Apical CI/OH-/HCO3-exchanger in kidney and GI tract

肾脏和胃肠道的顶端 CI/OH-/HCO3-交换器

• 批准号: 6727910
• 负责人: MANOOCHER SOLEIMANI
• 金额: $ 36.58万
• 依托单位: UNIVERSITY OF CINCINNATI
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-01-06 至 2007-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6727910
• 关键词: antiport; apical membrane; bicarbonates; chloride ion; gastrointestinal system; genetically modified animals; immunocytochemistry; ion transport; kidney; laboratory mouse; membrane transport proteins; northern blottings; renal tubule; sodium chloride; western blottings

The apical chloride/base exchanger in kidney proximal tubule and gastrointestinal tract works in parallel with NHE3 and is essential for chloride absorption and fluid homeostasis. However, less is known about the molecular identity and the main functional mode of this exchanger. SLC26A6, also known as PAT1 or CFEX, is a member of a large, highly conserved family of ion transporters (designated as SLC26A) many of which mediate anion exchange. SLC26A6 can mediate CI'/HCO3-, Cl/formate and Cl-/oxalate exchanges, indicating that it is an ideal candidate for apical Cl/base exchange in proximal tubule. Our experiments demonstrate that SLC26A6 mediates CI-/HCO3- exchange, is located on the apical membrane of proximal tubule, small intestine and tubulovesicles of gastric parietal cells, and is upregulated by NH4+, a naturally occurring chemical in kidney proximal tubule and small intestine. We further demonstrate the presence of an apical CI/HCO3- exchange in rat and mouse isolated microperfused proximal tubules and in tubulovesicles of gastric parietal cells. We hypothesize that SLC26A6 is the main apical anion exchanger in kidney proximal tubule and duodenum, functions predominantly as a CI-/HCO3- exchanger under physiologic conditions and is responsible for the bulk of chloride absorption. In the stomach, PAT1 may be essential for neutralizing the luminal acidity of H-K-ATPase-containing vesicles during the resting state. The purpose of the current proposal is to ascertain the role of the apical CI-/IHCO3- exchanger and PAT1 (SLC26A6) in chloride (and fluid) absorption in kidney proximal tubule and gastrointestinal tract. Toward this end, we propose to: 1. Characterize the apical CI/HCO3- exchanger in isolated microperfused proximal tubule and ascertain its role in chloride reabsorption in the presence of solutions mimicking proximal tubule milieu, 2. Ascertain the role of SLC26A6 in apical Cltbase exchange and cr reabsorption in kidney proximal tubules using SLC26A6 (PAT1) null mice, 3. Examine the acute and chronic regulation of SLC26A6 (PAT1) and apical CI-/HCO3- exchanger in kidney proximal tubule, and 4. Determine the role of SLC26A6 in gastric and intestinal function, including CI absorption and protection against acid injury in the duodenum and acid secretion in the stomach, using SLC26A6 null mice. Insight into the functional and molecular properties of PAT1 and apical CI-/HCO3- exchange in kidney proximal tubule and upper gastrointestinal tract in physiologic states and examination of PAT1 deficient mice should significantly enhance our understanding regarding the apical CI-/base exchanger and cr absorption in epithelial tissues. They should further facilitate future investigations into the role of this transporter in pathophysiologic states affecting electrolyte and acid-base homeostasis.

肾脏近端小管和胃肠道中的顶氯化物/碱性交换器与NHE3并行起作用，对于氯化物的吸收和液体稳态至关重要。然而，对于该交换器的分子身份和主要功能模式，知之甚少。 SLC26A6，也称为PAT1或CFEX，是大型，高度保守的离子转运蛋白家族（称为SLC26A）的成员，其中许多介导了阴离子交换。 SLC26A6可以介导CI'/hco3-，Cl/fregate和Cl-/草酸盐交换，表明它是近端小管中顶端Cl/碱基交换的理想候选者。我们的实验表明，SLC26A6介导了CI-/HCO3-交换，位于胃壁细胞的近端小管，小肠和小管膜上，并由NH4+上调，一种自然 发生在肾脏近端小管和小肠中的化学物质。我们进一步证明了大鼠和小鼠分离的微孔近端小管和胃顶壁细胞的小管中存在顶端CI/HCO3-交换。我们假设SLC26A6是肾脏近端小管和十二指肠的主要根尖阴离子交换器，在生理条件下主要用作CII-/HCO3-交换器，并且负责大部分氯化物吸收。在胃中，PAT1对于中和含有H-K-ATPase囊泡的腔酸是必不可少的。电流的目的 提案是确定顶端CI-/IHCO3-交换器和PAT1（SLC26A6）在肾近端小管和胃肠道中的氯化物（和液体）吸收中的作用。为此，我们提出：1。在孤立的微孔近端小管中表征顶端CI/HCO3-交换器，并确定其在模拟溶液中的氯化物重吸收中的作用SLC26A6（PAT1）NULL小鼠，3。检查SLC26A6（PAT1）和顶端CI-/HCO3-口气中的急性和慢性调节在肾脏近端小管中，并确定SLC26A6在胃和肠功能，肠功能，肠功能，，确定SLC26A6的作用。 使用SLC26A6无效小鼠，包括十二指肠中的CI吸收和防御酸性损伤和胃中的酸性损伤。洞悉生理状态中肾脏近端小管和上胃肠道的PAT1和顶端CI-/HCO3-交换的功能和分子特性，并检查PAT1缺乏小鼠应显着增强我们对上皮组织中基础CII/碱基交换器的理解。他们应进一步促进对这种转运蛋白在影响电解质和酸碱稳态的病理生理状态中的作用的未来研究。