VEGF-Induced Expression of miR-17~92 Cluster in Endothelial Cells is Mediated by ERK/ELK1 Activation and Regulates Angiogenesis
Rationale: Several lines of evidence indicate that the regulation of microRNA levels by different stimuli may contribute to the modulation of stimulus-induced responses. The microRNA-17~92 (miR-17~92) cluster has been linked to tumor development and angiogenesis, but its role in VEGF-induced endothelial cell (EC) functions is unclear and its regulation is unknown.
Objective: The purpose of this study was to elucidate the mechanism by which VEGF regulates the expression of miR-17~92 cluster in ECs and determine its contribution to the regulation of endothelial angiogenic functions, both in vitro and in vivo. This was done by analyzing the effect of postnatal inactivation of miR-17~92 cluster in the endothelium (miR-17~92 iEC-KO mice) on developmental retinal angiogenesis, VEGF-induced ear angiogenesis, and tumor angiogenesis.
Methods and Results: Here we show that Erk/Elk1 activation upon VEGF stimulation of ECs is responsible for Elk-1-mediated transcription activation (ChIP analysis) of the miR-17~92 cluster. Furthermore, we demonstrate that VEGF-mediated upregulation of the miR-17~92 cluster in vitro is necessary for EC proliferation and angiogenic sprouting. Lastly, we provide genetic evidence that miR-17~92 iEC-KO mice have blunted physiological retinal angiogenesis during development and diminished VEGF-induced ear angiogenesis and tumor angiogenesis. Computational analysis and rescue experiments show that PTEN is a target of the miR-17~92 cluster and is a crucial mediator of miR-17-92-induced endothelial cell proliferation. However, the angiogenic transcriptional program is reduced when miR-17~92 is inhibited.
Conclusions: Taken together, our results indicate that VEGF-induced miR-17~92 cluster expression contributes to the angiogenic switch of ECs and participates in the regulation of angiogenesis.
- retinal vasculature
- tumor angiogenesis
- endothelial cell
- vascular endothelial growth factor
- Received August 11, 2015.
- Revision received October 11, 2015.
- Accepted October 15, 2015.
Circulation Research is published on behalf of the American Heart Association, Inc., by Wolters Kluwer. This is an open access article under the terms of the Creative Commons Attribution Non-Commercial-NoDervis License (http://creativecommons.org/licenses/by-nc-nd/3.0/), which permits use, distribution, and reproduction in any medium, provided that the original work is properly cited, the use is noncommercial, and no modifications or adaptations are made.