Tokuda Haruhiko, Hatakeyama Daijiro, Akamatsu Shigeru, Tanabe Kumiko, Yoshida Minoru, Shibata Toshiyuki, Kozawa Osamu
Department of Internal Medicine, Chubu National Hospital, National Institute for Longevity Sciences, Obu, Aichi 474-8511, Japan.
Arch Biochem Biophys. 2003 Jul 1;415(1):117-25. doi: 10.1016/s0003-9861(03)00225-x.
Transforming growth factor-beta (TGF-beta) reportedly induces vascular endothelial growth factor (VEGF) synthesis in osteoblast-like MC3T3-E1 cells. We have recently shown that TGF-beta activates p44/p42 mitogen-activated protein (MAP) kinase and p38 MAP kinase in these cells. In the present study, we investigated the exact mechanism of TGF-beta behind the synthesis of VEGF in MC3T3-E1 cells. PD98059 and U-0126, specific inhibitors of MEK, suppressed the VEGF synthesis induced by TGF-beta. U-0126 inhibited the TGF-beta-induced p44/p42 MAP kinase phosphorylation. SB203580 and PD169316, inhibitors of p38 MAP kinase, reduced the TGF-beta-stimulated VEGF synthesis. SB202474, a negative control for p38 MAP kinase inhibitor, did not affect the VEGF synthesis. A combination with PD98059 and SB203580 almost completely suppressed the TGF-beta-induced VEGF synthesis. Retinoic acid, which alone failed to affect VEGF synthesis, markedly enhanced the VEGF synthesis stimulated by TGF-beta. Retinoic acid enhanced the TGF-beta-increased levels of VEGF mRNA. The amplifications by retinoic acid of TGF-beta-increased VEGF synthesis and levels of VEGF mRNA were reduced by PD98059 or SB203580. The combination of PD98059 and SB203580 almost completely suppressed the enhancement by retinoic acid of VEGF synthesis induced by TGF-beta. Taken together, our results strongly suggest that both p44/p42 MAP kinase and p38 MAP kinase take part in TGF-beta-stimulated VEGF synthesis in osteoblasts, and that retinoic acid upregulates the VEGF synthesis.
据报道，转化生长因子-β（TGF-β）可诱导成骨样MC3T3-E1细胞中血管内皮生长因子（VEGF）的合成。我们最近发现，TGF-β可激活这些细胞中的p44/p42丝裂原活化蛋白（MAP）激酶和p38 MAP激酶。在本研究中，我们探究了TGF-β在MC3T3-E1细胞中合成VEGF背后的确切机制。MEK的特异性抑制剂PD98059和U-0126可抑制TGF-β诱导的VEGF合成。U-0126可抑制TGF-β诱导的p44/p42 MAP激酶磷酸化。p38 MAP激酶抑制剂SB203580和PD169316可降低TGF-β刺激的VEGF合成。p38 MAP激酶抑制剂的阴性对照SB202474对VEGF合成无影响。PD98059和SB203580联合使用几乎完全抑制了TGF-β诱导的VEGF合成。单独使用时对VEGF合成无影响的视黄酸，可显著增强TGF-β刺激的VEGF合成。视黄酸可提高TGF-β升高的VEGF mRNA水平。PD98059或SB203580可降低视黄酸对TGF-β升高的VEGF合成和VEGF mRNA水平的放大作用。PD98059和SB203580联合使用几乎完全抑制了视黄酸对TGF-β诱导的VEGF合成的增强作用。综上所述，我们的结果强烈表明，p44/p42 MAP激酶和p38 MAP激酶均参与TGF-β刺激的成骨细胞中VEGF的合成，且视黄酸可上调VEGF的合成。
