Polymorphism affecting water balance

多态性影响水平衡

基本信息

批准号：
8394605
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/8394605
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.

描述（由申请人提供）：水平衡紊乱（即高钠血症和低钠血症）是最常见的电解质问题；它们在老年人、急性和慢性病患者以及服用某些利尿剂和抗抑郁药物的患者中极为常见。所有这些诱发因素在退伍军人事务部服务的患者中都存在很高比例。水平衡异常使许多慢性疾病进一步复杂化，并导致预后不良，与潜在疾病的严重程度无关。来自严格控制的研究的最新数据表明，即使是全身水平衡的细微异常也会严重影响协调性和认知以及跌倒的倾向。体内水平衡的调节是一个复杂的过程，由下丘脑协调并由肾集合管执行。然而，全身张力的中心传感器仍然不清楚。最近，根据大量的体外数据和动物研究，提出了阳离子通道瞬时受体电位家族的成员来发挥这一作用。我们推断，这些基因之一的常见单核苷酸多态性可能解释了健康老年人受试者全身水平衡的个体差异。我们在一个关键的水调节基因中发现了一个这样的多态性，它会导致氨基酸变化并导致体外功能异常的蛋白质。重要的是，我们发现这种多态性的存在与两个健康人群的低钠血症密切相关。此外，效应大小很大：该等位基因单个拷贝的存在使低钠血症的风险增加一倍以上。为了巩固这种关系，我们提出了三个实验目标。在目标 I 中，我们将对嵌入该多态性的单倍型块进行测序，以确定与我们已知的变体紧密连锁不平衡的其他多态性不会解释该等位基因的影响。尽管我们强烈怀疑情况确实如此，但根据我们对该块中所有编码外显子和剪接点的测序，一个可靠的结论需要对整个单倍型块进行定相。这也将有助于我们对多个种族的调查。在目标 II 中，我们将测试更多的大型人群是否存在这种多态性，以确认其与血清钠浓度和低钠血症的关联。在目标 III 中，我们将测试环氧二十碳三烯酸信号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“敲入”水调节基因的变异等位基因，以测试它是否可以独立地重现人类低钠表型。我们进一步建议应用一些生理策略来揭示潜在的保水表型。人类和小鼠基因之间存在极高的保守性，包括受这种多态性及其直接背景影响的氨基酸。值得注意的是，我们不会创建带有这种多态性的“额外”等位基因的转基因；我们将用该变异等位基因的鼠类似物替换一个或两个野生型等位基因。此外，在这个目标中，我们将测试环氧二十碳三烯酸系统在野生型和敲入小鼠中调节全身水平衡的作用。尽管该系统通过中央渗透感应通道介导张力感应，但没有数据说明该系统在体内水平衡中的作用，并且我们现在在初步数据中表明，这种作用被我们的关键多态性中断。