Involvement of miR-146a-5p/neurogenic locus notch homolog protein 1 in the proliferation and differentiation of STRO-1 human dental pulp stem cells.

Dental pulp stem cells (DPSCs) and stem cells from the apical papilla (SCAPs) are oral mesenchymal stem cells capable of self-renewal and have a potential for multilineage differentiation. Increasing evidence shows that microRNAs (miRNAs) play important roles in stem cell biology. Here, we focused on exploring miR-146a-5p and its relationship to the undifferentiated status of STRO-1 SCAPs and STRO-1 DPSCs, as well as its role during STRO-1 DPSC differentiation and proliferation. Our data indicated that baseline miR-146a-5p expression is significantly lower in STRO-1 SCAPs than in STRO-1 DPSCs and increased in the latter during osteogenic induction. Moreover, we identified miR-146a-5p as a key miRNA that promotes osteo/odontogenic differentiation of STRO-1 DPSCs and attenuates cell proliferation. Additionally, it was observed that STRO-1 DPSC mineralization results in the downregulation of notch receptor 1 (NOTCH1) and hes family bHLH transcription factor 1 (HES1). Interference with neurogenic locus notch homolog protein 1 (Notch 1) signaling was verified to enhance differentiation and suppress STRO-1 DPSC proliferation. It was further observed that miR-146a-5p directly targets the 3'-untranslated region (3'-UTR) of NOTCH1 and inhibits expression of both NOTCH1 and HES1mRNAs and Notch 1 and transcription factor HES-1 (HES-1) proteins in STRO-1 DPSCs. We conclude that miR-146a-5p exerts its regulatory effect on STRO-1 DPSC differentiation and proliferation partially by suppressing Notch signaling.