Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:Q7LGC8 (HSD)
 3,196 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

An enzyme exhibiting both 3 beta and 20 alpha steroid reductase activities from calf fetal red blood cells was purified to homogeneity as judged by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. 3 beta,20 alpha-Hydroxysteroid oxidoreductase (3 beta,20 alpha-HSD) was found to be a single-stranded polypeptide with a molecular weight of 55 000 +/- 1 000 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Sephadex G-100 chromatography. The amino acid composition of 3 beta,20 alpha-HSD was obtained. 17 beta-Hydroxy-5 alpha-androstan-3-one and progesterone were substrates for the enzyme's 3 beta and 20 alpha reductase activities, respectively, which required NADPH for both 3 beta [Km = 9.4 microM; Vmax = 2.4 nmol min-1 (nmol of enzyme)-1] and 20 alpha [Km = 2.5 microM; Vmax = 2.4 nmol min-1 (nmol of enzyme)-1] reductase activities. 17 beta-Hydroxy-5 alpha-androstan-3-one competitively inhibited (Ki = 35 microM) 20 alpha reduction of progesterone. Incubating 3 beta,20 alpha-HSD with 19-nortestosterone 17-bromoacetate at pH 7.0 and 25 degrees C caused simultaneous, time-dependent, and irreversible losses of 3 beta and 20 alpha activities by a first-order kinetic process. Similar incubations with either of the 3 beta or 20 alpha substrates present at concentrations equal to their respective Km values practically doubled the time required for loss of 3 beta and 20 alpha enzyme activities. These data lead us to conclude that the active site of 3 beta,20 alpha-HSD contains 3 beta and 20 alpha dual activity.
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PMID:Dual activity at an enzyme active site: 3 beta,20 alpha-hydroxysteroid oxidoreductase from fetal blood. 695 29

The enzyme 3 beta-hydroxysteroid dehydrogenase (3 beta HSD) plays an essential role in the biosynthesis of all steroid hormones. We previously reported the isolation, characterization, and tissue-specific expression of four distinct but highly homologous 3 beta HSD cDNAs (forms I, II, III, and IV). Enzymatic characterization of three of these isoforms demonstrated that mouse 3 beta HSD I and III function as dehydrogenase/isomerases, but 3 beta HSD IV functions exclusively as a 3-ketosteroid reductase. We now report the isolation and characterization of an additional distinct mouse 3 beta HSD cDNA, 3 beta HSD V, which is expressed in the liver of male mice beginning in late puberty. Similar to 3 beta HSD IV, 3 beta HSD V functions exclusively as a 3-ketosteroid reductase converting an active androgen, dihydrotestosterone (DHT), into an inactive androgen, 5 alpha-androstane-3 beta,17 beta-diol. Expressed 3 beta HSD V, however, exhibits a considerably lower apparent Michaelis-Menten constant (Km) value for DHT than 3 beta HSD IV (0.47 microM vs. 2.2 microM, respectively). The complete predicted amino acid sequence of 3 beta HSD II is also reported. The predicted amino acid sequence of mouse 3 beta HSD V reveals that this new form is more closely related to the 3-ketosteroid reductases, mouse 3 beta HSD IV and rat III (93 and 84% identity, respectively), than to the other rodent isoforms that share less than 75% identity.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:The mouse 3 beta-hydroxysteroid dehydrogenase multigene family includes two functionally distinct groups of proteins. 749 Nov 13

A novel variant of 11 beta-hydroxysteroid dehydrogenase 1 (11 beta-HSD1) mRNA was identified from the ovine liver by reverse transcription-polymerase chain reaction (RT/PCR), and was named 11 beta-HSD1C mRNA. Sequence analysis of the RT-PCR product revealed that 11 beta-HSD1C mRNA was the product of an alternative exon-splicing within the 11 beta-HSD1 gene in which exon 5 was spliced out. Although it caused a deletion of 48 amino acids in the deduced 11 beta-HSD1 protein, this alternative splicing did not result in a shift within the predicted open reading frame of 11 beta-HSD1 cDNA. Thus, 11 beta-HSD1C mRNA was predicted to code for a protein of 244 amino acids. Using RT-PCR, we also examined the expression of 11 beta-HSD1C mRNA in ovine fetal organs and in maternal myometrium, endometrium, chorion, amnion and placenta. The 11 beta-HSD1C mRNA was expressed ubiquitously, similar to 11 beta-HSD1A mRNA, but at a lower abundance. Furthermore, since levels of 11 beta-HSD1C mRNA were directly related to those of 11 beta-HSD1A mRNA, there is no tissue-specificity for this shorter transcript and the only factor regulating its production appears to be 11 beta-HSD1A mRNA itself. To determine whether 11 beta-HSD1C mRNA encoded a functional enzyme, we inserted the cDNA into the expression vector pRc/CMV, and transfected the construct into Chinese hamster ovary cells. The transfected cells expressed a mRNA of expected size but contained no detectable 11 beta-HSD activity. When combined with cellular extracts of 11 beta-HSD1A cDNA transfected cells, they also did not alter either the dehydrogenase or reductase activity. The functional significance of the 11 beta-HSD1 transcript lacking exon 5 (11 beta-HSD1C mRNA) remains to be determined.
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PMID:Identification and tissue distribution of a novel variant of 11 beta-hydroxysteroid dehydrogenase 1 transcript. 749 5

Pathways of testosterone metabolism in tissue slices and cell suspensions of human benign hyperplastic prostate (BPH) tissue and human prostate cancer cell lines (DU145, HPC-36M, PC-3/MA2 and LNCaP) were investigated. Thin layer chromatography analysis was used to identify the following tritiated metabolites: testosterone, 5 alpha-dihydrostestosterone (DHT), 5 alpha-androstane-3 alpha/3 beta-17 beta-diol (androstanediols), 4-androstene-3,17-dione (androstenedione) and 5 alpha-androstanedione. The predominant pathway for testosterone metabolism in BPH was via 5 alpha-reductase producing 5 alpha-dihydrotestosterone (71% and 75% total metabolites in slices and suspensions incubated for 24 h, respectively). The cancer cell lines DU145 and HPC-36M resembled BPH by metabolizing testosterone predominantly to DHT (68% and 82% total metabolites, respectively), although the rate of metabolism was much lower in the cell lines (0.099 and 0.05 pmol testosterone/mg protein/h in DU145 and HPC-36M) compared to the BPH cell suspensions (6.4 pmol testosterone/mg protein/h). In contrast, PC-3/MA2 contained high 17 beta-HSD activity forming large amounts of 4-androstene-3,17-dione (84% total metabolites), converting testosterone at a rate faster (12.8 pmol testosterone/mg protein/h) than the BPH cell suspensions. LNCaP rapidly converted testosterone exclusively to a glucuronide conjugate (7.4 pmol testosterone/mg protein/h), although after incubation with [3H]-4-androstene-3,17-dione, 5 alpha-reductase activity was demonstrated. LNCaP was the only cell line whose growth and colony-forming ability was stimulated by testosterone and DHT. BPH and all the cell lines tested had 5 alpha-reductase activity, but only the prostate tissue and the cell lines DU145 and HPC-36M converted testosterone predominantly to DHT.
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PMID:Comparison of testosterone metabolism in benign prostatic hyperplasia and human prostate cancer cell lines in vitro. 751 39

11 beta-Hydroxysteroid dehydrogenase (11 beta-HSD), responsible for the interconversion of hormonally active cortisol to inactive cortisone, dictates specificity for the mineralocorticoid receptor (MR) in the distal nephron and colon. Two isoforms of human 11 beta-HSD have been cloned, an NADP(H)-dependent (type 1) dehydrogenase/oxo-reductase enzyme, and a high-affinity NAD-dependent (type 2) unidirectional dehydrogenase. Using the reverse-transcriptase polymerase chain reaction (RT-PCR) amplification of RNA extracted from human adult tissues, type 1 11 beta-HSD mRNA was found in decidua, placenta, liver, lung, spleen, kidney medulla, cerebellum and pituitary, but was absent in kidney cortex, sigmoid and rectal colon, salivary gland and thyroid. In contrast, type 2 11 beta-HSD mRNA was found only in placenta and in the classical mineralocorticoid target tissues, kidney cortex, kidney medulla, sigmoid and rectal colon, salivary gland, and colonic epithelial cell lines (AAC1 and RGC28). In situ hybridization studies of renal cortex, cortico-medullary junction and medulla using a 35S-labeled antisense cRNA probe for type 2 human 11 beta-HSD, revealed specific localization of type 2 11 beta-HSD mRNA expression exclusively to renal cortical and medullary collecting ducts. Type 1 and type 2 isoforms of human 11 beta-HSD are expressed in a distinct tissue-specific fashion, in keeping with the proposed differences in their physiological roles. Type 2 11 beta-HSD is found predominantly in mineralocorticoid target tissues where it serves to protect the MR in an autocrine fashion.
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PMID:Detection of human 11 beta-hydroxysteroid dehydrogenase isoforms using reverse-transcriptase-polymerase chain reaction and localization of the type 2 isoform to renal collecting ducts. 754 19

The cellular localization of 11 beta-hydroxysteroid dehydrogenase 2 (11 beta-HSD2) gene expression in the ovine adrenal gland was determined by in situ hybridization histochemistry. 11 beta-HSD2 mRNA was localized exclusively to the adrenal cortex of the adult sheep, and within the cortex the mRNA was highly expressed in the zona fasciculata and zona reticularis with relatively low expression in the zona glomerulosa. Radiometric conversion assay using adrenal cortical tissues revealed extremely high levels of 11 beta-HSD activity which was characteristic of 11 beta-HSD2 in that it was NAD-dependent and displayed a Km for cortisol of 41 +/- 4 nM. This indicates that 11 beta-HSD2 mRNA within the ovine adrenal gland is translated and functional with respect to enzymatic activity. In marked contrast, 11 beta-HSD1 mRNA was undetectable in either the cortex or medulla of adult sheep adrenal glands. In conclusion, we have demonstrated, for the first time, the zonal localization of 11 beta-HSD2 mRNA and the presence of 11 beta-HSD2 activity in the adult sheep adrenal cortex. The adrenal 11 beta-HSD2 may function to (1) regulate the rate of cortisol secretion by adrenocortical cells; (2) protect these cells from high levels of locally produced glucocorticoids; and/or (3) provide an important source of circulating cortisone, which can be activated by the action of 11 beta-HSD1 reductase in organs such as the liver.
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PMID:Cellular localization of 11 beta-hydroxysteroid dehydrogenase 2 gene expression in the ovine adrenal gland. 755 71

11 beta-Hydroxysteroid dehydrogenase (11 beta HSD) catalyzes the conversion of corticosterone to inert 11-dehydrocorticosterone, thus regulating glucocorticoid access to intracellular receptors. This type 1 isoform (11 beta HSD-1) is a bidirectional NADPH(H)-dependent enzyme in vitro and is highly expressed in liver, where it is regulated by glucocorticoids, thyroid hormones, estrogen, and GH in vivo. In humans in vivo, enzyme inhibition alters glucose homeostasis, an effect thought to be mediated in the liver. However, detailed investigation of the biology of 11 beta HSD-1 in liver, its function, regulation, and indeed even reaction direction, has been hampered by the lack of clonal hepatic cell lines that express 11 beta HSR-1. Studies of nonhepatic cell lines have suggested that 11 beta HSD-1 is directly regulated by hormones, and transfection of nonhepatic cell lines has sown that reaction direction varies between cell types, possibly reflecting intracellular cosubstrate (NADP+/NADPH) ratios or PH. To investigate reaction direction and gene regulation of 11 beta HSD-1 in hepatocytes, we defined conditions for primary culture of adult rat hepatocytes that maintain high 11 beta HSR-1 messenger RNA expression. In intact primary hepatocytes over a wide range of steroid concentrations (2.5-250 nM), 11 beta-reduction was the predominant reaction direction [33.5 +/- 0.5% conversion of 11-dehydrocorticosterone (25 nM) to corticosterone after 30 min], with undetectable 11 beta-dehydrogenation. However, homogenates of hepatocyte cultures showed plentiful 11 beta-dehydrogenase activity. Treatment of hepatocyte cultures with the metabolic inhibitors sodium azide (5 nM) and KCN (1 nM) altered cellular NADP+/NADPH ratios from 0.244 +/- 0.042 in controls to 0.020 +/- 0.001 and 0.152 +/- 0.009, respectively, but had no effect on 11 beta-reductase or 11 beta- dehydrogenase activity. High concentrations of KCN (10 mM) modestly increased 11 beta-reductase activity (32.4 +/- 1.7% to 48.8 +/- 0.5%, whereas 11 beta-dehydrogenation remained at the limit of detection. Manipulation of culture medium pH (6.2-8.0) had no effect on enzyme activity. Dexamethasone (10-7 M) induced hepatocyte 11 beta-reductase activity from 23.4 +/- 0.7% to only weakly affects reaction direction. Glucocorticoid and insulin regulation of hepatic 11 beta HSD-1 is directly mediated, but other hormonal controls are either lost in culture or mediated indirectly. This primary hepatocyte culture system will allow investigation of the control of 11 beta-reductase activity and its implications for glucocorticoid-regulated hepatic functions.
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PMID:11 beta-hydroxysteroid dehydrogenase is an exclusive 11 beta- reductase in primary cultures of rat hepatocytes: effect of physicochemical and hormonal manipulations. 758 3

11 beta-Hydroxysteroid dehydrogenase (11-HSD) catalyzes the conversion of cortisol to cortisone and corticosterone to 11-dehydrocorticosterone. This activity may be required to confer normal ligand specificity upon the mineralocorticoid receptor. Although an isozyme of 11-HSD was previously isolated from rat liver, a different isozyme is apparently expressed in mineralocorticoid target tissues. We isolated a sheep kidney cDNA clone encoding this isozyme by expression screening using Xenopus oocytes. The cDNA is 1.8 kb in length and encodes a protein of 427 amino acid residues with a predicted M(r) of 46,700. When expressed in oocytes, this enzyme functions as an NAD(+)-dependent 11 beta-hydrogenase with very high affinity for steroids, but it has no detectable reductase activity. It is 37% identical in amino acid sequence to an NAD(+)-dependent isozyme of 17 beta-hydroxysteroid dehydrogenase, but only 20% identical to the NADP(+)-dependent liver isozyme of 11-HSD. It is expressed at high levels in the kidney and adrenal and at lower levels in the colon. The corresponding gene is present in a single copy in the sheep genome. In humans, this gene is a candidate locus for the syndrome of apparent mineralocorticoid excess, a form of hypertension postulated to result from 11-HSD deficiency in mineralocorticoid target tissues.
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PMID:Cloning of cDNA encoding an NAD(+)-dependent isoform of 11 beta-hydroxysteroid dehydrogenase in sheep kidney. 758 2

The classical form of the enzyme 5-ene-3 beta-hydroxysteroid dehydrogenase/isomerase (3 beta HSD), expressed in adrenal glands and gonads, catalyzes the conversion of 5-ene-3 beta-hydroxysteroids to 4-ene-3-ketosteroids, an essential step in the biosynthesis of all active steroid hormones. To date, four distinct mouse 3 beta HSD cDNAs have been isolated and characterized. These cDNAs are expressed in a tissue-specific manner and encode proteins of two functional classes. Mouse 3 beta HSD I and III function as 3 beta-hydroxysteroid dehydrogenases and 5-en-->4-en isomerases using NAD+ as a cofactor. The enzymatic function of 3 beta HSD II has not been completely characterized. Mouse 3 beta HSD IV functions only as a 3-ketosteroid reductase using NADPH as a cofactor. The predicted amino acid sequences of the four isoforms exhibit a high degree of identity. Forms II and III are 85 and 83% homologous to form I. Form IV is most distant from the other three with 77 and 73% sequence identity to I and III, respectively. 3 beta HSD I is expressed in the gonads and adrenal glands of the adult mouse. 3 beta HSD II and III are expressed in the kidney and liver with the expression of form II greater in kidney and form III greater in liver. Form IV is expressed exclusively in the kidney. Although the amino acid composition of forms I, III and IV predicts proteins of the same molecular weight, the proteins have different mobilities on SDS-polyacrylamide gel electrophoresis. This characteristic allows for differential identification of the expressed proteins. The four structural genes encoding the different isoforms are closely linked within a segment of mouse chromosome 3 that is conserved on human chromosome 1.
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PMID:The murine 3 beta-hydroxysteroid dehydrogenase multigene family: structure, function and tissue-specific expression. 762 43

In the brain, the 5 alpha-reductase converting testosterone (T) is present both in neurons and in glial cells, even if it prevails in neurons; the 3 alpha-hydroxysteroid-dehydrogenase (3 alpha-HSD), the enzyme converting dihydrotestosterone (DHT) into 3 alpha-diol, is particularly concentrated in type 1 astrocytes. In glial cells, since the 5 alpha-reductase is activated by a cAMP analogue, PKA seems to be involved in the control of this enzyme, postulating that nervous inputs utilizing cAMP as the second messenger might modify the activity of this enzyme in glial cells. Moreover, the results indicate that, in type 1 astrocytes, both the 5 alpha-reductase and the 3 alpha-HSD are stimulated by the co-culture with neurons and by the addition of neuron-conditioned medium, suggesting that secretory products released by neurons might intervene in the control of glial cell function.
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PMID:Metabolism of steroids in pure cultures of neurons and glial cells: role of intracellular signalling. 762 76


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