Role of Poldip2 in endothelial barrier function and inflammation in the lung

项目摘要 内皮细胞排列在所有血管的管腔中，并在维持屏障功能中起关键作用 血管系统。屏障功能减弱，血管通透性随之增加， 血浆蛋白和白细胞已经被描述为在病理状况中 窘迫综合征和急性肺损伤。由此产生的组织水肿与通气的丧失有关。 肺组织和高死亡率和发病率。我们发现聚合酶δ相互作用蛋白- Poldip 2是一种具有多个结合伴侣的蛋白质，是肺内皮屏障的重要调节剂 功能值得注意的是，使用脂多糖（LPS）诱导的肺损伤模型，我们观察到， Poldip 2杂合缺失几乎消除了LPS诱导的屏障功能障碍和 白细胞进入肺部，显著提高生存率。Poldip 2耗尽对渗透率的影响是 在具有Poldip 2的内皮特异性缺失的小鼠中表型复制。这些动物的表型是 令人震惊的是，这表明我们已经确定了一个新的和以前不受重视的疾病的主要目标， 与EC屏障功能障碍有关。在这个项目中，我们将探索分子和细胞机制， 负责这种令人印象深刻的保护，以深入了解潜在的新疗法。第一个目标，我们 将研究内皮Poldip 2在体内和体外屏障功能和炎症中的特定作用， 使用LPS诱导的损伤模型。目的2旨在确定内皮细胞 Poldip 2调节屏障功能和炎症，重点关注VE-钙粘蛋白信号转导及其 与血管生成素2以及Poldip 2相互作用的伴侣Nox 4相互作用。最后，在目标3中，我们计划 确定Poldip 2功能如何在分子和细胞水平上调节。在一起，这三个 aims将使我们对预防富含蛋白质的水肿的新治疗靶点有新的认识 和肺损伤后白细胞外渗，并将描绘潜在的分子机制。 我们的工作将提供对调节渗透性和炎症的基本机制的深入了解， 对其他炎症性疾病具有潜在的广泛适用性。

PROJECT SUMMARY Endothelial cells line the lumen of all blood vessels and play a critical role in maintaining the barrier function of the vasculature. Diminished barrier function and the consequent increase in vascular permeability to plasma proteins and leukocytes has been described in pathological conditions such as acute respiratory distress syndrome and acute lung injury. The resulting tissue edema is associated with loss of aerated lung tissue and high mortality and morbidity. We have discovered that Polymerase delta interacting protein- 2 (Poldip2), a protein with multiple binding partners, is an important modulator of lung endothelial barrier function. Remarkably, using a lipopolysaccharide (LPS)-induced lung injury model, we observed that heterozygous deletion of Poldip2 nearly abolishes LPS-induced barrier dysfunction and extravasation of leukocytes into the lung, markedly improving survival. The effect of Poldip2 depletion on permeability is phenocopied in mice with endothelial-specific deletion of Poldip2. The phenotype of these animals is striking, suggesting that we have identified a novel and previously unappreciated major target for diseases related to EC barrier dysfunction. In this project, we will probe the molecular and cellular mechanisms responsible for this impressive protection to gain insight into potential new therapies. In the first aim, we will examine the specific role of endothelial Poldip2 in barrier function and inflammation in vivo and in vitro, using the LPS-induced injury model. Aim 2 is designed to define the mechanisms by which endothelial Poldip2 regulates barrier function and inflammation, focusing on the role of VE-cadherin signaling and its interplay with angiopoietin-2, as well as the Poldip2-interacting partner Nox4. Finally, in Aim 3, we plan to determine how Poldip2 function is regulated at the molecular and cellular levels. Together, these three aims will allow us to gain new insight into a novel therapeutic target for prevention of protein-rich edema and leukocyte extravasation following lung injury and will delineate the underlying molecular mechanisms. Our work will provide insight into a fundamental mechanism regulating permeability and inflammation that has potential broad applicability to other inflammatory diseases.