Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The 11beta-hydroxysteroid dehydrogenase type II enzyme (11betaHSD2) endows specificity on the mineralocorticoid receptor by metabolising glucocorticoids. Sequence comparisons with other microsomal proteins showed the strongly preferred topology of a lumenal pentapeptide followed by three transmembrane helices with residues beyond Ala73 on the cytoplasmic side of the membrane, suggesting that 11betaHSD2 is anchored to the endoplasmic reticulum by the N-terminal region. However, deletion of the N-terminus (11betaHSD2 deltaN) and expression of the construct in mammalian cells showed that the enzyme remained bound to the microsomal fraction, indicating that other regions are also involved in membrane anchoring. Crosslinking studies and nonreducing SDS-PAGE demonstrated that 11betaHSD2 is a non-covalently linked dimer. Deletion of the non-conserved C-terminal region (11betaHSD2 deltaC) resulted in an enzyme with a Km of 215 nM for cortisol in whole cell assays, while 11betaHSD2 and 11betaHSD2 deltaN displayed a Km of 62 and 74 nM, respectively. In homogenates 11betaHSD2 and 11betaHSD2 deltaC displayed maximal activity at 140 mM NaCl or KCl, but showed a marked decrease in enzyme activity with increasing salt. 11BetaHSD2 was more stable than 11betaHSD2 deltaC in the presence of NaSCN, suggesting that the C-terminal region plays a role in enzyme stability. There was no detectable activity in homogenates containing 11betaHSD2 deltaN, while 11betaHSD2 deltaC and 11betaHSD2 displayed a Km of 135 and 46 nM, respectively. Although 11betaHSD2 is conventionally considered a unidirectional dehydrogenase all constructs converted 11-dehydrodexamethasone to dexamethasone in whole cell assays, providing an explanation for the potency of the synthetic glucocorticoid in the face of a powerful inactivator of natural glucocorticoids.
Mol Cell Endocrinol 1997 Aug 08
PMID:Truncation of the N- and C-terminal regions of the human 11beta-hydroxysteroid dehydrogenase type 2 enzyme and effects on solubility and bidirectional enzyme activity. 929 76

To date, two isoforms of 11beta-hydroxysteroid dehydrogenase (11betaHSD) have been characterized: a low affinity, NADP+-dependent isoform (11betaHSD1) and a high affinity, NAD+-dependent isoform which metabolizes dexamethasone and is inhibited by cortisone (11betaHSD2). Having previously reported a relationship between ovarian 11betaHSD activities and conception in women undergoing in vitro fertilization (IVF-ET), the objective of the present study was to identify which isoforms of 11betaHSD metabolize glucocorticoids in cultures of human granulosa-lutein cells. In both intact cells and cell homogenates, two distinct 11betaHSD activities were identified with differing affinities for cortisol (Km = 490 nM and 2.6 microM). Even at low concentrations, cortisol oxidation was preferentially supported by NADP+ and was independent of NAD+. Although inhibited by the hemisuccinate ester of glycyrrhetinic acid, carbenoxolone, the predominant 11betaHSD activity in intact cells was resistant to end-product inhibition. Intact cells were also able to reduce [3H]cortisone (Km = 190 nM) but did not metabolize [3H]dexamethasone. 11BetaHSD1 mRNA was expressed in 23 of 28 cell cultures whereas 11betaHSD2 mRNA was not expressed in any of the 22 independent cultures studied by reverse transcriptase-polymerase chain reaction (RT-PCR). We conclude that human granulosa-lutein cells express both type 11betaHSD and a novel isoform of this enzyme. While the low affinity 11beta-dehydrogenase and 11-ketosteroid reductase activities exhibit properties consistent with 11betaHSD1, the high affinity 11beta-dehydrogenase differs from 11betaHSD2 in that it is NADP+-dependent, does not metabolize dexamethasone and is resistant to end-product inhibition.
Mol Cell Endocrinol 1997 Sep 19
PMID:Isoforms of 11beta-hydroxysteroid dehydrogenase in human granulosa-lutein cells. 932 45

We prepared a monoclonal antibody (mAb) A-I4-48 to HDL apolipoprotein A-I with the ultimate goals of expressing the valuable immunodiagnostic single-chain Fv (scFv) in Escherichia coli. The binding specificity of mAb A-I4-48 was determined by ELISA and Western blot analysis. The dissociation constant (Kd) of antigen-antibody complex obtained by ELISA was 8.33 x 10(-8) M. Poly(A)+ RNA was prepared from the hybridoma cell line secreting mAb A-I4-48 and used as a template for cDNA synthesis and cloning. The nucleotide sequence analyses revealed that the variable regions of the heavy- and light-chains were members of mouse heavy-chain subgroup IIA and kappa light-chain subgroup II, respectively. Comparison of the nucleotide sequences with mouse immunoglobulin genes in the GenBank data base showed that the cDNAs have not been previously reported.
Res Commun Mol Pathol Pharmacol 1997 Sep
PMID:Cloning of cDNAs coding for heavy- and light-chain variable regions of a murine monoclonal antibody with specificity for human plasma apolipoprotein A-I. 938 87

The present study was designed to examine the effects of metyrapone in vitro on the activities of 11beta-hydroxysteroid dehydrogenase (11beta-HSD) types 1 and 2, the two intracellular enzymes responsible for the metabolism of glucocorticoids. Enzymatic activities of 11beta-HSD1 and 2 were determined by a radiometric conversion assay using cortisol and cortisone as physiological substrates. The enzyme activity assays were carried out in the absence and presence of metyrapone using sheep liver and kidney microsomes as the source of 11beta-HSD1 and 2, respectively. It was found that metyrapone inhibited the reductase activity of 11beta-HSD1 in a dose-dependent manner with an apparent Ki of 30 microM. Moreover, this inhibition was competitive because the Km for cortisone was increased in the presence of metyrapone. In contrast, metyrapone showed biphasic effects on the dehydrogenase activity of 11beta-HSD1, in that it increased the activity at concentrations lower than 100 microM but decreased it at higher concentrations. However, under similar conditions, metyrapone had little effect on the unidirectional dehydrogenase activity of 11beta-HSD2. In conclusion, the present results provide the first direct evidence that metyrapone is a competitive inhibitor of 11beta-HSD1 reductase, and that it also exerts biphasic effects on 11beta-HSD1 dehydrogenase activity. These findings indicate that metyrapone influences peripheral glucocorticoid metabolism through its regulation of 11beta-HSD1 activity, in addition to its classic inhibitory effects on adrenal steroid biosynthesis. It is therefore imperative that this novel extra-adrenal effect of metyrapone be considered when this drug is used in the diagnosis and treatment of adrenocorticoid-related diseases.
J Steroid Biochem Mol Biol 1997 Jun
PMID:Metyrapone is a competitive inhibitor of 11beta-hydroxysteroid dehydrogenase type 1 reductase. 939 54

It is well established that there are interactions between the immune and reproductive systems. The ovary contains indigenous macrophages, as well as other classes of leukocytes in smaller numbers. Cytokines secreted by these cells have been shown to have the ability to regulate ovarian steroidogenesis. In the present study, the effect of leukocytes on 11beta-hydroxysteroid dehydrogenase (11beta-HSD) in human granulosa-lutein cells was examined. In addition, individual cytokines were also tested for their ability to regulate this enzyme. The follicular aspirates of patients undergoing IVF treatment were used as a source of granulosa cells. Cells isolated from these aspirates were found to contain between 15 and 60% leukocytes as assessed by flow cytometry (FACS). Leukocytes were removed from the sample preparations by the use of immunomagnetic beads coated with CD45 antibody, which recognises a surface antigen on all classes of leukocyte. Removal of leukocytes significantly decreased the 11beta-HSD activity in the granulosa cells, assayed after 3 days of culture, from 7.3 (2-20) to 3.5 (1-10) pmol cortisone formed/50000 cells/4 h (medians and ranges, n = 15). Addition of IL-5 and IL-6 significantly increased the 11beta-HSD activity in granulosa cell cultures both in the presence and absence of leukocytes. Addition of IL-4 and IFN-gamma increased 11beta-HSD activity only in the leukocyte-depleted granulosa cell cultures, whereas IL-2 had no effect on either of the cultures. The data suggests that leukocytes interact with the ovarian cells through cytokine secretion and/or cell-cell contact to increase the 11beta-HSD activity in human granulosa cells.
Mol Cell Endocrinol 1997 Oct 20
PMID:Leukocytes modulate 11beta-hydroxysteroid dehydrogenase (11beta-HSD) activity in human granulosa-lutein cell cultures. 940 53

We have previously reported the placental metabolism of prednisolone to prednisone, 20alpha- and beta-dihydroprednisone and 20beta-dihydroprednisolone. In this study, the disposition of cortisol was investigated in vitro in the dual perfused, isolated human placental lobule after the addition of cortisol (1.2 micromol, n = 3 and 12 micromol, n = 4) to the maternal compartment. Analysis of 5 h maternal and fetal perfusate samples by high performance liquid chromatography-electrospray-tandem mass spectrometry (HPLC-ESI-MS/MS) revealed that cortisol was mainly metabolized to cortisone, but a significant production of 20alpha-dihydrocortisone, 20beta-dihydrocortisone, 20alpha-dihydrocortisol and 20beta-dihydrocortisol was also detected. Saturability of metabolism but not transfer was demonstrated. Metabolism was eliminated by co-perfusion with the potent 11beta-hydroxysteroid dehydrogenase (11beta-HSD) enzyme inhibitor 18beta-glycyrrhetinic acid (GA). The disposition of GA was analysed using HPLC-atmospheric pressure chemical ionisation-MS/MS (HPLC-APCI-MS/MS). GA was found to transfer from the maternal to the fetal circulations without detectable metabolism during 6 h of perfusion.
J Steroid Biochem Mol Biol 1997 Jul
PMID:Cortisol metabolism and its inhibition by glycyrrhetinic acid in the isolated perfused human placental lobule. 940 88

Progesterone biotransformation was examined in relation to hydroxylating and dehydrogenating enzymes of Cochliobolus lunatus. 11beta-hydroxysteroid dehydrogenase activity (11beta-HSD) was located in cytosolic fraction and was NADP-dependent, inducible by progesterone and apparently uni-directional. Several inhibitors of 11beta-hydroxysteroid dehydrogenase were tested; furosemide, glycyrrhizic-acid and carbenoxolone did not influence the dehydrogenation of 11beta-hydroxy-4-pregnene-3,20-dione to 4-pregnene-3,11,20-trione, although grapefruit juice significantly reduced the rate of progesterone hydroxylation.
J Steroid Biochem Mol Biol
PMID:11Beta-hydroxysteroid dehydrogenase activity in progesterone biotransformation by the filamentous fungus Cochliobolus lunatus. 945 1

Various researchers have observed a higher risk for atherosclerosis when body iron concentration is elevated. The exact mechanism, however, is not known, but probably occurs catalytically via iron. Whether or not body iron concentration has an effect on plasma lipoproteins is also unknown. The aim of this study was to investigate whether or not ferritin concentration within the normal range correlate with LDL-cholesterol (an atherosclerotic risk factor), HDL-cholesterol, apoB, triglyceride and the mobility of LDL particles. Blood was drawn from healthy female volunteers and the above parameters measured. LDL-cholesterol, apoB and the electrophoretic mobility of LDL particles were elevated with increasing ferritin concentrations. Both modified or oxidized LDL and elevated LDL concentration are regarded as risks for atherosclerosis and ischemic heart disease, suggesting that higher body iron is important in this process.
Res Commun Mol Pathol Pharmacol 1997 Nov
PMID:Influence of ferritin levels on LDL cholesterol concentration in women. 946 28

The presence of 11beta-hydroxysteroid dehydrogenase (11beta-HSD; EC1.1.1.146), the enzyme responsible for the interconversion of cortisol and cortisone, in granulosa-lutein (GL) cells is associated with a poor outcome in in-vitro fertilization (IVF). We have developed a simple method of assessing the reductase component of 11beta-HSD in these cells which is sufficiently rapid to provide data on the enzyme's activity prior to embryo replacement. Cells were pooled from follicular aspirates and challenged with cortisone within 2 h of aspiration. Cortisol secretion was then measured by radioimmunoassay. Conversion of cortisone to cortisol was linear for up to 3 h and was completely inhibited by glycyrrhetinic acid, a specific 11beta-HSD inhibitor. Initial velocity rates were determined for eight cortisone concentrations (range 0.1-8 micromol/l), and the apparent Km calculated (1.6 +/- 0.4 micromol/l). There was no evidence of substrate/product inhibition and conversion of cortisone to cortisol was <2% in all experiments. In subsequent work, cells were challenged with cortisone (6 micromol/l) for 2 h. Cells challenged for 2 h immediately following purification from follicular aspirates produced varying amounts of cortisol (range 25-150 nmol/pooled follicles from each patient, n = 10 patients), while basal outputs were <6 nmol/l. Enzyme activity was also examined in cells on a per follicle basis from individual patients and found to vary considerably (e.g. 19, 53 and 36 nmol/l cortisol/1000 cells, three follicles). Having established the method for assessing 11beta-reductase activity within GL cells, we performed a small prospective study on a series of 20 patients examining the enzyme activity within 110 individual follicles. 11Beta-reductase activity varied greatly from patient to patient and from follicle to follicle ranging from <0.024-0.57 nmol cortisol/microg DNA but at present low patient numbers preclude a meaningful correlation between enzyme activity and pregnancy rate. In summary, we have developed a simple, rapid (<8 h) assay for detecting the reductase activity of 11beta-HSD in GL cells isolated from pooled or individual follicles. This procedure is sufficiently quick to aid in the choice of embryo for replacement.
Mol Hum Reprod 1998 Feb
PMID:A rapid method for the measurement of the oxoreductase activity of 11beta-hydroxysteroid dehydrogenase in granulosa-lutein cells from patients undergoing in-vitro fertilization. 954 72

High body iron and LDL-cholesterol concentrations, and antioxidant deficiency, are regarded as risk factors for ischemic heart disease. Iron is well known for causing oxidative damage and antioxidants for their beneficial effects on radical scavenging. It is, however, unknown whether or not dietary iron causes depletion of plasma antioxidants; causes lipid peroxidation; alters HDL- and LDL-cholesterol, and triglyceride concentrations. Rats received diets differing only in iron concentration--15 mg/Kg, 35 mg/Kg, 150 mg/Kg or 300 mg/Kg diet. The second group of rats received antioxidants (alpha-tocopherol and beta-carotene) in their drinking water. Increasing dietary iron increased plasma lipid hydroperoxide and LDL-cholesterol concentrations, but did not affect HDL-cholesterol or triglyceride concentrations. It decreased antioxidants, alpha-tocopherol and retinol. Antioxidant supplementation inhibited the above changes.
Res Commun Mol Pathol Pharmacol 1998 May
PMID:Dietary iron elevates LDL-cholesterol and decreases plasma antioxidant levels: influence of antioxidants. 966 68


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