Osteoblast lineage-specific cell-surface antigen (A7) regulates osteoclast recruitment and calcification during bone remodeling
Osteoblast lineage-specific cell-surface antigen (A7) regulates osteoclast recruitment and calcification during bone remodeling
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DOI：
10.1038/s41374-018-0179-4
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发表时间：
2019-06-01
影响因子：
5
通讯作者：
Kukita, Toshio
中科院分区：
文献类型：
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作者：
Badawy, Tamer;Kyumoto-Nakamura, Yukari;Kukita, Toshio
骨重建是一个连续的过程，其特征在于在不同的多细胞单位中高度协调的细胞-细胞相互作用。破骨细胞是一种特殊的骨吸收细胞，在骨重建中起着重要作用。尽管RANKL/RANK轴决定了骨组织中存在的破骨细胞总数，但与破骨细胞募集、骨重建启动以及骨吸收和骨形成偶联相关的调节骨重建的详细分子事件仍不明确。我们假设成骨细胞特异性的细胞表面分子有助于骨重建的分子调节。因此，我们通过B细胞杂交瘤技术寻找成骨细胞表面表达的调控分子。我们获得了对成骨细胞系具有高度特异性的单克隆抗体A7（A7 MAb）。在这里，我们描述的表达模式和A7单抗特异性识别A7抗原的可能作用。体外培养的成骨细胞和成骨样骨髓基质细胞表面均表达A7抗原。在体内，A7抗原在骨表面成骨细胞和骨细胞的一个子集中检测到，具有典型的细胞膜表达模式。组织芯片分析显示，只有有限的A7抗原表达在骨细胞接近骨表面。免疫印迹和免疫沉淀分析表明，A7抗原是一种谱系特异性细胞表面蛋白，分子量约为45 KDa。破骨细胞生成培养物中细胞表面A7抗原的交联显示破骨细胞形成的刺激。当A7抗原与抗A7抗原单克隆抗体A7单克隆抗体交联时，观察到原代成骨细胞培养物中钙化的显著抑制。这些数据表明，A7抗原调节破骨细胞的募集和钙化的触发。A7抗原可能是参与精确调节骨重建的重要分子。
Bone remodeling is a continuous process characterized by highly coordinated cell-cell interactions in distinct multi-cellular units. Osteoclasts, which are specialized bone resorbing cells, play a central role in bone remodeling. Although the RANKL/RANK axis determines the gross number of osteoclasts present in bone tissue, detailed molecular events regulating bone remodeling related to osteoclast recruitment, initiation of bone remodeling, and coupling of bone resorption and bone formation are still ambiguous. We hypothesized that osteoblast-specific cell-surface molecules contribute to the molecular modulation of bone remodeling. Therefore, we searched for regulatory cell-surface molecules expressed on osteoblasts by use of B-cell hybridoma technology. We obtained a monoclonal antibody A7 (A7 MAb) highly specific to cells of osteoblast-lineage. Here we describe the expression pattern and possible role of A7 antigen specifically recognized by A7 MAb. In vitro, A7 antigen was expressed on cell-surface of osteoblasts and osteoblast-like bone marrow stromal cells. In vivo, A7 antigen was detected in a subset of bone surface osteoblasts and in osteocytes, with a typical cell membrane expression pattern. Tissue array analysis showed only a limited expression of A7 antigen in osteocytes close to the bone surface. Immunoblotting and immunoprecipitation analysis showed that A7 antigen is a lineage-specific cell-surface protein with an approximate molecular weight of 45 KDa. Cross-linking of cell-surface A7 antigen in cultures of osteoclastogenesis showed stimulation of osteoclast formation. Marked suppression of calcification in primary osteoblast cultures was observed when A7 antigen was cross-linked with anti-A7 antigen MAb, A7 MAb. These data suggest that A7 antigen regulates recruitment of osteoclasts and triggering of calcification. A7 antigen may be an important molecule involved in the precise regulation of bone remodeling.