Cytodifferentiation activity of synthesized human enamel seath protein peptides

Objectives: We have shown that the real enamel protein component having the cementum regeneration activity, one aspect of the periodontal ligament regeneration activity in the experimental cavity created on a buccal dehiscence model in dogs, is the enamel sheath protein when using porcine enamel proteins. This activity is found in the 17-kDa sheath protein, but not in the 15-kDa sheath protein which has no carboxy (C) terminal side extra peptide. The aim was to determine the peptide having the cytodifferentiation activity, which was effective for the cementum regeneration activity, in the sheath protein C-terminal side sequence on the cell culture system. Methods: Five synthetic peptides were prepared on the basis of the human enamel sheath protein C-terminal extra peptide sequence that consisted of 65 amino acids and tested for an increase in the alkaline phosphatase activity, revealed the cytodifferentiation activity, in the cell culture system of human periodontal ligament (HPDL) cells. Their mineralization activity was tested in a long term cell culture and the expression of osteocalcin, osteopontin and bone sialoprotein (BSP) as the specific indicators of the cytodifferentiation activity were examined by RT-PCR. Results: Although multiple synthetic peptides increased the ALP activity of the HPDL cells, the peptide SDKPPKPELPVDF had the strongest activity of five in the cell culture system. The peptide stimulated the mineralization during the long-term cultured matrix of the HPDL cells. At that time, it was confirmed from the RT-PCR results that the expressions of osteopontin, osteocalcin and BSP had increased. Conclusion: The results indicated that the SDKPPKPELPVDF, one of the peptides synthesized on the basis of the human enamel sheath protein sequence, accelerated the cytodifferentation activity of HPDL cells in the cell culture system.