Polymorphism affecting water balance

多态性影响水平衡

• 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
• 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

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）： 水平衡疾病（即高钠血症和低钠血症）是电解质问题最常遇到的。它们在老年人，急性和慢性病中以及服用某些利尿剂和抗抑郁药的患者中非常普遍。所有这些诱人的因素都存在于退伍军人事务部服务的很大比例的患者中。异常水平的平衡进一步使许多慢性医疗状况复杂化，并赋予预后不佳，而与潜在疾病的严重程度无关。来自良好控制的研究的最新数据表明，即使是全身水平衡的微妙异常也会严重影响协调和认知，以及跌倒的倾向。人体水平的调节是由下丘脑协调的复杂过程，并由肾脏收集管道执行。但是，全身性能的中央传感器仍然晦涩难懂。最近，根据广泛的体外数据和动物研究，提出了临时受体潜在的阳离子通道势家族的成员来发挥这种作用。我们认为，其中一个基因中的一个常见的单核苷酸多态性可能解释了健康的老年人类受试者的全身水平衡的个体差异。我们在关键水调节基因中确定了一种这种多态性，该基因赋予氨基酸变化并导致体外具有异常功能的蛋白质。重要的是，我们发现这种多态性的存在与两个健康人群中低钠血症密切相关。此外，效果大小很大：由于存在该等位基因的单个副本，低钠血症的风险翻了一番。为了巩固这种关系，我们提出了三个实验目标。在AIM I中，我们将对这种多态性嵌入的单倍型块进行测序，以确定在紧密的连锁中没有其他多态性与我们已知的变体有关该等位基因的影响。尽管我们强烈怀疑是这种情况，但基于我们对该块中所有编码外显子和剪接连接的测序，鲁棒的结论需要逐步缩小整个单倍型块。这也将有助于我们对多种种族的调查。在AIM II中，我们将测试其他大型人群，以确认其与血清钠浓度和低钠血症的关联。在AIM III中，我们将测试环氧钠酸信号传导在正常小鼠全身水平衡中的作用。其次，我们将在小鼠模型中“敲击”水调节基因的变体等位基因，以测试它是否可以独立地概括人类低钠表型。我们进一步建议采用许多生理操作来揭示潜在的退水表型。人类基因和小鼠基因之间的保守性极高，包括受该多态性影响的氨基酸及其直接情况。值得注意的是，我们不会创建具有这种多态性的“额外”等位基因的转基因。我们将用该变体等位基因的鼠类似物代替一个或两个野生型等位基因。此外，在此目的中，我们将测试环氧钙卫星酸系统在调节野生型和敲门小鼠中的全身水平衡中的作用。没有数据解决该系统在体内水平上的作用，尽管它通过中央渗透传感器介导了张力感，我们现在在初步数据中表明，这种效果被我们的关键多态性中断。 公共卫生相关性： 水平衡疾病是血液化学问题最常遇到的和病态的。它们在老年人，急性和慢性病中以及服用某些利尿剂和抗抑郁药的患者中非常普遍。所有这些诱人的因素都存在于退伍军人事务部服务的很大比例的患者中。我们表明，关键水调节蛋白的常见遗传变化增加了发展不当水平的风险。我们旨在了解这种遗传变化如何通过测试管中的一系列研究，通过动物模型中的一系列研究以及对人类数据和基因组DNA的分析来增加水失衡的风险。