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Z Krozowski

Publications and source records attributed to Z Krozowski.

At least 19 recordsLinked to original sources
PubMed2003

Regulation of 11beta-hydroxysteroid dehydrogenase type II expression in the renal epithelial cells.

The regulation of 11beta-hydroxysteroid dehydrogenase type II (11betaHSD2) expression at the level of specific mRNA and 11betaHSD2 protein was investigated in primary culture of renal epithelial cells of the rat. It has been shown that treatment of the SE cells with adenylyl cyclase activator, forskolin, known to stimulate the protein kinase A (PKA) pathway, resulted in an increase in 11betaHSD2 mRNA content in these cells. Semi-quantitative RT-PCR revealed that the effect of forskolin was attenuated by the addition of phorbol ester, tetradecanoyl phorbol acetate (TPA), an activator of the protein kinase C (PKC) pathway, whereas TPA on its own slightly reduced the basal level of 11betaHSD2 expression judging from the content of specific mRNA. Measurements of [35S]-methionine incorporation into immunoprecipitable 11betaHSD2 revealed an increased synthesis of this protein in renal epithelial cells treated with forskolin. Phorbol ester TPA markedly reduced the effect of forskolin on the synthesis of 11betaHSD2 and attenuated the basal level of synthesis of this protein. It is concluded that in renal epithelial cells in primary culture, stimulation of PKA pathway results in the induction of 11betaHSD2 both at a specific mRNA and at a protein level and that this effect is markedly reduced by activation of PKC pathway.

11-beta-Hydroxysteroid Dehydrogenase Type 2↗
PubMed2001

Modulation of 11 beta-hydroxysteroid dehydrogenase type 2 activity in Ishikawa cells is associated with changes in cellular proliferation.

An important determinant of the potency of steroid hormones is the presence of activating and inactivating enzymes in target cells. The 11 beta-hydroxysteroid dehydrogenase type 1 and type 2 enzymes (11 beta HSD1 and 11 beta HSD2) modulate glucocorticoid action and may be important in regulating cellular growth. In the present study we examined 11 beta-hydroxysteroid dehydrogenase in Ishikawa endometrial cancer cells to see if modulation of enzyme activity could potentiate the antiproliferative effects of glucocorticoids. Ishikawa cells contain an NAD dependent enzyme migrating at 41 kDa on Western blots, consistent with the presence of the glucocorticoid-inactivating enzyme 11 beta HSD2, while the NADP dependent 11 beta HSD1 is barely detectable. Given that glucocorticoids decrease cellular proliferation we asked whether inhibition of 11 beta HSD2 could further enhance this effect. Cultivation of cells in the presence of 1 microM cortisol resulted in an elevation of 11 beta HSD2 and this was associated with a decrease in cell number. Enzyme activity and cell proliferation showed a biphasic response to the synthetic anti-progestin and anti-glucocorticoid RU38486, with < or =10 nM exerting agonistic effects and > or =100 nM producing antagonist effects in the presence of 1 microM cortisol. Inhibition of 11 beta HSD2 activity by glycyrrhetinic acid did not enhance the anti-proliferative effects of 1 microM cortisol, but the inhibitor showed significant antiproliferative activity in the absence of added glucocorticoid, consistent with protection of the low levels of glucocorticoids present in culture medium. Interestingly, the commonly used 11 beta HSD inhibitor, Carbenoxolone, did not block 11 beta HSD2 activity in whole Ishikawa cells, and there was no effect on cell proliferation, however, complete inhibition of 11 beta HSD2 was achieved in cellular homogenates suggesting that a barrier exists to entry of the inhibitor into intact cells. This study suggests that inhibition of 11 beta HSD2 activity can enhance the antiproliferative effects of low, but not high concentrations of glucocorticoids, and that beneficial effects may be attained in vivo at the nadir of diurnal glucocorticoid levels.

11-beta-Hydroxysteroid Dehydrogenase Type 2↗
PubMed2001

Pan1b (17betaHSD11)-enzymatic activity and distribution in the lung.

We describe a new member of the 17beta-hydroxysteroid dehydrogenase group of enzymes. Human Pan1b displays greatest activity with 5alpha-androstan-3alpha,17beta-diol (3alpha-Diol) as substrate, suggesting that it may be important in androgen metabolism. Enzymic activity was non-saturable with 3alpha-Diol but saturable with retinoids, although retinoids were not metabolized. Immunohistochemical studies on 10% formalin fixed and paraffin embedded sections of human tissues showed that Pan1b was present in acini and ciliated epithelia of the lung. In the fetus immuno reactivity was present in ciliated epithelia throughout gestation and staining appeared to be stronger in the second half of pregnancy. Pan1b was also expressed in the nonpigmented epithelium of the ciliary body, and in adrenocortical tumor cells. Although 3alpha-Diol is generally considered a degradation product of androgen metabolism it could have its own biological function. Pan1b may be an important modulator of the endocrine, or intracrine activity of this steroid.

17-Hydroxysteroid Dehydrogenases↗
PubMed2001

Cloning and in vitro characterization of alpha 1(I)-collagen 11 beta-hydroxysteroid dehydrogenase type 2 transgenes as models for osteoblast-selective inactivation of natural glucocorticoids.

The NAD-dependent enzyme, 11beta-hydroxysteroid dehydrogenase type II (11 beta HSD2), catalyzes the unidirectional conversion of biologically active glucocorticoids to inactive metabolites. In vivo, 11 beta HSD2 protects the mineralocorticoid receptor from activation by glucocorticoids in mineralocorticoid target tissues such as kidney. The goal of the present study was to use targeted overexpression of 11 beta HSD2 as a novel means of disrupting glucocorticoid signaling in osteoblastic cells. Rat 11 beta HSD2 complementary DNA was cloned downstream of a 2.3- and 3.6-kb alpha 1(I)-collagen (Col1a1) promoter fragment to produce the expression plasmids Col2.3-HSD2 and Col3.6-HSD2, respectively, which were transiently and/or stably transfected in osteoblastic ROS 17/2.8 and MC3T3-E1 cells. Transgene messenger RNA and protein were detected in transfected cells by Northern blot analysis and immunostaining, respectively. Transfection of 11 beta HSD2 led to higher rates of conversion of [(3)H]corticosterone to [(3)H]dehydrocorticosterone and reduced glucocorticoid-dependent regulation of a mouse mammary tumor virus promoter-reporter construct, cell growth, and messenger RNA markers compared with transfection of a control vector. Expression of 11 beta HSD2 under the control of Col1a1 promoter fragments may provide a novel model to study the role of glucocorticoid signaling in osteoblastic cells.

11-beta-Hydroxysteroid Dehydrogenases↗
PubMed2001

Light and electron microscopy localization of the 11beta-hydroxysteroid dehydrogenase type I enzyme in the rat.

The 11beta-hydroxysteroid dehydrogenase type I enzyme (11betaHSD1) converts cortisone to cortisol in humans, and 11-dehydrocorticosterone to corticosterone in rodents. In the present study we used a new immunopurified polyclonal antibody, RAH113, to localize 11betaHSD1 at the light and electron microscopy levels in a wide range of rat tissues. 11betaHSD1 staining in the liver was of highest intensity around the central vein and decreased radially. In the lung, 11betaHSD1 was found at highest levels in the interstitial fibroblast, with levels in the type II pneumocyte an order of magnitude lower. RAH113 stained proximal tubules of the renal cortex and interstitial cells of the medulla and papilla. Adrenal 11betaHSD1 was confined to the glomerulosa and medulla, whereas the glucocorticoid-inactivating hydroxysteroid dehydrogenase isoform 11betaHSD2 was present in fascilulata/reticularis. 11betaHSD1 was found in parietal cells of the fundic region of the stomach, but not in the antrum. In the heart, 11betaHSD1 was detected in cells resembling interstitial fibroblasts of the endocardium and in the adventitial fibroblasts of blood vessels. Western blot analysis confirmed the presence of an antigen of the correct size (34 kDa) and intensity consistent with levels of enzyme activity previously reported in these tissues. Brain and testis also displayed the 34-kDa protein, confirming the expression of authentic 11betaHSD1 in these tissues. Electron microscopy of lung and kidney interstitial cells showed that 11betaHSD1 was localized both to the endoplasmic reticulum and the nuclear membrane. These results show that 11betaHSD1 is present in discrete cell populations where it may facilitate intracrine and paracrine glucocorticoid action in addition to its classical role of maintaining circulating glucocorticoids via activity in the liver.

11-beta-Hydroxysteroid Dehydrogenase Type 2↗
PubMed2000

Role of the 11beta-hydroxysteroid dehydrogenase type 2 in blood pressure regulation.

The renal 11beta-hydroxysteroid dehydrogenase type 2 (11betaHSD2) enzyme inactivates 11-hydroxy steroids in the kidney, thus protecting the nonselective mineralocorticoid receptor (MR) from occupation by glucocorticoids. The gene is highly expressed in all sodium-transporting epithelia, but also in human placenta, pancreas, and thyroid. Mutations in the HSD11B2 gene cause a rare monogenic juvenile hypertensive syndrome called apparent mineralocorticoid excess (AME). In AME, compromised 11betaHSD2 enzyme activity results in overstimulation of the MR by cortisol, causing sodium retention, hypokalemia, and salt-dependent hypertension. Recent evidence suggests a role of the 11betaHSD2 in essential hypertension. We found hypertension with no other characteristic signs of AME in the heterozygous father of a child with AME and in a girl with a homozygous gene mutation resulting in a mild deficiency of 11betaHSD2. Moreover, some studies in patients with essential hypertension showed a prolonged half-life of cortisol and an increased ratio of urinary cortisol to cortisone metabolites, suggesting a deficient 11betaHSD2 activity. These abnormalities may be genetically determined. A genetic association of a microsatellite flanking the HSD11B2 gene and hypertension in black patients with end-stage renal disease has been reported. We recently analyzed a CA-repeat allele polymorphism in unselected patients with essential hypertension, but did not find any correlation between this marker and blood pressure. However, we did find an association between this polymorphic CA microsatellite marker and salt sensitivity. Moreover, the activity of the 11betaHSD2, as shown by elevated mean ratios of urinary cortisol to cortisone metabolites, was decreased in salt-sensitive compared with salt-resistant subjects. These findings indicate that variants of the HSD11B2 gene contribute to the enhanced blood pressure response to salt in humans.

11-beta-Hydroxysteroid Dehydrogenases↗
PubMed1999

The glucocorticoid receptor is essential for maintaining basal and dexamethasone-induced repression of the murine corticosteroid-binding globulin gene.

We have investigated hepatic expression and glucocorticoid regulation of the corticosteroid-binding globulin (CBG) gene in mice lacking a functional glucocorticoid receptor (GR). GR-/- mice show impaired negative feedback in the hypothalamic-pituitary-adrenal axis, resulting in elevated circulating levels of ACTH and corticosterone. This is seen in the neonatal period and continues into adulthood where ACTH and corticosterone levels are increased up to 4-5 fold. Despite high elevation of corticosterone we find no change in mean arterial blood pressure in GR-/- mice and no change in the renal activity of the glucocorticoid-metabolising enzymes 11beta-hydroxysteroid dehydrogenase type-1 (HSD1) and type-2 (HSD2). We do find markedly increased hepatic expression of CBG with a 50% increase in plasma CBG levels. Increased expression of CBG was detected in adult GR-/- mice and also at birth with a greater than 10-fold increase in CBG hepatic mRNA in day-18.5 embryonic GR-/- mice. Adult GR-/- mice were also resistant to dexamethasone-induced repression of CBG expression in the liver. These results indicate that in mice, GR is essential for maintaining the basal level of CBG gene expression in the liver, and is also required for dexamethasone-induced repression of the CBG gene in the adult.

Adrenocorticotropic Hormone↗
PubMed1999

The 11beta-hydroxysteroid dehydrogenases: functions and physiological effects.

The 11beta-hydroxysteroid dehydrogenase enzymes (11beta-HSD) interconvert cortisol and cortisone in man, and corticosterone and 11-dehydrocorticosterone in rodents. Two distantly related congeners have been isolated and conserved domains identified by multiple alignment and hydrophobic cluster analysis. 11Beta-HSD1 in the liver acts mainly as an oxoreductase maintaining circulating glucocorticoid levels. Gene deletion studies suggest it plays an important role in providing elevated local concentrations of hormone. In contrast, 11beta-HSD2 inactivates glucocorticoids and is pivotal in the distal tubule where it protects the mineralocorticoid receptor from occupation, thus endowing specificity on a non-selective receptor. Mutations in 11beta-HSD2 result in sodium retention and severe hypertension, account for the syndrome of apparent mineralocorticoid excess and may be responsible for other forms of hypertension. 11Beta-HSD2 is also present in the placenta where it protects the fetus from high circulating levels of maternal glucocorticoids. Attenuated placental 11beta-HSD2 activity has recently been shown to be associated with intrauterine growth retardation. 11Beta-HSD2 may also play important roles in pulmonary physiology and breast cancer. This review focuses on recent developments.

11-beta-Hydroxysteroid Dehydrogenases↗
PubMed1999

Induction of mineralocorticoid receptor by sodium butyrate in small intestinal (IEC6) and colonic (T84) epithelial cell lines.

Mineralocorticoid action is essential for colonic sodium and water absorption and is mediated via mineralocorticoid receptors in the upper half of colonic crypts. On the other hand, it has been established that sodium butyrate induces differentiation-like phenomenon in vitro. The aim of this study is to investigate whether this bacterial product participates in the regulation of gene and protein expression of mineralocorticoid receptor in vitro. IEC6 and T84 cells were stimulated by sodium butyrate and RNAs extracted. Gene expression of mineralocorticoid receptor was evaluated by northern blotting or semiquantitative RT-PCR. Protein expression was determined in T84 cells using immunohistochemistry. To investigate whether MR induction was associated with cellular differentiation, we also measured alkaline phosphatase in situ. The mineralocorticoid receptor gene was induced by sodium butyrate in both IEC6 and T84 cells. Immunoreactivity increased in butyrate-treated T84 cells, but receptor-containing cells were not uniformly distributed and often formed clusters. Induction of alkaline phosphate activity was also demonstrated in both IEC6 and T84 cells. Double staining by immunoreactivity and alkaline phosphatase activity clearly demonstrated the colocalization of both after butyrate treatment. In conclusion, sodium butyrate up-regulates gene and protein expression of the functionally important mineralocorticoid receptor in epithelial cells, after induction by differentiation-like condition in vitro.

Alkaline Phosphatase↗
PubMed1999

Coexpression of mineralocorticoid receptors and 11beta-hydroxysteroid dehydrogenase 2 in human gastric mucosa.

The role of mineralocorticoids in human gastrointestinal tract is well established. In the stomach, aldosterone is thought to regulate electrolyte transport associated with gastric acid secretion. In mineralocorticoid target organs, the action of the glucocorticoid inactivating enzyme 11beta-hydroxysteroid dehydrogenase type 2 (11beta-HSD2) facilitates aldosterone binding to a nonselective mineralocorticoid receptor (MR) in the face of high levels of circulating glucocorticoids. In the present study, we examined 25 specimens of human stomach for the presence of MR and 11beta-HSD2 using a [3H]aldosterone binding assay, Northern blot analysis, RT-PCR, and immunohistochemistry. Specific [3H]aldosterone binding sites were detected in gastric fundic mucosa, but not in the antrum. In fundic mucosa the Kd was 0.72+/-0.05 nmol/L (mean +/- SE), and Bmax was 6.0+/-1.4 fmol per milligram of protein. Northern blot analysis demonstrated a faint band for MR mRNA at 6.0 kb, although message for 11beta-HSD2 was undetectable. However, RT-PCR demonstrated specific PCR products for both MR and 11beta-HSD2. Immunohistochemistry demonstrated the colocalization of MR and 11beta-HSD2 only in parietal cells. MR-positive cells were further characterized by electron microscopy, confirming the identity of parietal cells. This study shows that parietal cells contain both MR and 11beta-HSD2, suggesting that the human stomach is a novel target organ for mineralocorticoids. Aldosterone may, therefore, regulate biological functions of parietal cells including gastric acid secretion.

11-beta-Hydroxysteroid Dehydrogenases↗
PubMed1997

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.

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.

11-beta-Hydroxysteroid Dehydrogenases↗
PubMed1997

Immunohistochemical and molecular characterization of the rat 11 beta-hydroxysteroid dehydrogenase type II enzyme.

Mineralocorticoid action is facilitated by 11 beta-hydroxysteroid dehydrogenase type II (11 beta HSD2), which metabolizes glucocorticoids and allows aldosterone to bind to the nonselective mineralocorticoid receptor. We have recently demonstrated the presence of the 11 beta HSD2 protein in a wide range of human epithelia, suggesting that it is the sole isoform endowing specificity in man. In the present study we have used an immunopurified polyclonal antibody (RAH23) raised against a C-terminal peptide derived from the cloned rat 11 beta HSD2 protein to perform immunohistochemical and molecular analysis in rat tissues. In frozen sections of rat kidney, strong staining was seen with the RAH23 antibody in the distal tubule; weaker staining was observed in the thick ascending loop of Henle and the medullary and papillary collecting ducts. Punctate cortical staining was observed in the fetus at 20 days gestation and in 8-day-old rats, with a noticeable increase in the staining pattern at 16 days of age. The kidney did not attain the adult pattern of staining until 28 days of age. Epithelia of ileum and colon also stained with RAH23, as did excretory ducts of the submandibular gland. Intrahepatic and excretory bile ducts displayed strong immunoreactivity in the epithelial lining. Rat adrenal glands showed evidence of the 11 beta HSD2 antigen in the zona fasciculata and zona reticularis, but not in the zona glomerulosa or medulla. Western blot analysis with the RAH23 antibody revealed strong bands in the kidney, colon, adrenal gland, and submandibular gland at 40 kDa, colinear with the migration of the cloned 11 beta HSD2 enzyme. A band of medium intensity was also seen at this size in the pancreas, whereas a band of moderate intensity was seen in the bile duct, and weaker bands were noticed in the stomach, small intestine, and liver, with a diffuse band at 36-42 kDa in the prostate. Strong bands were seen in the pancreas and prostate at 78 kDa, with weaker signals in the colon, adrenal, stomach, and bile duct. A number of tissues also displayed multiple bands at about 30 kDa. Enzymatic assays on tissue homogenates showed extensive conversion of corticosterone to its 11-dehydro product in an NAD-dependent manner in the submandibular gland, adrenal gland, and kidney, but not in the pancreas or prostate. This study confirms the ubiquitous presence of 11 beta HSD2 in sodium-transporting epithelia, demonstrates the high level of 11 beta HSD2 protein and enzyme activity in the rat adrenal, and suggests a possible role for the enzyme in the biliary system. Further studies are required to determine the relevance of the various molecular species to the activity, latency, and processing of the enzyme.

11-beta-Hydroxysteroid Dehydrogenases↗
PubMed1997

11 beta-Hydroxysteroid dehydrogenase type II in the human endometrium: localization and activity during the menstrual cycle.

The 11 beta-hydroxysteroid dehydrogenase type II enzyme (11 beta HSD2) is a potent inactivator of glucocorticoids and is present in high amounts in the placental syncytiotrophoblast and sodium-transporting epithelia. Placental 11 beta HSD2 is thought to protect the fetus from high circulating levels of maternal glucocorticoids, whereas the renal enzyme is important in conferring aldosterone specificity on the mineralocorticoid receptor. An isoform of 11 beta HSD (11 beta HSD1) is also present in a wide range of tissues, but usually acts as an oxoreductase, converting the biologically inactive cortisone to cortisol. In the present study we have used an immunopurified antibody to the carboxy-terminus of human 11 beta HSD2 (HUH23) to demonstrate localization of the enzyme in luminal and glandular epithelia of human endometrium. In some specimens staining was uniformly distributed, but in others there was clear evidence of heterogeneity both between and within epithelia. Although 11 beta HSD2 was found mainly in the cytoplasm, some cells showed evidence of nuclear staining only. Western blot analysis showed a band at 41 kDa in endometrium and myometrium, confirming the presence of 11 beta HSD2. Measurement of activity throughout the menstrual cycle showed that mean levels (+/- SEM) of activity were 156 +/- 17 and 6.1 +/- 1.1 pmol product/min.g homogenate protein for 11 beta HSD2 and 11 beta HSD1, respectively. Patients taking combined estrogen/progesterone contraceptives had significantly lower activities of both enzymes (76 +/- 19 and 1.9 +/- 0.4; both P < 0.01) compared with the control group. 11 beta HSD2 activity was significantly higher in the secretory than in the proliferative phase of the cycle in controls (193 +/- 22 vs. 120 +/- 23; P < 0.05). All groups contained outliers with elevated enzyme activities, with some patients displaying 11 beta HSD2 levels comparable to those observed in human kidney (> 1000 pmol/min.g). Further analysis showed that there was a statistically significant correlation (r = 0.43; P < 0.001) between the levels of 11 beta HSD1 and 11 beta HSD2. There was no detectable mineralocorticoid receptor binding in endometrial cytosols prepared from patients with a range of 11 beta HSD2 activities. It remains to be determined whether elevated or suppressed levels of either isoform are associated with fertility or endometrial pathology.

11-beta-Hydroxysteroid Dehydrogenases↗
PubMed1997

Mineralocorticoid receptors, salt, and hypertension.

This review, covering work from the Baker Institute and elsewhere, is divided into four sections. In the first a summary account of two areas-mineralocorticoid receptors and the enzyme 11 beta hyderoxysteroid dehydrogenase-will be given as background. Next is a brief consideration of the three single-gene causes of human hypertension described to date-glucocorticoid-remediable aldosteronism. Liddle's syndrome, and apparent mineralocorticoid excess-in all of which abnormal sodium handling is a feature. Third, the sequelae of aldosterone occupancy of nonepithelial mineralocorticoid receptors will be analyzed in some detail by reviewing studies on experimental mineralocorticoid hypertension and cardiac fibrosis from this laboratory and elsewhere. Finally, three recent studies from this laboratory will be presented: on putative 11-ketosteroid receptors in epithelial tissue, on glucose-PKC potentiation of mineralocorticoid effects on heart cells, and on the necessity for factors/ processes other than the conversion of cortisol to cortisone (or, in the rat, corticosterone to 11-dehydrocorticosterone) to ensure aldosterone-specific effects in mineralocorticoid target tissues.

11-beta-Hydroxysteroid Dehydrogenases↗
PubMed1997

[A case of apparent mineralocorticoid excess caused by type 2 11 beta- hydroxysteroid dehydrogenase deficiency].

The syndrome of apparent mineralocorticoid excess is a recessively inherited form of low renin hypertension. The syndrome is characterised by sodium retention and hypervolemia despite low plasma renin activity and aldosterone levels. Patients with this syndrome have mutations in the 11HSD2 gene which encodes the enzyme which normally converts cortisol in the renal tubule to its inactive form, cortisone. The unconverted cortisol is thus able to bind and activate the mineralocorticoid receptor, displacing its usual ligand, aldosterone, causing the apparent mineralocorticoid excess. We have studied a patient with severe hypertension, low renin and aldosterone, and a chronic hypokalemic alkalosis at age 4. The analysis of cortisone, cortisol and their metabolites showed the specific pattern of the apparent mineralocorticoid excess. In serum and urine, there was a dramatic decrease of cortisone and its metabolite, while cortisol and its metabolites were non affected.

11-beta-Hydroxysteroid Dehydrogenases↗
PubMed1995

Pseudohypoaldosteronism: evaluation of type I receptors by radioreceptor assay and by antireceptor antibodies.

We have previously demonstrated a deficiency of mineralocorticoid receptors in pseudohypoaldosteronism, by radioreceptorassay. We now report findings with an antireceptor antibody derived from the immunogenic region of the receptor. Lymphocytes from normal controls and from two cases of pseudohypoaldosteronism previously shown to lack receptor binding were tested. After the plasma membrane of lymphocytes was permeabilized with methanol the cells were incubated with a 1:200 dilution of antibody followed by fluorescent antirabbit immunoglobulin mouse serum. After washing fluorescence was detected by microscopy and cytofluorimetry in both controls and patients with pseudohypoaldosteronism. Recent studies on mineralocorticoid receptor cDNA in pseudohypoaldosteronism have not established a mutation in the sequence. We thus suggest that the pathogenesis of pseudohypoaldosteronism is not related to an abnormality of the receptor but rather due to intracellular factor(s) which can block the binding of aldosterone to its receptor.

Adult↗
PubMed1995

Familial pseudohypoaldosteronism: a review on the heterogeneity of the syndrome.

Pseudohypoaldosteronism is thought to be a rare salt-losing disorder, caused by resistance to the action of aldosterone. Defective aldosterone receptor binding is present in familial as well as sporadic cases and it has been suggested that the pathogenesis is due to a defect in the aldosterone receptor system. To date, however, molecular genetic analysis has been unable to identify a mutation in the aldosterone receptor gene itself. We have reviewed the findings in patients with pseudohypoaldosteronism, for clues which might enable us to identify the underlying pathogenesis. Although aldosterone receptor binding is regularly decreased or absent in monocytes of patients with pseudohypoaldosteronism, in some patients receptor protein can be detected with a fluorescence-labeled antibody. Receptor protein was detected in patients from familial autosomal dominant families and in sporadic cases, but was undetectable in two patients with the familial recessive form. To further elucidate the pattern of inheritance we studied the response of the renin-angiotensin-aldosterone system to the stimulation by sodium depletion in the familial autosomal dominant form and in two families with sporadic cases. In both "sporadic" families investigated, one parent and one sibling had an exaggerated response of renin and aldosterone to sodium depletion indicating a defect of sodium conservation apparent only during stress, leading to reclassification as familial cases. No additional family member in the "classical" autosomal dominant families responded abnormally to sodium depletion. These findings indicate that pseudohypoaldosteronism is unusually heterogeneous in its clinical, biochemical, and genetic presentations and findings and suggest that its pathogenesis is heterogeneous as well.

Genes, Dominant↗