H+-ATPase B-subunit Dysfunction and Calcium Nephrolithiasis

H-ATP酶 B 亚基功能障碍和钙肾结石

• 批准号: 7930519
• 负责人: Orson W Moe
• 金额: $ 39.25万
• 依托单位: UT SOUTHWESTERN MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-09-15 至 2011-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7930519
• 关键词: ATP Hydrolysis; ATP phosphohydrolase; Address; Aldehyde-Lyases; Alleles; Anions; Binding; Biochemical; Biochemistry; Biology; Calcium; Calcium Oxalate; Calculi; Candidate Disease Gene; Carbonic Anhydrase II; Carrier State; Cataloging; Catalogs; Cells; Cellular biology; Chemicals; Chemistry; Clinical; Clinical Data; Code; Complex; Coupling; Data; Databases; Defect; Diagnosis; Disease; Distal renal tubular acidosis Type 1; Face; Family member; Foundations; Frequencies; Functional disorder; Gene Frequency; General Population; Genes; Genetic; Genetic Variation; Genotype; Gray unit of radiation dose; Heterozygote; Human; Hydrolysis; In Vitro; Individual; Inheritance Patterns; Inherited; Inpatients; Kidney; Kidney Calculi; Kidney Diseases; Laboratory Study; Low Prevalence; Mammalian Cell; Metabolic; Molecular; Mutation; Nephrolithiasis; Oxalates; Patients; Persons; Phenotype; Physiology; Plasma; Point Mutation; Polygenic Traits; Population; Predisposition; Process; Protein Biochemistry; Proteins; Proton Pump; Proton-Translocating ATPases; Pump; Risk; Risk Factors; Structure; System; Testing; Urine; Variant; Work; Yeasts; base; calcium phosphate; cohort; genetic variant; high risk; human data; hypercalciuria; inhibitor/antagonist; medical attention; mutant; population based; public health relevance; reconstitution; research study; vacuolar H+-ATPase

DESCRIPTION (provided by applicant): The hereditary component of nephrolithiasis is a complex polygenic trait which is a formidable challenge to unravel. The study of monogenic causes of nephrolithiasis has been most informative in uncovering genetic components of nephrolithiasis. Calcareous stones are common in patients with congenital distal renal tubular acidosis :dRTA; but sd RcoTnAs idered a very rare cause of calcium stones due to the low prevalence of the disease. Congenital dRTA is a disease of renal acidification caused by mutations in either the vacuolar :VPa;se-A T :B1 or a4 subunit;, anion exchanger-1, or carbonic anhydrase II. This proposal focuses on the B1 subunit of the V-ATPase. The heterozygous carrier state is universaly believed to be silent. The mechanisms by which a mutant B1 subunit cause pump dysfunction is not well understood. We will test 3 hypotheses in this proposal: I. Heterozygous mutations of B1 are not rare in the stone forming population. II. The burden of heterozygosity is not silent but confers propensity for or affliction by calcium phosphate or oxalate nephrolithiasis. III. Mutant B1 subunits cause pump dysfunction by multiple mechanisms such as defective pump assembly, impaired ATP binding/hydrolysis, and deranged coupling to HE translocation. We will test these hypotheses with 3 Aims: 1. Population-based studies: Define the allele frequency of all base changes in B1 in the stone forming and non-stone forming population and collect the corresponding clinical data of these individuals. 2. Inpatient human studies: Perform detailed metabolic and physicochemical studies of selected individuals heterozygous for B1 to characterize their phenotype. 3. Bench studies: Define the mechanisms of how various mutant B1 subunits cause HE pump dysfunction using cell biology and biochemistry. This is not a study of classical dRTA. Instead we may be able to prove that monogenic predisposition is actually not rare in the general stone-forming population and many stone formers may harbor B1 mutations that predispose them to calcium stones. This may set precedence, for other monogenic predispositions in the general stone forming population. These studies will also significantly advance the understanding of V-ATPase biology. These natural point mutations and their cognate mode of dysfunction will provide valuable structure-function information on the biology of the B1 protein. PUBLIC HEALTH RELEVANCE: Each human has a 10-20% chance of getting a kidney stone in his or her lifetime. If a person has a family member with kidney stones, that individual has a higher risk of getting kidney stones. This process can involve many genes but there are circumstances where single genes can put a person at risk for kidney stones such as in a condition is distal renal tubular acidosis (abbreviated as dRTA). Most patients with dRTA get calcium kidney stones, but most patients with calcium kidney stones do not have dRTA. This proposal examines some new ideas. Based on our work in the last year, we believe that a milder form of dRTA where one inherits one instead of two defective genes, termed "heterozygous state" may be quite common in the general population of calcium kidney stones formers. The gene in question codes for a protein called "B1" which in its abnormal state will change the composition in the urine resulting in kidney stone formation. We will use human population and laboratory studies to answer three questions. 1. Exactly how common are abnormal B1 in a heterozygous state in people with calcium kidney stones? 2. If one carries an abnormal copy of B1 (the heterozygous state), what exactly are the abnormalities in the urine that predispose that person to having kidney stones? 3. How does an abnormal B1 change the composition of our urine so kidney stones will form? These questions, when answered, help us understand the hereditary component of kidneys stones and how abnormalities in single proteins, such as B1, will change our urine composition in an unfavorable way allowing allow us to better predict, diagnose, and treat kidney stones.

描述(申请人提供)：肾结石的遗传成分是一个复杂的多基因特征，这是一个巨大的挑战来解开。对肾结石的单基因病因的研究在揭示肾结石的遗传成分方面具有最大的信息量。钙质结石在先天性远端肾小管酸中毒患者中很常见：DRTA；但SD RcoTnas是一种非常罕见的钙结石原因，因为该病的患病率很低。先天性DRTA是一种肾脏酸化疾病，由空泡：VPA、Se-A、T：B1或A4亚基、阴离子交换器-1或碳酸氢酶II突变引起。本研究重点介绍V-ATPase的B1亚基。杂合载流子状态通常被认为是沉默的。突变的B1亚基导致泵功能障碍的机制还不是很清楚。在这项建议中，我们将检验3个假设：1.B1杂合突变在结石形成人群中并不少见。杂合子的负担并不是沉默的，而是使人容易患上磷酸钙或草酸盐型肾结石。突变的B1亚基通过多种机制导致泵功能障碍，如泵组装缺陷、ATP结合/水解性受损以及与HE易位的错配。我们将通过三个目标来验证这些假说：1.基于人群的研究：定义结石形成和非结石形成人群中B1碱基变化的等位基因频率，并收集这些个体的相应临床数据。2.住院人类研究：对选定的B1杂合子个体进行详细的代谢和理化研究，以确定他们的表型。3.台架研究：利用细胞生物学和生物化学的方法，确定各种突变的B1亚基是如何导致HE泵功能障碍的机制。这不是对经典dRTA的研究。相反，我们可能能够证明，单基因易感性实际上在普通结石形成人群中并不罕见，许多结石形成者可能含有B1突变，使他们容易患上钙结石。这可能会为普通成石人群中的其他单基因易感基因设定优先顺序。这些研究也将极大地促进对V-ATPase生物学的理解。这些自然点突变及其相关的功能障碍模式将为B1蛋白的生物学提供有价值的结构-功能信息。与公共健康相关：每个人在有生之年患肾结石的几率为10%-20%。如果一个人的家庭成员患有肾结石，那么这个人患肾结石的风险就更高。这一过程可能涉及许多基因，但在某些情况下，单基因可能会使人面临患肾结石的风险，例如，在远端肾小管酸中毒(简称dRTA)的情况下。大多数DRTA患者患有钙质肾结石，但大多数钙质肾结石患者没有DRTA。这项提议考察了一些新的想法。根据我们去年的工作，我们认为，一种较轻微的dRTA形式，即一个人遗传一个而不是两个缺陷基因，被称为“杂合子状态”，可能在钙质肾结石患者的普通人群中相当常见。该基因编码一种名为“B1”的蛋白质，在其异常状态下，它会改变尿液中的成分，导致肾结石的形成。我们将使用人口和实验室研究来回答三个问题。1.在钙肾结石患者中，处于杂合子状态的异常B1到底有多常见？2.如果一个人携带了异常的B1(杂合子状态)，那么尿液中的异常是什么使他容易患上肾结石？3.异常的B1是如何改变我们尿液的成分从而形成肾结石的？这些问题的答案有助于我们了解肾结石的遗传成分，以及单一蛋白(如B1)的异常如何以不利的方式改变我们的尿液成分，从而使我们能够更好地预测、诊断和治疗肾结石。