Background: When C2C12 pluripotent mesenchymal precursor cells are treated with transforming growth factor-β1 (TGF-β1), terminal differentiation into myotubes is blocked. Treatment with bone morphogenetic protein-2 (BMP-2) not only blocks myogenic differentiation but also induces osteoblastic differentiation. However, the molecular mechanisms governing the ability of TGF-β and BMP to induce ligand-specific responses and inhibit myogenic differentiation are not known. The objective of our studies was to elucidate the molecular mechanisms that block myoblastic differentiation and induce osteoblastic differentiation in C2C12 cells.
Methods: Induction of RUNX2/PEBP2αA/Cbfa1 by TGF-β and BMP was examined by electrophoretic mobility shift assay (EMSA) and Northern blot analysis. C2C12 cells stably expressing RUNX2 or Smad, or both, were established, and the role of these genes in the process of osteoblastic differentiation was analyzed by examining the expression of osteoblast-specific markers.
Results: Treatment of C2C12 with TGF-β and BMP-induced RUNX2/PEBP2αA/Cbfa1, a global regulator of osteogenesis. Cooperation between RUNX2 and BMP-activated Smad induced osteoblastic differentiation.
Conclusions: Both TGF-β and BMP activate transcription of RUNX2, which is sufficient to inhibit myogenesis. To induce osteogenesis, BMP-induced RUNX2 must cooperate with BMP-activated Smads.
Investigation performed at the Department of Biochemistry, School of Medicine, and Medical Research Institute, Chungbuk National University, Cheongju, Korea; and the Department of Viral Oncology, Institute for Virus Research, Kyoto University, Kyoto, Japan
In support of their research or preparation of this manuscript, one or more of the authors received grants or outside funding from Basic Research Program of the Korea Science and Engineering Foundation and Grant-in-Aid 09253220 for Priority Area in Cancer Research from the Ministry of Education, Science, Sports and Culture, Japan. None of the authors received payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity. No commercial entity paid or directed, or agreed to pay or direct, any benefits to any research fund, foundation, educational institution, or other charitable or nonprofit organization with which the authors are affiliated or associated.
- Copyright © 2001 by The Journal of Bone and Joint Surgery, Incorporated
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