PKCε activation promotes FGF-2 exocytosis and induces endothelial cell proliferation and sprouting

Protein kinase C epsilon (PKC epsilon) activation controls fibroblast growth factor-2 (FGF-2) angiogenic signaling. Here, we examined the effect of activating PKC epsilon on FGF-2 dependent vascular growth and endothelial activation. psi epsilon RACK, a selective PKC epsilon agonist induces pro-angiogenic responses in endothelial cells, including formation of capillary like structures and cell growth. These effects are mediated by FGF-2 export to the cell membrane, as documented by biotinylation and immunofluorescence, and FGF-2/FGFR1 signaling activation, as attested by ERK1/2-STAT-3 phosphorylation and de novo FGF-2 synthesis. Similarly, vascular endothelial growth factor (VEGF) activates PKC epsilon in endothelial cells, and promotes FGF-2 export and FGF-2/FGFR1 signaling activation. psi epsilon RACK fails to elicit responses in FGF-2(-/-) endothelial cells, and in cells pretreated with methylamine (MeNH2), an exocytosis inhibitor, indicating that both intracellular FGF-2 and its export toward the membrane are required for the psi epsilon RACK activity. In vivo psi epsilon RACK does not induce angiogenesis in the rabbit cornea. However, psi epsilon RACK promotes VEGF angiogenic responses, an effect sustained by endothelial FGF-2 release and synthesis, since anti-FGF-2 antibody strongly attenuates VEGF responses. The results demonstrate that PKC epsilon stimulation promotes angiogenesis and modulates VEGF activity, by inducing FGF-2 release and autocrine signaling. (C) 2013 The Authors. Published by Elsevier Ltd. All rights reserved.