Molecular determinants of lung barrier function

描述（由申请人提供）：急性肺损伤的生存能力与维持肺泡液清除的能力相关。肺泡液平衡部分是通过上皮紧密连接维持的，上皮紧密连接为细胞间的自由扩散创造了渗透性屏障。claudin家族中的跨膜蛋白是紧密连接的主要功能成分。哺乳动物大约有24种claudin和肺泡上皮细胞通过多种claudin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claudin组装成紧密连接的过程。然而，人们对claudin运输和组装的机制知之甚少，尤其是肺泡上皮细胞。此外，还没有确定管理不同的claudin如何混合的规则。为了确定克劳丁转运的机制，我们将使用一系列细胞和分子方法：1)确定emp家族蛋白在调节克劳丁转运、组装和屏障功能中的作用，2)确定克劳丁寡聚化的细胞内位点，确定调节异质克劳丁相互作用的基序，3)确定决定细胞外头对头结合特异性的克劳丁基序。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，以帮助设计预防肺泡渗漏伴肺损伤的策略。

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.