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: 8711552
• 负责人: Beiyun Zhou
• 金额: $ 40.3万
• 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/8711552
• 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（由申请人提供）：特发性肺纤维化/普通间质性肺炎（IPF/UIP）是一种病因不明的破坏性间质性肺疾病，其特征是（肌）成纤维细胞活化/增殖、细胞外基质（ECM）沉积和进行性肺破坏。最近提出了肺泡上皮在 IPF/UIP 发病机制中的核心作用。在这个范例中，受损的肺泡上皮细胞（AEC）通过释放促进成纤维细胞增殖和分化的纤维增殖介质积极参与纤维形成，进而诱导AEC细胞凋亡和/或通过上皮间质转化（EMT）直接产生成纤维细胞。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途径仍不清楚。据报道，内质网（ER）应激与表面活性剂蛋白（SP）突变相关的散发性和家族性肺纤维化之间存在关联。我们最近发现，ER 应激触发了称为未折叠蛋白反应 (UPR) 的保护性信号传导，并通过非受体膜相关酪氨酸激酶 Src 的激活在体外诱导 AEC 中的细胞凋亡和 EMT，这支持了 ER 应激在肺纤维化功能失调的 AEC 表型中的因果作用。初步数据表明，活性氧 (ROS) 和 β-连环蛋白的激活/与共激活剂 CBP 的相互作用参与了 Src 依赖性信号传导。内质网伴侣葡萄糖调节蛋白 78 (GRP78) 是内质网稳态的主要调节因子，因此是调节肺泡上皮内质网应激反应的理想靶点。该提案的总体目标是通过利用肺上皮细胞特异性删除 Grp78 的小鼠来调节 GRP78，研究与纤维化发病机制有关的 ER 应激诱导上皮异常的机制。我们假设 (1) Grp78 的缺失会诱导和/或加剧体内实验性纤维化； (2) GRP78不足诱导的上皮损伤通过对上皮的直接影响（例如细胞凋亡/EMT）和/或异常的上皮-成纤维细胞串扰而导致纤维化； (3) GRP78 不足对 EMT/纤维化的影响是通过 Src 和/或 ROS 依赖性 ¿-连环蛋白/CBP 信号传导介导的。我们将使用 AEC 特异性 Grp78 敲除小鼠，结合临床相关突变体 SP-C¿exon4（我们完善的初级 AEC 体外单层模型）和 ICG-001（一种新型 ¿-catenin/CBP 相互作用抑制剂）来解决以下具体目标： 1. 评估 Grp78 缺失介导的 ER 应激对诱导型肺纤维化的影响 AEC特异性Grp78基因敲除小鼠； 2. 研究 ER 应激在 AEC 异常（细胞凋亡 vs EMT vs 异常上皮成纤维细胞串扰）中的作用，这些异常与可诱导的 AEC 特异性 Grp78 敲除小鼠纤维化有关； 3. 确定 ER 应激引起的 AEC 损伤/纤维化的机制。这些研究将深入了解 IPF 的发病机制，并有助于确定这种不治之症的新治疗靶点。