Differential Expression of Non-collagenous Proteins in Developing Rat Teeth

Objective: The non-collagenous proteins (NCPs) are believed to control initiation and growth of the crystals in developing teeth. Dentin contains three major proteins: dentine phosphoryn (DPP), dentine sialoprotein (DSP) and dentine matrix protein (Dmp1). The matrix of enamel is composed of amelogenins, amelo-blastin, enamelins and tuftelin. Methods: In this paper, we studied the pattern of expression of five NCPs (DPP, DSP, Dmp1, amelogenin and ameloblastin) during the development of rat teeth by immunohisto-chemistry and in situ hybridization. Results: Our results show that the expression of these NCPs has temporally and spatially difference. Polarized ameloblasts start to accumulate amelogenin, followed by the amelo-blastin gene expression in mature ameloblasts. They also express in pre-odontoblasts. Dmp1, DSP and DPP show co-expression in young odontoblasts before the start of mineralization. Then Dmp1 expression decreased in secretory odontoblasts, while high levels of DSP and DPP are sustained in odontoblasts. These dentin NCPs also express in early secretory ameloblasts. Conclusion: These data indicate that the developmental expression patterns of the five NCPs are distinct, implying that these proteins serve different biological functions in dental hard tissue mineralization.