Genetics and Gene Expression Profiling in Asthma

描述(申请人提供)：哮喘是最常见的慢性呼吸性肺部疾病，在美国有1700多万人受到影响；识别其分子决定因素仍然是翻译科学的重要优先事项。四年前，我们提出了一种整合的基因组方法，将全基因组的遗传和表达研究(所谓的表达数量性状基因座(EQTL)定位)结合起来，以便于识别与哮喘发病机制和自然历史有关的新的调节性遗传变异。利用这种方法，我们在四个不同的基因组区域发现了与哮喘易感性有关的新的调节基因变异：染色体17q基因座(包括基因ZPBP2、GSDMB和ORMDL3)；脂肪酸去饱和酶基因座(FADS1和FADS2)；N-乙酰半乳糖胺酶(NAGA)基因座和因子XIIIA亚单位(F13A1)基因座。我们现在建议扩展这些研究的目标是：(1)定位有助于哮喘发病机制的其他调控变量；(2)识别与哮喘遗传关联的特定功能调控变量；以及(3)表征这些候选基因在哮喘发生发展中的功能作用。在具体目标1中，我们将通过使用来自4,000多个不同祖先的对象的四个大型现有数据集的数据进行第一次eQTL荟萃分析，从而扩展我们在整合基因组学方面的先前工作。这一努力的结果将被用于重新解释哮喘全基因组关联研究的荟萃分析。相关关系将在另外三个哮喘队列中复制(n E12,000)。在特定的目标2中，我们将通过等位基因不平衡筛选、基于染色质的DNA-DNA和DNA-蛋白质相互作用研究以及等位基因特异性报告分析，对三个新的哮喘基因座(FADS2、NAGA和F13A1)在人支气管上皮细胞及其相关细胞类型中进行功能精细定位。已确认的功能变异将在Eve Consortium队列中测试与哮喘的遗传关联。在具体目标3中，我们将在已建立的小鼠模型中对FADS2基因进行功能评估，并使用体外细胞分析证实FADS2基因在小鼠和人类来源的人支气管上皮细胞中的分子机制。该项目有可能精确定位参与哮喘发病机制的功能性基因变异，并提供更好的了解这些基因在哮喘发病机制中的作用，从而为旨在改变其异常基因表达的新药开发奠定坚实的基础。 公共卫生相关性：哮喘是最常见的慢性呼吸系统肺部疾病；识别其分子决定因素仍然是翻译科学的重要优先事项。通过这一应用确定的哮喘相关调节基因变异将为哮喘的发病机制提供新的见解。FADS2的研究将证实它是通过改变脂肪酸摄入量的饮食来进行治疗开发或环境改良的潜在靶点。

DESCRIPTION (provided by applicant): Asthma is the most common chronic respiratory lung disease, affecting more than 17 million people in the US; identification of its molecular determinants remains an important priority in translational science. Four years ago, we proposed an integrative genomic approach that combined genome-wide genetic and expression studies (so-called expression quantitative trait locus (eQTL) mapping) to facilitate the identification of novel regulatory genetic variation contributing to the pathogenesis and natural history of asthma. Using this approach, we identified novel regulatory genetic variants that confer susceptibility to asthma at four distinct genomic regions: the chromosome 17q locus (that includes the genes ZPBP2, GSDMB and ORMDL3); the Fatty Acid Desaturase locus (FADS1 & FADS2); the N-acetyl galactosaminidase (NAGA) locus, and the factor XIII A subunit (F13A1) locus. We now propose to extend these studies with the goals of (1) mapping additional regulatory variants that contribute to the pathogenesis of asthma; (2) identifying the specific functional regulatory variants underlying the genetic associations with asthma; and (3) characterizing the functional role of these candidate genes in the development of asthma. In Specific Aim 1 we will extend our previous work in the integrative genomics by performing a first of its kind eQTL meta-analysis using data from four large existing datasets of more than 4,000 subjects of diverse ancestry. Results from this effort will be used to reinterpret a meta-analysis of asthma genome-wide association studies. Associations will be replicated in three additional asthma cohorts (n E12,000). In Specific Aim 2, we will perform functional fine-mapping of three of the novel asthma loci (FADS2, NAGA and F13A1) in human bronchial epithelial cells and related cell types by means of allelic imbalance screens, chromatin-based DNA-DNA and DNA-protein interaction studies, and allele specific reporter assays. Confirmed functional variants will be tested for genetic association with asthma in the EVE Consortium cohorts. In Specific Aim 3, we will conduct a functional evaluation of the FADS2 gene in an established murine model, with confirmation of the molecular mechanisms using in vitro cellular assays in both murine- and human-derived human bronchial epithelial cells. This project has high potential to precisely localize functional genetic variants contributing to the pathogenesis of asthma, and provide a better understanding of the role of these genes in the pathogenesis of asthma, thereby establishing a solid foundation for new drug development aimed at modifying their aberrant gene expression. PUBLIC HEALTH RELEVANCE: Asthma is the most common chronic respiratory lung disease; identification of its molecular determinants remains an important priority in translational science. The asthma-associated regulatory genetic variants identified through this application will provide novel insights into the pathogenesis of asthma. The studies of FADS2 will confirm it as a potential target for therapeutic development or environmental modification through dietary modification of fatty acid intake.