ELASTOGENIC RESPONSES TO LUNG INJURY

弹性蛋白是一种细胞外蛋白，其在气体和液体压力梯度下被动扩张和收缩的内在能力使其成为维持适当肺功能的重要功能元件。在肺阻塞性疾病如肺气肿中，肺泡壁弹性蛋白的持续损失伴随着空气空间的扩大是病理过程中的重要因素。从体外和体内弹性蛋白酶损伤模型中获得的证据表明，弹性蛋白酶损伤后，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，向携带弹性蛋白启动子转基因的小鼠腹膜内施用弹性蛋白酶导致弹性蛋白启动子活性增加以及弹性蛋白mRNA水平增加。本课题的主要目的是阐明弹性蛋白基因转录上调的机制，并研究弹性蛋白酶诱导的弹性蛋白修复机制。我们的假设是，弹性蛋白酶诱导的降解依赖于他们接近弹性蛋白酶损伤。已发表的数据表明，弹性蛋白基因启动子内的两个顺式作用元件（NF 1和Sp1/Sp3位点）调节弹性蛋白转录的增加。这两个区域都涉及弹性蛋白基因表达的上调，在从增殖到停滞的肺成纤维细胞和平滑肌细胞的转变中以及在弹性蛋白酶处理的肺成纤维细胞平滑肌细胞中观察到。提出了四个具体目标来解决总体假设。1.确定肺弹性细胞中弹性蛋白基因表达上调的机制。2.在未处理和弹性蛋白酶处理的细胞培养物中鉴定调节弹性蛋白转录的基因。3.表征肺成纤维细胞和平滑肌细胞对弹性蛋白酶局部递送的反应。4.测定弹性蛋白基因启动子对弹性蛋白酶诱导的肺损伤的体内反应。总的来说，这些研究应该提供重要的信息，顺式元件和反式作用因子，调节弹性蛋白基因转录和修复反应中的作用。此外，转录机制的阐明应该为COPD早期阶段的治疗提供策略，其中弹性蛋白的再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.