scholarly journals Tooth Enamel Proteins Enamelin and Amelogenin Cooperate To Regulate the Growth Morphology of Octacalcium Phosphate Crystals

2010 ◽  
Vol 10 (11) ◽  
pp. 4815-4822 ◽  
Author(s):  
Mayumi Iijima ◽  
Daming Fan ◽  
Keith M. Bromley ◽  
Zhi Sun ◽  
Janet Moradian-Oldak
Keyword(s):  
Tooth Enamel ◽  
Octacalcium Phosphate ◽  
Growth Morphology ◽  
Enamel Proteins

Relative Levels of mRNA Encoding Enamel Proteins in Enamel Organ Epithelia and Odontoblasts

2003 ◽  
Vol 82 (12) ◽  
pp. 982-986 ◽  
Author(s):  
T. Nagano ◽  
S. Oida ◽  
H. Ando ◽  
K. Gomi ◽  
T. Arai ◽  
...  
Keyword(s):  
Tooth Enamel ◽  
Structural Proteins ◽  
Enamel Organ ◽  
Maturation Stage ◽  
Mrna Levels ◽  
Rt Pcr ◽  
Enamel Protein ◽  
Enamel Proteins ◽  
Enamel Layer

Amelogenin, enamelin, sheathlin (ameloblastin/ amelin), enamelysin (MMP-20), and KLK4 (EMSP-1) are the major structural proteins and proteinases in developing tooth enamel. Recently, odontoblasts were reported to express amelogenin, the most abundant enamel protein. In this study, we hypothesized that odontoblasts express all enamel proteins and proteases, and we measured their relative mRNA levels in enamel organ epithelia and odontoblasts associated with porcine secretory- and maturation-stage enamel by RT-PCR, using a LightCycler instrument. The results showed that amelogenin mRNA in secretory-stage EOE is 320-fold higher than in odontoblasts beneath secretory-stage enamel, and over 20,000-fold higher than in odontoblasts under maturation-stage enamel. Similar results were obtained for enamelin and sheathlin. Enamelysin mRNA levels were equivalent in these two tissues, while KLK4 mRNA was higher in odontoblasts than in secretory-stage EOE. These results support the conclusion that odontoblasts are involved in the formation of the enamel layer adjacent to enamel-dentin junction.

scholarly journals Molecular Mechanisms of Dental Enamel Formation

1995 ◽  
Vol 6 (2) ◽  
pp. 84-108 ◽  
Author(s):  
J.P. Simmer ◽  
A.G. Fincham
Keyword(s):  
Molecular Mechanisms ◽  
Tooth Enamel ◽  
Dental Enamel ◽  
Calcium Hydroxyapatite ◽  
Octacalcium Phosphate ◽  
Growth Patterns ◽  
Degree Of Saturation ◽  
Crystal Habit ◽  
Supersaturated Solution ◽  
Unit Cells

Tooth enamel is a unique mineralized tissue in that it is acellular, is more highly mineralized, and is comprised of individual crystallites that are larger and more oriented than other mineralized tissues. Dental enamel forms by matrix- mediated biomineralization. Enamel crystallites precipitate from a supersaturated solution within a well-delineated biological compartment. Mature enamel crystallites are comprised of non-stoichiometric carbonated calcium hydroxyapatite. The earliest crystallites appear suddenly at the dentino-enamel junction (DEJ) as rapidly growing thin ribbons. The shape and growth patterns of these crystallites can be interpreted as evidence for a precursor phase of octacalcium phosphate (OCP). An OCP crystal displays on its (100) face a surface that may act as a template for hydroxyapatite (OHAp) precipitation. Octacalcium phosphate is less stable than hydroxyapatite and can hydrolyze to OHAp. During this process, one unit cell of octacalcium phosphate is converted into two unit cells of hydroxyapatite. During the precipitation of the mineral phase, the degree of saturation of the enamel fluid is regulated. Proteins in the enamel matrix may buffer calcium and hydrogen ion concentrations as a strategy to preclude the precipitation of competing calcium phosphate solid phases. Tuftelin is an acidic enamel protein that concentrates at the DEJ and may participate in the nucleation of enamel crystals. Other enamel proteins may regulate crystal habit by binding to specific faces of the mineral and inhibiting growth. Structural analyses of recombinant amelogenin are consistent with a functional role in establishing and maintaining the spacing between enamel crystallites.

Amelogenin Nanospheres Modulate Crystal Habit of Octacalcium Phosphate and Hydroxyapatite Crystals in In Vitro Model Systems

2000 ◽  
Vol 620 ◽  
Author(s):  
Moradian-Oldak J. ◽  
Wen H.B. ◽  
Fincham A.G. ◽  
Iijima M.
Keyword(s):  
Membrane System ◽  
Octacalcium Phosphate ◽  
Model Systems ◽  
Crystal Habit ◽  
Width Ratio ◽  
Growth Morphology ◽  
Oriented Growth ◽  
Apatite Crystals

ABSTRACTThis paper is a short review of recent studies, which were undertaken to investigate interactions of amelogenin with octacalcium phosphate (OCP), and apatite. OCP crystals were grown using two independent experimental systems; (a) in a 10% gelatin gel, containing 0-2% amelogenin, where the crystals were formed in a double-diffusion chamber, and (b) in a 10% pure amelogenin gel, where crystal growth took place in between a cation-selective and a dialysis membrane. Apatite crystals were grown from a supersaturated calcifying solution on a bioactive glass in the absence (SCSB) and the presence of amelogenin (SCSrM179). It was found that OCP crystals formed in 10% gelatin gel containing 1-2% amelogenin were longer (3-5 times larger in aspect ratio) than the OCP crystals formed in 10% gelatin without amelogenin. A profound effect was that found in the cation selective membrane system when 10% amelogenin inhibited the growth morphology in a specific manner. Affected crystals had a length to width ratio twice larger than that of control crystals while the width to thickness ratio was about 1/12 of that of the control crystals. Amelogenin promoted the formation of bundles of lengthwise apatite crystals, which were all oriented parallel to their c axes when grown on SCSrM179. It was found that individual apatite crystals within those bundles adopted an elongated, curved shape. The data presented here suggest that amelogenin nanospheres modulate the growth morphology of apatite and OCP crystals and indicate significant functional roles for amelogenin proteins during the in vivo oriented growth of enamel crystallites.

scholarly journals Biosynthesis and characterization of rabbit tooth enamel extracellular-matrix proteins

1988 ◽  
Vol 251 (3) ◽  
pp. 631-641 ◽  
Author(s):  
M Zeichner-David ◽  
J Vides ◽  
M MacDougall ◽  
A Fincham ◽  
M L Snead ◽  
...  
Keyword(s):  
Extracellular Matrix ◽  
Tooth Enamel ◽  
Mammalian Species ◽  
Mrna Translation ◽  
Extracellular Matrix Proteins ◽  
Matrix Proteins ◽  
Lower Vertebrates ◽  
Enamel Proteins ◽  
Terminal Amino

Tooth enamel biomineralization is mediated by enamel proteins synthesized by ameloblast cells. Two classes of proteins have been described: enamelins and amelogenins. In lower vertebrates the absence of amelogenins is believed to give rise to aprismatic enamel; however, rabbit teeth, which apparently do not synthesize amelogenins, form prismatic enamel. The present study was designed to characterize the enamel proteins present in rabbit tooth organs and to gain an insight into the process of biomineralization. Rabbit enamel extracellular-matrix proteins were isolated and characterized during sequential stages of rabbit tooth organogenesis. The biosynthesis of enamel proteins was analysed by metabolic ‘pulse-chase’ experiments as well as mRNA-translation studies in cell-free systems. Our results indicated that rabbit enamel extracellular matrix contains ‘amelogenin-like’ proteins. However, these proteins are not synthesized as typical amelogenins, as in other mammalian species, thus suggesting that they are the processing products of higher-molecular-mass precursors. An N-terminal amino acid sequence of 29 residues, considered characteristic of mammalian amelogenins, was present in the rabbit ‘amelogenin-like’ proteins. By using anti-peptide antibodies to this region, similar epitopes were detected in all nascent enamel proteins, including enamelins. These studies suggest that the N-terminal sequence might be characteristic of all enamel proteins, not only amelogenins.

Production of a monoclonal antibody to bovine tooth enamel proteins

1983 ◽  
Vol 28 (8) ◽  
pp. 773-779 ◽  
Author(s):  
P.J. Christner ◽  
E.T. Lally ◽  
A.H. Ads ◽  
R.C. Herold
Keyword(s):  
Monoclonal Antibody ◽  
Tooth Enamel ◽  
Enamel Proteins

Effects of F- on apatite-octacalcium phosphate intergrowth and crystal morphology in a model system of tooth enamel formation

1992 ◽  
Vol 50 (4) ◽  
pp. 357-361 ◽  
Author(s):  
Mayumi Iijima ◽  
Hisako Tohda ◽  
Hiroshi Suzuki ◽  
Takaaki Yanagisawa ◽  
Yutaka Moriwaki
Keyword(s):  
Crystal Morphology ◽  
Tooth Enamel ◽  
Octacalcium Phosphate ◽  
Model System ◽  
Enamel Formation

Electron Microscopy Analysis of the Central Dark Line Defect of the Human Tooth Enamel

2004 ◽  
Vol 839 ◽  
Author(s):  
A. G. Rodríguez-Hernández ◽  
M.E. Fernández ◽  
G. Carbajal-De-La-Torre ◽  
R. García-García ◽  
J. Reyes-Gasga
Keyword(s):  
Tooth Enamel ◽  
Thick Layer ◽  
Octacalcium Phosphate ◽  
Human Tooth ◽  
Dark Line ◽  
Human Tooth Enamel ◽  
Electron Microscopy Analysis ◽  
Microscopy Analysis ◽  
Z Contrast ◽  
Microscopy Techniques

ABSTRACTAfter some experimental results that indicated that HA is able to growth in an epitaxial way on the surface of OCP, it has been suggested that the central dark line (CDL) observed in the nanometric-sized grains of human tooth enamel corresponds to a one-unit-cell-thick layer of octacalcium phosphate (OCP). Based on this consideration, in this work we propose a model for CDL and we carried out the chemistry and structural analysis of the CDL with high resolution microscopy techniques such as Electron Energy Loss Spectroscopy (EELS) and Z-contrast (HAADF) with the aim of find the agreements and/or differences between the human tooth enamel HA and its CDL.

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