Showing papers on "Hydroxysteroid dehydrogenase published in 1990"

Human 3β-Hydroxysteroid Dehydrogenase/ δ5→4Isomerase from Placenta: Expression in Nonsteroidogenic Cells of a Protein that Catalyzes the Dehydrogenation/Isomerization of C21 and C19 Steroids*

Abstract: The isolation, cloning, and expression of a cDNA insert complementary to mRNA encoding human 3β- hydroxysteroid dehydrogenase/δ5→4isomerase is reported. The insert contains an open reading frame encoding a protein of 372 amino acids, the initial 29 amino acids corresponding to the Nterminal sequence identified from the purified human placental microsomal enzyme. The cDNA was inserted into a modified pCMV vector and expressed in COS-1 monkey kidney tumor cells. The expressed protein was similar in size to human placental microsomal 3β-hydroxysteroid dehydrogenase/ Aδ5→4isomerase, as detected by immunoblot analysis, and catalyzed the conversion of 17α-hydroxypregnenolone to 17α-hydroxyprogesterone, pregnenolone to progesterone, and dehydroepiandro3- terone to androstenedione. Transfected COS cell homogenates, supplemented with NAD+, very efficiently oxidized 5α-androstan- 3β,17β-diol to 5α-dihydrotestosterone and, upon addition of NADH, reduced 5α-dihydrotestosterone to 5α-androstan- 3β,17β-diol. Thus, the ...

Regulation of 1lβ-Hydroxysteroid Dehydrogenase Activity in the Baboon Placenta by Estrogen*

Abstract: We have previously shown that the change in transuteroplacental cortisol (F)-cortisone (E) metabolism in vivo from preferential reduction (E to F) at midgestation to oxidation by term (F to E) does not occur in baboons in which the production or action of estrogen have been blocked. Moreover, because the administration of androstenedione (Δ4A) to baboons increased estradiol (E2) production at midgestation and induced a pattern of F-E metabolism similar to that at term, we suggested that estrogen regulates placental F-E interconversion. The present study was designed to ascertain whether estrogen regulates the activity of the placental 11β-hydroxysteroid dehydrogenase (11βHSD) enzyme catalyzing the oxidation of F to E. Placentas were obtained on day 100 (n = 10) and day 165 (n = 10) of gestation (term = day 184) from untreated baboons, on day 100 from animals (n = 7) treated with Δ4A between days 70-100 of gestation, and on day 165 from animals in which placental estrogen was decreased by fetectomy (n = 5)...

Progestin induction of 17β-hydroxysteroid dehydrogenase enzyme protein in the t-47D human breast-cancer cell line

Abstract: Steroid regulation of 17 beta-hydroxysteroid dehydrogenase (17-HSD) was studied in the T-47D human breast-cancer cell line, using a radioimmunoassay. In addition, 3 mRNA species (2.4, 1.4, and 0.9 kb) specific for the enzyme were shown to be present in these cells. All the synthetic progestins tested (ORG 2058, R5020, medroxyprogesterone acetate) significantly increased the immunoreactive enzyme protein concentration, while other types of steroids, such as testosterone, oestradiol and dexamethasone, were ineffective. The progestin-specific induction of 17-HSD was dose-related and was maximum in about 5 days. An antiprogestin, RU 486, when used in combination with synthetic progestins, blocked the progestin-induced increase of 17-HSD concentration very effectively. A good correlation was observed in the different experiments between the enzyme activity and the immunoreactive 17-HSD concentration. We conclude that progestins induce 17-HSD in T-47D cells and that the induction occurs via an increased accumulation of enzyme protein.

Demonstration of 3 alpha(17 beta)-hydroxysteroid dehydrogenase distinct from 3 alpha-hydroxysteroid dehydrogenase in hamster liver.

Abstract: NAD(+)-linked and NADP(+)-linked 3 alpha-hydroxysteroid dehydrogenases were purified to homogeneity from hamster liver cytosol. The two monomeric enzymes, although having similar molecular masses of 38,000, differed from each other in pI values, activation energy and heat stability. The two proteins also gave different fragmentation patterns by gel electrophoresis after digestion with protease. The NADP(+)-linked enzyme catalysed the oxidoreduction of various 3 alpha-hydroxysteroids, whereas the NAD(+)-linked enzyme oxidized the 3 alpha-hydroxy group of pregnanes and some bile acids, and the 17 beta-hydroxy group of testosterone and androstanes. The thermal stabilities of the 3 alpha- and 17 beta-hydroxysteroid dehydrogenase activities of the NAD(+)-linked enzyme were identical, and the two enzyme activities were inhibited by mixing 17 beta- and 3 alpha-hydroxysteroid substrates, respectively. Medroxyprogesterone acetate, hexoestrol and 3 beta-hydroxysteroids competitively inhibited 3 alpha- and 17 beta-hydroxysteroid dehydrogenase activities of the enzyme. These results show that hamster liver contains a 3 alpha(17 beta)-hydroxysteroid dehydrogenase structurally and functionally distinct from 3 alpha-hydroxysteroid dehydrogenase.

Distribution of Dimeric Dihydrodiol Dehydrogenase in Pig Tissues and its Role in Carbonyl Metabolism

Abstract: A cytosolic NADP+-dependent dihydrodiol dehydrogenase (EC 1.3.1.20), that oxidizes dihydrodiol derivatives of benzene and naphthalene to the corresponding catechols, has been thought to play an important role in metabolic detoxification of carcinogenic polycyclic aromatic hydrocarbons (Oesch, et al., 1984) and in bioactivation of naphthalene in rabbit eye (van Heyningen, 1976). Dihydrodiol dehydrogenase was first isolated from rat liver (Vogel, et al., 1980) and has been subsequently identified as 3α-hydroxysteroid dehydrogenase (Penning, et al., 1984). The enzyme is a monomer of Mr35,000 and shows dehydrogenase activity for xenobiotic alicyclic alcohols and carbonyl reductase activity, which indicate that it also functions in carbonyl metabolism. Similar monomeric dihydrodiol dehydrogenases with broad substrate specificity for xenobiotics have been purified from other mammalian livers, and have been reported to be identical with 17s-hydroxysteroid dehydrogenase in the guinea pig (Hara, et al., 1986a), mouse (Sawada, et al., 1988) and rabbit (Hara, et al., 1986b), 3α(17β)-hydroxysteroid dehydrogenases in the hamster (Ohmura, et al., 1990), 3(20)α-hydroxysteroid dehydrogenase in the monkey (Hara, et al., 1989a), and aldehyde reductase.

Hormonal Regulation of Estradiol 17β‐Hydroxysteroid Dehydrogenase Activity in the ZR‐75‐1 Human Breast Cancer Cell Line

Abstract: Estrogens are known to play a major role in mammary tumor growth.' Among the mechanisms regulating estradiol (E2) action in estrogen target tissue^,^-^ the activity of the nicotinamide adenine dinucleotide (NAD)-dependent enzyme 17P-hydroxysteroid dehydrogenase (17P-HSD) plays an important role, because it converts the most potent natural estrogen 17P-estradiol (E2) into estrone (El), a less active compound.6 Recent elucidation of the complete amino acid sequence of human placental 17P-HSD deduced from its corresponding cDNA should provide detailed information about the properties and regulation of this enzyme, which should help our understanding of the hormone dependency of breast cancer.I The present study investigates the hormonal regulation of estradiol 17P-HSD in an in vitro model of human breast cancer. ZR-75-1 cells were thus preincubated for 10 days with optimal concentrations of selected steroids in the presence or absence of insulin. Seventeen-p-HSD was measured in cells incubated for 4 hours in the presence of [3H]E2 (20 nM). Quantification of the metabolites was achieved after extraction, partition, and separation by thin-layer chromatography. FIGURE 1 shows that the synthetic estrogen ethinylestradiol (EE2) decreases the activity of 17P-HSD by approximately 20 and 45% in the absence and presence of insulin, respectively. The specificity of the effect of ethinylestradiol is supported by an almost complete reversal of the effect of the estrogen by the steroidal antiestrogen ICI 164384. Although the synthetic progestin R5020 present alone does not exert a significant influence on the enzymatic activity of 17P-HSD in ZR-75-1 cells, it prevents the inhibitory action of the estrogen ethinylestradiol. Androgens, on the other hand, cause a threefold increase in 17P-HSD activity through specific interaction with the androgen receptor, as indicated by inhibition of the effect of dihydrotestosterone by the pure antiandrogen hydroxyflutamide (FIG. 2). Although ZR-751 cells possess glucocorticoids receptors and glucocorticoid are known to inhibit cell proliferation, treatment for 10 days with dexamethasone has no effect on 17pHSD activity (FIG. 1). The present data demonstrate that the activity of 17p-HSD is under the control of estrogens and androgens in the human breast cell line ZR75-1. Such activity may have an important influence on the response of breast cancer to hormonal therapy.

Study on dihydrodiol dehydrogenase (I) molecular forms of the enzyme and the presence of a dihydrodiol specific enzyme in bovine liver cytosol.

Abstract: It has been known that benzo(a)pyrene and benzo(a)anthracene, typical carcinogenic polycyclic aromatic hydrocarbons, are metabolized in microsome to the corresponding dihydrodiols via epoxides (Yang, et al., 1976; Thakker, et al., 1982) and then converted to the ultimate carcinogens (Buening, et al., 1978). Dihydrodiol dehydrogenase is an enzyme which catalyzes the dehydrogenation of the dihydrodiols of benzo(a)pyrene and benzo(a)anthracene in the presence of NADP+ and forms o-quinone (Vogel, et al., 1980; Smithgall, et al., 1988). The addition of this enzyme to the Ames test significantly reduced the mutagenicity of benzo(a)pyrene, suggesting that this enzyme might detoxify the trans-dihydrodiols which were formed in situ by oxidizing them to the less reactive o-quinones (Glatt, et al., 1979). In addition, similar experiments showed that the purified enzyme reduced the mutagenicity of other polycyclic aromatic hydrocarbons (Smithgall, et al., 1986). On the basis of these facts, Penning and coworkers suggested that dihydrodiol/ 3α -hydroxysteroid dehydrogenase might play an important role in the detoxification of these carcinogenic polycyclic aromatic hydrocarbons in rat liver (Smithgall, et al., 1988). Recently, many dihydrodiol dehydrogenases were purified from various animals and tissues, and these enzymes were identified as 3α -hydroxysteroid dehydrogenase, 17β -hydroxysteroid dehydrogenase and aldehyde reductase from their substrate specificities and inhibitor sensitivities (Smithgall, et al., 1988; Sawada, et al., 1988; Terada, et al., 1990).

Direct effects of lithium chloride on testicular delta 5-3 beta and 17 beta-hydroxysteroid dehydrogenase activities in the rat--in vitro study.

Abstract: Testicular delta 5-3 beta- and 17 beta-hydroxysteroid dehydrogenase (delta 5-3 beta- and 17 beta-HSD) activities of rat are inhibited in vitro by a wide range of lithium concentration. The inhibitory effects of lithium are evident at a concentration of 2.5 mM which is easily achieved during the treatment of acute manic patients with lithium. This suggests that lithium exerts a direct inhibitory effect on testicular hydroxysteroid dehydrogenase activities.

Optimization of 7α-hydroxysteroid dehydrogenase production by Escherichia coli 080

Abstract: 7α-Hydroxysteroid dehydrogenase (EC 1.1.1.159) production by Escherichia coli strain 080 was highest when the organism was grown in brain heart infusion broth at pH 6.5 for 72–96 h with shaking at ...

INVOLVEMENT OF pH IN THE ENHANCEMENT OF 20β-HYDROXYSTEROID DEHYDROGENASE ACTIVITY IN ISOLATED GRANULOSA CELL LAYERS FROM OVARIAN FOLLICLES OF SALMONID FISHES

Abstract: 20,6’-Hydroxysteroid dehydrogenase (2073-HSD) is a major enzyme involved in the gonadotropin-induced production of maturation-inducing hormone of oocytes, l70:,20,6-dihydroxy-4-pregnen-3-one (l7a,20,6’-diOHprog), by salmonid ovarian follicles. The present study was conducted to determine the effects of extracellular pH on gonadotropin-induced activation of 20,6-HSD using in virro incubation of isolated granulosa cell layers of rainbow trout, Salmo gairdneri, and amago salmon, Oncorhynclius rhodurus, at the late vitellogenic and the early migratory nucleus stages. 20,8-HSD activity was deduced by measuring levels of l7o:,20[5’-diOHprog derived from exogenous precursor 170:-hydroxyprogesterone (170:-OHprog) at various pH (6.5—8.5). Activity of 20,6’-HSD at both stages was dramatically enhanced by the addition of chum salmon gonadotropin (SGA), forskolin, or dibutyryl cAMP (dbcAMP) at higher pH (27.5). In contrast, the activation was suppressed by more than 60% at pH 7.0, and almost 100% at pH 6.5. A lower pH did not, however, influence the enzymatic conversion of 170:-OHprog to l7a,20fl-diOHprog in granulosa cell layers in which 20,6’-HSD had already been activated by pretreatment with SGA at pH 7.5. Even without SGA, a higher pH (28.0) itself partially activated 20,6’-HSD at the early migratory nucleus stage. The higher pH-induced 20,6’-HSD activation was totally inhibited by cycloheximide, a protein synthesis inhibitor. Granulosa cell layers showed no SGA-, forskolin-, or dbcAMP-induced 20,6’-HSD activation in sodium-deficient media. Amiloride, a Na+/H+ exchanger inhibitor, also blocked 20,6-HSD activation in a dose-dependent manner. These results suggest that fluctuations of intracellular pH play an important role in gonadotropin-induced 20,6HSD activation in granulosa cell layers of salmonid ovarian follicles. Oocyte maturation in teleosts is regulated by production in salmonid ovarian follicles are a follicular steroidal mediator, maturationthe stimulation of 17a-hydroxyprogesterone inducing steroid (MIS), under the control of (I70:-OHprog) production by thecal cell layers gonadotropin (7, 18). l7ci,20,B-Dihydroxy-4and the enhancement of the activity of 205pregnen-3-one (l7a,20,8-diOHprog) wasidenhydroxysteroid dehydrogenase (2046-HSD), tified as the natural MIS in amago salmon the key enzyme involved in the conversion of (19) The major roles of gonadotropin in MIS 17a-OHprog to l7a,20,6’-diOHprog, in granu-