FGF and PDGF regulate myofibroblast differentiation in alveolar regeneration

描述（由申请人提供）：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间隔再生来逆转肺气肿。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重要作用，但我们发现FGF信号调节了肺泡形成和肺泡再生过程中肌成纤维细胞的分化。本研究将确定肌成纤维细胞前体细胞，明确FGF和PDGF信号在分化过程中的作用，为肌成纤维细胞在肺泡形成和新肺泡形成过程中的作用提供新的见解，并为开发新的策略提供新的策略，以靶向前体细胞中适当的信号通路来诱导新隔膜的再生。我们将以PNX为实验工具，结合转基因小鼠技术，对脂肪成纤维细胞进行标记并跟踪其在肺泡发育和再生过程中的分化，验证肺泡再生的新概念模型，并通过转基因小鼠和药物试剂抑制肌成纤维细胞分化，确定FGF和PDGF信号通路在肌成纤维细胞分化过程中的作用。在目的1中，我们将确定间质脂肪成纤维细胞在PNX术后正常肺泡形成和新肺泡形成过程中的作用。用bgal表达永久标记脂肪成纤维细胞及其后代的转基因小鼠将用于PNX术后正常肺泡形成和新肺泡形成期间的谱系追踪研究。在Aim 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，以确定脂肪成纤维细胞在正常肺泡化和代偿性肺生长过程中的细胞命运；鉴定体外诱导SMA表达的FGF配体和受体。在Aim 3中，我们将定义FGF和PDGF信号在分化成肌细胞中弹性蛋白合成中的作用。我们将使用转基因小鼠抑制FGF信号，或特定的PDGFR激酶抑制剂来评估PNX后弹性纤维的组装。这些研究的结果将确定诱导肺泡再生的合适靶细胞和相关信号通路，并有助于制定肺泡组织再生的新策略，以改善儿童支气管肺发育不良和成人慢性阻塞性肺疾病肺气肿的长期后遗症。

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.