Conclusion
These findings indicate that EREG could enhance cell proliferation in dental tissue-derived MSCs by activating MEK/Erk and JNK signalling pathways.
Methods
SCAPs were isolated from apical papillae of immature third molars. Retroviral short hairpin RNA (shRNA) was used to silence EREG gene expression, and human recombinant EREG protein was used to stimulate SCAPs. SCAP proliferation was examined using tetrazolium dye colorimetric assay/cell growth curve. Western blotting was performed to detect expressions of extracellular signal-regulated protein kinases 1 and 2 (Erk1/2), mitogen-activated protein kinases 1 and 2 (MEK1/2), protein kinase B (Akt), p38 mitogen-activated protein kinase (p38 MAPK) and c-Jun N-terminal kinase (JNK).
Results
Depletion of EREG with shRNA inhibited SCAP proliferation and repressed phosphorylation of Erk1/2 and JNK. Human recombinant EREG protein promoted cell proliferation and enhanced Erk1/2, MEK and JNK phosphorylation in SCAPs. Furthermore, blocking MEK/Erk signalling with specific Erk1/2 inhibitor PD98059, or JNK signalling with specific inhibitor SP600125, abolished effects of EREG on cell proliferation.