Mitochondrial-epigenetic crosstalk in regulation of airway hyperresponsiveness

项目摘要 哮喘是一种以气道高反应性（AHR）为特征的复杂疾病， 到2025年全球将有4亿人。气道平滑肌（ASM）细胞是AHR的主要效应细胞， 它们夸大了对支气管收缩刺激的反应，并通过沉积 细胞外基质和诱导炎症。靶向表观遗传变化是一种新的方法， 逆转哮喘患者中异常的ASM表型。我们之前证明了全球DNA α-酮戊二酸（αKG）依赖的5-mC双加氧酶（TET 1）介导的羟甲基化在 小鼠的肺组织显示过敏原诱导的AHR增加。此外，我们报告了一个新的作用， 肾脏特异性异柠檬酸脱氢酶2（IDH 2）对人ASM表型基因的调控 哮喘ASM细胞，通过改变αKG水平和α KG依赖的TET 1活性，提示可能的 细胞代谢和ASM细胞功能的表观遗传调节之间的联系。准确地说，过敏原- 诱导的AHR和异常的DNA羟甲基化模式被一种靶向的 四肽，SS-31（依拉普利肽，目前处于治疗代谢性疾病的III期临床试验中）。 此外，我们发现线粒体和表观基因组之间的相互作用是双向的。我们 鉴定了参与线粒体复制和转录的基因的DNA羟甲基化增加， 这与AHR增加有关。我们的研究首次证明TET 1- ASM中介导的DNA羟甲基化在线粒体功能的背景下受到调节， 线粒体功能影响ASM细胞功能的表观遗传调节的机制，以及 反之亦然;没有得到充分调查。基于这些新的发现，我们提出了中心假设 “线粒体氧化还原循环和生物能量学的调节与表观遗传修饰相互作用， ASM细胞功能，并最终改变哮喘发病机制”。为了解决这些新的假设，我们 组建一支具有广泛专业知识的研究团队，涵盖表观遗传学，氧化还原生物学 肺科。首先，我们将确定线粒体功能的调节是否具有表观遗传学上的作用。 对过敏原诱导的AHR的影响，可通过SS-31减弱。其次，我们将研究表观遗传是否 线粒体转录的调节调节线粒体的功能，这对线粒体的功能有长期的影响。 ASM细胞的表观基因组和AHR表型。最后，我们将确认 在利用临床样品测定ASM功能中的相互作用。我们将应用相关性分析， 线粒体生物学的基因组分析和测量，以鉴定与线粒体生物学相关的分子标记物组。 哮喘的严重程度。我们的研究结果应该提供新的证据， ASM细胞和AHR相互作用的结果。这些见解可能会推动新的 用于治疗这种使人衰弱的疾病的治疗方法。

Project Summary Asthma is a complex disease characterized by airway hyperresponsiveness (AHR), which is expected to affect 400 million people worldwide by 2025. Airway smooth muscle (ASM) cells are the primary effectors of AHR, as they exaggerate the response to bronchoconstrictor stimuli and increase ASM thickness by depositing the extracellular matrix and inducing inflammation. Targeting epigenetic changes serves as a new approach to reversing the aberrant ASM phenotypes seen in asthmatics. We previously demonstrated that global DNA hydroxymethylation mediated by α-ketoglutarate (αKG)-dependent 5-mC dioxygenase (TET1) was induced in lung tissues from mice that showed increased allergen-induced AHR. In addition, we reported a novel role for mitochondrial-specific isocitrate dehydrogenase 2 (IDH2) on regulation of ASM phenotypic genes in human asthmatic ASM cells, through alterations in αKG level and αKG-dependent TET1 activity, suggesting a possible link between cell metabolism and epigenetic regulation of ASM cell function. Preliminarily, the allergen- induced AHR and aberrant DNA hydroxymethylation patterns was abolished by a mitochondrially targeted tetrapeptide, SS-31(elamipretide, which is currently in phase III clinical trials for treating metabolic diseases). Furthermore, we showed that the interaction between mitochondria and epigenome is bidirectional. We identified increased DNA hydroxymethylation of genes involved in mitochondrial replication and transcription, which was associated with the increased AHR. Our study represents the first demonstration that TET1- mediated DNA hydroxymethylation in ASM is regulated in the context of mitochondrial function, although the mechanisms by which mitochondrial function influences the epigenetic regulation of ASM cell function, and vice versa; have not been fully investigated. Based on these novel findings, we propose the central hypothesis “Modulation of mitochondrial redox cycling and bioenergetics reciprocates with the epigenetic modifications of the ASM cell function, and ultimately modifying asthma pathogenesis”. To address these novel hypotheses, we assemble a team of investigators with a breadth of expertise spanning the fields of epigenetics, redox biology and pulmonology. First, we will determine whether modulation of mitochondrial function has an epigenetic impact on allergen-induced AHR, which can be attenuated by SS-31. Second, we will study if epigenetic regulation of mitochondrial transcription modulates mitochondrial function, which has a long-term effect on the epigenome of the ASM cells and AHR phenotype. Finally, we will confirm the mitochondrial-epigenetic interplays in the determination of ASM function utilizing clinical samples. We will apply correlation analysis of genomic profiling and measurement of mitochondrial biology to identify sets of molecular markers associated with asthma severity. Our findings should provide new evidence about the mitochondrial-epigenetic crosstalk in ASM cells and the results of that interaction on AHR. These insights may fuel the development of new therapeutic approaches for the treatment of this debilitating disease.