[Effects of DNAX-associated protein 12 signal pathways on differentiation of mouse monocytes RAW264.7 into osteoclasts by tensile strain].

Objective To explore the effect of DNAX-associated protein 12(DAP12) pathway on the transformation from mouse monocytes RAW264.7 to osteoclasts induced by tensile strain.Methods DAP12shRNA plasmid was constructed and introduced to RAW264.7 cells.Then we supplied tensile strain to RAW264.7 cells by four-point bending system. The mRNA or protein expression of DAP12,tartrate-resistant acid phosphatase(TRAP),tyrosine kinases Btk and Tec and nuclear facior of activated T cells 1 (NFATc 1 ) was measured by reverse transcription PCR (RT-PCR) and Western blotting respectively.Results The expression of DAP12 mRNA (0.112 ± 0.025 ) and protein (0.193 ± 0.015 ) both declined sharply after plasmid being introduced into monocytes RAW264.7 ( P ＜ 0.05 ). After silencing DAP12 expression in RAW264.7 cells by RNA interference,tensile strain-induced TRAP mRNA expression of RAW264.7 cells increased at 6 h(0.671 ±0.031) and 12 h(0.800±0.043) (P＜0.05),but it was weaker than non-RNA-interference-groups at each time point(P ＜0.05).After silencing DAP12 expression in RAW264.7 cells by RNA interference,the expressions of Btk,Tec,NFATcl increased as time passed (6,12 h) ( P ＜ 0.05 ),but the expressions on corresponding time decreased sharply compared with those in control groups ( P ＜ 0.05 ).Conclusions DAP12 pathway play an important role in regulating osteoclast differentiation induced by tensile strain. Key words: Gene silencing; Stress, mechanical; Monocytes; DAP12 signal pathway