Renal Physiology of Pendrin

Pendrin 的肾脏生理学

• 批准号: 6781779
• 负责人: SUSAN MARIE WALL
• 金额: $ 29.07万
• 依托单位: EMORY UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-08-01 至 2006-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6781779
• 关键词: acidity /alkalinity; alkalosis; apical membrane; bicarbonates; cellular polarity; genetically modified animals; immunocytochemistry; laboratory mouse; membrane transport proteins; polymerase chain reaction; protein localization; protein structure function; renal tubular transport; tissue /cell culture

The mammalian kidney has a substantial capacity to excrete an alkaline load. For example, rodents given isotonic NaHCO3 in their drinking water develop only a mild metabolic alkalosis despite this huge base load. The kidney's ability to excrete large alkaline loads occurs in part through active HCO3- secretion in the cortical collecting duct (CCD) mediated by apical anion exchange in the B intercalated cell. While apical anion exchange has been characterized functionally in the CCD, the gene product, which mediates this transport process has remained an area of controversy. However the work of our laboratory and that of our collaborators has demonstrated that pendrin, an anion exchanger, localizes to the apical membrane of non-A intercalated cells in rat, human and mouse. Moreover, our laboratory has demonstrated that pendrin mediates secretion of HCO3- in the mouse CCD. Whether this transporter represents the putative apical anion exchanger remains to be tested fully. Development of knockout mice has greatly facilitated the study of the renal physiology of pendrin in vivo. Because there are no specific inhibitors of either pendrin or apical anion exchange available, knockout mice can be exploited as a biological inhibitor and used to test transport characteristics of pendrin in kidney in vitro. Moreover, balance studies using these animals will allow us to determine if these pendrin-deficient mice have a defect in excretion of an alkaline load. Thus, the present proposal will test if pendrin represents the putative anion exchanger of the CCD. Moreover, these studies will contribute to our understanding of the physiological role of this transporter. To answer these questions our laboratory and that of our collaborators will employ balance studies, tubules perfused in vitro, real-time quantitative RT-PCR, immunogold cytochemistry and immunohistochemistry studies in wild type and pendrin-deficient mice. The Specific Aims of the project are: 1. To determine the transport characteristics of pendrin in native renal tissue, 2. To determine if pendrin is upregulated in kidney during metabolic alkalosis, 3. To determine the renal phenotype of pendrin and 4. To determine the localization of pendrin in kidney. These studies will contribute to our understanding of how the mammalian kidney excretes an alkaline load.

哺乳动物的肾脏具有大量排泄碱负荷的能力。例如，尽管巨大的基本负荷，但在饮用水中给予等渗Nahco3的啮齿动物只会形成一种温和的代谢碱。肾脏排泄大碱负荷的能力部分是通过在B插入细胞中的顶端阴离子交换介导的皮质收集管（CCD）中的活性HCO3-分泌。虽然顶端阴离子交换在CCD中的功能上是表征的，但介导该传输过程的基因产物仍然存在争议。然而，我们的实验室和合作者的工作表明，一种阴离子交换器Pendrin位于大鼠，人和小鼠中非A互嵌小细胞的顶膜上。此外，我们的实验室证明，彭德林介导小鼠CCD中HCO3-的分泌。该转运蛋白是否代表推定的顶端阴离子交换器仍有待完全测试。敲除小鼠的发展极大地促进了体内彭德林肾脏生理的研究。由于没有特定的pendrin或顶端阴离子交换的抑制剂，因此可以将基因敲除小鼠用作生物抑制剂，并用于测试体外肾脏pendrin的转运特征。此外，使用这些动物的平衡研究将使我们能够确定这些缺陷的小鼠是否在碱负荷排泄中存在缺陷。因此，本提案将测试Pendrin是否代表CCD的推定阴离子交换器。此外，这些研究将有助于我们理解该转运蛋白的生理作用。为了回答我们的实验室和合作者的问题，将采用平衡研究，小管在体外灌注了体外，实时定量RT-PCR，免疫金细胞化学和免疫组织化学研究中，对野生型和Pendrin缺陷小鼠进行了研究。该项目的具体目的是：1。确定天然肾脏组织中的彭氏蛋白的转运特征，2。确定pendrin在代谢性碱中毒期间是否在肾脏中上调pendrin，3。确定Pendrin和4的肾脏表型和4。确定Pendrin在肾脏中的定位。这些研究将有助于我们理解哺乳动物肾脏如何排泄碱性负荷。