膜性化骨部位の Lactate dehydrogenase 含有基質小胞様顆粒に関する研究

概要

論文の詳細を見る
Matrix vesicles are membrane-enclosed structures that initiate mineralization in the extracellular matrix of calcifying tissues. Matrix vesicles in mineralizing tissues contain alkaline phosphatase and related phosphatase activities associated with the plasma membrane ; this may be because matrix vesicles may be the extracellular cell-membrane derived microstructures. Recently, lactate dehydrogenase isoenzymes were found to be located in matrix vesicles of the epiphyseal growth plate of young rabbit leg bones [Hosokawa et al. (1988) J. Biol. Chem. 263, 10045-10047]. In addition, lactate dehydrogenase-containing vesicles without alkaline phosphatase were found in the resting zone of the epiphyseal cartilage of young rat rib bones [Ohashi-Takeuchi et al. (1990) Biochem. J. 266, 309-312], and in the dentin of bovine tooth germs [Kitamura et al. (1991) J. Dent. Res. 70 : 1444-1446]. However, there is no report on the presence of lactate dehydrogenase-containing vesicles in the area in which intramembranous bone formation occurs. In the present study, lactate dehydrogenase-containing vesicles were found to be present in calvaria of mice and calves in which intramembranous bone formation occurs, as follows. 1. Only in the presence of detergents, lactate dehydrogenase activity was detected in the matrix vesicle fraction from the calvaria of young mice, showing that lactate dehydrogenase is located in the vesicles. 2. The matrix vesicle fraction was subjected to sucrose density gradient centrifugation. The sedimentation profiles of lactate dehydrogenase in the presence of Triton X-100 were different from that of alkaline phosphatase, showing that lactate dehydrogenase-containing vesicles were different from matrix vesicles. 3. Osteoblast fraction from mice calvaria was homogenized with isotonic solution and then subjected to sucrose density gradient centrifugation. Lactate dehydrogenase activity was recovered only in the soluble top fraction, but not in sediment, showing that lactate dehydrogenase is located only in the cytosol of osteoblasts. The result shows that lactate dehydrogenase in the vesicles is not simply encapsulated by vesicles from the plasma membranes or membranes of intracellular organelles. 4. Electrophoretic profiles of lactate dehydrogenase isoenzymes from matrix vesicle fraction of mice calvaria were identical with those of cytosolic lactate dehydrogenase of mice calvaria osteoblasts, suggesting that the presence of a mechanism for the specific uptake of cytosolic lactate dehydrogenase into vesicles. 5. Lactate dehydrogenase-containing vesicles were found to be also present in fetal calf calvaria.
1992-02-25

膜性化骨部位の Lactate dehydrogenase 含有基質小胞様顆粒に関する研究

スポンサーリンク

概要

著者

関連論文

スポンサーリンク