sVEGFR-1 signaling through 51 integrin

Soluble VEGFR-1 (sVEGFR-1) acts both as a decoy receptor for VEGFs and as an extracellular matrix protein for 51 integrin. A sVEGFR-1-derived peptide that interacts with 51 integrin promotes angiogenesis. However, canonical signal downstream integrin activation is not induced, resulting into lack of focal adhesion maturation. We performed a gene expression profile of endothelial cells adhering on sVEGFR-1 compared to that of cells adhering on fibronectin, the principal 51 integrin ligand. Three protein kinase-C substrates, adducin, MARCKS, and radixin were differently modulated. Adducin and MARCKS were less phosphorylated whereas radixin was higher phosphorylated in sVEGFR-1 adhering cells, the latter leading to prolonged small GTPase Rac1 activation and induction of a pathway involving the heterotrimeric G protein 13. Altogether, our data indicated endothelial cell acquisition of an highly motile phenotype when adherent on sVEGFR-1. Finally, we indicated radixin as accountable for the angiogenic effect of 51 integrin interaction with sVEGFR-1 that in turn depends on an active VEGF-A/VEGFR-2 signaling.

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Orecchia A, Mettouchi A, Uva P, Simon GC, Arcelli D, Avitabile S, Ragone G, Meneguzzi G, Pfenninger KH, Zambruno G, Failla CM