Regulation of Lung Epithelial Fibrinolysis by Urokinase

描述(申请人提供)：纤维蛋白代谢紊乱和血管外纤维蛋白沉积与肺损伤和修复以及肺癌的发病机制有关。肺上皮细胞通过尿激酶型(UPA)、尿激酶型受体(UPAR)和纤溶酶原激活物抑制物-1(PAL-1)参与血管外纤维蛋白重塑。这些分子在肺损伤和肿瘤中的异常表达扰乱了局部纤维蛋白的周转，加重了局部炎症，并促进了过渡性纤维蛋白的组织，最终导致纤维化。我们最近发现，uPA可诱导肺上皮细胞表达uPAR。我们现在证明外源性uPA也可以通过这些细胞诱导uPA和PAI-1的表达。这些研究清楚地表明，肺上皮细胞通过目前知之甚少的新途径调节uPA-uPAR-PAI-1系统。我们的初步数据表明，转录后调控有助于uPA介导的自我诱导，以及uPAR和PAI-1的诱导。我们的中心假设是，uPA调节自身以及肺上皮细胞uPAR和PAI-1表达的新途径在急性肺损伤及其修复和肺癌的发病机制中起着至关重要的作用。我们的目标是阐明uPA诱导这些分子表达的调控机制。我们将通过四个具体目标实现这一目标。在目标1中，我们将确定uPA是否在转录或转录后水平诱导上皮细胞uPAR，并确定相关机制。在目标2中，我们将确定a-凝血酶阻断uPA介导的uPAR诱导的机制。在目标3和4中，我们将分别确定uPA诱导其自身和PAL-1在肺上皮细胞中表达的机制。我们将使用我们有经验的广泛的分子、免疫组织化学、蛋白质纯化和细胞培养技术来完成拟议的工作。这些研究将增加我们对肺上皮细胞调节uPA-uPAR-PAI-1系统的新机制的理解。这些信息可能会加速开发新的、基于机制的干预措施来治疗肺部疾病，包括急性肺损伤或肺肿瘤。

DESCRIPTION (provided by applicant): Disordered fibrin turnover and extravascular fibrin deposition have been implicated in the pathogenesis of lung injury and repair and lung cancer. Lung epithelial cells contribute to remodeling of extravascular fibrin by elaboration of urokinase (uPA), the urokinase receptor (uPAR) and plasminogen activator inhibitor-1 (PAl-1). Abnormal expression of these molecules in lung injury and neoplasia disrupts local fibrin turnover, potentiates local inflammation, and promotes organization of transitional fibrin with eventual fibrosis. We recently found that uPA induces expression of uPAR by lung epithelial cells. We now demonstrate that exogenous uPA also induces uPA and PAI-1 expression by these cells. These studies clearly show that lung epithelial cells regulate the uPA-uPAR-PAI-1 system by novel pathways about which little is currently understood. Our preliminary data show that posttranscriptional regulation contributes to uPA-mediated autoinduction as well as that of uPAR and PAI-1. Our central hypothesis is that novel pathways by which uPA regulates its own expression as well as that of uPAR and PAI-1 by lung epithelial cells are crucial in the pathogenesis of acute lung injury, its repair and lung cancer. Our objective is to elucidate the regulatory mechanisms by which uPA induces expression of these molecules. We will accomplish the objective in four specific aims. In Aim 1, we will determine if uPA induces epithelial cell uPAR at both transcriptional or posttranscriptional levels and define the responsible mechanisms. In Aim 2, we will determine the mechanism by which a-thrombin blocks uPA-mediated uPAR induction. In Aims 3 and 4, we will determine the mechanisms by which uPA induces its own expression as well as that of PAl-1, respectively, in lung epithelial cells. We will use a wide range of molecular, immunohistochemical, protein purification, and cell culture techniques with which we are experienced to complete the proposed work. These studies will increase our understanding of novel mechanisms by which the lung epithelium regulates the uPA-uPAR-PAI-1 system. This information could hasten the development of new, mechanism-based interventions for lung disorders, including acute lung injury or lung neoplasia.