Nakamura H, Ozawa H
First Department of Oral Anatomy, Niigata University School of Dentistry, Japan.
J Bone Miner Res. 1996 Nov;11(11):1715-22. doi: 10.1002/jbmr.5650111115.
We studied the immunohistochemical localization of CD44, hyaluronate receptor, and the ezrin-radixin-moesin (ERM) family, actin binding proteins, in bone cells using confocal laser scanning microscopy and transmission electron microscopy to clarify the mechanism of the organization of their cytoskeletons. In osteoclasts, intense immunoreactivity to CD44 could be detected on their basolateral plasma membranes. There was less reactivity observed in the area of the plasma membrane in direct contact with the bone surface. The immunogold electron-microscopical method revealed that CD44 was mainly localized on the microvilli of the basolateral plasma membrane. The plasma membrane of the clear zone and the ruffled border were not immunolabeled with CD44. As for the ERM family, the basolateral plasma membrane of osteoclasts was stained with antimoesin monoclonal antibody, but not with ezrin or radixin. In osteoblasts attached to the bone surface, immunoreactivity to CD44 was restricted to their cytoplasmic processes. They showed immunoreactivities to radixin and moesin on the cytoplasmic side of their plasma membrane when in contact with each other. However, although osteocytes in the bone matrix demonstrate an intense immunolabeling with CD44 on their plasma membrane, they scarcely show immunoreactivity to the ERM family. These findings suggest that: (1) the CD44-moesin-actin filament system is involved in the organization of cytoskeletons in the basolateral plasma membrane of osteoclasts; and (2) other mechanisms, rather than the CD44 and the ERM family, may be involved in the cells of osteoblast lineage.
我们利用共聚焦激光扫描显微镜和透射电子显微镜研究了骨细胞中CD44（透明质酸受体）和埃兹蛋白-根蛋白-膜突蛋白（ERM）家族（肌动蛋白结合蛋白）的免疫组织化学定位，以阐明其细胞骨架的组织机制。在破骨细胞中，可在其基底外侧质膜上检测到对CD44的强烈免疫反应性。在与骨表面直接接触的质膜区域观察到的反应性较低。免疫金电子显微镜方法显示，CD44主要定位于基底外侧质膜的微绒毛上。透明区和皱褶缘的质膜未被CD44免疫标记。至于ERM家族，破骨细胞的基底外侧质膜用抗膜突蛋白单克隆抗体染色，但未用埃兹蛋白或根蛋白染色。在附着于骨表面的成骨细胞中，对CD44的免疫反应性仅限于其细胞质突起。当它们相互接触时，在其质膜的细胞质侧显示出对根蛋白和膜突蛋白的免疫反应性。然而，尽管骨基质中的骨细胞在其质膜上显示出对CD44的强烈免疫标记，但它们几乎不显示对ERM家族的免疫反应性。这些发现表明：（1）CD44-膜突蛋白-肌动蛋白丝系统参与破骨细胞基底外侧质膜细胞骨架的组织；（2）成骨细胞系细胞可能涉及其他机制，而非CD44和ERM家族。
