Abstract: Objective To investigate the profile of microRNA expression in mouse pre-osteoblast cell under cyclic stretch and to find the differences in microRNA which are related to TGF-β signaling pathway. Methods MC3T3-E1 cells were cultured in vitro. Normal cells were considered as controls and loading group cells loaded with 12% elongation for 3 hours, the differential expressed microRNA of MC3T3-E1 cell under mechanical strain conditions was screened by microRNA Microarray Technology, and then the Quantitative Real-time PCR was used to verify the differences associated with TGF-β signaling pathway, and bioinformatics was used to predict the target genes that may be regulated by it. Results Compared with the control group, 41 differentially expressed microRNAs were filtered in loading group, in which 20 were up-regulated and 21 were down-regulated(P values were less than 0.05 and the difference multiples were more than 1.5 times). The Quantitative Real-time PCR results showed that compared to the normal culture group, the expression level of miR-132-3p increased in loading group, consistent with the microarray results and there was significant difference (P<0.05). After software analysis, miR-132-3p target gene may be Smad2. Conclusion The expression profile of microRNA in osteoblast is significantly affected by cyclic stretch stress, these differences may influence the biological function of osteoblast by TGF-β signaling pathway or its related signal molecules.

Key words: Mechanical strain, osteoblast, TGF-β signaling pathway, microRNA