A role of cPLA_2 in the process when extraction socket is repaired.

骨细胞被认为是修复拔牙槽所必需的。据报道，代谢产物PGE2对破骨功能有负调控作用。然而，目前尚不清楚cPLA_2本身是否参与破骨细胞活性的调节。在这项研究中，我们测试了cPLA_2活性对破骨细胞形成的可能性。我们进一步研究了cPLA_2在破骨细胞和肌细胞多核细胞形成过程中的细胞融合机制，以及多核细胞形成开始后cPLA_2和肌动蛋白亚细胞分布的变化。用激光共聚焦扫描显微镜分析cPLA_2和actin的亚细胞定位。未处理RAW264.7细胞cPLA_2和肌动蛋白分布在细胞质中。然而，这些蛋白主要分布在rankl处理的RAW264.7细胞的周围。cPLA_2抑制对多核细胞形成的影响。接下来，我们通过特异性cPLA_2、抑制剂或cPLA_2 siRNA来评估cPLA_2在rankl处理RAW264.7细胞的多核细胞形成和骨吸收能力调节中的作用。我们发现cPLA_2抑制剂（AACOCF3和MAFP）或cPLA_2 siRNA显著抑制RAW264.7细胞的多核细胞形成和体外骨吸收能力。cPLA_2参与C2C12细胞的多核肌细胞形成。我们发现C2C12多核肌细胞的形成也被cPLA_2抑制剂或RNA干扰所抑制。综上所述，这些结果表明cPLA_2可能深入参与破骨细胞的发生和肌肉的发生。上述部分结果在第47届日本口腔颌面放射学会大会（2006年5月，东京）上报道。

Osteocasts are believed necessary for the repair of extraction socket.A cPLA_2, metabolite PGE2 has been repoted to be negative regulation of osteoclastic function. However, it is not still uncertain whether cPLA_2 per se is involved in the regulation of osteoclastic activity. In this study, we tested the possibility that cPLA_2 activity is necessary for osteoclastogenesis. Further, we investigated the role of cPLA_2 in the cell-fusion mechanism in multinucleated cell formation of osteoclasts and myocytesChanges in subcellular distributions of cPLA_2 and actin after initiation of multinucleated cell formation.Subcellular localizations of cPLA_2 and actin were analyzed by using a confocal laser scanning microscope. The cPLA_2 and actin were distributed throughout the cytoplasm of non-treated RAW264.7 cells. However, there proteins were predominantly distributed at the periphery of the RANKL-treated RAW264.7 cells.Effects of cPLA_2 inhibition in multinucleated cell formation.Next, we assessed the role of cPLA_2 in the multinucleated cell formation and in the regulation of bone resorption ability of RANKL-treated RAW264.7 cells by using the specific cPLA_2, inhibitors or the cPLA_2 siRNA. We found that the cPLA_2 inhibitors (AACOCF3 and MAFP) or cPLA_2 siRNA significantly inhibited multinucleated cell formation and in vitro bone resorption ability of RAW264.7 cells.cPLA_2 involvement in multinucleated myocyte formation of C2C12 cells.We found that multinucleated myocyte formation in C2C12 was also inhibited by the cPLA_2 inhibitors or RNA interference.Together, these results suggest that cPLA_2 may be deeply involved in osteoclastogenesis and myogenesis. A part of the above results was reported at the 47th Congress on Japanese Society for Oral and Maxillofacial Radiology (May, 2006, Tokyo).