HuR in Allergic Asthma and T Cell Differentiation

描述（由申请人提供）：由于未知的原因，过敏和哮喘的发病率在美国持续增加。越来越清楚的是，哮喘是一种异质性疾病，具有不同的内型，这表明不同的病理生理。在人类中，哮喘有过敏性和非过敏性两种形式。这是一个未满足的需要，在该领域更好地了解哪些不同的机制有助于哮喘内型。基因组宽阵列分析已经鉴定出许多哮喘相关基因。然而，由于稳态mRNA水平与蛋白质之间的相关性较差，转录组学方法可能会忽略关键基因。RNA结合蛋白（rbp）和microRNAs （miRNAs）的转录后基因调控越来越被认为是促炎基因的重要调控机制。rbp，如与富au元素（AREs）结合的HuR (elav1)，通过稳定靶基因mrna和增加可翻译性，在协调调节哮喘促炎基因中发挥关键作用。我们实验室和其他实验室使用的方法，称为应用于微阵列的RNA免疫沉淀（RIP-Chip），已经确定了rbp是如何协调调节炎症的。转录后基因调控在CD4+ T分化中起重要作用，但这些过程尚不清楚。我们的长期目标是了解气道炎症的转录后基因调控。该应用程序的目标是了解HuR如何在过敏原挑战期间调节关键分子，如Th2/Th17细胞因子和IL-2，这是我们追求这一目标的下一步。中心观点是RBP，即HuR，允许CD4+ Th2介导的过敏性气道炎症的发展，并且是正常IL-2稳态表达所必需的。这一建议的基本原理是，我们的工作已经证明HuR控制Th2和Th17分化。由于抑制Th2细胞因子的产生，HuR KO小鼠不会发生气道炎症，并且在T细胞激活后不具有关闭IL-2表达的能力。了解IL-2和Th2/Th17细胞因子基因调控的转录后机制将使该领域能够调节和影响过敏原驱动哮喘炎症反应的结果，也可能有助于更好地定义哮喘内型之间的异质性。我们计划通过以下四个具体目标来测试中心esis并实现这些目标：1)HuR消融是否改变CD4+ Th亚群分化？2)确定体内变应性气道炎症是否需要HuR；3) IL-2和Th2细胞因子表达的机制决定因素；4)确定人淋巴细胞是否存在HuR表达异常。我们相信我们的研究是创新的，因为这些方法将为T细胞转录后细胞因子调节提供新的机制见解。这项研究具有重要意义，因为它将阐明气道反应如何在分子水平上与适应性免疫和先天免疫联系起来，以控制肺部炎症。

DESCRIPTION (provided by applicant): For unknown reasons, the incidence of allergies and asthma continues to increase in the US. It is increasingly clear that asthma is a heterogeneous disease with differing endotypes which suggest discrete pathophysiology. In humans, asthma exists in allergic and non-allergic forms. It is an unmet need in the field to better understand ho different mechanisms contribute to asthma endotypes. Genome wide array analysis has identified many asthma relevant genes. However, due to poor correlation between steady state mRNA levels and protein, transcriptomic approaches may overlook critical genes. Posttranscriptional gene regulation by RNA binding proteins (RBPs) and microRNAs (miRNAs) are increasingly recognized as important control mechanisms for proinflammatory genes. RBPs, such as HuR (elav1) which bind to AU-rich elements (AREs) play critical roles in coordinately regulating proinflammatory genes in asthma by stabilizing target gene mRNAs and increasing translatability. Methods used by our lab and others, called RNA immunoprecipitation applied to microarrays (RIP-Chip) have identified how RBPs are coordinately regulating inflammation. Posttranscriptional gene regulation plays an important role in CD4+ T differentiation, yet these processes are poorly understood. Our long term goal is to understand posttranscriptional gene regulation in airway inflammation. The objective of this application, which is our next step in pursuit of that goal, is to understand how HuR is regulating key molecules, such as Th2/Th17 cytokines and IL-2 during allergen challenge. The central esis is that the RBP, HuR, is permissive for development of CD4+ Th2 mediated allergic airway inflammation and required for normal IL-2 homeostatic expression. The rationale for this proposal is that our work has demonstrated that HuR controls both Th2 and Th17 differentiation. HuR KO mice do not develop airway inflammation due to suppression of Th2 cytokine production and do not have the ability to turn off IL-2 expression following T cell activation. Understanding posttranscriptional mechanisms of IL-2 and Th2/Th17 cytokine gene regulation will allow the field to modulate and affect outcomes of inflammatory responses in allergen driven asthma and also perhaps aid in better defining the heterogeneity amongst asthma endotypes. We plan to test the central esis and accomplish these objectives by the following four specific aims: 1) Does HuR ablation alter CD4+ Th subset differentiation?; 2) Determine whether HuR is required for allergic airway inflammation in vivo; 3) Mechanistic determinants of IL-2 and Th2 cytokine expression; 4) Determine whether human lymphocytes have dysregulated HuR expression. We believe our study is innovative, because such approaches will provide novel mechanistic insights into T cell posttranscriptional cytokine regulation. The proposed research is significant, because it will elucidate how airway responses connect at the molecular level with both adaptive and innate immunity to control lung inflammation.