Ion channel-transporter interactions

离子通道-转运体相互作用

• 批准号: 9206169
• 负责人: Geoffrey W Abbott
• 金额: $ 28.21万
• 依托单位: UNIVERSITY OF CALIFORNIA-IRVINE
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-04-01 至 2019-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9206169
• 关键词: Address; Atrial Fibrillation; Basic Science; Biochemical; Biological Assay; Biosensor; Breathing; Calmodulin; Cells; Cellular biology; Cerebrospinal Fluid; Chimera organism; Chinese Hamster Ovary Cell; Choroid Plexus Epithelium; Co-Immunoprecipitations; Complement; Complex; Coupled; Data; Diabetes Mellitus; Disease; Electrophysiology (science); Employee Strikes; Epithelial; Epithelial Cells; Exhibits; Family; Fluorescent Antibody Technique; Future; Gated Ion Channel; Glucose Transporter; Glucosides; Health; Heart; Human; In Vitro; Influentials; Inositol; Ion Channel; Ion Channel Gating; Ions; Knock-in Mouse; Knockout Mice; Life; Link; Long QT Syndrome; Mass Spectrum Analysis; Membrane; Membrane Lipids; Molecular; Molecular Conformation; Movement; Mus; Mutagenesis; Mutation; Nutrient; Osmolar Concentration; Pathogenesis; Pharmacology; Phosphatidylinositol 4,5-Diphosphate; Phosphoric Monoester Hydrolases; Physiological; Physiology; Positron-Emission Tomography; Potassium; Potassium Channel; Process; Production; Property; Protein Biochemistry; Protein Isoforms; Proteins; Regulation; Role; Signal Transduction; Signaling Molecule; Site; Site-Directed Mutagenesis; Sodium; Sphingomyelinase; Stereoisomer; Structure of choroid plexus; Testing; Thyroid Gland; Tissues; Xenopus oocyte; behavior test; extracellular; flexibility; in vitro Assay; in vivo; knockout gene; member; mutant; nervous system disorder; novel; precursor cell; public health relevance; response; scyllo-inositol; sensor; solute; sugar; symporter; uptake; voltage

 DESCRIPTION (provided by applicant): The KCNQ1 voltage-gated potassium (Kv) channel pore-forming (a) subunit is ubiquitously expressed and linked to life-threatening human disorders including Long QT syndrome, atrial fibrillation and diabetes. KCNQ1 exhibits a high degree of functional flexibility enabled by co-assembly with KCNE family β subunits, facilitating roles both in excitable cell repolarization, and as a constitutively active K+ channel in polarized epithelial cells. Na+-coupled solute transport is crucial for uptake of ions and solutes including sugars and myo-inositol, an important osmolyte and precursor for cell signaling molecules. We recently discovered that KCNQ1 forms complexes with several different Na+-coupled solute transporters, and that at least two of these novel complexes are required for normal epithelial cell activity - in the thyroid and choroid plexus. Using in vitro functional studies, we found that KCNQ1 and the Na+-dependent myo-inositol transporters SMIT1 and SMIT2 reciprocally regulate each other's function. We also recently identified several other channel-transporter interactions, including KCNQ4-SMIT1, KCNQ1-SGLT1 (Na+-coupled glucose transporter), and KCNQ1-NIS (Na+/I- symporter). Here, we will elucidate molecular mechanisms of function, interaction, and physiological relevance of this novel and potentially widespread class of macromolecular signaling complexes. Three main questions are addressed. First, which channel domains and functions regulate transporter activity? Using mutagenesis, pharmacological agents and functional analyses, we will test the hypothesis that the KCNQ1 pore and voltage sensor modules can independently influence activity of co-assembled solute transporters. We will also use protein biochemistry in conjunction with channel chimeras and mutagenesis to elucidate channel domains crucial for physical interaction with transporters, in vitro. Second, why are channel-transporter complexes required? Using electrophysiological and solute uptake assays in vitro we will test the hypothesis that KCNQ1 acts as a biosensor in complexes with SMIT1 and SMIT2, facilitating responses to changes in osmolarity, membrane lipid composition, pH and Ca2+. Third, where do channel-transporter complexes occur in vivo? Aided by several knockout mouse lines, we will locate channel-transporter complexes, and utilize positron emission tomography to specifically test for the requirement of KCNQ1-KCNE regulation of SGLT family transporters, in vivo. Na+-coupled solute transporters, and Kv channel a subunits including KCNQ1, exhibit broad distribution, wide tissue expression overlap, and high biomedical significance. Together with our recent findings, this suggests that potassium channel-transporter complexes have the potential to be highly influential in mammalian physiology and in the pathogenesis of a number of prevalent human disorders.

 描述（由申请人提供）：KCNQ1 电压门控钾 (Kv) 通道成孔 (a) 亚基普遍表达，并与危及生命的人类疾病相关，包括长 QT 综合征、心房颤动和糖尿病。通过与 KCNE 家族 β 亚基共组装实现功能灵活性，促进在可兴奋细胞复极化中的作用，并作为组成型活性偏振 K+ 通道 Na+ 偶联溶质转运对于离子和溶质（包括糖和肌醇）的摄取至关重要，肌醇是细胞信号分子的重要渗透剂和前体，我们最近发现 KCNQ1 与几种不同的 Na+ 偶联溶质转运蛋白形成复合物，并且通过体外功能研究，甲状腺和脉络丛的正常上皮细胞活性至少需要其中两种。我们发现 KCNQ1 和 Na+ 依赖性肌醇转运蛋白 SMIT1 和 SMIT2 相互调节彼此的功能，我们最近还发现了几种其他通道转运蛋白相互作用，包括 KCNQ4-SMIT1、KCNQ1-SGLT1（Na+ 偶联葡萄糖转运蛋白）和 KCNQ1-NIS。 （Na+/I- 同向转运蛋白）。在这里，我们将阐明功能、相互作用和生理学的分子机制。这种新型且可能广泛传播的大分子信号复合物的相关性首先是哪些通道域和功能调节转运蛋白活性？我们将使用诱变、药理学试剂和功能分析来检验 KCNQ1 孔和电压的假设。传感器模块可以影响共组装的溶质转运蛋白的活性，我们还将独立使用蛋白质生物化学与通道嵌合体和诱变来阐明对体外与转运蛋白的物理相互作用至关重要的通道域。其次，为什么需要通道转运蛋白复合物？使用体外电生理学和溶质摄取测定，我们将测试 KCNQ1 在与 SMIT1 和 SMIT2 复合物中充当生物传感器的假设，促进对渗透压、膜脂成分、pH 和 Ca2+ 变化的反应。第三，通道-转运蛋白复合物在体内发生在哪里？在几个敲除小鼠品系的帮助下，我们将定位通道-转运蛋白复合物，并利用正电子发射断层扫描专门测试体内 SGLT 家族转运蛋白和 Kv 通道 a 亚基 (包括 KCNQ1) 的 KCNQ1-KCNE 调节要求，与我们一起。最近的研究结果表明，钾通道-转运蛋白复合物有可能对哺乳动物生理学和许多流行的人类疾病的发病机制产生高度影响。