Role of p53 and PAI-1 in tobacco smoke exposure induced lung injury

 描述(申请人提供)：接触烟草烟雾(TS)会损害肺上皮细胞，并导致慢性阻塞性肺疾病(COPD)，这是美国第四大死亡原因。我们和其他人的发现表明，环境中被动的TS暴露导致的肺损伤包括程序性肺泡上皮细胞死亡和异常的纤维蛋白周转。在这个项目中，我们将确定导致上皮细胞死亡的蛋白质P53如何调节纤溶酶原激活物抑制物-1(PAI-1)，后者是血液凝块溶解系统的抑制物，从而影响肺上皮细胞的活性。肺泡PAI-1的表达增加导致局部纤溶受到抑制，并促进广泛的纤维蛋白沉积，这是几乎所有形式的肺损伤的特征，包括环境TS暴露引起的肺损伤。肺泡II型上皮细胞(ATII细胞)的凋亡，由肿瘤抑制蛋白P53介导，同样与TS诱导的肺损伤(如COPD)的发病机制独立相关。ATII细胞是肺部PAI-1的主要来源，也表达P53。我们最近提出的证据表明，在受损的ATII细胞中诱导P53上调PAI-1mRNA和蛋白的表达。我们最近的研究表明，暴露在环境或被动TS中与P53和PAI-1表达的不成比例增加有关，抑制ATII细胞中的P53或PAI-1可以减轻细胞凋亡。缺乏P53或PAI-1表达的小鼠ATII细胞不发生TS暴露诱导的凋亡，而野生型小鼠ATII细胞显示P53和PAI-1表达增加和凋亡。这些新认识的相互作用如何在TS诱导的肺损伤的发病机制中起作用尚不清楚。我们的项目解决了这一关键差距。我们将使用一系列分子和新的干预方法，包括使用基因敲除小鼠来解决我们的工作假设，即P53介导的PAI-1表达增加促进ATII细胞凋亡。这在TS肺损伤的发病机制中起中心作用，并可被小窝蛋白-1支架肽(CSP)逆转，为这种肺损伤提供了一种新的干预方法。我们的目的是确定CSP如何通过靶向P53介导的PAI-1表达和ATII细胞凋亡来改善TS诱导的肺损伤。1)阐明CSP在TS肺损伤中调节P53诱导的PAI-1表达和ATII细胞凋亡的机制。2)探讨CSP逆转TS诱导的MicroRNA-34a和表面活性蛋白-C表达变化对ATII细胞凋亡和肺损伤的影响。我们将使用小鼠WT、P53-/-和PAI-1-/-模型阐明P53诱导的PAI-1如何影响TS暴露引起的肺泡损伤。这个项目将通过阐明P53介导的PAI-1的诱导如何调节ATII细胞的活性和调节肺损伤的结果来推动这一领域的发展。拟议的介入研究还可能定义新的、药理学上有针对性的方法，以改善因环境TS暴露而导致的肺损伤患者的临床结果。

 DESCRIPTION (provided by applicant): Tobacco smoke (TS) exposure damages to lung epithelium and leads to chronic obstructive pulmonary disease (COPD), the fourth leading cause of death in the United States. Our findings and those of others suggest that environmental, passive TS exposure induced lung injury involves programmed alveolar epithelial cell death and abnormal fibrin turnover. In this project, we will determine how p53, a protein causing epithelial cell death, regulates plasminogen activator inhibitor-1 (PAI-1), an inhibitor of the blood clot dissolution system, to influence the viability of the lung epithelium. Increased alveolar expression of PAI-1 results in locally suppressed fibrinolysis and promotes the extensive fibrin deposition that characterizes virtually all forms of lung injuries, including those caused by environmental TS exposure. Alveolar type II epithelial cell (ATII cell) apoptosis, mediated by the tumor suppressor protein, p53, is likewise independently linked to the pathogenesis of TS-induced lung injuries such as COPD. ATII cells are a major source of PAI-1 in the lungs and also express p53. We recently presented evidence indicating that induction of p53 in injured ATII cells up-regulates both PAI-1 mRNA and protein expression. Our recent studies indicated that exposure to environmental or passive TS is linked to a disproportionate increase in p53 and PAI-1 expression and that inhibition of either p53 or PAI-1 in ATII cells mitigates apoptosis. ATII cells of mice lacking either p53 or PAI-1 expression do not undergo TS exposure-induced apoptosis, whereas ATII cells from wild-type mice show increased p53 and PAI-1 expression and apoptosis. How these newly recognized interactions contribute to the pathogenesis of TS-induced lung injury is unclear. Our project addresses this critical gap. We will use a range of molecular and novel interventional approaches that include the use of knockout mice to address our working hypothesis, which is that p53-mediated increase in expression of PAI-1 promotes ATII cell apoptosis. This is central to the pathogenesis of TS-induced lung injury and can be reversed by caveolin-1 scaffolding peptide (CSP), offering a novel interventional approach for this form of lung injury. Our objective is to determine how CSP improves TS-induced lung injury by targeting p53-mediated PAI-1 expression and ATII cell apoptosis. Our Specific Aims are: 1) to elucidate the mechanism by which CSP modulates p53-induced PAI-1 expression and ATII cell apoptosis during TS-induced lung injury. 2) to determine how reversal of TS-induced changes in the expression of microRNA-34a and surfactant protein-C by CSP mitigates ATII cell apoptosis and lung injury. We will illuminate how p53-induced PAI-1 affects alveolar injury caused by TS exposure using murine WT, p53-/- and PAI-1-/- models. This project will advance the field by elucidating how p53-mediated induction of PAI-1 regulates ATII cell viability and modulates the outcome of lung injury. The proposed interventional studies may also define new, pharmacologically targeted approaches to improve clinical outcomes for patients with lung injuries due to environmental TS exposure.