Circular RNA expression profiles during the differentiation of human umbilical cord-derived mesenchymal stem cells into cardiomyocyte-like cells

So far, there were no reports on circular RNA (circRNA) expression profiles in the differentiation of human umbilical cord-derived mesenchymal stem cells (hUCMSCs) into cardiomyocyte-like cells induced by 5-aza. In this study, hUCMSCs were isolated from umbilical cords and induced with 5-aza for 14 days. Immunofluorescence staining, real-time reverse transcription polymerase chain reaction (RT-PCR), and western blot of cardiac troponin I and -sarcomeric actin on hUCMSCs between Days 14 and 0 were performed. The expression profile of circRNAs was analyzed by microarray and validated with RT-PCR. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes analyses were performed to identify the functions of differentially expressed genes and related pathways. The connections between circRNAs and microRNAs were explored by using Cytoscape. The results showed that a total of 226 circRNAs were calculated as differentially expressed during the differentiation. Among them, 127 were upregulated and 99 were downregulated. We selected circRNAs that were upregulated by more than five-fold and downregulated by more than three-fold. Ultimately, 74 differentially expressed circRNAs that were highly conserved on Day 14 after induction compared to Day 0 were identified. Among them, 41 were upregulated and 33 were downregulated. Four upregulated circRNAs (circRNA_01536, circRNA_04411, circRNA_09169, and circRNA_09905) and four downregulated circRNAs (circRNA_00699, circRNA_01183, circRNA_01978, and circRNA_16804) were randomly confirmed by RT-PCR. GO analysis suggested a number of cell proliferation and differentiation related physiological processes and pathways, such as the Wnt signaling pathway and others. Network analysis uncovered three potential key circRNAs, that is, circRNA_05432, circRNA_08441, and circRNA_01536.