Posttranscriptional Gene Regulation in Asthma

描述(申请人提供)：由于不明原因，哮喘的患病率和严重程度一直在增加。虽然我们对哮喘的病理生理机制的了解仍然很少，但人们普遍认为哮喘是一种炎症性疾病，而分泌Th2细胞因子的CD4+T细胞被认为是其发展的主要罪魁祸首。这些基因中有许多是转录后调控的，但它们的调控还不是很清楚。目前的方法强调使用微阵列来定义“哮喘特征基因”。尽管这些方法是有帮助的，但它们也是不完整的，可能会遗漏重要的靶基因，因为稳定状态的mRNA水平和蛋白质生产之间的相关性很差。我们发展了一种新的范式，即转录后操纵子假说，该假说认为RNA结合蛋白正在协调调节生物相关分子的表达，例如那些参与T细胞激活的分子。我们的中心假设是，RNA结合蛋白HUR在过敏原驱动的哮喘中协调调节IL-4和IL-13细胞因子基因。RNA结合蛋白Hur与mRNAs 3‘非翻译区的富含AU元件(ARE)结合，调节其稳定性和翻译。ARE基序存在于8%的人类基因中，在转录后基因表达中起着关键作用。尤其是两种主要的Th2细胞因子，IL-4和IL-13，被认为在变应原驱动的哮喘中起关键作用，受Hur在mRNA稳定和翻译水平上的调节。我们已经开发了新的方法来识别体内整体细胞Hur mRNA靶标。利用这些方法，我们已确定IL-4和IL-13为HUR靶标。我们将通过以下两个具体目标来检验这一假说：1：检测CD4+T细胞HUR调节对IL-4和IL-13表达的影响。2：评价HUR在哮喘小鼠模型中的作用。我们的方法将更全面地了解致炎细胞因子基因在过敏原驱动的哮喘中的调节作用。在转录后水平上更好地了解促炎基因调控可能会导致有针对性的治疗哮喘。公共卫生相关性：世界各地过敏症和哮喘的增加继续困扰着医生和科学家。这一增长的原因尚不清楚。对哮喘治疗的不同反应很可能是由于患者的遗传背景不同所致。在转录后基因调控水平上更好地了解哮喘的病理生理学，将大大有助于我们对疾病发病机制和治疗的理解，并对公众健康有直接影响。

DESCRIPTION (provided by applicant): Asthma has been increasing in prevalence and severity for unknown reasons. Though our understanding of the pathophysiology remains poor, it is widely accepted that asthma is an inflammatory disease and CD4+ T cells elaborating Th2 cytokines have been identified as major culprits in its development. Many of these genes are posttranscriptionally regulated but their regulation is not well understood. Current approaches have emphasized the use of microarrays to define "asthma signature genes". Though these approaches are helpful, they are also incomplete and may miss important target genes since there is a poor correlation between steady-state mRNA levels and protein production. We have developed a new paradigm, the posttranscriptional operon hypothesis, which states that RNA binding proteins are coordinately regulating the expression of biologically related molecules, such as those involved in T cell activation. Our central hypothesis is that the RNA binding protein, HuR, is coordinately regulating IL-4 and IL-13 cytokine genes during allergen driven asthma. The RNA binding protein, HuR, binds to the AU-rich elements (ARE) in the 3' untranslated regions (UTR) of mRNAs and modulates their stability and translation. The ARE motif is found in 8% of human genes and plays a critical role in posttranscriptional gene expression. In particular, two major Th2 cytokines, IL- 4 and IL-13, believed to play critical roles in allergen driven asthma, are regulated by HuR at the level of mRNA stability and translation. We have developed novel methods to identify en masse cellular in vivo HuR mRNA targets. Using these approaches, we have identified IL-4 and IL-13 as HuR targets. We will test this hypothesis with the following two specific aims: 1: Examine the effects of HuR modulation in CD4+ T cells upon IL-4 and IL-13 expression. 2: Assess the role of HuR in CD4+ T cells in allergen driven models of asthma in mice. Our approach will provide a fuller understanding of the regulation of proinflammatory cytokine genes involved in allergen driven asthma. Better understanding of proinflammatory gene regulation at posttranscriptional level may potentially lead to targeted therapies to treat asthma. Public Health Relevance: The rise of allergies and asthma around the world continues to perplex physicians and scientists. The reasons for this increase are unknown. Different responses to therapies for asthma are most likely due to differences in genetic backgrounds of patients. A better understanding of asthma pathophysiology at the posttranscriptional gene regulation level would greatly aid in our understanding of disease pathogenesis and treatment and have a direct impact on public health.