Abstract P261: Endothelial Differentiation Gene-1 Is Involved in Related Transcriptional Enhancer Factor-1--Induced Endothelial Cell Aggregation

We have previously demonstrated that Related Transcriptional Enhancer Factor-1 (RTEF-1) regulated angiogenesis through induction of vascular endothelial growth factor (VEGF) under hypoxic conditions. Recently, we discovered that RTEF-1 accelerated endothelial cell connections and enhanced endothelial cell aggregation. To investigate the mechanism of RTEF-1 in regulated endothelial aggregation, a DNA array analysis was performed in the endothelial cell (HMEC-1) lacking RTEF-1 by its siRNA and resulted in a significant decrease of endothelial differentiation gene -1 (Edg-1). RTEF-1 significantly increase Edg-1 promoter activity (4.10 Fold) and the expression levels of Edg-1 gene are concordant with the RTEF-1 gene in both mRNA and protein levels in cultured endothelial cells as well as in endothelial specific RTEF-1 transgenic mice (VE-Cad-RTEF-1) and RTEF-1 knock out mice (Tie2 Cre :RTEF-1 floxp ) . In Matrigel tube formation assay, over-expression of Edg-1 gene stimulated endothelial cell aggregation, while siRNA of Edg-1 significantly blocked RTEF-1-driven endothelial cell aggregation. Furthermore, using an Edg-1 receptor agonist Sphingosine-1-phosphate (S1P), the acceleration of the proliferation, migration and tube formation were observed, whereas Edg-1 receptor inhibitor Pertussis Toxin (PTX) could block RTEF-1-induced cell aggregation. Our data demonstrates that Edg-1 is a potential target gene of RTEF-1. It is involved in RTEF-1 regulated endothelial cell angiogenesis, specifically in endothelial cell aggregation.