title: Dentin sialoprotein and dentin phosphoprotein overexpression during amelogenesis.
abstract: The gene for dentin sialophosphoprotein produces a single protein that is post-translationally modified to generate two distinct extracellular proteins: dentin sialoprotein and dentin phosphoprotein. In teeth, dentin sialophosphoprotein is expressed primarily by odontoblast cells, but is also transiently expressed by presecretory ameloblasts. Because of this expression profile it appears that dentin sialophosphoprotein contributes to the early events of amelogenesis, and in particular to those events that result in the formation of the dentino-enamel junction and the adjacent "aprismatic" enamel. Using a transgenic animal approach we have extended dentin sialoprotein or dentin phosphoprotein expression throughout the developmental stages of amelogenesis. Overexpression of dentin sialoprotein results in an increased rate of enamel mineralization, however, the enamel morphology is not significantly altered. In wild-type animals, the inclusion of dentin sialoprotein in the forming aprismatic enamel may account for its increased hardness properties, when compared with bulk enamel. In contrast, the overexpression of dentin phosphoprotein creates "pitted" and "chalky" enamel of non-uniform thickness that is more prone to wear. Disruptions to the prismatic enamel structure are also a characteristic of the dentin phosphoprotein overexpressing animals. These data support the previous suggestion that dentin sialoprotein and dentin phosphoprotein have distinct functions related to tooth formation, and that the dentino-enamel junction should be viewed as a unique transition zone between enamel and the underlying dentin. These results support the notion that the dentin proteins expressed by presecretory ameloblasts contribute to the unique properties of the dentino-enamel junction.
authors: University of Southern California, School of Dentistry, Center for Craniofacial Molecular Biology, Los Angeles, California 90033, USA. paine@usc.edu
authors: Michael L
authors: ML
authors: Paine
authors: Wen
authors: W
authors: Luo
authors: Hong-Jun
authors: HJ
authors: Wang
authors: Pablo
authors: P
authors: Bringas
authors: Amanda Y W
authors: AY
authors: Ngan
authors: Vetea G
authors: VG
authors: Miklus
authors: Dan-Hong
authors: DH
authors: Zhu
authors: Mary
authors: M
authors: MacDougall
authors: Shane N
authors: SN
authors: White
authors: Malcolm L
authors: ML
authors: Snead
mesh_terms: D000566:Amelogenesis / Q000502:physiology*; D000595:Amino Acid Sequence; D000818:Animals; D015139:Blotting, Southern; D003743:Dental Enamel / Q000196:embryology / Q000378:metabolism / Q000648:ultrastructure; D016326:Extracellular Matrix Proteins; D018628:Gene Dosage; D006801:Humans; D007180:Incisor / Q000002:abnormalities / Q000473:pathology / Q000648:ultrastructure; D051379:Mice; D008822:Mice, Transgenic; D008963:Molar / Q000002:abnormalities / Q000473:pathology / Q000648:ultrastructure; D008969:Molecular Sequence Data; D010750:Phosphoproteins / Q000096:biosynthesis / Q000235:genetics*; D011498:Protein Precursors / Q000096:biosynthesis / Q000235:genetics*; D012795:Sialoglycoproteins; D000099311:Dentin Sialophosphoprotein
chemical_list: D016326:Extracellular Matrix Proteins; D010750:Phosphoproteins; D011498:Protein Precursors; D012795:Sialoglycoproteins; D000099311:Dentin Sialophosphoprotein; C017630:phosphophoryn