Fish Jason E, Cantu Gutierrez Manuel, Dang Lan T, Khyzha Nadiya, Chen Zhiqi, Veitch Shawn, Cheng Henry S, Khor Melvin, Antounians Lina, Njock Makon-Sébastien, Boudreau Emilie, Herman Alexander M, Rhyner Alexander M, Ruiz Oscar E, Eisenhoffer George T, Medina-Rivera Alejandra, Wilson Michael D, Wythe Joshua D
Toronto General Hospital Research Institute, University Health Network, Toronto M5G 2C4, Canada
Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto M5S 1A8, Canada.
Development. 2017 Jul 1;144(13):2428-2444. doi: 10.1242/dev.146050. Epub 2017 May 23.
The transcriptional pathways activated downstream of vascular endothelial growth factor (VEGF) signaling during angiogenesis remain incompletely characterized. By assessing the signals responsible for induction of the Notch ligand delta-like 4 (DLL4) in endothelial cells, we find that activation of the MAPK/ERK pathway mirrors the rapid and dynamic induction of transcription and that this pathway is required for expression. Furthermore, VEGF/ERK signaling induces phosphorylation and activation of the ETS transcription factor ERG, a prerequisite for induction. Transcription of coincides with dynamic ERG-dependent recruitment of the transcriptional co-activator p300. Genome-wide gene expression profiling identified a network of VEGF-responsive and ERG-dependent genes, and ERG chromatin immunoprecipitation (ChIP)-seq revealed the presence of conserved ERG-bound putative enhancer elements near these target genes. Functional experiments performed and confirm that this network of genes requires ERK, ERG and p300 activity. Finally, genome-editing and transgenic approaches demonstrate that a highly conserved ERG-bound enhancer located upstream of (which encodes a transcription factor implicated in sprouting angiogenesis) is required for its VEGF-mediated induction. Collectively, these findings elucidate a novel transcriptional pathway contributing to VEGF-dependent angiogenesis.
血管生成过程中血管内皮生长因子（VEGF）信号下游激活的转录途径仍未完全明确。通过评估在内皮细胞中诱导Notch配体Delta样4（DLL4）的信号，我们发现MAPK/ERK途径的激活反映了转录的快速动态诱导，并且该途径是DLL4表达所必需的。此外，VEGF/ERK信号诱导ETS转录因子ERG的磷酸化和激活，这是DLL4诱导的先决条件。DLL4的转录与转录共激活因子p300的动态ERG依赖性募集相吻合。全基因组基因表达谱分析确定了一个VEGF反应性和ERG依赖性基因网络，ERG染色质免疫沉淀（ChIP）-seq揭示了这些靶基因附近存在保守的ERG结合推定增强子元件。进行的功能实验证实，这个基因网络需要ERK、ERG和p300的活性。最后，基因组编辑和转基因方法表明，位于DLL4（其编码一种参与发芽血管生成的转录因子）上游的一个高度保守的ERG结合增强子是其VEGF介导诱导所必需的。这些发现共同阐明了一条有助于VEGF依赖性血管生成的新转录途径。
