Molecular Mechanism of PARC-Mediated Lung Fibrosis

描述(由申请人提供)：肺纤维化是慢性炎症过程和环境暴露的常见后果。几种细胞因子会导致肺部和其他器官的纤维化。许多实验室以前的报告表明，在动物模型中只靶向这些因素中的一种可能会改善纤维化，这表明纤维化的发展是一个高度整合的过程，靶向单一细胞因子可能成为一种重要的治疗选择。与普遍存在的细胞因子相比，靶向器官特异性促纤维化因子可能会导致更少的副作用。已有资料表明，肺和活化调节趋化因子PARC是最近发现的一种肺特异性CC趋化因子，它可能是一个独立的肺特异性关键因子，通过其双重作用：1)间接地通过吸引T细胞并刺激这些T细胞产生促纤维化细胞因子；2)直接通过激活肺成纤维细胞产生胶原蛋白。了解PARC直接促纤维化作用的机制是本研究的主题。本研究的具体假设是，PARC通过与特定的细胞表面受体结合，通过ERK通路发出信号，激活转录因子Sp1，激活胶原的转录，最终导致肺纤维化，从而激活人肺成纤维细胞的胶原生成。为了验证这一假设，我们将探讨以下具体目标： 1.鉴定肺成纤维细胞上的PARC特异性受体(S)，确定是否有其他分子参与PARC的结合，并研究PARC与其受体(S)的结合动力学。 2.研究PARC对肺成纤维细胞中ERK通路和Sp1的激活作用，确定肺成纤维细胞中Sp1的活化是否由ERK通路介导。确定ERK和SP1激活在ParC刺激的肺成纤维细胞胶原生成中的作用。 3.利用胶原启动子的缺失结构，定位参与PARC对胶原转录调控的反应元件。确定增加的mRNA稳定性是否也有助于ParC刺激的胶原生成的上调。 4.分析肺腺病毒载体介导的PARC基因转移对完整小鼠肺和博莱霉素组小鼠肺纤维化的影响。

DESCRIPTION (provided by applicant): Lung fibrosis is a frequent consequence of chronic inflammatory processes and environmental exposures. Several cytokines contribute to fibrosis in the lungs and other organs. Previous reports from numerous laboratories indicate that targeting only one of these factors may ameliorate fibrosis in animal models, suggesting that development of fibrosis is a highly integrated process, and that targeting of a single cytokine may become an important therapeutic option. Targeting organ-specific profibrotic factors may lead to fewer side effects than targeting ubiquitous cytokines. Available data suggest that pulmonary and activation-regulated chemokine, PARC, a recently discovered lung-specific CC chemokine, may be an independent lung-specific key factor contributing to lung fibrosis through its dual action - 1) indirectly by attracting T cells and stimulating production of profibrotic cytokines from these T cells, and 2) directly by activating collagen production from lung fibroblasts. Understanding mechanisms of the direct profibrotic effect of PARC is the subject of this study. The specific hypothesis of this study is that PARC activates collagen production in human lung fibroblasts by binding to a specific cell surface receptor, signaling through the ERK pathway, activating transcription factor Sp1, activating transcription of collagen, and finally causing lung fibrosis. To test this hypothesis, the following Specific Objectives will be addressed: 1. Identify the PARC-specific receptor(s) on lung fibroblasts, determine whether other molecules are involved in PARC binding, and characterize the binding kinetics of PARC to its receptor(s). 2. Characterize activation of the ERK pathway and Sp1 in lung fibroblasts by PARC and establish whether PARC-dependent activation of Sp1 is mediated by the ERK pathway. Determine the role of ERK and SP1 activation in PARC-stimulated collagen production in lung fibroblasts. 3. Using deletion constructs of the collagen promoter, locate response elements involved in transcriptional regulation of collagen by PARC. Determine whether increased mRNA stability also contributes to PARC-stimulated upregulation of collagen production. 4. Analyze the effects of pulmonary adenovector-mediated gene transfer of PARC on lung fibrosis in intact mouse lung and bleomycin-treated mouse lung.