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（由申请方提供）：囊性纤维化跨膜传导调节因子（CFTR）是一种多功能蛋白质，可将氯离子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，如上皮钠通道（ENaC）。CFTR抑制气道上皮中ENaC的钠转运，并且囊性纤维化（CF）的主要特征之一是气道上皮中ENaC的过度活性。然而，CFTR和ENaC的调节相互作用发生的机制尚不清楚。在突变CFTR功能的药理学修复方面的努力集中在评估突变CFTR的氯离子转运特性的恢复上，并且在很大程度上忽略了CFTR的其他功能，例如其与ENaC的相互调节。因此，突变CFTR功能的药理学修复是否也将恢复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调节相互作用。因此，我们将测试的假设，即：调节CFTR和ENaC的相互作用，改变细胞内运输和表面表达这些通道在上皮细胞。修复突变CFTR的药物可能会调节这些运输相互作用。一些这样的代理人可能会影响运输通过改变细胞溶质分子伴侣的表达。由于CFTR和ENaC的某些胞质结构域对于调节相互作用似乎是关键的，所以伴侣与这些胞质结构域的结合可以调节这种相互作用。本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的的研究来解决这一假设：1）确定CFTR和ENaC在上皮细胞中相互调节细胞内运输的动力学机制。2)确定细胞溶质70千道尔顿分子伴侣影响和调节上皮细胞中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转运。这种离子转运在囊性纤维化中是异常的，并导致显著的发病率和死亡率。这些数据将促进更好地理解不仅囊性纤维化肺病的发病机制，而且还包括许多其他气道疾病以及其他分泌性上皮细胞疾病。