Molecular determinants of lung barrier function

描述(由申请人提供)：急性肺损伤的存活能力与维持肺泡液体清除的能力相关。肺泡液平衡在一定程度上是通过上皮的紧密连接来维持的，这种紧密连接为细胞间的自由扩散创造了一道渗透性屏障。Claudin家族的跨膜蛋白是紧密连接的主要功能成分。大约有24种哺乳动物克拉丁和肺泡上皮细胞利用多个克拉丁的差异表达来调节紧密连接屏障。最近的研究表明，肺泡上皮细胞也调节克拉丁组装成紧密连接的过程。然而，对于一般情况下，尤其是肺泡上皮细胞对claudin运输和组装的调控机制，人们知之甚少。此外，关于不同的克劳迪斯如何混合的规则还没有确定。为了确定Claudin运输的机制，我们将使用一系列的细胞和分子方法来：1)确定EMP家族蛋白在调节Claudin运输、组装和屏障功能中的作用，2)定义Claudin寡聚的细胞内位置并确定调控异构体Claudin相互作用的基序，3)确定决定细胞外头对头结合特异性的Claudin基序。通过确定对调节肺泡屏障功能至关重要的控制点，这些研究有望提供分子和细胞生物学基础，帮助设计预防肺损伤所致肺泡渗漏的策略。

DESCRIPTION (provided by applicant): The ability to survive acute lung injury correlates with the ability to maintain alveolar fluid clearance. Alveolar fluid balance is maintained, in part, by epithelial tight junctions which create a permeability barrier to free diffusion between cells. Transmembrane proteins in the claudin family are a major functional component of tight junctions. There are roughly two dozen mammalian claudins and alveolar epithelial cells use differential expression of multiple claudins to regulate the tight junction barrier. Recent work suggests that alveolar epithelial cells also regulate the process of claudin assembly into tight junctions. However, little is known about the mechanisms that regulate claudin trafficking and assembly in general and by alveolar epithelial cells in particular. Also, the rules governing how different claudins can intermix have not been identified. To define the mechanisms which underlie claudin trafficking, we will use a series of cell and molecular approaches to: 1) define roles for EMP-family proteins in regulating claudin traffic, assembly and barrier function, 2) define intracellular sites for claudin oligomerization and determine motifs regulating heteromeric claudin interactions and 3) identify claudin motifs which determine extracellular head-to-head binding specificity. By defining control points that are critical to regulate alveolar barrier function, these studies are expected to provide a molecular and cell biological basis to help design strategies to prevent the alveolar leak that accompanies lung injury.