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剂（CFTR）是一种多功能蛋白，可在上皮细胞的顶端质膜上运输氯化物。 CFTR还调节其他蛋白质的离子转运，例如上皮钠通道ENAC。 CFTR在气道上皮中通过ENAC抑制钠转运，而囊性纤维化（CF）的主要特征之一是ENAC在气道上皮中的多动症。但是，CFTR和ENAC发生调节性相互作用的机制尚不清楚。突变CFTR功能的药理学修复的努力集中在评估CFTR的氯化物转运特性的恢复上，并在很大程度上忽略了CFTR的其他功能，例如其与ENAC的相互作用。因此，这仍然是一个开放的问题，即突变CFTR功能的药理学修复是否还将恢复CFTR和ENAC的关键调节相互作用。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功能的药理策略的关键。其他人则建议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贩运有关的调节相互作用。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的改变。修复突变体CFTR的药理学剂可能会调节这些贩运相互作用。一些这样的药物可能会通过改变胞质分子伴侣的表达来影响运输。由于CFTR和ENAC的某些胞质结构域对于调节性相互作用似乎至关重要，因此伴侣与这些胞质域的结合可能调节这种相互作用。本提案将基于这些研究和初步数据，并通过针对以下特定目的的研究解决了这一假设：1）确定CFTR和ENAC通过这些动力学机制调节上皮细胞中对方的细胞内运输。 2）确定胞质70千达尔顿分子伴侣伴侣影响并调节上皮细胞中CFTR和ENAC的这些运输相互作用的机制。相关性：肺部和气道捍卫环境免受环境的主要机制取决于呼吸性上皮中的适当离子运输。这种离子转运在囊性纤维化中异常，并导致明显的发病率和死亡率。这些数据将更好地了解不仅囊性纤维化肺部疾病的发病机理，还可以更好地理解气道的其他许多疾病，以及其他分泌性上皮的疾病。