GORDON'S SYNDROME AND THE GENETICS OF SODIUM CHLORIDE TRANSPORT

戈登综合征和氯化钠转运的遗传学

• 批准号: 6302411
• 负责人: DAVID H ELLISON
• 金额: $ 10.91万
• 依托单位: YALE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-03-16 至 2001-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6302411
• 关键词: Xenopus oocyte; aldosterone; amiloride; autosomal dominant trait; clinical research; familial hypertension; family genetics; gene mutation; hormone regulation /control mechanism; human subject; immunocytochemistry; in situ hybridization; ion transport; laboratory mouse; linkage mapping; mineralocorticoids; molecular cloning; molecular genetics; northern blottings; polymerase chain reaction; protein kinase C; renal tubular transport; sodium channel; sodium chloride; thiazide

This project describes experiments designed to test the hypothesis that a mutation in the gene encoding the thiazide-sensitive Na-Cl cotransporter is the molecular basis of Gordon's syndrome (GS). Gordon's syndrome is an autosomal dominant form of hypertension associated with hyperkalemia, renal tubular acidosis, and normal renal function. Shambelan postulated that this syndrome was caused by a "chloride shunt" in the distal nephron. According to this hypothesis, the distal nephron would be transformed from a segment that reabsorbed Na in exchange for K and H to one that reabsorbed Na primarily with Cl. The predominant Na and Cl reabsorptive pathway of the mammalian distal tubule is a thiazide-sensitive Na-Cl cotransporter. Interestingly, most signs of GS are remarkably sensitive to treatment with low doses of thiazide diuretics. Thus, the thiazide- sensitive Na-Cl cotransporter is an excellent candidate gene for GS. A mutation in the thiazide-sensitive Na-Cl transporter causing GS would constitutively activate the transport protein. This transport protein was recently cloned from the bladder of the Winter Flounder and from mammals. The message for this protein is expressed in distal convoluted tubule cells and connecting tubule cells in humans. Up regulation of thiazide- sensitive Na-Cl cotransport in the connecting tubule could explain all of the clinical features of Gordon's syndrome. We have screened a cosmid library with a mammalian thiazide-sensitive transporter clone, identified four clones, and identified a polymorphic GT repeat motif within this region on chromosome 16. The aims of this project are to, l) clarify the nephron distribution of the thiazide-sensitive Na-Cl cotransporter, the bumetanide-sensitive Na-K- 2Cl cotransporter and the amiloride-sensitive Na channel in the mammalian distal nephron, 2) identify specific regulators of thiazide-sensitive Na- Cl cotransport in vitro, 3) test the hypothesis that Gordon's syndrome is linked to the thiazide-sensitive Na-Cl cotransporter gene, 4) identify the specific mutation responsible for Gordon's syndrome, and 5) express normal and mutated ion transporters in Xenopus oocytes and mammalian cell lines to screen for functional differences in transporter activity and regulatory control. The results of these studies will identify the genetic basis and the molecular physiology of an important Mendelian form of hypertension and lead to tools for both screening and treatment. The results should also provide clues to the pathogenesis of essential hypertension especially in volume dependent patients.

该项目描述了旨在检验以下假设的实验： 编码噻嗪类敏感的 Na-Cl 协同转运蛋白的基因发生突变 是戈登氏综合症（GS）的分子基础。戈登氏综合症是一种 与高钾血症相关的常染色体显性高血压， 肾小管性酸中毒，肾功能正常。香贝兰假设 该综合征是由远端肾单位的“氯分流”引起的。 根据这一假设，远端肾单位将由 重吸收 Na 以换取 K 和 H 的片段 主要用Cl重吸收Na。 Na 和 Cl 重吸收占主导地位 哺乳动物远曲小管的通路是噻嗪类敏感的 Na-Cl 协同转运蛋白。有趣的是，大多数 GS 症状都对 用小剂量噻嗪类利尿剂治疗。因此，噻嗪类 敏感的Na-Cl协同转运蛋白是GS的一个极好的候选基因。一个 噻嗪类敏感的 Na-Cl 转运蛋白突变会导致 GS 组成型激活转运蛋白。这种转运蛋白是 最近从冬鲽鱼的膀胱和哺乳动物中克隆出来。 该蛋白质的信息在远曲小管中表达 细胞和人体连接小管细胞。噻嗪类的上调- 连接小管中敏感的 Na-Cl 共转运可以解释所有 戈登综合征的临床特征。我们筛选了一个粘粒 鉴定出具有哺乳动物噻嗪类敏感转运蛋白克隆的文库 四个克隆，并在其中鉴定出多态性 GT 重复基序 16号染色体上的区域。 该项目的目的是，l) 阐明肾单位的分布 噻嗪类敏感的 Na-Cl 协同转运蛋白、布美他尼类敏感的 Na-K- 哺乳动物中的 2Cl 协同转运蛋白和阿米洛利敏感的 Na 通道 远端肾单位，2) 识别噻嗪类敏感 Na- 的特定调节因子 Cl 体外共转运，3) 检验戈登综合征是 与噻嗪类敏感的 Na-Cl 协同转运蛋白基因相连，4) 鉴定 导致戈登综合征的特定突变，以及 5) 表达正常 爪蟾卵母细胞和哺乳动物细胞系中的突变离子转运蛋白 筛选转运蛋白活性的功能差异 监管控制。这些研究的结果将确定遗传 重要孟德尔形式的基础和分子生理学 高血压并导致筛查和治疗工具的出现。这 结果还应为重要的发病机制提供线索 高血压，尤其是容量依赖性患者。