ELASTOGENIC RESPONSES TO LUNG INJURY

弹性蛋白是一种细胞外蛋白，其固有的在气体和液体压力梯度下被动膨胀和收缩的能力使其成为维持正常肺功能的重要功能元素。在肺气肿等阻塞性疾病中，肺泡壁弹性蛋白的持续丢失伴随着空气空间的扩大是病理过程中的一个重要因素。从体外和体内弹性酶损伤模型中获得的证据表明，弹性酶损伤后不溶性弹性蛋白增加，弹性蛋白mRNA水平上调。提供的初步数据显示，对携带弹性蛋白启动子转基因的小鼠经气管内注射弹性蛋白酶会导致弹性蛋白启动子活性增加以及弹性蛋白mRNA水平增加。这个项目的总体目标是阐明弹性蛋白基因转录上调的潜在机制，并研究这些机制在弹性蛋白酶诱导的弹性蛋白修复中的作用。我们的假设是，弹性酶诱导的降解依赖于它们对弹性酶损伤的接近程度。已发表的数据显示，弹性蛋白基因启动子中的两个顺式作用元件(NF1和Sp1/Sp3位点)调节弹性蛋白转录的增加。这两个区域都与弹性蛋白基因表达上调有关，在从增殖到停滞的肺成纤维细胞和平滑肌细胞以及在弹性蛋白酶处理的肺成纤维细胞中，弹性蛋白基因表达上调。针对总体假设，本文提出了四个具体目标。1.探讨肺弹力细胞弹性蛋白基因表达上调的机制。2.确定在未经处理和弹性蛋白酶处理的细胞培养中调节弹性蛋白转录的基因。3.研究肺成纤维细胞和血管平滑肌细胞对弹性蛋白酶局部释放的反应。4.体内检测弹性蛋白基因启动子对弹力酶诱导的肺损伤的反应。总体而言，这些研究应该提供关于调节弹性蛋白基因转录的顺式元件和反式作用因子及其在修复反应中的作用的重要信息。此外，转录机制的阐明应该为COPD的早期治疗提供策略，在COPD的早期阶段，弹性蛋白的重新合成可能是决定疾病进展的关键事件。

Elastin is an extracellular protein whose intrinsic ability to passively expand and contract under gas and liquid pressure gradients renders it an important functional element in maintaining proper pulmonary function. In pulmonary obstructive diseases such as emphysema, the continual loss of elastin from alveolar walls concomitant with enlargement of air spaces is a significant factor in the pathological process. Evidence obtained from both in vitro and in vivo models of elastase injury demonstrate that insoluble elastin is increased and elastin mRNA levels are up-regulated after elastase damage. Preliminary data supplied show that intratracheal administration of elastase to mice carrying the elastin promoter transgene results in an increase in elastin promoter activity as well as an increase in elastin mRNA levels. The overall objective of this project is to elucidate the mechanisms underlying up-regulation of elastin gene transcription and examine these mechanisms in elastase- induced elastin repair. Our hypothesis is that elastase-induced degradation dependent on their proximity to elastase injury. Published data show that two cis-acting elements (NF1 and Sp1/Sp3 sites) within the elastin gene promoter modulate increases in elastin transcription. Both of these areas are implicated in the up-regulation of elastin gene expression seen in the transition from proliferative to arrested pulmonary fibroblasts and smooth muscle cells and in elastase treated pulmonary fibroblasts smooth muscle cells. Four specific aims are proposed to address the overall hypothesis. 1. Determine the mechanisms involved in the up-regulation of elastin gene expression in pulmonary elastogenic cells. 2. Identify genes that modulate elastin transcription in untreated and elastase treated cell cultures. 3. Characterized the response of pulmonary fibroblasts and smooth muscle cells to localized delivery of elastase. 4. Determine the response of the elastin gene promoter to elastase-induced lung injury in vivo. Overall these studies should provide important information concerning the cis-elements and trans- acting factors that regulate elastin gene transcription and their role in repair responses. Further, the elucidation of transcriptional mechanisms should provide strategies for Treatment in early stages of COPD where the re-synthesis of elastin may be critical event in determining the progression of the disease.