Role of claudin-2 in Calcium Homeostasis and Kidney Stone Disease

Claudin-2 在钙稳态和肾结石疾病中的作用

基本信息

批准号：
10238078
负责人：
Alan S Yu
金额：
$ 31.08万
依托单位：
UNIVERSITY OF KANSAS MEDICAL CENTER
依托单位国家：
美国
项目类别：
财政年份：
2019
资助国家：
美国
起止时间：
2019-09-18 至 2024-08-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/10238078
关键词：
Affect Attention Back Biological Assay Calcium Cations Colon Crystallization Data Defect Deposition Development Disease Distal Frequencies Gene Proteins Genes Genetic Polymorphism Genotype Goals Henle&apos s loop Homeostasis Human Intercellular Junctions Intestinal Secretions Intestines Ion Channel Kidney Kidney Calculi Knockout Mice Lead Limb structure Lithium Mediating Micropuncture Modeling Mus Nature Nephrocalcinosis Nephrolithiasis Papillary Pathogenesis Pathogenicity Pathway interactions Patients Permeability Phenotype Population Preparation Proteins Proximal Kidney Tubules Recording of previous events Renal tubule structure Risk Risk Factors Role Route Site Testing Thinness Tight Junctions Tissues Tracer Urinary Calculi Urine Western Blotting calcium excretion cohort conditional knockout exosome genetic variant hypercalciuria insight intestinal epithelium novel novel therapeutic intervention novel therapeutics population based protein expression radiotracer renal calcium sex thiazide urinary volunteer

项目摘要

PROJECT SUMMARY/ABSTRACT Kidney stones affect 9% of the population and idiopathic hypercalciuria is the major pathogenic risk factor. Our long-term goal is to elucidate the pathogenesis of idiopathic hypercalciuria and develop novel therapies. The renal proximal tubule reabsorbs 70% of filtered calcium, which is believed to occur via the paracellular pathway. Claudin-2 is a paracellular cation channel that is expressed in the proximal renal tubule and in intestinal epithelium. In preliminary studies, we show that claudin-2 knockout mice have renal and absorptive hypercalciuria, leading to severe papillary nephrocalcinosis. Moreover, we find that claudin-2 gene variants are associated with kidney stone disease in humans. We hypothesize that claudin-2 mediates calcium reabsorption in the proximal tubule and calcium secretion in the colon. Loss of claudin-2 increases calcium delivery to the loop of Henle, and predisposes to inner medullary calcium deposition and hence kidney stone disease. The specific aims to test this hypothesis are: (1) Test whether claudin-2 mediates paracellular calcium reabsorption in the renal proximal tubule. We will use tubule micropuncture of claudin-2 global knockout mice, determine the contribution of the proximal tubule with kidney-specific conditional knockout mice, test the role of claudin-2 in the hypocalciuric effect of thiazides, and explore the effect of sex. (2) Test whether claudin-2 mediates intestinal secretion of calcium. We will generate intestine-specific claudin-2 knockout mice and perform tracer flux assays in everted intestinal sacs and Ussing chamber preparations. (3) Test whether human claudin-2 gene variants and protein expression are associated with urine calcium and kidney stones. We will conduct a gene association study in 3 U.S. population-based cohorts to test the association of claudin-2 gene polymorphisms with a history of kidney stones and calcium excretion. In a separate cohort of kidney stone formers and matched normal volunteers, we will test the association of claudin-2 protein abundance in urinary exosomes with hypercalciuric kidney stone disease.

项目概要/摘要肾结石影响 9% 的人口，特发性高钙尿症是主要的致病危险因素。我们的长期目标是阐明特发性高钙尿症的发病机制并开发新的疗法。这肾近端小管重吸收 70% 的滤过钙，据信这是通过细胞旁途径发生的。 Claudin-2 是一种细胞旁阳离子通道，在近端肾小管和肠中表达上皮。在初步研究中，我们表明claudin-2基因敲除小鼠具有肾功能和吸收功能高钙尿症，导致严重的乳头状肾钙质沉着症。此外，我们发现claudin-2基因变异是与人类肾结石疾病有关。我们假设claudin-2介导钙重吸收近端小管中的钙分泌和结肠中的钙分泌。 Claudin-2 的缺失会增加钙的输送亨利袢，容易发生内髓钙沉积，从而导致肾结石疾病。这检验该假设的具体目的是：（1）检验claudin-2是否介导细胞旁钙重吸收在肾近曲小管中。我们将使用claudin-2全基因敲除小鼠的肾小管微穿刺，确定肾特异性条件敲除小鼠近曲小管的贡献，测试claudin-2在噻嗪类药物的低尿钙作用，并探讨性别的影响。 (2)测试claudin-2是否介导肠道钙的分泌。我们将生成肠道特异性 Claudin-2 敲除小鼠并进行示踪通量测定在外翻肠囊和尤斯室制剂中。 (3)检测人claudin-2基因是否变异蛋白质表达与尿钙和肾结石有关。我们将进行基因关联在 3 个美国人群中进行的研究，旨在测试claudin-2基因多态性与病史的关联肾结石和钙排泄。在肾结石形成者和匹配正常人的单独队列中志愿者，我们将测试尿液外泌体中claudin-2蛋白丰度与高钙尿症的关系肾结石疾病。