Regulation of RANKL‐induced osteoclastogenesis by TGF‐β through molecular interaction between Smad3 and Traf6
Regulation of RANKL‐induced osteoclastogenesis by TGF‐β through molecular interaction between Smad3 and Traf6
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DOI：
10.1002/jbmr.357
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发表时间：
2011-07
影响因子：
6.2
通讯作者：
T. Yasui;Y. Kadono;Masaki Nakamura;Y. Oshima;Takumi Matsumoto;Hironari Masuda;J. Hirose;Y. Omata;H. Yasuda;T. Imamura;Kozo Nakamura;Sakae Tanaka
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文献类型：
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作者：
T. Yasui;Y. Kadono;Masaki Nakamura;Y. Oshima;Takumi Matsumoto;Hironari Masuda;J. Hirose;Y. Omata;H. Yasuda;T. Imamura;Kozo Nakamura;Sakae Tanaka
既往研究表明，转化生长因子β（TGF-β）促进核因子κB配体受体激活剂（RANKL）诱导的破骨细胞生成。然而，潜在的分子机制尚未阐明。当TGF-β信号被TGF-β 1型受体激酶活性的特异性抑制剂SB 431542或通过引入TGF-β 2型受体的显性负突变体阻断时，RANKL诱导的破骨细胞生成几乎完全被抑制。通过过表达Smad 7或c-Ski阻断Smad信号传导可显著抑制RANKL诱导的破骨细胞生成，逆转录病毒诱导Smad 2或Smad 3的活化突变体可逆转SB 431542的抑制作用。免疫沉淀分析显示，Smad 2/3直接与TRAF 6-TAB 1-TAK 1分子复合物结合，该分子复合物是在RANKL刺激下产生的，在破骨细胞分化中起重要作用。当TGF-β信号传导被阻断时，未观察到TRAF 6-TAB 1-TAK 1复合物形成。使用缺失突变体的分析显示，Smad 3的MH 2结构域对于TRAF 6-TAB 1-TAK 1复合物形成、下游信号转导和破骨细胞形成是必需的。此外，破骨细胞前体中Smad 3的基因沉默显著抑制RANKL诱导的破骨细胞分化。总之，TGF-β在RANKL诱导的破骨细胞生成中不可或缺，Smad 3与TRAF 6-TAB 1-TAK 1复合物的结合对于RANKL诱导的破骨细胞生成信号传导至关重要。© 2011美国骨与矿物质研究学会。
Previous studies have shown that transforming growth factor β (TGF‐β) promotes receptor activator of nuclear factor‐κB ligand (RANKL)–induced osteoclastogenesis. However, the underlying molecular mechanisms have not been elucidated. When TGF‐β signals were blocked either by a specific inhibitor of TGF‐β type 1 receptor kinase activity, SB431542, or by introducing a dominant‐negative mutant of TGF‐β type 2 receptor, RANKL‐induced osteoclastogenesis was almost completely suppressed. Blockade of Smad signaling by overexpression of Smad7 or c‐Ski markedly suppressed RANKL‐induced osteoclastogenesis, and retroviral induction of an activated mutant of Smad2 or Smad3 reversed the inhibitory effect of SB431542. Immunoprecipitation analysis revealed that Smad2/3 directly associates with the TRAF6‐TAB1‐TAK1 molecular complex, which is generated in response to RANKL stimulation and plays an essential role in osteoclast differentiation. TRAF6‐TAB1‐TAK1 complex formation was not observed when TGF‐β signaling was blocked. Analysis using deletion mutants revealed that the MH2 domain of Smad3 is necessary for TRAF6‐TAB1‐TAK1 complex formation, downstream signal transduction, and osteoclast formation. In addition, gene silencing of Smad3 in osteoclast precursors markedly suppressed RANKL‐induced osteoclast differentiation. In summary, TGF‐β is indispensable in RANKL‐induced osteoclastogenesis, and the binding of Smad3 to the TRAF6‐TAB1‐TAK1 complex is crucial for RANKL‐induced osteoclastogenic signaling. © 2011 American Society for Bone and Mineral Research.