TET1-mediated 5-hydroxymethylcytosine modification & airway hyperresponsiveness

 描述（由申请人提供）：哮喘是一种以气道高反应性（AHR）和气道炎症为特征的复杂疾病，目前困扰着全球超过3亿人。虽然遗传因素无疑在哮喘中起作用，但哮喘患病率的迅速上升表明环境因素可能起着同样重要的作用。到目前为止，表观遗传调节被认为至少部分地介导了可能导致哮喘的复杂的基因与环境的相互作用。迄今为止，大多数研究集中在阐明容易接近的细胞（包括T细胞和B细胞）中的DNA甲基化模式， 解释哮喘患者过敏原致敏的免疫学机制。很少有研究探讨了与肺功能慢性改变有关的肺组织环境触发因素的表观遗传后果。我们已经利用下一代测序技术和适当的验证分析，以确定一组新的基因，这是高度富集的Tgfb 2信号分子，并与暴露于常见的过敏原，屋尘螨（HDM），并通过气道平滑肌（ASM）细胞表型的表观遗传调节AHR的发展。此外，我们确定了一种新的作用，具体的5-mC双加氧酶，TET 1，在体外调节ASM功能和过敏原驱动的AHR在体内的发展。首先，我们证明Tet 1缺陷减少小鼠中急性HDM驱动的AHR。引人注目的是，我们能够翻译人类哮喘ASM细胞中的表观遗传变化;显示Tet 1介导的羟甲基化可能影响ASM细胞增殖和收缩。我们的研究首次证明Tet 1蛋白在过敏原暴露的背景下受到调节，尽管过敏原对Tet 1诱导的调节机制尚不清楚。我们的初步数据支持HDM暴露产生的氧化应激激活Tet 1及其介导的ASM基因上调。基于这些新的发现，我们提出了中心假设“HDM通过调节氧化还原循环激活ASM细胞中Tet 1介导的羟甲基化。这种表观遗传重编程在ASM中持续了很长一段时间，因此可能有助于在人类哮喘中观察到的ASM细胞增殖，僵硬和收缩性增加。为了解决这些新的假设，我们组建了一个多学科的研究人员团队，他们拥有广泛的专业知识，涵盖表观遗传学，ASM生物学，肺病学和病理生物学领域。首先，我们将在慢性HDM诱导的AHR小鼠模型中确定Tet 1介导的DNA羟甲基化在AHR表型发展中的作用。其次，我们将研究HDM如何改变Tet 1活性，通过在体外和体内小鼠模型中的NADH的氧化还原循环。最后，我们将确认TET 1介导的羟甲基化是否调节人ASM细胞表型。这些实验结果将为研究ASM及其在哮喘气道过度狭窄中的作用提供新的视角。这些见解可能会推动新的治疗方法的发展，用于治疗这种使人衰弱的疾病。

 DESCRIPTION (provided by applicant): Asthma is a complex disease characterized by airway hyperresponsiveness (AHR) and airway inflammation, which current afflicts over 300 million people worldwide. Although genetic factors unquestionably play a role in asthma, the rapid rise in asthma prevalence suggests that environmental factors likely play an equally important role. To date, epigenetic regulation is suggested to mediate, at least partly, the complex gene-by- environment interactions that can lead to asthma. Most studies to date have focused on elucidation of DNA methylation patterns in easily accessible cells including T cells and B cells to explain the immunological mechanisms driving allergen sensitization in asthmatics. Few studies have examined the epigenetic consequences of environmental triggers on lung tissues linked to chronic alterations in lung functions. We have utilized next generation sequencing techniques and proper validation assays to identify a novel set of genes which is highly enriched for Tgfb2 signaling molecules and associated with exposure to the common allergen, house dust mite (HDM), and the development of AHR through epigenetic modulation of the airway smooth muscle (ASM) cell phenotypes. In addition, we identified a novel role of the specific 5-mC dioxygenase, TET1, in the regulation of ASM function in vitro and in the development of allergen-driven AHR in vivo. Preliminarily, we demonstrated Tet1 deficiency reduced acute HDM-driven AHR in mice. Strikingly, we were able to translate the epigenetic changes in human asthmatic ASM cells; showing Tet1-mediated hydroxymethylation may influence ASM cell proliferation and contraction. Our study represents the first demonstration that Tet1 protein is regulated in the context of allergen exposure, although the mechanisms regulating Tet1 induction by allergens are unknown. Our preliminary data supported that oxidative stress generated by HDM exposure activates Tet1 and its mediated upregulation of ASM genes. Based on these novel findings, we propose the central hypothesis "HDM activates Tet1-mediated hydroxymethylation in ASM cells through regulation of redox cycling. This epigenetic reprogramming persists in ASM over long time spans, thus likely contributes to the increased ASM cell proliferation, stiffness and contractility seen in human asthma". To address these novel hypotheses, we have assembled a multi-disciplinary team of investigators with a breadth of expertise spanning the fields of epigenetics, ASM biology, pulmonology and pathobiology. First, we will determine the role of Tet1- mediated DNA hydroxymethylation in the development of the AHR phenotype in a chronic HDM-induced AHR mouse model. Second, we will investigate how HDM alters the Tet1 activity, through redox cycling of NADH in both in vitro and in vivo mouse model. Lastly, we will confirm if TET1-mediated hydroxymethylation regulates human ASM cell phenotypes. The results of the proposed experiments should provide novel perspectives on the ASM and its contributions to the excessive airway narrowing in asthma. These insights may fuel the development of new therapeutic approaches for the treatment of this debilitating disease.