FGF-dependent regulation of VEGF signaling via transcriptional control of VEGF receptor 2 expression. Mus musculus

Numerous studies have suggested a link between fibroblast growth factor (FGF) and vascular endothelial growth factor (VEGF) signaling pathways; however the nature of this link has not been established. To evaluate this relationship we investigated VEGF signaling in endothelial cells with disrupted FGF signaling in vitro and in vivo. We find that endothelial cells lacking FGF signaling become unresponsive to VEGF due to down regulation of VEGFR2 expression caused by reduced Vegfr2 enhancer activation, which is in turn caused by reduced activation of Ets family transcription factors. In vivo this manifests in the loss of vascular integrity and morphogenesis. Thus, basal FGF stimulation of the endothelium is required for maintenance of VEGFR2 expression and the ability to respond to VEGF stimulation and accounts for the hierarchic control of vascular formation by FGFs and VEGF. Overall design: Primary mouse lung endothelial cells were transduced with either Adeno-Null (empty) or Adeno- dominant negative FGF receptor 1 and harvested 24 hours after transduction. Total RNA was extracted and subjected to the analysis using SuperArray GEArray Q Series Mouse Angiogenesis Gene Array. Comparisons were made between treatments.

多项研究已证实成纤维细胞生长因子（fibroblast growth factor, FGF）与血管内皮生长因子（vascular endothelial growth factor, VEGF）信号通路之间存在关联，但二者关联的具体机制尚未阐明。为明确二者的关联机制，本研究分别在体外与体内模型中，对FGF信号通路受阻的内皮细胞内的VEGF信号通路进行了探究。研究结果显示，缺失FGF信号通路的内皮细胞会对VEGF刺激产生应答障碍，其分子机制为：Vegfr2增强子的激活水平下调，导致血管内皮生长因子受体2（vascular endothelial growth factor receptor 2, VEGFR2）的表达量降低；而Vegfr2增强子激活水平下调的原因，则是Ets家族转录因子（Ets family transcription factors）的激活程度下降。在体内环境中，该表型表现为血管完整性丧失与血管形态发生异常。由此可见，内皮细胞所接受的基础水平FGF刺激，是维持VEGFR2表达以及内皮细胞对VEGF刺激产生应答能力的必要条件，同时也阐明了FGF与VEGF对血管生成的层级调控机制。实验设计：将腺病毒空载体（Adeno-Null）与显性负效FGF受体1（Adeno-dominant negative FGF receptor 1）分别转导原代小鼠肺内皮细胞，并于转导后24小时收集细胞。提取总RNA后，采用SuperArray GEArray Q系列小鼠血管生成基因芯片（SuperArray GEArray Q Series Mouse Angiogenesis Gene Array）进行表达分析，并对不同处理组进行组间比较。