Watanabe Y, Kozawa O, Suzuki A, Kotoyori J, Ito Y, Oiso Y
First Department of Internal Medicine, Nagoya University School of Medicine, Japan.
Mol Cell Endocrinol. 1994 Jul;103(1-2):115-8. doi: 10.1016/0303-7207(94)90077-9.
We previously reported that fetal calf serum-induced alkaline phosphatase activity is suppressed due to the activation of protein kinase C in osteoblast-like MC3T3-E1 cells (Miwa et al. (1991) Bone Miner. 14, 15-25; Kotoyori et al. (1994) Horm. Metab. Res. 26, 116-118). In the present study, we examined the effect of okadaic acid, a potent and specific inhibitor of protein phosphatase type 1 and 2A, on fetal calf serum-induced alkaline phosphatase activity in MC3T3-E1 cells. The pretreatment with okadaic acid enhanced the fetal calf serum-induced alkaline phosphatase activity in a dose-dependent manner in the range between 0.1 and 5 nM. 1-Norokadaone, a less potent analogue of okadaic acid, had little effect on the fetal calf serum-induced alkaline phosphatase activity. Okadaic acid partially reversed the suppression of fetal calf serum-induced alkaline phosphatase activity by 12-O-tetradecanoylphorbol-13-acetate, a protein kinase C activator. The effect of okadaic acid was dose-dependent in the range between 0.1 and 5 nM. The patterns of the dose-dependency of both okadaic acid effects on fetal calf serum-induced alkaline phosphatase activity and on the suppression by 12-O-tetradecanoylphorbol-13-acetate were similar. These results strongly suggest that protein phosphatase type 1 and/or 2A act as a regulator of alkaline phosphatase activity at a point downstream from protein kinase C in osteoblast-like cells.
我们之前报道过，在成骨样MC3T3-E1细胞中，由于蛋白激酶C的激活，胎牛血清诱导的碱性磷酸酶活性受到抑制（Miwa等人，（1991年）《骨矿物质》14卷，15 - 25页；Kotoyori等人，（1994年）《激素与代谢研究》26卷，116 - 118页）。在本研究中，我们检测了冈田酸（一种强效且特异性的蛋白磷酸酶1型和2A型抑制剂）对MC3T3-E1细胞中胎牛血清诱导的碱性磷酸酶活性的影响。用冈田酸预处理在0.1至5 nM范围内以剂量依赖方式增强了胎牛血清诱导的碱性磷酸酶活性。1-去甲冈田酮，一种活性较弱的冈田酸类似物，对胎牛血清诱导的碱性磷酸酶活性几乎没有影响。冈田酸部分逆转了蛋白激酶C激活剂12-O-十四烷酰佛波醇-13-乙酸酯对胎牛血清诱导的碱性磷酸酶活性的抑制作用。冈田酸的作用在0.1至5 nM范围内呈剂量依赖性。冈田酸对胎牛血清诱导的碱性磷酸酶活性的影响以及对12-O-十四烷酰佛波醇-13-乙酸酯抑制作用的剂量依赖性模式相似。这些结果强烈表明，在成骨样细胞中，蛋白磷酸酶1型和/或2A型在蛋白激酶C下游的某个点作为碱性磷酸酶活性的调节剂发挥作用。
