Correct vascular differentiation requires distinct patterns of gene expression in different subtypes of endothelial cells. Members of the ETS transcription factor family are essential for the transcriptional activation of arterial and angiogenesis-specific gene regulatory elements, leading to the hypothesis that they play lineage-defining roles in arterial and angiogenic differentiation directly downstream of VEGFA signalling. However, an alternative explanation is that ETS binding at enhancers and promoters is a general requirement for activation of many endothelial genes regardless of expression pattern, with subtype-specificity provided by additional factors. Here we use analysis of Ephb4 and Coup-TFII (Nr2f2) vein-specific enhancers to demonstrate that ETS factors are equally essential for vein, arterial and angiogenic-specific enhancer activity patterns. Further, we show that ETS factor binding at these vein-specific enhancers is enriched by VEGFA signalling, similar to that seen at arterial and angiogenic enhancers. However, while arterial and angiogenic enhancers can be activated by VEGFA in vivo, the Ephb4 and Coup-TFII venous enhancers are not, suggesting that the specificity of VEGFA-induced arterial and angiogenic enhancer activity occurs via non-ETS transcription factors. These results support a model in which ETS factors are not the primary regulators of specific patterns of gene expression in different endothelial subtypes.

正确的血管分化需要不同亚型内皮细胞的基因表达模式不同。ETS 转录因子家族的成员对于动脉和血管生成特异性基因调控元件的转录激活至关重要，导致假设它们在 VEGFA 信号传导的直接下游的动脉和血管生成分化中发挥谱系定义作用。然而，另一种解释是，ETS 在增强子和启动子上的结合是激活许多内皮基因的一般要求，无论表达模式如何，亚型特异性由其他因素提供。这里我们使用Ephb4和Coup-TFII ( Nr2f2) 静脉特异性增强剂，以证明 ETS 因子对于静脉、动脉和血管生成特异性增强剂活动模式同样必不可少。此外，我们表明在这些静脉特异性增强子上的 ETS 因子结合被 VEGFA 信号丰富，类似于在动脉和血管生成增强子上看到的。然而，虽然动脉和血管生成增强子可以在体内被 VEGFA 激活，但Ephb4和Coup-TFII静脉增强子不能，这表明 VEGFA 诱导的动脉和血管生成增强子活性的特异性是通过非 ETS 转录因子发生的。这些结果支持一个模型，其中 ETS 因子不是不同内皮亚型中特定基因表达模式的主要调节因子。