Short-term mechanical stress inhibits osteoclastogenesis via suppression of DC-STAMP in RAW264.7 cells
Short-term mechanical stress inhibits osteoclastogenesis via suppression of DC-STAMP in RAW264.7 cells
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DOI：
10.3892/ijmm.2012.1220
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发表时间：
2013-02-01
影响因子：
5.4
通讯作者：
Iida, Junichiro
中科院分区：
文献类型：
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作者：
Kameyama, Sumika;Yoshimura, Yoshitaka;Iida, Junichiro
机械应力是骨稳态的一个重要因素，它由破骨细胞的骨吸收和成骨细胞的骨形成之间的平衡来维持。然而，机械应力对破骨细胞分化的影响知之甚少。在这项研究中，我们通过使用Flexpercell张力系统对核因子-kappa B受体激活剂(RANKL)刺激的RAW264.7细胞施加张力来研究短期机械应力对破骨细胞生成的影响。在机械应力作用或不施加机械应力作用24 h后，计数抗酒石酸酸性磷酸酶(TRAP)阳性、多核(两核或多核)的破骨细胞数，机械应力处理后破骨细胞数低于不施加机械应力处理的破骨细胞数。此外，长达24 h的机械应力导致破骨细胞特异性基因表达和融合相关分子[树突状细胞特异性跨膜蛋白(DC-STAMP)、破骨细胞刺激性跨膜蛋白(OC-STAMP)、E-钙粘素、整合素αV和整合素β3]mRNA表达下调。与对照组相比，机械应力作用24 h后DC-STAMP的蛋白表达降低，而E-钙粘素、整合素αV和整合素β3的表达略有下降。活化T细胞核因子c1(NFATc1)m RNA水平在6h降低，12h和2 4h升高。NFATc2、NFATc3基因表达水平与对照组相比无明显变化。与对照组相比，机械应激24小时显著增强NFAT转录活性，但DC-STAMP的mRNA和蛋白水平降低。这些结果表明，短期机械应力通过下调DC-STAMP和其他融合相关分子来强烈抑制破骨细胞的形成，短期机械应力诱导了一种负调控机制，取消了NFAT转录活性的增强。
Mechanical stress is an important factor in bone homeostasis, which is maintained by a balance between bone resorption by osteoclasts and bone formation by osteoblasts. However, little is known about the effects of mechanical stress on osteoclast differentiation. In this study, we examined the effects of short-term mechanical stress on osteoclastogenesis by applying tensile force to RAW264.7 cells stimulated with receptor activator of nuclear factor-kappa B ligand (RANKL) using a Flexercell tension system. We counted the number of osteoclasts that were tartrate-resistant acid phosphatase (TRAP)-positive and multinucleated (two or more nuclei) with or without application of mechanical stress for 24 h. Osteoclast number was lower after mechanical stress compared with no mechanical stress. Furthermore, mechanical stress for up to 24 h caused downregulation of osteoclast-specific gene expression and fusion-related molecule [dendritic cell specific transmembrane protein (DC-STAMP), osteoclast stimulatory transmembrane protein (OC-STAMP), E-cadherin, Integrin alpha V and Integrin beta 3] mRNA levels. Protein expression of DC-STAMP decreased with mechanical stress for 24 h compared to the control without mechanical stress, whereas the expression of E-cadherin, Integrin alpha V and Integrin beta 3 was slightly decreased. Nuclear factor of activated T cells cl (NFATcl) mRNA levels were decreased at 6 h and increased at 12 and 24 h compared with the control. The levels of NFATc2, NFATc3 mRNA did not change compared with the control group. By contrast, mechanical stress for 24 h significantly enhanced NFAT transcriptional activity compared with the control, despite a decrease in DC-STAMP mRNA and protein levels. These results suggest that short-term mechanical stress strongly inhibits osteoclastogenesis through the downregulation of DC-STAMP and other fusion-related molecules and that short-term mechanical stress induces a negative regulatory mechanism that cancels the enhancement of NFAT transcriptional activity.