Division of Anatomy and Cell Biology of the Hard Tissue, Department of Tissue Regeneration and Reconstruction, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan.
Division of Anatomy, Department of Health Promotion, Kyushu Dental University, Kitakyushu, Japan.
J Endod. 2020 Jan;46(1):89-96. doi: 10.1016/j.joen.2019.10.002. Epub 2019 Nov 15.
Although dentin matrix protein 1 (DMP1) and osteopontin (OPN) act as substrates and signaling molecules for odontoblastlike cell differentiation after tooth injury, the mutual interaction between these proteins in the mechanism of odontoblastlike cell differentiation remains to be clarified. This study aimed to elucidate the role of DMP1 and OPN in regulating odontoblastlike cell differentiation after tooth injury.
A groove-shaped cavity was prepared on the mesial surface of the upper first molars in wild-type and Opn knockout (KO) mice. The demineralized paraffin sections were processed for immunohistochemistry for nestin and DMP1 and in situ hybridization for Dmp1. For the in vitro assay, the experiments of organ culture for evaluating dentin-pulp complex regeneration using small interfering RNA treatment were performed.
Once preexisting odontoblasts died, nestin-positive newly differentiated odontoblastlike cells were arranged along the pulp-dentin border and began to express DMP1/Dmp1. In Opn KO mice, the expression of DMP1/Dmp1 was up-regulated compared with that of wild-type mice. The in vitro assay showed that the gene suppression of Dmp1 by small interfering RNA showed a tendency to decrease the differentiation rate of odontoblastlike cells from 70.1% to 52.2% in wild-type teeth. In addition, the suppression of Dmp1 in Opn KO teeth tended to lead to the inhibition of odontoblastlike cell differentiation.
These results suggest that the expression of Dmp1 is up-regulated in Opn KO mice both in vivo and in vitro, and DMP1 compensates for the lack of OPN in regulating odontoblastlike cell differentiation after tooth injury.
尽管牙本质基质蛋白 1（DMP1）和骨桥蛋白（OPN）在牙损伤后作为成牙本质细胞样细胞分化的底物和信号分子起作用，但这些蛋白在成牙本质细胞样细胞分化机制中的相互作用仍有待阐明。本研究旨在阐明 DMP1 和 OPN 在调节牙损伤后成牙本质细胞样细胞分化中的作用。
在上颌第一磨牙的近中面制备槽形腔。对脱矿石蜡切片进行巢蛋白和 DMP1 的免疫组织化学染色和 Dmp1 的原位杂交。对于体外试验，使用小干扰 RNA 处理进行了评估牙髓复合体再生的器官培养实验。
一旦预先存在的成牙本质细胞死亡，巢蛋白阳性的新分化的成牙本质细胞样细胞沿着牙髓牙本质边界排列，并开始表达 DMP1/Dmp1。在 Opn KO 小鼠中，与野生型小鼠相比，DMP1/Dmp1 的表达上调。体外试验表明，小干扰 RNA 对 Dmp1 的基因抑制使野生型牙齿中成牙本质细胞样细胞的分化率从 70.1%下降至 52.2%。此外，在 Opn KO 牙齿中抑制 Dmp1 倾向于抑制成牙本质细胞样细胞分化。
这些结果表明，Dmp1 的表达在体内和体外的 Opn KO 小鼠中均上调，并且 DMP1 补偿了 OPN 在调节牙损伤后成牙本质细胞样细胞分化中的缺失。
