UNIPROT:P41181 - FACTA Search

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Query: UNIPROT:P41181 (collecting duct)
5,183 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The type 1 and type 2 isoforms of human 11 beta-hydroxysteroid dehydrogenase (11 beta-HSD) play a crucial role, respectively, in modulating glucocorticoid and mineralocorticoid hormone action. Deficiency of the 11 beta-HSD2 isoform, as described in the syndrome of apparent mineralocorticoid excess and following liquorice (glycyrrhetinic acid) or carbenoxolone ingestion, results in hypertension in which cortisol acts as a potent mineralocorticoid. Several studies have addressed the effects of progesterone, glycyrrhetinic acid, and their derivatives on 11 beta-HSD activity, but these were largely undertaken before the characterization of the 11 beta-HSD isoforms. The aim of this study was to evaluate the localization of 11 beta-HSD2 in human kidney and to study the effects of progesterone, glycyrrhetinic acid, and their related compounds on stable transfectants of the human 11 beta-HSD isoforms. Using an in-house sheep antibody against human 11 beta-HSD2, immunoperoxidase studies localized 11 beta-HSD2 to renal cortical and medullary collecting ducts. Glomeruli, vascular structures, loops of Henle, and proximal tubules were all negative. Confocal laser microscopy studies indicated both a cytoplasmic and nuclear localization for the enzyme within renal collecting ducts. The nuclear staining, which was intranuclear and was not associated with the nuclear membrane, accounted for 40% of the total cellular 11 beta-HSD2 immunoreactivity. Kinetic analysis of 11 beta-HSD activity in fetal kidney 293 cells stably transfected with h11 beta-HSD1/pcDNA3 or 11 beta-HSD2/pCR3, indicated, respectively, low-affinity dehydrogenase/oxoreductase activity (Km for F, 1.8 microM; Km for E, 270 nM) and high-affinity dehydrogenase activity (Km for F, 190 nM). The reductase activity of 11 beta-HSD1 was inhibited by 11 alpha-hydroxyprogesterone > carbenoxolone = glycyrrhetinic acid = progesterone > 11 beta-hydroxyprogesterone. The dehydrogenase activity of 11 beta-HSD2 was inhibited 11 alpha-hydroxyprogesterone = 11 beta-hydroxyprogesterone > glycyrrhetinic acid > carbenoxolone = progesterone. 11 beta-HSD2, expressed in the renal collecting duct, serves to protect the mineralocorticoid receptor (MR) in an autocrine fashion. The demonstration of a nuclear localization for what was thought to be principally a microsomal enzyme suggests that interaction between the MR and its ligand (either aldosterone or cortisol) may be a nuclear rather than a cytoplasmic event. The inhibitory effects of progesterone, glycyrrhetinic acid, and related compounds on 11 beta-HSD1 and 2 were similar, and it remains to be seen what implication these findings have for 11 beta-HSD1 action in tissues such as the liver and gonad and renal 11 beta-HSD2 activity in relation to sodium homeostasis and blood pressure control.
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PMID:Human 11 beta-hydroxysteroid dehydrogenase: studies on the stably transfected isoforms and localization of the type 2 isozyme within renal tissue. 902 19

Mineralocorticoid hormones regulate salt transport along the distal nephron by binding to intracellular receptors and activating gene transcription. Previous experiments showed that systemic aldosterone infusions stimulate thiazide-sensitive Na and Cl transport by distal convoluted tubule (DCT) cells; this effect could have been direct or secondary to systemic hormonal effects. Aldosterone target tissues express both mineralocorticoid receptors and the metabolic enzyme 11beta-hydroxysteroid dehydrogenase type 2. Mineralocorticoid receptors have been localized to the DCT in some experiments, but not in others. Expression of 11beta-hydroxysteroid dehydrogenase type 2 by DCT cells has not been investigated. The present experiments were designed to test the hypothesis that rat DCT cells are targets of aldosterone action. Patterns of mineralocorticoid receptor, 11beta-hydroxysteroid dehydrogenase, thiazide-sensitive Na-Cl cotransporter, and Na/Ca exchanger expression along the distal tubule were examined. A polyclonal antibody was generated to localize the thiazide-sensitive Na-Cl cotransporter. Thiazide-sensitive Na-Cl cotransporter and 11beta-hydroxysteroid dehydrogenase expression were examined using both in situ hybridization and immunocytochemistry; Na/Ca exchanger and mineralocorticoid receptor expression were examined by immunocytochemistry. The results indicate that 11beta-hydroxysteroid dehydrogenase is expressed by DCT cells, as well as connecting tubule cells and principal cells of the collecting duct; expression levels are low near the junction with the thick ascending limb and rise near the transition to the connecting tubule. Mineralocorticoid receptors are expressed by DCT cells, as well as along the thick ascending limb, connecting tubule, and collecting duct. The results indicate that components of the mineralocorticoid receptor system are expressed by DCT cells, suggesting that these cells are targets of aldosterone action.
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PMID:11Beta-hydroxysteroid dehydrogenase, mineralocorticoid receptor, and thiazide-sensitive Na-Cl cotransporter expression by distal tubules. 969 56

11Beta-hydroxysteroid dehydrogenase (11beta-HSD) is thought to confer aldosterone specificity to mineralocorticoid target cells by protecting the mineralocorticoid receptor (MR) from occupancy by endogenous glucocorticoids. In aldosterone target cells the type 2 11beta-HSD is present, which, in contrast to the type 1 11beta-HSD, has very high affinity for its substrate, is unidirectional and prefers NAD as cofactor. cDNAs encoding 11beta-HSD2 have been recently cloned from different species, and the cell-specific expression of its mRNA and protein were determined. 11Beta-HSD2 is expressed in every aldosterone target tissue. Northern analysis revealed that the rabbit 11beta-HSD2 is expressed at high levels in the renal collecting duct and at much lower levels in the colon. RT-PCR experiments demonstrated that 11beta-HSD2 mRNA is present only in aldosterone target cells within the kidney. We determined the subcellular localization of the rabbit 11beta-HSD2 using a chimera encoding 11beta-HSD2 and the green fluorescent protein (GFP). This construct was stably transfected into CHO and MDCK cells. The expressed 11beta-HSD2/GFP protein retained high enzymatic activity, and its characteristics were undistinguishable from those of the native enzyme. The intracellular localization of this protein was determined by fluorescence microscopy. 11Beta-HSD2-associated fluorescence was observed as a reticular network over the cytoplasm whereas the plasma membrane and the nucleus were negative, suggesting endoplasmic reticulum (ER) localization. Co-staining with markers for ER proteins, the Golgi membrane, mitochondria and nucleus confirmed that 11beta-HSD2 is localized exclusively to the ER. To determine what structural motifs are responsible for the ER localization, we generated deletion mutants missing the C-terminal 42 and 118 amino acids, and fused them to GFP. Similarly as with the intact 11beta-HSD2, these mutants localized exclusively to the ER. Both C-terminal deletion mutants completely lost dehydrogenase activity, independently whether activity was determined in intact cells or homogenates. These results indicate that 11beta-HSD2 has a novel ER retrieval signal which is not localized to the C-terminal region. In addition, the C-terminal 118 amino acids are essential for NAD-dependent 11beta-HSD activity.
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PMID:The role of 11beta-hydroxysteroid dehydrogenase in steroid hormone specificity. 969 85

11Beta-hydroxysteroid dehydrogenase type 2 (11betaHSD2) catalyzes the conversion of cortisol to biologically inactive cortisone and is thought to confer specificity on mineralocorticoid receptors (MR). Cortisol is a prerequisite for surfactant synthesis and fetal lung maturation. Recently, expression of 11betaHSD2 was demonstrated in human fetal lung, but its localization and possible biological roles remain unknown. Therefore, in this study, we examined immunohistochemical localization of 11betaHSD2, MR, and glucocorticoid receptor (GR) in nonpathological human lungs from fetus to adult (8 weeks gestation to 55 yr of age; n = 40) retrieved from pathology files. Both 11betaHSD2 and MR immunoreactivities were detected in airway epithelia, from bronchiole to trachea and in fetal and neonatal ciliated collecting duct cells of tracheal and bronchial glands, but were undetectable in alveoli. On the other hand, GR was detected in all cell types. These results indicate that 11betaHSD2 colocalizes with MR in human airway epithelia and suggest that 11betaHSD2 play an important role in pulmonary mineralocorticoid activity such as sodium and fluid transport.
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PMID:11Beta-hydroxysteroid dehydrogenase type 2 in human lung: possible regulator of mineralocorticoid action. 981 86

The final control of sodium balance takes place in the cortical collecting duct (CCD) of the nephron, where corticosteroid hormones regulate sodium reabsorption by acting through mineralocorticoid (MR) and/or glucocorticoid (GR) receptors. A clone of principal CCD cells (mpkCCDc14) has been established that is derived from a transgenic mouse (SV40 large T antigen under the control of the SV40 enhancer/L-type pyruvate kinase promoter). Cells grown on filters form polarized monolayers with high electrical transepithelial resistance (R(T) approximately 4700 ohm x cm2) and potential difference (P(D) approximately -50 mV) and have an amiloride-sensitive electrogenic sodium transport, as assessed by the short-circuit current method (Isc approximately 11 microA/cm2). Reverse transcription-PCR experiments using rat MR primers, [3H]aldosterone, and [3H]dexamethasone binding and competition studies indicated that the mpkCCDc14 cells exhibit specific MR and GR. Aldosterone increased Isc in a dose- (10(-10) to 10(-6) M) and time-dependent (2 to 72 h) manner, whereas corticosterone only transiently increased Isc (2 to 6 h). Consistent with the expression of 11beta-hydroxysteroid dehydrogenase type 2, which metabolizes glucocorticoids to inactive 11-dehydroderivates, carbenoxolone potentiated the corticosterone-stimulated Isc. Aldosterone (5x10(-7) M)-induced Isc (fourfold) was associated with a three- to fivefold increase in alpha-ENaC mRNA (but not in those for beta- or gamma-ENaC) and three- to 10-fold increases in alpha-ENaC protein synthesis. In conclusion, this new immortalized mammalian CCD clonal cell line has retained a high level of epithelial differentiation and sodium transport stimulated by aldosterone and therefore represents a useful mammalian cell system for identifying the genes controlled by aldosterone.
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PMID:Corticosteroid-dependent sodium transport in a novel immortalized mouse collecting duct principal cell line. 1023 77

Mineralocorticoid receptors in the inner medullary collecting duct (IMCD) are protected from glucocorticoid binding by an enzyme, 11 beta-hydroxysteroid dehydrogenase type 2 (11 beta-HSD2). To study the role of 11 beta-HSD2 in acid-base homeostasis, 11 beta-HSD2 activity was measured in rat IMCD-enriched cell suspensions. Homogenates of cell suspensions were incubated in buffers ranging in pH from 6.00 to 8.15 in the presence of 1 microCi of 3H-corticosterone (CS) and 400 microM NAD+. Enzyme activity was expressed as the amount of 3H-CS converted to 3H-11-dehydrocorticosterone (DHCS). IMCD 11 beta-HSD2 activity at pH 6.5 was 49% of activity at pH 7.5; 22.5 versus 11.0 fmol/microgram of protein per h. Experiments also were performed on intact cell suspensions at pH 7.5 and 6.5. There was a 42% inhibition in the IMCD cell suspension conversion rate of 3H-CS to 3H-11-DHCS at pH 6.5; 13.1 versus 7.6 fmol/microgram per h (P < 0.005). In cell suspensions at pH 7.5, 1-day acid loading caused a 26% inhibition in conversion rate, 13.2 versus 9.9 fmol/microgram per h (P < 0.05), when compared with controls. These results suggest that during acute metabolic acidosis, IMCD 11 beta-HSD2 is inhibited and may allow access to the mineralocorticoid receptors by glucocorticoids.
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PMID:Inhibition of IMCD 11 beta-hydroxysteroid dehydrogenase type 2 by low pH and acute acid loading. 1049 81

The mammalian distal nephron plays a pivotal role in adjusting urinary sodium excretion. Successive portions of the renal tubule are formed to adapt to this function, and an axial heterogeneity of the distal segments has been defined. The specific transport properties of these epithelia are accomplished by the expression of proteins (cotransporters, exchangers, channels) governing the movement of ions on either cell side. Molecular cloning of these proteins has had a marked impact on the study of their localization and function in the healthy and diseased kidney. Electroneutral cation-chloride cotransporters [Na(K)CC] have been localized to the thick ascending limb and the distal convoluted tubule using specific probes. Proteins implicated in the function of aldosterone target cells, such as the epithelial Na(+) channel (ENaC), the mineralocorticoid receptor (MR) and 11beta-hydroxysteroid dehydrogenase type 2 (11HSD2), an enzyme that confers mineralocorticoid specificity, have been found in the terminal portion of the nephron and the collecting duct. A mineralocorticoid-sensitive component of thiazide-sensitive NaCl transport has been identified in the distal convoluted tubule. Analysis of the ontogeny of these proteins in the maturing kidney has provided a detailed picture of epithelial differentiation and morphological specialization of the renal tubule. The study of mutations of the proteins related with NaCl transport has led to the identification of the molecular causes of inherited human diseases associated with hypo- or hypertension, and the respective sites of an impaired ion transport could be mapped to the renal tubule.
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PMID:Sodium transport-related proteins in the mammalian distal nephron - distribution, ontogeny and functional aspects. 1052 14

The kidney (11-HSD2 or 11-HSDK) isozyme of 11beta-hydroxysteroid dehydrogenase confers specificity for aldosterone on mineralocorticoid receptors in target tissues. In rodent kidney, this isozyme is expressed mainly in cortical collecting ducts and is undetectable in proximal tubules. Using mouse M-1 and rabbit RCD cortical collecting duct cells, we analyzed the 5'-flanking region of the human HSD11K gene encoding this enzyme in an attempt to identify transcriptional regulatory elements responsible for gene expression in the kidney. M-1 and RCD cells had high levels of NAD+ dependent 11-HSD activity with corticosterone as the substrate. Luciferase reporter constructs containing 1785 or 327 nucleotides (nt) upstream of the initiator ATG codon were expressed at similar levels in each cell line, but deletion to 167 nt almost completely abolished expression in both cell types. This region is GC-rich and contain Sp1 binding sites. Electrophoretic mobility shift assays of the region containing the putative Sp1 sites showed several DNA-protein complexes in both the cell types. Mutations of the Sp1 sites decreased transcriptional activity in M-1 cells; however, these mutations had a marginal effect in the RCD cells. These results suggest that elements controlling renal cell type expression are located in the proximal 327 nucleotides of the 5' flanking region of HSD11K.
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PMID:Expression of HSD11K (NAD+ dependent 11beta-hydroxysteroid dehydrogenase) promoter constructs in renal cell lines. 1092 54

Mutations in the HSD11B2 gene encoding the kidney (11-HSD2) isozyme of 11beta-hydroxysteroid dehydrogenase cause apparent mineralocorticoid excess, a form of familial hypertension. Because the hypertension associated with AME is of the salt-sensitive type, it seemed possible that decreases in 11-HSD2 activity might be associated with salt sensitivity. To examine this, Italians with mild hypertension underwent a protocol consisting of a rapid intravenous saline infusion and subsequent furosemide diuresis. To determine whether there were genetic associations between HSD11B2 and salt sensitivity, 198 Italians were genotyped for a CA repeat polymorphism (11 alleles) in the first intron. Increased differences in mean arterial pressure between the sodium loaded and depleted states were correlated with shorter CA repeat length (R=0.214, P=0. 0025). The effect behaved as a recessive trait. This suggested that decreased HSD11B2 expression was associated with shorter CA repeat length. Furthermore, activity of renal 11-HSD2 as measured by an increase in the ratio of urinary-free cortisol/urinary-free cortisone was lower in 33 salt-sensitive subjects (urinary-free cortisol/urinary-free cortisone 0.89+/-0.04 [mean+/-SE]) compared with 34 salt-resistant subjects (0.71+/-0.04, P<0.001). However, when minigenes containing either 14 or 23 CA repeats were transfected into rabbit or human kidney cortical collecting duct cells, the construct with 14 repeats was instead expressed at levels 50% higher than those of the construct with 23 repeats, as determined by reverse transcription-polymerase chain reaction. We conclude that polymorphisms in HSD11B2 and decreased 11-HSD2 activity are associated with sensitivity to sodium loading, but a functional explanation for these associations remains to be elucidated.
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PMID:CA-Repeat polymorphism in intron 1 of HSD11B2 : effects on gene expression and salt sensitivity. 1094 76

Alternating purine-pyrimidine (APP) sequences which might assume left handed DNA helical structures (Z-DNA) could influence the expression of genes in which they were located. There are two such repeat elements in the HSD11B2 (11beta-hydroxysteroid dehydrogenase) gene. First, a CA repeat is located in the first intron. Deletion of this element in a minigene construct leads to a significant decrease (40%) in the expression of the HSD11B2 message in human cortical collecting duct cells. The second APP tract is located approximately 0.9 kb from the last exon or 4.8 kb from the intronic CA repeat element. Deleting this APP tract in a minigene decreases gene expression by 30%. The CA repeat along with its flanking sequences increases luciferase reporter gene expression if placed 5' of the HSD11B2 promoter but not when placed downstream of the reporter gene. Similarly the second APP tract increases luciferase reporter gene expression when placed 5' of the HSD11B2 promoter in an antisense orientation but not in a sense orientation. These results suggests that these dinucleotide repeats influence expression of the HSD11B2 gene in a manner dependent on position and orientation.
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PMID:Transcriptional influence of two poly purine-pyrimidine tracts located in the HSD11B2 (11beta-hydroxysteroid dehydrogenase type 2) gene. 1142 2

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