Mechtcheriakova D, Wlachos A, Holzmüller H, Binder B R, Hofer E
Department of Vascular Biology and Thrombosis Research at VIRCC, University of Vienna, Vienna, Austria.
Blood. 1999 Jun 1;93(11):3811-23.
Vascular endothelial cell growth factor (VEGF) is a major regulator of angiogenesis. We report here that treatment of endothelial cells with VEGF leads to upregulation of tissue factor mRNA and protein expression on the cell surface. Reporter gene studies show that transcriptional activation of the tissue factor gene by VEGF is mediated by a GC-rich promoter element containing overlapping binding sites for Sp1 and EGR-1. As shown by immunofluorescence and electrophoretic mobility shift assays, upon VEGF treatment EGR-1 rapidly accumulates in the nucleus and binds to its respective recognition site in the tissue factor promoter. Sp1 occupies this element in unstimulated cells and seems to be partially displaced by increasing amounts of EGR-1. Transfection of endothelial cells with an EGR-1 expression plasmid mimics the upregulation of tissue factor transcription observed after VEGF treatment. In contrast, NFkappaB, the major transcription factor involved in tissue factor upregulation by inflammatory stimuli, is not activated by VEGF. These data show that VEGF induces a response in endothelial cells largely distinct from inflammatory stimuli, and suggest that EGR-1 is a major mediator of the activation of the tissue factor and possibly other VEGF-responsive genes.
血管内皮细胞生长因子（VEGF）是血管生成的主要调节因子。我们在此报告，用VEGF处理内皮细胞会导致细胞表面组织因子mRNA和蛋白表达上调。报告基因研究表明，VEGF对组织因子基因的转录激活是由富含GC的启动子元件介导的，该元件包含Sp1和EGR-1的重叠结合位点。如免疫荧光和电泳迁移率变动分析所示，VEGF处理后，EGR-1迅速在细胞核中积累，并与其在组织因子启动子中的相应识别位点结合。Sp1在未受刺激的细胞中占据该元件，并且似乎随着EGR-1量的增加而被部分取代。用EGR-1表达质粒转染内皮细胞可模拟VEGF处理后观察到的组织因子转录上调。相反，参与炎症刺激导致组织因子上调的主要转录因子NFκB不会被VEGF激活。这些数据表明，VEGF在内皮细胞中诱导的反应与炎症刺激有很大不同，并表明EGR-1是组织因子以及可能其他VEGF反应性基因激活的主要介质。
