Role of Smad3 in obiliterative bronchiolitis

描述(由申请人提供)： 闭塞性毛细支气管炎(OB)被认为是肺移植受者慢性移植物功能障碍的一种表现，是一种不可逆转的纤维增殖过程，是长期生存的主要障碍。因此，研究旨在确定参与肺移植受者OB发生的因素，对于找到这种无法治愈的疾病的有效治疗至关重要。我们发现转化生长因子-p(TGFp)通过其信号转导因子SMADS在OB的发生和伴随OB的肌成纤维细胞转分化过程中是必需的。因此，我们重点研究了OB中TGFp/Smad信号的调控机制，并进行了一些关键的观察。首先，细胞外半胱氨酸-半胱氨酸(Cys/Cyss)氧化还原偶联的氧化诱导TGFp和SrnadS的上调和激活。第二，Smads在肺成纤维细胞中的表达和DNA结合，从而促进了肌成纤维细胞的转化，异常的过渡基质，如纤维连接蛋白和I型胶原，这些成分总是在OB的背景下发现的。第三，激活核转录因子--过氧化物酶体增殖物激活受体-y(PPARy)，通过干扰Smads依赖的基因转录，抑制TGFp1诱导的肌成纤维细胞转分化。这些发现导致我们假设，TGFp1/Smad3信号在气道成纤维细胞中的激活是OB肌成纤维细胞转分化的关键驱动因素，慢性细胞外氧化应激、异常的过渡基质和PPARy信号缺陷的存在会加剧这种转分化。这一假说将在成纤维细胞培养和OB实验模型中进行验证，目的有三个特定的目的：1)检测慢性细胞外氧化应激通过Cys/CySS氧化还原偶联激活体内外依赖TGFp1/Smad3的信号事件的机制2)检测过渡基质如何通过整合素依赖的信号促进TGFp1/Smads信号的激活和肌成纤维细胞的转分化3)确定PPARy影响Smads信号通路以及诱导实验性OB肌成纤维细胞转分化和基质表达的机制。这些复杂的问题将在专家顾问和合作者的协助下解决，其更广泛的目标是揭示治疗的新靶点。 (摘要结束)

DESCRIPTION (provided by applicant): Obliterative bronchiolitis (OB), considered to be a manifestation of chronic allograft dysfunction in lung transplant recipients, is an irreversible fibroproliferative process that represents the major barrier to long term survival. Hence, research directed at identifying the factors involved in the development of OB in lung transplant recipients is paramount to finding effective treatment for this otherwise untreatable disease. We have found that Transforming Growth Factor-p (TGFp) via its signal transducer, SmadS, is necessary for the development of OB as well as the myofibroblast transdifferentiation that accompanies OB. Hence, we have focused on the mechanisms regulating TGFp/Smad signaling in OB and have made a number of key observations. First, oxidation of the extracellular cysteine-cystine (Cys/CySS) redox couple induces upregulation and activation of TGFp and SrnadS. Second, SmadS expression and DNA binding in lung fibroblasts, and consequently, myofibroblast transformation, is augmented by aberrant transitional matrix, components, e.g., fibronectin and type I collagen, which are invariably found in the setting of OB. And third, activation of the nuclear transcription factor, peroxisome proliferator-activated receptor-y (PPARy), inhibits TGFpl -induced myofibroblast transdifferentiation by disrupting SmadS-dependent gene transcription. These findings led us to the hypothesis that activation of TGFp1/Smad3 signaling in airway fibroblasts is a critical driver of myofibroblast transdifferentiation in OB that is intensified by the presence of chronic extracellular oxidant stress, aberrant transitional matrices, and defective PPARy signaling. This hypothesis will be tested in fibroblast cultures and in experimental models of OB in three specific aims designed to: 1) examine the mechanisms by which chronic extracellular oxidative stress activates TGFp1/Smad3-dependent signaling events in vitro and in vivo through the Cys/CySS redox couple 2) examine how transitional matrices promote activation of TGFpl /SmadS signaling and myofibroblast transdifferentiation through integrin-dependent signals 3) determine the mechanisms by which PPARy affects the SmadS signaling pathway and the induction of myofibroblast transdifferentiation and matrix expression in experimental OB. These complex issues will be addressed with the assistance of expert advisors and collaborators with the broader objective of unveiling novel targets for therapy. (End of Abstract)