ABSTRACT
Objective To screen the secretory factor-related, mechanoresponsive microRNAs (miRNA) of osteocytes. Methods Cyclic mechanical tensile strain (ε=2.5,f=0.5 Hz) was applied to osteocytes and osteoblasts cultured in vitro respectively, and the differentially expressed miRNAs only in the osteocytes were screened out by using miRNA chip. Through bioinformatics technology, in these differentially expressed miRNAs, the target genes of secretory factors including insulin-like growth factor-1(IGF-1), nitric oxide synthesase (NOS), fibroblast growth factor 23 (FGF23) and sclerostin (SOST) were further screened out. Then the selected miRNAs were compared with the biochip detected, differentially expressed miRNAs in femur bone of the mice which were trained on treadmill, and four of these miRNAs were randomly selected for quantitative PCR verification. Results For the 77 differentially expressed miRNAs only in the mechanically strained osteocytes in vitro, 22 miRNAs whose target genes were the 4 secreted factors (IGF-1, NOS, FGF23 and SOST), were screened out. Moreover, a total of 11 miRNAs in the 22 miRNAs were differentially expressed in femur bone of the treadmill trained mice with the same trend as those in osteocytes in vitro, and the randomly selected miR-361-3p, miR-3082-5p, miR-6348 and miR-706 were confirmed to be differentially expressed with the same trend in femur bone and osteocytes. Conclusions These mechanoresponsive miRNAs differentially expressed only in osteocytes, such as miR-361-3p, miR-3082-5p, miR-6348 and miR-706, probably influence osteoblastic differentiation or bone metabolism through regulating the secretory factors.