miR-155 Inhibits Mouse Osteoblast Differentiation by Suppressing SMAD5 Expression

Abstract EN

Osteogenesis from preosteoblasts is important for bone tissue engineering.

MicroRNAs are a class of endogenous small RNA molecules that potentially modulate osteogenesis.

In this study, we found that miR-155 expression was downregulated in a time-dependent manner in cells of the preosteoblast cell line MC3T3-E1 after osteogenic induction using bone morphogenetic protein 2 (BMP2).

Transfection with miR-155 decreased alkaline phosphatase (ALP) activity, ALP expression, and the staining intensity of Alizarin Red in MC3T3-E1 cells treated with BMP2, whereas treatment with miR-155 inhibitor promoted BMP2-induced osteoblast differentiation.

The luciferase assay confirmed that miR-155 can bind to the 3′ untranslated region of SMAD5 mRNA.

miR-155 transfection significantly decreased the expression of SMAD5 protein and mRNA in MC3T3-E1 cells under control media and the p-SMAD5 protein level during osteogenesis.

After transfecting cells with the SMAD5 overexpression plasmids, the inhibitory effect of miR-155 on osteogenesis was significantly attenuated.

In conclusion, miR-155 inhibited osteoblast differentiation by downregulating the translation of SMAD5 in mouse preosteoblast cells.

Inhibition of miR-155 promoted osteogenic potential and thus it can be used as a potential target in the treatment of bone defects.