ABSTRACT
<p><b>OBJECTIVE</b>To investigate the role of miR-144-3p in regulating osteogenic differentiation of bone marrow mesenchymal stem cells and predict its target genes.</p><p><b>METHODS</b>Rat bone marrow mesenchymal stem cells (BMSCs) with induced osteogenic differentiation were examined for the expressions of Runx2, OCN and miR-144-3p. The effects of transfection with a miR-144-3p mimic or a miR-144-3p inhibitor were tested on the osteogenic differentiation of the BMSCs. The changes in the expressions of the predicted target of miR-144-3p in the BMSCs during induced osteogenic differentiation were examined using Western blotting and qRT-PCR.</p><p><b>RESULTS</b>Rat BMSCs with induced differentiation into osteoblasts exhibited a progressive increase in the expressions of Runx2 and OCN (two markers of osteogenic differentiation), while the expression of miR-144-3p gradually decreased during the differentiation till reaching the lowest level at 21 days of induction. In rat BMSCs, transfection with the miR-144-3p mimic significantly decreased ALP activity ( < 0.05) wile transfection with the miR-144-3p inhibitor significantly increased ALP activity ( < 0.05) in rat BMSCs. Analysis based on miRanda, microRNA.org database and TargetScan suggested that Smad4 was the most likely target gene of miR-144-3p. The results of qRT-PCR showed no significant differences in expression levels of Smad4 among the cells with different treatments ( > 0.05), while Western blotting revealed a significantly decreased expression of Smad4 in the cells transfected with miR-144-3p mimics and an increased Smad4 expression in the cells transfected with the miR-144-3p inhibitor as compared with the control cells ( < 0.05).</p><p><b>CONCLUSIONS</b>miR-144-3p participates in the regulation of osteogenic differentiation of rat BMSCs, and its inhibitory effect on osteogenic differentiation is achieved probably by decreasing the expression level of Smad4.</p>