Abstract
Tumor necrosis factor superfamily-15 (TNFSF15; VEGI; TL1A) is a negative modulator of angiogenesis for blood vessel homeostasis and is produced by endothelial cells in a mature vasculature. It is known to be downregulated by vascular endothelial growth factor (VEGF), a major regulator of neovascularization but the mechanism of this interaction is unclear. Here we report that VEGF is able to stimulate the production of two microRNAs, miR-20a and miR-31, which directly target the 3'-UTR of TNFSF15. Additionally, we show that two VEGF-stimulated cell growth signals, Erk and Akt, are responsible for promoting the expression of miR-20a and miR-31. Treatment of human umbilical vein endothelial cells (HUVECs) with Akt inhibitor LY294002 results in diminished miR-20a and miR-31 production, while Erk inhibitor U0126 prevented VEGF-stimulated expression of miR-20a but not that of miR-31. Furthermore, inactivation of either Erk or Akt signals restores TNFSF15 gene expression. In an angiogenesis assay, elevated miR-20a or miR-31 levels in HUVECs leads to enhancement of capillary-like tubule formation in vitro, whereas lowered miR-20a and miR-31 levels results in an inhibition. These findings are consistent with the view that miR-20a and miR-31 mediate VEGF-induced downregulation of TNFSF15. Targeting these microRNA molecules may therefore provide an effective approach to inhibit angiogenesis.