Regulatory Interactions of CFTR and ENaC

CFTR 和 ENaC 的监管相互作用

• 批准号: 7364518
• 负责人: Ronald C Rubenstein
• 金额: $ 41.13万
• 依托单位: CHILDREN'S HOSP OF PHILADELPHIA
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-07-01 至 2011-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7364518
• 关键词: Address; Apical; Binding; Cell membrane; Chloride Ion; Chlorides; Cystic Fibrosis; Cystic Fibrosis Transmembrane Conductance Regulator; Data; Disease; Environment; Epithelial; Epithelial Cells; Epithelium; Hyperactive behavior; Investigation; Ion Transport; Kinetics; Lung; Molecular; Molecular Chaperones; Morbidity - disease rate; Pathogenesis; Probability; Property; Proteins; Pulmonary Cystic Fibrosis; Sodium; Sodium Channel; Structure of respiratory epithelium; Surface; Testing; abstracting; airway epithelium; base; epithelial Na+ channel; improved; mortality; mutant; protein transport; repaired; restoration; trafficking

DESCRIPTION (provided by applicant): The Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) is a multifunctional protein that transports chloride across the apical plasma membrane of epithelial cells. CFTR also regulates ion transport by other proteins, such as the Epithelial Sodium Channel, ENaC. CFTR inhibits sodium transport by ENaC in airway epithelia, and one of the cardinal features of Cystic Fibrosis (CF) is hyperactivity of ENaC in the airway epithelia. However, the mechanism by which regulatory interactions of CFTR and ENaC occurs is not clear. Efforts at pharmacologic repair of mutant CFTR function have concentrated on assessing restoration of a mutant CFTR's chloride transport properties and have largely ignored other functions of CFTR, such as its interregulation with ENaC. It thus remains an open question whether pharmacologic repair of mutant CFTR function will also restore the critical regulatory interactions of CFTR and ENaC. Understanding the molecular basis of these critical regulatory interactions is therefore key in the implementation of pharmacologic strategies to improve CFTR function. Others have suggested that CFTR inhibits ENaC activity by decreasing ENaC open probability (Po). In contrast, our preliminary data strongly suggests that CFTR and ENaC may also have regulatory interactions related to intracellular trafficking. We will therefore test the hypothesis that: Regulatory interactions of CFTR and ENaC result in altered intracellular trafficking and surface expression of these channels in epithelial cells. Pharmacologic agents that repair mutant CFTR may modulate these trafficking interactions. Some such agents may influence trafficking by altering the expression of cytosolic molecular chaperones. As certain cytosolic domains of CFTR and ENaC appear critical for regulatory interactions, binding of chaperones to these cytosolic domains may regulate such interactions. The present proposal will build on these investigations and preliminary data and address this hypothesis with studies directed at the following Specific Aims: 1) To determine the kinetic mechanism by which CFTR and ENaC regulate each other's intracellular trafficking in epithelial cells. 2) To determine the mechanism by which cytosolic 70 kilodalton molecular chaperones influence and regulate these trafficking interactions of CFTR and ENaC in epithelial cells. Relevance: The major mechanism by which the lung and airway defends itself from the environment depends on proper ion transport in the respiratory epithelia. Such ion transport is aberrant in Cystic Fibrosis and leads to significant morbidity and mortality. These data will promote better understanding of the pathogenesis of not only Cystic Fibrosis lung disease, but also a number of other diseases of the airway, as well as diseases of other secretory epithelia.

描述（由申请人提供）：囊性纤维化跨膜电导调节器（CFTR）是一种多功能蛋白质，可将氯转运穿过上皮细胞的顶端质膜。 CFTR 还调节其他蛋白质的离子转运，例如上皮钠通道 (ENaC)。 CFTR 抑制气道上皮细胞中 ENaC 的钠转运，囊性纤维化 (CF) 的主要特征之一是气道上皮细胞中 ENaC 的过度活跃。然而，CFTR 和 ENaC 发生调控相互作用的机制尚不清楚。突变体 CFTR 功能的药理修复工作集中于评估突变体 CFTR 氯离子转运特性的恢复，而很大程度上忽略了 CFTR 的其他功能，例如其与 ENaC 的相互调节。因此，突变 CFTR 功能的药理修复是否也会恢复 CFTR 和 ENaC 的关键调节相互作用仍然是一个悬而未决的问题。因此，了解这些关键调控相互作用的分子基础是实施改善 CFTR 功能的药理学策略的关键。其他人认为 CFTR 通过降低 ENaC 开放概率 (Po) 来抑制 ENaC 活性。相比之下，我们的初步数据强烈表明 CFTR 和 ENaC 也可能具有与细胞内运输相关的监管相互作用。因此，我们将检验以下假设： CFTR 和 ENaC 的调节相互作用会导致上皮细胞中这些通道的细胞内运输和表面表达发生改变。修复突变 CFTR 的药物可能会调节这些运输相互作用。一些此类试剂可能通过改变胞质分子伴侣的表达来影响运输。由于 CFTR 和 ENaC 的某些胞质结构域似乎对于调节相互作用至关重要，因此分子伴侣与这些胞质结构域的结合可能会调节这种相互作用。目前的提案将建立在这些调查和初步数据的基础上，并通过针对以下具体目标的研究来解决这一假设：1）确定CFTR和ENaC相互调节上皮细胞内细胞内运输的动力学机制。 2) 确定胞质 70 kilodalton 分子伴侣影响和调节上皮细胞中 CFTR 和 ENaC 的运输相互作用的机制。相关性：肺和气道保护自身免受环境影响的主要机制取决于呼吸道上皮细胞中适当的离子运输。这种离子传输在囊性纤维化中是异常的，并导致显着的发病率和死亡率。这些数据将促进更好地了解囊性纤维化肺病的发病机制，还有许多其他气道疾病以及其他分泌上皮疾病的发病机制。