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Coordinated SLC12A3/SLC12A6/SL26A4 electroneutral transport pathways maintain K+ homeostasis and acid-base balance

协调的 SLC12A3/SLC12A6/SL26A4 电中性转运途径维持 K 稳态和酸碱平衡

基本信息

批准号：
10735503
负责人：
Eric J Delpire
金额：
$ 78.36万
依托单位：
VANDERBILT UNIVERSITY MEDICAL CENTER
依托单位国家：
美国
项目类别：
财政年份：
2017
资助国家：
美国
起止时间：
2017-06-15 至 2027-05-31
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/10735503
关键词：
Ablation Acid-Base Equilibrium Alkalosis Animals Anions Apical Bicarbonates Cell membrane Cell model Cellular biology Chlorides Consumption Coupling Data Diet Dietary Potassium Distal Distal convoluted renal tubule structure Ensure Equilibrium Excretory function Food Genes Genetic Transcription Genetically Engineered Mouse Gitelman syndrome Homeostasis In Vitro Intake Intercalated Cell Investigation Kidney Knockout Mice Knowledge Link Mediating Metabolic Modeling Molecular Mus Nephrons Pathway interactions Persons Phenotype Phosphorylation Physiological Physiology Potassium Proteins Public Health Publishing Regulation Role SLC12A3 gene Sodium Sodium Chloride Syndrome Testing Textbooks Therapeutic Intervention Translations Variant Vegetarian diet Wild Type Mouse absorption apical membrane chloride-cotransporter potassium clinical care dietary in vitro Model in vivo inhibitor innovation interdisciplinary approach knockout animal mouse model multidisciplinary novel novel therapeutics potassium bicarbonate preservation prevent programs response symporter targeted treatment thiazide urinary wasting

项目摘要

Alkaline diets and alkalemia have a profound impact on potassium homeostasis, but the underlying mechanisms remain poorly understood. Here we propose an innovative plan to close this significant knowledge gap, building on our recent discovery of a long sought-after electroneutral potassium transport pathway. Our data reveal that dietary alkaline loading stimulates the expression of the electroneutral KCl cotransporter, KCC3a (Slc12a6), in parallel with the Cl-/HCO3- exchanger, pendrin (Slc26a4), on the B- type intercalated cell apical membrane and the activation of the thiazide-sensitive sodium-chloride, NCC (Slc12a3), in the Distal Convoluted Tubule. Here we advance the overarching hypothesis that KCC3a is the long sought-after electroneutral potassium secretory pathway and propose the novel idea that coupling between KCC3a, pendrin, and NCC maintains potassium and acid-base balance in response to the consumption of alkaline and potassium-rich foods but drives potassium wasting in alkalosis. This new model will be rigorously tested by a multidisciplinary team of experts, combining state-of-the-art cellular biology and physiological phenotyping in novel genetically engineered mouse models. Aim 1 will test the hypothesis that KCC3a is activated in response to the consumption of alkaline diets and alkalosis to drive urinary potassium excretion. Intercalated-cell-specific KCC3 knockout mice will be investigated to a) test the contribution of KCC3 to potassium balance and b) to pendrin-mediated HCO3- secretion; c) elucidate the molecular mechanisms that underlie the regulation of KCC3 expression; c) test if KCC-specific inhibitors prevent the loss of K+ in alkalemia. Aim 2 will test the hypothesis that pendrin is co-activated with KCC3a to increase KHCO3 secretion. Pendrin knockout mice will be studied to determine: a) the contribution of pendrin to the regulation of KCC3a; and b) the physiologic consequences of uncoupling the transporters. We will also explore if KCC3a regulates pendrin through changes in pendrin transcription that involve changes in intracellular chloride. Aim 3 will test the hypothesis that alkalosis drives WNK-SPAK mediated phospho-activation of NCC to ensure electroneutral potassium bicarbonate secretion prevails over electrogenic potassium secretion. Newly developed DCT-specific loss and gain of SPAK mice and in vitro cell models will be examined to rigorously test this idea and explore the mechanism. In summary, this program of investigation should illuminate a new mechanism to explain how K+ and acid-base balance are preserved with the consumption of alkaline and potassium-rich foods, typical of the paleolithic and vegetarian diets. The investigation is also expected to change the textbook explanation of urinary potassium wasting in alkalosis, opening a new therapeutic horizon.

碱性饮食和碱血症对钾的体内平衡有着深远的影响，机制仍然知之甚少。在这里，我们提出了一个创新的计划，以关闭这一重大知识差距，建立在我们最近发现的一个长期追求的电中性钾转运通路我们的数据表明，膳食碱性负荷刺激表达的电中性氯化钾协同转运蛋白KCC 3a（Slc 12 a6），与Cl-/HCO 3-交换剂pendrin（Slc 26 a4）平行，位于B- 型插入细胞顶端膜和噻嗪敏感的氯化钠，NCC的激活（Slc 12 a3），在远端曲小管中。在这里，我们提出了一个总体假设，即KCC 3a是长期以来备受关注的电中性钾分泌途径，并提出了新的观点， KCC 3a，pendrin和NCC之间的平衡维持钾和酸碱平衡，以响应碱性和富含钾的食物的消耗，但驱动钾浪费在糖尿病。这个新该模型将由多学科专家团队进行严格测试，结合最先进的细胞新的基因工程小鼠模型的生物学和生理表型。目标1将测试假设KCC 3a被激活，以响应碱性饮食的消耗和驾驶的疲劳尿钾排泄将对嵌入细胞特异性KCC 3敲除小鼠进行研究，以进行a）试验 KCC 3对钾平衡贡献和B）对pendrin介导的HCO 3-分泌的贡献; c）阐明 KCC 3表达调节的分子机制; c）测试是否具有KCC特异性抑制剂防止碱血症中K+的损失。目的2将检验pendrin与以下物质共激活的假设： KCC 3a增加KHCO 3分泌。将研究Pendrin敲除小鼠以确定： pendrin对KCC 3a调节的贡献;和B）解偶联KCC 3a的生理后果。运输机我们还将探索KCC 3a是否通过改变pendrin转录来调节pendrin，涉及细胞内氯的变化。目标3将检验脑卒中驱动WNK-SPAK的假设 NCC介导的磷酸化激活，以确保电中性碳酸氢钾分泌占优势过度分泌钾。新开发的SPAK小鼠的DCT特异性损失和获得，以及我们将研究体外细胞模型，以严格检验这一想法并探索其机制。总之，这一项研究计划应该阐明一种新的机制来解释K+和酸碱平衡是如何被改变的。通过食用碱性和富含钾的食物来保存，这是旧石器时代的典型特征，素食这项调查还有望改变教科书对尿的解释碱中毒中的钾浪费，开辟了新的治疗视野。