Abstract: Abstract: Objective To investigate the effects of BMP2 and BMP4 on the expression of matrix metalloproteinase 20 (MMP20) and kallikrein 4 (KLK4) in ALC (ameloblast-lineage cell). Methods Recombinant proteins of BMP2 and BMP4 were added to ALC cell lines, and changes in BMP pathway signaling and enamel matrix protease expression were detected by Western blot and real-time PCR. At the same time, another group of cells was treated with a BMP pathway inhibitor（Dorsomorphin, Dor）to detect the expression of enamel matrix proteases. Results Under the action of BMP2 and BMP4 proteins, the expression of classical pathway（Smad1/5/8）and non-classical pathway（p38）of BMP pathway in ALC cells was significantly enhanced, and the expression of MMP20 and KLK4 genes was also significantly up-regulated. In the same period, the expression of the classical pathway of BMP pathway in ALC cells with Dorsomorphin was significantly decreased, while the expression of the non-classical pathway was not significantly changed, and the expression of MMP20 and KLK4 genes also showed a significant down-regulation trend. In another set of experiments, the treatment group with BMP inhibitor showed down-regulation of MMP20 and KLK4 protein expression, while the rescue group treated with BMP2 and BMP4 showed significant recovery of MMP20 and KLK4 protein levels. Conclusions BMP2 and BMP4 can regulate the expression of enamel matrix protease during tooth enamel formation by influencing the BMP classical pathway.

Key words: bone morphogenetic protein2, bone morphogenetic protein4, metalloproteinase 20, kallikrein 4