TYPE I COLLAGEN REGULATION IN PULMONARY FIBROSIS

I型胶原过度堆积是纤维化的主要特征 肺部疾病，导致正常肺功能中断。这 I型胶原的增加可能是由于 激活或抑制肺内胶原形成的效应物质 成纤维细胞。我们长期以来一直对下列机制感兴趣 关键调控分子，如转化生长因子-节拍(转化生长因子-B) β)、前列腺素E2(PGE2)和维甲酸(RA)影响I型 胶原蛋白堆积。我们认为，对相互作用的审查 这些调停者之间将提出可能的策略来调节 I型胶原在肺内堆积。转化生长因子-β被激活 通过两个信号受体(I型)传递的信号转录 和类型II)，每个都包含细胞质丝氨酸-苏氨酸激酶结构域。 我们发现转化生长因子-β能刺激I型受体，而前列腺素E-2能抑制I型受体的表达 级别。这些发现可能在一定程度上解释了海平面持续上升 转化生长因子-β诱导的I型胶原形成及其选择性抑制作用 前列腺素E_2对肺成纤维细胞转化生长因子-β作用的影响我们已经克隆了第一型 转化生长因子-β受体启动子。在这项提案的第一部分，我们将 利用人类I型受体启动子鉴定基因 转化生长因子-β和前列腺素E_2调节I型受体启动子的机制 活动。随后，通过过度表达缺乏激酶的或野生型- I型受体基因，我们将表征它们之间的精确关系 I型受体表达和α1(I)启动子活性。使用 α1(I)胶原蛋白启动子的构建，我们计划鉴定顺式作用 介导I型血清白蛋白下降的因素和反式作用因素 PGE2和RA对胶原基因转录的影响。我们假设 前列腺素E_2抑制I型胶原形成和转化生长因子-β的作用 I受体的表达表明，PGE1类似物米索前列醇可能有 肺纤维化的治疗价值。值得注意的是，我们发现 米索前列醇抑制基础胶原和转化生长因子-β诱导的胶原形成 体外培养肺成纤维细胞。因此，作为这项提案的最后部分，我们 将决定泼尼松在接受或不接受免疫治疗的情况下的效果，或者 米索前列醇对肺纤维化患者胶原生物合成的影响 疾病。我们将通过测量前胶原来评估胶原的生物合成。 多肽、赖氨酸氧化酶活性和胶原代谢物。总体而言， SCOR提案的这一部分中概述的研究将提供关键 关于I型胶原在体内堆积的调控信息 肺纤维化。

Excess accumulation of type I collagen is key feature of the fibrosing lung diseases, causing disruption of normal pulmonary function. This increase in type I collagen likely results from a complex interplay of effector substances which activate or inhibit collagen formation by lung fibroblasts. We have a long-standing interest in the mechanisms whereby key regulatory molecules such as transforming growth factor-beat(TGF- beta), prostaglandin E2 (PGE2), and retinoic acid (RA) affect type I collagen accumulation. We believe that the examination of interactions between these mediators will suggest possible strategies for modulating type I collagen accumulation in the lung. TGF-beta activates transcription via signals transmitted by two signalling receptors (type I and type II), each containing cytoplasmic serine-threonine kinase domains. We found that TGF-beta stimulates and PGE2 inhibits type I receptor mRNA levels. These findings may explain, in part, the sustained elevation of type I collagen formation induced by TGF-beta and the selective inhibition of TGF-beta action on lung fibroblasts by PGE2. We have cloned the type I TGF-beta receptor promoter. In the first part of this proposal, we will employ the human type I receptor promoter to identify the genetic mechanisms whereby TGF-beta and PGE2 regulate type I receptor promoter activity. Subsequently, by over-expressing a kinase deficient or a wild- type I receptor cDNA, we will characterize the precise relation between type I receptor expression and alpha 1(I) promoter activity. Using an alpha 1(I) collagen promoter construct, we plan to identify the cis-acting elements and trans-acting factors which mediate the decrease in type I collagen gene transcription by PGE2 and RA. We hypothesize that the inhibitory effect of PGE2 on type I collagen formation and TGF-beta type I receptor expression indicates that misoprostol, a PGE1 analog, may have therapeutic value in pulmonary fibrosis. Notably, we found that misoprostol inhibited basal and TGF-beta-induced collagen formation by lung fibroblasts in vitro. Thus, as the final part of this proposal we will determine the effect of prednisone with or without immunotherapy, or misoprostol on collagen biosynthesis in patients with fibrosing lung diseases. We will assess collagen biosynthesis by measuring pro-collagen peptides, lysyl oxidase activity, and collagen metabolites. Overall, the studies outlined in this component of the SCOR proposal will provide key information regarding the modulation of type I collagen accumulation in pulmonary fibrosis.