Effect of Human Amelogenin on the Proliferation of Periodontal cells

Objectives: Amelogenins are major enamel matrix proteins (EMPs) synthesized by ameloblasts. Resent studies suggest that EMPs contribute to periodontal tissue regeneration as well as amelogenesis. It is assumed that amelogenin may affect the metabolism of periodontal ligament (PDL) cells and cementoblasts. However, the detailed effects of amelogenins on periodontal cells still remain unclear. The purpose of this study was to examine the effects of full-length amelogenin on the proliferation of periodontal cells. Materials and methods: Human PDL (HPDL) cells and human oral keratinocyte (HOK) cells were cultured and treated with 0.01~10 µg/ml recombinant human full-length amelogenin (rh174) in the presence or absence of anti-CD63 antibody. The cell proliferation was evaluated by use of a cell proliferation ELISA BrdU kit and MTT method. In addition, the activity of extracellular signal regulated kinases (ERK)1/2 was measured by means of a Cellular Activation of Signaling ELISA Kit. Results: Proliferation of HPDL cells was enhanced significantly by the treatment with rh174, and inhibited by the addition of anti-CD63 blocking antibody. In addition, the activity of phospho/ERK1/2 signaling of the HPDL was enhanced significantly by the treatment with rh174 as compared to the control group, and inhibited by the addition of CD63 blocking antibody. Meanwhile, the proliferation of HOK cells was not enhanced significantly by the treatement with rh174. Conclusions: From these results, it is suggested that CD63 is a receptor of rh174 in HPDL cells, and that CD63/rh174 interaction activates the signaling pathway of ERK1/2, resulting in the increased proliferation of HPDL cells. It is highly anticipated that amelogenin may contribute to the cell proliferation of HPDL cells, leading to the regeneration of periodontal tissue.