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Fernandes-Rosa FL, Bueno AC, de Souza RM, de Castro M, dos Santos JE, Foss MC, Zennaro MC, Bettiol H, Barbieri MA, Antonini SR. Mineralocorticoid receptor p.I180V polymorphism: association with body mass index and LDL-cholesterol levels. J Endocrinol Invest 2010; 33:472-7. [PMID: 19955850 DOI: 10.1007/bf03346627] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
BACKGROUND/AIMS Aldosterone and the mineralocorticoid receptor (MR) play a major role in sodium balance and blood pressure control. They are also involved in adipocyte metabolism. The aim of this study was to analyze the association between the MR p.I180V polymorphism with hypertension and markers of cardiovascular risk. DESIGN AND METHODS Case-control study nested within a cohort of 2063 subjects followed since birth to date. All subjects (age 23-25 yr old) from the entire cohort with systolic and diastolic hypertension (no.=126) were paired with 398 normotensive controls. MR p.I180V genotype association with anthropometric and biochemical markers of cardiometabolic risk was tested. RESULTS There was a significant association of the MR p.I180V genotype with body mass index (BMI) and LDL-cholesterol level (p<0.01). Hypertensive subjects carrying the polymorphic G allele (AG or GG genotypes) presented significantly higher BMI (30.0+/-6.0 vs 28.7+/-5.6 kg/m(2); p<0.01) and higher LDL-cholesterol (139.9+/-60.3 vs 109.9+/-35.5 mg/dl; p<0.01). The frequency of the polymorphism MR p.I180V was similar between hypertensive subjects and controls (p=0.15). CONCLUSIONS The MR p.I180V polymorphism seems to be associated with cardiovascular risk factors including BMI and LDL-cholesterol levels. This original in vivo finding reinforces the role of MR in adipocyte biology and in cardiovascular disease.
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Affiliation(s)
- F L Fernandes-Rosa
- Department of Puericulture and Pediatrics, School of Medicine of Ribeirao Preto, University of Sao Paulo, USP. Av Bandeirantes 3900, CEP 14049-900, Ribeirao Preto SP, Brazil
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102
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Polichnowski AJ, Jin C, Yang C, Cowley AW. Role of renal perfusion pressure versus angiotensin II on renal oxidative stress in angiotensin II-induced hypertensive rats. Hypertension 2010; 55:1425-30. [PMID: 20404214 DOI: 10.1161/hypertensionaha.110.151332] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Renal oxidative stress is thought to contribute to both the etiology and the associated renal injury in angiotensin (Ang) II-dependent hypertension. The contribution of Ang II versus elevated renal perfusion pressure (RPP) on albuminuria and renal oxidative stress in this model of hypertension was explored in the present study by chronically servocontrolling RPP to the left kidney and comparing responses with the right uncontrolled kidney and the left kidney of sham rats. Hypertension was produced in Sprague-Dawley rats fed a 4% NaCl diet by chronic IV infusion of Ang II (25 ng/kg per minute). The RPP to the left kidney was servocontrolled to mean daily pressures averaging approximately 120 mm Hg, whereas the uncontrolled kidneys averaged approximately 170 mm Hg over 14 days of Ang II infusion. Ang II infusion resulted in a 2.4-fold increase in albuminuria, which was RPP dependent. Kidneys exposed to both elevated RPP and Ang II (uncontrolled kidneys) displayed a 3.5-fold increase in malondialdehyde excretion and a 37% and 27% increase in renal cortical and outer medullary superoxide production, respectively. Elevated RPP significantly contributed to global renal oxidative stress (70% increase in malondialdehyde excretion) and outer medullary superoxide production. Elevated circulating levels of Ang II, per se, were responsible for a 1.5-fold and 2.0-fold increase in renal cortical and outer medullary NADPH oxidase activity, respectively. In summary, this study demonstrates that elevated RPP is directly responsible for the excess albuminuria in Ang II-infused rats, whereas both elevated RPP and Ang II directly contribute to the observed renal oxidative stress.
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Affiliation(s)
- Aaron J Polichnowski
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI 53226, USA
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103
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Genome-wide association studies of hypertension: have they been fruitful? J Cardiovasc Transl Res 2010; 3:189-96. [PMID: 20560039 DOI: 10.1007/s12265-010-9183-9] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/14/2010] [Accepted: 03/03/2010] [Indexed: 01/11/2023]
Abstract
Over the last two decades candidate gene association studies and genome-wide linkage scans have met with little success in characterizing risk variants for hypertension. Several factors could be responsible for the relative lack of success, although our understanding of the genetics has evolved to support the belief that there are multiple common risk variants, which are associated with hypertension with modest effect sizes. Genome-wide association studies (GWAS) have successfully identified risk loci for several complex polygenic disease states. Until recently, the productivity of GWAS with respect to identifying risk loci for hypertension was limited. In this paper we describe the recent success of GWAS of hypertension in identifying over a dozen loci associated with essential hypertension. We will review these findings, and place these results in the context of the future potential of pharmocogenetics of hypertension.
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104
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Manejo de la hipertensión arterial en niños y adolescentes: recomendaciones de la Sociedad Europea de Hipertensión. HIPERTENSION Y RIESGO VASCULAR 2010. [DOI: 10.1016/j.hipert.2009.06.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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105
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Jung JY, Lee JW, Kim S, Jung ES, Jang HR, Han JS, Joo KW. Altered regulation of renal sodium transporters in salt-sensitive hypertensive rats induced by uninephrectomy. Electrolyte Blood Press 2009; 7:58-66. [PMID: 21468187 PMCID: PMC3041484 DOI: 10.5049/ebp.2009.7.2.58] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2009] [Revised: 11/25/2009] [Accepted: 11/25/2009] [Indexed: 11/05/2022] Open
Abstract
Uninephrectomy (uNx) in young rats causes salt-sensitive hypertension (SSH). Alterations of sodium handling in residual nephrons may play a role in the pathogenesis. Therefore, we evaluated the adaptive alterations of renal sodium transporters according to salt intake in uNx-SSH rats. uNx or sham operations were performed in male Sprague-Dawley rats, and normal-salt diet was fed for 4 weeks. Four experimental groups were used: sham-operated rats raised on a high-salt diet for 2 weeks (CHH) or on a low-salt diet for 1 week after 1 week's high-salt diet (CHL) and uNx rats fed on the same diet (NHH, NHL) as the sham-operated rats were fed. Expression of major renal sodium transporters were determined by semiquantitative immunoblotting. Systolic blood pressure was increased in NHH and NHL groups, compared with CHH and CHL, respectively. Protein abundances of Na(+)/K(+)/2Cl(-) cotransporter (NKCC2) and Na(+)/Cl(-) cotransporter (NCC) in the CHH group were lower than the CHL group. Expression of epithelial sodium channel (ENaC)-γ increased in the CHH group. In contrast, expressions of NKCC2 and NCC in the NHH group didn't show any significant alterations, compared to the NHL group. Expressions of ENaC-α and ENaC-β in the NHH group were higher than the CHH group. Adaptive alterations of NKCC2 and NCC to changes of salt intake were different in the uNx group, and changes in ENaC-α and ENaC-β were also different. These altered regulations of sodium transporters may be involved in the pathogenesis of SSH in the uNx rat model.
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Affiliation(s)
- Ji Yong Jung
- Department of Internal Medicine, Laboratory of Molecular Nephrology, Gachon University of Medicine and Science, Incheon, Korea
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106
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Gray-McGuire C, Song Y, Morris NJ, Stein CM. Comparison of univariate and multivariate linkage analysis of traits related to hypertension. BMC Proc 2009; 3 Suppl 7:S99. [PMID: 20018096 PMCID: PMC2796003 DOI: 10.1186/1753-6561-3-s7-s99] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Complex traits are often manifested by multiple correlated traits. One example of this is hypertension (HTN), which is measured on a continuous scale by systolic blood pressure (SBP). Predisposition to HTN is predicted by hyperlipidemia, characterized by elevated triglycerides (TG), low-density lipids (LDL), and high-density lipids (HDL). We hypothesized that the multivariate analysis of TG, LDL, and HDL would be more powerful for detecting HTN genes via linkage analysis compared with univariate analysis of SBP. We conducted linkage analysis of four chromosomal regions known to contain genes associated with HTN using SBP as a measure of HTN in univariate Haseman-Elston regression and using the correlated traits TG, LDL, and HDL in multivariate Haseman-Elston regression. All analyses were conducted using the Framingham Heart Study data. We found that multivariate linkage analysis was better able to detect chromosomal regions in which the angiotensinogen, angiotensin receptor, guanine nucleotide-binding protein 3, and prostaglandin I2 synthase genes reside. Univariate linkage analysis only detected the AGT gene. We conclude that multivariate analysis is appropriate for the analysis of multiple correlated phenotypes, and our findings suggest that it may yield new linkage signals undetected by univariate analysis.
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Affiliation(s)
- Courtney Gray-McGuire
- Department of Epidemiology and Biostatistics, Case Western Reserve University, 2103 Cornell Road, Cleveland, Ohio 44106, USA
- Oklahoma Medical Research Foundation, 121 North Shartel Avenue, Oklahoma City, Oklahoma 73102, USA
| | - Yeunjoo Song
- Department of Epidemiology and Biostatistics, Case Western Reserve University, 2103 Cornell Road, Cleveland, Ohio 44106, USA
| | - Nathan J Morris
- Department of Epidemiology and Biostatistics, Case Western Reserve University, 2103 Cornell Road, Cleveland, Ohio 44106, USA
| | - Catherine M Stein
- Department of Epidemiology and Biostatistics, Case Western Reserve University, 2103 Cornell Road, Cleveland, Ohio 44106, USA
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107
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Management of high blood pressure in children and adolescents: recommendations of the European Society of Hypertension. J Hypertens 2009; 27:1719-42. [PMID: 19625970 DOI: 10.1097/hjh.0b013e32832f4f6b] [Citation(s) in RCA: 443] [Impact Index Per Article: 29.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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108
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Collier DM, Snyder PM. Extracellular chloride regulates the epithelial sodium channel. J Biol Chem 2009; 284:29320-5. [PMID: 19713212 DOI: 10.1074/jbc.m109.046771] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The extracellular domain of the epithelial sodium channel ENaC is exposed to a wide range of Cl(-) concentrations in the kidney and in other epithelia. We tested whether Cl(-) alters ENaC activity. In Xenopus oocytes expressing human ENaC, replacement of Cl(-) with SO4(2-), H2PO4(-), or SCN(-) produced a large increase in ENaC current, indicating that extracellular Cl(-) inhibits ENaC. Extracellular Cl(-) also inhibited ENaC in Na+-transporting epithelia. The anion selectivity sequence was SCN(-) < SO4(2-) < H2PO4(-) < F(-) < I(-) < Cl(-) < Br(-). Crystallization of ASIC1a revealed a Cl(-) binding site in the extracellular domain. We found that mutation of corresponding residues in ENaC (alpha(H418A) and beta(R388A)) disrupted the response to Cl(-), suggesting that Cl(-) might regulate ENaC through an analogous binding site. Maneuvers that lock ENaC in an open state (a DEG mutation and trypsin) abolished ENaC regulation by Cl(-). The response to Cl(-) was also modulated by changes in extracellular pH; acidic pH increased and alkaline pH reduced ENaC inhibition by Cl(-). Cl(-) regulated ENaC activity in part through enhanced Na+ self-inhibition, a process by which extracellular Na+ inhibits ENaC. Together, the data indicate that extracellular Cl(-) regulates ENaC activity, providing a potential mechanism by which changes in extracellular Cl(-) might modulate epithelial Na+ absorption.
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Affiliation(s)
- Daniel M Collier
- Department of Internal Medicine, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa 52242, USA
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109
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Snyder PM. Down-regulating destruction: phosphorylation regulates the E3 ubiquitin ligase Nedd4-2. Sci Signal 2009; 2:pe41. [PMID: 19602703 DOI: 10.1126/scisignal.279pe41] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
E3 ubiquitin ligases catalyze ubiquitination, which can target specific proteins for degradation. Although a growing number of E3 ubiquitin ligases and their targets have been identified, much less is known about the mechanisms that regulate their activity. A convergence of data indicate that phosphorylation regulates the binding of Nedd4-2, a HECT (homologous to the E6-AP C terminus) domain E3 ubiquitin ligase, to its target, the epithelial Na(+) channel ENaC. Nedd4-2 phosphorylation is emerging as a central convergence point for the regulation of epithelial Na(+) transport.
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Affiliation(s)
- Peter M Snyder
- Department of Internal Medicine and Molecular Physiology and Biophysics, University of Iowa, Iowa City, IA 52242, USA.
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110
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Abstract
Cardiovascular disease is the leading cause of death and disability world-wide. Blood pressure, throughout the range seen in developed countries, is the most important risk factor for cardiovascular disease. Lowering blood pressure within the whole population by lifestyle interventions, such as reducing dietary salt intake and increasing the consumption of fruit and vegetables, will be of great benefit. Blood pressure-lowering trials also demonstrate immense benefits in preventing strokes, heart failure and coronary heart disease. There are no differences in outcome between the different methods used to lower blood pressure and the benefit is proportional to the degree of blood pressure-lowering. Thiazide diuretics are effective in lowering blood pressure and have been the most widely prescribed blood pressure-lowering drugs. They work by causing both sodium and water loss, but also cause potassium loss and a fall in plasma potassium levels. The latter may mitigate the beneficial effects from blood pressure-lowering. Some diuretics, such as spironolactone, affect the distal tubule and do not cause a fall in plasma potassium levels. However, spironolactone has endocrine side-effects associated with the fact that it is not specific for the mineralocorticoid receptor. The development of a more selective aldosterone antagonist without endocrine side-effects could be a major advance as it would be able to oppose the effects of aldosterone, both on sodium retention and potassium loss and the other vascular effects.
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Affiliation(s)
- G A MacGregor
- Blood Pressure Unit, St. George's Hospital Medical School, London, UK
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111
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Schork NJ, Murray SS, Frazer KA, Topol EJ. Common vs. rare allele hypotheses for complex diseases. Curr Opin Genet Dev 2009; 19:212-9. [PMID: 19481926 PMCID: PMC2914559 DOI: 10.1016/j.gde.2009.04.010] [Citation(s) in RCA: 452] [Impact Index Per Article: 30.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2009] [Revised: 04/27/2009] [Accepted: 04/28/2009] [Indexed: 01/08/2023]
Abstract
There has been growing debate over the nature of the genetic contribution to individual susceptibility to common complex diseases such as diabetes, osteoporosis, and cancer. The 'Common Disease, Common Variant (CDCV)' hypothesis argues that genetic variations with appreciable frequency in the population at large, but relatively low 'penetrance' (or the probability that a carrier of the relevant variants will express the disease), are the major contributors to genetic susceptibility to common diseases. The 'Common Disease, Rare Variant (CDRV)' hypothesis, on the contrary, argues that multiple rare DNA sequence variations, each with relatively high penetrance, are the major contributors to genetic susceptibility to common diseases. Both hypotheses have their place in current research efforts.
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Affiliation(s)
- Nicholas J Schork
- Scripps Genomic Medicine, and Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, CA 92037, United States.
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112
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Abstract
Hypertension is the first single modifiable cause of disease burden worldwide. Genes encoding proteins that are involved in the metabolism (CYP3A5) and transport (ABCB1) of drugs and hormones might contribute to blood pressure control in humans. Indeed, recent data have suggested that CYP3A5 and ABCB1 gene polymorphisms are associated with blood pressure in the rat as well as in humans. Interestingly, the effects of these genes on blood pressure appear to be modified by dietary salt intake. This review summarizes what is known regarding the relationships of the ABCB1 and CYP3A5 genes with blood pressure, and discusses the potential underlying mechanisms of the association. If the role of these genes in blood pressure control is confirmed in other populations and other ethnic groups, these findings would point toward a new pathway for blood pressure control in humans.
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Affiliation(s)
- Murielle Bochud
- Institute of Social and Preventive Medicine, Centre Hospitalier Universitaire Vaudois (CHUV) et Université de Lausanne, Rue du Bugnon 17, CH-1005 Lausanne, Switzerland.
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113
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Holloway CD, MacKenzie SM, Fraser R, Miller S, Barr M, Wilkinson D, Forbes GH, Friel E, Connell JMC, Davies E. Effects of genetic variation in the aldosterone synthase (CYP11B2) gene on enzyme function. Clin Endocrinol (Oxf) 2009; 70:363-71. [PMID: 18710464 DOI: 10.1111/j.1365-2265.2008.03383.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
OBJECTIVE Evidence suggests that high levels of aldosterone lead to hypertension and increased risk of cardiovascular disease. Around 15% of patients with essential hypertension have a raised aldosterone to renin ratio (ARR) suggesting that aldosterone production is inappropriately high in relation to its principal agonist angiotensin II. This may be due to increased activity of aldosterone synthase caused by genetic variation in the CYP11B2 gene. We screened the coding region of human CYP11B2 for genetic variants and tested their effects on function in vitro. PROTOCOL Normotensive subjects (n = 69) were screened for sequence variants in the coding region of CYP11B2 by single-stranded conformation polymorphism (SSCP) analysis and sequencing. The effects of nonsynonymous variants on enzyme activity were assessed in JEG-3 cells transiently transfected with wild-type or variant expression plasmids. The conversion of the substrate 11-deoxycorticosterone (DOC) to corticosterone (B) and aldosterone was measured. RESULTS Twenty variants were detected in CYP11B2 and eight analysed functionally (Arg87Gly, Asn281Thr, Gly288Ser, Lys296Asn, Asp335Asn, Gln404Arg, Ala414Pro and His439Tyr). Corticosterone synthesis was unaltered and aldosterone synthesis reduced in variant Arg87Gly; Asn281Thr increased corticosterone and decreased aldosterone production; Gly288Ser increased corticosterone production and abolished aldosterone production; Lys296Asn reduced both corticosterone and aldosterone production; Asp335Asn increased corticosterone synthesis but did not affect aldosterone production. Variants Gln404Arg, Ala414Pro and His439Tyr showed increases in both corticosterone and aldosterone synthesis compared to the wild-type. CONCLUSION The study confirms the genetic variability of the CYP11B2 gene and provides us with additional valuable structure-function information.
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Affiliation(s)
- C D Holloway
- MRC Blood Pressure Group, BHF Cardiovascular Research Centre, 126 University Place, University of Glasgow, G12 8TA, UK
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114
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Hsu HH, Duning K, Meyer HH, Stölting M, Weide T, Kreusser S, van Le T, Gerard C, Telgmann R, Brand-Herrmann SM, Pavenstädt H, Bek MJ. Hypertension in mice lacking the CXCR3 chemokine receptor. Am J Physiol Renal Physiol 2009; 296:F780-9. [PMID: 19129260 DOI: 10.1152/ajprenal.90444.2008] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
The CXC chemokine receptor 3 (CXCR3) has been linked to autoimmune and inflammatory disease, allograft rejection, and ischemic nephropathy. CXCR3 is expressed on endothelial and smooth muscle cells. Although a recent study posited that antagonizing of CXCR3 function may reduce atherosclerosis, the role of CXCR3 in controlling physiological vascular functions remains unclear. This study demonstrates that disruption of CXCR3 leads to elevated mean arterial pressures in anesthetized and conscious mice, respectively. Stimulation of isolated resistance vessels with various vasoconstrictors showed increased contractibility in CXCR3-/- mice in response to angiotensin II (ANG II) and a decreased vasodilatation in response to acetylcholine (ACh). The increased contractibility was related to higher ANG II type 1 receptor (AT1R) expression, whereas the decreased vasodilatation was related to lower M3-ACh receptor expression in the mesenteric arteries of CXCR3-/- mice compared with wild-type mice. The vasodilatatory response to ACh could be antagonized by the nonselective ACh receptor antagonist atropine and the selective M3 receptor antagonist 4-DAMP, but not by M1, M2, and M4 receptor antagonists. Additionally, EMSA studies revealed that transcription factors SP-1 and EGR-1 interact as a complex with the murine AT1R promoter region. Furthermore, we could show increased expression of SP-1 in CXCR3-/- mice indicating an imbalanced SP-1 and EGR-1 complex formation which causes increased AT1R expression and hypertension. The data indicate that CXCR3 receptor is important in vascular contractility and hypertension, possibly through upregulated AT1R expression.
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Affiliation(s)
- Hsiang-Hao Hsu
- Dept. of Internal Medicine, Albert-Schweitzer-Str. 33, D-48149 Münster, Germany
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115
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Shi G, Gu CC, Kraja AT, Arnett DK, Myers RH, Pankow JS, Hunt SC, Rao DC. Genetic effect on blood pressure is modulated by age: the Hypertension Genetic Epidemiology Network Study. Hypertension 2009; 53:35-41. [PMID: 19029486 PMCID: PMC2633773 DOI: 10.1161/hypertensionaha.108.120071] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2008] [Accepted: 11/03/2008] [Indexed: 11/16/2022]
Abstract
Genome-wide linkage analysis was performed for systolic and diastolic blood pressures in the Hypertension Genetic Epidemiology Network. We investigated the role of gene-age interactions using a recently developed variance components method that incorporates age variation in genetic effects. Substantially improved linkage evidence, in terms of both the number of linkage peaks and their significance levels, was observed. Twenty-six linkage peaks were identified with maximum logarithm of odds scores ranging between 3.0 and 4.6, 15 of which were cross-validated by the literature. The chromosomal region 1p36 that showed the highest logarithm of odds score in our study was found to be supported by evidence from 3 studies. The new method also led to vastly improved validation across ethnic groups. Ten of the 15 supported linkage peaks were cross-validated between 2 different ethnic groups, and 2 peaks on chromosomal region 1q31 and 16p11 were validated in 3 ethnic groups. In conclusion, this investigation demonstrates that genetic effects on blood pressure vary by age. The improved genetic linkage results presented here should help to identify the specific genetic variants that explain the observed results.
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Affiliation(s)
- Gang Shi
- Division of Biostatistics, Washington University School of Medicine, Campus Box 8067, 660 S Euclid Ave, St. Louis, MO 63110-1093, USA.
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116
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He FJ, MacGregor GA. A comprehensive review on salt and health and current experience of worldwide salt reduction programmes. J Hum Hypertens 2008; 23:363-84. [PMID: 19110538 DOI: 10.1038/jhh.2008.144] [Citation(s) in RCA: 634] [Impact Index Per Article: 39.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Cardiovascular disease (CVD) is the leading cause of death and disability worldwide. Raised blood pressure (BP), cholesterol and smoking, are the major risk factors. Among these, raised BP is the most important cause, accounting for 62% of strokes and 49% of coronary heart disease. Importantly, the risk is throughout the range of BP, starting at systolic 115 mm Hg. There is strong evidence that our current consumption of salt is the major factor increasing BP and thereby CVD. Furthermore, a high salt diet may have direct harmful effects independent of its effect on BP, for example, increasing the risk of stroke, left ventricular hypertrophy and renal disease. Increasing evidence also suggests that salt intake is related to obesity through soft drink consumption, associated with renal stones and osteoporosis and is probably a major cause of stomach cancer. In most developed countries, a reduction in salt intake can be achieved by a gradual and sustained reduction in the amount of salt added to food by the food industry. In other countries where most of the salt consumed comes from salt added during cooking or from sauces, a public health campaign is needed to encourage consumers to use less salt. Several countries have already reduced salt intake, for example, Japan (1960-1970), Finland (1975 onwards) and now the United Kingdom. The challenge is to spread this out to all other countries. A modest reduction in population salt intake worldwide will result in a major improvement in public health.
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Affiliation(s)
- F J He
- Blood Pressure Unit, Cardiac and Vascular Sciences, St George's, University of London, London, UK.
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117
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Collier DM, Snyder PM. Extracellular protons regulate human ENaC by modulating Na+ self-inhibition. J Biol Chem 2008; 284:792-8. [PMID: 18990692 DOI: 10.1074/jbc.m806954200] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The epithelial Na(+) channel, ENaC, is exposed to a wide range of proton concentrations in the kidney, lung, and sweat duct. We, therefore, tested whether pH alters ENaC activity. In Xenopus oocytes expressing human alpha-, beta-, and gammaENaC, amiloride-sensitive current was altered by protons in the physiologically relevant range (pH 8.5-6.0). Compared with pH 7.4, acidic pH increased ENaC current, whereas alkaline pH decreased current (pH(50) = 7.2). Acidic pH also increased ENaC current in H441 epithelia and in human primary airway epithelia. In contrast to human ENaC, pH did not alter rat ENaC current, indicating that there are species differences in ENaC regulation by protons. This resulted predominantly from species differences in gammaENaC. Maneuvers that lock ENaC in a high open-probability state ("DEG" mutation, proteolytic cleavage) abolished the effect of pH on human ENaC, indicating that protons alter ENaC current by modulating channel gating. Previous work showed that ENaC gating is regulated in part by extracellular Na(+) ("Na(+) self-inhibition"). Based on several observations, we conclude that protons regulate ENaC by altering Na(+) self-inhibition. First, protons reduced Na(+) self-inhibition in a dose-dependent manner. Second, ENaC regulation by pH was abolished by removing Na(+) from the extracellular bathing solution. Third, mutations that alter Na(+) self-inhibition produced corresponding changes in ENaC regulation by pH. Together, the data support a model in which protons modulate ENaC gating by relieving Na(+) self-inhibition. We speculate that this may be an important mechanism to facilitate epithelial Na(+) transport under conditions of acidosis.
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Affiliation(s)
- Daniel M Collier
- Department of Internal Medicine, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa 52242, USA
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118
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Rocco L, Gil FZ, da Fonseca Pletiskaitz TM, de Fátima Cavanal M, Gomes GN. Effect of sodium overload on renal function of offspring from diabetic mothers. Pediatr Nephrol 2008; 23:2053-60. [PMID: 18574600 DOI: 10.1007/s00467-008-0884-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/28/2007] [Revised: 04/23/2008] [Accepted: 04/28/2008] [Indexed: 12/24/2022]
Abstract
The aim if this study was to evaluate the effect of sodium overload on blood pressure and renal function in the offspring of diabetic rat mothers. Diabetes was induced with a single dose of streptozotocin before mating. Experimental groups were control (C), offspring from diabetic mother (D), control with sodium chloride (NaCl) overload (CS), and offspring from diabetic mother submitted to NaCl overload (DS). After weaning, all groups received food ad libitum; groups C and D had water ad libitum, and CS and DS received NaCl 0.15 M as drinking water. Renal morphology and function were evaluated in 3-month-old rats. Glomerular area, macrophage infiltration, interlobular artery wall thickness, and renal vascular resistance were significantly increased in CS, D, and DS compared with C. Renal plasma flow (RPF) and glomerular filtration rate (GFR) were decreased in CS and D compared with C. In DS, GFR and fractional filtration were increased, suggesting a state of hyperfiltration. Hypertension was observed in groups D, CS, and DS from 2 months on and was more severe in DS. Our data suggest that diabetes during intrauterine development and salt overload beginning at an early age can cause hypertension and renal injury. When these conditions were associated, morphological and functional changes were much more intense, suggesting acceleration in the process of kidney injury.
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Affiliation(s)
- Luigi Rocco
- Department of Physiology, Federal University of São Paulo, São Paulo - S.P., Brazil
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119
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Palomino-Doza J, Rahman TJ, Avery PJ, Mayosi BM, Farrall M, Watkins H, Edwards CRW, Keavney B. Ambulatory blood pressure is associated with polymorphic variation in P2X receptor genes. Hypertension 2008; 52:980-5. [PMID: 18852390 DOI: 10.1161/hypertensionaha.108.113282] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The P2X receptor gene family encodes a series of proteins that function as ATP-gated nonselective ion channels. P2X receptor channels are involved in transducing aldosterone-mediated signaling in the distal renal tubule and are potential candidate genes for blood pressure regulation. We performed a family based quantitative genetic association study in 248 families ascertained through a proband with hypertension to investigate the relationship between common genetic variation in the P2X4, P2X6, and P2X7 genes and ambulatory blood pressure. We genotyped 28 single nucleotide polymorphisms, which together captured the common genetic variability in the 3 genes. We corrected our results for multiple comparisons specifying a false discovery rate of 5%. We found significant evidence of association between the single nucleotide polymorphism rs591874 in the first intron of the P2X7 gene and blood pressure. The strongest association was found for nighttime diastolic blood pressure (P=0.0032), although association was present for both systolic and diastolic blood pressures measured by an observer during the day and at night. Genotypes were associated with a 0.2 SD ( approximately 2.5 mm Hg) difference in night diastolic blood pressure per allele and accounted for approximately 1% of the total variability in this measurement. Other suggestive associations were found, but these were nonsignificant after correction for multiple testing. These genetic data suggest that drugs affecting P2X receptor signaling may have promise as clinical antihypertensive agents.
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Affiliation(s)
- Julian Palomino-Doza
- Institute of Human Genetics, Newcastle University, Newcastle upon Tyne, United Kingdom
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120
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Seccia TM, Rossi GP. Clinical Use and Pathogenetic Basis of Laboratory Tests for the Evaluation of Primary Arterial Hypertension. Crit Rev Clin Lab Sci 2008; 42:393-452. [PMID: 16390680 DOI: 10.1080/10408360500295600] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
This review focuses on the laboratory biochemical tests that are useful in the diagnostic approach to the hypertensive patient. A "minimal" diagnostic laboratory work-up, including a small number of tests that are simple and relatively inexpensive, is first described. Because these tests provide basic information on the presence of major cardiovascular (CV) risk factors and target organ damage, and might give some clues to the presence of a secondary form of hypertension (HT), they should be performed on all patients presenting with HT. Other tests that are aimed at assessing the overall CV risk, a major determinant of prognosis that dictates the therapeutic strategy in the individual HT patient, are then discussed. They allow identification of major CV risk factors and associated clinical conditions which, if present, lead to a substantial change of therapeutic strategy. The role of C-reactive protein as a marker of atherosclerosis and its predictive value for CV events are also discussed. Finally, a section is devoted to tests that are currently confined to research purposes, such as markers of endothelial function including endothelin-1, homocysteine and genetic analysis.
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Affiliation(s)
- Teresa M Seccia
- Department of Clinical Methodology and Medical-Surgical Technologies, University of Bari, Bari, Italy
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121
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Agalou S, Butt AN, Chowienczyk P, Swaminathan R. Hypertension and Circulating mRNA for 11β-Hydroxysteroid Dehydrogenase Type II. Ann N Y Acad Sci 2008; 1137:290-5. [DOI: 10.1196/annals.1448.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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122
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Knight KK, Wentzlaff DM, Snyder PM. Intracellular sodium regulates proteolytic activation of the epithelial sodium channel. J Biol Chem 2008; 283:27477-27482. [PMID: 18662987 DOI: 10.1074/jbc.m804176200] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Na(+) transport across epithelia is mediated in part by the epithelial Na(+) channel ENaC. Previous work indicates that Na(+) is an important regulator of ENaC, providing a negative feedback mechanism to maintain Na(+) homeostasis. ENaC is synthesized as an inactive precursor, which is activated by proteolytic cleavage of the extracellular domains of the alpha and gamma subunits. Here we found that Na(+) regulates ENaC in part by altering proteolytic activation of the channel. When the Na(+) concentration was low, we found that the majority of ENaC at the cell surface was in the cleaved/active state. As Na(+) increased, there was a dose-dependent decrease in ENaC cleavage and, hence, ENaC activity. This Na(+) effect was dependent on Na(+) permeation; cleavage was increased by the ENaC blocker amiloride and by a mutation that decreases ENaC activity (alpha(H69A)) and was reduced by a mutation that activates ENaC (beta(S520K)). Moreover, the Na(+) ionophore monensin reversed the effect of the inactivating mutation (alpha(H69A)) on ENaC cleavage, suggesting that intracellular Na(+) regulates cleavage. Na(+) did not alter activity of Nedd4-2, an E3 ubiquitin ligase that modulates ENaC cleavage, but Na(+) reduced ENaC cleavage by exogenous trypsin. Our findings support a model in which intracellular Na(+) regulates cleavage by altering accessibility of ENaC cleavage sites to proteases and provide a molecular explanation for the earlier observation that intracellular Na(+) inhibits Na(+) transport via ENaC (Na(+) feedback inhibition).
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Affiliation(s)
- Kristin K Knight
- Departments of Internal Medicine and Molecular Physiology and Biophysics, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa 52242
| | - Danielle M Wentzlaff
- Departments of Internal Medicine and Molecular Physiology and Biophysics, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa 52242
| | - Peter M Snyder
- Departments of Internal Medicine and Molecular Physiology and Biophysics, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa 52242.
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123
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Johnson RJ, Feig DI, Nakagawa T, Sanchez-Lozada LG, Rodriguez-Iturbe B. Pathogenesis of essential hypertension: historical paradigms and modern insights. J Hypertens 2008; 26:381-91. [PMID: 18300843 PMCID: PMC2742362 DOI: 10.1097/hjh.0b013e3282f29876] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Since its first identification in the late 1800s, a variety of etiologies for essential hypertension have been proposed. In this paper we review the primary proposed hypotheses in the context of both the time in which they were proposed as well as the subsequent studies performed over the years. From these various insights, we propose a current paradigm to explain the renal mechanisms underlying the hypertension epidemic today. Specifically, we propose that hypertension is initiated by agents that cause systemic and intrarenal vasoconstriction. Over time intrarenal injury develops with microvascular disease, interstitial T cell and macrophage recruitment with the induction of an autoimmune response, with local angiotensin II formation and oxidant generation. These changes maintain intrarenal vasoconstriction and hypoxia with a change in local vasoconstrictor-vasodilator balance favoring sodium retention. Both genetic and congenital (nephron number) mechanisms have profound influence on this pathway. As blood pressure rises, renal ischemia is ameliorated and sodium balance restored completely (in salt-resistant) or partially (in salt-sensitive) hypertension, but at the expense of a rightward shift in the pressure natriuresis curve and persistent hypertension.
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Affiliation(s)
- Richard J Johnson
- Division of Nephrology, Hypertension, and Renal Transplantation, University of Florida, Gainesville, Florida 32610-0224, USA.
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124
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Tripathi G, Sharma RK, Baburaj VP, Sankhwar SN, Jafar T, Agrawal S. Genetic risk factors for renal failure among north Indian ESRD patients. Clin Biochem 2008; 41:525-31. [PMID: 18242170 DOI: 10.1016/j.clinbiochem.2008.01.009] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2007] [Revised: 12/31/2007] [Accepted: 01/09/2008] [Indexed: 11/19/2022]
Abstract
OBJECTIVES Angiotensin converting enzyme (ACE), G-Protein couple receptor (G-Prot), endothelial nitric oxide synthase (ecNOS), Leptin -2548G/A and uncoupling protein (UCP2) are potent regulators of intra renal hemodynamics and may be the causative factors contributing to the deterioration of renal functions. In recent years few studies have been published to show the association of these markers with the end stage renal disease (ESRD). Our study was designed to see the role of different genetic factors individually and synergistically in the progression of renal failure. DESIGN AND METHODS The genotypes of these markers were determined by PCR and RFLP. The gene frequencies of ACE, G-protein, ecNOS, Leptin and UCP2 in 184 ESRD patients and 569 healthy controls from North India were compared. RESULTS There was a significant difference between ESRD patients and control groups both in the biochemical parameters and genotype frequencies. The genotype distribution of ACE in patients was significantly different from the controls (p=0.0001; OR=9.428; 95% CI=4.56-19.492). There was no difference observed for the GNB3-825 TT genotype and for ecNOS aa genotype in patient and control groups. The distribution of Leptin -2548G/A genotype and UCP2 genotype in patients were significantly different from that of controls (p=0.0013; OR=2.804; 95% CI=1.501-5.237 and p=0.0001; OR=8.853; 95% CI=3.458-22.667 respectively). CONCLUSIONS Our results propose that the ACE-DD, Leptin AA and UCP2-DD genotype may be potential genetic markers for predicting the causation and progression of chronic renal failures.
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Affiliation(s)
- Gaurav Tripathi
- Department of Medical Genetics, Sanjay Gandhi Post Graduate Institute of Medical Sciences, Raebareli Road, Lucknow, UP, 226014, India
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125
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Abstract
The management of hypertension continues to pose important challenges. Recent developments have established the importance of more rigorous blood pressure control in the community. In the perioperative setting, hypertension has long been recognised as undesirable, although the adverse impact of high blood pressure on the acute risks of elective surgery may have been previously overstated.A number of agents and techniques are available to control blood pressure perioperatively. These include principally general and regional anaesthetics, alpha(2)-adrenoceptor agonists, peripheral alpha(1)- and beta-adrenoceptor antagonists, dihydropyridine calcium channel antagonists, dopamine D(1A)-receptor agonists (fenoldopam), and nitric oxide donors. Recent years have seen important developments in the receptor selectivity of new compounds and in pharmacokinetics, particularly esterase metabolism. The future study of genomics may enable us to identify patients at risk for hypertension-related adverse events and target therapies most effectively to these high-risk groups.
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Affiliation(s)
- Robert Feneck
- Department of Anaesthesia, Guys and St Thomas' Hospitals, London, England.
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126
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Kabra R, Knight KK, Zhou R, Snyder PM. Nedd4-2 induces endocytosis and degradation of proteolytically cleaved epithelial Na+ channels. J Biol Chem 2008; 283:6033-9. [PMID: 18174164 DOI: 10.1074/jbc.m708555200] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
As a pathway for Na(+) reabsorption, the epithelial Na(+) channel ENaC is critical for Na(+) homeostasis and blood pressure control. Na(+) transport is regulated by Nedd4-2, an E3 ubiquitin ligase that decreases ENaC expression at the cell surface. To investigate the underlying mechanisms, we proteolytically cleaved/activated ENaC at the cell surface and then quantitated the rate of disappearance of cleaved channels using electrophysiological and biochemical assays. We found that cleaved ENaC channels were rapidly removed from the cell surface. Deletion or mutation of the Nedd4-2 binding motifs in alpha, beta, and gammaENaC dramatically reduced endocytosis, whereas a mutation that disrupts a YXXØ endocytosis motif had no effect. ENaC endocytosis was also decreased by silencing of Nedd4-2 and by expression of a dominant negative Nedd4-2 construct. Conversely, Nedd4-2 overexpression increased ENaC endocytosis in human embryonic kidney 293 cells but had no effect in Fischer rat thyroid epithelia. In addition to its effect on endocytosis, Nedd4-2 also increased the rate of degradation of the cell surface pool of cleaved alphaENaC. Together the data indicate that Nedd4-2 reduces ENaC surface expression by altering its trafficking at two distinct sites in the endocytic pathway, inducing endocytosis of cleaved channels and targeting them for degradation.
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Affiliation(s)
- Rajesh Kabra
- Departments of Internal Medicine and Molecular Physiology and Biophysics, University of Iowa College of Medicine, Iowa City, IA 52242, USA
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127
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Makhanova N, Hagaman J, Kim HS, Smithies O. Salt-sensitive blood pressure in mice with increased expression of aldosterone synthase. Hypertension 2007; 51:134-40. [PMID: 18039983 DOI: 10.1161/hypertensionaha.107.098897] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
To study the effects of modestly increased expression of aldosterone synthase (AS), we generated mice (AS(hi/hi)) by replacing the 3' untranslated region of AS mRNA with that from a stable mRNA. AS(hi/hi) mice on a normal-salt diet had 1.5 times the wild-type AS mRNA in adrenals, although their blood pressure and plasma aldosterone did not differ from wild-type mice. Changes in dietary salt did not affect the blood pressure of wild-type mice, but AS(hi/hi) mice had approximately 10-mm Hg higher blood pressure on a high-salt diet than on a low-salt diet and than wild-type mice on either diet. The AS(hi/hi) mice on a high-salt diet also had higher plasma aldosterone, lower plasma potassium, and greater renal expression of the alpha subunit of epithelial sodium channel compared with wild-type mice. The AS(hi/hi) mice on a high-salt diet also had more water intake and urine volume and less urine osmolality than wild-type mice. On a low-salt diet, AS(hi/hi) mice maintained normal blood pressure with less activation of the renin-angiotensin-aldosterone system than wild-type mice. The AS(hi/hi) mice also had less water intake and urine volume and higher urine osmolality than wild-type mice. On a medium high-salt diet, AS(hi/hi) mice were more susceptible than wild-type mice to infusion of angiotensin II, having a higher blood pressure, greater cardiac hypertrophy, and increased oxidative stress. Thus, a modest increase in AS expression makes blood pressure more sensitive to salt, suggesting that genetically increased AS expression in humans may contribute to hypertension and cardiovascular complications in societies with high-salt diets.
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Affiliation(s)
- Natalia Makhanova
- Department of Pathology and Laboratory Medicine, University of North Carolina at Chapel Hill, 701 Brinkhous-Bullitt Building, Chapel Hill, NC 27599-7525, USA
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128
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McArdle PF, Dytch H, O'Connell JR, Shuldiner AR, Mitchell BD, Abney M. Homozygosity by descent mapping of blood pressure in the Old Order Amish: evidence for sex specific genetic architecture. BMC Genet 2007; 8:66. [PMID: 17908314 PMCID: PMC2071912 DOI: 10.1186/1471-2156-8-66] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2007] [Accepted: 10/01/2007] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND High blood pressure is a well established risk factor for morbidity and mortality acting through heart disease, stroke and cardiovascular disease. Genome wide scans have linked regions of nearly every human chromosome to blood pressure related traits. We have capitalized on beneficial qualities of the Old Order Amish of Lancaster, PA, a closed founder population with a relatively small number of founders, to perform a genome wide homozygosity by descent mapping scan. Each individual in the study has a non zero probability of consanguinity. Systolic and diastolic blood pressures are shown to have appreciable dominance variance components. RESULTS Areas of two chromosomes were identified as suggestive of linkage to SBP and 5 areas to DBP in either the overall or sex specific analyses. The strongest evidence for linkage in the overall sample was to Chromosome 18q12 (LOD = 2.6 DBP). Sex specific analyses identified a linkage on Chromosome 4p12-14 (LOD in men only = 3.4 SBP). At Chromosome 2q32-33, an area where we previously reported significant evidence for linkage to DBP using a conventional identity by descent approach, the LOD was 1.4; however an appreciable sex effect was observed with men accounting for most of the linkage (LOD in men only = 2.6). CONCLUSION These results add evidence to a sex specific genetic architecture to blood pressure related traits, particularly in regions of linkage on chromosome 2, 4 and 18.
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Affiliation(s)
- Patrick F McArdle
- Department of Medicine, University of Maryland School of Medicine, Baltimore, MD USA
| | - Harvey Dytch
- Department of Human Genetics, University of Chicago, Chicago, IL USA
| | - Jeffery R O'Connell
- Department of Medicine, University of Maryland School of Medicine, Baltimore, MD USA
| | - Alan R Shuldiner
- Department of Medicine, University of Maryland School of Medicine, Baltimore, MD USA
- Geriatrics Research and Education Clinical Center, Veterans Administration Hospital Medical Center, Baltimore, MD USA
| | - Braxton D Mitchell
- Department of Medicine, University of Maryland School of Medicine, Baltimore, MD USA
| | - Mark Abney
- Department of Human Genetics, University of Chicago, Chicago, IL USA
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129
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Rutherford S, Cai G, Lopez-Alvarenga JC, Kent JW, Voruganti VS, Proffitt JM, Curran JE, Johnson MP, Dyer TD, Jowett JB, Bastarrachea RA, Atwood LD, Goring HHH, Maccluer JW, Moses EK, Blangero J, Comuzzie AG, Cole SA. A chromosome 11q quantitative-trait locus influences change of blood-pressure measurements over time in Mexican Americans of the San Antonio Family Heart Study. Am J Hum Genet 2007; 81:744-55. [PMID: 17846999 PMCID: PMC2227924 DOI: 10.1086/521151] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2007] [Accepted: 06/20/2007] [Indexed: 01/16/2023] Open
Abstract
Although previous genome scans have searched for quantitative-trait loci (QTLs) influencing variation in blood pressure (BP), few have investigated the rate of change in BP over time as a phenotype. Here, we compare results from genomewide scans to localize QTLs for systolic, diastolic, and mean arterial BPs (SBP, DBP, and MBP, respectively) and for rates of change in systolic, diastolic, and mean arterial BPs (rSBP, rDBP, and rMBP, respectively), with use of the longitudinal data collected about Mexican Americans of the San Antonio Family Heart Study (SAFHS). Significant evidence of linkage was found for rSBP (LOD 4.15) and for rMBP (LOD 3.94) near marker D11S4464 located on chromosome 11q24.1. This same chromosome 11q region also shows suggestive linkage to SBP (LOD 2.23) and MBP (LOD 2.37) measurements collected during the second clinic visit. Suggestive evidence of linkage to chromosome 5 was also found for rMBP, to chromosome 16 for rSBP, and to chromosomes 1, 5, 6, 7, and 21 for the single-time-point BP traits collected at the first two SAFHS clinic visits. We also present results from fine mapping the chromosome 11 QTL with use of SNP-association analysis within candidate genes identified from a bioinformatic search of the region and from whole-genome transcriptional expression data collected from 1,240 SAFHS participants. Our results show that the use of longitudinal BP data to calculate the rate of change in BP over time provides more information than do the single-time measurements, since they reveal physiological trends in the subjects that a single-time measurement could never capture. Further investigation of this region is necessary for the identification of the genetic variation responsible for QTLs influencing the rate of change in BP.
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Affiliation(s)
- Sue Rutherford
- Department of Genetics, Southwest Foundation for Biomedical Research, San Antonio, TX 78245-0549, USA.
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130
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Lang F, Vallon V, Knipper M, Wangemann P. Functional significance of channels and transporters expressed in the inner ear and kidney. Am J Physiol Cell Physiol 2007; 293:C1187-208. [PMID: 17670895 DOI: 10.1152/ajpcell.00024.2007] [Citation(s) in RCA: 146] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
A number of ion channels and transporters are expressed in both the inner ear and kidney. In the inner ear, K+cycling and endolymphatic K+, Na+, Ca2+, and pH homeostasis are critical for normal organ function. Ion channels and transporters involved in K+cycling include K+channels, Na+-2Cl−-K+cotransporter, Na+/K+-ATPase, Cl−channels, connexins, and K+/Cl−cotransporters. Furthermore, endolymphatic Na+and Ca2+homeostasis depends on Ca2+-ATPase, Ca2+channels, Na+channels, and a purinergic receptor channel. Endolymphatic pH homeostasis involves H+-ATPase and Cl−/HCO3−exchangers including pendrin. Defective connexins (GJB2 and GJB6), pendrin (SLC26A4), K+channels (KCNJ10, KCNQ1, KCNE1, and KCNMA1), Na+-2Cl−-K+cotransporter (SLC12A2), K+/Cl−cotransporters (KCC3 and KCC4), Cl−channels (BSND and CLCNKA + CLCNKB), and H+-ATPase (ATP6V1B1 and ATPV0A4) cause hearing loss. All these channels and transporters are also expressed in the kidney and support renal tubular transport or signaling. The hearing loss may thus be paralleled by various renal phenotypes including a subtle decrease of proximal Na+-coupled transport (KCNE1/KCNQ1), impaired K+secretion (KCNMA1), limited HCO3−elimination (SLC26A4), NaCl wasting (BSND and CLCNKB), renal tubular acidosis (ATP6V1B1, ATPV0A4, and KCC4), or impaired urinary concentration (CLCNKA). Thus, defects of channels and transporters expressed in the kidney and inner ear result in simultaneous dysfunctions of these seemingly unrelated organs.
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Affiliation(s)
- Florian Lang
- Department of Physiology, Eberhard-Karls-University of Tübingen, Gmelinstrasse 5, Tübingen, Germany.
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131
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Mueller GM, Kashlan OB, Bruns JB, Maarouf AB, Aridor M, Kleyman TR, Hughey RP. Epithelial sodium channel exit from the endoplasmic reticulum is regulated by a signal within the carboxyl cytoplasmic domain of the alpha subunit. J Biol Chem 2007; 282:33475-33483. [PMID: 17855354 DOI: 10.1074/jbc.m707339200] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Epithelial sodium channels (ENaCs) are assembled in the endoplasmic reticulum (ER) from alpha, beta, and gamma subunits, each with two transmembrane domains, a large extracellular loop, and cytoplasmic amino and carboxyl termini. ENaC maturation involves transit through the Golgi complex where Asn-linked glycans are processed to complex type and the channel is activated by furin-dependent cleavage of the alpha and gamma subunits. To identify signals in ENaC for ER retention/retrieval or ER exit/release, chimera were prepared with the interleukin alpha subunit (Tac) and each of the three cytoplasmic carboxyl termini of mouse ENaC (Tac-Ct) or with gamma-glutamyltranspeptidase and each of the three cytoplasmic amino termini (Nt-GGT). By monitoring acquisition of endoglycosidase H resistance after metabolic labeling, we found no evidence of ER retention of any chimera when compared with control Tac or GGT, but we did observe enhanced exit of Tac-alphaCt when compared with Tac. ER exit of ENaC was assayed after metabolic labeling by following the appearance of cleaved alpha as cleaved alpha subunit, but not non-cleaved alpha, is endoglycosidase H-resistant. Interestingly ER exit of epitope-tagged and truncated alpha (alphaDelta624-699-V5) with full-length betagamma was similar to wild type alpha (+betagamma), whereas ER exit of ENaC lacking the entire cytoplasmic carboxyl tail of alpha (alphaDelta613-699-V5 +betagamma) was significantly reduced. Subsequent analysis of ER exit for ENaCs with mutations within the intervening sequence (613)HRFRSRYWSPG(623) within the context of the full-length alpha revealed that mutation alphaRSRYW(620) to AAAAA significantly reduced ER exit. These data indicate that ER exit of ENaC is regulated by a signal within the alpha subunit carboxyl cytoplasmic tail.
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Affiliation(s)
| | | | | | | | - Meir Aridor
- Department of Cell Biology and Physiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261
| | - Thomas R Kleyman
- Renal-Electrolyte Division, Department of Medicine; Department of Cell Biology and Physiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261.
| | - Rebecca P Hughey
- Renal-Electrolyte Division, Department of Medicine; Department of Cell Biology and Physiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261
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Tung J, Rudolph J, Altmann J, Alberts SC. Parallel effects of genetic variation in ACE activity in baboons and humans. AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY 2007; 134:1-8. [PMID: 17503445 DOI: 10.1002/ajpa.20614] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Like humans, savannah baboons (Papio sp.) show heritable interindividual variation in complex physiological phenotypes. One prominent example of such variation involves production of the homeostatic regulator protein angiotensin converting enzyme (ACE), which shows heritable variation in both baboons and humans. In humans, this phenotypic variation is associated with an Alu insertion-deletion polymorphism in the ACE gene, which explains approximately half of the variation in serum ACE activity. We identified a similar Alu insertion-deletion polymorphism in the baboon ACE homologue and measured its frequency in a wild population and a captive population of baboons. We also analyzed the contribution of ACE genotype at this indel to variation in serum ACE activity in the captive population. When conditioned on weight, a known factor affecting ACE activity in humans, age and ACE genotype both accounted for variance in ACE activity; in particular, we identified a significant nonadditive interaction between age and genotype. A model incorporating this interaction effect explained 21.6% of the variation in residual serum ACE activity. Individuals homozygous for the deletion mutation exhibited significantly higher levels of ACE activity than insertion-deletion heterozygotes at younger ages (10-14 years), but showed a trend towards lower levels of ACE activity compared with heterozygotes at older ages (> or =15 years). These results demonstrate an interesting parallel between the genetic architecture underlying ACE variation in humans and baboons, suggesting that further attention should be paid in humans to the relationship between ACE genetic variation and aging.
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Affiliation(s)
- Jenny Tung
- Department of Biology, Duke University, Durham, NC 27708, USA.
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Abstract
The past decade has seen tremendous advances in our understanding of the molecular and genetic basis of many neuropsychiatric disorders. Although the genetic aberrations that lead to these syndromes have been identified in many cases, not much is known about specific gene products and their function. This article reviews the molecular basis of well-known neurogenetic disorders. The syndromes discussed here follow a Mendelian pattern of inheritance and are predominantly single-gene disorders; however, most childhood and adolescent psychiatric disorders are polygenic in nature. This genetic complexity and heterogeneity has made it difficult to identify the genes involved in their etiology. Identification of genetic and environmental risk factors involved in the etiology of complex disorders, such as autism, will help in the discovery of medications that can ameliorate the symptoms.
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134
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Arnett DK, Baird AE, Barkley RA, Basson CT, Boerwinkle E, Ganesh SK, Herrington DM, Hong Y, Jaquish C, McDermott DA, O'Donnell CJ. Relevance of Genetics and Genomics for Prevention and Treatment of Cardiovascular Disease. Circulation 2007; 115:2878-901. [PMID: 17515457 DOI: 10.1161/circulationaha.107.183679] [Citation(s) in RCA: 156] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Atherosclerotic cardiovascular disease (CVD) is a major health problem in the United States and around the world. Evidence accumulated over decades convincingly demonstrates that family history in a parent or a sibling is associated with atherosclerotic CVD, manifested as coronary heart disease, stroke, and/or peripheral arterial disease. Although there are several mendelian disorders that contribute to CVD, most common forms of CVD are believed to be multifactorial and to result from many genes, each with a relatively small effect working alone or in combination with modifier genes and/or environmental factors. The identification and the characterization of these genes and their modifiers would enhance prediction of CVD risk and improve prevention, treatment, and quality of care. This scientific statement describes the approaches researchers are using to advance understanding of the genetic basis of CVD and details the current state of knowledge regarding the genetics of myocardial infarction, atherosclerotic CVD, hypercholesterolemia, and hypertension. Current areas of interest and investigation--including gene-environment interaction, pharmacogenetics, and genetic counseling--are also discussed. The statement concludes with a list of specific recommendations intended to help incorporate usable knowledge into current clinical and public health practice, foster and guide future research, and prepare both researchers and practitioners for the changes likely to occur as molecular genetics moves from the laboratory to clinic.
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135
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Abstract
The devastating long-term consequences of high blood pressure include stroke, heart disease, atherosclerosis, renal disease, and other end-organ damage. From a physiologic perspective, it is not apparent why the propensity for hypertension is so widespread in the general population. Clearly, an adequate arterial pressure is essential for perfusion of the tissues to provide adequate oxygenation and nutrition to the brain and other critical organs. Although the various microcirculatory beds have the capability to adjust vascular resistance to autoregulate blood flow, systemic arterial pressure is usually maintained at levels greater than required for requisite tissue perfusion. The myriad of neurohumoral mechanisms designed to protect against decreases in systemic arterial pressure provide a reserve capacity for increased perfusion when there are increased tissue demands. The unfortunate consequence of having these powerful physiologic control mechanisms is that they may be inappropriately activated in certain circumstances or by genetically determined traits, leading to hypertension and cardiovascular injury. Evidence continues to accumulate indicating that the kidney not only is victim to hypertension-related injury, but also contributes as a villain to the hypertensinogenic process.
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Affiliation(s)
- L Gabriel Navar
- Department of Physiology, Hypertension and Renal Center, Tulane University Health Sciences Center, New Orleans, LA 70112, USA.
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136
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Zhou R, Patel SV, Snyder PM. Nedd4-2 catalyzes ubiquitination and degradation of cell surface ENaC. J Biol Chem 2007; 282:20207-12. [PMID: 17502380 DOI: 10.1074/jbc.m611329200] [Citation(s) in RCA: 165] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Epithelial Na(+) absorption is regulated by Nedd4-2, an E3 ubiquitin-protein ligase that reduces expression of the epithelial Na(+) channel ENaC at the cell surface. Defects in this regulation cause Liddle syndrome, an inherited form of hypertension. Previous work found that Nedd4-2 binds to ENaC via PY motifs located in the C termini of alpha-, beta-, and gammaENaC. However, little is known about the mechanism by which Nedd4-2 regulates ENaC surface expression. Here we found that Nedd4-2 catalyzes ubiquitination of alpha-, beta-, and gammaENaC; Nedd4-2 overexpression increased ubiquitination, whereas Nedd4-2 silencing decreased ubiquitination. Although Nedd4-2 increased both mono/oligoubiquitinated and multiubiquitinated forms of ENaC, monoubiquitination was sufficient for Nedd4-2 to reduce ENaC surface expression and reduce ENaC current. Ubiquitination was disrupted by Liddle syndrome-associated mutations in ENaC or mutation of the catalytic HECT domain in Nedd4-2. Several findings suggest that the interaction between Nedd4-2 and ENaC is localized to the cell surface. First, Nedd4-2 bound to a population of ENaC at the cell surface. Second, Nedd4-2 catalyzed ubiquitination of cell surface ENaC. Third, Nedd4-2 selectively reduced ENaC expression at the cell surface but did not alter the quantity of immature ENaC in the biosynthetic pathway. Finally, Nedd4-2 induced degradation of the cell surface pool of ENaC. Together, the data suggest a model in which Nedd4-2 binds to and ubiquitinates ENaC at the cell surface, which targets surface ENaC for degradation, and thus, reduces epithelial Na(+) transport.
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Affiliation(s)
- Ruifeng Zhou
- Departments of Internal Medicine and Molecular Physiology and Biophysics, University of Iowa College of Medicine, Iowa City, IA 52242, USA
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137
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He FJ, MacGregor GA. Blood pressure is the most important cause of death and disability in the world. Eur Heart J Suppl 2007. [DOI: 10.1093/eurheartj/sum005] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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138
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Tanemoto M. Regulatory mechanism of "K+recycling" for Na +reabsorption in renal tubules. Clin Exp Nephrol 2007; 11:1-6. [PMID: 17384992 DOI: 10.1007/s10157-006-0447-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2006] [Accepted: 10/27/2006] [Indexed: 01/05/2023]
Abstract
Hypertension is one of the predominant risk factors for the progression of renal impairment, and the most common disorder in industrialized societies. Because reduction of the systemic blood pressure in hypertension can halt the progression of renal impairment, it is imperative to appropriately control the systemic blood pressure. Recent genetic analysis has reconfirmed that renal maladjustment of Na(+)-homeostasis, which determines the extracellular fluid volume, is a key element in the pathogenesis of hypertension. The distal tubules adjust the net Na(+)-excretion according to Na(+)-ingestion and maintain the Na(+)-homeostasis. The distal convoluted tubules and the connecting tubules are the predominant sites for the adjustment in individuals with a modern lifestyle. In these tubules, Na(+)-reabsorption depends on "K(+)-recycling", which is conducted through K(+) channels. Because the functional expression of K(+) channels in these tubules is regulated by signal motifs for intracellular localization, the adjustment of "K(+)-recycling" through the modification of signal motifs could be a new target for the treatment of hypertension.
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Affiliation(s)
- Masayuki Tanemoto
- Division of Nephrology, Hypertension and Endocrinology, Department of Medicine, Tohoku University Graduate School of Medicine, 1-1 Seiryo-cho, Aoba-ku, Sendai, 980-8574, Japan.
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139
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Clemitson JR, Dixon RJ, Haines S, Bingham AJ, Patel BR, Hall L, Lo M, Sassard J, Charchar FJ, Samani NJ. Genetic dissection of a blood pressure quantitative trait locus on rat chromosome 1 and gene expression analysis identifies SPON1 as a novel candidate hypertension gene. Circ Res 2007; 100:992-9. [PMID: 17332427 PMCID: PMC3533402 DOI: 10.1161/01.res.0000261961.41889.9c] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
A region with a major effect on blood pressure (BP) is located on rat chromosome 1. We have previously isolated this region in reciprocal congenic strains (WKY.SHR-Sa and SHR.WKY-Sa) derived from a cross of the spontaneously hypertensive rat (SHR) with the Wistar-Kyoto rat (WKY) and shown that there are 2 distinct BP quantitative trait loci, BP1 and BP2, in this region. Sisa1, a congenic substrain from the SHR.WKY-Sa animals carrying an introgressed segment of 4.3Mb, contains BP1. Here, we report further dissection of BP1 by the creation of 2 new mutually exclusive congenic substrains (Sisa1a and Sisa1b) and interrogation of candidate genes by expression profiling and targeted transcript sequencing. Only 1 of the substrains (Sisa1a) continued to demonstrate a BP difference but with a reduced introgressed segment of 3Mb. Exonic sequencing of the 20 genes located in the Sisa1a region did not identify any major differences between SHR and WKY. However, microarray expression profiling of whole kidney samples and subsequent quantitative RT-PCR identified a single gene, Spon1 that exhibited significant differential expression between the WKY and SHR genotypes at both 6 and 24 weeks of age. Western blot analysis confirmed an increased level of the Spon1 gene product in SHR kidneys. Spon1 belongs to a family of genes with antiangiogenic properties. These findings justify further investigation of this novel positional candidate gene in BP control in hypertensive rat models and humans.
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Affiliation(s)
- Jenny-Rebecca Clemitson
- Department of Cardiovascular Sciences, University of Leicester, Glenfield Hospital, Leicester, LE3 9QP, United Kingdom
| | - Richard J. Dixon
- Department of Cardiovascular Sciences, University of Leicester, Glenfield Hospital, Leicester, LE3 9QP, United Kingdom
| | - Steve Haines
- Department of Cardiovascular Sciences, University of Leicester, Glenfield Hospital, Leicester, LE3 9QP, United Kingdom
| | - Andrew J. Bingham
- Department of Cardiovascular Sciences, University of Leicester, Glenfield Hospital, Leicester, LE3 9QP, United Kingdom
| | - Bhakti R. Patel
- Department of Cardiovascular Sciences, University of Leicester, Glenfield Hospital, Leicester, LE3 9QP, United Kingdom
| | - Laurence Hall
- Department of Cardiovascular Sciences, University of Leicester, Glenfield Hospital, Leicester, LE3 9QP, United Kingdom
| | - Ming Lo
- Departement de Physiologie et Pharmacologie Clinique, Faculte de Pharmacie, 69373 Lyon cedex 08, France
| | - Jean Sassard
- Departement de Physiologie et Pharmacologie Clinique, Faculte de Pharmacie, 69373 Lyon cedex 08, France
| | - Fadi J. Charchar
- Department of Cardiovascular Sciences, University of Leicester, Glenfield Hospital, Leicester, LE3 9QP, United Kingdom
| | - Nilesh J. Samani
- Department of Cardiovascular Sciences, University of Leicester, Glenfield Hospital, Leicester, LE3 9QP, United Kingdom
- Corresponding author. Professor N J. Samani, Department of Cardiovascular Sciences, University of Leicester, Glenfield Hospital, Leicester, LE3 9QP, U.K. Tel No. +44 116 2563021, Fax No. +44 116 2875792, E-mail:
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140
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Baráth A, Endreffy E, Bereczki C, Gellén B, Szücs B, Németh I, Túri S. Endothelin-1 gene and endothelial nitric oxide synthase gene polymorphisms in adolescents with juvenile and obesity-associated hypertension. ACTA ACUST UNITED AC 2007; 94:49-66. [PMID: 17444275 DOI: 10.1556/aphysiol.94.2007.1-2.6] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Hypertension is an increasing public health problem all over the world. Essential hypertension accounts for more than 90% of cases of hypertension. It is a complex genetic, environmental and demographic trait. New method in molecular biology has been proposed a number of candidate genes, but the linkage or association with hypertension has been problematic (lack of gene-gene and gene-environment interaction). It is well known that genetic influences are more important in younger hypertensives, because children are relatively free from the common environmental factors contributing to essential hypertension. The association studies compare genotype ferquencies of the candidate gene between patient groups and the controls, in pathways known to be involved in blood pressure regulation. This study examined three polymorphisms of these factors encoding genes (ET-1 G+5665T (Lys198Asn), endothelial nitric oxide synthase (eNOS) T-786C promoter polymorphism and 27-bp repeat polymorphism in intron 4) in adolescents with juvenile essential and obesity-associated hypertension. Significant differences were found in the G/T genotype of the ET-1 polymorphism in the hypertensive and obese+hypertensive patients (body mass index (BMI) > 30). A strong association was detected between the BMI and the polymorphism of the ET-1 gene. It seems that ET-1 gene polymorphism plays a role in the development of juvenile hypertension associated with obesity. Although no significant differences were seen in the case of the eNOS promoter polymorphism and the eNOS 4th intron 27-bp repeat polymorphism. It seems that eNOS may play a role, but this is not the main factor in the control of blood pressure; it is rather a fine regulator in this process. This study with adolescents facilitates an understanding of the genetic factors promoting juvenile hypertension and obesity.
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Affiliation(s)
- A Baráth
- Department of Pediatrics, Albert Szent-Györgyi Medical and Pharmaceutical Center, University of Szeged, Korányi fasor 14-15, H-6721 Szeged, Hungary.
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141
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Bengrine A, Li J, Awayda MS. The A-kinase anchoring protein 15 regulates feedback inhibition of the epithelial Na+ channel. FASEB J 2007; 21:1189-201. [PMID: 17244820 DOI: 10.1096/fj.06-6046com] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Protein kinase A anchoring proteins or AKAPs regulate the activity of many ion channels. Protein kinase A (PKA) is a well-recognized target of AKAPs, with other kinases now emerging as additional targets. We examined the roles of epithelial-expressed AKAPs in regulating the epithelial Na+ channel (ENaC). Experiments used heterologous expression with AKAP15, AKAP-KL, and AKAP79 in Xenopus oocytes. Experiments were carried out under high and low Na+ conditions, as Na+ loading is known to affect the baseline activity of ENaC in a PKC-dependent mechanism. ENaC activity was unaffected by AKAP79 and AKAP-KL expression. However, oocytes coexpressing AKAP15 exhibited an 80% and 91% reduction in the amiloride-sensitive, whole-cell conductance in high and low Na+ conditions, respectively. The reduced channel activity was unaffected by PKA activation or inhibition, indicating a PKA-independent mechanism. Expression with a membrane-targeting domain, mutant form of AKAP15 (AKAP15m) prevented the decrease of ENaC activity, but only under low Na+ conditions. In high sodium conditions, coexpression with AKAP15m led to an increase of ENaC activity to levels similar to those observed under low Na+. These results indicate that membrane-associated AKAP15 reduces ENaC activity whereas the cytoplasmically associated one may participate in the channel's feedback inhibition by intracellular Na+, a process known to involve PKC. This hypothesis was further confirmed in coexpression experiments, which demonstrated functional and physical interaction between AKAP15 and PKCalpha. We propose that AKAP15 regulates ENaC via a novel PKA-independent pathway.
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Affiliation(s)
- Abderrahmane Bengrine
- Department of Physiology and Biophysics, SUNY at Buffalo, 3435 Main St., Buffalo, NY 14214, USA
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142
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Zhao Q, Fan Z, He J, Chen S, Li H, Zhang P, Wang L, Hu D, Huang J, Qiang B, Gu D. Renalase gene is a novel susceptibility gene for essential hypertension: a two-stage association study in northern Han Chinese population. J Mol Med (Berl) 2007; 85:877-85. [PMID: 17216203 DOI: 10.1007/s00109-006-0151-4] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2006] [Revised: 09/19/2006] [Accepted: 11/02/2006] [Indexed: 11/28/2022]
Abstract
Renalase, a novel flavin adenine dinucleotide-dependent amine oxidase, is secreted by the kidney, degrades circulating catecholamines, and modulates cardiac function and systemic blood pressure (BP). Its discovery may provide novel insights into the mechanisms of BP regulation and the pathogenesis of essential hypertension (EH). We designed a two-stage case-control study to investigate whether the renalase gene harbored any genetic variants associated with EH in the northern Han Chinese population. From the International Collaborative Study of Cardiovascular Disease in Asia (InterASIA in China), 1,317 hypertensive cases and 1,269 normotensive controls were recruited. These total 2,586 subjects were taken as the main study population in this study. In stage 1, all the eight selected single nucleotide polymorphisms (SNPs) of the renalase gene were genotyped and tested within a subsample (503 cases and 490 controls) of the main study population. By single locus analyses, three SNPs, rs2576178, rs2296545, and rs2114406, showed significant associations with EH (P < 0.05). In stage 2, these three SNPs were genotyped on the remaining individuals and analyzed using all the individuals. After Bonferroni correction for multiple comparisons, the associations of rs2576178 and rs2296545 with EH were still significant in stage 2. The cases had higher frequencies of rs2576178 G allele and rs2296545 C allele than the controls (0.55 versus 0.49, P < 0.0001; 0.61 versus 0.55, P < 0.0001). Particularly, under the codominant model, the adjusted odds ratios for rs2576178 GG genotype and rs2296545 CC genotype were 1.58 (95% CI, 1.25 to 2.00; P = 0.0002) and 1.61 (95% CI, 1.26 to 2.04; P = 0.0002), respectively. We also found risk-associated haplotypes and diplotypes, which further confirmed the significant association between the renalase gene and EH. These findings may provide novel genetic susceptibility markers for EH and lead to a better understanding of EH pathophysiology. In addition, further replications in other populations and functional studies would be warranted.
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Affiliation(s)
- Qi Zhao
- Department of Evidence Based Medicine and Division of Population Genetics, Cardiovascular Institute and Fuwai Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
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143
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Huang DY, Boini KM, Osswald H, Friedrich B, Artunc F, Ullrich S, Rajamanickam J, Palmada M, Wulff P, Kuhl D, Vallon V, Lang F. Resistance of mice lacking the serum- and glucocorticoid-inducible kinase SGK1 against salt-sensitive hypertension induced by a high-fat diet. Am J Physiol Renal Physiol 2006; 291:F1264-73. [PMID: 17003223 DOI: 10.1152/ajprenal.00299.2005] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Mineralocorticoids enhance expression and insulin stimulates activity of the serum- and glucocorticoid-inducible kinase SGK1, which activates the renal epithelial Na+ channel (ENaC). Under a salt-deficient diet, SGK1 knockout mice ( sgk1−/−) excrete significantly more NaCl than their wild-type littermates ( sgk1 +/+) and become hypotensive. The present experiments explored whether SGK1 participates in the hypertensive effects of a high-fat diet and high-salt intake. Renal SGK1 protein abundance of sgk1 +/+ mice was significantly elevated after a high-fat diet. Under a control diet, fluid intake, blood pressure, urinary flow rate, and urinary Na+, K+, and Cl− excretion were similar in sgk1−/− and sgk1 +/+ mice. Under a standard diet, high salt (1% NaCl in the drinking water for 25 days) increased fluid intake, urinary flow rate, and urinary Na+, K+, and Cl− excretion similarly in sgk1−/− and sgk1 +/+ mice without significantly altering blood pressure. A high-fat diet alone (17 wk) did not significantly alter fluid intake, urinary flow rate, urinary Na+, K+, or Cl− excretion, or plasma aldosterone levels but increased plasma insulin, total cholesterol, triglyceride concentrations, and systolic blood pressure to the same extent in both genotypes. Additional salt intake (1% NaCl in the drinking water for 25 days) on top of a high-fat diet did not affect hyperinsulinemia or hyperlipidemia but increased fluid intake, urinary flow rate, and urinary NaCl excretion significantly more in sgk1−/− than in sgk1 +/+mice. Furthermore, in animals receiving a high-fat diet, additional salt intake increased blood pressure only in sgk1 +/+ mice (to 132 ± 3 mmHg) but not in sgk1−/− mice (120 ± 4 mmHg). Thus lack of SGK1 protects against the hypertensive effects of a combined high-fat/high-salt diet.
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Affiliation(s)
- Dan Yang Huang
- Department of Pharmacology, University of Tübingen, Gmelinstr. 5, D-72076 Tübingen, Germany
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144
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Abstract
The post-macula densa segments of the renal tubule--that is, the distal convoluted tubule, connecting tubule, and collecting duct--play a central role in determining final urine sodium excretion. The major regulated sodium transporters and channels in these cell types include the thiazide-sensitive (Na-Cl) cotransporter (NCC), the epithelial sodium channel (ENaC), and Na-K-ATPase. Furthermore, although not involved in sodium reabsorption, the anion exchanger, pendrin, and the basolateral bumetanide-sensitive Na-K-2Cl cotransporter (NKCC1 or BSC2) have roles in blood-volume maintenance. Mutations in several of these major sodium transporters, channel subunits, and their regulatory proteins have been linked to human diseases such as Liddle's syndrome, Gitelman's syndrome, and Gordon's syndrome, emphasizing the need for appropriate regulation of sodium at these sites for maintenance of sodium balance and normotension.
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Affiliation(s)
- Carolyn A Ecelbarger
- Department of Medicine, Georgetown University, Box 571412, Washington, DC 20057-1412, USA.
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145
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Abstract
QTL mapping in humans and rats has identified hundreds of blood-pressure-related phenotypes and genomic regions; the next daunting task is gene identification and validation. The development of novel rat model systems that mimic many elements of the human disease, coupled with advances in the genomic and informatic infrastructure for rats, promise to revolutionize the hunt for genes that determine susceptibility to hypertension. Furthermore, methods are evolving that should enable the identification of candidate genes in human populations. Together with the computational reconstruction of regulatory networks, these methods provide opportunities to significantly advance our understanding of the underlying aetiology of hypertension.
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Affiliation(s)
- Allen W Cowley
- Department of Physiology, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, Wisconsin 53226, USA.
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146
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He FJ, MacGregor GA. Importance of salt in determining blood pressure in children: meta-analysis of controlled trials. Hypertension 2006; 48:861-9. [PMID: 17000923 DOI: 10.1161/01.hyp.0000245672.27270.4a] [Citation(s) in RCA: 255] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
To assess the effect of reducing salt intake on blood pressure in children, we carried out a meta-analysis of controlled trials. Trials were included if participants were children (< or = 18 years), and duration of salt reduction must have been for > or = 2 weeks. Mean effect size was calculated using a fixed-effect model, because there was no significant heterogeneity. Ten trials of children and adolescents with 966 participants were included (median age: 13 years; range: 8 to 16 years; median duration: 4 weeks; range: 2 weeks to 3 years). Salt intake was reduced by 42% (interquartile range [IQR]: 7% to 58%). There were significant reductions in blood pressure: systolic: -1.17 mm Hg (95% CI: -1.78 to -0.56 mm Hg; P<0.001); diastolic: -1.29 mm Hg (95% CI: -1.94 to -0.65 mm Hg; P<0.0001). Three trials of infants with 551 participants were included (median duration: 20 weeks; range: 8 weeks to 6 months). Salt intake was reduced by 54% (IQR: 51% to 79%). There was a significant reduction in systolic blood pressure: -2.47 mm Hg (95% CI: -4.00 to -0.94 mm Hg; P<0.01). This is the first meta-analysis of salt reduction in children, and it demonstrates that a modest reduction in salt intake causes immediate falls in blood pressure and, if continued, may well lessen the subsequent rise in blood pressure with age. This would result in major reductions in cardiovascular disease. These results in conjunction with other evidence provide strong support for a reduction in salt intake in children.
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Affiliation(s)
- Feng J He
- Blood Pressure Unit, Cardiac and Vascular Sciences, St George's University of London, Cranmer Terrace, London, SW17 0RE, United Kingdom.
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147
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Feig DI, Rodriguez-Iturbe B, Nakagawa T, Johnson RJ. Nephron Number, Uric Acid, and Renal Microvascular Disease in the Pathogenesis of Essential Hypertension. Hypertension 2006; 48:25-6. [PMID: 16682608 DOI: 10.1161/01.hyp.0000223447.53155.d5] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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148
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Abstract
Hypertension is most often considered a disease of old age, but the precursors are often present in young children long before the clinically accepted definitions of hypertension in the adult are manifested. Essential hypertension is by far the most common form of the disease, comprising a complex interaction of genetic and environmental factors. Many individual genes that play a role in the maintenance of blood pressure have been identified; however, none has been shown specifically to be a component of essential hypertension. Hypertension is among the leading risk factors for coronary heart disease, stroke, and end-stage renal disease, making it critically important to identify individuals at risk early in life prior to manifestation of clinical signs and symptoms.
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Affiliation(s)
- John Edward Jones
- Department of Pediatrics and Physiology and Biophysics, Georgetown University Medical Center, F2004 PHC, 4000 Reservoir Road NW, Washington, DC 20057, USA
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149
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Song J, Hu X, Riazi S, Tiwari S, Wade JB, Ecelbarger CA. Regulation of blood pressure, the epithelial sodium channel (ENaC), and other key renal sodium transporters by chronic insulin infusion in rats. Am J Physiol Renal Physiol 2006; 290:F1055-64. [PMID: 16303859 DOI: 10.1152/ajprenal.00108.2005] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
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 (∼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 (α, β, and γ) 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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Affiliation(s)
- Jian Song
- Division of Endocrinology and Metabolism, Department of Medicine, Georgetown Univ., 4000 Reservoir Rd. 233 NW, Washington, DC 20057-1412, USA
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150
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Abstract
This review summarizes recent information concerning the pharmacological and toxicological significance of the human flavin-containing monooxygenase (FMO, EC 1.14.13.8). The human FMO oxygenates nucleophilic heteroatom-containing chemicals and drugs and generally converts them into harmless, polar, readily excreted metabolites. Sometimes, however, FMO bioactivates chemicals into reactive materials that can cause toxicity. Most of the interindividual differences of FMO are due to genetic variability and allelic variation, and splicing variants may contribute to interindividual and interethnic variability observed for FMO-mediated metabolism. In contrast to cytochrome P450 (CYP), FMO is not easily induced nor readily inhibited, and potential adverse drug-drug interactions are minimized for drugs prominently metabolized by FMO. These properties may provide advantages in drug design and discovery, and by incorporating FMO detoxication pathways into drug candidates, more drug-like materials may be forthcoming. Although exhaustive examples are not available, physiological factors can influence FMO function, and this may have implications for the clinical significance of FMO and a role in human disease.
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Affiliation(s)
- John R Cashman
- Human BioMolecular Research Institute, San Diego, CA 92121, USA.
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