Depletion of EREG Enhances the Osteo/Dentinogenic Differentiation Ability of Dental Pulp Stem Cells via P38 MAPK and Erk Pathway in Inflammatory Microenvironment

Abstract

Background Epiregulin (EREG) is an important component of EGF, which was demonstrated to promote the osteo/dentinogenic differentiation of stem cells from SCAPs. Whether it could stimulate the osteo/dentinogenic differentiation of DPSCs in inflammatory environment is not clear. The purpose of the present study was to investigate the role of EREG on the DPSCs’ osteo/dentinogenic differentiation ability in inflammatory environment. Methods DPSCs were isolated from human third molars. Short hairpin RNAs (shRNAs) was used to knock down the EREG expression in DPSCs. Recombinant human EREG protein (rhEREG) was adopted in the rescue experiment. TNF-α was employed to mimic the inflammatory environment in vitro. Alkaline phosphatase (ALP) staining, Alizarin red staining, quantitative calcium analysis, and real time RT-PCR was used to detect the osteo/dentinogenic differentiation markers and related signaling pathways under normal and inflammatory environment. Results EREG depletion promoted ALP activity and mineralization ability of DPSCs. Expression of BSP, DMP-1, and DSPP were also enhanced. Besides, 50ng/ml rhEREG treatment weakened the osteo/dentinogenic differentiation potential. 10 ng/mL TNF-α treatment for 4h increased the expression of EREG in DPSCs. However, knockdown of EREG rescued the impaired osteo/dentinogenic differentiation ability caused by TNF-α treatment. Further mechanism study showed that, EREG depletion activated p38 MAPK and Erk signaling pathways in DPSCs under normal and inflammatory environment. Conclusions Our results demonstrated that EREG could inhibited the osteo/dentinogenic differentiation potential of DPSCs via p38 MAPK and Erk signaling pathways in normal and inflammatory environment.