Epithelial Na Channels: Structure-Function Studies

上皮 Na 通道：结构功能研究

• 批准号: 7367050
• 负责人: Thomas R Kleyman
• 金额: $ 29.97万
• 依托单位: UNIVERSITY OF PITTSBURGH AT PITTSBURGH
• 依托单位国家: 美国
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-08-01 至 2010-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7367050
• 关键词: Accounting; Address; Affect; Amiloride; Amino Acids; Blood Pressure; C-terminal; Cations; Cues; Cysteine; Data; Duct (organ) structure; Engineering; Epithelial; Epithelial Cells; Epithelium; Extracellular Domain; Extracellular Fluid; Figs - dietary; Genetic Polymorphism; Human; Kidney; Kinetics; Mediating; Membrane; Mucociliary Clearance; Mutation; Na(+)-K(+)-Exchanging ATPase; Oocytes; Regulation; Research; Resistance; Role; Side; Site; Site-Directed Mutagenesis; Sodium; Sodium Channel; Structure; Structure-Activity Relationship; Surface; airway epithelium; airway surface liquid; apical membrane; base; blood pressure regulation; cadmium ion; epithelial Na+ channel; extracellular; research study; response; stoichiometry; trafficking; urinary

DESCRIPTION (provided by applicant): Epithelial sodium channels (ENaCs) mediate reabsorptive sodium transport across epithelial cell layers in conjunction with a basolateral Na+/K+-ATPase. These channels have a key role in the regulation of urinary Na+ reabsorption, extracellular fluid volume homeostasis and blood pressure. ENaC-dependent Na+ reabsorption across airway epithelia has a significant role in regulating the volume of airway surface liquids and mucociliary clearance. Important functional domains have been identified, including sites that affect channel gating, trafficking and cation selectivity. Studies proposed in this application will address questions regarding ENaC structure-function relationships. We recently identified sites within alpha- and gammasubunit extracellular domains where mutations affect channel gating kinetics and alter channel regulation by external Ni2+, Zn2+ and Na+ (Na+ self-inhibition). Experiments proposed in Aim 1 will use site-directed mutagenesis to explore the role of residues within these extracellular sites and the role of highly conserved cysteine residues in modulating channel activity in response to extracellular factors. Experiments proposed in Aim 2 will examine the structural organization of the channel's selectivity filter. Experiments proposed in Aim 3 will characterize a region within the carboxyl-terminus of the alpha subunit that is distinct from the PY motif and regulates ENaC trafficking. Successful completion of the studies proposed in this application will provide a more detailed understanding of key structural features of epithelial sodium channels.

描述(由申请人提供)：上皮钠通道(ENaCs)与基底侧方的Na+/K+-ATPase一起，通过上皮细胞层介导重吸收钠的转运。这些通道在尿钠重吸收、细胞外液容量动态平衡和血压的调节中起着关键作用。通过呼吸道上皮细胞的ENAC依赖的Na+重吸收在调节呼吸道表面液体的量和粘液纤毛清除方面具有重要的作用。已经确定了重要的功能结构域，包括影响通道门控、运输和阳离子选择性的位点。本申请中提出的研究将解决有关ENaC结构-功能关系的问题。我们最近在α和γ亚基胞外区中发现了突变影响通道门控动力学的位置，并改变了外部Ni2+、Zn2+和Na+对通道的调节(Na+自抑制)。目标1中提出的实验将使用定点突变来探索这些胞外位点内残基的作用，以及高度保守的半胱氨酸残基在调节细胞外因子反应的通道活性中的作用。目标2中提出的实验将检查通道选择性过滤器的结构组织。目标3中提出的实验将表征阿尔法亚单位羧基末端的一个区域，该区域与PY基序不同，并调节ENaC的运输。本申请中建议的研究的成功完成将提供对上皮性钠通道关键结构特征的更详细的了解。