Role of the ER stress transcription factor XBP1S in the development of idiopathic pulmonary fibrosis

ER应激转录因子XBP1S在特发性肺纤维化发展中的作用

• 批准号: 10318142
• 负责人: Gang Chen
• 金额: $ 41.72万
• 依托单位: UNIV OF NORTH CAROLINA CHAPEL HILL
• 依托单位国家: 美国
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-12-15 至 2025-11-30
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10318142
• 关键词: 3-Dimensional; Affect; Aging; Alleles; Alveolus; Apoptosis; Binding; Binding Proteins; Biochemical; Biological Assay; Bleomycin; Cells; Cellular Stress; Cyst; Data; Defect; Development; Disease Progression; Distal; Early Diagnosis; Electrophysiology (science); Environmental Risk Factor; Epithelial; Epithelial Cells; Etiology; Exposure to; Factor X; Fibroblasts; Fibrosis; Functional disorder; Gene Expression; Genes; Genetic; Host Defense; Human; Hypoxia; Impairment; In Vitro; Individual; Infection; Influenza; Influenza A Virus, H1N1 Subtype; Injury; Laboratories; Lead; Lung; Lung diseases; MUC5B gene; Maintenance; Mediating; Messenger RNA; Minor; Modeling; Mucins; Mucociliary Clearance; Mucous body substance; Mus; Mutation; Myofibroblast; Natural regeneration; Onset of illness; Peripheral; Persons; Phenotype; Predisposition; Production; Proteins; Pulmonary Fibrosis; RNA Splicing; Risk; Risk Factors; Role; System; Telomerase; Testing; Time; Variant; XBP1 gene; airway epithelium; airway remodeling; alveolar epithelium; alveolar type II cell; biophysical properties; effective therapy; endoplasmic reticulum stress; epithelial injury; genetic variant; idiopathic pulmonary fibrosis; in vitro Assay; in vivo; injury and repair; lung repair; mouse genetics; mouse model; notch protein; novel; novel marker; overexpression; prevent; progenitor; promoter; repaired; response; response to injury; stem cell function; stem cell homeostasis; stem cells; surfactant; therapeutic target; transcription factor

Idiopathic pulmonary fibrosis (IPF) is a progressive and end-stage lung disease of unknown etiology and no cure. It is likely that genetic changes increase a person's risk of developing IPF, and then exposure to certain environmental factors and/or aging trigger the onset of the disease. The MUC5B promoter variant rs35705950 is present in ∼50% of individuals with IPF and is recognized as the strongest known risk factor (genetic and otherwise) for the development of IPF. This variant leads to overexpression of MUC5B mRNA and protein in both distal airway epithelia and honeycomb cysts in the peripheral lung. These observations raise the question of why excessive MUC5B expression in distal airways is associated with IPF? Recently, our laboratory identified for the first time that the ER stress transcription factor XBP1S is highly expressed in the epithelium lining the distal airways and honeycomb cysts of IPF lung, activates MUC5B gene expression by direct binding to its promoter. Further, XBP1S differentially regulating the MUC5B promoter variant. These data connected activation of ER stress with excessive MUC5B expression in a promoter variant-dependent model likely impairs mucociliary clearance and function of distal airway stem cells that increase susceptibility of development of pulmonary fibrosis. We hypothesize that activation of XBP1S induces MUC5B expression in the distal airways that promotes pulmonary fibrosis. To test this central hypothesis, we propose the following aims: 1) XBP1S- mediated MUC5B secretion in distal airway epithelium enhances susceptibility to development of pulmonary fibrosis in vivo. We will assess the role of XBP1S by exposing Xbp1 airway epithelium-specific overexpression or deletion mice to bleomycin induced respiratory epithelial injury. 2) XBP1S-mediated MUC5B secretion impairs distal airway stem cell function to repair peripheral lung epithelia after injury. We will utilize mouse airway epithelium-lineage tracing system and in vitro 2-D and 3-D differentiation assays to evaluate the role of XBP1S and mucin in maintenance of the airway stem cell homeostasis in response to injury. 3) Activation of XBP1S and presence of MUC5B promoter variant cause abnormal mucus secretion, impaired mucociliary clearance and activation of myofibroblast differentiation. We will analyze the biochemical and biophysical properties of the secreted mucus and electrophysiology of the DAE carrying the MUC5B promoter variant rs35705950 at baseline and after activation of ER stress. We will also test whether XBP1S-expressing DAE carrying the MUC5B promoter variant and/or hypoxia-induced epithelial injury directly promotes myofibroblast differentiation. Completing the aims proposed in this application will provide novel mechanisms underlying ER stress-mediated excessive mucin secretion by DAE promotes pulmonary fibrosis. These mechanistic studies will likely identify novel biomarkers for early diagnosis as well as therapeutic targets (e.g., suppression of XBP1S activation as a promising approach to resolve MUC5B hypersecretion, even for those carrying the MUC5B promoter variant) in the distal lung to prevent or reverse fibrotic disease progression.

特发性肺纤维化（IPF）是一种进展性的终末期肺病，病因学和 无法治愈。遗传变化可能会增加一个人发展IPF的风险，然后暴露于某些 环境因素和/或衰老会触发疾病的发作。 MUC5B启动子变体RS35705950 存在于约50％的IPF患者中，被认为是强烈的已知危险因素（遗传和 否则）用于开发IPF。这种变体导致MUC5B mRNA和蛋白质中的过表达 远端气道上皮和外周肺中的蜂窝囊肿。这些观察提出了一个问题 为什么远端气道中超过的MUC5B表达与IPF相关？最近，我们的实验室确定了 ER应力转录因子XBP1首次在上皮衬里高度表达 IPF肺的远端气道和蜂窝状囊肿，通过直接结合与其激活MUC5B基因表达 发起人。此外，XBP1对MUC5B启动子变体的调节不同。这些数据连接激活 在启动子变异依赖性模型中具有过量MUC5B表达的ER应力可能会损害粘膜纤毛 远端气道干细胞的清除和功能增加了肺发育易感性 纤维化。我们假设XBP1的激活会影响远端气道中的MUC5B表达 促进肺纤维化。为了检验该中心假设，我们提出以下目的：1）XBP1S- 远端气道上皮的介导的MUC5B分泌增强了对发展的敏感性 体内肺纤维化。我们将通过暴露XBP1气道上皮特异性来评估XBP1的作用 过表达或缺失小鼠至博来霉素诱导呼吸性上皮损伤。 2）XBP1S介导的MUC5B 分泌会损害远端气道干细胞功能，以修复受伤后的周围肺上皮。我们将 利用鼠标气道上皮linege跟踪系统和体外2-D和3-D分化测定法进行评估 XBP1和粘蛋白在维持气道干细胞体内稳态中的作用在响应损伤的情况下。 3） XBP1的激活和MUC5B启动子变体的存在引起异常粘液分泌， 粘膜缩减清除率受损和肌纤维细胞分化的激活。我们将分析 分泌的粘液的生化和生物物理特性以及携带的DAE的电生理学 MUC5B启动子变体RS35705950在基线和激活ER应力后。我们还将测试是否 携带MUC5B启动子变体和/或缺氧诱导的上皮损伤的表达DAE直接 促进肌纤维细胞分化。完成本申请中提出的目标将提供新颖 ER应力介导的DAE的过量粘蛋白分泌的机制促进了肺纤维化。 这些机械研究可能会确定早期诊断和治疗靶标的新型生物标志物 （例如，抑制XBP1S激活是解决MUC5B超验的有前途的方法，即使 携带MUC5B启动子变体的患者在远端肺中以预防或逆转纤维化疾病进展。