Toll-like receptor 9 regulates tumor necrosis factor-alpha expression by different mechanisms. Implications for osteoclastogenesis.
CpG oligodeoxynucleotides (CpG-ODNs), mimicking bacterial DNA, stimulate osteoclastogenesis via Toll-like receptor 9 (TLR9) in receptor activator of NF-kappa B ligand (RANKL)-primed osteoclast precursors. This activity is mediated via tumor necrosis factor (TNF)-alpha induction by CpG-ODN. To further reveal the role of the cytokine in TLR9-mediated osteoclastogenesis, we compared the ability of CpG-ODN to induce osteoclastogenesis in two murine strains, BALB/c and C57BL/6, expressing different TNF-alpha alleles. The induction of osteoclastogenesis and TNF-alpha release by CpG-ODN was by far more noticeable in BALB/c-derived than in C57BL/6-derived osteoclast precursors. Unexpectedly, as revealed by Northern analysis, CpG-ODN induction of TNF-alpha mRNA increase was more efficient in C57BL/6-derived cells. The cytokine transcript abundance was increased due to both increased message stability and rate of transcription. The difference between the two cell types was the result of a higher transcription rate in CpG-ODN-induced C57BL/6-derived cells caused by a single nucleotide polymorphism in kappa B2a site within the TNF-alpha promoter sequence. CpG-ODN enhanced the rate of the cytokine translation in BALB/c-derived cells. Thus, CpG-ODN modulated both transcription and translation of TNF-alpha. The induction of transcription was more evident in C57BL/6-derived cells, while the induction of translation took place only in BALB/c-derived osteoclast precursors. Altogether the cytokine was induced to a larger extent in BALB/c-derived osteoclast precursors, consistent with the increased CpG-ODN osteoclastogenic effect in these cells.
H. Hubert Humphrey Center for Experimental Medicine and Cancer Research, The Hebrew University Faculty of Medicine, P. O. Box 12272, Jerusalem 91120, Israel.
Alla
A
Amcheslavsky
Wei
W
Zou
Zvi
Z
Bar-Shavit
D000818:Animals; D015152:Blotting, Northern; D002352:Carrier Proteins / Q000008:administration & dosage / Q000502:physiology; D002454:Cell Differentiation / Q000187:drug effects; D004268:DNA-Binding Proteins / Q000502:physiology*; D005786:Gene Expression Regulation / Q000502:physiology*; D008297:Male; D008562:Membrane Glycoproteins / Q000008:administration & dosage / Q000502:physiology; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D016328:NF-kappa B / Q000502:physiology; D009838:Oligodeoxyribonucleotides / Q000494:pharmacology; D010010:Osteoclasts / Q000187:drug effects / Q000502:physiology*; D020641:Polymorphism, Single Nucleotide; D011401:Promoter Regions, Genetic / Q000235:genetics; D053245:RANK Ligand; D012333:RNA, Messenger / Q000032:analysis; D053246:Receptor Activator of Nuclear Factor-kappa B; D011956:Receptors, Cell Surface / Q000502:physiology*; D013045:Species Specificity; D013234:Stem Cells / Q000502:physiology; D051217:Toll-Like Receptor 9; D014158:Transcription, Genetic; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics*
C408982:CPG-oligonucleotide; D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D008562:Membrane Glycoproteins; D016328:NF-kappa B; D009838:Oligodeoxyribonucleotides; D053245:RANK Ligand; D012333:RNA, Messenger; D053246:Receptor Activator of Nuclear Factor-kappa B; D011956:Receptors, Cell Surface; C495370:Tlr9 protein, mouse; C505687:Tnfrsf11a protein, mouse; C505689:Tnfsf11 protein, mouse; D051217:Toll-Like Receptor 9; D014409:Tumor Necrosis Factor-alpha