Epiregulin enhances odontoblastic differentiation of dental pulp stem cells via activating MAPK signalling pathway.

Dixin Cui,Mian Wan,Xin Zhou,Hongyu Li,Liwei Zheng,Xuedong Zhou,Jiani Xiao,Yachuan Zhou,Ying Liu,Quan Yuan,Yiran Peng,Yi Yu

doi:10.1111/cpr.12680

Abstract

ObjectivesThe odontoblastic differentiation of dental pulp stem cells (DPSCs) contributes to tertiary dentin formation. Our previous study indicated that epiregulin (EREG) enhanced odontogenesis potential of dental pulp. Here, we explored the effects of EREG during DPSC odontoblastic differentiation.MethodsThe changes in EREG were detected during tertiary dentin formation. DPSCs were treated with recombinant human EREG (rhEREG), EREG receptor inhibitor gefitinib and short hairpin RNAs. The odontoblastic differentiation was assessed with ALP staining, ALP activity assay, alizarin red S staining and real‐time RT‐PCR of DSPP, OCN, RUNX2 and OSX. Western blot was conducted to examine the levels of p38 mitogen‐activated protein kinase (p38 MAPK), c‐Jun N‐terminal kinase (JNK) and extracellular signal‐regulated kinase 1/2 (Erk1/2). The expression of EREG and odontoblastic differentiation‐related markers was investigated in human dental pulp from teeth with deep caries and healthy teeth.ResultsEpiregulin was upregulated during tertiary dentin formation. rhEREG enhanced the odontoblastic differentiation of DPSCs following upregulated p38 MAPK and Erk1/2 phosphorylation, but not JNK, whereas depletion of EREG suppressed DPSC differentiation. Gefitinib decreased odontoblastic differentiation with decreased phosphorylation of p38 MAPK and Erk1/2. And suppression of p38 MAPK and Erk1/2 pathways attenuated DPSC differentiation. In human dental pulp tissue, EREG upregulation in deep caries correlates with odontoblastic differentiation enhancement.ConclusionEpiregulin is released during tertiary dentin formation. And EREG enhanced DPSC odontoblastic differentiation via MAPK pathways.

Highlights

Dental caries is one of the most common diseases in dentistry,[1,2] which contributes to non‐vital teeth and further teeth missing
Regardless of which materials are used in Indirect pulp capping (IPC), the production of tertiary dentin is a reaction of dental pulp stem cells (DPSCs) to the high pH, unlike the natural dentinogenesis process
Our previous study compared gene expressions of fetal dental papilla cells (FDPCs) and human adult dental pulp cells (ADPCs) by human growth fac‐ tor array, in which we found that the expression of EREG in FDPCs was significantly higher than that in ADPCs, and ADPCs comple‐ mented with EREG‐stimulated non‐dental epithelial cells differen‐ tiate to dental epithelial cells.[20]

Summary

| INTRODUCTION

Dental caries is one of the most common diseases in dentistry,[1,2] which contributes to non‐vital teeth and further teeth missing. Indirect pulp capping (IPC), a vital pulp therapy (VPT), is always per‐ formed in the clinic to preserve pulp vitality and subsequent natural teeth It is accomplished by applying pulp capping agents, usually calcium hydroxide, over the deep cavities to induce tertiary dentin formation in the underlying dental pulp, and protect pulp tissue from injurious stimuli from outside. The EGF family, including EGF, transforming growth factor‐α (TGF‐α), epiregulin (EREG) and amphiregulin, reg‐ ulates proliferation and cytodifferentiation via binding to epidermal growth factor receptor (EGFR) on cell membrane. This induces pro‐ tein‐tyrosine kinase activity of EREG intracellular tyrosine residues and stimulates the mitogen‐activated protein kinase (MAPK) signalling pathway.[10,11]. The potential role of MAPK signalling pathway in EREG‐en‐ hanced odontoblastic differentiation was analysed

| Ethics statement

| DISCUSSION