FGF and PDGF regulate myofibroblast differentiation in alveolar regeneration

描述（由申请方提供）：由肺上皮损伤或发育缺陷引起的肺部疾病，包括COPD、肺气肿、肺纤维化和支气管肺发育不良，可导致显著的发病率和死亡率。一个有吸引力的治疗目标是通过肺泡隔的再生来逆转肺气肿。然而，在肺发育和肺再生过程中导致肺泡分隔的细胞和分子事件知之甚少。需要更多的科学研究来确定需要刺激或抑制以促进肺泡再生的适当细胞，基因和途径。虽然其他实验室已经证明间质肌成纤维细胞在肺发育过程中起着重要作用，但我们发现FGF信号转导在肺泡化和肺泡再生过程中调节肌成纤维细胞的分化。拟议的研究将确定肌成纤维细胞前体，并确定FGF和PDGF信号在此分化过程中的作用，以提供对肌成纤维细胞在肺泡化和新肺泡化过程中的作用的新见解，并能够开发新的策略，以靶向前体细胞中的适当信号通路，以诱导新隔膜的再生长。我们将测试一个新的概念模型的肺泡再生作为一个实验工具，使用PNX作为沿着转基因小鼠技术来标记脂成纤维细胞，并遵循其分化过程中肺泡发育和再生，并确定FGF和PDGF信号通路的作用，在肌成纤维细胞分化过程中，通过使用转基因小鼠和药理学试剂来抑制肌成纤维细胞分化。在目标1中，我们将确定间质脂肪成纤维细胞在正常肺泡形成和PNX后新肺泡形成中的作用。永久标记脂成纤维细胞及其后代的bgal表达的转基因小鼠将用于在PNX后的正常肺泡形成和新肺泡形成期间进行谱系追踪研究。在目标2中，我们将确定FGF信号在新肺泡形成过程中肌成纤维细胞的分化和功能中的作用。使用表达显性阴性FGFR的转基因小鼠，我们将进行谱系追踪研究，以确定正常肺泡形成和代偿性肺生长期间脂肪成纤维细胞的细胞命运;并鉴定诱导体外SMA表达的FGF配体和受体。在目标3中，我们将定义FGF和PDGF信号传导在分化的肌成纤维细胞中对弹性蛋白合成的作用。我们将使用转基因小鼠来抑制FGF信号传导，或使用特异性PDGFR激酶抑制剂来评估PNX后的弹性纤维组装。拟议研究的结果将确定诱导肺泡再生的适当靶细胞和相关信号通路，并帮助开发再生肺泡组织的新策略，以改善儿童支气管肺发育不良和成人COPD肺气肿的长期后遗症。 公共卫生相关性：肺疾病，如COPD、肺气肿和支气管肺发育不良，起源于肺泡间隔的丧失或间隔壁的重塑过程。目前还没有有效的治疗方法来再生肺泡隔。本提案中概述的研究将使用转基因小鼠模型和体外实验来专门解决间质肌成纤维细胞的分化过程，这已被证明是肺发育和肺再生过程中肺泡分隔的关键步骤。成功完成拟议的研究将确定肌成纤维细胞祖细胞和新的，潜在的治疗剂，以诱导成人肺肺泡再生。

DESCRIPTION (provided by applicant): Lung diseases that arise from injury to or defective development of the pulmonary epithelium including COPD, emphysema, pulmonary fibrosis, and bronchopulmonary dysplasia cause significant morbidity and mortality. An attractive therapeutic goal would be the reversal of emphysema through regeneration of alveolar septae. However, little is known about the cellular and molecular events that lead to alveolar septation during lung development and lung regeneration. More scientific research is needed to identify the appropriate cells, genes and pathways that need to be stimulated or inhibited to promote alveolar regeneration. While other labs have demonstrated that the interstitial myofibroblast plays an important role during lung development we showed that FGF signaling regulates the differentiation of the myofibroblast during alveolarization and during alveolar regeneration. The proposed research will identify the myofibroblast precursor and define the role of FGF and PDGF signaling in this differentiation process to provide new insights into the role of the myofibroblast during alveolarization and neoalveolarization and enable the development of new strategies to target the appropriate signaling pathway in precursor cells to induce regrowth of new septae. We will test a new conceptual model of alveolar regeneration by using PNX as an experimental tool along with transgenic mouse technology to label lipofibroblasts and follow their differentiation during alveolar development and regeneration and determine the role of FGF and PDGF signaling pathways during myofibroblast differentiation by using transgenic mice and pharmacological reagents to inhibit myofibroblast differentiation. In Aim 1 we will determine the role of the interstitial lipofibroblast during normal alveolarization and neoalveolarization after PNX. Transgenic mice that permanently label lipofibroblasts and their progeny with bgal expression will be used to perform lineage-tracing studies during normal alveolarization and neo-alveolarization after PNX. In Aim 2 we will determine the role of FGF signaling in the differentiation and function of the myofibroblast during neoalveolarization. Using transgenic mice that express a dominant negative FGFR we will perform lineage-tracing studies to determine the cell fate of the lipofibroblast during normal alveolarization and compensatory lung growth; and identify the FGF ligands and receptors that induce (SMA expression in vitro. In Aim 3 we will define the role of FGF and PDGF signaling on elastin synthesis in the differentiating myofibroblast. We will use transgenic mice to inhibit FGF signaling, or a specific PDGFR kinase inhibitor to assess elastic fiber assembly after PNX. The results from the proposed studies will identify the appropriate target cells and relevant signaling pathway that induce alveolar regeneration and help develop new strategies to regenerate alveolar tissue to improve the long-term sequelae of bronchopulmonary dysplasia in children and emphysema in the adult lung with COPD. PUBLIC HEALTH RELEVANCE: Lung diseases, such as COPD, emphysema and bronchopulmonary dysplasia, originate from the loss of alveolar septa or remodeling processes of septal walls. Currently there are no effective therapies to regenerate alveolar septae. The studies outlined in this proposal will use transgenic mouse models and in vitro experiments to specifically address the differentiation process of the interstitial myofibroblasts, which has been shown to be a critical step for alveolar septation during lung development and lung regeneration. Successful completion of the proposed studies will identify the myofibroblast progenitor cell and novel, potentially therapeutic agents to induce alveolar regeneration in an adult lung.