Dentin sialoprotein

The odontoblasts secrete an extracellular matrix that is rich in collagen I and which also contains all of the other major bone proteins as well as a dentin sialoprotein and poorly characterized phosphate carriers, the phosphophoryns. 

Bone and teeth are composed of hydroxyapatite crystals [16,17] and the crystal axis of both is controlled by organic matrices, such as collagens, acidic peptides and peptide-glucans [18-20]. The acidic peptide is called phosphoryn and contains repeated Asp-Ser-Ser sequences, of which the Ser residues are totally phosphorylated (Fig. 1) [21]. Similarly, large munbers of Glu, Asp and Ser residues are found in peptide-glucan and dentin sialoprotein. These proteins are known to be essential for the calcification of hydroxyapatite crystals [18]. 

MacDougall M. et aL 1997. Dentin phosphoprotein and dentin sialoprotein are cleavage products expressed from a single transcript coded by a gene on human chromosome 4. Dentin phosphoprotein DNA sequence determination. / Bio/ Chem 272(2) 835-842. 

Concerning dental tissues, the odontogenic differentiation of human dental pulp stem cells is demonstrated on nanofibrous PLA scaffolds, both in vitro and (following in vitro culture for two weeks in presence of inductive supplements) in vivo by dentin sialoprotein immunoistochemical staining performed two months post-implantation. " " ... 

Important molecules of this class are dentin phosphoryns or sialoproteins containing high aspartic acid (Asp) and extremely high serine (Ser) amoimts, which can be phosphorylated by the enzymes casein kinases I and II. Examples include rat dentin phosphoprotein with 43% Ser and 31% Asp [155], rat phosphoryn with 56% Ser and 32% Asp [ 156], hiunan dentin phosphophoryn with 58% Ser and 26% Asp [157] or a moUuscan shell glycoprotein with 32% Ser and 20% Asp [158]. It seems that phosphoserin (P-Ser) is of especial importance for polymer-crystal interactions, very Ukely in blocked sequences. In addition, the so-called Asprich proteins were recently identified in nacre and can contain up to 53 mol % Asp and 11% Glu [ 159,160]. 

A second category of NCPs with Ca-binding properties is classified as mineraUzed tissue specific, since they are found in all the calcified connective tissues, namely, dentin, bone, and cementum. These proteins include osteocalcin (OC) and bone sialoprotein (BSP). A serine-rich phosphoprotein called dentin matrix protein 1 (Dmp-1), whose expression was first described as being restricted to odontoblasts [5], was later shown to be expressed by osteoblasts and cementoblasts [6]. Other NCPs include osteopontin and osteonectin [secreted protein acidic and rich in cysteine (SPARC)]. The fourth category of dentin NCPs is not expressed in odontoblasts but is primarily synthesized in the liver and released... 

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