Effects of Amalogenin Peptides on Human Periodontal Ligament Cells

Objective: It has been reported that the developing enamel matrix has the biological activity of inducing osteogenesis and cementgenesis. Amlogenin and its derivatives comprise up to 90% of the developing enamel matrix proteins, but the biological activity of the amalogenin has not been understood. The purpose of this study was to examine the biological activity of amelogenin and its derived proteins on periodontal cell differentiation and identify the active amino acid sequence of amelogenin.

Methods: Amelogenin and its derivatives (6kDa, 20kDa, 25kDa) containing the N-terminal sequence were purified from porcine immature enamel extracts, and several small peptides in the N-terminal region were synthesized on the basis of the porcine amalogenin sequence. Healthy human periodontal ligament (HPDL) cells were used to study the biological activities of the amelogenin derived proteins and synthetic peptides. HPDL cells were exposed to the amelogenin samples, and then examined their alkaline phosphatase (ALP) activity, mitogenic activity using the MTT assay, biomineralization activity and gene expressions of the differentiation marker protein using RT-PCR were evaluated.

Results: The 6kDa amelogenin derivative and the synthetic oligopeptides containing the N-terminal sequence had greater activities than other amelogenin samples in the ALP induction of the HPDL cells. There was no mitogenic activity in these peptides. At that time it was confirmed that the expression of the bone sialoprotein (BSP) as a differentiation marker increased. The peptides stimulated the biomineralization in the long term culture of the HPDL cells.

Conclusion: The results indicated that the N-terminal side of the porcine amelogenin accelerated the cytodifferentiation activity of the HPDL cells.