Abstract 14313: Gata6 Promotes Endothelial Cell Function and Survival by Suppression of Transforming Growth Factor-β Dependent Signaling.
Introduction: Growth factors can stimulate angiogenesis, which describes the sprouting of new capillaries from endothelial cells. So far, the transcriptional regulation of endothelial cell function during this process is only incompletely understood. While high expression of the transcription factor Gata6 was previously reported in human umbilical vein endothelial cells (HUVECs), its importance for angiogenic function and endothelial cell survival remained unknown.
Results: We detected Gata6 mRNA and protein expression in HUVECs, human umbilical artery endothelial cells (HUAECs), human cardiac microvascular cells (HCMECs) and also in vascular endothelial cells in mouse tissues in vivo. Stimulation of HUVECs with a growth factor cocktail (containing FCS, EGF and bFGF), led to translocation of Gata6 to the nucleus, enhanced chromatin binding at the promoter region of endothelial Gata target genes (Pecam1, EDN-1 and NOS3; ChIP-assay) and enhanced Gata mediated transcriptional activation (luciferase reporter assay). SiRNA mediated downregulation of Gata6 led to a dramatically reduced capacity of endothelial cells (HUVECs and HCMECs) to proliferate (BrDU incorporation, HUVECs, arbitrary units: siRNA control 170±24 vs. siRNA Gata6 60±12; p<0.05), migrate (migrated HUVECs: siRNA control 139±6 vs. siRNA Gata6 28±2; p<0.05) and form capillary-like tubes on matrigel (HUVECs, number of tubes: siRNA control 21±4 vs. siRNA Gata6 1±1; p<0.05) after growth factor cocktail stimulation. Adenoviral overexpression of Gata6, in turn, enhanced these angiogenic functions, especially in HCMECs. To analyze the effects of Gata6 on survival, we withdrew growth factors for 17 hours, which resulted in a higher rate of apoptotic cell death in HUVECs with reduced Gata6 expression. Mechanistically, Gata6 downregulation led to increased expression of TGFβ1 (3-fold) and TGFβ2 (5-fold), and increased activation of ALK5 and SMAD2 in HUVECs. Suppression of this signaling axis by TGFβ neutralizing antibody or ALK5 inhibition restored angiogenic function and survival in endothelial cells with reduced Gata6 expression.
Conclusion: Gata6 plays a crucial role for endothelial cell function and survival, at least in part, by suppressing autocrine TGFβ/ALK5 signaling.
- © 2010 by American Heart Association, Inc.