Bronckers A L, D'Souza R N, Butler W T, Lyaruu D M, van Dijk S, Gay S, Wöltgens J H
Department of Oral Cell Biology, Academic Center of Dentistry, Vrije Universiteit, Amsterdam, The Netherlands.
Cell Tissue Res. 1993 May;272(2):237-47. doi: 10.1007/BF00302729.
A non-collagenous protein, extracted from rat incisor dentin, is a dentin sialoprotein (DSP). We examined immunohistochemically the developmental appearance and tissue distribution of DSP in 1 to 3-day-old rat molar and incisor tooth germs. The earliest staining for DSP was observed in newly differentiated odontoblasts. In more advanced stages, immunostaining for DSP gradually increased in pre-dentin, odontoblasts and dentin, and appeared in many cells of the dental papilla. In early stages of development before the breakdown of the dental basement membrane, pre-ameloblasts were also positive for DSP. This staining disappeared from the ameloblast cell body soon after deposition of the first layer of mineralized dentin. Radiolabelling of tooth matrix proteins with 14C-serine in vitro followed by immunoprecipitation and fluorography confirmed that DSP was synthesized by tooth-forming cells. The immunolocalization for DSP was different from that of either collagen type-I, osteocalcin or the amelogenins. Whereas collagen type-I and osteocalcin were restricted to the mesenchymal dental tissues, the amelogenins were detectable in both epithelial and mesenchymal dental cells and tissues at the epithelio-mesenchymal interface at early stages of development, prior to the onset of dentin mineralization. We conclude that DSP is expressed in and secreted by odontoblasts and some dental papilla cells from early stages of dentinogenesis onwards, i.e. later than type-I collagen, but before deposition of the first layer of mineralized dentin. In pre-mineralizing stages, some of the matrix proteins may be endocytosed from the pre-dentin by both cell types involved in the epithelio-mesenchymal interaction.
从大鼠切牙牙本质中提取的一种非胶原蛋白是牙本质涎蛋白（DSP）。我们用免疫组织化学方法研究了DSP在1至3日龄大鼠磨牙和切牙牙胚中的发育表现及组织分布。DSP最早的染色出现在新分化的成牙本质细胞中。在更晚期阶段，DSP在前期牙本质、成牙本质细胞和牙本质中的免疫染色逐渐增强，并出现在牙乳头的许多细胞中。在牙基底膜破裂前的发育早期阶段，前成釉细胞对DSP也呈阳性。在第一层矿化牙本质沉积后不久，这种染色就从成釉细胞体消失了。体外用14C-丝氨酸对牙基质蛋白进行放射性标记，随后进行免疫沉淀和荧光显影，证实DSP是由牙齿形成细胞合成的。DSP的免疫定位与I型胶原、骨钙素或釉原蛋白的免疫定位不同。I型胶原和骨钙素局限于间充质牙组织，而在牙本质矿化开始前的发育早期阶段，在上皮-间充质界面处，上皮和间充质牙细胞及组织中均可检测到釉原蛋白。我们得出结论，从牙本质形成的早期阶段起，即晚于I型胶原但在第一层矿化牙本质沉积之前，DSP在成牙本质细胞和一些牙乳头细胞中表达并分泌。在矿化前期阶段，一些基质蛋白可能被上皮-间充质相互作用中涉及的两种细胞类型从前期牙本质中内吞。
