Effects of miR-92a and miR-19b on insulin gene expression in mouse pancreatic β-cells

AIM To investigate the effect of microRNA-92a （miR-92a） and microRNA-19b （miR-19b） on the insulin expression in mouse pancreatic β-cells. METHODS The relative expression levels of endogenous miR-92a and miR-19b in mouse insulinoma MIN6 cells were detected by qPCR. The MIN6 cells were divided into control group， and experimental groups I and II， with 3 samples in each group， and transfected with negative control miRNA （NC）， miR-92a and miR-19b， respectively. The over-expression of the miRNAs was detected by qPCR. The morphological changes and viability of the cells were detected by optical microscopy and CCK8 assay， respectively. The expression of insulin was detected by qPCR， Western blot and immunofluorescence. The possible mechanisms of miR-92a and miR-19b regulating insulin expression were analyzed by bioinformatics prediction， dual-luciferase reporter assay， and Western blot. RESULTS Compared with the adult pancreatic progenitor cells， the expression of endogenous miR-92a and miR-19b in the MIN6 cells was decreased significantly （P<0.05）. Over-expression of miR-92a and miR-19b had no effect on the viability of MIN6 cells， but inhibited the expression of insulin at mRNA and protein levels. miR-19b significantly inhibited the luciferase activity of NeuroD1 3′UTR and the protein expression of NeuroD1 （P<0.05）. miR-92a had a fine-tuning effect on the luciferase activity of NeuroD1 3′UTR and the protein expression of NeuroD1. CONCLUSION miR-92a and miR-19b inhibit the insulin expression in mouse pancreatic β-cells.