RANK-mediated amplification of TRAF6 signaling leads to NFATc1 induction during osteoclastogenesis.
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.
Gohda
Jin
J
Division of Cellular and Molecular Biology, Department of Cancer Biology, The Institute of Medical Science, The University of Tokyo, Shirokane-dai, Minato-ku, Tokyo, Japan.
Akiyama
Toru
T
Koga
Takako
T
Takayanagi
Hiroshi
H
Tanaka
Sakae
S
Inoue
Jun-ichiro
J
D000818:Animals; D001665:Binding Sites; D019013:CD40 Antigens / Q000737:chemistry / Q000378:metabolism; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D003593:Cytoplasm / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism*; D006801:Humans; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D016328:NF-kappa B / Q000378:metabolism; D050778:NFATC Transcription Factors; D009687:Nuclear Proteins / Q000378:metabolism*; D010010:Osteoclasts / Q000166:cytology* / Q000378:metabolism*; D011485:Protein Binding; D053245:RANK Ligand; D053246:Receptor Activator of Nuclear Factor-kappa B; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D048029:TNF Receptor-Associated Factor 6 / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism*
D019013:CD40 Antigens; D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D008562:Membrane Glycoproteins; D016328:NF-kappa B; D050778:NFATC Transcription Factors; C494003:NFATC1 protein, human; C494005:Nfatc1 protein, mouse; D009687:Nuclear Proteins; D053245:RANK Ligand; D053246:Receptor Activator of Nuclear Factor-kappa B; D011993:Recombinant Fusion Proteins; D048029:TNF Receptor-Associated Factor 6; C505686:TNFRSF11A protein, human; C505688:TNFSF11 protein, human; C505687:Tnfrsf11a protein, mouse; C505689:Tnfsf11 protein, mouse; D014157:Transcription Factors