Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:Q8NEX9 (reductase)
 26,410 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The regulation of 11 beta-hydroxysteroid dehydrogenase (11 beta HSD) was studied in cultured human skin fibroblasts. 11-Oxo-reductase activity was 5- to 10-fold higher than 11 beta-dehydrogenase activity. Cells treated with 100 nM dexamethasone (Dex) showed a 3-fold increase in the maximum velocity of both activities without a change in the Km values. Dex induction of 11 beta HSD was half-maximal at 48 h and was blocked by glucocorticoid receptor antagonists. Nonglucocorticoid steroids were ineffective. Removal of serum from the culture medium increased maximum velocity values up to 6-fold. Treatment of cells grown in the absence of serum with 8-bromo-cAMP, phorbol esters, or insulin decreased both 11 beta HSD activities. The effects of Dex treatment and serum removal were additive and were blocked by cycloheximide and actinomycin-D. In all experiments both 11 beta HSD activities were modulated in parallel. Both cortisone (200 nM) and cortisol increased the aromatase activity of fibroblasts in the presence of serum. Prior induction of 11 beta HSD by serum removal increased the potency of cortisone from 10-15% to 50% that of cortisol. We conclude that 1) in human fibroblasts 11 beta HSD appears to be a single protein that is under multifactorial regulation; 2) 11 beta HSD may increase or decrease cortisol availability to glucocorticoid receptors; and 3) plasma cortisone levels may be important in assessing glucocorticoid status.
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PMID:Regulation of 11 beta-hydroxysteroid dehydrogenase activity in human skin fibroblasts: enzymatic modulation of glucocorticoid action. 185 64

In the kidney, conversion of cortisol to cortisone by the enzyme 11 beta-hydroxysteroid dehydrogenase protects mineralocorticoid receptors from cortisol. In the liver, a different isoform of the enzyme favors 11 beta-reductase conversion of cortisone to cortisol. We have tested the hypothesis that hepatic 11 beta-reductase enhances glucocorticoid receptor activation in the liver by inhibiting the enzyme with carbenoxolone and observing effects on insulin sensitivity. Seven healthy males took part in a double blind randomized cross-over study in which oral carbenoxolone (100 mg every 8 h) or placebo was administered for 7 days. Euglycemic hyperinsulinemic clamp studies were then performed, including measurement of forearm glucose uptake. Carbenoxolone increased whole body insulin sensitivity (M values for dextrose infusion rates, 41.1 +/- 2.4 mumol/kg.min for placebo vs. 44.6 +/- 2.3 for carbenoxolone; P < 0.03), but had no effect on forearm insulin sensitivity. We infer that carbenoxolone, by inhibiting hepatic 11 beta-reductase and reducing intrahepatic cortisol concentration, increases hepatic insulin sensitivity and decreases glucose production. Thus, plasma cortisone provides an inactive pool that can be converted to active glucocorticoids at sites where 11 beta-reductase is expressed, abnormal hepatic 11 beta-reductase activity might be important in syndromes of insulin resistance, and manipulation of hepatic 11 beta-reductase may be useful in treating insulin resistance.
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PMID:Carbenoxolone increases hepatic insulin sensitivity in man: a novel role for 11-oxosteroid reductase in enhancing glucocorticoid receptor activation. 759 19

Recent studies have demonstrated that the interconversion of active and inactive glucocorticoids plays a key role in determining the specificity of the mineralocorticoid receptor and controlling local tissue glucocorticoid receptor activation. Two distinct isoforms of the enzyme 11 beta-hydroxysteroid dehydrogenase (11 beta-HSD) have been identified. 11 beta-HSD1 is NADPH-dependent and at its major site of action (the liver) is a reductase, converting cortisone to cortisol (11-dehydrocorticosterone to corticosterone in the rat). 11 beta-HSD2 is NAD-dependent, is present in tissues such as the kidney and placenta, and converts cortisol to cortisone (corticosterone to 11-dehydrocorticosterone in the rat). Congenital or acquired deficiency of 11 beta-HSD2 produces the syndrome of apparent mineralocorticoid excess (SAME) in which cortisol gains access to the unprotected nonspecific mineralocorticoid receptor. The congenital deficiency is associated with mutations in the gene encoding the kidney isoform of 11 beta-HSD2; the acquired form results from inhibition of the enzyme by licorice, carbenoxolone, ACTH-dependent steroids in the ectopic ACTH syndrome, and possibly circulating inhibitors of the enzyme. This paper focuses on recent evidence, which suggest that low levels of placental 11 beta-HSD2 result in increased exposure of the fetus to maternal glucocorticoid and low birth weight. In animal studies using the rat we have shown that birth weight is correlated positively and placental weight negatively with the level of placental 11 beta-HSD. Thus animals with low birth weight and large placentae were those likely to be exposed to the highest level of maternal glucocorticoid. In man a similar relationship was found with birth weight being significantly correlated either with placental 11 beta-HSD activity or with the extent of cortisol inactivation by isolated perfused placental cotyledons. Administration of dexamethasone (which is poorly metabolized by placental 11 beta-HSD2) to pregnant rats resulted in decreased birth weight and the development of hypertension in the pups when adult. The same results were obtained when pregnant rats were given carbenoxolone, an inhibitor of placental 11 beta-HSD2. Low protein diet during pregnancy in the rat resulted in low birth weight of the pups, increased placental weight but decreased placental 11 beta-HSD activity, and adult hypertension. Thus increased glucocorticoid exposure of the fetus secondary to a failure of the normal inactivation of maternal glucocorticoid by the placental may be an important mechanism linking changes in the in utero environment and common adult diseases.
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PMID:11 beta-Hydroxysteroid dehydrogenases: key enzymes in determining tissue-specific glucocorticoid effects. 873 12

Endogenously released or exogenously administered glucocorticosteroids are relevant hormones for controlling inflammation. Only 11beta-hydroxy glucocorticosteroids, but not 11-keto glucocorticosteroids, activate glucocorticoid receptors. Since we found that glomerular mesangial cells (GMC) express 11beta-hydroxysteroid dehydrogenase 1 (11beta-OHSD1), which interconverts 11-keto glucocorticosteroids into 11beta-hydroxy glucocorticosteroids (cortisone/cortisol shuttle), we explored whether 11beta-OHSD1 determines the antiinflammatory effect of glucocorticosteroids. GMC exposed to interleukin (IL)-1beta or tumor necrosis factor alpha (TNF-alpha) release group II phospholipase A2 (PLA2), a key enzyme producing inflammatory mediators. 11beta-hydroxy glucocorticosteroids inhibited cytokine-induced transcription and release of PLA2 through a glucocorticoid receptor-dependent mechanism. This inhibition was enhanced by inhibiting 11beta-OHSD1. Interestingly, 11-keto glucocorticosteroids decreased cytokine-induced PLA2 release as well, a finding abrogated by inhibiting 11beta-OHSD1. Stimulating GMC with IL-1beta or TNF-alpha increased expression and reductase activity of 11beta-OHSD1. Similarly, this IL-1beta- and TNF-alpha-induced formation of active 11beta-hydroxy glucocorticosteroids from inert 11-keto glucocorticosteroids by the 11beta-OHSD1 was shown in the Kiki cell line that expresses the stably transfected bacterial beta-galactosidase gene under the control of a glucocorticosteroids response element. Thus, we conclude that 11beta-OHSD1 controls access of 11beta-hydroxy glucocorticosteroids and 11-keto glucocorticosteroids to glucocorticoid receptors and thus determines the anti-inflammatory effect of glucocorticosteroids. IL-1beta and TNF-alpha upregulate specifically the reductase activity of 11beta-OHSD1 and counterbalance by that mechanism their own proinflammatory effect.
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PMID:Tumor necrosis factor alpha and interleukin 1beta enhance the cortisone/cortisol shuttle. 922 48

Genetic variation of the glucocorticoid receptor (GR) locus is associated with differences in blood pressure. To define the intermediate phenotypes associated with this variation, we investigated the biochemical and clinical significance of a BclI restriction fragment length polymorphism of the GR locus in 64 normal male volunteers. Blood samples were genotyped as either AA (homozygous large allele; n = 6), Aa (heterozygous; n = 51), or aa (homozygous small allele, n = 7). Four primary glucocorticoid variables were measured including GR binding characteristics and glucocorticoid-sensitive lysozyme release of leukocytes in vitro and the blanching response of forearm skin to budesonide. A large number of secondary variables (urinary and plasma steroid measurements, blood pressure and indices of body fat metabolism, and routine biochemical and hematological measurements) were also considered. In vivo sensitivity to budesonide was greater in AA than aa individuals (mean +/- SE EC50 values: 13 +/- 5 and 42 +/- 10 ng; P < 0.01). In contrast, leukocytes of AA subjects tended to have lower affinity and reduced sensitivity for dexamethasone, although these effects were not statistically significant. Based on urinary steroid measurements, 11 beta-hydroxysteroid dehydrogenase activity [ratio of tetrahydrocortisol (THF) to tetrahydrocortisone (THE) metabolites] was not affected by genotype. The relative activities of 5 alpha- and 5 beta-reductase activity (allo-THF/THF + THE) appeared lower in AA than aa subjects (0.22 +/- 0.04 cf. 0.33 +/- 0.06; P < 0.005) but were not judged to be significantly different when corrected for multiple comparisons. Single and multivariate analyses were carried out to determine which variables influence GR binding characteristics and glucocorticoid responsiveness and to see whether cardiovascular risk factors (blood pressure and body fat) were influenced by glucocorticoid-dependent functions. Only 15-20% of the variations in the dissociation constant (Kd) and maximum binding capacity (Bmax) were influenced by other variables; plasma cholesterol was the most important for affinity and plasma sodium concentration for binding capacity. Multivariate analysis showed that several factors including GR genotype and urinary cortisol account for 10% of the variation of in vivo responses to glucocorticoid hormones; plasma calcium concentration was the only variable that contributed to in vitro sensitivity of leukocytes to dexamethasone. Glucocorticoid-dependent responses were of negligible importance in determining blood pressure or percentage body fat within the narrow physiological ranges of the present study. We conclude that GR genotype affects steroid sensitivity in a tissue-specific manner because of altered GR function or possibly because of linkage to a locus that controls hormone access to the receptor by influencing steroid metabolism.
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PMID:Glucocorticoid receptor polymorphism, skin vasoconstriction, and other metabolic intermediate phenotypes in normal human subjects. 962 6

To evaluate the potential roles that both receptors and enzymes play in corticosteroid regulation of intestinal function, we have determined glucocorticoid receptor (GR), mineralocorticoid receptor (MR), and 11beta-hydroxysteroid dehydrogenase (11beta-HSD) expression in intestinal epithelial cells. GR and MR mRNA and receptor binding were ubiquitously expressed in epithelial cells, with receptor levels higher in ileum and colon than jejunum and duodenum. RNase protection analysis showed that 11beta-HSD1 was not expressed in intestinal epithelial cells, and enzyme activity studies detected no 11-reductase activity. 11beta-HSD2 mRNA and protein were demonstrated in ileal and colonic epithelia; both MR and GR binding increased when enzyme activity was inhibited with carbenoxolone. Duodenal and jejunal epithelial cells showed very little 11beta-HSD2 mRNA and undetectable 11beta-HSD2 protein; despite minor (<7%) dehydrogenase activity in these cells, enzyme activity did not alter binding of corticosterone to either MR or GR. These findings demonstrate the ubiquitous but differential expression of MR and GR in intestinal epithelia and that 11beta-HSD2 modulates corticosteroid binding to both MR and GR in ileum and proximal and distal colon but not in duodenum or jejunum.
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PMID:Corticosteroid receptors and 11beta-hydroxysteroid dehydrogenase isoforms in rat intestinal epithelia. 1048 78

Cytochrome P-4503A, CYP2B, and P-450 reductase are induced by glucocorticoids, antiglucocorticoids such as pregnenolone 16alpha-carbonitrile, and drugs such as rifampin and phenobarbital. Although the pregnane X receptor is reported to mediate steroid and drug activation of CYP3A via a conserved cis-element in CYP3A genes, discrepancies exist between the induction of the endogenous CYP3A genes and the activation of the pregnane X receptor. It is a formal possibility that the glucocorticoid receptor may account for some of these discrepancies. To determine the requirement in vivo of the glucocorticoid receptor in expression of CYP3A and CYP2B, we compared the induction of these proteins in the livers of normal mice and mice with a targeted mutation in the glucocorticoid receptor. Mice lacking the glucocorticoid receptor show no difference in constitutive hepatic expression of CYP3A but show a decrease in the level of CYP2B. Glucocorticoid receptor-deficient mice challenged with either dexamethasone or pregnenolone 16alpha-carbonitrile failed to induce CYP2B proteins, whereas CYP2B was readily induced in (+/+) mice. In contrast, CYP3A and P-450 reductase proteins were induced by either inducer in wild-type and glucocorticoid receptor-null mice. Similarly, rifampin induced CYP3A in either wild-type or glucocorticoid receptor-null mice. Despite reports that rifampin is a nonsteroidal ligand for the human glucocorticoid receptor, rifampin failed to induce tyrosine aminotransferase in mice regardless of glucocorticoid receptor genotype, and rifampin did not compete for ligand binding to either mouse or human glucocorticoid receptor. Phenobarbital induced CYP3A, CYP2B, and P-450 reductase in all mice, but the amplitude of induction was diminished 37% in glucocorticoid receptor-null mice. Thus, there are distinctly different essential requirements of CYP3A, CYP2B, and P-450 reductase genes for the glucocorticoid receptor in their induction by steroids and drugs.
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PMID:The glucocorticoid receptor is essential for induction of cytochrome P-4502B by steroids but not for drug or steroid induction of CYP3A or P-450 reductase in mouse liver. 1068 70

Both central obesity and osteoporosis are common findings in states of glucocorticoid excess. In many tissues, including adipose tissue, hydroxysteroid dehydrogenase type 1 (11beta-HSD1) catalyses the inter-conversion of active glucocorticoid, cortisol (F) and inactive cortisone (E) and regulates exposure to the glucocorticoid receptor. As such, factors which regulate 11beta-HSD1 are likely to have an important role in adipose tissue and bone physiology. Using primary cultures of human adipose stromal cells we have investigated the effect of various factors present within the adipocyte microenvironment for their effects on 11beta-HSD1 expression. IGF-1 caused a dose dependant inhibition of 11beta-HSD1 activity in both subcutaneous and omental stromal cells. Additionally, TNFalpha treatment increased 11beta-HSD1 reductase activity and mRNA expression. In adult human bone, 11beta-HSD1, but not 11beta-HSD2, expression was demonstrated using enzyme activity studies, RT-PCR and immunohistochemistry. In contrast to liver and adipose tissues, where reductase activity predominates, both reductase and dehydrogenase activities of 11beta-HSD1 were evident in bone chips and primary cultures of human osteoblasts. The action of growth factors and cytokines on glucocorticoid sensitive tissues such as adipose tissue and bone may be mediated by modulation of local glucocorticoid metabolism at a pre-receptor level.
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PMID:The role of 11 beta-hydroxysteroid dehydrogenase in central obesity and osteoporosis. 1119 47

In sites of inflammation there is a change in the equilibrium between the enzymes that inactivate cortisol by conversion to cortisone and those that reactivate cortisone by conversion to cortisol. Current evidence suggests that during an immune response with a Type 1 cytokine profile such as tuberculosis, there is locally enhanced reductase activity with locally increased cortisol concentrations due to recruitment of cortisone. This results in enhanced cortisol mediated feedback on the inflammatory process, and deviation of the response towards Type 2. Preliminary data suggest that eventually, in the presence of Type 2 cytokine polarization, the enzyme equilibrium may reverse again and cortisol is then locally inactivated to cortisone. Together with changes in glucocorticoid receptor expression and function this may result in local cortisol resistance and susceptibility to tissue damage mediated by proinflammatory cytokines. These observations help to explain the sequence of events in several infectious, inflammatory and autoimmune diseases.
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PMID:Local regulation of glucocorticoid activity in sites of inflammation. Insights from the study of tuberculosis. 1126 21

Glucocorticoids are involved in the modulation of the release of parturition hormones from the fetal membranes and placenta, where their actions are determined by the prereceptor glucocorticoid metabolizing enzyme 11beta-hydroxysteroid dehydrogenase (11beta-HSD). Two distinct isozymes of 11beta-HSD have been characterized. In the fetal membranes, 11beta-HSD1 is the predominate isozyme; it converts biologically inert 11-ketone glucocorticoid metabolites into active glucocorticoids. Sequence analysis of the cloned 11beta-HSD1 gene revealed a putative glucocorticoid response element in the promoter region. However, whether glucocorticoids modulate 11beta-HSD1 expression in the fetal membranes is unknown. In this study, 11beta-HSD1 and glucocorticoid receptor (GR) were coexpressed in the chorionic trophoblast. Radiometric conversion assay and Northern blot analysis revealed that both 11beta-HSD1 reductase activity and mRNA levels were increased by dexamethasone (1 microM, 0.1 microM) in the cultured chorionic trophoblast, and the effects were blocked by GR antagonist RU486 (1 microM). Prior induction of 11beta-HSD1 by dexamethasone potentiated the subsequent stimulation of prostaglandin H synthetase 2 expression and secretion of prostaglandin E(2) by cortisone in the chorionic trophoblast. There is colocalization of 11beta-HSD1 and GR in the chorionic trophoblast. By binding to GR, glucocorticoids induce the expression of 11beta-HSD1 by a possible intracrine mechanism, thereby amplifying the actions of glucocorticoids on prostaglandin production in the fetal membranes. This cascade of events initiated by glucocorticoids may play an important role in the positive feed-forward mechanisms of labor.
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PMID:Intracrine induction of 11beta-hydroxysteroid dehydrogenase type 1 expression by glucocorticoid potentiates prostaglandin production in the human chorionic trophoblast. 1239 Aug 75


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