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)

Recently, the structure of two genes encoding isoenzymes responsible for 3 beta-hydroxysteroid dehydrogenase/delta 5-delta 4-isomerase (3 beta HSD) activity in the human was elucidated. This activity is an essential step in the biosynthesis of all classes of steroid hormones. In the classic severe form of 3 beta HSD deficiency, patients present with adrenal insufficiency, various degrees of salt loss, and incomplete masculinization in males. Here we report the characterization of the molecular basis of congenital adrenal hyperplasia due to 3 beta HSD deficiency in a male pseudohermaphrodite born from consanguineous parents and having no clinical salt loss. To analyze the structure of the type I and II 3 beta HSD genes of the patient, DNA fragments, generated by polymerase chain reaction amplification of the four exons and the exon-intron boundaries of these genes, were directly sequenced. The patients carried a homozygous missense mutation converting Asn100 to Ser in exon 3 of his type II 3 beta HSD gene. His parents were heterozygous for the same point mutation. The absence of clinical salt loss associated with a male pseudohermaphroditism suggested that 3 beta HSD activity was impaired to different levels in the testes and adrenal. To elucidate whether this N100S missense mutation affected preferentially a steroidogenic pathway, enzymatic activity was analyzed by in vitro analysis of mutant recombinant enzyme generated by site-directed mutagenesis after its transient expression in COS-1 cells. Using homogenates from transfected cells, the N100S 3 beta HSD enzyme showed a Km value for pregnenolone of 25 +/- 3 mumol/L compared with 3.5 +/- 0.2 mumol/L for the normal human type II 3 beta HSD enzyme. Similar results were obtained using dehydroepiandrosterone as substrate. In addition to decreasing apparent affinity, the N100S mutation decreased the relative specific activity (Vmax), leading to a relative specificity (relative Vmax/Km) 2.7% and 11% that of normal type II 3 beta HSD using pregnenolone or dehydroepiandrosterone as substrate, respectively. Moreover, the mutant N100S protein had an apparent decreased affinity for NAD+, with a Km value of 650 +/- 66 mumol/L compared with 20 +/- 2 mumol/L for normal type II 3 beta HSD. Except for the hypothetical effect of local factors, these findings suggest that a very weak residual activity of the normal type II 3 beta HSD enzyme could prevent salt loss, but it was insufficient for normal male sex differentiation.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Nonsalt-losing male pseudohermaphroditism due to the novel homozygous N100S mutation in the type II 3 beta-hydroxysteroid dehydrogenase gene. 760 65

11 beta-hydroxysteroid dehydrogenase (11-HSD) activity allows aldosterone occupancy of mineralocorticoid receptors by inactivating endogenous glucocorticoids. The expression of the 11-HSD2 gene, a low Km, NAD+ dependent species of 11-HSD, was found in several discrete areas of the rat brain by in situ hybridization. Cells strongly positive for 11-HSD2 mRNA were found in the commissural portion of the nucleus tractus solitarius, subcommissural organ and ventrolateral ventromedial hypothalamus. Scattered labeled cells were also seen in the medial vestibular nucleus. The expression of 11-HSD2 mRNA in the brain is quite distinct from that of 11-HSD1 mRNA and allows for diverse roles in modulating corticosteroid receptor involvement in control of salt appetite, blood pressure and the hypothalamo-pituitary-adrenal axis.
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PMID:Hybridization histochemical localization of 11 beta-hydroxysteroid dehydrogenase type 2 in rat brain. 766 91

We report mutations of the type II 3 beta-hydroxysteroid dehydrogenase (3 beta HSD) gene in two siblings, male and female, with congenital adrenal hyperplasia caused by classical nonsalt-losing 3 beta HSD deficiency. During childhood, the male sibling, born with ambiguous genitalia, and the female sibling, born with normal genitalia, both manifested symptoms of mild androgen excess; both apparently had normal zona glomerulosa function. Gonadal dynamic study at puberty showed the presence of partial gonadal 3 beta HSD deficiency in both siblings despite their spontaneous pubertal maturation. The 5'-region as well as exons I-II, III, and IV and portions of the adjacent introns of the type II 3 beta HSD gene were amplified by polymerase chain reaction and sequenced. In both siblings and their mother, an identical single nucleotide substitution mutation in intron III, six bases up-stream from exon IV, was identified in one allele. This mutation, G to A at nucleotide 6651, may create a new splicing junction and affect the normal splicing of the messenger ribonucleic acid. In the other allele of both siblings, a missense mutation from GGG (Gly) to AGG (Arg) at codon 129 (G129R) in exon IV was found. We assessed the effect of the G129R missense mutation on enzymatic activity by in vitro analysis of the mutant recombinant enzyme generated by site-directed mutagenesis after its transient expression in COS-1 cells. Using homogenates from transfected cells, the G129R 3 beta HSD enzyme showed a Km value for pregnenolone of 10 +/- 2 mumol/L compared with 1.00 +/- 0.03 mumol/L for the wild-type type II 3 beta HSD enzyme. When dehydroepiandrosterone was used as substrate, the Km value for G129R3 beta HSD was 14 +/- 2 mumol/L compared with 2.1 +/- 0.2 mumol/L for the wild-type II 3 beta HSD enzyme. In addition to an apparent decrease in affinity, the G129R mutation caused a marked decrease in the apparent relative specific activity, thus leading to apparent relative specific efficiencies (relative specific activity/Km) of 2.0% and 4.7% that of the normal type II 3 beta HSD using pregnenolone or dehydroepiandrosterone as substrate, respectively. It appears likely that this low level of activity is sufficient to prevent salt loss, but it is also possible that part of the enzymatic activity comes from the putative remaining percentage of correctly spliced n6651 allele in these patients.
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PMID:Molecular basis of congenital adrenal hyperplasia in two siblings with classical nonsalt-losing 3 beta-hydroxysteroid dehydrogenase deficiency. 796 68

Nonclassical 3 beta-hydroxysteroid dehydrogenase/delta 5-delta 4-isomerase deficiency (NC3 beta HSDD) has been diagnosed in hyperandrogenic women with an increasing frequency during the last 14 yr. Fifteen menarcheal women with androgen excess syndrome, diagnosed with NC3 beta HSDD previously were restudied, in 12 after discontinuation of glucocorticoid treatment, in 2 patients never treated with glucocorticoids, and in 1 both before and after glucocorticoid therapy. Each of the 15 patients underwent ACTH stimulation testing, in some cases on multiple occasions. Although some (very few) patients seem to have improved with time, others remained the same or got worse. Molecular DNA analysis was also performed in 6 of the patients, using the strategy successfully used to detect point mutations in the type II 3 beta-hydroxysteroid dehydrogenase (3 beta HSD) gene, which are responsible for classical 3 beta HSD deficiency. This strategy consists of the direct sequencing of polymerase chain reaction-amplified DNA fragments corresponding to the complete coding sequence and all intron-exon junctions and to the 5'- and 3'-noncoding region of this gene. We were unable to demonstrate any mutation of the type II 3 beta HSD gene in these 6 patients. To gain additional information about potential mutations, direct sequencing of the type I 3 beta HSD gene was also performed using this same strategy, and no mutations were found. The present study strongly suggests that unlike the salt-losing and nonsalt-losing forms of classical 3 beta HSD deficiency, NC3 beta HSDD is not due to a mutant type II 3 beta HSD enzyme. However, the possibility remains of a mutation(s) in the unsequenced regions of the type II 3 beta HSD gene or elsewhere, such as in a gene for modulatory protein, playing a specific role in the expression of the type II 3 beta HSD gene. On the other hand, knowing the multiple hormonal controls to which 3 beta HSD activity is subject, it cannot be excluded that at least in some cases, NC3 beta HSDD may be an acquired defect, the result of endogenous or environmental factors.
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PMID:No evidence of mutations in the genes for type I and type II 3 beta-hydroxysteroid dehydrogenase (3 beta HSD) in nonclassical 3 beta HSD deficiency. 798 89

There is little information about the plasma concentrations of 3 beta-hydroxy-delta 5-steroids (delta 5-steroids) in untreated patients with congenital adrenal hyperplasia due to 21-hydroxylase deficiency. To further study the delta 5 pathway, we measured plasma levels of delta 5- and delta 4-steroids in 21 adult patients with different degrees of 21-hydroxylase deficiency (11 salt-wasters, 5 simple virilizers, and 5 patients with the nonclassical form of the disease). In all patients, investigations were performed after withdrawal of steroid treatment for at least 10 days. In addition, catheterization of gonadal and adrenal veins was performed in two salt-wasting male patients displaying bilateral testicular tumors to study adrenal secretion of delta 5- and delta 4-steroids. In one of them, surgical resection of the intratesticular adrenal rests gave the opportunity to measure 3 beta-hydroxysteroid dehydrogenase (3 beta HSD) activity. In all untreated patients, an increase in plasma delta 4-steroids was observed. In contrast, although plasma levels of dehydroepiandrosterone (DHEA) and dehydroepiandrosterone sulfate (DHEAS) were not significantly modified in simple virilizers, a paradoxical decrease in all delta 5-steroids was observed in salt-wasters. Catheterization of the adrenal veins confirmed the decrease in delta 5-steroids, particularly DHEA and DHEAS. The androstenedione/DHEA ratio was increased in all patients proportionally to the severity of the disease, suggesting an increase in adrenal 3 beta HSD. In vitro analysis of 3 beta HSD activity showed a 4-fold increase in intratesticular adrenal tissue compared to that in normal adrenals. A positive correlation between the androstenedione/DHEA ratio and plasma ACTH levels was observed, suggesting a long term stimulatory effect of ACTH on 3 beta HSD. Angiotensin-II could have an additive effect on ACTH-induced 3 beta HSD activity.
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PMID:Plasma 3 beta-hydroxy-delta 5-steroids in patients with congenital adrenal hyperplasia due to 21-hydroxylase deficiency. 810 15

11 beta-Hydroxysteroid dehydrogenase (11 beta-HSD) modulates the access of corticosteroids to their receptors and plays an important role in controlling blood pressure. We determined 11 beta-HSD activity and mRNA levels in the mesenteric arteries of genetically hypertensive rats, the Dahl salt-sensitive hypertensive rat, and compared them with Dahl salt-resistant and Sprague-Dawley rats. 11 beta-HSD activity was expressed as the percent conversion of [3H]corticosterone to [3H]11-dehydrocorticosterone. 11 beta-HSD activity was significantly decreased in the mesenteric arteries of 8-week-old Dahl salt-sensitive hypertensive rats (11.4 +/- 1.4%) compared with Dahl salt-resistant rats (17.4 +/- 1.4%) or Sprague-Dawley rats (18.0 +/- 1.5%) of the same age (P < .05). There were no significant differences in 11 beta-HSD activity between 4-week-old Dahl salt-sensitive hypertensive and Dahl salt-resistant rats of the same age (15.3 +/- 1.3% and 15.1 +/- 1.9%, respectively). The concentration of 11 beta-HSD mRNA in the mesenteric arteries of 8-week-old Dahl salt-sensitive hypertensive rats was significantly lower than in Dahl salt-resistant or Sprague-Dawley rats of the same age (P < .05). There were no significant differences in the concentration of 11 beta-HSD mRNA in the mesenteric arteries of 4-week-old Dahl salt-sensitive hypertensive rats, Dahl salt-resistant rats, and Sprague-Dawley rats. These results indicate that 11 beta-HSD in the vascular wall may play a role in the pathogenesis of hypertension in this rat model.
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PMID:Gene expression of 11 beta-hydroxysteroid dehydrogenase in the mesenteric arteries of genetically hypertensive rats. 817 64

11 beta-Hydroxysteroid dehydrogenase (11 beta-HSD) activity in mesenteric arteries of 4-week- and 8-week-old Dahl rats was determined to evaluate the relationship between glucocorticoids and norepinephrine in hypertension, 11 beta-HSD activity (expressed as the percentage conversion of 3H-corticosterone (B) to 3H-11-dehydrocorticosterone (A)) significantly decreased in 8-week-old Dahl salt-sensitive (DS) rats (11.4 +/- 1.4%) compared with Dahl salt-resistant (DR) rats (15.3 +/- 0.3%) (p < 0.05) when each group was fed a high-sodium chow (7%) for 4 weeks. There were no significant differences in 11 beta-HSD activity in the 4-week-old DS and DR rats. The enhanced response of mesenteric arteries to norepinephrine was observed only in 8-week-old DS rats. Our results suggest that a decreased 11 beta-HSD activity in the vascular walls contributes to the increased response of norepinephrine by local increment of glucocorticoids in DS hypertensive rats.
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PMID:Decreased activity of 11 beta-hydroxysteroid dehydrogenase in mesenteric arteries of Dahl salt-sensitive rats. 819 6

The isoenzymes of the 3 beta-hydroxysteroid dehydrogenase/5-ene-4-ene-isomerase (3 beta-HSD) gene family catalyse the transformation of all 5-ene-3 beta-hydroxysteroids into the corresponding 4-ene-3-keto-steroids and are responsible for the interconversion of 3 beta-hydroxy- and 3-keto-5 alpha-androstane steroids. The two human 3 beta-HSD genes and the three related pseudogenes are located on the chromosome 1p13.1 region, close to the centromeric marker D1Z5. The 3 beta-HSD isoenzymes prefer NAD+ to NADP+ as cofactor with the exception of the rat liver type III and mouse kidney type IV, which both prefer NADPH as cofactor for their specific 3-ketosteroid reductase activity due to the presence of Tyr36 in the rat type III and of Phe36 in mouse type IV enzymes instead of Asp36 found in other 3 beta-HSD isoenzymes. The rat types I and IV, bovine and guinea pig 3 beta-HSD proteins possess an intrinsic 17 beta-HSD activity specific to 5 alpha-androstane 17 beta-ol steroids, thus suggesting that such "secondary" activity is specifically responsible for controlling the bioavailability of the active androgen DHT. To elucidate the molecular basis of classical form of 3 beta-HSD deficiency, the structures of the types I and II 3 beta-HSD genes in 12 male pseudohermaphrodite 3 beta-HSD deficient patients as well as in four female patients were analyzed. The 14 different point mutations characterized were all detected in the type II 3 beta-HSD gene, which is the gene predominantly expressed in the adrenals and gonads, while no mutation was detected in the type I 3 beta-HSD gene predominantly expressed in the placenta and peripheral tissues. The mutant type II 3 beta-HSD enzymes carrying mutations detected in patients affected by the salt-losing form exhibit no detectable activity in intact transfected cells, at the exception of L108W and P186L proteins, which have some residual activity (approximately 1%). Mutations found in nonsalt-loser patients have some residual activity ranging from approximately 1 to approximately 10% compared to the wild-type enzyme. Characterization of mutant proteins provides unique information on the structure-function relationships of the 3 beta-HSD superfamily.
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PMID:Structure-function relationships and molecular genetics of the 3 beta-hydroxysteroid dehydrogenase gene family. 854 74

1. A patient with severe hypertension was found to have mildly impaired 11 beta-hydroxysteroid dehydrogenase (11 beta-HSD) activity on the basis of urinary steroid metabolite ratios, low plasma aldosterone, angiotensin II and renin levels and marginally low levels of plasma potassium. 2. The patient also had a compulsively high salt intake. 3. We tested the hypothesis that high salt intake may affect 11 beta-HSD activity. 4. High salt intake in normal subjects did not significantly alter either blood pressure or 11 beta-HSD activity. 5. We suggest that the potentially small hypertensive effect of the partial enzyme deficiency in our patient, also reported in patients with essential hypertension, has been markedly amplified by the very high salt intake.
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PMID:Sodium status, corticosteroid metabolism and blood pressure in normal human subjects and in a patient with abnormal salt appetite. 871 74

Rat liver 3 alpha-hydroxysteroid/dihydrodiol dehydrogenase (3 alpha-HSD) inactivates circulating steroid hormones and is involved in polycyclic aromatic hydrocarbon (PAH) carcinogenesis. It is the only HSD of known structure in the aldo-keto reductase (AKR) superfamily and may provide a paradigm for other mammalian HSDs in this family. The structure of the 3 alpha-HSD.NADP+ binary complex has been determined at 2.7 A resolution and refined to a crystallographic R-factor of 23.4% with good geometry. The model is similar to other binary complexes in the AKR superfamily in that NADP+ binds at the C-terminal end of an alpha/beta barrel. However, it is unique in that NADP+ is bound in two alternate conformations, probably because of the lack of a salt-linked "safety belt" over the pyrophosphate bridge. The structure supports a previously proposed catalytic mechanism for carbonyl reduction in which Tyr 55 is the general acid, and its effective pKa is lowered by the adjacent Lys 84. We present evidence that the structurally distinct short-chain dehydrogenase/reductase (SDR) superfamily may have convergently evolved a similar catalytic mechanism. Insight into substrate binding is offered by a crystal packing contact in which a neighboring molecule inserts a tryptophan residue (Trp 227) into an apolar cleft in 3 alpha-HSD. This cleft is proximal to the bound NADP+ cofactor and contains a surface of apolar residues (Leu 54, Trp 86, Leu 122, Phe 128, Phe 129, Leu 137, Phe 139), making it a likely candidate for the substrate-binding site. Thus, in forming this crystal contact, Trp 227 may mimic a portion of a bound steroid. In addition, we propose that a water molecule in the active site indicates the position of the hydroxyl oxygen in a 3 alpha-hydroxysteroid substrate. Knowledge of the position of this water molecule, combined with the stereochemistry of hydride transfer, suggests that the alpha face of a bound steroid will be oriented toward the side of the apolar cleft containing Trp 86.
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PMID:Structure of 3 alpha-hydroxysteroid/dihydrodiol dehydrogenase complexed with NADP+. 871 59


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