Abstract 592: Enhance Fibroblast Growth Factor Receptor Signaling in VE-Cadherin-RTEF-1 Transgenic Mice
Background: We have recently demonstrated that Related Transcription Enhancer Factor-1 (RTEF-1) is a transcription factor in endothelial cells. We also established that RTEF-1 regulated VEGF promoter activity is enhanced in endothelial cells under hypoxic conditions in vitro. To investigate the role of RTEF-1 in endothelial function in vivo, we used VE-Cadherin promoter to overexpress RTEF-1 in endothelial cells in mice.
Methods and Results: Full length human RTEF-1 cDNA was linked to the 3′ end of VE-Cadherin promoter. The construct was then microinjected into fertilized eggs of FVB mice. Genotyping of the transgenic mice was analyzed by PCR and Southern blot. Expression of RTEF-1 (examined by using western blot and immunohistochemistry), was significantly increased in endothelial rich organs including heart, aorta, kidney and brain in transgenic mice as compared with wild type control mice. VE-Cadherin-RTEF-1 mice and wild-type mice were also subjected to hypoxic conditions for 4 hours. Northern and Western blot analysis showed a significant increase in fibroblast growth factor receptor-1(FGFR-1) mRNA and protein (1.5–2.0 fold) in heart and aortic tissue from VE-Cadherin-RTEF-1 transgenic mice. The increased expression of FGFR-1 was enhanced when the transgenic mice were exposed to 5% oxygen for 4 hours as compared to control mice exposed to room air (21% oxygen) for 4 hours. Additionally, in vitro studies of both Bovine aortic endothelial cells and human umbilical vein endothelial cells demonstrated that transfected RTEF-1 can stimulate FGFR-1 promoter activity (4–5 fold) whereas RTEF-1 siRNA can decrease FGFR-1 promoter activity (3 fold).
Conclusion: Our results indicate that RTEF-1 acts, as a transcriptional stimulator of the FGFR-1 gene in endothelial cells. RTEF-1 may be a strong potential transcriptional factor that regulates FGFR-1 in terms of angiogenic responses to hypoxia.