retinoid X receptor alpha (RXRA) were readily detected by immunoblotting in isolated placental endothelial cells. RNA interference directed against RARA or RXRA led to reduced basal levels of HSD17B2 mRNA levels and significantly abolished RA-stimulated HSD17B2 expression. Together, these data indicate that regulation of HSD17B2 mRNA levels and enzymatic activity by RA in the placenta is mediated by RARA and RXRA.

Expression and localization of estrogenic type 12 17β-hydroxysteroid dehydrogenase in the cynomolgus monkey

Abstract: Background We have recently discovered that human type 12 17β-HSD (h17β-HSD12), a homolog of type 3 17β-HSD, is a new estrogen-specific 17β-hydroxysteroid dehydrogenase involved in the production of estradiol (E2). To further characterize this estradiol-producing enzyme, we have isolated the corresponding cDNA in the cynomolgus monkey (Macaca fascicularis), characterized its enzymatic activities and performed cellular localization using in situ hybridization.

Suppression of male reproduction in rats after exposure to sodium fluoride during early stages of development

Abstract: Sodium fluoride (NaF), a widespread natural pollutant was given to sperm-positive female rats throughout gestation and lactation at a dose of 45 and 90 ppm via drinking water The neonates were allowed to grow up to 90 days on tap water, and then sperm parameters, testicular steroidogenic marker enzyme activity levels, and circulatory hormone levels were studied The sperm count, sperm motility, sperm coiling (hypoosmotic swelling test), and sperm viability were decreased in experimental rats when compared with controls The activity levels of testicular steroidogenic marker enzymes (3β hydroxysteroid dehydrogenase and 17β hydroxysteroid dehydrogenase) were significantly decreased in experimental animals indicating decreased steroidogenesis The serum testosterone, follicle stimulating hormone and luteinizing hormone levels were also significantly altered in experimental animals Our data indicate that exposure to NaF during gestation and lactation affects male reproduction in adult rats by decreasing spermatogenesis and steroidogenesis

Transgenic male mice expressing human hydroxysteroid dehydrogenase 2 indicate a role for the enzyme independent of its action on sex steroids.

Abstract: Hydroxysteroid (17beta) dehydrogenase 2 (HSD17B2) has been shown to inactivate both estrogens and androgens and activate 20alpha-hydroxyprogesterone to progesterone. In the present study, we generated transgenic (TG) mice ubiquitously expressing human HSD17B2. The TG mice produced showed growth retardation and delayed eye opening at the postnatal age. Disrupted spermatogenesis was evident in the presence of normal serum and intratesticular testosterone, progesterone, and normal circulating LH concentrations. A proper androgen action in the target tissues was confirmed by normal histological appearance of the prostate and epididymis. Furthermore, quantitative RT-PCR analysis indicated only a slight decrease in androgen-dependent gene expression in the prostate. The disrupted spermatogenesis was not associated with increased germ cell apoptosis as analyzed by caspase-3 activation. However, it resulted in infertility in the HSD17B2 TG males after the age of 3 months, and at the age of 6 months the seminiferous tubules showed a Sertoli cell-only phenotype. The data indicate that the growth retardation and disrupted spermatogenesis are not due to a lack of proper estrogen or androgen action. Interestingly, the testicular phenotype and some of the other phenotypic changes described are typically observed in mice with reduced action of retinoic acid signaling. This, together with the rescue of the testis phenotype by a synthetic retinoic acid receptor agonist (4-[(E)-2-(5, 6, 7, 8-tetrahydro-5, 5, 8, 8-tetramethyl-2-naphthalenyl)-1-propenyl] benzoic acid), suggests a role for HSD17B2 in the action of retinoids, in addition to its oxidative HSD17B activity on sex steroids.

Hydroxysteroid Dehydrogenase (17β -HSD3, 17β-HSD5, and 3α-HSD3) Inhibitors:Extragonadal Regulation of Intracellular Sex Steroid Hormone Levels

Abstract: Sex hormone signaling regulates the growth, differentiation and development of many tissues. The intracellular concentrations of sex hormones are regulated by several enzymes, including the 17β-hydroxysteroid dehydrogenases (17β-HSDs) and 3α- hydroxysteroid dehydrogenases (3α-HSDs). Most notably, these enzymes are involved in the oxidation and reduction of ketone and β- hydroxyl groups at the C17 position of androgens and estrogens. Fourteen mammalian 17β-HSDs have been identified to date; and are grouped into oxidative enzymes (17β-HSD types 2, 4, 6, 8, 9, 10, 11 and 14) that catalyze the NAD+-dependent inactivation of sex hormones and reductive enzymes (17β-HSD types 1, 3, 5 and 7) that catalyze the formation of more potent steroid receptor ligands. The proliferative effects of androgens and estrogens in target tissues and over-expression of 17β-HSDs in cancer have led to intense drug discovery efforts to identify and develop 17β-HSD inhibitors that can be used for the treatment of breast, prostate and endometrial cancers, neurological disorders, endometriosis, acne, hirsutism and other hormone dependent and independent diseases. Potent and selective inhibitors of intracellular androgen biosynthesis have been reported and, recent proof-of-concept data suggests that these agents have utility in the treatment of androgen-dependent diseases. This review summarizes recent patents and scientific literature regarding steroidal and nonsteroidal 17β-HSD3, 17β-HSD5, and 3α-HSD3 inhibitors and their promise for treatment of androgen-dependent diseases.

5-Androstane-3,7,17-triol and 5-androstane-3,7,17-triol as substrates for the human 11-hydroxysteroid dehydrogenase type 1

Abstract: Several studies have shown that the native 7-hydroxy-dehydroepiandrosterone (7hydroxy-DHEA) is a substrate for the human 11-hydroxysteroid dehydrogenase type 1 (11-HSD1) which converts the 7- into the 7-epimer through an oxido-reduction process. Research on the 11-HSD1 has investigated its function and structure through using native glucocorticoid substrates and known inhibitors. Other steroid substrates are also of interest. Among testosterone metabolites, 5-androstane-3,17-diol (Adiol) is a substrate for the cytochrome P450 7B1 which produces 5-androstane-3,7,17-triol (7-Adiol). This steroid may be a substrate for the 11-HSD1. We used recombinant yeast-expressed 11-HSD1 with NADP(H)-regenerating systems for examining the products obtained after incubation with 7-Adiol, 7-Adiol or 7-oxo-Adiol. Oxidative conditions for the 11-HSD1 provided no trace of 7-oxo-Adiol but the inter-conversion of 7- and 7-hydroxy-Adiol with Vmax/KM (pmol min −1 g −1 /M) values of 2 and 0.5, respectively. This state was maintained under reductive conditions. The use of a 7-oxo-Adiol substrate under reductive conditions led to the production of both 7- and 7-hydroxy-Adiol with Vmax/KM values of 3.43 and 0.22, respectively. These findings support the hypothesis that the oxido-reductase and epimerase activities of 11-HSD1 depend on the positioning of the steroid substrates within the active site and may provide insight into its fine structure and mechanism of action.

Gender Differences of Enzymatic Activity and Distribution of 17β-Hydroxysteroid Dehydrogenase in Human Skin in vitro

Abstract: The interconversion of estrone (E1) and 17β-estradiol (E2) is catalyzed by 17β-hydroxysteroid dehydrogenase (17β-HSD) in peripheral steroidogenic organs such as the skin. To inve

11-Beta hydroxysteroid dehydrogenase type 2 in human adult and fetal lung and its regulation by sex steroids.

Abstract: 11-Beta hydroxysteroid dehydrogenase type 2 (HSD2) oxidizes the biologically active glucocorticoid (GC), cortisol, to inactive cortisone We characterized HSD2 gene expression and activity in human adult and fetal lung tissues and in cultured fetal lung explants, and examined the potential regulation of HSD2 in the fetal lung by sex steroids Human adult lung, fetal lung, and cultured fetal lung explant tissues contained similar amounts of HSD2 mRNA However, higher levels of HSD2 protein were detected in human fetal lung tissue than in adult lung, with expression being restricted to a subset of epithelial cells in the fetal lung tissue Differentiated fetal lung explants maintained in culture expressed higher levels of HSD2 protein and enzymatic activity than undifferentiated fetal lung tissues Finally, HSD2 protein levels were decreased in male, but not female, fetal lung explants treated with 17-beta estradiol In contrast, 5-alpha dihydrotestosterone did not significantly affect HSD2 levels These data indicate that HSD2 protein and activity levels increase in parallel with the differentiation of alveolar type II epithelial cells in vitro, and that HSD2 protein levels are regulated by 17-beta estradiol in male fetal lung tissue

Process for the preparation of steroid derivatives by reduction of oxosteroid compounds or by oxidation of hydroxysteroid compounds using a hydroxysteroid dehydrogenase

Abstract: A process for the enantioselective enzymatic reduction of compounds which have a steroid structure (ABCD), including one or more heteroatoms, one or more double bonds and/or an aromatic in the ring structure and which have at least one oxo group at position 3, 7, 11, 12 or 17 of the steroid ring system or in α-position at any carbon radical on the steroid skeleton (= oxosteroid compound/hydroxysteroid compound), where the oxosteroid compound is reduced with a hydroxysteroid dehydrogenase in the presence of a cofactor NADH or NADPH is characterized in that a) the oxosteroid compound is present in the reaction mixture in a concentration of >50 g/l, b) the oxidized cofactor NAD or NADP which is formed by the hydroxysteroid dehydrogenase is regenerated continuously by oxidation of a secondary alcohol of the general formula RxRyCHOH where Rx, Ry independently of one another represent hydrogen, branched or unbranched Cl-C8-alkyl and Ctotal ≥3, or by oxidation of a C4-C6-cycloalkanol, and c) an additional oxidoreductase/alcohol dehydrogenase is employed for oxidizing the secondary alcohol of the general formula RXRYCHOH or of the cycloalkanol.

Structure of 3(17)alpha-hydroxysteroid dehydrogenase (AKR1C21) holoenzyme from an orthorhombic crystal form: an insight into the bifunctionality of the enzyme.

Abstract: Mouse 3(17)α-hydroxysteroid dehydrogenase (AKR1C21) is a bifunctional enzyme that catalyses the oxidoreduction of the 3- and 17-hydroxy/keto groups of steroid substrates such as oestrogens, androgens and neurosteroids. The structure of the AKR1C21–NADPH binary complex was determined from an orthorhombic crystal belonging to space group P212121 at a resolution of 1.8 A. In order to identify the factors responsible for the bifunctionality of AKR1C21, three steroid substrates including a 17-keto steroid, a 3-keto steroid and a 3α-hydroxysteroid were docked into the substrate-binding cavity. Models of the enzyme–coenzyme–substrate complexes suggest that Lys31, Gly225 and Gly226 are important for ligand recognition and orientation in the active site.