title: Leucine-rich amelogenin peptides regulate mineralization in vitro.
abstract: Amelogenin's capacity to regulate enamel formation is related to its conserved N- and C-terminal domains, its ability to self-assemble, and its ability to stabilize amorphous calcium phosphate (ACP) - a capacity enhanced by amelogenin phosphorylation. This in vitro study provides further insight into amelogenin function, using variations of the Leucine-Rich Amelogenin Peptide (LRAP), an alternative splice product comprised solely of amelogenin's N- and C-terminal domains. Peptide self-assembly was studied by dynamic light-scattering and transmission electron microscopy (TEM). TEM, selected area electron diffraction, and Fourier transform-infrared spectroscopy were also used to determine the effect of phosphorylated and non-phosphorylated LRAP on calcium phosphate formation. Results show that phosphorylated and non-phosphorylated LRAP can self-assemble into chain-like structures in a fashion dependent on the C-terminal domain. Notably, this capacity was enhanced by added calcium and to a much greater degree for phosphorylated LRAP. Furthermore, phosphorylated LRAP was found to stabilize ACP and prevent its transformation to hydroxyapatite (HA), while aligned HA crystals formed in the presence of non-phosphorylated LRAP. The N- and C-terminal amelogenin domains in non-phosphorylated LRAP are, therefore, sufficient to guide ACP transformation into ordered bundles of apatite crystals, making LRAP an excellent candidate for biomimetic approaches for enamel regeneration.
authors.affiliation: Department of Biomineralization, The Forsyth Institute, 245 First Street, Cambridge, MA 02142, USA.
authors.forename: E
authors.initials: E
authors.lastname: Le Norcy
authors.forename: S-Y
authors.initials: SY
authors.lastname: Kwak
authors.forename: F B
authors.initials: FB
authors.lastname: Wiedemann-Bidlack
authors.forename: E
authors.initials: E
authors.lastname: Beniash
authors.forename: Y
authors.initials: Y
authors.lastname: Yamakoshi
authors.forename: J P
authors.initials: JP
authors.lastname: Simmer
authors.forename: H C
authors.initials: HC
authors.lastname: Margolis
mesh_terms: D000566:Amelogenesis; D053523:Amelogenin / Q000737:chemistry; D000595:Amino Acid Sequence; D000818:Animals; D002130:Calcium Phosphates / Q000378:metabolism*; D003746:Dental Enamel Proteins / Q000737:chemistry* / Q000502:physiology*; D006863:Hydrogen-Ion Concentration; D057927:Hydrophobic and Hydrophilic Interactions; D046529:Microscopy, Electron, Transmission; D008969:Molecular Sequence Data; D053758:Nanoparticles; D010766:Phosphorylation; D017434:Protein Structure, Tertiary; D017550:Spectroscopy, Fourier Transform Infrared; D013552:Swine; D014074:Tooth Calcification / Q000502:physiology*
chemical_list: D053523:Amelogenin; D002130:Calcium Phosphates; D003746:Dental Enamel Proteins; C519480:amorphous calcium phosphate; C067432:leucine-rich amelogenin peptide