Alveolar epithelial stress-induced polyploidization in lung injury and repair

肺损伤和修复中肺泡上皮应激诱导的多倍化

• 批准号: 10621898
• 负责人: Cara J Gottardi
• 金额: $ 61.77万
• 依托单位: NORTHWESTERN UNIVERSITY AT CHICAGO
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-05-15 至 2026-04-30
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10621898
• 关键词: 3-Dimensional; AGTR2 gene; Actins; Acute; Address; Alveolar; Automobile Driving; COVID-19 pneumonia; Cell Culture Techniques; Cell Differentiation process; Cell division; Cells; Complex; Credentialing; Cytokinesis; Cytoskeleton; Data; Disease; Distal; Epithelial Cells; Epithelium; Event; F-Actin; Failure; Fibrosis; Future; Gases; Genetic Transcription; Homeostasis; Human; Hypertrophy; Individual; Injury; Knowledge; Link; Lung; Lung diseases; Mitotic; Modeling; Molecular; Mus; Organism; Pathway interactions; Patients; Physiology; Polyploidy; Predisposition; Process; Publishing; Pulmonary Fibrosis; Route; Secondary to; Semaphorins; Signal Induction; Stress; Testing; Tissues; Transitional Cell; Viral Pneumonia; alveolar epithelium; alveolar homeostasis; biological adaptation to stress; current pandemic; daughter cell; epithelial repair; ex vivo imaging; experimental study; gain of function; human tissue; improved; inhibitor; injury and repair; loss of function; lung development; lung injury; lung repair; mouse model; pneumocyte; progenitor; programs; regeneration potential; repaired; response; response to injury; stem cells; surfactant; transcriptomics; transdifferentiation

The current pandemic highlights a growing imperative to understand how the distal lung epithelium repairs after injury. While surfactant producing-alveolar type 2 pneumocytes (AT2 cells) also give rise to gas-exchange promoting alveolar type 1 pneumocytes (AT1 cells), recent studies reinforce the vulnerability of this morphogenetic step. Mouse injury studies reveal that AT2 cells convert to an AT1 fate through an intermediate transition-state manifesting activation of integrated stress response (ISR) pathways, a transcriptional state also found in alveolar epithelial cells from patients with fibrosis or injury secondary to viral pneumonia. We have discovered that an Inhibitor of the Integrated Stress Response (ISRIB) can facilitate the AT2-to-AT1 transition step, ultimately attenuating fibrosis in murine models (Watanabe et al., PNAS, 2021). While these data suggest persistent activation of the ISR in AT2 cells can thwart alveolar epithelial repair, conceptual gaps remain: What are the upstream morphogenetic events driving this stress response after injury? And how does modulating the ISR improve the AT2-to-AT1 morphogenetic transition? We have discovered that injury leads to AT2 hypertrophy and polyploidization—notably binucleated AT2s—during the acute injury response. Ex vivo analysis suggests the route to polyploidy is via failed cytokinesis during the AT2-to-AT1 flattening process. Attenuating the ISR inhibits the abundance of hypertrophic, polyploid AT2 cells. Based on our published and preliminary data, we hypothesize lung injury persistently activates the ISR in AT2 cells as they enlarge and flatten to repair the alveolar epithelium, increasing the susceptibility to mitotic slippage into polyploid AT2 cells. Accordingly, Aim 1 will determine whether activation of the ISR underpins AT2 polyploidization during the development of lung fibrosis in mice and humans. Aim 2 will determine whether AT2 polyploidy is necessary or sufficient to worsen fibrosis in response to subsequent injury. Aim 3 will determine whether AT2 polyploidization results from failed cytokinesis downstream of injury-induced signals that collapse the actin cytoskeleton. We use treatment with ISRIB throughout to understand molecular processes that guide AT2 cells through the morpho-genetically stressful AT2-to-AT1 transition required for repair. Overall, we propose AT2 cell divisions are intrinsically vulnerable to injury-induced signals that target F-actin organization, leading to mitotic failures that promote the polyploid state. A key consequence of AT2 polyploidization is loss of the AT2 stem cell daughter, compromising future regenerative potential.

当前的大流行强调了越来越需要了解盘状肺上皮的维修 受伤后。而表面活性剂生产 - 肺泡2型肺细胞（AT2细胞）也会引起气体交换 促进1型肺泡1肺细胞（AT1细胞），最近的研究增强了这种脆弱性 形态发生步骤。小鼠损伤研究表明，AT2细胞通过中间体转化为AT1命运 过渡状态表现出综合应力响应（ISR）途径的激活，也是转录状态 在病毒性肺炎继发于纤维化或损伤患者的肺泡上皮细胞中发现。我们有 发现综合应力响应（ISRIB）的抑制剂可以促进AT2-to-AT1转变 步骤，最终削弱了鼠模型中的纤维化（Watanabe等，PNAS，2021）。这些数据暗示 AT2细胞中ISR的持续激活可以阻止肺泡上皮修复，概念差距仍然存在：什么 上游的形态发生事件是否在受伤后推动这种压力反应？以及如何调节 ISR改善了AT2至AT1形态发生过渡？我们发现伤害导致AT2 在急性损伤反应下，肥大和多倍体化（尤其是对AT2）。前体 分析表明，在AT2到AT1扁平过程中，多倍体的途径是通过失败的细胞因子。 减弱ISR抑制肥厚的多倍体AT2细胞的抽象。根据我们出版的 初步数据，我们假设肺损伤在扩大时会持续激活AT2细胞中的ISR 平坦以修复牙槽上皮，从而增加了对多倍体AT2细胞的有丝分裂滑移的敏感性。 根据，AIM 1将确定在ISR基础上激活ISR基础AT2多倍化是否在 小鼠和人类肺纤维化的发展。 AIM 2将确定AT​​2多倍体是否需要或 足以应对随后的损伤的纤维化。 AIM 3将确定AT​​2是否 损伤诱导的信号下游失败的肌动蛋白的细胞因子失败导致多倍体化 细胞骨架。我们在整个过程中使用Isrib的处理来了解指导AT2细胞的分子过程 修复所需的AT2到AT1转变，通过形态生殖压力。总体而言，我们建议AT2 细胞分裂本质上容易受到靶向F-肌动蛋白组织的损伤引起的信号，导致 促进多倍体状态的有丝分裂失败。 AT2多倍化的关键结果是AT2的损失 干细胞女儿，损害未来再生潜力。