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

基本信息

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
项目类别：
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

项目摘要

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.

当前的大流行凸显了了解远端肺上皮如何修复的日益紧迫的必要性损伤后，产生表面活性剂的肺泡 2 型肺细胞（AT2 细胞）也会产生气体交换。促进肺泡 1 型肺细胞（AT1 细胞），最近的研究强化了这种脆弱性小鼠损伤研究表明 AT2 细胞通过中间体转变为 AT1 命运。过渡态表现为整合应激反应（ISR）途径的激活，也是一种转录状态我们在继发于病毒性肺炎的纤维化或损伤患者的肺泡上皮细胞中发现了这种病毒。发现综合应激反应抑制剂 (ISRIB) 可以促进 AT2 到 AT1 的转变步骤，最终减轻小鼠模型中的纤维化（Watanabe 等人，PNAS，2021）。 AT2 细胞中 ISR 的持续激活会阻碍肺泡上皮修复，概念上的差距仍然存在：什么上游形态发生事件是否驱动损伤后的应激反应？如何调节？ ISR 改善 AT2 到 AT1 的形态发生转变？我们发现损伤会导致 AT2 急性损伤反应期间的肥大和多倍化，尤其是双核 AT2。分析表明，多倍体的途径是 AT2 至 AT1 扁平化过程中胞质分裂失败。减弱 ISR 会抑制肥大的多倍体 AT2 细胞的丰度。初步数据显示，我们导致肺损伤随着 AT2 细胞的增大和增殖而持续激活它们中的 ISR。压平以修复肺泡上皮，增加有丝分裂滑入多倍体 AT2 细胞的敏感性。因此，目标 1 将确定 ISR 的激活是否支持 AT2 多倍化小鼠和人类肺纤维化的发展将决定 AT2 多倍体是否必要。足以使纤维化恶化以应对随后的损伤。目标 3 将决定 AT2 是否有效。多倍化是由于损伤诱导的信号下游胞质分裂失败导致肌动蛋白崩溃的结果我们自始至终使用 ISRIB 处理来了解指导 AT2 细胞的分子过程。通过修复所需的形态遗传应激 AT2 到 AT1 的转变总体而言，我们建议使用 AT2。细胞分裂本质上很容易受到针对 F-肌动蛋白组织的损伤诱导信号的影响，从而导致有丝分裂失败促进多倍体状态 AT2 多倍体化的一个关键后果是 AT2 的丢失。干细胞女儿，损害未来的再生潜力。