[Show abstract][Hide abstract] ABSTRACT: Proteoglycans and their constituent glycosaminoglycan (GAG) have been proposed to be involved in the inhibition of mineralization in unmineralized tissue, predentin. Among the proteoglycans secreted by odontoblasts, we focused on the large chondroitin sulfate proteoglycan, versican, for its large binding capacity for calcium ions. The aims of this study were the determination of the full-length sequence and splicing variants of the porcine versican, and the detection of versican in the porcine predentin. The complete coding sequence of the porcine versican mRNA was cloned to be 11,775 nucleotides long and encode 3,924 amino acids, and four splicing variants, V0, V1, V2 and V3, were characterized in the isolated porcine cartilage cells. The number of potential GAG attachment sites was 15 in the V0 variant, 13 in the V1 variant, 2 in the V2 variant and 0 in the V3 variant. They were deposited in DDBJ. The V1 variant was determined by RT-PCR in the odontoblasts, dental papilla cells, dental follicle cells, periodontal ligament cells, dental pulp cells, and gingival cells of pigs, although a small amount of the V0 valiant was found in the dental papilla cells. The predentin was prepared from developing porcine permanent incisor tooth germs and its soluble proteins were extracted in order to be partially characterized by protein and proteinase profiles. The versican V1 cleavage products were detected in the predentin extract by Western blotting analysis. These results suggested that the versican splice variant V1 implicates both the control of the mineralization and the activities of the predentin metalloproteinases, because it has 13 GAG chains that bind a large amount of calcium.
[Show abstract][Hide abstract] ABSTRACT: Objectives: The predentin, which is a precursor of dentin, should contain the control mechanism of calcification. As one mechanism, it is inferred that the large proteoglycan is related to the calcification mechanism. Versican is a large chondroitin sulfate proteoglycan and a major component of the extracellular matrix. It is a member of the aggrecan/versican proteoglycan family. This protein is involved in cell adhesion, proliferation, migration and angiogenesis and plays a central role in tissue morphogenesis and maintenance. Versican has 3 splice variants, designated V0, V1, and V2, which differ in the length of their glycosaminoglycan attachment portions inserted between the globular modules at the N- and C-terminal ends of the core proteins. Versican V1 and V2 include either the GAG-α or the GAG-β domain providing attachment sites for 5 to 8 or 12 to 15 glycosaminoglycan chains, respectively. In the V0 variant, both GAG-α and GAG-β are present. The presence of another splice variant, designated V3, lacks a glycosaminoglycan attachment region, the most distinctive portion of the proteoglycan molecule. Methods: and Results: We now describe the analysis of the amino acid sequence of the porcine versican revealed by the cDNA sequence of versican in the porcine odontoblast. In addition, expression profiling of the spliced variants in the deciduous teeth and the permanent tooth germ was completed. Conclusion: The results of these experiments suggest the variant of the versican in the porcine tooth predentin is used appropriately by the organization.