endothelin-1 and phorbol-12-13-didecanoate

We previously reported that endothelin-1 (ET-1) stimulates p44/p42 mitogen-activated protein (MAP) kinase and p38 MAP kinase in osteoblast-like MC3T3-E1 cells. In the present study, we investigated the effect of ET-1 on the synthesis of vascular endothelial growth factor (VEGF) in these cells. ET-1 significantly stimulated VEGF secretion time-dependently 18 hours after the stimulation. The stimulatory effect was dose-dependent in the range between 0.1 nM and 0.1 micro;M. BQ123, an antagonist of endothelin(A) (ET(A)) receptor, inhibited the ET-1-induced VEGF secretion. The ET-1-induced VEGF secretion was suppressed by SB203580 and PD169316, inhibitors of p38 MAP kinase, but not PD98059, an inhibitor of the upstream kinase that activates p44/p42 MAP kinase. 12-O-Tetradecanoylphorbol-13-acetate (TPA), a protein kinase C (PKC)-activating phorbol ester, stimulated VEGF secretion. Calphostin C, a specific PKC inhibitor, suppressed the VEGF secretion by ET-1. TPA-induced VEGF secretion was suppressed by SB203580. Taken together, our results strongly suggest that ET-1 stimulates VEGF synthesis via ET(A) receptor in osteoblasts and that p38 MAP kinase is involved at a point downstream from PKC in the VEGF synthesis.

Topics: Animals; Endothelial Growth Factors; Endothelin-1; Enzyme Inhibitors; Estrenes; Flavonoids; Gene Expression Regulation; Imidazoles; Lymphokines; MAP Kinase Signaling System; Mice; Mitogen-Activated Protein Kinases; Naphthalenes; Osteoblasts; p38 Mitogen-Activated Protein Kinases; Phorbol Esters; Protein Kinase C; Pyridines; Pyrrolidinones; Receptor, Endothelin A; Receptors, Endothelin; Tetradecanoylphorbol Acetate; Vascular Endothelial Growth Factor A; Vascular Endothelial Growth Factors