Evidence that genetic deletion of the TNF receptor p60 or p80 in macrophages modulates RANKL-induced signaling.
In the current report, we investigated the possibility of a cross-talk between receptor activator of NF-kappaB ligand (RANKL) and tumor necrosis factor alpha (TNF-alpha) using macrophage cell lines derived from wild-type mice and from mice with genetic deletion of the type 1 TNF receptor (p60(-/-)), the type 2 TNF receptor (p80(-/-)), or both receptors (p60(-/-)p80(-/-)). Deletion of TNF receptors sensitized the cells to RANKL-induced NF-kappaB activation, in order from least to most sensitive of p60(-/-) less than p80(-/-) less than p60(-/-)p80(-/-). The effect on nuclear factor-kappaB (NF-kappaB) activation correlated with RANKL-induced IkappaBalpha kinase activation. Deletion of both TNF receptors also potentiated RANKL-induced c-Jun N-terminal kinase (JNK), extracellular signal-regulated kinase 1 and 2 (ERK1/2), and p38 mitogen-activated protein kinase (MAPK) activations in a dose- and time-dependent manner. Nitric oxide (NO) production and expression of inducible NO synthase (iNOS) and cyclooxygenase 2 (COX-2) induced by RANKL was also maximally induced in double knock-out cells. RANKL had no effect on the proliferation of wild-type cells, but deletion of TNF receptors induced growth modulatory effects. We also found that tumor necrosis factor (TNF) receptor-associated factor 6 (TRAF6), which mediates RANKL signaling, was constitutively bound to RANK in TNF receptor-deleted cells but not in wild-type cells, and this binding was enhanced by RANKL. Overall our results show that RANKL signaling is modulated by the TNF receptors and thus provide evidence of cross-talk between the receptors of 2 cytokines.
Cytokine Research Laboratory, Department of Experimental Therapeutics, Box 143, The University of Texas M. D. Anderson Cancer Center, 1515 Holcombe Blvd, Houston, TX 77030, USA.
Yasunari
Y
Takada
Bharat B
BB
Aggarwal
D000595:Amino Acid Sequence; D000818:Animals; D002352:Carrier Proteins / Q000276:immunology*; D017353:Gene Deletion; D007700:Kinetics; D008264:Macrophages / Q000276:immunology*; D008562:Membrane Glycoproteins / Q000276:immunology*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D008969:Molecular Sequence Data; D016328:NF-kappa B / Q000502:physiology; D010446:Peptide Fragments / Q000737:chemistry / Q000276:immunology; D053245:RANK Ligand; D053246:Receptor Activator of Nuclear Factor-kappa B; D018124:Receptors, Tumor Necrosis Factor / Q000172:deficiency* / Q000235:genetics; D015398:Signal Transduction / Q000276:immunology*
D002352:Carrier Proteins; D008562:Membrane Glycoproteins; D016328:NF-kappa B; D010446:Peptide Fragments; D053245:RANK Ligand; D053246:Receptor Activator of Nuclear Factor-kappa B; D018124:Receptors, Tumor Necrosis Factor; C505687:Tnfrsf11a protein, mouse; C505689:Tnfsf11 protein, mouse; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3