Effects Of DAP12Signal Pathways On Differentiation Of Mouse Monocytes Raw264.7into Osteoclasts By Compressive Stress

Background and objective:Orthodontic tooth movement is achieved by modeling and remodeling processes of the alveolar bone, which are triggered by the stress/strain distribution in the periodontium. The modeling and remodeling processes of the alveolar bone induced by mechanical stimulus are achieved mainly through the osteoblast and osteoclast. Osteoclast activation occurs at the pressure side of the alveolar bone of the orthodontic tooth, and subsequently occurs resorption of the alveolar bone, which thus induce the orthodontic tooth movement. It is necessary to understand the regulatory mechanism of signals transduction in osteoclast activation by mechanical stimuli. However, it is not definitively determined what the signals transduction involved in the osteoclast activation induced by mechanical stimuli. Therefore, in order to better understand it, we studied the expression of DAP12signal pathways in mouse monocytes raw264.7by compressive stressMethods:mouse monocytes raw264.7(the pre-osteoclast line) were subjected by four-point bending system. Observed the osteoclast differentiation in vitro.Examined the expression of DAP12and DAP12-associated receptors mRNA after compressive stress stimulus by RT-PCR,the expression of DAP12protein by Western Blotting, and the expression of IL-1,IL-6by ELISA. Western Blotting also used to examine the expression of TRAP, NFATc1, Btk and Tec of the mouse monocytes raw264.7[knockdown of DAP12gene,using a short hairpin RNA (shRNA)] after compressive stressResults:1The amount of mouse monocytes raw264.7increase,and the volume of it enlarges,the number of the nucleus in it increase in vitro; The expression of DAP12and TRAP mRNA and DAP12protein increase in it by compressive stress.2Compressive stress can activate the DAP12-associated receptors: TREM-2and MDL-1. Using the disintegrin echistatin (a competitive integrin receptor antagonist) to inhibit the effects of integrin can decrease the activation of DAP12-associated receptors:TREM2and MDL-1after compressive stress stimulate in mouse monocytes raw264.7cells. Moreover, compressive stress can upregulate the secretion of IL-1and IL-6in it3Short hairpin RNA silencing the DAP12expression decreases the expression of TRAP, NFATc1, Btk and Tec when mouse monocytes raw264.7stimulate by compressive stress.Conclusions:The mouse monocytes raw264.7succeed to differente into osteoclast in vitro, Compressive stress increased the expression of DAP12and DAP12-associated receptors and cyto-factors, Silencing DAP12gene can decreases the expression of DAP12, TRAP, NFATc1, Btk,Tec. Combining the results, we may presume that DAP12signal pathways may involve in the osteoclast activation induced by compressive stress. DAP12signal pathways contain a larg family of receptor,cyto-factor and yeast such as DAP12,TRAP, IL-1, IL-6, NFATc1, Btk, Tec.Morever, DAP12play a key role in this signal pathways and it may cooperate with RANK signal pathways through the tyrosine kinases Btk and Tec.