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.

当前的大流行突出了了解远端肺上皮如何修复的日益迫切性 伤后而产生表面活性剂的肺泡2型肺细胞（AT 2细胞）也引起气体交换 促进肺泡1型肺细胞（AT 1细胞），最近的研究加强了这种脆弱性， 形态发生步骤小鼠损伤研究表明，AT 2细胞通过中间体转化为AT 1命运 过渡状态显示整合应激反应（ISR）途径的激活，转录状态也 在纤维化或继发于病毒性肺炎的损伤患者的肺泡上皮细胞中发现。我们有 发现综合应激反应抑制剂（ISRIB）可以促进AT 2到AT 1的转变 步骤，最终减弱鼠模型中的纤维化（Watanabe等人，PNAS，2021）。虽然这些数据表明 AT 2细胞中ISR的持续激活可以阻碍肺泡上皮修复，但概念上的差距仍然存在：什么 是上游形态发生事件驱动了损伤后的应激反应吗？如何调节 ISR促进AT 2向AT 1的形态发生转变？我们已经发现，损伤导致AT 2 肥大和多倍化-特别是双核AT 2-在急性损伤反应。离体 分析表明，多倍体的途径是通过在AT 2-到-AT 1扁平化过程中失败的胞质分裂。 减弱ISR可抑制肥大、多倍体AT 2细胞的丰度。根据我们发布的和 初步数据，我们假设肺损伤持续激活ISR在AT 2细胞，因为他们扩大， 扁平化以修复肺泡上皮，增加有丝分裂滑入多倍体AT 2细胞的易感性。 因此，目的1将确定ISR的激活是否支持AT 2在细胞分裂期间的多倍化。 在小鼠和人类中肺纤维化的发展。目的2将确定AT 2多倍性是否是必要的， 足以使纤维化恶化以响应随后的损伤。目标3将决定AT 2是否 多倍化是由于损伤诱导信号下游的胞质分裂失败， 细胞骨架我们在整个过程中使用ISRIB治疗，以了解指导AT 2细胞的分子过程 通过修复所需的形态遗传应激AT 2到AT 1的转变。总的来说，我们建议AT 2 细胞分裂本质上容易受到损伤诱导的信号的影响，这些信号靶向F-肌动蛋白组织，导致 促进多倍体状态的有丝分裂失败。AT 2多倍化的一个关键结果是AT 2基因的缺失。 干细胞子细胞，损害未来的再生潜力。