Tcf12, A Member of Basic Helix-Loop-Helix Transcription Factors, Mediates Bone Marrow Mesenchymal Stem Cell Osteogenic Differentiation In Vitro and In Vivo

Stem Cells. 2017 Feb;35(2):386-397. doi: 10.1002/stem.2491. Epub 2016 Sep 27.


Several basic Helix-Loop-Helix transcription factors have recently been identified to regulate mesenchymal stem cell (MSC) differentiation. In the present study, Tcf12 was investigated for its involvement in the osteoblastic cell commitment of MSCs. Tcf12 was found highly expressed in undifferentiated MSCs whereas its expression decreased following osteogenic culture differentiation. Interestingly, Tcf12 endogenous silencing using shRNA lentivirus significantly promoted the differentiation ability of MSCs evaluated by alkaline phosphatase staining, alizarin red staining and expression of osteoblast-specific markers by real-time PCR. Conversely, overexpression of Tcf12 in MSCs suppressed osteoblast differentiation. It was further found that silencing of Tcf12 activated bone morphogenetic protein (BMP) signaling and extracellular signal-regulated kinase (Erk)1/2 signaling pathway activity and upregulated the expression of phospho-SMAD1 and phospho-Erk1/2. A BMP inhibitor (LDN-193189) and Erk1/2 signaling pathway inhibitor (U0126) reduced these findings in the Tcf12 silencing group. Following these in vitro results, a poly-L-lactic acid/Hydroxyappatite scaffold carrying Tcf12 silencing lentivirus was utilized to investigate the repair of bone defects in vivo. The use of Tcf12 silencing lentivirus significantly promoted new bone formation in 3-mm mouse calvarial defects as assessed by micro-CT and histological examination whereas overexpression of Tcf12 inhibited new bone formation. Collectively, these data indicate that Tcf12 is a transcription factor highly expressed in the nuclei of stem cells and its downregulation plays an essential role in osteoblast differentiation partially via BMP and Erk1/2 signaling pathways. Stem Cells 2017;35:386-397.

Keywords: Bone mesenchymal stem cells; Bone morphogenetic protein signaling; Bone regeneration; Extracellular signal-regulated kinase 1/2 signaling; Osteogenesis; Tcf12.

MeSH terms

  • Animals
  • Basic Helix-Loop-Helix Transcription Factors / genetics
  • Basic Helix-Loop-Helix Transcription Factors / metabolism*
  • Bone Marrow Cells / cytology*
  • Bone Morphogenetic Proteins / metabolism
  • Bone and Bones / pathology
  • Cell Differentiation* / genetics
  • Cell Line
  • Down-Regulation / genetics
  • Extracellular Signal-Regulated MAP Kinases / metabolism
  • Gene Knockdown Techniques
  • Mesenchymal Stem Cells / cytology*
  • Mesenchymal Stem Cells / metabolism*
  • Mice, Inbred C57BL
  • Mice, Inbred ICR
  • Osteogenesis* / genetics
  • Signal Transduction
  • Up-Regulation / genetics
  • Wound Healing


  • Basic Helix-Loop-Helix Transcription Factors
  • Bone Morphogenetic Proteins
  • Tcf12 protein, mouse
  • Extracellular Signal-Regulated MAP Kinases