DMP1's signal pathway via MAPK-ERK

Objective Dentin matrix phosphoprotein 1(DMP1) is a non-collagenous, acidic extracellular matrix protein expressed chiefly in bone and dentin. The present study was aimed to investigate whether DMP1 can trigger MAPK signalling pathway in hMSC, MC3T3-E1 and MDPC-23 cells. Methods The activation of MAPK-ERK by rDMP1F / C and inhibition of ERK by MAPK inhibitor at different timepoints in hMSC, MC3T3-E1 and MDPC-23 cells was detected using Western blot. The inhibition of ERK cytoplasm / nucleus translocation by the MAPK inhibitor was detected using immunofluorescence microscopy. The activation of MAPK-ERK signalling pathway by DMP1 was further validated through knowdown of Ras gene expression by siRNA. Results The MAPK-ERK could be activated by both recombinant DMP1 C-terminal(rDMP1C) and full lenth(rDMP1F) from 5 min to 3 h in three cell lines. The phosphorylated-ERK increased, but not total ERK, in these cell lines treated by rDMP1. The phosphorylation of MAPK-ERK by rDMP1F in hMSC cells last longer than that in MC3T3 or MDPC-23 cells. The activation of MAPK lasted longer by rDMP1F than by rDMP1C. MAPK inhibitor could decrease the phosphorylation of MAPK-ERK by rDMP1C and rDMP1F and inhibit the ERK translocation from the cytoplasm into the nucleus. Knowdown of Ras gene expression by siRNA could significantly decrease the phosphoralated of ERK. Conclusion Both rDMP1C and rDMP1F can active the MEK-ERK, however, rDMP1F has a stronger effect in trigger MAPK signalling pathway than rDMP1C.