Molecular Mechanism of ROMK Channel Function

ROMK通道功能的分子机制

基本信息

批准号：
7888961
负责人：
Paul A Welling
金额：
$ 37.5万
依托单位：
UNIVERSITY OF MARYLAND BALTIMORE
依托单位国家：
美国
项目类别：
财政年份：
1998
资助国家：
美国
起止时间：
1998-08-01 至 2015-05-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/7888961
关键词：
Adaptor Signaling Protein Address Aldosterone Apical Arts Automobile Driving Back Binding Sites Cell surface Cellular biology Clathrin Clathrin Adaptors Dietary Potassium Disease Distal Electrophysiology (science)Endocytosis Ensure Equilibrium Excretory function Exhibits Familial disease Goals Health Homeostasis Hypertension Imaging Techniques Intake KCNJ1 gene KCNJ1 protein Kidney Kidney Diseases Knockout Mice Life Location Lysosomes Membrane Protein Traffic Membrane Proteins Minerals Molecular Molecular Genetics Mutate Nephrons Pathway interactions Phosphorylation Phosphotransferases Physiological Physiology Play Potassium Potassium Channel Potassium Deficiency Principal Investigator Process Proteins Recycling Regulation Role Route Signal Pathway Signal Transduction Sodium Chloride Surface System TFAP2A gene Testing Ubiquitin Variant Work base coated pit density design hyperkalemia insight interdisciplinary approach member novel prevent public health relevance response scaffold secretion process trafficking ubiquitin ligase urinary

项目摘要

DESCRIPTION (provided by applicant): ROMK (Kir 1.1, product of he KCNJ1 gene) channels in the kidney are exquisitely regulated to adjust renal potassium excretion and maintain potassium balance. Clathrin-dependent endocytosis plays a critical role, limiting urinary potassium loss in potassium deficiency. In renal disease, aberrant ROMK endocytosis may contribute to potassium retention and life-threatening hyperkalemia. Available evidence indicates ROMK endocytosis is stimulated by WNKs, kinases that are mutated in a familiar disease of hyperkalemia and hypertension. This application builds on our discoveries that a novel variant of a "NPXY"-type signal in ROMK serves as a recognition site for binding to ARH, a member of a new class of clathrin-adaptor proteins, and this interaction marks channels for rapid endocytosis and eventual lysosomal degradation. Knockout mice, lacking ARH, exhibit an altered renal ROMK response to dietary potassium intake. To carry these breakthrough observations toward a completely new understanding of how potassium balance is achieved, we outline plans to: 1) conduct a complete system-to-molecule phenotypic characterization of the ARH knockout mouse to critically evaluate the physiological consequence of ARH-dependent ROMK endocytosis, 2) explore the involvement of a novel signaling pathway that physiologically regulates ARH, 3) elucidate the molecular mechanism by which WNK-1 stimulates ARH-dependent endocytosis and post-endocytic routing of ROMK to the lysosome. The studies should provide novel insights into the molecular basis of renal K handling and K homeostasis in health and disease while illuminating fundamental mechanisms of membrane protein targeting in the kidney. PUBLIC HEALTH RELEVANCE: ROMK potassium channels are tightly regulated in the kidney by membrane trafficking mechanisms, ensuring that potassium is precisely excreted in accord with the demands of potassium balance. Disruption of ROMK channel trafficking and surface expression can, in fact, have devastating consequences on salt and mineral balance. Despite its importance, a long-standing and fundamental question in cell biology and physiology has been how the number and location of these membrane proteins are precisely controlled. In the present proposal, we elucidate the molecular mechanisms driving membrane trafficking of these channels in health and study what may happen when these processes go awry in disease. Thus, the studies should provide novel insights into the molecular basis of renal K handling and K homeostasis in health and disease while illuminating fundamental mechanisms of membrane protein targeting in the kidney.

描述（申请人提供）：肾脏中的ROMK（Kir 1.1，KCNJ1基因的产物）通道受到精细调节，以调节肾脏钾排泄并维持钾平衡。网格蛋白依赖性内吞作用起着关键作用，可限制缺钾时尿钾的流失。在肾脏疾病中，异常的 ROMK 内吞作用可能导致钾潴留和危及生命的高钾血症。现有证据表明 ROMK 内吞作用受到 WNK 的刺激，WNK 是一种在常见的高钾血症和高血压疾病中发生突变的激酶。该应用建立在我们的发现之上，即 ROMK 中“NPXY”型信号的新变体可作为与 ARH（一类新型网格蛋白适配器蛋白的成员）结合的识别位点，并且这种相互作用标记了快速内吞作用的通道以及最终的溶酶体降解。缺乏 ARH 的基因敲除小鼠表现出对膳食钾摄入量的肾脏 ROMK 反应改变。为了将这些突破性的观察结果带入对如何实现钾平衡的全新理解，我们概述了以下计划：1) 对 ARH 敲除小鼠进行完整的系统到分子表型表征，以批判性地评估 ARH 依赖性 ROMK 的生理后果内吞作用，2) 探索生理调节 ARH 的新型信号通路的参与，3) 阐明 WNK-1 刺激 ARH 依赖性内吞作用的分子机制，以及ROMK 内吞后路由至溶酶体。这些研究应该为健康和疾病中肾脏钾处理和钾稳态的分子基础提供新的见解，同时阐明肾脏中膜蛋白靶向的基本机制。公共健康相关性：ROMK 钾通道在肾脏中受到膜运输机制的严格调节，确保钾根据钾平衡的要求精确排出。事实上，ROMK 通道运输和表面表达的破坏会对盐和矿物质平衡产生毁灭性后果。尽管其重要性，细胞生物学和生理学中长期存在的基本问题是如何精确控制这些膜蛋白的数量和位置。在本提案中，我们阐明了健康中驱动这些通道膜运输的分子机制，并研究了当这些过程在疾病中出错时可能会发生什么。因此，这些研究应该为健康和疾病中肾脏钾处理和钾稳态的分子基础提供新的见解，同时阐明肾脏中膜蛋白靶向的基本机制。