Journal of Bone and Mineral Metabolism

, Volume 29, Issue 3, pp 291–299

Regulation of Tcf7 by Runx2 in chondrocyte maturation and proliferation

  • Masaki Mikasa
  • Satoshi Rokutanda
  • Hisato Komori
  • Kosei Ito
  • Ying Sze Tsang
  • Yuki Date
  • Carolina A. Yoshida
  • Toshihisa Komori
Original Article

DOI: 10.1007/s00774-010-0222-z

Cite this article as:
Mikasa, M., Rokutanda, S., Komori, H. et al. J Bone Miner Metab (2011) 29: 291. doi:10.1007/s00774-010-0222-z

Abstract

Runx2 plays important roles in the regulation of chondrocyte differentiation and proliferation; however, the Runx2 target molecules still remain to be investigated. We searched the genes upregulated by the introduction of Runx2 into Runx2−/− chondrocytes using microarray and found that Tcf7 is upregulated by Runx2. Thus, we examined the functions of Runx2 in the regulation of the Tcf/Lef family of transcription factors. Runx2 induced Tcf7 and Lef1 strongly, but Tcf7l1 and Tcf7l2 only slightly in Runx2−/− chondrocytes; the expressions of Tcf7and Tcf7l2 were reduced in Runx2−/− cartilaginous skeletons and calvaria, and Tcf7 showed a similar expression pattern to Runx2. In reporter assays, Runx2 mildly activated the 8.6 and 1.8 kb Tcf7 promoter constructs. The reporter assays using the deletion constructs of the 1.8-kb fragment showed that the 0.3-kb promoter region is responsible for the Runx2-dependent transcriptional activation. To investigate the function of Tcf7 in skeletal development, we generated dominant-negative (dn) Tcf7 transgenic mice using the Col2a1 promoter. Dn-Tcf7 transgenic embryos showed dwarfism, and mineralization was retarded in limbs, ribs, and vertebrae in a manner dependent on the expression levels of the transgene. In situ hybridization analysis showed that endochondral ossification is retarded in dn-Tcf7 transgenic embryos due to the decelerated chondrocyte maturation. Further, BrdU labeling showed a reduction in chondrocyte proliferation in the proliferating layer of the growth plate in dn-Tcf7 transgenic embryos. These findings indicate that Runx2 regulates chondrocyte maturation and proliferation at least partly through the induction of Tcf7.

Keywords

Runx2Tcf7Lef1Chondrocyte differentiationChondrocyte proliferation

Copyright information

© The Japanese Society for Bone and Mineral Research and Springer 2010

Authors and Affiliations

  • Masaki Mikasa
    • 1
  • Satoshi Rokutanda
    • 1
    • 2
  • Hisato Komori
    • 1
  • Kosei Ito
    • 1
  • Ying Sze Tsang
    • 1
  • Yuki Date
    • 1
  • Carolina A. Yoshida
    • 1
  • Toshihisa Komori
    • 1
  1. 1.Department of Cell Biology, Unit of Basic Medical SciencesNagasaki University Graduate School of Biomedical SciencesNagasakiJapan
  2. 2.Department of Oral and Maxillofacial Surgery, Unit of Translational MedicineNagasaki University Graduate School of Biomedical SciencesNagasakiJapan