Time series clustering analysis of genes during osteogenic differentiation of human mesenchymal stem cells.

To investigate the gene expression pattern and related biological changes during osteogenic differentiation of human mesenchymal stem cells (hMSCs), we downloaded expression data for four uninduced hMSC samples, and 12 osteogenic induction samples at day 2, 8, 12 or 25, in the GSE37558 dataset. Differentially expressed genes (DEGs) between groups were screened, followed by short time-series expression miner (STEM) analysis and weighted gene co-expression network analysis (WGCNA). Osteogenic differentiation-related genes were extracted from the GeneCards database. Next, functional enrichment was performed, and protein-protein interaction (PPI) and lncRNA-miRNA-mRNA networks were constructed. Compared to uninduced hMSC samples, 163, 341, 447 and 537 DEGs were found in osteogenic induction samples at day 2, 8, 12 and 25, respectively, showing a sustainably increased trend. From STEM, WGCNA and the GeneCards database, a total of 107 key genes associated with osteogenic differentiation were screened; these genes were enriched in biological processes, such as ossification, ECM-receptor interaction, vasculature development, cartilage development and bone mineralization, as well as the Wnt signaling pathway and the chemokine signaling pathway. The PPI network identified four hub genes, STAT5A, TWIST1, FOXO1 and LEP. The lncRNA-miRNA-mRNA network revealed regulatory axes for STAT5A, FOXO1 and LEP. Three and two regulatory axes were found for STAT5A and LEP, respectively. Multiple regulatory axes for FOXO1 were found, such as MIR155HG-miR-223-FOXO1. This study identifies candidate key targets that may play important roles in regulating osteogenic differentiation of hMSCs, and provides novel information to further investigate the molecular regulation mechanism. More experiments are required to evaluate the effects of these genes on osteogenic differentiation of hMSCs.