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 (miRNA) levels by different stimuli may contribute to the modulation of stimulus-induced responses. The miR-17-92 cluster has been linked to tumor development and angiogenesis, but its role in vascular endothelial growth factor-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 on VEGF stimulation of ECs is responsible for Elk-1-mediated transcription activation (chromatin immunoprecipitation 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. Finally, 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 (phosphatase and tensin homolog) is a target of the miR-17-92 cluster and is a crucial mediator of miR-17-92-induced EC 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.
['Chamorro-Jorganes|Aránzazu|A|', 'Lee|Monica Y|MY|', 'Araldi|Elisa|E|', 'Landskroner-Eiger|Shira|S|', 'Fernández-Fuertes|Marta|M|', 'Sahraei|Mahnaz|M|', 'Quiles Del Rey|Maria|M|', 'van Solingen|Coen|C|', 'Yu|Jun|J|', 'Fernández-Hernando|Carlos|C|', 'Sessa|William C|WC|', 'Suárez|Yajaira|Y|']
D000818:Animals D049109:Cell Proliferation D004730:Endothelium, Vascular D005786:Gene Expression Regulation D061307:Human Umbilical Vein Endothelial Cells D006801:Humans D020935:MAP Kinase Signaling System D051379:Mice D018345:Mice, Knockout D035683:MicroRNAs D018919:Neovascularization, Physiologic D042461:Vascular Endothelial Growth Factor A
endothelial cells microRNAs transcription activation cell proliferation vascular endothelial growth factor A