Cbp recruitment of Csk into lipid rafts is critical to c-Src kinase activity and bone resorption in osteoclasts

Takuma Matsubara, Fumiyo Ikeda, Kenji Hata, Masako Nakanishi, Masato Okada, Hisataka Yasuda, Riko Nishimura, Toshiyuki Yoneda

研究成果: ジャーナルへの寄稿学術誌査読

19 被引用数 (Scopus)


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.

ジャーナルJournal of Bone and Mineral Research
出版ステータス出版済み - 5月 2010

!!!All Science Journal Classification (ASJC) codes

  • 内分泌学、糖尿病および代謝内科学
  • 整形外科およびスポーツ医学


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