Yano Masato, Kawao Naoyuki, Okumoto Katsumi, Tamura Yukinori, Okada Kiyotaka, Kaji Hiroshi
From the Department of Physiology and Regenerative Medicine, Kinki University Faculty of Medicine, 377-2, Ohnohigashi, Osakasayama 589-8511 and.
the Life Science Research Institute, Kinki University, 377-2, Ohnohigashi, Osakasayama 589-8511, Japan.
J Biol Chem. 2014 Jun 13;289(24):16966-77. doi: 10.1074/jbc.M113.526038. Epub 2014 May 5.
Fibrodysplasia ossificans progressiva is characterized by extensive ossification within muscle tissues, and its molecular pathogenesis is responsible for the constitutively activating mutation (R206H) of the bone morphogenetic protein type 1 receptor, activin-like kinase 2 (ALK2). In this study, we investigated the effects of implanting ALK2 (R206H)-transfected myoblastic C2C12 cells into nude mice on osteoclast formation during heterotopic ossification in muscle and subcutaneous tissues. The implantation of ALK2 (R206H)-transfected C2C12 cells with BMP-2 in nude mice induced robust heterotopic ossification with an increase in the formation of osteoclasts in muscle tissues but not in subcutaneous tissues. The implantation of ALK2 (R206H)-transfected C2C12 cells in muscle induced heterotopic ossification more effectively than that of empty vector-transfected cells. A co-culture of ALK2 (R206H)-transfected C2C12 cells as well as the conditioned medium from ALK2 (R206H)-transfected C2C12 cells enhanced osteoclast formation in Raw264.7 cells more effectively than those with empty vector-transfected cells. The transfection of ALK2 (R206H) into C2C12 cells elevated the expression of transforming growth factor (TGF)-β, whereas the inhibition of TGF-β signaling suppressed the enhanced formation of osteoclasts in the co-culture with ALK2 (R206H)-transfected C2C12 cells and their conditioned medium. In conclusion, this study demonstrated that the causal mutation transfection of fibrodysplasia ossificans progressiva in myoblasts enhanced the formation of osteoclasts from its precursor through TGF-β in muscle tissues.
进行性骨化性纤维发育不良的特征是肌肉组织内广泛骨化，其分子发病机制是骨形态发生蛋白1型受体（激活素样激酶2，ALK2）的组成性激活突变（R206H）。在本研究中，我们研究了将ALK2（R206H）转染的成肌C2C12细胞植入裸鼠体内对肌肉和皮下组织异位骨化过程中破骨细胞形成的影响。将ALK2（R206H）转染的C2C12细胞与BMP-2一起植入裸鼠体内，可诱导强烈的异位骨化，肌肉组织中破骨细胞形成增加，但皮下组织中未增加。将ALK2（R206H）转染的C2C12细胞植入肌肉比空载体转染的细胞更有效地诱导异位骨化。ALK2（R206H）转染的C2C12细胞以及ALK2（R206H）转染的C2C12细胞的条件培养基共培养，比空载体转染的细胞更有效地增强了Raw264.7细胞中的破骨细胞形成。将ALK2（R206H）转染到C2C12细胞中可提高转化生长因子（TGF）-β的表达，而抑制TGF-β信号可抑制与ALK2（R206H）转染的C2C12细胞及其条件培养基共培养时破骨细胞形成的增强。总之，本研究表明，成肌细胞中进行性骨化性纤维发育不良的致病突变转染通过TGF-β增强了肌肉组织中破骨细胞前体的破骨细胞形成。
