RANK-mediated amplification of TRAF6 signaling leads to NFATc1 induction during osteoclastogenesis

EMBO J. 2005 Feb 23;24(4):790-9. doi: 10.1038/sj.emboj.7600564. Epub 2005 Jan 27.


RANK and CD40 activate NF-kappaB and MAPKs to similar levels via TRAF6. Even though overexpression of TRAF6 results in osteoclast formation, RANK but not CD40 promotes osteoclastogenesis. To understand the molecular basis for RANK-specific activity in osteoclastogenesis, we created an osteoclast formation system driven by anti-human CD40 antibody-mediated stimulation of a chimeric receptor, h40/mRK, which consists of the extracellular domain of human CD40 and the transmembrane and cytoplasmic domains of mouse RANK. By introducing mutations into three TRAF6-binding sites of RANK, we found that h40/mRK with a single TRAF6-binding site efficiently induced Ca2+ oscillation and expression of NFATc1, a master switch in osteoclastogenesis, whereas CD40 carrying a single TRAF6-binding site did not. However, expression of CD40 that was approximately 100 times greater than that of h40/mRK resulted in osteoclast formation, indicating that the RANK-TRAF6 signal is more potent than the CD40-TRAF6 signal in terms of NFATc1 activation and osteoclastogenesis. These results suggest that RANK may harbor a specific domain that amplifies TRAF6 signaling.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Binding Sites
  • CD40 Antigens / chemistry
  • CD40 Antigens / metabolism
  • Carrier Proteins / genetics
  • Carrier Proteins / metabolism*
  • Cells, Cultured
  • Cytoplasm / metabolism
  • DNA-Binding Proteins / metabolism*
  • Humans
  • Membrane Glycoproteins / genetics
  • Membrane Glycoproteins / metabolism*
  • Mice
  • NF-kappa B / metabolism
  • NFATC Transcription Factors
  • Nuclear Proteins / metabolism*
  • Osteoclasts / cytology*
  • Osteoclasts / metabolism*
  • Protein Binding
  • RANK Ligand
  • Receptor Activator of Nuclear Factor-kappa B
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism
  • Signal Transduction*
  • TNF Receptor-Associated Factor 6 / metabolism*
  • Transcription Factors / metabolism*


  • CD40 Antigens
  • Carrier Proteins
  • DNA-Binding Proteins
  • Membrane Glycoproteins
  • NF-kappa B
  • NFATC Transcription Factors
  • NFATC1 protein, human
  • Nfatc1 protein, mouse
  • Nuclear Proteins
  • RANK Ligand
  • Receptor Activator of Nuclear Factor-kappa B
  • Recombinant Fusion Proteins
  • TNF Receptor-Associated Factor 6
  • TNFRSF11A protein, human
  • TNFSF11 protein, human
  • Tnfrsf11a protein, mouse
  • Tnfsf11 protein, mouse
  • Transcription Factors