p38 MAP kinase regulates BMP-4-stimulated VEGF synthesis via p70 S6 kinase in osteoblasts.
We previously reported that p70 S6 kinase takes part in bone morphogenetic protein-4 (BMP-4)-stimulated vascular endothelial growth factor (VEGF) synthesis in osteoblast-like MC3T3-E1 cells. Recently, we showed that BMP-4-induced osteocalcin synthesis is regulated by p44/p42 MAP kinase and p38 MAP kinase in these cells. In the present study, we investigated whether the MAP kinases are involved in the BMP-4-stimulated synthesis of VEGF in MC3T3-E1 cells. PD-98059 and U-0126, inhibitors of the upstream kinase of p44/p42 MAP kinase, failed to affect BMP-4-stimulated VEGF synthesis. SB-203580 and PD-169316, inhibitors of p38 MAP kinase, significantly reduced VEGF synthesis, whereas SB-202474, a negative control for p38 MAP kinase inhibitor, had little effect on VEGF synthesis. The BMP-4-stimulated phosphorylation of p38 MAP kinase was not affected by rapamycin, an inhibitor of p70 S6 kinase. On the contrary, SB-203580 and PD-169316 reduced the BMP-4-stimulated phosphorylation of p70 S6 kinase. In addition, anisomycin, an activator of p38 MAP kinase, phosphorylates p70 S6 kinase, and the phosphorylation was suppressed by SB-203580. LY-294002, an inhibitor of phosphatidylinositol 3-kinase, failed to suppress the phosphorylation of p38 MAP kinase induced by BMP-4. Not BMP-4 but anisomycin weakly induced the phosphorylation of phosphoinositide-dependent kinase-1. However, anisomycin had little effect on phosphorylation of either Akt or the mammalian target of rapamycin. Taken together, our results suggest that p38 MAP kinase functions in BMP-4-stimulated VEGF synthesis as a positive regulator at a point upstream from p70 S6 kinase in osteoblasts.
Tokuda
Haruhiko
H
Department of Internal Medicine, Chubu National Hospital, National Institute for Longevity Sciences, Obu, Aichi 474-8511, Japan.
Hatakeyama
Daijiro
D
Shibata
Toshiyuki
T
Akamatsu
Shigeru
S
Oiso
Yutaka
Y
Kozawa
Osamu
O
D000818:Animals; D000841:Anisomycin / Q000494:pharmacology; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D015153:Blotting, Western; D055415:Bone Morphogenetic Protein 4; D019485:Bone Morphogenetic Proteins / Q000494:pharmacology*; D002070:Butadienes / Q000494:pharmacology; D002460:Cell Line; D002867:Chromones / Q000494:pharmacology; D016228:Endothelial Growth Factors / Q000096:biosynthesis*; D004797:Enzyme-Linked Immunosorbent Assay; D005419:Flavonoids / Q000494:pharmacology; D007093:Imidazoles / Q000494:pharmacology; D036341:Intercellular Signaling Peptides and Proteins / Q000096:biosynthesis*; D008222:Lymphokines / Q000096:biosynthesis*; D051379:Mice; D020928:Mitogen-Activated Protein Kinases / Q000502:physiology*; D009025:Morpholines / Q000494:pharmacology; D009570:Nitriles / Q000494:pharmacology; D010006:Osteoblasts / Q000201:enzymology*; D010766:Phosphorylation; D014176:Protein Biosynthesis; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D011506:Proteins / Q000032:analysis; D011725:Pyridines / Q000494:pharmacology; D038762:Ribosomal Protein S6 Kinases, 70-kDa / Q000378:metabolism*; D020123:Sirolimus / Q000494:pharmacology; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; D048051:p38 Mitogen-Activated Protein Kinases
D000900:Anti-Bacterial Agents; C525810:Bmp4 protein, mouse; D055415:Bone Morphogenetic Protein 4; D019485:Bone Morphogenetic Proteins; D002070:Butadienes; D002867:Chromones; D016228:Endothelial Growth Factors; D005419:Flavonoids; D007093:Imidazoles; D036341:Intercellular Signaling Peptides and Proteins; D008222:Lymphokines; D009025:Morpholines; D009570:Nitriles; D011500:Protein Synthesis Inhibitors; D011506:Proteins; D011725:Pyridines; C113580:U 0126; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; D000841:Anisomycin; D038762:Ribosomal Protein S6 Kinases, 70-kDa; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; C093642:SB 203580; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one; D020123:Sirolimus