Hanai Yoshiteru, Tokuda Haruhiko, Ishisaki Akira, Matsushima-Nishiwaki Rie, Nakamura Norimi, Yoshida Minoru, Takai Shinji, Ohta Toshiki, Kozawa Osamu
Department of Clinical Laboratory, National Hospital for Geriatric Medicine, National Center for Geriatrics and Gerontology, Obu, Aichi 474-8511, Japan.
Mol Cell Endocrinol. 2006 Jun 7;251(1-2):42-8. doi: 10.1016/j.mce.2006.02.014. Epub 2006 Apr 17.
It has been shown that insulin-like growth factor-I (IGF-I) stimulates the activity of alkaline phosphatase, a marker of mature osteoblast phenotype, in osteoblasts. In the present study, we investigated the involvement of the mitogen-activated protein (MAP) kinase superfamily in the IGF-I-stimulated alkaline phosphatase activity in osteoblast-like MC3T3-E1 cells. IGF-I-stimulated alkaline phosphatase activity dose dependently in the range between 1 nM and 0.1 microM. IGF-I induced the phosphorylation of p44/p42 MAP kinase and p38 MAP kinase but not stress-activated protein kinase/c-Jun N-terminal kinase (SAPK/JNK). PD98059 and U0126, specific inhibitors of the upstream kinase that activates p44/p42 MAP kinase, significantly suppressed the IGF-I-induced alkaline phosphatase activity. On the contrary, SB203580 and PD169316, specific inhibitors of p38 MAP kinase, failed to affect the activity induced by IGF-I. Specific inhibitors for phosphatidylinositol 3-kinase (PI3K)/Akt pathway (LY294002 and wortmannin) also had no significant effect on IGF-I-induced p44/p42 MAP kinase phosphorylation. The phosphorylation of p44/p42 MAP kinase induced by IGF-I was reduced by U0126. These results strongly suggest that p44/p42 MAP kinase among the MAP kinase superfamily plays a role in the IGF-I-stimulated alkaline phosphatase activity in osteoblast-like MC3T3-E1 cells.
研究表明，胰岛素样生长因子-I（IGF-I）可刺激成骨细胞中碱性磷酸酶的活性，碱性磷酸酶是成熟成骨细胞表型的标志物。在本研究中，我们调查了丝裂原活化蛋白（MAP）激酶超家族在IGF-I刺激的成骨样MC3T3-E1细胞碱性磷酸酶活性中的作用。IGF-I在1 nM至0.1 microM范围内剂量依赖性地刺激碱性磷酸酶活性。IGF-I诱导p44/p42 MAP激酶和p38 MAP激酶磷酸化，但不诱导应激激活蛋白激酶/c-Jun N端激酶（SAPK/JNK）磷酸化。PD98059和U0126是激活p44/p42 MAP激酶的上游激酶的特异性抑制剂，它们显著抑制了IGF-I诱导的碱性磷酸酶活性。相反，p38 MAP激酶的特异性抑制剂SB203580和PD169316未能影响IGF-I诱导的活性。磷脂酰肌醇3激酶（PI3K）/Akt途径的特异性抑制剂（LY294002和渥曼青霉素）对IGF-I诱导的p44/p42 MAP激酶磷酸化也没有显著影响。U0126降低了IGF-I诱导的p44/p42 MAP激酶磷酸化。这些结果强烈表明，MAP激酶超家族中的p44/p42 MAP激酶在IGF-I刺激的成骨样MC3T3-E1细胞碱性磷酸酶活性中起作用。
