CpG Oligodeoxynucleotides Inhibit RANKL-Induced Osteoclast Formation by Upregulating A20 Deubiquitinase in RAW 264.7 Cells

Figure 5

Inhibitory effect of CpG-ODN on RANKL-induced osteoclast formation via TLR9. (a, b) mRNA and protein expressions of osteoclast-specific molecules such as NFATc1, TRAP, cathepsin K, and CA-II were measured in TLR9 siRNA transfected RAW 264.7 cells incubated with both RANKL and CpG-ODN. (c) RANKL-TRAF6-dependent signal pathway initiates differentiation and formation of multinucleated osteoclasts through activation of osteoclast-specific molecules, together with maturation of interleukin-1b. CpG-ODN amplifies IL-1β expression, in turn leading to A20 expression. Finally, CpG-ODN-IL-1β-A20-TRAF6 signal transduction plays a negative role in RANKL-induced osteoclast formation. Abbreviation: NC: negative control; NFATc1: nuclear factor of activated T cells c1; TRAP: tartrate-resistant acid phosphatase; CA-II: carbonic anhydrase-II. Error bars represent standard deviation of the measurement of three separate samples ( and ).

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