MicroRNA-125b-2 overexpression represses ectodermal differentiation of mouse embryonic stem cells.

microRNAs (miRNAs or miRS) have been demonstrated to be essential for neural development. miR-125b-2, presented on human chromosome 21, is overexpressed in neurons of individuals with Down syndrome (DS) with cognitive impairments. It has been reported that miR-125b-2 promotes specific types of neuronal differentiation; however, the function of miR-125b-2 in the early development of the embryo has remained to be fully elucidated. In the present study, a mouse embryonic stem cell (mESC) line was stably transfected with a miR-125b-2 lentiviral expression vector and found that miR-125b-2 overexpression did not affect the self-renewal or proliferation of mESCs. However, miR-125b-2 overexpression inhibited the differentiation of mESCs into endoderm and ectoderm. Finally, miR-125b-2 overexpression was found to impair all-trans-retinoic acid-induced neuron development in embryoid bodies. The findings of the present study implied that miR-125b-2 overexpression suppressed the differentiation of mESCs into neurons, which highlights that miR‑125b-2 is important in the regulation of ESC differentiation. The present study provided a basis for the further identification of novel targets of miR-125b-2, which may contribute to an enhanced understanding of the molecular mechanisms of ESC differentiation.