O-乙酰基葡萄糖修饰β-Catenin调控成骨分化的机制研究

O-GlcNacylation is an important protein modification, which has an important role in regulating protein structure, function and stability. Although researchers have just brought an attention to this area, its roles in bone are not well understood. Our previous studies found that (1) O-GlcNacylation occurs during the process of bone morphogenesis induced by bone morphogenetic proteins, resulting in the O-GlcNacylation modification of β-catenin, an important protein in the Wnt signaling pathway. This therby causes a negative feedback inhibition of osteogenic differentiation; (2) β-catenin at S33 and S37 are the key modification sites; (3) The osteogenic protein, NRAGE, promots O-GlcNacylation in bone morphogenesis. The present project intends to ultilize in vitro and in vivo approach to explore: (1) while β-catenin acts as an important protein in bone differentiation, what are the impact and the regulation of β-catenin O-GlcNacylation in bone formation; (2) what are molecular mechanisms for regulating β-catenin function by O-GlcNacylation; (3) what are molecular mechanisms for regulating the O-GlcNacylation of β-catenin by NRAGE. This project will contribute to the in-depth understanding of the relationship between the O-GlcNacylation and bone tissue differentiation/development and to the O-GlcNacylation-related regulation in the Wnt signaling pathway.

O-乙酰氨基葡萄糖（O-GlcNacylation, O-GlcNac）修饰是一种重要的蛋白修饰方式，在调节蛋白质的结构、功能与稳定性方面具有重要作用，但这方面的研究刚受重视，在成骨方面的作用尚为空白。我们前期研究发现：骨形成蛋白诱骨过程中启动O-GlcNac修饰，导致Wnt信号通路重要蛋白β-catenin的O-GlcNac修饰，负反馈抑制成骨分化；β-catenin的S33与S37是关键的修饰位点；成骨相关蛋白NRAGE促进上述现象的发生。本项目拟通过体内外研究探索：β-catenin作为骨分化中的重要蛋白，其O-GlcNac修饰对骨形成的调控作用；O-GlcNac修饰调控β-catenin功能的分子机制； NRAGE影响β-catenin的O-GlcNac修饰的分子机制。本项目的完成将有助于深入认识O-GlcNac修饰与骨组织分化发育的关系及其对Wnt信号途径的调控作用。

O-乙酰氨基葡萄糖（O-GlcNacylation, O-GlcNac）修饰是一种重要的蛋白修饰方式，在调节蛋白质的结构、功能与稳定性方面具有重要作用。本项目研究发现：骨形成蛋白诱骨过程中启动O-GlcNac修饰，导致Wnt信号通路重要蛋白β-catenin的O-GlcNac修饰，负反馈抑制成骨分化；β-catenin的S33与S37是关键的修饰位点；成骨相关蛋白NRAGE促进上述现象的发生。同时又着重研究了修饰酶OGT的作用：我们检测了基因敲除OGT（OGTKO）对骨骼和磷酸盐动态平衡的影响。与野生型（WT）同窝仔鼠相比，OGTKO小鼠没有表现矮小症状，而股骨和腰椎骨中的骨矿物质密度和骨矿物质含量显著增加。微型计算机断层扫描分析股骨显示，KO与WT相比由于小梁间距减小，骨小梁的体积，厚度，数量和结缔组织密度增加。本研究的工作充分证明了O-乙酰氨基葡萄糖基化修饰对成骨过程的调控作用。