Characterization of factors controlling the differentiation of periodontal ligament cells

本研究的目的是表征控制牙周韧带（PDL）细胞分化和功能的分子。构建了牛PDL组织cDNA文库，克隆了钙结合蛋白S100A4的cDNA。我们观察到S100A4 mRNA在突牙PDL中的表达水平较高，并且PDL细胞分泌该蛋白，该蛋白位于胶原纤维附近。在成骨细胞培养中加入重组S100A4蛋白抑制矿化。在培养中，机械应力作用下的PDL细胞增加了S100A4 mRNA和细胞骨架蛋白的表达。尽管该蛋白在MC3T3-E1细胞（成骨细胞）中的表达水平较低，但抑制MC3T3-E1细胞中S100A4的表达可刺激培养中的矿化。这些结果强烈表明S100A4是PDL组织中mermerization的抑制剂。另一方面，猪牙釉质基质衍生物（EMD）刺激牛PDL细胞和小鼠骨髓库萨细胞的生长和分化，从而刺激这些细胞的矿化。对成骨细胞的刺激作用也有助于牙周组织的再生。阐明EMD和库萨细胞中的有效分子对研究有重要意义。猪重组淀粉原蛋白刺激了库萨细胞的分化，表明淀粉原蛋白可能是有效分子。虽然还需要进一步的研究，但我们可以将重组淀粉原蛋白应用于牙周组织再生。

The purpose of this research was to characterize molecules which control the differentiation and function of periodontal ligament (PDL) cells. We constructed cDNA library of bovine PDL tissue and cloned cDNA of S100A4, one of the calcium binding proteins. We observed that mRNA expression level of S100A4 in PDL of erupted teeth was high and that PDL cells secreted this protein, which localized adjacent to collagen fibers. Addition of recombinant S100A4 protein to oseteoblastic culture inhibited mineralization. In culture, PDL cells under mechanical stress inceased mRNA expression of S100A4 together with cytoskeletal proteins. Although the expression level of this protein in MC3T3-E1 cells (osteoblastic cells) was low, inhibition of S100A4 expression in MC3T3-E1 cells stimulated mineraliztion in culture. These results strongly indicate that S100A4 is an inhibitor of meranlization in PDL tissue. On the other hand, porcine enamel matrix derivative (EMD) stimulated growth and differentiation of bovine PDL cells and Kusa cells (derived from mouse bone marrow), resulting the stimulation of mineralization in these culture. The stimulatory effects on osteoblastic cells could also contribute to periodontal tissue regeneration. It is important to clarify effective molecule (s) in EMD and Kusa cells are useful for this investigation. Porcine recombinant amelogenin stimulated the differentiation of Kusa cells indicating the possibility that amelogenin is the effective molecule.Although further studies are necessary, we could apply recombinant amelogenin to periodontal tissue regeneration.