DNA-Damage Repair In Pulmonary Fibrosis

 描述(申请人提供)：多达20%的特发性肺纤维化病例(IPF)是家族性的，包括一种称为家族性间质性肺炎(FIP)的综合征。外周血液端粒长度较短与散发性IPF和FIP有关，在15-20%的FIP家系中发现了罕见的端粒酶复合体基因功能缺失突变，然而，迄今为止关于端粒酶功能障碍和端粒缩短与肺纤维化之间联系的机制的研究在很大程度上尚未揭示。利用全外显子测序，我们最近在15个FIP家系中发现了与疾病分离的端粒延伸解旋酶调节因子(RTEL1)功能缺失突变，我们的初步数据表明，RTEL1功能受损导致肺泡上皮细胞(AECs)DNA损伤修复效率低下，导致P53介导的细胞周期停滞信号程序激活，这可能导致肺纤维化背景下AEC功能障碍。利用生物信息学方法，我们鉴定了一大群FIP家族(&gt；50%)，这些家族携带与细胞周期、DNA损伤修复和P53信号相关的其他基因的罕见变异，这表明这些相互关联的通路的异常可能是FIP家族大亚群的遗传风险的基础。在这个方案中，我们假设FIP相关基因(包括RTEL1)功能丧失的遗传变异通过改变DNA损伤修复和激活P53介导的细胞周期检查点停止信号而易患肺纤维化，导致损伤后的再上皮化受损和进行性纤维化重塑。我们的具体目标是：(1)确定rtel在实验性肺纤维化中的作用。(2)确定RTEL1调节DNA损伤修复和细胞存活/增殖的机制；(3)确定FIP家族和散发性IPF患者的DNA损伤修复能力是否发生改变。为了实现这些目标，我们将利用RTEL缺陷小鼠模型、RTEL1缺陷细胞系、RTEL1缺陷小鼠的原代细胞以及FIP和IPF患者的原代细胞。总之，这些研究有望阐明DNA损伤修复和信号在肺纤维化发展中的作用，从而为疾病发病机制提供重要的新见解。

 DESCRIPTION (provided by applicant): Up to 20% of idiopathic pulmonary fibrosis cases (IPF) are familial, comprising a syndrome known as Familial Interstitial Pneumonia (FIP). Short peripheral blood telomere length has been associated with sporadic IPF and FIP, and rare loss of function mutations in telomerase complex genes have been found in 15-20% of FIP families, however, investigations to date regarding the mechanisms linking telomerase dysfunction and telomere shortening with lung fibrosis have been largely unrevealing. Using whole-exome sequencing, we have recently identified loss-of-function mutations in regulator of telomere elongation helicase (RTEL1) that segregated with disease in 15 FIP families, and our preliminary data suggest impaired RTEL1 function leads to inefficient repair of DNA-damage in alveolar epithelial cells (AECs), leading to activation of p53 mediated cell- cycle arrest signalin programs that may contribute to AEC dysfunction in the context of pulmonary fibrosis. Using bioinformatics approaches, we identified a large group of FIP families (>50%) that carry rare variants in other genes related to cell cycle, DNA damage-repair, and p53 signaling, suggesting that abnormalities in these interrelated pathways may underlie genetic risk for a large subset of FIP families. In this proposal, we hypothesize that loss-of-function genetic variants in FIP-associated genes (including RTEL1) predispose to pulmonary fibrosis by altering DNA-damage repair and activating p53-mediated cell-cycle checkpoint arrest signaling in alveolar epithelial cells, resulting in impaired re-epithelialization following injury and progressive fibrotic remodeling. Our specific aims are: (1) To determine the role of Rtel in experimental lung fibrosis. (2) To determine the mechanisms through which RTEL1 regulates DNA damage-repair and cell survival/proliferation in response to injury, and (3) To determine whether DNA damage-repair capacity is altered in a large subset of FIP families and patients with sporadic IPF. To accomplish these aims, we will utilize Rtel deficient mouse models, RTEL1 deficient cell lines, primary cells from Rtel deficient mice, and primary cells from FIP and IPF patients. Together, these studies hold the promise of elucidating the role of DNA-damage repair and signaling in the development of pulmonary fibrosis, thus adding important new insights into disease pathogenesis.