Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.1.1.3 (HSD)
 3,464 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The in vitro effects of dehydroepiandrosterone (DHA) and allylestrenol on human placental delta 5- 3 beta-hydroxysteroid dehydrogenase, delta 4,5 isomerase activity (delta 5-3 beta-HSDH) was investigated by incubation of subcellular fractions with [4-14C] pregnenolone. It has been found that DHA inhibits the delta 5-3 beta-HSDH activity up to -81% at 5 X 10-5 M concentration while allylestrenol seems to be able to lightly stimulate the delt a 5-3 beta-HSDH activity with a maximum effect (+15-26%) at 5 X 10-7 M concentration. The data concerning allylestrenol, seem of particular interest as this compound is used as a progestative drug during pregnancy, if one consider the inhibitory effect exerted by several natural and synthetic steroids on the delta 5-3 beta-HSDH activity.
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PMID:Human placental delta 5-3 beta-hydroxysteroid dehydrogenase, delta 4,5 isomerase: in vitro effect of dehydroepiandrosterone and allyestrenol. 15 6

Transient expression in nonsteroidogenic mammalian cells of the rat wild type I and type II 3 beta-hydroxysteroid dehydrogenase/delta 5-delta 4-isomerase (3 beta-HSD) cDNAs shows that the encoded proteins, in addition to being able to catalyze the oxidation and isomerization of delta 5-3 beta-hydroxysteroid precursors into the corresponding delta 4-3-ketosteroids, interconvert 5 alpha-dihydrotestosterone (DHT) and 5 alpha-androstane-3 beta,17 beta-diol (3 beta-diol). When homogenate from cells transfected with a plasmid vector containing type I 3 beta-HSD is incubated in the presence of DHT using NAD+ as cofactor, a somewhat unexpected metabolite is formed, namely 5 alpha-androstanedione (A-dione), thus indicating an intrinsic androgenic 17 beta-hydroxysteroid dehydrogenase (17 beta-HSD) activity of this 3 beta-HSD isoform. Although the relative Vmax of 17 beta-HSD activity is 14.9-fold lower than that of 3 beta-HSD activity, the Km value for the 17 beta-HSD activity of type I 3 beta-HSD is 7.97 microM, a value which is in the same range as the conversion of DHT into 3 beta-diol which shows a Km value of 4.02 microM. Interestingly, this 17 beta-HSD activity is highly predominant in unbroken cells in culture, thus supporting the physiological relevance of this "secondary" activity. Such 17 beta-HSD activity is inhibited by the classical substrates of 3 beta-HSD, namely pregnenolone (PREG), dehydroepiandrosterone (DHEA), delta 5-androstene-3 beta,17 beta-diol (delta 5-diol), 5 alpha-androstane-3 beta,17 beta-diol (3 beta-diol) and DHT, with IC50 values of 2.7, 1.0, 3.2, 6.2, and 6.3 microM, respectively. Although dual enzymatic activities have been previously reported for purified preparations of other steroidogenic enzymes, the present data demonstrate the multifunctional enzymatic activities associated with a recombinant oxidoreductase enzyme. In addition to its well known 3 beta-HSD activity, this enzyme possesses the ability to catalyze DHT into A-dione thus potentially controlling the level of the active androgen DHT in classical steroidogenic as well as peripheral intracrine tissues.
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PMID:Androgenic 17 beta-hydroxysteroid dehydrogenase activity of expressed rat type I 3 beta-hydroxysteroid dehydrogenase/delta 5-delta 4 isomerase. 130 51

We have previously demonstrated that cyclosporine inhibits testosterone (T) biosynthesis in vivo. To better understand the mechanism by which CsA inhibits T synthesis, interstitial cells were isolated from rat testes and incubated in the standard medium 199 with or without CsA (0-10 micrograms/ml) in the presence or absence of human chorionic gonadotropin (hCG, 10(-7) M) and 8-bromo cyclic AMP (cAMP, 0.5 mM) for 3 hr at 32 degrees C. The levels of cAMP and T were determined by RIA. CsA did not inhibit the basal secretion of T, but inhibited hCG-stimulated T production in a dose-dependent manner (4 ng/10(6) cells vs. 10 ng/10(6) cells at a CsA dose of 5 micrograms/ml, P less than 0.05). Radioligand binding of 125I-hLH to testicular membranes was not affected by CsA, as CsA did not compete with hCG/LH for binding sites (25-28% binding with or without CsA). Similarly, the MIX-stimulated cAMP production was not affected by CsA (24.03 +/- 1.09 vs. 20.60 +/- 0.38 pmol/10(6) cells), suggesting that CsA does not inhibit the accumulation of the second messenger. However, when interstitial cells were incubated with CsA in the presence of cAMP, a significant dose-dependent decline in T secretion was observed (7 ng/10(6) cells vs. 20 ng/10(6) cells at a CsA dose of 5 micrograms/ml). To determine whether CsA inhibits the steps beyond cAMP stimulation of T secretion, the kinetic parameters (Km and Vmax) of steroidogenic enzymes, delta 4-3 keto-17 alpha hydroxylase (17 alpha-hydroxylase), and delta 4-3 keto-17 beta hydroxy steroid dehydrogenase (17B-HSD) were determined by using Michaelis Menten analysis. Results are shown in the presence of CsA vs. no CsA: Km and Vmax values for 17 alpha-hydroxylase were (2.32 vs. 7.98 microM) and (27.96 vs. 100.97 pmol/mg protein/min), respectively. For 17B-HSD the Km and Vmax were (2.14 vs. 1.52 microM) and (15 vs. 15 pmol/mg protein/min), respectively. These results indicate that CsA inhibits the activity of 17 alpha-hydroxylase uncompetitively and 17B-HSD activity competitively. In conclusion the primary site for CsA inhibition is the cAMP stimulation and, CsA inhibits T synthesis at multiple sites.
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PMID:The mechanism of cyclosporine's action in the inhibition of testosterone biosynthesis by rat Leydig cells in vitro. 131 Jan 71

17 beta-Hydroxysteroid dehydrogenase (17 beta HSD) deficiency is a rare cause of male pseudohermaphroditism, but is a frequent disorder among a highly inbred Arab population in the Gaza strip. Affected individuals are born and reared as females until puberty, when marked virilization occurs, leading in many cases to the spontaneous adoption of a male gender role. To investigate the mechanisms and site(s) of androgen production, we determined the gonadal and extragonadal steroid patterns in two postpubertal male pseudohermaphroditism patients, who were castrated and reared as females. Before castration, both patients had very high plasma levels of androstenedione (delta 4-A), normal or moderately low levels of testosterone (T), and significantly elevated delta 4-A/T ratios (P less than 0.01). Dihydrotestosterone (DHT) levels were normal or high, while the DHT/T ratios were lower than normal (P less than 0.01), suggesting enhanced 5 alpha-reductase activity. These abnormalities were much more severe in spermatic venous blood. 17 beta HSD deficiency was also found in the delta 5-pathway, by high dehydroepiandrosterone (DHEA) levels and very high dehydroxyepiandrosterone/delta 5-androstenediol (DHEA/delta 5-diol) ratios, and in peripheral tissue metabolites, by very high androsterone glucuronide/3 alpha-androstanediol glucuronide ratios (P less than 0.01). The estrogen pathway was also impaired (P less than 0.01), even though both estrone and estradiol levels were elevated. Gonadectomy significantly reduced all androgens and estrogens (P less than 0.01), but when compared to 42 castrated controls, both patients had lower delta 4-A and higher T levels. The delta 4-A/T ratio was lower than that in controls, indicating normal to enhanced extragonadal 17 beta HSD activity. A similar pattern was observed in the delta 5- and estrogen pathways. DHT levels were within normal limits, and 3 alpha-diol was moderately decreased. These data suggest that testicular 17 beta HSD activity is under a different genetic control from that in extragonadal tissues. Affected males lack the testicular enzyme, but their extragonadal 17 beta HSD activity is normal or enhanced. Together with enhanced 5 alpha-reductase activity, this represents a highly efficient compensatory mechanism for androgen and estrogen production after puberty.
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PMID:Mechanisms of androgen production in male pseudohermaphroditism due to 17 beta-hydroxysteroid dehydrogenase deficiency. 132 74

The regulation of steroid production by the placenta and fetal membranes is important for both the maintenance of pregnancy and the timing of parturition. 3 beta-Hydroxy-5-ene-steroid dehydrogenase/delta 5----delta 4-isomerase (3 beta HSD) catalyzes an obligatory step in the biosynthesis of steroid hormones. We have determined the localization of 3 beta HSD in the human placenta, fetal membranes, and umbilical cord throughout gestation by immunohistochemical analysis, using a polyclonal antibody raised in rabbits against a purified preparation of human placental 3 beta HSD. In placenta, immunoreactive (IR-) 3 beta HSD was localized in the syncytiotrophoblast and intermediate trophoblast cells at both villous and extravillous sites, but not in cytotrophoblast cells from 6 weeks gestation to term. At 6-7 weeks gestation, IR-3 beta HSD was distributed in the cytoplasm of syncytiotrophoblast in about half of placental villi. By 12-14 weeks, the syncytiotrophoblast of all placental villi stained positively for 3 beta HSD. In the fetal membranes, strong IR-3 beta HSD staining was found in the trophoblast and reticular layers of chorion and in invasive trophoblast cells in decidua, and weakly in decidual stromal cells and amniotic epithelium. No IR-3 beta HSD was found in amnion on the placental plate, but in the umbilical cord, IR-3 beta HSD was present in the amniotic epithelium and also in fibroblast cells in Warton's jelly. These observations demonstrate that the localization of 3 beta HSD immunoreactivity and, therefore, the presumed sites of delta 5- to delta 4-steroid interconversion throughout gestation are principally the syncytiotrophoblast and intermediate trophoblast cells in placenta and the trophoblast cells in chorion and decidua in fetal membranes.
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PMID:Immunohistochemical localization of 3 beta-hydroxy-5-ene-steroid dehydrogenase/delta 5----delta 4 isomerase in human placenta and fetal membranes throughout gestation. 138 75

The observation that adrenal 3 beta-hydroxysteroid dehydrogenase-delta 5----delta 4-isomerase (3 beta HSD) activity is greater in females than in males of both C57BL/6J and C3H/HeJ inbred strains of mice led us to test the hypothesis that this enzyme's activity within the adrenal gland may be modulated by gonadal steroids. Two weeks after sham-operation or castration, no castration effect was seen in adrenal 3 beta HSD activity, but the sex difference had been eliminated in C57BL/6J animals. Gonadal steroids were replaced in castrated animals of both sexes of C57BL/6J and C3H/HeJ mice. Daily injections of androgenic steroids (testosterone propionate or dihydrotestosterone) decreased adrenal 3 beta HSD activity in both sexes of both strains of mouse. Although estradiol benzoate did not alter adrenal 3 beta HSD activity in either sex or strain tested when the activity was expressed on a per adrenal gland basis, it did inhibit adrenal 3 beta HSD activity when expressed on a per milligram of adrenal tissue basis in C57BL/6J but not in C3H/HeJ animals. Histochemical staining for 3 beta HSD and the relationship between adrenal weight and the cross-sectional area of the zona fasciculata suggested that the adrenal zona fasciculata was the target of the inhibitory effects of androgens on adrenal 3 beta HSD activity.
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PMID:Gonadal steroids modulate adrenal fasciculata 3 beta-hydroxysteroid dehydrogenase-isomerase activity in mice. 154 17

This study describes the regulation of adrenal 3 beta-hydroxy-5-ene-steroid dehydrogenase/delta 5-delta 4-isomerase (3 beta HSD) expression and activity by ACTH and corticosterone, alone or in combination, in intact male and female rats as well as the effect of ACTH on 3 beta HSD expression and activity in the adrenals of hypophysectomized female animals. The effect of treatment on total 3 beta HSD mRNA levels was measured by dot blot hybridization using rat 3 beta HSD cDNA, while the specific regulation of type I and type II 3 beta HSD mRNAs was analyzed by ribonuclease protection assay. The concentration of 3 beta HSD protein was measured by Western blot, using cross-reacting antibodies raised against purified human placental 3 beta HSD, while 3 beta HSD enzymatic activity was measured by the conversion of [14C]dehydroepiandrosterone into [14C]androstenedione. The present data show that the trophic effect of ACTH on male and female rat adrenals is accompanied by increases in total 3 beta HSD mRNA, enzymatic activity, and protein content. Hypophysectomy, on the other hand, causes a marked decrease in 3 beta HSD mRNA levels and enzymatic activity, which is completely reversed by administration of ACTH. On the other hand, corticosterone treatment results in a marked inhibition of 3 beta HSD mRNA levels, enzymatic activity, and protein content in intact animals; this effect is probably mediated by a decrease in ACTH secretion. The present data show that ACTH and corticosterone, via its inhibitory action on ACTH secretion, have potent and opposite effects on the expression of two 3 beta HSD genes in the rat adrenal; a parallel effect is observed on both type I and II 3 beta HSD. Such data suggest that 3 beta HSD could well play a major role in the regulation of steroid formation in the adrenal cortex.
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PMID:Regulation of adrenal 3 beta-hydroxysteroid dehydrogenase/delta 5-delta 4-isomerase expression and activity by adrenocorticotropin and corticosterone in the rat. 165 93

In the steroidogenic pathway, 3 beta-hydroxysteroid dehydrogenase-isomerase (3 beta HSD) catalyzes the formation of hormonally active delta 4-3-ketosteroids from delta 5-3 beta-hydroxysteroids. In the present study the regulation of 3 beta HSD by ACTH action on bovine adrenocortical (BAC) cells in primary culture was evaluated. Western blot analysis was accomplished using an antibody against human placental 3 beta HSD. The relative molecular mass of 3 beta HSD in these cells was 45K, which was similar to that in human placenta. A significant effect of ACTH was not detected until day 6 of culture due to the high basal levels of the enzyme in BAC cells. Treatment of cells with ACTH on day 8 of culture resulted in a marked increase in the amount of 3 beta HSD protein, and this effect was correlated directly with enzymatic activity. The effects of ACTH were time and dose dependent, with an increase detectable only after 48 h of treatment; the maximal response was obtained with 10(-9) M ACTH. As demonstrated by Northern analysis, ACTH action was manifested by increasing the steady state level of 3 beta HSD mRNA. A human 3 beta HSD cDNA probe, which was used in this study, hybridized to a 1.7-kilobase species of BAC RNA. The effects of ACTH on 3 beta HSD activity and increases in 3 beta HSD protein and mRNA in BAC cells were mimicked by treatment with (Bu)2cAMP. The findings of this study suggest that ACTH controls 3 beta HSD gene expression in BAC cells by a cAMP-dependent mechanism similar to that involved in the expression of steroid hydroxylase genes. However, because the different stabilities of 3 beta HSD and hydroxylase proteins and/or mRNAs may play a critical role in determining the zone-specific steroids secreted from the adrenal cortex, other cAMP-dependent or independent regulatory mechanisms may also be important in regulating the expression of adrenal 3 beta HSD.
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PMID:Regulation of 3 beta-hydroxysteroid dehydrogenase/delta 5----4-isomerase expression by adrenocorticotropin in bovine adrenocortical cells. 184 95

The regulation of mRNA levels for delta 5-3 beta-hydroxysteroid dehydrogenase/delta 5----delta 4-isomerase (3 beta HSD), 17 alpha-hydroxylase/C17-20 lyase cytochrome P450 (P450(17 alpha] and cholesterol side-chain cleavage cytochrome P450 (P450scc) was studied in primary cultures of mouse Leydig cells. Treatment of Leydig cells with 8-bromo-cAMP (cAMP) was essential for expression of P450(17 alpha) mRNA, but not for 3 beta HSD. Treatment with cAMP caused a decrease in basal levels of 3 beta HSD mRNA. The addition of aminoglutethimide (AG), an inhibitor of cholesterol metabolism, to the cAMP-treated cultures resulted in increased expression of both 3 beta HSD and P450(17 alpha) mRNA levels. The addition of testosterone or the androgen agonist mibolerone to cAMP- plus AG-treated cultures reduced 3 beta HSD and P450(17 alpha) mRNA to levels comparable to those observed when cells were treated with cAMP only. The glucocorticoid dexamethasone reduced both basal and cAMP- plus AG-induced increases in 3 beta HSD mRNA, but not in P450(17 alpha) mRNA. Estradiol at a concentration of 1 microM had no effect on cAMP- plus AG-induced 3 beta HSD or P450(17 alpha) mRNA levels. The role of protein synthesis in mediating the cAMP induction of 3 beta HSD, P450(17 alpha), and P450scc was investigated. The addition of cycloheximide (10 micrograms/ml) to cAMP-treated cultures for 24 h completely suppressed both constitutive and cAMP-induced 3 beta HSD mRNA levels. Cycloheximide also repressed cAMP-induced levels of P450(17 alpha) to 12% of levels observed in the absence of cycloheximide. In sharp contrast, 24-h treatment with cycloheximide did not suppress cAMP induction of P450scc mRNA, but reduced basal levels by approximately 50%. A time course of induction by cAMP (50 microM) of P450(17 alpha) and P450scc mRNA showed very similar rates of increase in P450(17 alpha) and P450scc mRNA, with the greatest increase occurring between 12 and 24 h of treatment. The results of the study demonstrate that in normal mouse Leydig cells steady state levels of mRNA for 3 beta HSD, P450(17 alpha), and P450scc are differentially regulated. cAMP is required for maximal levels of all three mRNAs. There is high constitutive expression of 3 beta HSD and P450scc mRNA, while expression of P450(17 alpha) mRNA is absolutely dependent on cAMP stimulation. Endogenously produced testosterone negatively regulates the expression of cAMP-induced P450(17 alpha) and 3 beta HSD, while the glucocorticoid dexamethasone negatively regulates 3 beta HSD and P450scc.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Multiple mechanisms for regulation of 3 beta-hydroxysteroid dehydrogenase/delta 5----delta 4-isomerase, 17 alpha-hydroxylase/C17-20 lyase cytochrome P450, and cholesterol side-chain cleavage cytochrome P450 messenger ribonucleic acid levels in primary cultures of mouse Leydig cells. 187 81

In the steroidogenic pathways present in the gonads and adrenal cortex, 3 beta-hydroxysteroid dehydrogenase isomerase (3 beta HSD) is a key enzyme which controls the formation of delta 4-3-ketosteroids from delta 5-3 beta-hydroxysteroids. Herein, we used an antibody against human placental 3 beta HSD and a rat testicular 3 beta HSD cDNA probe to study the expression of rat liver 3 beta HSD mRNA and protein. Rat liver microsomal 3 beta HSD activity has been previously reported to exhibit a significant sex difference, with much higher activity in the male. We have shown an age-dependent increase in levels of immunoreactive 3 beta HSD through the time of maturation of the male rat. The immunoreactive protein, of similar molecular size to the human placental and rat testicular 3 beta HSD, was localized to the microsomal fraction of liver and was concentrated in pericentral locations. Immunoreactive protein was not detected in liver of immature (before 25 days of age) rats of either sex or in adult female liver. Northern blot analysis of liver and testicular RNA with a rat testicular 3 beta HSD cDNA probe revealed the presence of a 1.6-kilobase mRNA species in addition to the major 2.1-kilobase mRNA species in adult male liver, neither of which was detected in immature or adult female liver RNA. Hypophysectomy of female rats or treatment with testosterone implants caused induction of liver 3 beta HSD protein, while continuous infusion of GH to male rats decreased the level of 3 beta HSD protein. Similarly, the levels of the mRNA species were decreased after GH treatment. Using [3 alpha-3H]dehydroepiandrosterone as substrate for 3 beta HSD activity, we determined the apparent Km for liver microsomal NAD(+)-dependent 3 beta HSD activity to be 20 microM in both adult male and female liver and was much greater than the Km of rat Leydig tumor 3 beta HSD activity (0.2 microM). Liver 3 beta HSD activity was inhibited by trilostane, a proven inhibitor of gonadal and adrenal 3 beta HSD activity. A rat liver 3 beta HSD cDNA was isolated from a male liver cDNA library that was closely related to the type II 3 beta HSD form of rat ovary but different from type III liver 3 beta HSD. The enzyme obtained upon expression of this cDNA had properties characteristic of male-specific NAD(+)-dependent liver microsomal 3 beta HSD (i.e. high apparent Km for dehydroepiandrosterone) and distinct from those of the high affinity gonadal type I 3 beta HSD.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Regulation of expression of male-specific rat liver microsomal 3 beta-hydroxysteroid dehydrogenase. 194 5


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