Cooperation Of Histone Acetyltransferase P300 And MRTF-A Promotes The Transactivation Of VE-cadherin Gene In Human Umbilical Vein Endothelial Cells

Angiogenesis plays an important role in the organism development and tumor progress. VE-cadherin is a major determinant of endothelial cell contact integrity and is required in vascular development and angiogenesis. However, the regulatory mechanism of VE-cadherin is not clear. MRTF-A, as an essential transcription factor in cardiovascular disease and vascular development, regulates the transcription of many marker genes. This study aimed to investigate cooperation and molecular mechanism of MRTF-A and histone acetyltransferse p300 on regulating VE-cadherin.The expression of MRTF-A in HUVECs were decreased using siRNA for MRTF-A. Knockdown of MRTF-A inhibited the tube-like structure formation in HUVECs by Matrigel assay. The expression of VE-cadherin, which plays an important role in maintaining the endothelial function, was decreased in response to the low expression of MRTF-A. VEGF is a key growth factor, required for endothelial cell growth and angiogenesis. Treatment with VEGF in siMRTF-A-transfected cells more significantly suppressed the expression of VE-cadherin. The above results indicated that MRTF-A regulated angiogenesis in HUVECs by targeting VE-cadherin.There is a CArG box in the promoter of VE-cadherin by sequence analysis. To determine whether MRTF-A can regulate the transcription of VE-cadherin, the luciferase reporter gene plasmid containing the promoter of VE-cadherin was constructed. The luciferase activity assay showed that MRTF-A significantly activate the transcription of VE-cadherin promoter and this activation is in dose-dependent. After mutation of the binding site of MRTF-A in the promoter of VE-cadherin, the transcriptional activation was clearly decreased. In addition, ChIP assay confirmed that MRTF-A could bind to CArG box within the promoter of VE-cadherin in response to VEGF and this action is in dose-dependent. The above results confirmed that VE-cadherin could be a target gene of MRTF-A.Previous studies show that VEGF can promote the recruitment of histone acetyltransferse to chromatin, which will restructure chromatin and activate the transcription. HUVECs were transfected with expression plasmids of MRTF-A and/or p300. The results illustrated that MRTF-A and p300 can significantly promote the transcription and expression of VE-cadherin. ChIP assay showed that cotransfection with the expression plasmids of MRTF-A and p300 enhanced the binding of MRTF-A into CArG box of VE-cadherin promoter. Furthermore, MRTF-A can activate VE-cadherin by recruiting p300 and enhancing the acetylation of H3K9, H3K14 and H4 surrounding the binding site of SRF.