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Polymorphism affecting water balance

多态性影响水平衡

基本信息

批准号：
7927715
负责人：
DAVID M COHEN
金额：
--
依托单位：
PORTLAND VA MEDICAL CENTER
依托单位国家：
美国
项目类别：
财政年份：
2010
资助国家：
美国
起止时间：
2010-07-01 至 2014-06-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/7927715
关键词：
Accounting Acids Address Adverse effects Affect Alleles Amino Acids Animal Model Animals Antidepressive Agents Antipsychotic Agents Back Biological Assay Blood Chemical Analysis Body Water Cations Caucasians Caucasoid Race Chronic Chronically Ill Clinical Code Cognition Complex Controlled Study DNA Data Data Set Disease Diuretics Elderly Electrolytes Equilibrium Ethnic Origin Excretory function Exhibits Exons Family Genes Genetic Genetic Markers Genetic Polymorphism Genomics Genotype Germ Lines Haplotypes Heart Heredity Human Hypernatremia Hyponatremia Hypothalamic structure In Vitro Individual Individual Differences Injection of therapeutic agent Intervention Introns Investigation Ion Channel Knock-in Mouse Life Link Linkage Disequilibrium Mediating Mediator of activation protein Medical Metabolism Minority Modeling Mus Mutation Not Hispanic or Latino Organism Osmoregulation Patients Pharmaceutical Preparations Phase Phenotype Physiological Population Population Study Predisposing Factor Predisposition Prevalence Process Property Proteins RNA Splicing Regulation Regulator Genes Reporter Genes Risk Role Series Serum Severities Signal Transduction Single Nucleotide Polymorphism Sodium Spliced Genes Stress System Testing Transgenic Organisms Tube Variant Veterans Water Water consumption Wild Type Mouse analog animal data arachidonate base blastocyst case-based cohort collecting tubule structure design embryonic stem cell falls genetic regulatory protein homologous recombination human data human subject in vitro testing in vivo indexing lipid mediator member mouse model outcome forecast promoter receptor recombinase response sensor transmission process vector

项目摘要

DESCRIPTION (provided by applicant): Disorders of water balance (i.e., hypernatremia and hyponatremia) are the most frequently encountered of the electrolyte problems; they are exceedingly common among the elderly, the acutely and chronically ill, and among patients taking certain diuretic and anti-depressant medications. All of these predisposing factors are present in a high percentage of patients served by the Department of Veterans Affairs. Aberrant water balance further complicates many chronic medical conditions and confers a poor prognosis independent of the severity of the underlying illness. Recent data from well-controlled studies indicate that even subtle abnormalities in systemic water balance can seriously affect coordination and cognition, and the propensity to falls. Regulation of body water balance is a complex process coordinated by the hypothalamus and executed by the kidney collecting duct; however, the central sensors of systemic tonicity had remained obscure. Recently, members of the transient receptor potential family of cation channels were proposed to serve this role, based upon extensive in vitro data and animal studies. We reasoned that a common single- nucleotide polymorphism in one of these genes may account for individual differences in systemic water balance among healthy elderly human subjects. We identified one such polymorphism in a key water- regulatory gene that confers an amino acid change and results in a protein with aberrant function in vitro. Importantly, we found that the presence of this polymorphism is strongly associated with hyponatremia in two healthy human populations. Furthermore, the effect size is large: the risk of hyponatremia is more than doubled by the presence of a single copy of this allele. To cement this relationship, we propose three experimental aims. In Aim I, we will sequence the haplotype block in which this polymorphism is embedded, to establish that no other polymorphism in tight linkage disequilibrium with our known variant accounts for the effect of this allele. Although we strongly suspect that this is the case, based upon our sequencing of all coding exons and splice junctions in this block, a robust conclusion requires phasing the entire haplotype block. This will also aid our investigation of multiple ethnicities. In Aim II, we will test additional large human populations for the presence of this polymorphism to confirm its association with serum sodium concentration and with hyponatremia. In Aim III, we will test for the role of epoxyeicosatrienoic acid signaling in systemic water balance in normal mice. Second, we will "knock in" the variant allele of the water-regulatory gene in a mouse model to test if it can independently recapitulate the human hyponatremic phenotype. We further propose to apply a number of physiological maneuvers to unmask a latent water-retentive phenotype. There is extremely high conservation between the human and mouse gene, including the amino acid affected by this polymorphism and its immediate context. Of note, we will not create a transgenic harboring an "extra" allele with this polymorphism; we will replace one or both wild-type alleles with a murine analog of this variant allele. In addition, in this Aim we will test the role of the epoxyeicosatrienoic acid system in regulating systemic water balance, in both wild-type and knock-in mice. There are no data addressing the role of this system in water balance in vivo, although it mediates tonicity-sensing by central osmosensing channels and we now show in our preliminary data that this effect is interrupted by our key polymorphism. PUBLIC HEALTH RELEVANCE: Disorders of water balance are among the most frequently encountered and morbid of the blood chemistry problems; they are exceedingly common among the elderly, the acutely and chronically ill, and among patients taking certain diuretic and anti-depressant medications. All of these predisposing factors are present in a high percentage of patients served by the Department of Veterans Affairs. We show that a common genetic change in a key water-regulatory protein increases the risk of developing improper water balance. We aim to understand how this genetic change increases the risk of water imbalance through a series of investigations in the test-tube, through a range of studies in animal models, and through analyses of human data and genomic DNA.

描述（由申请人提供）：