The role of transcription factor MEOX2 in lipofibroblast function during alveolarization

项目摘要 肺脂肪成纤维细胞（LF）位于远端肺间质，支持肺泡上皮细胞 在两种成人发作的纤维化肺病（如特发性肺纤维化，IPF）中的稳态和修复 和新生儿肺部疾病（如支气管肺发育不良，BPD）。具体而言，LFs：1）摄取和 在肺泡化过程中将脂肪酸转移到肺泡2型（AT 2）上皮细胞以产生表面活性剂，和 2)提供刺激肺泡1型（AT 1）和AT 2增殖的旁分泌配体如FGF 10， 分化更好地理解肺脂肪成纤维细胞表型的转录调控 将导致BPD和IPF靶向治疗的发展。转录因子MEOX 2是一个信号 如通过公开可用的RNA测序数据集鉴定的，鼠发育成脂纤维细胞的基因。在 在其他器官系统中，MEOX 2控制心血管内皮细胞中的脂肪酸摄取，对于 棕色脂肪脂肪形成，并且对于早期肢体中的间充质增殖和分化至关重要 发展尽管MEOX 2在非小细胞肺癌中上调，但MEOX 2在肺腺癌中的作用与MEOX 2的表达无关。 发展完全未知。我们预测MEOX 2将在脂肪成纤维细胞分化中发挥作用， 因此我们努力获得MEOX 2上游和下游功能的初步数据。PPAR信号是 一种已知的脂肪成纤维细胞分化的活化剂，因此我们处理人PDGFR α +胎肺成纤维细胞（IMR 90 细胞）与泛-PPAR激活剂二甲双胍，其诱导MEOX 2的表达。此外，我们执行了一个 在人MEOX 2基因座进行转录因子基序搜索，并鉴定了一种假定的过氧化物酶体增殖物 响应元件（PPRE）。然后，我们在IMR 90细胞中过表达MEOX 2，并确定MEOX 2是 足以诱导脂肪成纤维细胞标记基因PLIN 2和TCF 21的表达。这个问题的核心假设是 授权的一个重要特征是MEOX 2直接受PPARA信号调节，并且对于建立MEOX 2是必要且充分的。 脂肪成纤维细胞谱系和肺泡化过程中的功能。目标1将调查假定的PPRE是否为 通过使用分子遗传学方法诱导MEOX 2表达所必需和充分的 在永生化的人肺成纤维细胞中。目的2将研究MEOX 2是否是诱导 脂肪成纤维细胞基因表达、脂肪酸（FA）摄取和转运以及肺泡上皮细胞的支持 通过1）与瞬时MEOX 2敲除和过表达组合的体外测定来分化 构建体，和2）在早期肺泡化期间的体内条件成纤维细胞特异性MEOX 2敲除。我们 长期目标是鉴定MEOX 2作为肺间充质发育中的转录因子的作用， 以期发现慢性新生儿和成人肺部疾病的治疗靶点。本培训计划 结合分子、细胞和发育生物学，回答有关肺的基本问题。 成纤维细胞生物学我的职业目标是成为理解转录因子如何调节的领导者 发展中的细胞分化，以及它们如何成为疾病治疗的靶点。

Project Summary Pulmonary lipofibroblasts (LFs) that reside in the distal lung mesenchyme support alveolar epithelial cell homeostasis and repair in both adult-onset fibrotic lung diseases (such as idiopathic pulmonary fibrosis, IPF) and neonatal lung diseases (such as bronchopulmonary dysplasia, BPD). Specifically, LFs: 1) uptake and transfer fatty acids to alveolar type 2 (AT2) epithelial cells during alveolarization for surfactant production, and 2) provide paracrine ligands such as FGF10 that stimulate alveolar type 1 (AT1) and AT2 proliferation and differentiation. A better understanding of the transcriptional regulation of the pulmonary lipofibroblast phenotype will lead to the development of targeted therapies for BPD and IPF. Transcription factor MEOX2 is a signature gene of the murine developmental lipofibroblast, as identified by publicly available RNA-sequencing datasets. In other organ systems, MEOX2 controls fatty acid uptake in cardiovascular endothelial cells, is necessary for brown fat adipogenesis, and is critical for mesenchymal proliferation and differentiation in early limb development. Although MEOX2 is upregulated in non-small cell lung cancer, the role of MEOX2 in lung development is completely unknown. We predicted that MEOX2 would have a role in lipofibroblast differentiation, so we strove to generate preliminary data on MEOX2’s upstream and downstream function. PPAR signaling is a known activator of lipofibroblast differentiation, so we treated human PDGFRa+ fetal lung fibroblasts (IMR90 cells) with pan-PPAR activator metformin, which induced expression of MEOX2. Additionally, we performed a transcription factor motif search at the human MEOX2 locus and identified a putative peroxisome proliferator response element (PPRE). We then overexpressed MEOX2 in IMR90 cells and determined that MEOX2 is sufficient to induce expression of lipofibroblast signature genes PLIN2 and TCF21. The central hypothesis of this grant is that MEOX2 is directly regulated by PPARA signaling and is necessary and sufficient for establishment of the lipofibroblast lineage and function during alveolarization. Aim 1 will investigate if the putative PPRE is necessary and sufficient for induction of MEOX2 expression through the use of molecular genetic approaches in immortalized human lung fibroblasts. Aim 2 will investigate if MEOX2 is necessary and sufficient to induce lipofibroblast gene expression, fatty acid (FA) uptake and transfer, and support of alveolar epithelial differentiation through 1) in vitro assays combined with transient MEOX2 knockout and overexpression constructs, and 2) an in vivo conditional fibroblast specific MEOX2 knockout during early alveolarization. Our long-term goal is to identify MEOX2’s role as a transcription factor in the development of the lung mesenchyme, with the hope of discovering therapeutic targets for chronic neonatal and adult lung diseases. This training plan combines, molecular, cellular, and developmental biology to answer fundamental questions about pulmonary fibroblast biology. My career goal is to become a leader in understanding how transcription factors regulate cellular differentiation in development, and how they may be targetable for therapies in disease.