ITAMモチーフによって媒介されるコストシグナルが,骨の恒常性のためにRANKLと協力する
Takako Koga1, Masanori Inui, Kazuya Inoue
1Department of Immunology, Graduate School of Medicine and Faculty of Medicine, University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan.
Nature
|April 16, 2004
まとめ
免疫系アダプターであるFc受容体共通ガンマサブユニット (FcRgamma) とDNAX活性化タンパク質 (DAP) 12は,骨の健康に極めて重要です. 欠乏すると,骨格細胞の分化が損なわれ,骨格の恒常性を維持する上で重要な役割が強調される.
科学分野:
- 免疫学 免疫学とは
- 骨格生物学 骨格生物学とは
- 細胞シグナル伝達 細胞信号伝達
背景:
- コスシミュレータ信号は免疫細胞の活性化に不可欠ですが,骨格の発達などの他の生物系における役割はあまり理解されていません.
- 骨格のホメオスタシスは,骨の形成と再吸収のバランスに依存し,受容体活性化剤のNF-kappaBリンガンド (RANKL) が骨格細胞の分化を調節します.
研究 の 目的:
- 骨格生物学における免疫受容体チロシンベースの活性化モチーフ (ITAM) - ハーバリングアダプターの役割を調査する.
- RANKLとM-CSFの刺激を超えて,骨格結晶形成に関与するシグナル伝達経路を解明する.
主な方法:
- Fc受容体共通ガンマサブユニット (FcRgamma) とDNAX活性化タンパク質 (DAP) が欠けているマウスの分析12.
- オステオクラスト前駆細胞におけるカルシウムシグナル伝達活性化の調査.
- オステオクラストの分化と骨の恒常性の評価.
主要な成果:
- FcRgammaとDAP12が欠けていたマウスは,骨格細胞の分化障害による重度の骨粗鬆症を発症した.
- FcRgammaとDAP12は,免疫受容体と結合し,骨格細胞の前駆体におけるCgammaフォスフォリファース経由でカルシウムシグナル伝達を活性化することが判明しました.
- これらの発見は,RANKLとM-CSFだけでは,骨格結晶形成のシグナル伝達には不十分であることを示している.
結論:
- FcRgammaとDAP12によって媒介されるITAM依存の共刺激信号は,骨のホメオスタシスにとって不可欠である.
- 多数の免疫受容体は,ITAMに依存するシグナル伝達経路を通じて,骨格の維持に貢献します.
- この研究は,これまで知られている経路とは独立して,骨格生物学における共刺激信号の新たな役割を明らかにしています.
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