Department of Developmental Dentistry, the University of Texas Health Science Center at San Antonio, San Antonio, Texas, 78229-3700, United States.
Department of Pathology, Weifang Medical University, Weifang, Shandong Province, 261053, China.
Sci Rep. 2017 Mar 22;7(1):300. doi: 10.1038/s41598-017-00339-w.
Dentin sialoprotein (DSP) is a dentin extracellular matrix protein. It is involved in dental mesenchymal cell lineages and dentin formation through regulation of its target gene expression. DSP mutations cause dentin genetic diseases. However, mechanisms of DSP in controlling dental mesenchymal cell differentiation are unknown. Using DSP as bait, we screened a protein library from mouse odontoblastic cells and found that DSP is a ligand and binds to cell surface receptor, occludin. Further study identified that the C-terminal DSP domain interacts with the occludin extracellular loop 2. The C-terminal DSP domain induced phosphorylation of occludin Ser and focal adhesion kinase (FAK) Ser and Tyr. Coexpression of DSP, occludin and FAK was detected in dental mesenchymal cells during tooth development. Occludin physically interacts with FAK, and occludin and FAK phosphorylation can be blocked by DSP and occludin antibodies. This DSP domain facilitates dental mesenchymal cell differentiation and mineralization. Furthermore, transplantation and pulp-capping procedures revealed that this DSP domain induces endogenous dental pulp mesenchymal cell proliferation, differentiation and migration, while stimulating blood vessel proliferation. This study elucidates the mechanism of DSP in dental mesenchymal lineages and implies that DSP may serve as a therapeutic agent for dentin-pulp complex regeneration in dental caries.
牙本质涎磷蛋白（DSP）是牙本质细胞外基质蛋白。它通过调控靶基因表达参与牙间充质细胞谱系和牙本质形成。DSP 突变导致牙本质遗传性疾病。然而，DSP 控制牙间充质细胞分化的机制尚不清楚。我们以 DSP 为诱饵，从小鼠成牙本质细胞的蛋白文库中进行筛选，发现 DSP 是一种配体，与细胞表面受体紧密连接蛋白（occludin）结合。进一步的研究确定 DSP 的 C 末端结构域与 occludin 的胞外环 2 相互作用。DSP 的 C 末端结构域诱导 occludin 的 Ser 和 focal adhesion kinase（FAK）的 Ser 和 Tyr 磷酸化。在牙齿发育过程中，牙间充质细胞中检测到 DSP、occludin 和 FAK 的共表达。occludin 与 FAK 发生物理相互作用，DSP 和 occludin 抗体可以阻断 occludin 和 FAK 的磷酸化。该 DSP 结构域促进牙间充质细胞的分化和矿化。此外，移植和盖髓术实验表明，该 DSP 结构域诱导内源性牙髓间充质细胞增殖、分化和迁移，同时刺激血管增殖。本研究阐明了 DSP 在牙间充质细胞谱系中的作用机制，并提示 DSP 可能作为牙本质牙髓复合体再生治疗龋齿的一种药物。
