| Objective To investigate the effect of microRNA (miR)-196a on osteogenic differentiation of MC3T3-E1 cells by target regulation of histone deacetylase 9 (HDAC9). Methods MC3T3-E1 cells were divided into control group (Cont) group, induction group, miR-196a-mimics-NC group, miR-196a-mimics group, miR-196a-inhibitor-NC group, miR-196a-inhibitor group, miR-196a-mimics+pCMV-HDAC9-NC group, and miR-196a-mimics+pCMV-HDAC9 group. Osteogenic induction was performed after transfection according to the group. Quantitative fluorescent PCR was performed to measure the expression of miR-196a and HDAC9 in MC3T3-E1 cells. Alkaline phosphatase (ALP) activity was measured with a commercial kit. Alizarin red staining was performed to observe the degree of mineralization. Western blotting was performed to measure the expressions of HDAC9, ALP, Runt-related transcription factor 2 (RUNX2), collagen I (COL1), osteopontin (OPN), Histone H3, and Histone H3 (acetyl K9, K14 and K23). Results Compared to those in the Cont group, the expression of miR-196a, the expressions of ALP, Runx2, COL1, and OPN proteins, ALP activity, mineralization degree, and the acetylation levels of Histone H3 K9, K14, and K23 sites in MC3T3-E1 cells in the induction group increased (P<0.05), but the expression of HDAC9 mRNA and protein decreased (P<0.05). Transfection of miR-196a-mimics was able to significantly increase miR-196a expression, to decrease HDAC9 expression, and to increase ALP, Runx2, COL1, and OPN protein expression, ALP activity, mineralization degree, and Histone H3 acetylation. Transfection of miR-196a-inhibitor had the opposite effect. MiR-196a was able to target down-regulation of HDAC9 expression. Overexpression of HDAC9 was able to partially reverse the promoting effect of miR-196a mimics on osteogenic differentiation of MC3T3-E1 cells. Conclusion MiR-196a target down-regulates HDAC9 expression, increases histone acetylation level, and promotes osteogenic differentiation of MC3T3-E1 cells. |