Role of TET1 in airway epithelium and childhood asthma

项目摘要 哮喘是儿童中最常见的慢性疾病，也是急诊护理的主要原因， 儿童住院。尽管存在多种哮喘疗法，但哮喘患者的不完全疗效率很高， 哮喘治疗（40%-70%）强调了基于更好的非- 了解疾病机制。迄今为止，病因学和病理学基础的分子机制- 儿童哮喘的病因尚未完全清楚。这一建议直接填补了这一知识空白， 测试了一种新的疾病机制假说。甲基胞嘧啶双加氧酶TET 1修饰5 '- 甲基胞嘧啶和调节基因功能。除了其催化活性，TET 1蛋白招募组蛋白 通过与转录因子（TF）相互作用修饰蛋白质复合物以调节组蛋白标记， 染色质可及性，导致基因表达的激活和抑制。我们是第一个 在气道上皮细胞中，较高的TET 1启动子甲基化与较低的TET 1表达相关， 儿童哮喘症状更常见。此外，我们发现TET 1在HBECs（人）中的过表达 支气管上皮细胞）导致干扰素（IFN）信号传导途径的转录下调。组成- 最终，HBEC中TET 1的缺失显著增加了IRF 7及其下游靶I型的表达， HDM激发后的IFN。最后，Tet 1的缺失导致IFN信号通路的肺表达增加- 方法，并导致哮喘小鼠模型气道高反应性和肺部炎症增强。 总的来说，这些数据支持TET 1通过抑制I型哮喘的严重程度而发挥整体保护作用。 IFN信号传导。我们的数据强烈地暗示了蛋白质/蛋白质相互作用网络，包括IRF 7/STAT 1/STAT 2， 介导TET 1对I型IFN诱导的作用。初步分析支持IRF 7前体的调节， TET 1通过DNA甲基化和组蛋白修饰表达。众所周知，气道上皮细胞- al I型IFN信号通路调节对外部刺激和con的先天性和适应性免疫反应 哮喘的发展和恶化。总的来说，我们假设Tet 1调节哮喘 表型通过抑制I型干扰素信号通过DNA甲基化和组蛋白修饰在空气中， 方式上皮细胞。我们的长期目标是了解儿童哮喘的表观遗传调控。的 R 01申请的目的是确定TET 1导致哮喘的机制。这个ap- 将对公众健康产生重大影响。通过拟议的目标，我们将1）证明， 气道上皮TET 1对I型IFN信号通路的转录调节哮喘phe- 2）定义TET 1调节正常和非正常细胞中I型IFN信号通路的机制， 哮喘上皮; 3）显示Tet 1调节呼吸道病毒诱导的哮喘恶化;和4）促哮喘发作， 为哮喘和其他疾病提供了新的治疗靶点，其中I型IFN信号通路是一种es- sential玩家

Project Summary Asthma is the most common chronic disease among children and the leading cause of emergency care and hospitalization in children. Even though multiple asthma therapies exist, the high rate of incomplete efficacy in asthma treatment (40%-70%) highlights the need for alternative individualized therapies based on a better un- derstanding of disease mechanisms. To date, the molecular mechanisms underlying the etiology and patho- genesis of childhood asthma are not fully understood. This proposal directly fills in this gap in knowledge and tests a novel hypothesis addressing disease mechanism. Methylcytosine dioxygenase TET1 modifies 5’- methyl-cytosine and regulate gene function. In addition to its catalytic activity, TET1 protein recruits histone modifying protein complexes through interaction with transcription factors (TFs) to regulate histone marks and chromatin accessibility, leading to both activation and repression of gene expression. We were the first to show that in airway epithelial cells, higher TET1 promoter methylation is associated with lower TET1 expression and more frequent asthma symptoms in children. Further, we found that overexpression of TET1 in HBECs (human bronchial epithelial cells) leads to transcriptional downregulation of interferon (IFN) signaling pathway. Consist- ently, loss of TET1 in HBECs significantly increases the expression of IRF7 and its downstream target type I IFN following HDM challenges. Finally, loss of Tet1 causes increased lung expression of IFN signaling path- way and leads to enhanced airway hyperresponsiveness and lung inflammation in mouse models of asthma. Collectively, these data support an overall protective role of TET1 in asthma severity through inhibition of type I IFN signaling. Our data strongly implicate a protein/protein interaction network including IRF7/STAT1/STAT2 in mediating the effects of TET1 on type I IFN induction. Preliminary analysis supports the regulation of IRF7 ex- pression by TET1 through DNA methylation and histone modification. It is well established that airway epitheli- al type I IFN signaling pathway regulates innate and adaptive immune responses to external stimuli and con- tributes to asthma development and exacerbation. Collectively, we hypothesize that Tet1 regulates asthma phenotypes by inhibiting type I interferon signaling through DNA methylation and histone modifications in air- way epithelial cells. Our long-term goal is to understand the epigenetic regulation of childhood asthma. The objective of this R01 application is to identify the mechanism(s) by which TET1 contributes to asthma. This ap- plication will have significant public health impact. Through the proposed aims, we will 1) demonstrate that the transcriptional regulation of type I IFN signaling pathway by TET1 in airway epithelium modulates asthma phe- notypes; 2) define the mechanism(s) by which TET1 regulates type I IFN signaling pathway in normal and asthmatic epithelium; 3) show that Tet1 regulates respiratory virus-induced asthma exacerbation; and 4) pro- vide novel therapeutic targets for asthma and other diseases in which type I IFN signaling pathway is an es- sential player.