The potential function of miR‐135b‐mediated JAK2/STAT3 signaling pathway during osteoblast differentiation

Abstract MC3T3‐E1 cells were divided into Blank, miR‐135b mimics, miR‐135b inhibitors, AG490, and miR‐135b inhibitors + AG490 groups. Cell viability was determined by MTT, alkaline phosphatase (ALP) activity by the corresponding kit, and mineralization by alizarin red staining. Furthermore, miR‐135b, osteoblast‐specific genes, and JAK2/STAT3 were detected through quantitative real‐time polymerase chain reaction and Western blotting. MiR‐135b downregulation was identified with increased JAK2 during osteoblast differentiation. JAK2 was confirmed as a target gene of miR‐135b by dual‐luciferase reporter assay. MC3T3‐E1 cells in both miR‐135b mimics and AG490 groups manifested decrease in cell viability, ALP activity, and mineralized nodes, as well as reductions in osteoblast‐specific genes and proteins of JAK2, p‐JAK2, and p‐STAT3, but increase in cell apoptosis. However, opposite changes of the above factors were shown in cells from miR‐135b inhibitors group. Notably, AG490 could reverse promotion effects of miR‐135b inhibitors on osteoblast differentiation. Inhibiting miR‐135b could activate the JAK2/STAT3 signaling pathway, thereby improving the cell viability and promoting the osteoblast differentiation.