应力环境中sclerostin介导BMP2-Wnt"交互对话"调控成牙骨质细胞功能的机理研究

Cementoblasts are cementum-forming cells by secrete cemental matrix and then make it mineralized, which play an important role in the progress of root resorption and repair. Our previous studies found that mechanical strain can regulate the mineral-related function of cementoblasts, as well as the expression of BMP2 and sclerostin. Sclerostin is a certain antagonist of Wnt pathway, which can be regulated by BMP2. So the questions are raised that whether the sclerostin mediated "cross-talk" between BMP2 and Wnt signaling pathway exists in cementoblasts, and how the "cross-talk" mediated by sclerostin regulates the biological function of cementoblast under mechanical stimuli. Thus, the aim of this current study is to explore the mechanism of mechanical signal transduction via sclerostin-mediated BMP2-Wnt pathway crosstalk, by utilizing the immortalized cementoblastic cells (OCCM-30) in vitro, and establishing a rat tooth movement model in vivo. The morphological changes, proliferation, and levels of mRNA and protein will be detected by kinds of technologies. The conclusion may give us further knowledge about the mechanism of Orthodontically induced inflammatory root resorption (OIIRR), and propose new viewpoints on the OIIRR therapy.

成牙骨质细胞是形成和修复牙骨质的关键效应细胞。申请人研究发现，成牙骨质细胞的矿化相关功能受到力学信号调控，同时BMP2和sclerostin表达增强。sclerostin是Wnt通路的天然拮抗剂，可受到BMP2调控。那么成牙骨质细胞中是否存在BMP2和Wnt信号通路的交互对话？sclerostin是否是沟通该"对话"的关键枢纽？应力环境下成牙骨质细胞功能是否受到BMP2-Wnt交互作用的调控？因此，本课题拟结合体内、体外实验，在体外以永生化成牙骨质细胞样细胞OCCM-30为研究对象，体内实验建立大鼠正畸牙移动模型，以sclerostin为切入点，研究应力刺激下sclerostin介导的BMP2-Wnt通路间的"交互对话"，及其对细胞形态、增殖、mRNA及功能蛋白等不同水平的调控，深入研究应力对成牙骨质细胞生物学功能的调控，以期为揭示正畸导致的炎性牙根吸收（OIIRR）的发生机理带来突破。

成牙骨质细胞是形成和修复牙骨质的关键效应细胞，其矿化相关功能受到力学信号调控，同时BMP2和Sclerostin的表达增强。Sclerostin是Wnt通路的天然拮抗剂，可受到BMP2调控。本课题结合体内、体外实验，在体外以永生化成牙骨质细胞样细胞OCCM-30为研究对象，体内实验建立Axin2转基因小鼠正畸牙移动模型，以Sclerostin为切入点，研究应力刺激下Sclerostin介导的BMP2-Wnt通路间的“交互对话”，及其对细胞形态、增殖、mRNA及功能蛋白等不同水平的调控，深入研究应力对成牙骨质细胞生物学功能的调控。研究结果显示，应力可激活成牙骨质细胞中Wnt信号通路及下游成骨基因的表达，BMP2可通过Smad通路正向调控成牙骨质细胞中Sclerostin的表达，机械压应力可增强Sclerostin的表达，反之Sclerostin可抑制压应力环境中BMP/Smad信号通路的表达，但对Wnt信号通路的调控无明显影响。体内实验证实Wnt激活的局部微环境中Sclerostin的表达降低，同时发现Wnt信号通路中的相关因子Lef1主要在牙骨质表面细胞中表达，提示成牙骨质细胞为Wnt敏感细胞，受到Wnt信号通路的调控。同时Wnt信号通路与力学信号交互作用，使牙移动速度降低。Sclerostin介导的BMP2-Wnt通路间的“交互对话”受应力环境、作用时间、其它信号通路的影响，形成了错综复杂的网状关系结构。