Genes and Transcripts that Interact with MUC5B in Pulmonary Fibrosis

摘要 我们提出的研究的总体目标是确定与MUC5B相关的基因和转录本 参与特发性肺纤维化(IPF)发展的基因表达。罕见突变(16- 21)和常见的变异(22-26)与特发性肺纤维化有关，至少占发病风险的40% 这种病。在过去的5年中，我们发现：1)一个功能增强的MUC5B启动子突变体rs35705950 是IPF发展的最强危险因素(22，26-34)；2)表观遗传机制影响IPF MUC5B(35)的表达；3)IPF是一种复杂的遗传病，具有罕见和常见的变异，导致 这种疾病的发展，包括DNA甲基化的显著变化(36)和转录 亚型(37)；4)MUC5B似乎与IPF的发病有关(27，38-40)。然而，还有 MUC5B启动子变异外显率低的原因尚不清楚，而MUC5B的次要等位基因是 在≈人群中，19%的人处于杂合或纯合子状态(27)，发生特发性肺纤维化的几率要低得多。 不到1%的人口(41，42)。这些观察结果使我们假设，IPF的病因最好是 通过识别控制MUC5B表达的基因和转录本来理解 肺纤维化的发展。为了产生一个可行的实验模型来追求这一概念，我们 8个方正小鼠品系对气管内注射博莱霉素的反应 该多样性杂交(DO)小鼠种群(43只)并发现，尽管在 MUC5B RNA和MUC5B蛋白表达与博莱霉素性肺纤维化的关系 始终如一的八大方正做老鼠品系。这些初步发现表明，DO小鼠 种群可用于将遗传变异与基因表达相结合，以创建多尺度模型 博莱霉素诱导的肺纤维化，并利用这一知识了解MUC5B诱导的遗传基础 IPF。基于这些观察，我们假设控制博莱霉素的基因和转录本- 诱导MUC5B/MUC5B表达增加了发生肺纤维化的风险。在这个项目中， 我们计划对900只DO小鼠进行表型和基因分型，以确定它们对博莱霉素的反应 控制MUC5B蛋白表达并促进肺纤维化的发展(目标1)，同时还 鉴定与博莱霉素性肺纤维化相关的转录变化(包括MUC5B转录本) (目标2)。然后我们将确定这些候选基因和在小鼠身上发现的转录变化 暴露于博莱霉素者可推广为IPF(目标3)。这些目标的成功实现将具有广泛的意义。 影响，导致特定的遗传靶点和生物途径用于未来预防措施的设计， IPF的机理和干预研究。

ABSTRACT The overall goal of our proposed research is to identify genes and transcripts associated with MUC5B expression that contribute to the development of idiopathic pulmonary fibrosis (IPF). Rare mutations (16- 21) and common variants (22-26) are associated with IPF and account for at least 40% of the risk of developing this disease. In the past 5 years, we have found that: 1) a gain-of-function MUC5B promoter variant rs35705950 is the strongest risk factor for the development of IPF (22, 26-34); 2) epigenetic mechanisms affect the expression of MUC5B (35); 3) IPF is a complex genetic disease with rare and common variants contributing to the development of this disease, including pronounced changes in DNA methylation (36) and transcriptional subtypes (37); and 4) MUC5B appears to be involved in the pathogenesis of IPF (27, 38-40). However, there is no clear explanation for the low penetrance of the MUC5B promoter variant; while the minor allele of MUC5B is present in the heterozygous or homozygous state in ≈19% of the general population (27), IPF occurs in far less than 1% of the population (41, 42). These observations lead us to postulate that the etiology of IPF will best be understood by identifying the genes and transcripts that control MUC5B expression and contribute to the development of pulmonary fibrosis. To generate a feasible experimental model to pursue this concept, we phenotyped the response to intratracheal bleomycin in the eight founder mouse strains that were used to create the Diversity Outbred (DO) mouse population (43) and found that although there is a clear relationship between Muc5b RNA and MUC5B protein expression and bleomycin-induced lung fibrosis, this relationship is not consistent across the eight founder DO mouse strains. These preliminary findings suggest that the DO mouse population can be used to integrate genetic variation with gene expression to create multi-scale models of bleomycin-induced lung fibrosis and then use this knowledge to understand the genetic basis of MUC5B-induced IPF. Based on these observations, we hypothesize that genes and transcripts that control bleomycin- induced Muc5b/MUC5B expression contribute to the risk of developing pulmonary fibrosis. In this project, we plan to phenotype and genotype 900 DO mice for their response to bleomycin to identify the genes that control MUC5B protein expression and contribute to the development of lung fibrosis (Aim 1), while also identifying transcriptional changes (including Muc5b transcript) associated with bleomycin-induced lung fibrosis (Aim 2). We will then determine whether these candidate genes and transcriptional changes identified in mice exposed to bleomycin are generalizable to IPF (Aim 3). The successful completion of these Aims will have broad impact, resulting in specific genetic targets and biologic pathways for use in the design of future preventive, mechanistic, and intervention studies of IPF.