Epithelial abnormalities in IPF: role of ER stress and GRP78/BiP

IPF 中的上皮异常：ER 应激和 GRP78/BiP 的作用

• 批准号: 8577607
• 负责人: Beiyun Zhou
• 金额: $ 39.03万
• 依托单位: UNIVERSITY OF SOUTHERN CALIFORNIA
• 依托单位国家: 美国
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-08-01 至 2018-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8577607
• 关键词: Acetylcysteine; Address; Alveolar; Antioxidants; Apoptosis; Binding; Bone Marrow; Cell Line; Cells; Cicatrix; Data; Deposition; Disease; Dose; Endoplasmic Reticulum; Environment; Epithelial; Epithelial Cells; Epithelium; Etiology; Extracellular Matrix; Fibroblasts; Fibrosis; Functional disorder; Generations; Goals; Hamman-Rich syndrome; Homeostasis; In Vitro; Injury; Interstitial Lung Diseases; Knock-out; Knockout Mice; Lead; Link; Lung; Lung diseases; Mediating; Mediator of activation protein; Membrane; Mesenchymal; Modeling; Molecular; Molecular Chaperones; Mus; Mutation; Myofibroblast; Oxidative Stress; Pathogenesis; Pathway interactions; Phenotype; Play; Predisposition; Process; Proteins; Pulmonary Fibrosis; Pulmonary Surfactant-Associated Protein C; Reactive Oxygen Species; Reporting; Respiratory physiology; Role; Signal Transduction; Tissues; Wound Healing; age related; alveolar epithelium; biological adaptation to stress; cell injury; clinically relevant; effective therapy; endoplasmic reticulum stress; fibrogenesis; glucose-regulated proteins; in vivo; inhibitor/antagonist; injured; insight; monolayer; mutant; new therapeutic target; novel; overexpression; pneumocyte; prevent; protein degradation; protein folding; protein misfolding; public health relevance; response; sensor; src-Family Kinases; surfactant; treatment strategy

DESCRIPTION (provided by applicant): Idiopathic pulmonary fibrosis/usual interstitial pneumonia (IPF/UIP) is a devastating interstitial lung disease of unknown etiology, characterized by (myo)fibroblast activation/proliferation, extracellular matrix (ECM) deposition and progressive lung destruction. A central role for alveolar epithelium in IPF/UIP pathogenesis has recently been postulated. In this paradigm, injured alveolar epithelial cells (AEC) actively participate in fibrogenesis by releasing fibroproliferative mediators that promote proliferation an differentiation of fibroblasts that in turn induce AEC apoptosis and/or giving rise directly to fibroblasts through epithelial-mesenchymal transition (EMT). However, mechanisms underlying AEC injury/activation and downstream molecular pathways linking epithelial abnormalities to fibrosis remain unclear. Association between endoplasmic reticulum (ER) stress and both sporadic and familial pulmonary fibrosis associated with surfactant protein (SP) mutations has been reported. We recently found that ER stress triggers protective signaling known as the unfolded protein response (UPR) and induces both apoptosis and EMT in AEC in vitro via activation of the non-receptor membrane-associated tyrosine kinase Src, supporting a causal role for ER stress in the dysfunctional AEC phenotype in pulmonary fibrosis. Preliminary data suggest that reactive oxygen species (ROS) and b-catenin activation/interaction with the co-activator CBP are involved in Src-dependent signaling. The ER chaperone glucose-regulated protein 78 (GRP78) is a master regulator of ER homeostasis and thus represents an ideal target with which to modulate ER stress responses in alveolar epithelium. The overall goals of this proposal are to investigate mechanisms underlying ER stress-induced epithelial abnormalities implicated in the pathogenesis of fibrosis by modulating GRP78 utilizing mice with lung epithelial cell-specific deletion of Grp78. We hypothesize that (1) loss of Grp78 induces and/or exacerbates experimental fibrosis in vivo; (2) GRP78 insufficiency-induced epithelial injury contributes to fibrosis via direct effects on the epithelium (e.g., apoptosis/EMT) and/or abnormal epithelial-fibroblast crosstalk; and, (3) effects of GRP78 insufficiency on EMT/fibrosis are mediated via Src and/or ROS-dependent ¿-catenin/CBP signaling. We will use AEC-specific Grp78 knockout mice, in conjunction with clinically relevant mutant SP-C¿exon4, our well- established primary AEC in vitro monolayer model, and ICG-001, a novel inhibitor of ¿-catenin/CBP interaction, to address the following Specific Aims: 1. Evaluate effects of ER stress mediated by loss of Grp78 on pulmonary fibrosis in inducible AEC-specific Grp78 knockout mice; 2. Investigate the role of ER stress in AEC abnormalities (apoptosis vs EMT vs aberrant epithelial-fibroblast crosstalk) implicated in fibrosis in inducible AEC-specific Grp78 knockout mice; and 3. Determine mechanisms underlying ER stress-induced AEC injury/fibrosis. These studies will provide insights into mechanisms underlying the pathogenesis of IPF and facilitate identification of novel therapeutic targets for this incurable disease.

描述(申请人提供)：特发性肺纤维化/普通性间质性肺炎(IPF/UIP)是一种原因不明的破坏性间质性肺疾病，以(Myo)成纤维细胞激活/增殖、细胞外基质(ECM)沉积和进行性肺破坏为特征。肺泡上皮细胞在IPF/UIP发病机制中的中心作用最近被推测。在这种模式下，受损的肺泡上皮细胞(AEC)通过释放纤维增殖介质，促进成纤维细胞的增殖和分化，进而诱导AEC凋亡和/或通过上皮-间充质转化(EMT)直接形成成纤维细胞，从而积极参与纤维化的形成。然而，AEC损伤/激活的机制以及将上皮异常与纤维化联系起来的下游分子通路仍不清楚。内质网(ER)应激与肺表面活性蛋白(SP)突变相关的散发性和家族性肺纤维化之间的关系已有报道。我们最近发现，内质网应激在体外通过激活非受体膜相关酪氨酸激酶Src，触发保护性信号，称为未折叠蛋白反应(UPR)，并诱导AEC的凋亡和EMT，支持了内质网应激在肺纤维化AEC功能障碍表型中的因果作用。初步数据表明，活性氧(ROS)和b-连环蛋白的激活/与共激活因子CBP的相互作用参与了Src依赖的信号转导。内质网伴侣糖调节蛋白78(GRP78)是内质网稳态的主要调节者，是调节肺泡上皮细胞内质网应激反应的理想靶点。这项建议的总体目标是通过利用肺上皮细胞特异性缺失GRP78的小鼠来调节GRP78，来研究ER应激诱导的上皮异常在纤维化发病机制中的潜在机制。我们假设：(1)GRP78缺失在体内诱导和/或加剧实验性纤维化；(2)GRP78缺乏导致的上皮损伤通过直接作用于上皮细胞(例如，细胞凋亡/内皮细胞)和/或异常的上皮-成纤维细胞串扰而导致纤维化；以及(3)GRP78缺乏对EMT/纤维化的影响是通过Src和/或ROS依赖的β-连环蛋白/CBP信号介导的。我们将使用AEC特异的GRP78基因敲除小鼠，结合临床相关的突变的SP-C外显子4，我们建立的原代AEC体外单层模型，以及ICG-001，一种新的连环蛋白/CBP相互作用的抑制剂，以解决以下特定目标：1.评估GRP78缺失介导的ER应激对可诱导的AEC特异性GRP78基因敲除小鼠肺纤维化的影响；2.探讨ER应激在AEC异常(细胞凋亡、EMT和异常的上皮-成纤维细胞交叉连接)中的作用；以及3.确定ER应激诱导AEC损伤/纤维化的潜在机制。这些研究将为IPF的发病机制提供洞察力，并有助于确定这种不治之症的新治疗靶点。