ABSTRACT
<p><b>OBJECTIVE</b>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.</p><p><b>METHODS</b>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 (NFATc1) was measured by reverse transcription PCR (RT-PCR) and Western blotting respectively.</p><p><b>RESULTS</b>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, NFATc1 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).</p><p><b>CONCLUSIONS</b>DAP12 pathway play an important role in regulating osteoclast differentiation induced by tensile strain.</p>