Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0020538 (hypertension)
 170,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The thiazide-sensitive Na+:Cl- cotransporter is the major salt transport pathway in the distal convoluted tubule of the kidney, and a role of this cotransporter in blood pressure homeostasis has been defined by physiological studies on pressure natriuresis and by its involvement in monogenic diseases that feature arterial hypotension or hypertension. Data base analysis revealed that 135 single nucleotide polymorphisms along the human SLC12A3 gene that encodes the Na+:Cl- cotransporter have been reported. Eight are located within the coding region, and one results in a single amino acid change; the residue glycine at the position 264 is changed to alanine (G264A). This residue is located within the fourth transmembrane domain of the predicted structure. Because Gly-264 is a highly conserved residue, we studied the functional properties of this polymorphism by using in vitro mutagenesis and the heterologous expression system in Xenopus laevis oocytes. G264A resulted in a significant and reproducible reduction ( approximately 50%) in (22)Na+ uptake when compared with the wild type cotransporter. The affinity for extracellular Cl- and for thiazide diuretics was increased in G264A. Western blot analysis showed similar immunoreactive bands between the wild type and the G264A cotransporters, and confocal images of oocytes injected with enhanced green fluorescent protein-tagged wild type and G264A cotransporter showed no differences in the protein surface expression level. These observations suggest that the G264A polymorphism is associated with reduction in the substrate translocation rate of the cotransporter, due to a decrease in the intrinsic activity. Our study also reveals a role of the transmembrane segment 4 in defining the affinity for extracellular Cl- and thiazide diuretics.
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PMID:A single nucleotide polymorphism alters the activity of the renal Na+:Cl- cotransporter and reveals a role for transmembrane segment 4 in chloride and thiazide affinity. 1476 43

Studies on Mendelian hypertension have provided great insight into mechanisms causing hypertension. Mineralocorticoid synthesis and degradation, the mineralocorticoid receptor, sodium channel resorptive mechanisms, and regulation of the thiazide-sensitive sodium-chloride cotransporter have been shown to cause hypertension. Aberrant regulation of peripheral vascular resistance and circulatory regulation have not yet been proved but have been strongly implicated in Mendelian hypertension with brachydactyly. Hypertension as a complex genetic trait has proved more difficult because many genes are involved and the genes have much smaller effects. Association studies, linkage analyses, single nucleotide polymorphism analyses, synteny in animal models, and gene expression studies are the current tools and steady progress is being made.
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PMID:Present status of genetic mechanisms in hypertension. 1487 Oct 48

The deletion of thiazide-sensitive Na-Cl cotransporter ( TSC, SLC12A3) causes Gitelman's syndrome characterized by low blood pressure, while deletions of the WNK1 ( PRKWNK1) and WNK4 ( PRKWNK4) genes cause familial hypertension known as pseudohypoaldosteronism type II. Recent studies have revealed that cell surface expression of TSC is regulated by WNK1 and WNK4. We hypothesized that molecular variations in TSC, WNK1, and WNK4 could lead to an increased morbidity of hypertension. We identified 52, 35, and 21 polymorphisms in Japanese hypertensives by sequencing the entire coding regions of TSC, WNK1 and WNK4, respectively. Twenty-one representative polymorphisms were genotyped in 1,818 Japanese individuals (771 subjects with hypertension and 1,047 controls) randomly sampled in Suita city. The results indicated that the systolic blood pressure in men with the CT+TT genotype in WNK4 C14717T was 3.1 mmHg higher than those with the CC genotype ( p=0.042) after adjustment with confounding factors such as age, BMI, hyperlipidemia, diabetes mellitus, antihypertensive drug use, smoking, and drinking. Multivariate logistic regression analysis (with adjustment for the same parameters) in men revealed that the odds ratio for the presence of hypertension of the CT+TT genotype in C14717T to the CC genotype was 1.62 ( p=0.010, 95% confidence interval, 1.12-2.33). Association of TSC and WNK1 with hypertension was not observed. In conclusion, our study suggests the possible involvement of WNK4 in essential hypertension in a Japanese general population.
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PMID:Identification of 108 SNPs in TSC, WNK1, and WNK4 and their association with hypertension in a Japanese general population. 1530 83

Hypertension is related to sodium intake, and many patients with essential hypertension are overweight and have the metabolic syndrome. We therefore studied microsatellite markers close to the thiazide-sensitive Na-Cl cotransporter on chromosome 16 and a quantitative trait locus for abdominal obesity-metabolic syndrome (AOMS2) on chromosome 17, which have been found to be linked to hypertension in a previous genome scan in Chinese. There were 84 hypertensive subjects (44 men, 40 women, age 53+/-13 years) and 88 normotensive controls (40 men, 48 women, age 54+/-13 years) recruited. Specific oligonucleotide primers were used to amplify genomic DNA spanning the microsatellite markers D16S3396 and D17S1303 that consist of ATA and GATA repeats, respectively. We did not find any association between D16S3396 and blood pressure. In contrast, the distribution of D17S1303 genotypes differed between hypertensive subjects and normal controls (P = 0.014). The number of GATA repeats correlated inversely with diastolic blood pressure (r = -0.18, P = 0.02) and body mass index (r = -0.12, P = 0.01). Nine GATA repeats in D17S1303 were associated with hypertension (OR 2.19, 95% CI 1.08-4.44, P = 0.027), while 14 GATA repeats were associated with normotension (OR 0.26, 95% CI 0.10-0.66, P = 0.002). The diastolic blood pressure in those with or without the (GATA)9 allele was 85.9+/-13.6 and 79.2+/-13.6 mmHg respectively (P = 0.01), and in those with or without the (GATA)14 allele it was 73.8+/-11.0 and 81.8+/-14.0 mmHg respectively (P = 0.003). Our results provide further evidence that a gene predisposing to hypertension in Chinese is in the vicinity of the microsatellite D17S1303.
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PMID:Association of essential hypertension with a microsatellite marker on chromosome 17. 1571 82

The response of blood pressure to thiazide diuretics (TZDs) differs among individuals. The prediction of the antihypertensive effect of TZDs is important for realizing individualized therapy in the management of hypertension. The aim of this study was to identify the single nucleotide polymorphisms (SNPs) susceptible to the antihypertensive effect of TZDs, particularly focusing on genes related to water-electrolyte absorption in the kidney. Seventy-six outpatients (mean age, 65.4+/-9.0 years) with essential hypertension (EHT) taking TZDs were retrospectively assessed. We defined as responders (R) those whose mean blood pressure was lowered by more than 5 mmHg after the use of TZDs. Forty-eight SNPs in 17 genes (ADD1, GNB3, TSC [SLC12A3], MLR [NR3C2], NCX1 [SLC8A1], WNK1, WNK4, AGT, ACE, AT1 [AGTR1], CYP11B2, ADRB1, ADRB2, ADRB3, ADRA1A, ADRA1B, ADRA2A) were genotyped in the 76 patients. The SNPs in TSC, MLR, NCX1, WNK1, and WNK4 were identified by direct sequencing and those with minor frequencies of greater than 5% were genotyped in this study. The comparison of polymorphism prevalence between R and non-responders (NR) showed significant differences in TSC C1784T (C allele vs. T allele, odds ratio (OR)=3.81, p =0.016, confidence interval (CI): 1.25-11.63) and ADRB3 T727C (Trp64Arg) (T allele vs. C allele, OR=4.59, p =0.005, CI: 1.54-13.68). The blood pressure (BP) in patients homozygous for the major alleles of both TSC C1784T and ADRB3 T727C were significantly reduced by TZD treatment; however, the BP in those homozygous for the minor allele and heterozygous (TSC C1784T: TT+CT; ADRB3 T727C: CC+CT) for both SNPs were not significantly changed after TZD treatment. Both newly detected TSC C1784T and ADRB3 T727C are gene polymorphisms susceptible to the antihypertensive effect of TZDs in patients with EHT. Thus, the prediction of BP reduction by TZDs may be possible by evaluating these two SNPs.
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PMID:The thiazide-sensitive Na(+)-Cl(-) cotransporter gene, C1784T, and adrenergic receptor-beta3 gene, T727C, may be gene polymorphisms susceptible to the antihypertensive effect of thiazide diuretics. 1582 64

In models of genetic hypertension, renal tubular dysfunction could be involved in the increased sodium and water reabsorption. However, the molecular basis for the increased renal sodium and water retention remains largely undefined in spontaneously hypertensive rats (SHR). We hypothesized that dysregulation of renal epithelial sodium channels (ENaC), sodium (co)transporters, or aquaporin-2 (AQP2) could be involved in the pathogenesis of hypertension in SHR. Six-week-old or twelve-week-old SHR and corresponding age-matched Wistar-Kyoto control rats (WKY) were studied. In both SHR groups, systolic blood pressure was markedly increased, whereas urine output, creatinine clearance, and urinary sodium excretion were decreased compared with corresponding WKY. Moreover, urine osmolality and urine-to-plasma osmolality ratio were increased compared with WKY. Semiquantitative immunoblotting demonstrated that the protein abundance of beta- and gamma-subunits of ENaC was increased in the cortex and outer stripe of the outer medulla and inner stripe of the outer medulla (ISOM) in SHR, whereas alpha-ENaC abundance was increased in ISOM. Immunoperoxidase microscopy confirmed the increased labeling of beta-ENaC and gamma-ENaC subunits in the late distal convoluted tubule, connecting tubule, and cortical and outer medullary collecting duct segments. In contrast, subcellular localization of alpha-ENaC, beta-ENaC, and gamma-ENaC was not changed. Expression of sodium/hydrogen exchanger type 3, bumetanide-sensitive Na-K-2Cl cotransporter, and thiazide-sensitive Na-Cl cotransporter was not altered in SHR. AQP2 levels were increased in the ISOM in SHR, and immunoperoxidase microscopy demonstrated an increased apical labeling of AQP2 in the inner medullary collecting duct in SHR. These results suggest that the increased protein abundance of ENaC subunits as well as the increased apical targeting of AQP2 may contribute to renal sodium and water retention observed during the development of hypertension in SHR.
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PMID:Increased expression of ENaC subunits and increased apical targeting of AQP2 in the kidneys of spontaneously hypertensive rats. 1595 75

With-no-lysine kinase-1 (WNK1) gene mutations cause familial hyperkalemic hypertension (FHHt), a Mendelian disorder of excessive renal Na+ and K+ retention. Through its catalytic activity, full-length kinase-sufficient WNK1 (L-WNK1) suppresses its paralog, WNK4, thereby upregulating thiazide-sensitive Na-Cl cotransporter (NCC) activity. The predominant renal WNK1 isoform, KS-WNK1, expressed exclusively and at high levels in distal nephron, is a shorter kinase-defective product; the function of KS-WNK1 must therefore be kinase independent. Here, we report a novel role for KS-WNK1 as a dominant-negative regulator of L-WNK1. Na+ transport studies in Xenopus laevis oocytes demonstrate that KS-WNK1 downregulates NCC activity indirectly, by inhibiting L-WNK1. KS-WNK1 also associates with L-WNK1 in protein complexes in oocytes and attenuates L-WNK1 kinase activity in vitro. These observations suggest that KS-WNK1 plays an essential role in the renal molecular switch regulating Na+ and K+ balance; they provide insight into the kidney-specific phenotype of FHHt.
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PMID:Dominant-negative regulation of WNK1 by its kidney-specific kinase-defective isoform. 1646 59

Hyperinsulinemia is associated with hypertension. Dysregulation of renal distal tubule sodium reabsorption may play a role. We evaluated the regulation of the epithelial sodium channel (ENaC) and the thiazide-sensitive Na-Cl cotransporter (NCC) during chronic hyperinsulinemia in rats and correlated these changes to blood pressure as determined by radiotelemetry. Male Sprague-Dawley rats ( approximately 270 g) underwent one of the following three treatments for 4 wk (n = 6/group): 1) control; 2) insulin-infused plus 20% dextrose in drinking water; or 3) glucose water-drinking (20% dextrose in water). Mean arterial pressures were increased by insulin and glucose (mmHg at 3 wk): 98 +/- 1 (control), 107 +/- 2 (insulin), and 109 +/- 3 (glucose), P < 0.01. Insulin (but not glucose) increased natriuretic response to benzamil (ENaC inhibitor) and hydrochlorothiazide (NCC inhibitor) on average by 125 and 60%, respectively, relative to control rats, suggesting increased activity of these reabsorptive pathways. Neither insulin nor glucose affected the renal protein abundances of NCC or the ENaC subunits (alpha, beta, and gamma) in kidney cortex, outer medulla, or inner medulla in a major way, as determined by immunoblotting. However, insulin and to some extent glucose increased apical localization of these subunits in cortical collecting duct principal cells, as determined by immunoperoxidase labeling. In addition, insulin decreased cortical "with no lysine" kinase (WNK4) abundance (by 16% relative to control), which may have increased NCC activity. Overall, insulin infusion increased blood pressure, and NCC and ENaC activity in rats. Increased apical targeting of ENaC and decreased WNK4 expression may be involved.
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PMID:Regulation of blood pressure, the epithelial sodium channel (ENaC), and other key renal sodium transporters by chronic insulin infusion in rats. 1630 59

Hypokalemia is a prominent feature of Gitelman syndrome and a common side effect of thiazide use in the treatment of hypertension. It is widely recognized that genetic or pharmacological inhibition of the renal thiazide-sensitive sodium-chloride cotransporter (NCC) initiates the potentially severe renal potassium loss observed in these settings. Surprisingly, hypokalemia has not been detected in NCC (-/-) mice maintained on normal rodent diets (Schultheis PJ, Lorenz JN, Meneton P, Nieman ML, Riddle TM, Flagella M, Duffy JJ, Doetschman T, Miller ML, and Shull GE. J Biol Chem 273: 29150-29155, 1998). We show that modest reduction of dietary potassium induced a marked reduction in plasma potassium and elevated renal potassium excretion in NCC (-/-) mice that was associated with a pronounced polydipsia and polyuria of central origin. These findings are consistent with the development of potassium depletion in NCC (-/-) mice and were not seen in wild-type mice maintained on the same low-potassium diet. In addition, plasma aldosterone levels were significantly elevated in NCC (-/-) mice even in the presence of a low-potassium diet. Collectively, these findings suggest an early central component to the polyuria of Gitelman syndrome and show that both elevated aldosterone and dietary potassium content contribute to the development of hypokalemia in Gitelman syndrome. Therefore, NCC (-/-) mice are more sensitive to reductions in dietary potassium than wild-type mice and become hypokalemic, thus more faithfully representing the Gitelman phenotype seen in humans.
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PMID:Hypokalemia in a mouse model of Gitelman's syndrome. 1643 71

Gene mutations in WNK4 kinase cause a genetic form of hypertension by affecting multiple ion transport pathways through different mechanisms. Cai et al. report that the inhibitory effect of WNK4 on the thiazide-sensitive sodium-chloride cotransporter occurs through the lysosomal degradation pathway in mammalian cells.
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PMID:Cellular mechanisms of WNK4-mediated regulation of ion transport proteins in the distal tubule. 1668 22


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