Cbp Recruitment of Csk into Lipid Rafts Is Critical to c-Src Kinase Activity and Bone Resorption in Osteoclasts
Cbp Recruitment of Csk into Lipid Rafts Is Critical to c-Src Kinase Activity and Bone Resorption in Osteoclasts
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DOI：
10.1359/jbmr.091039
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发表时间：
2010-05-01
影响因子：
6.2
通讯作者：
Yoneda, Toshiyuki
中科院分区：
文献类型：
--
作者：
Matsubara, Takuma;Ikeda, Fumiyo;Yoneda, Toshiyuki
酪氨酸激酶 c-Src 在皱褶边界形成和骨吸收中发挥着不可或缺的作用，在破骨细胞中具有组成型活性。然而，迄今为止，破骨细胞中 c-Src 活性增加的分子机制尚不清楚。为了解决这个问题，我们首先检查了 Csk（c-Src 的负调节激酶）的表达水平和亚细胞定位。我们发现破骨细胞中Csk的表达水平与其他组织相当。然而，在破骨细胞中，Csk 几乎不定位于脂筏中，而 c-Src 在脂筏中高度表达。有趣的是，与其他组织相比，破骨细胞中 Cbp 的表达非常低，Cbp 通过与 Csk 的物理相互作用将 Csk 招募到脂筏中。为了了解 Cbp 在破骨细胞中的重要性，我们使用腺病毒基因传递系统将 Cbp 引入破骨细胞中。 Cbp 的引入刺激 Csk 募集到脂筏中，并以剂量依赖性方式抑制 c-Src 活性。此外，Cbp 的引入显着抑制了破骨细胞中肌动蛋白环的形成和骨吸收活性。此外，RANKL 处理和 TRAF6 或 NFAT2 过表达抑制破骨细胞系 RAW264.7 中的 Cbp 表达以及破骨细胞分化。 NFAT2 过表达还抑制脾巨噬细胞中 Cbp 的表达。总的来说，我们的结果表明 Cbp 表达的减少是破骨细胞中维持高 c-Src 活性的原因。这些发现有助于了解破骨细胞中 c-Src 的独特调节系统。 (C) 2010 年美国骨与矿物质研究学会。
A tyrosine kinase, c-Src, that plays an indispensable role in ruffled border formation and bone resorption is constitutively active in osteoclasts. However, to date, the molecular mechanism underlying increased c-Src activity in osteoclasts is unknown. To address this, we first examined the expression levels and subcellular localization of Csk, a negative regulatory kinase for c-Src. We found that the expression level of Csk in osteoclasts was comparable with that of other tissues. However, in osteoclasts, Csk was hardly localized in lipid rafts, where c-Src is highly expressed. Interestingly, expression of Cbp, which recruits Csk into lipid rafts through physical interaction with Csk, was very low in osteoclasts compared with other tissues. To understand the importance of Cbp in osteoclasts, we introduced Cbp into osteoclasts using an adenovirus gene delivery system. Introduction of Cbp stimulated recruitment of Csk into lipid rafts and suppressed c-Src activity in a dose-dependent manner. Furthermore, introduction of Cbp markedly inhibited formation of actin rings and bone-resorbing activity in osteoclasts. In addition, treatment with RANKL and overexpression of TRAF6 or NFAT2 inhibited Cbp expression in the osteoclastogenic cell line RAW264.7 along with osteoclastic differentiation. NFAT2 overexpression also inhibited Cbp expression in spleen macrophages. Collectively, our results indicate that reduction in Cbp expression is responsible for maintaining high c-Src activity in osteoclasts. These findings contribute to an understanding of the unique regulatory system for c-Src in osteoclasts. (C) 2010 American Society for Bone and Mineral Research.