Abstract: Objective To investigate the protective effect of spleen tyrosine kinase (SYK) on oxidative stress (OS)-induced injury and cell apoptosis in mouse osteoblasts MC3T3-E1 and the mechanism. Methods Osteoblast MC3T3-E1 was incubated with hydrogen peroxide (H2O2) to establish OS model. The mRNA expression of SYK was measured by quantitative real-time PCR (RT-qPCR). The protein expression levels of SYK, AKT, p-AKT and UCP2 were detected by Western blot. Recombinant plasmids pcDNA.3.1-SYK and pcDNA.3.1-UCP2 were constructed and separately transfected into MC3T3-E1. AKT phosphorylation was inhibited by AKT inhibitor HIMO. Cell apoptosis was measured by Annexin-V FITC/PImethod. Caspase-3 activity and reactive oxygen species (ROS) level were detected by kit methods. Results SYK was decreased by OS in osteoblasts (P<0.01). The overexpression of SYK significantly down-regulated cell apoptosis (P<0.05), caspase-3activity (P<0.01)，ROS level (P<0.01) induced by OS. Overexpression of SYK obviously increased AKT phosphorylation (P<0.05) and UCP2 expression (P<0.01). The inhibition of AKT phosphorylation could abolish the effects of SYK on cell apoptosis and UCP2 expression (P<0.01). UCP2 was overexpressed in MC3T3-E1 with SYK overexpression and AKT inhibition, and the cell apoptosis (P<0.05) and ROS level (P<0.01) were both markedly decreased. Conclusions The overexpression of SYK can prevent osteoblasts from injury induced by OS via regulating AKT/UCP2.

Key words: SYK, AKT, UCP2, osteoblasts, cell injury, apoptosis