Fibroblast Growth factor signaling in lipofibroblast formation and transdifferentiation during normal lung development and fibrosis

在这项提案中，我们将测试的总体假设，即一种生长因子称为成纤维细胞生长因子10（FGF 10）控制的承诺，脂肪成纤维细胞祖细胞进入脂肪成纤维细胞谱系在肺发育过程中，并防止转分化的脂肪成纤维细胞活化成肌纤维细胞在肺纤维化。我们将使用最近开发的小鼠品系，其中Cre-ERT 2在内源性Fgf 10调控序列的控制下（这个新的小鼠系被称为Fgf 10 Cre-ERT 2），以证明在假腺期位于间充质中并表达Fgf 10的特定细胞群（E11.5-E16）含有在晚期胎儿/早期纳塔尔后阶段（E18.5-P5）的脂肪成纤维细胞的祖细胞。我们还将确定间充质中自分泌FGF 10信号环在控制这些早期间充质祖细胞分化为脂肪成纤维细胞谱系中所起的潜在功能作用。此外，我们将使用Fgf 10 Cre-ERT 2系来确定这些Fgf 10阳性祖细胞是否可以在几种肺纤维化实验模型中在肺中产生活化的肌成纤维细胞。我们还将测试Fgf 10的过表达是否阻止这些肺纤维化模型中活化的肌成纤维细胞的形成。最后，我们将通过一种更具转化性的方法来验证我们在小鼠中的观察结果。我们将利用位于吉森的Justus Liebig大学的人体材料生物库（IPF与供体）来确定FGF配体、其受体和相关下游靶点以及脂肪成纤维细胞标志物的表达。我们还将使用来自IPF与供体的间质成纤维细胞的原代培养物，并通过qPCR定量这些基因的表达，以及监测它们对不同生长因子治疗（包括FGF 10）的体外反应。

In this proposal, we will test the overall hypothesis that a growth factor called Fibroblast Growth factor 10 (FGF10) controls the commitment of lipofibroblast progenitors into the lipofibroblast lineage during lung development and prevents the transdifferentiation of lipofibroblasts to activated myofibroblast during lung fibrosis. We will use a recently developed mouse strain where Cre-ERT2 is under the control of endogenous Fgf10 regulatory sequences (this new mouse line is called Fgf10Cre-ERT2) to demonstrate that a specific cell population located in the mesenchyme and expressing Fgf10 during the pseudoglandular stage (E11.5-E16) contains the progenitors for the lipofibroblasts at late fetal/early post natal stages (E18.5-P5). We will also determine the potential functional role played by an autocrine FGF10 signaling loop in the mesenchyme in controlling the differentiation of these early mesenchymal progenitors to the lipofibroblast lineage. Additionally, we will use the Fgf10Cre-ERT2 line to determine whether these Fgf10-positive progenitor cells can give rise to activated myofibroblasts in the lung in several experimental models of lung fibrosis. We will test also if overexpression of Fgf10 prevents the formation of activated myofibroblasts in these models of lung fibrosis. Finally, we will validate our observations made in mice by carrying a more translational approach. We will take advantage of the Biobank for human material (IPF versus donor) at Justus Liebig University in Giessen to determine the expression of FGF ligands, their receptors and associated downstream targets as well as lipofibroblast markers. We will also use primary culture of interstitial fibroblasts from IPF versus donors and quantify the expression of these genes by qPCR as well as monitor their in vitro response to different growth factors treatments including FGF10.