Polycomb group protein Bmi1 is required for the neuronal differentiation of mouse induced pluripotent stem cells.

Induced pluripotent stem cells (iPSCs) reprogrammed by somatic cells may be used as a potentially novel treatment regimen in stem cell regenerative medicine, particularly in the central nervous system (CNS). In the present study, iPSCs were generated using mouse embryonic fibroblasts by ectopic overexpression of Sox-2, Oct-3/4, Klf-4 and c-Myc, and cultured under the same conditions as that used for embryonic stem cells. The neuronal differentiation capacity of mouse iPSCs was examined, and the involvement of the formation of embryoid bodies was assessed. The results suggested that after 15 days of neuronal inducement, Nestin, Vimentin and Glast protein expression levels were significantly increased in the mouse iPSC-derived cells. Additionally, Bmi1, which is selectively expressed in differentiated postnatal adult stem cells. such as hematopoietic stem cells and neural stem cells, was required for establishment of the neuronal differentiation of mouse iPSCs. In order to assess the effects of Bmi1 in neuronal differentiation, Bmi1 expression levels were inhibited with the small molecule PTC-209. The results showed that inhibition of Bmi1 expression reduced the expression of neuronal markers, such as Nestin, compared with the controls. These results suggested that mouse iPSCs can be induced to achieve neuronal differentiation. More interestingly, Bmi1 was required during the neuronal differentiation of mouse iPSCs.