HL-FAM13A Regulates the beta-catenin/Wnt Pathway in Chronic Obstructive Pulmonary Disease

 描述（由申请人提供）：HL-131。慢性阻塞性肺疾病（COPD）是美国第三大死亡原因，它也受到吸烟（CS）和遗传易感性的强烈影响。一个新的基因，FAM13A（家族序列相似性13，成员A，功能未知）一直与COPD的易感性在病例对照研究和肺功能在一般人群样本的全基因组关联研究（GWAS）。最近，FAM13A基因座处的COPD风险等位基因显示与人肺样品中FAM13A的表达增加相关。然而，这种新的基因如何在体内CS诱导的损伤下发挥作用仍然未知。我们知识中的这一巨大差距极大地阻碍了这些遗传学发现转化为更好地理解COPD病理生物学和个性化医疗的巨大潜力。使用一系列在体外和体内的方法，我们证明，Fam13a-/-小鼠（Fam13a-/-）显示减弱肺气肿引起的CS或弹性蛋白酶。我们还首次将新型GWAS基因FAM13A与经典Wnt通路联系起来，该通路对于肺发育以及各种肺部疾病中的肺修复/再生至关重要。在体外，Fam13a促进蛋白磷酸酶2A（PP2A）与β-连环蛋白的组装，并促进β-连环蛋白的磷酸化和降解.在此，我们建议将我们的研究扩展到Fam13a对Wnt通路的调节以及它们的串扰如何在CS诱导的损伤期间介导肺修复的深入和全面的解剖。在目标1中，我们将利用敏感且特异的GFP报告小鼠系用于Wnt途径活化以表征在CS暴露期间Fam13a对Wnt途径活性的时间和空间调节。在目标2中，我们将充分表征Fam13a如何通过抑制CS诱导的损伤模型中的Wnt通路来调节肺再生。在目的2.1中，我们将特异性地在SP-C（表面活性蛋白C）阳性细胞、兼性祖细胞中产生双缺陷（Fam13a和β-连环蛋白）小鼠系，用于损伤后的肺通气，然后将这些小鼠暴露于CS，以确定Wnt通路的激活是否导致Fam13a-/-小鼠对CS诱导的肺通气扩大的抵抗。SP-C阳性细胞在CS诱导损伤后肺再生中的作用将在目标2.2中进一步探讨。我们将在体内存在或不存在Fam13a的情况下，在他莫昔芬诱导后用GFP示踪标记SPC阳性细胞，然后将小鼠暴露于急性和慢性CS以确定Fam13-Wnt轴在SPC阳性细胞介导的肺再生中的作用。在目标3中，我们将应用来自COPD受试者的人原代肺泡和气道上皮细胞，其在FAM13A基因座具有已知基因型，以确定差异细胞增殖和分化是否与FAM13A基因型相关的不同β-连环蛋白水平相关。本项目完成后，我们将对Fam13 a-catenin/Wnt通路在CS诱导的损伤中的作用以及人类COPD的潜在机制有更深入的了解。

 DESCRIPTION (provided by applicant): HL-131. Chronic obstructive pulmonary disease (COPD) is the third leading cause of death in the U.S. It is also strongly influenced by cigarette smoking (CS) and genetic predisposition. A novel gene, FAM13A (family with sequence similarity 13, member A, with unknown function) has been consistently associated with susceptibility to COPD in case-control studies and with lung function in general population samples in genome-wide association studies (GWAS). Very recently, the COPD risk allele at the FAM13A locus was shown to be associated with increased expression of FAM13A in human lung samples. However, how this novel gene functions in vivo under CS-induced injury remains unknown. This substantial gap in our knowledge has greatly impeded translation of these genetic discoveries into a better understanding of COPD pathobiology and the huge potential of personalized medicine. Using a series of in vitro and in vivo approaches, we demonstrate that Fam13a-deficient mice (Fam13a-/-) showed attenuated emphysema induced by either CS or elastase. We also make the first connection between the novel GWAS gene FAM13A and the canonical Wnt pathway, essential for lung development as well as lung repair/regeneration in a variety of pulmonary diseases. In vitro, Fam13a facilitates assembly of protein phosphatase 2A(PP2A) with ß-catenin and promotes the phosphorylation and degradation of ß-catenin. Herein, we propose to extend our studies to a deep and comprehensive dissection of the regulation of the Wnt pathway by Fam13a and how their cross-talk mediates lung repair during CS-induced injury. In Aim 1, we will utilize a sensitive and specific GFP reporter mouse line for Wnt pathway activation to characterize the temporal and spatial regulation of Fam13a on the activity of the Wnt pathway during CS- exposure. In Aim 2, we will fully characterize how Fam13a modulates lung regeneration through inhibiting the Wnt pathway in the CS-induced injury model. In Aim 2.1,we will generate a double-deficient (Fam13a and ß- catenin) mouse line specifically in SP-C(surfactant protein C)-positive cells, facultative progenitor cells for lung reair after injury and then expose these mice to CS to determine whether activation of the Wnt pathway led to resistance to CS-induced airspace enlargement in Fam13a-/- mice. Roles of SP-C-positive cells in lung regeneration after CS-induced injury will be further explored in Aim 2.2. We will trace-label SPC-positive cells with GFP after tamoxifen induction in the presence or absence of Fam13a in vivo, then expose mice to acute and chronic CS to determine the role of the Fam13-Wnt axis in lung regeneration mediated by SPC-positive cells. In Aim 3, we will apply human primary alveolar and airway epithelial cells from COPD subjects with known genotypes at the FAM13A locus to determine whether differential cell proliferation and differentiation correlate with varying beta-catenin levels associated with FAM13A genotypes. Upon completion of this project, we will have a much deeper understanding of the role of Fam13a-ß-catenin/Wnt pathway during CS-induced injury and the mechanisms underlying human COPD.