Overexpression of miR-21 promotes neural stem cell proliferation and neural differentiation via the Wnt/β-catenin signaling pathway in vitro

The primary aim of the present study was to examine the effects of microRNA-21 (miR-21) on the proliferation and differentiation of rat primary neural stem cells (NSCs) in vitro. miR-21 was overexpressed in NSCs by transfection with a miR-21 mimic. The effects of miR-21 overexpression on NSC proliferation were revealed by Cell Counting kit 8 and 5-ethynyl-2-deoxyuridine incorporation assay, and miR-21 overexpression was revealed to increase NSC proliferation. miR-21 overexpression was confirmed using reverse transcription-quantitative polymerase chain reaction (RT-qPCR). mRNA and protein expression levels of key molecules (-catenin, cyclin D1, p21 and miR-21) in the Wnt/-catenin signaling pathway were studied by RT-qPCR and western blot analysis. RT-qPCR and western blot analyses revealed that miR-21 overexpression increased -catenin and cyclin D1 expression, and decreased p21 expression. These results suggested that miR-21-induced increase in proliferation was mediated by activation of the Wnt/-catenin signaling pathway, since overexpression of miR-21 increased -catenin and cyclin D1 expression and reduced p21 expression. Furthermore, inhibition of the Wnt/-catenin pathway with FH535 attenuated the influence of miR-21 overexpression on NSC proliferation, indicating that the factors activated by miR-21 overexpression were inhibited by FH535 treatment. Furthermore, overexpression of miR-21 enhanced the differentiation of NSCs into neurons and inhibited their differentiation into astrocytes. The present study indicated that in primary rat NSCs, overexpression of miR-21 may promote proliferation and differentiation into neurons via the Wnt/-catenin signaling pathway in vitro.