Cytodifferentiation activity of synthetic human enamel sheath protein peptides

Enamel sheath protein (ESP) is involved in the construction of the enamel sheath during tooth development. The 17 kDa ESP is a one-step cleavage product processed by proteolysis from the N-terminal side of sheathlin (ameloblastin/amelin), one of the porcine enamel matrix proteins. Enamel sheath protein exhibits periodontal ligament and cementum regeneration activity in a buccal dehiscence model in dogs, and promotes the cytodifferentiation of cultured human periodontal ligament (HPDL) cells. The aim of this study was to determine the peptide segment on the C-terminal side sequence of the human ESP that possesses a cytodifferentiation activity on cultured HPDL cells.

The peptides synthesized on the basis of human ESP C-terminal side sequence were tested for their ability to increase the alkaline phosphatase (ALP) and mineralization activity of cultured HPDL cells. The expressions of osteocalcin, osteopontin and bone sialoprotein were measured by semi-quantitative PCR and therefore were determined to be specific indicators of mineralized tissue differentiation.

Multiple synthetic peptides from the human ESP increased the ALP activity and stimulated matrix mineralization in long-term cultures of HPDL cells. Semi-quantitative PCR demonstrated the osteocalcin, osteopontin and bone sialoprotein expressions to increase relative to the control values. The peptide SDKPPKPELPGVDF had the strongest cytodifferentiation activity among all the synthetic peptides tested.

A specific peptide sequence derived from the C-terminal side of the human ESP promotes the cytodifferentiation and mineralization activity of HPDL cells in a cell culture system.