STIMULATION OF MATRIX VESICLE ENZYME-ACTIVITY IN OSTEOBLAST-LIKE CELLS BY 1,25(OH)2D3 AND TRANSFORMING GROWTH-FACTOR-BETA (TGF-BETA)
STIMULATION OF MATRIX VESICLE ENZYME-ACTIVITY IN OSTEOBLAST-LIKE CELLS BY 1,25(OH)2D3 AND TRANSFORMING GROWTH-FACTOR-BETA (TGF-BETA)
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DOI：
10.1016/0169-6009(92)90725-s
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发表时间：
1992-05-01
期刊：
影响因子：
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通讯作者：
BOYAN, BD
中科院分区：
文献类型：
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作者：
BONEWALD, LF;SCHWARTZ, Z;BOYAN, BD
在证明了三种骨肉瘤细胞系MG-63、ROS 17/2.8和MC-3 T3-E1中存在基质囊泡之后，我们试图确定定位于基质囊泡的两种主要酶碱性磷酸酶和磷脂酶A2是否可以由1，25（OH）2D 3和/或TGF-β调节。囊内钙化可能依赖于这两种酶。碱性磷酸酶是水解含磷酸盐底物所必需的，磷脂酶A2在脂-水界面以钙介导的方式水解二酰基磷脂，导致膜流动性的变化和可能的基质囊泡的破裂。TGF-β还增加了两种细胞系MG-63和ROS 17/2.8中的碱性磷酸酶活性，但程度大于1，25（OH）2D 3。基质囊泡碱性磷酸酶活性比质膜中的碱性磷酸酶活性表现出更大的反应。当TGF-β与1，25（OH）2D 3结合时，1，25（OH）2D 3对磷脂酶A2没有影响，也不干扰TGF-β对磷脂酶A2活性的刺激。当1，25（OH）2D 3和TGF-β结合时，在质膜和基质囊泡中的碱性磷酸酶比活性中观察到巨大的协同作用，并靶向基质囊泡。因此，TGF-β不仅在基质形成和分化中起重要作用，而且与1，25（OH）2D 3联合作用，大大增强了单独使用1，25（OH）2D 3所观察到的效果。
After demonstrating the presence of matrix vesicles in three osteosarcoma cell lines, MG-63, ROS 17/2.8 and MC-3T3-E1, we sought to determine whether two major enzymes localized to matrix vesicles, alkaline phosphatase and phospholipase A2, could be regulated by 1,25(OH)2D3 and/or TGF-beta. Intravesicular calcification is probably dependent on these two enzymes. Alkaline phosphatase is essential for hydrolysis of phosphate-containing substrates and phospholipase A2 hydrolyzes diacylphosphatides in a calcium-mediated manner at lipid-aqueous interfaces leading to changes in membrane fluidity and possibly breakdown of the matrix vesicle.The 1,25(OH)2D3 induced increase of alkaline phosphatase in bone cells is localized to the matrix vesicle. TGF-beta also increased alkaline phosphatase activity in two of the cell lines, MG-63 and ROS 17/2.8 but to a greater degree than 1,25(OH)2D3. Matrix vesicle alkaline phosphatase activity exhibited a greater response than that in the plasma membrane. TGF-beta increased phospholipase A2 activity in both matrix vesicles and plasma membranes, therefore, no targeting was observed with respect to this enzyme.When TGF-beta was combined with 1,25(OH)2D3, 1,25(OH)2D3 had no effect on phospholipase A2 and did not interfere with TGF-beta stimulation of phospholipase A2 activity. When 1,25(OH)2D3 and TGF-beta were combined, a tremendous synergy was observed in alkaline phosphatase specific activity in both plasma membranes and matrix vesicles with targeting to matrix vesicles. Therefore, TGF-beta not only plays an important role in matrix formation and differentiation, but works in conjunction with 1,25(OH)2D3 to greatly potentiate the effects seen with 1,25(OH)2D3 alone.