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ATP1A1-dependent Regulation of Sodium Handling by the Renal Proximal Tubule: Mechanism and Implications in Salt-Sensitivity

肾近端小管钠处理的 ATP1A1 依赖性调节：盐敏感性的机制和影响

基本信息

批准号：
10474518
负责人：
Sandrine V Pierre
金额：
$ 34.18万
依托单位：
MARSHALL UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2021
资助国家：
美国
起止时间：
2021-08-24 至 2025-06-30
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/10474518
关键词：
ATP phosphohydrolase ATP1A1 gene Abbreviations Apical Attention Bicarbonates Binding Binding Sites Biochemical Blood Pressure Monitors Cardiac Glycosides Cardiac Myocytes Cardiovascular system Cell Culture Techniques Cell Line Cells Chronic Clinical Communities Complex Cytoskeleton Development Disease Epidermal Growth Factor Receptor Epithelial Cells Failure Fluid Balance Foundations Generations Genetic Glomerular Filtration Rate Homeostasis Hypertension Investigation Ion Pumps Ion Transport Kidney Knock-out Laboratories Ligands Lipids Mediating Membrane Proteins Modeling Molecular Molecular Conformation Mus Muscle Contraction Mutation Na(+)-K(+)-Exchanging ATPase Natriuresis Organ Ouabain Patients Peptides Pharmacology Phenotype Phosphotransferases Physiological Physiology Protein Isoforms Proteins Protocols documentation Proximal Kidney Tubules Reactive Oxygen Species Receptor Signaling Regulation Reporting Role Scaffolding Protein Second Messenger Systems Signal Transduction Signaling Protein Sodium Sodium Chloride Telemetry Testing Textbooks Therapeutic Transactivation Work animal tissue blood pressure control chloride-cotransporter potassium electrical potential epithelial Na+ channel hypertensive in vivo knock-down mouse model mutant neurotransmission receptor receptor function renal epithelium salt balance salt intake saluretic sodium-phosphate cotransporter proteins src-Family Kinases symporter tool uptake virtual

项目摘要

ATP1A1 is the only Na/K-ATPase (NKA) isoform expressed in the kidney. As stated in physiology textbooks, NKA is the enzymatic machinery that powers energy storage in the form of a transmembrane Na+ gradient, which is essential for renal salt handling and the control of blood pressure. In the renal proximal tubule (RPT), activation of NKA-mediated classic ion transport function decreases natriuresis through activation of both basolateral (NKA) and apical (NHE3) Na+ reabsorption. In contrast, activation of the more recently discovered NKA signaling function triggers a cellular redistribution of both NKA and NHE3 in RPT cells, which decreases Na+ uptake. Hence, RPT NKA simultaneously serves two opposing roles in Na+ handling: anti-natriuretic through its classic ATPase-driven ion transport function, and natriuretic through its more recently recognized receptor/signaling function. To date, the relative contributions of these two NKA functions to the net RPT Na+ handling in vivo is a fundamentally and therapeutically essential question that has been virtually impossible to answer. NKA signaling, which is both distinct and independent from NKA classic enzymatic ion-transporting function, was first brought to the attention of the scientific community by the work of Dr. Zijian Xie in ouabain-treated cardiac myocytes and renal epithelial cells. Mechanistically, binding of NKA specific ligands such as the cardiotonic steroid (CTS) ouabain activates Src, resulting in the activation of multiple protein/lipid kinases and the generation of intracellular second messengers. Numerous groups around the world have expanded the concept of non- enzymatic signaling function of NKA, while we have focused on the mechanism by which NKA is engaged in direct interaction with several signaling and scaffolding proteins including Src. This has allowed us to develop ATP1A1 mutants with intact enzymatic function but defective ability of interaction with signaling partners. Critically, we have developed a hypomorphic mouse (RPTα1-/-) with a RPT-specific reduction of 70% of NKA α1. The hyper-reabsorptive renal phenotype of this mouse suggests that NKA signaling is not only physiologically relevant, but also functionally prevalent in the regulation of RPT Na+ handling. We have established feasibility of RPT-specific rescue of the hypomorphic RPTα1-/- mouse with either wild-type or Src-binding null mutant forms of NKA, and propose to use those new tools to test the central hypothesis that NKA α1 (ATP1A1) exerts a tonic inhibition of apical NHE3 and basolateral Na+ transporters in the RPT. We further surmise that this regulatory mechanism has a prevalent regulatory role in RPT Na+ handling (Aim 1), depends on NKA α1/Src interaction (Aim 2), and enables NKA α1 ligands such as CTS to modulate RPT Na+ reabsorption (Aim 3). Successful completion of the proposed investigation shall reveal a hitherto unrecognized regulatory mechanism of salt handling by RPT NKA α1, the molecular basis of this regulation, an integrated compensatory transport network, and their impact on renal physiology and the development of salt sensitivity.

ATP1A1 是肾脏中表达的唯一 Na/K-ATP 酶 (NKA) 亚型。正如生理学教科书中所说， NKA 是一种酶机制，以跨膜 Na+ 梯度的形式为能量储存提供动力，对于肾盐处理和血压控制至关重要。在肾近曲小管 (RPT) 中，激活 NKA 介导的经典离子转运功能通过激活两侧基底外侧 (NKA) 来降低尿钠排泄和顶端 (NHE3) Na+ 重吸收。相反，最近发现的 NKA 信号传导的激活该功能触发 RPT 细胞中 NKA 和 NHE3 的细胞重新分布，从而减少 Na+ 的吸收。因此，RPT NKA 在 Na+ 处理中同时发挥两个相反的作用：通过其经典的抗钠尿作用 ATP 酶驱动的离子转运功能，以及通过其最近识别的受体/信号传导实现利尿钠排泄功能。迄今为止，这两种 NKA 功能对体内净 RPT Na+ 处理的相对贡献是从根本上和治疗上来说至关重要的问题实际上是不可能回答的。 NKA 信号传导，它与NKA经典的酶促离子传输功能不同且独立，首次被引入谢子建博士在哇巴因处理的心肌细胞中的工作引起了科学界的关注肾上皮细胞。从机制上讲，NKA 特异性配体的结合，例如强心类固醇 (CTS) 哇巴因激活 Src，导致多种蛋白/脂质激酶的激活并产生细胞内第二信使。世界各地的许多团体都扩展了非非的概念。 NKA 的酶信号传导功能，而我们重点关注 NKA 参与的机制与包括 Src 在内的多种信号传导和支架蛋白直接相互作用。这使我们能够发展 ATP1A1 突变体具有完整的酶功能，但与信号传导伙伴相互作用的能力有缺陷。至关重要的是，我们开发了一种亚效型小鼠（RPTα1-/-），其 RPT 特异性减少了 70% 的 NKA α1。该小鼠的高重吸收肾表型表明 NKA 信号传导不仅在生理学上相关，而且在 RPT Na+ 处理的调节中也具有功能上的普遍性。我们已经确定了可行性对具有野生型或 Src 结合无效突变体形式的低等态 RPTα1-/- 小鼠进行 RPT 特异性拯救 NKA 的研究，并建议使用这些新工具来检验 NKA α1 (ATP1A1) 发挥补品作用的中心假设抑制 RPT 中的顶端 NHE3 和基底外侧 Na+ 转运蛋白。我们进一步推测，这一监管机制在 RPT Na+ 处理中具有普遍的调节作用（目标 1），取决于 NKA α1/Src 相互作用（目标 2），并使 NKA α1 配体（例如 CTS）能够调节 RPT Na+ 重吸收（目标 3）。拟议调查的成功完成将揭示迄今为止未被认可的监管机制 RPT NKA α1 的盐处理，这种调节的分子基础，一种综合补偿运输网络，及其对肾脏生理和盐敏感性发展的影响。