Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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 fetal zone of the human fetal adrenal (HFA) gland is established to have decreased 3 beta-hydroxysteroid dehydrogenase/delta 4-5 isomerase (3 beta HSD) activity compared to the neocortex or definitive zone. 3 beta HSD activity, however, can be induced in primary cell culture through treatment with ACTH. Therefore, the HFA with two distinct steroidogenic zones with differences in 3 beta HSD activity as well as the capacity to increase 3 beta HSD activity in response to ACTH provides an excellent model to study the regulation of this enzyme. The presence of 3 beta HSD in the fetal and neocortex zones of the HFA was examined using a polyclonal antibody raised against purified human placental microsomal 3 beta HSD. After homogenates of the fetal and neocortical zones of the HFA were electrophoresed on a sodium dodecyl sulfate-polyacrylamide gel and immunoblotted, the presence of the 3 beta HSD protein with a molecular size of 45 kDa could be demonstrated only in the neocortical zone. ACTH treatment (greater than 2 days) of fetal and neocortical zone explant cultures produced increases in cortisol secretion associated with the respective levels of immunodetectable 3 beta HSD protein. Cortisol and dehydroepiandrosterone sulfate were the respective principal steroid products of neocortical and fetal zone explants. After ACTH treatment, immunodetectable 3 beta HSD was induced to a greater magnitude in the neocortex. These findings provide evidence that the lack of 3 beta HSD activity in the fetal zone, previously considered to be the result of the presence of an endogenous inhibitor, is due to an absence of the protein in this portion of the gland. The lack or minimal expression of 3 beta HSD in the fetal zone of HFA may be due to the action (or lack thereof) of a tissue-specific factor regulating the synthesis of 3 beta HSD.
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PMID:3 beta-hydroxysteroid dehydrogenase/isomerase in the fetal zone and neocortex of the human fetal adrenal gland. 215 27

Cortisol production from cholesterol requires the activity of four steroid hydroxylases: cholesterol side chain cleavage cytochrome P-450 (P-450scc), 17 alpha-hydroxylase cytochrome P-450 (P-45017 alpha), 21-hydroxylase cytochrome P-450 (P-450C21) and 11 beta-hydroxylase cytochrome P-450 (P-45011 beta). We have previously shown that transformed, nonsteroidogenic COS 1 cells derived from monkey kidney are a useful system for expression of various forms of cytochrome P-450. The present study shows that COS 1 cell cultures multiply transfected with six plasmids containing all four steroid hydroxylases, 3 beta-hydroxysteroid dehydrogenase/delta 5----4-isomerase (3 beta HSD) and adrenodoxin produce cortisol and aldosterone when 22(R)-hydroxycholesterol is supplied to the system. When pregnenolone is used as substrate, various intermediate metabolites are detected at different time points further establishing the incorporation of complete functional steroidogenic pathways into the nonsteroidogenic cell cultures. Since the first and the last reactions in these pathways take place in the mitochondrion, the movement of various intermediate metabolites from mitochondrion to endoplasmic reticulum and back to mitochondrion occurs in and between COS 1 cells.
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PMID:Incorporation of steroidogenic pathways which produce cortisol and aldosterone from cholesterol into nonsteroidogenic cells. 229 41

Cortisol 11 beta-hydroxysteroid dehydrogenase (11 beta-HSD) deficiency was observed in four patients with apparent mineralocorticoid excess. The 11 beta-HSD deficiency was demonstrated by a markedly decreased urinary tetrahydrocortisone/tetrahydrocortisol (THE/THF) ratio (less than 1 in normal children) during infusion of ACTH and administration of hydrocortisone. We propose that in these patients the 11 beta-HSD deficiency impairs the metabolism of cortisol to cortisone, resulting in a prolonged cortisol half-life, suppression of ACTH, and normal serum cortisol. The 11 beta-HSD deficiency protects the patient from adrenal insufficiency despite the low cortisol secretion; the prolonged half-life of cortisol may contribute to the hypertension and hyporeninemia observed in this disorder. Continuous intravenous hydrocortisone administration resulted in increased blood pressure and decreased serum potassium. Addition of spironolactone during continued administration of 20 mg per day of hydrocortisone resulted in a decrease in blood pressure and a rise in serum potassium. These studies suggest that an abnormality in cortisol action or metabolism results in cortisol behaving as a potent mineralocorticoid. These findings may account for this syndrome of apparent mineralocorticoid excess.
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PMID:Apparent mineralocorticoid excess causing hypertension and hypokalemia in children. 346 39

Cortisol:cortisone interconversion was studied in human decidua obtained from three groups of patients at term (37-42 weeks): before the onset of labour (at elective Caesarean section), after labour of spontaneous onset, and after labour of induced onset. When intact tissue was incubated with [3H]cortisol or [3H]cortisone in phosphate buffer without added substrate or cofactors, cortisone to cortisol was the dominant conversion. However, when damaged cells or tissue homogenates were used in the same conditions, the dominant direction of the reaction was reversed, with a large increase in oxidative (cortisol to cortisone) activity. Cortisol:cortisone interconversion was similar in the three groups of samples using either intact tissue or homogenates, as was the total 11 beta-hydroxysteroid dehydrogenase (11 beta-HSD) activity measured in tissue homogenates in the presence of added substrate (cortisol or cortisone) and cofactors (NADP+ or NADPH). Endogenous cortisol concentrations in decidua were higher than those of cortisone, and the ratio of cortisol to cortisone was similar in the three groups. These findings suggest that there are no changes in human decidual 11 beta-HSD activity in relation to parturition. Specific activity of 11 beta-HSD decreased at high protein concentrations, suggesting the presence of some enzyme inhibitor(s) in homogenized decidual tissue.
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PMID:Cortisol:cortisone interconversion by human decidua in relation to parturition: effect of tissue manipulation on 11 beta-hydroxysteroid dehydrogenase activity. 695 60

In vivo electrogenic Na+ absorption (JeNa) in the human rectum is controlled by acute variation of aldosterone in nanomolar concentration range. In this study we report both the induction of JeNa in human rectum epithelium by nanomolar aldosterone added in vitro and the enzymatic control of glucocorticoid action on JeNa. JeNa was measured as amiloride-sensitive short-circuit current 8 h after addition of the respective steroid. Aldosterone (10 nM) caused JeNa of 5.7 +/- 1.4 mumol.h-1.cm-2. Cortisol in the same concentration did not induce significant JeNa. Because cortisol is readily inactivated by 11 beta-hydroxysteroid dehydrogenase (11 beta-HSD), the true mineralocorticoid activity of cortisol was evaluated after inhibition of 11 beta-HSD by carbenoxolone. Carbenoxolone alone did not exhibit mineralocorticoid activity. If cortisol (10 nM) was given together with carbenoxolone (1 microM), the resulting JeNa (4.5 +/- 0.4 mumol.h-1.cm-2) was not significantly different from that after 10 nM aldosterone, indicating equal intrinsic mineralocorticoid activity of cortisol and aldosterone. The same mechanisms were found in rat late distal colon. Kinetic data of carbenoxolone at 10 nM cortisol resulted in a Michaelis constant of 0.3 microMs, maximal absorption of 8.4 mumol.h-1.cm-2, and a Hill coefficient of 1.8. The effects of carbenoxolone and glycyrrhetinic acid did not differ. We conclude that JeNa is under complete control of mineralocorticoid action. "Spontaneous" JeNa in the beginning of the in vitro period can be explained by elevated steroid levels before tissue removal.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Enzyme- and mineralocorticoid receptor-controlled electrogenic Na+ absorption in human rectum in vitro. 763

Cortisol is converted to the inactive glucocorticoid, cortisone, in several tissues by 11 beta-hydroxysteroid dehydrogenase (11 beta HSD). We have recently measured 11 beta HSD activity in cultured human granulosa-lutein cells recovered from patients undergoing in-vitro fertilisation and embryo transfer (IVF-ET). We now report an association between the outcome of IVF-ET and 11 beta HSD activity in these cells. Of the 64 patients studied, 32 had detectable 11 beta HSD activity and none became pregnant; whereas 76% of the remaining "11 beta HSD-negative" patients achieved pregnancies. Hence 11 beta HSD activity may predict the outcome of IVF-ET.
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PMID:Ovarian 11 beta-hydroxysteroid dehydrogenase: potential predictor of conception by in-vitro fertilisation and embryo transfer. 810 24

Both cortisol and aldosterone bind to and activate the mineralocorticoid receptor. Cortisol concentrations are generally 100- to 200-fold higher than aldosterone concentrations, yet mineralocorticoids clearly exert effects different from glucocorticoids. One hypothesis is that 11 beta-hydroxysteroid dehydrogenase (11 beta-HSD), which converts cortisol to biologically inactive cortisone, protects the mineralocorticoid receptor from cortisol. The circulating concentrations of cortisol in the squirrel monkey are 20- to 50-fold higher than human cortisol concentrations, yet this animal has no evidence of glucocorticoid or mineralocorticoid excess. We used this experiment of nature to test the hypotheses that the known (hepatic) form of 11 beta-HSD protects renal mineralocorticoid receptors from the action of cortisol and that it modulates glucocorticoid concentrations in target tissues. Using a long oligonucleotide based on the rat sequence, we cloned the squirrel monkey 11 beta-HSD complementary DNA and gene. The encoded monkey amino acid sequence is 75% and 91% identical to the corresponding rat and human sequences, respectively. The tissue abundance of the messenger RNA for the monkey enzyme was similar to or less than that seen for the rat and human enzymes. Both the monkey and human 11 beta-HSD complementary DNAs were cloned into an expression vector and used to transfect cultures of Chinese hamster ovary cells. Both vectors were transcribed and translated into equivalent amounts of 11 beta-HSD enzyme. The monkey enzyme was slightly more efficient than the human enzyme in converting [3H]cortisol to cortisone, and estimates of the Michaelis-Menten constant and maximum velocity of both enzymes are similar. These data indicate that the abundance and activity of the hepatic form of 11 beta-HSD are insufficient to inactivate the very high concentrations of cortisol in the squirrel monkey, suggesting that this form of 11 beta-HSD does not defend the mineralocorticoid receptor or protect tissues from high cortisol concentrations. Rather, this enzyme appears to favor conversion of cortisone to cortisol, thus maximizing tissue concentrations of cortisol to overcome glucocorticoid resistance associated with a 50% reduction in glucococorticoid receptors.
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PMID:Structure and function of the hepatic form of 11 beta-hydroxysteroid dehydrogenase in the squirrel monkey, an animal model of glucocorticoid resistance. 831 83

Cortisol, produced by the primate fetal adrenal, regulates the maturation of organ systems necessary for extrauterine life. During most of primate pregnancy, however, the fetal adrenal lacks the enzyme 3 beta-hydroxysteroid dehydrogenase/isomerase (3 beta HSD), which is essential for cortisol synthesis. Therefore, we used immunohistochemistry and in situ hybridization techniques to investigate the developmental expression of 3 beta HSD in the fetal rhesus monkey adrenal from 109 days' gestation until term (165 +/- 5 days) and assessed the role of ACTH in the induction of its expression and localization. We also examined whether ACTH regulates the expression of two other steroidogenic enzymes, cytochrome P450 cholesterol side-chain cleavage (P450scc) and P450 17 alpha-hydroxylase, 17/20-lyase (P450c17), in the fetal rhesus monkey adrenal. To stimulate ACTH secretion from the fetal pituitary in vivo, we administered metyrapone to late gestation fetal rhesus monkeys for 3-7 days. Adrenals were collected from untreated fetuses at 109-125 days (n = 5), 130-148 days (n = 7), 155-172 days (n = 4), and after metyrapone treatment at 135-137 days (n = 4). The cortical width and total amount of 3 beta HSD staining were measured using an image analysis system. 3 beta HSD was localized primarily in the definitive zone cells of the adrenal from fetuses between 109-148 days, whereas at term (155-172 days), 3 beta HSD was localized in both definitive and transitional zone cells. The cortical width and total amount of 3 beta HSD staining in the adrenal increased significantly (P < 0.05) between 148 days (137 +/- 14 microns and 3,689 +/- 522 grains) and 155 days (315 +/- 61 microns and 7,321 +/- 2,008 grains). Interestingly, in metyrapone-treated fetuses at 135-137 days, 3 beta HSD messenger RNA (mRNA) and protein were localized extensively in both the definitive and transitional zones, a pattern seen only in term fetal adrenals in untreated animals. In addition, metyrapone treatment significantly (P < 0.05) increased cortical width (386 +/- 95 microns) and total 3 beta HSD immunostaining (29,063 +/- 13,692 grains) compared with age-matched controls. In contrast to 3 beta HSD, P450scc mRNA was detected in the definitive, transitional, and fetal zones, and its expression was not altered after metyrapone treatment. P450c17 mRNA was detected in the transitional and fetal zones, and the relative abundance was greater in the transitional zone. The relative abundance of P450c17 mRNA was increased in the fetal zone after metyrapone treatment. In summary, at term or after metyrapone treatment, expression of 3 beta HSD is induced in the transitional zone of the fetal rhesus monkey adrenal gland, an indication of functional maturation of the primate adrenal cortex. These data suggest that the ontogenetic increase in fetal pituitary ACTH secretion plays an important role in the induction of 3 beta HSD expression in the transitional zone.
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PMID:Functional maturation of the primate fetal adrenal in vivo. II. Ontogeny of corticosteroid synthesis is dependent upon specific zonal expression of 3 beta-hydroxysteroid dehydrogenase/isomerase. 889 68

In sheep, increased output of cortisol from the fetal adrenal gland is critical to organ maturation and parturition. Cortisol synthesis is determined in part by the activity of P450(C17) enzyme. We have used immunohistochemistry and Western immunoblotting to examine the distribution of P450(C17) in the ovine fetal adrenal during gestation, and after ACTH or dexamethasone administration to fetuses between Days 125 and 130. The patterns were compared with changes in 3beta-hydroxysteroid dehydrogenase (3beta-HSD) localisation and levels. Adrenal tissue was obtained from four fetuses at each of Days 63-65, 100, 125-130 and term (>140 days). Further animals were chronically catheterised and infused with ACTH, dexamethasone or saline for 96 h beginning on Day 125. Immunohistochemistry for P450(C17), 3beta-HSD, and phenylethanolamine-N-methyl transferase (PNMT) was conducted using standard techniques. At Day 63-65 of pregnancy immunoreactive (ir-)P450(C17) was present in cords of cells throughout the adrenal gland. Ir-P450(C17) was reduced or was undetectable at Day 100, but had increased by Day 125-130, and was present throughout the zona fasciculata of the adrenal cortex of term animals. An increase in P450(C17) protein was also seen between Day 100 and 125 by Western blotting, and after ACTH treatment. Dexamethasone administration led to a marked reduction in ir-P450(C17) levels. In contrast, ir-3beta-HSD was present in the fetal adrenal cortex between Day 100 and term, and was less affected by ACTH or dexamethasone treatment. We conclude that P450(C17) in the fetal sheep adrenal is responsive to regulation by ACTH, and that changes in its levels correlate with previously reported alterations in patterns of cortisol output by the fetal adrenal gland.
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PMID:Immunolocalisation of P450(C17) in the fetal sheep adrenal gland during gestation and in response to ACTH and glucocorticoid administration. 935 4

These studies investigated whether treatment with carbenoxolone (CBX), an inhibitor of 11 beta-hydroxysteroid dehydrogenase (11 beta-HSD), resulted in an enhanced mineralocorticoid response to endogenous or infused cortisol. In conscious sodium replete sheep with a parotid fistula, infusion of CBX (40 mg/h for 10 days) did not increase mean arterial pressure, or change sodium and potassium status or plasma renin concentration, but significantly increased the half-life of 1,2[3H] cortisol from 18.6 +/- 4.0 to 38.8 +/- 3.9 min (p < 0.05) and reduced the blood clearance rate of cortisol (BCR) from 31 +/- 3 to 15 +/- 4 L/h (p < 0.01). The reduction in cortisol BCR was associated with reduction in cortisol secretion rate from 433 +/- 116 to 181 +/- 79 nmol/h (p < 0.01). Cortisol (8 mg/h) for 5 days increased mean arterial pressure (from 83 +/- 2 to 101 +/- 5 mmHg, p < 0.001) and caused natriuresis, hypokalaemia and hyperglycaemia. These responses were unaltered when cortisol was infused from the fifth to the tenth day of CBX infusion. These findings suggest that in sheep, carbenoxolone is either a less potent inhibitor of 11 beta-HSD2 than in other species or 11 beta-HSD2 may not be the only mechanism, which determines the specificity of the MR.
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PMID:Carbenoxolone does not cause a syndrome of mineralocorticoid excess in sheep. 951 20


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