Molecular Basis of Potassium Channels in the Kidney

肾脏钾通道的分子基础

• 批准号: 8882403
• 负责人: Paul A Welling
• 金额: $ 33.39万
• 依托单位: UNIVERSITY OF MARYLAND BALTIMORE
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-01-01 至 2016-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8882403
• 关键词: Address; Amino Acids; Automobile Driving; Basolateral Sorting Signal; Binding; Binding Sites; Biochemical; Biological; C-terminal; Cell physiology; Cell surface; Cells; Cellular biology; Clathrin-Coated Vesicles; Complex; Data; Disease; Distal; Duct (organ) structure; Ensure; Equilibrium; Exhibits; Funding; Goals; Golgi Apparatus; Health; Homeostasis; Image; Investigation; Ion Channel; Kidney; Knockout Mice; Ligands; Location; Membrane; Membrane Protein Traffic; Membrane Proteins; Methods; Minerals; Molecular; Molecular Chaperones; Mutation; Nephrons; Physiological; Play; Potassium; Potassium Channel; Process; Protein Isoforms; Proteins; Publishing; Recruitment Activity; Role; Sesame - dietary; Signal Transduction; Site; Sodium Chloride; Sorting - Cell Movement; Structure; Surface; Syndrome; System; Techniques; Testing; Transcription Factor AP-1; Vesicle; Wild Type Mouse; base; basolateral membrane; density; design; gamma-Aminobutyric Acid; human PHEMX protein; in vivo; insight; novel; poly(L-glutamic acid(60)-L-alanine(30)-L-tyrosine(10)); programs; protein aminoacid sequence; scaffold; secretion process; trafficking

DESCRIPTION (provided by applicant): The overarching goal of the present proposal is to develop a mechanistic explanation of the poorly understood trafficking processes that drive basolateral membrane localization and physiologically regulate the cell surface density of two closely related channels (Kir2.3 and Kir4.1, mutations in which are associated with EAST/Sesame syndrome) in the distal nephron. The program logically builds on our recent discoveries, defining the trafficking signals in these channels and the elucidating the intracellulr sorting and retention machinery that interact with them. Specifically, we will address the following critical and timely questions: 1. How does the Golgi Export patch in Kir channels influence basolateral sorting? Unlike conventional trafficking signals, which are typically comprised of short linear peptide sequences, we discovered that residues embedded its tertiary structure dictate Golgi exit of a prototypical potassium Kir channel. This signal patch forms a recognition site for interaction with the AP1A adaptor complex, thereby marking channels for incorporation into clathrin-coated vesicles at the trans- Golgi. Here we test the hypothesis that the conserved patch signal found in Kir2.3 and Kir4.1 initiates polarized trafficking by selecting channels as cargo for inclusion into clathrin-coated vesicles. 2. How are the basolateral trafficking signals in the C- terminal region of Kir channels interpreted? Based on our published and preliminary observation, we propose that once channels are marked for inclusion into clathrin-coated vesicles, other signals direct basolateral delivery by interacting basolateral trafficking chaperone(s). 3. What is the basis for basolateral Kir channel remodeling in the renal cortical collecting duct during potassium adaptation? This aim is designed to test the hypothesis that a previously unrecognized Kir channel remodeling process, involving Kir2.3 and Kir4.1 and a basolateral PDZ retention complex, underpins the increase in the basolateral membrane conductance in potassium adaptation. By addressing these questions, the program of investigation will provide new insights into the fundamental trafficking mechanisms that control potassium secretion in health and to understand what happens when trafficking signals and trafficking machiery goes wrong in disease.

描述（由申请方提供）：本提案的总体目标是对驱动基底外侧膜定位和生理学调节远端肾单位中两个密切相关通道（Kir2.3和Kir4.1，其中突变与EAST/芝麻综合征相关）的细胞表面密度的运输过程进行机制解释。该计划在逻辑上建立在我们最近的发现，定义这些渠道中的贩运信号，并阐明与它们相互作用的细胞内分选和保留机制。具体而言，我们将解决以下关键和及时的问题：1。Kir通道中的高尔基体出口斑块如何影响基底外侧分选？与通常由短线性肽序列组成的常规贩运信号不同，我们发现嵌入其三级结构的残基决定高尔基体退出原型钾Kir通道。该信号斑形成了与AP 1A衔接子复合物相互作用的识别位点，从而标记了在反式高尔基体处掺入网格蛋白包被的囊泡的通道。在这里，我们测试的假设，在Kir2.3和Kir4.1中发现的保守的补丁信号启动极化贩运选择通道作为货物纳入网格蛋白包被的囊泡。2. Kir通道C末端区域的基底外侧运输信号是如何解释的？基于我们发表的和初步的观察，我们提出，一旦通道被标记为包含在网格蛋白包被的囊泡中，其他信号通过相互作用的基底外侧贩运分子伴侣指导基底外侧递送。3.钾适应过程中肾皮质集合管基底外侧Kir通道重构的基础是什么？这一目的旨在验证一个假设，即以前未被认识到的Kir通道重塑过程，涉及Kir2.3和Kir4.1和基底外侧PDZ保留复合物，支持钾适应中基底外侧膜电导的增加。通过解决这些问题，调查计划将为控制健康钾分泌的基本贩运机制提供新的见解，并了解当贩运信号和贩运机制在疾病中出错时会发生什么。