Identification and differential expression of microRNAs in 1, 25-dihydroxyvitamin D3-induced osteogenic differentiation of human adipose-derived mesenchymal stem cells.

The aim of this study was to identify specific microRNAs (miRNAs) and their regulatory roles in the process of 1, 25-dihydroxyvitamin D3-induced (VD3-induced) osteogenic differentiation of human adipose-derived Mesenchymal stem cells (hAMSCs). The differentially expressed miRNAs in VD3-induced hAMSCs was examined. The putative target genes of these miRNAs were predicted. A total of 76 conserved miRNAs, including 18 miRNAs were significantly up-regulated and 58 miRNAs were significantly downregulated, and significantly differentially expressed between the two samples. The expression of 4 upregulated miRNAs (miR-1-3p, miR-1247-5p, miR-217, and miRNA-483) and 5 downregulated miRNAs (miR-1284, miR-218, miR-582-3p, miR-187-3p, and miRNA-122-5p) were verified. The highly enriched GOs and KEGG pathway showed target genes of these miRNAs were significantly involved in multiple biological processes (signal transduction, cell differentiation, cell adhesion and cell proliferation), and several osteogenic pathways (MAPK signaling pathway, TGF-β/BMP signaling pathway, and Wnt signaling pathway). Finally, TGF-β/BMP signaling pathway was selected for target verification and function analysis. We observed that a number of osteo-genes in the TGF-β/BMP superfamily, such as BMPRI, BMPRII, TGFBRI, TGFBRII, BMP4, TGFβ, Smad2, 3, 8, were predicted to be target gene of the differentially expressed miRNAs. Among them, TGFB, BMP4, BMPRI, and Smad8, which are positive regulators in osteoblast differentiation, were confirmed to be significantly up-regulated in VD3-induced cells by qRT-PCR; while Smad6 and activinRI, which are negative regulators of the TGF-β/BMP superfamily, were shown to be significantly down-regulated. These results will help to understand the role of miRNA in the regulation of the osteogenic differentiation of hAMSCs.