Differentially expressed microRNAs during the differentiation of muscle-derived stem cells into insulin-producing cells, a promoting role of microRNA-708-5p/STK4 axis

OBJECTIVE: Stem cell therapy is a promising approach for diabetes via promoting the differentiation of insulin-producing cells (IPCs). This study aimed to screen the differentially expressed miRNAs (DEmiRNAs) during the differentiation of muscle-derived stem cells (MDSCs) into IPCs, and uncover the underlying function and mechanism of a specific DEmiRNA, miR-708-5p. METHODS: MDSCs were successfully isolated from the leg muscle of rats, and were induced for IPCs differentiation through a five-stage protocol. miRNA microarray assay was performed for screening DEmiRNAs during differentiation. The features of MDSCs-derived IPCs were identified by qRT-PCR, flow cytometry, and immunofluorescence staining. The targeting of STK4 by miR-708-5p was examined by luciferase assay. The protein expression of STK4, YAP1, and p-YAP1 was determined by Western blot and immunofluorescence staining. RESULTS: MDSCs were successfully isolated and differentiated into IPCs. A total of 12 common DEmiRNAs were obtained during five-stage differentiation. Among them, miR-708-5p that highly expressed in MDSCs-derived IPCs was selected. Overexpression of miR-708-5p upregulated some key transcription factors (Pdx1, Ngn3, Nkx2.2, Nkx6.1, Gata4, Gata6, Pax4, and Pax6) involving in IPCs differentiation, and increased insulin positive cells. In addition, STK4 was identified as the target gene of miR-708-5p. miR-708-5p overexpression downregulated the expression of STK4 and the downstream phosphorylated YAP1. CONCLUSIONS: There were 12 DEmiRNAs involved in the differentiation of MDSCs into IPCs. miR-708-5p promoted MDSCs differentiation into IPCs probably by targeting STK4-mediated Hippo-YAP1 signaling pathway.