Notch关键靶点Hey1调控BMP诱导干细胞成骨分化的作用机制研究

Bone defect and nonunion was a major problem in the orthopaedic clinic work. Tissue engineering technology in clinically repairing damaged bones has wide application prospects. BMPs induced osteogenesis of the mesenchymal stem cells to promote bone repairing and the reconstruction is the hot spot of regenerative medicine research .We previously demonstrated that BMPs are able to induce osteogenic differentiation of MSCs both in vitro and in vivo. Although the original vascularized bone tissue induced by BMPs was confirmed in the animal, the mechanism of BMPs promoting mesenchymal stem cells to differentiate into the bone tissue was not yet clear, and still need to continue to study. Here, we conducted gene expression-profiling analysis and identified that Hey1 of the hairy/Enhancer of splitrelated repressor protein basic helix-loop-helix family was among the most significantly up-regulated early targets in BMP-stimulated MSCs. In view of Hey1 genes also as key target of Notch signaling pathways regulating the proliferation and differentiation of stem cells , as well as with BMPs signal network Smads/MAPKs connection. So the research Hey1 gene regulating the BMPs induced osteogenesis will be helpful to the further understanding of bone differentiation mechanism.

骨缺损、骨不连和骨折延迟愈合一直是困扰骨科临床工作的难题，利用组织工程学技术修复骨组织在临床上具有广阔的应用前景。其中骨形态发生蛋白BMPs诱导间充质干细胞的成骨分化、促进骨组织修复和重建是当今再生医学研究的热点。虽然动物试验已证实BMPs在体内诱导出高度血管化的原始骨组织，并已应用于前期临床试验，但是人们对BMPs诱导间充质干细胞骨向分化的机制尚未明了，仍需继续深入研究。而我们的前期研究发现，发状分裂相关增强子Hey1作为BMPs信号系统的靶基因，在间充质干细胞中其表达水平能被多种有骨向诱导能力的BMPs上调。鉴于Hey1基因同时作为Notch信号通路的关键靶点，在调节干细胞分化和增殖中的重要作用，以及与BMPs信号网络Smads/MAPKs之间的联系，因此进一步研究Hey1基因调控BMPs骨向诱导机制，有助于深入理解骨分化机制，从而为临床上骨组织修复、重建提供理论依据和实验基础。

骨缺损、骨不连和骨折延迟愈合一直是困扰骨科临床工作的一项难题，而利用组织工程学技术修复骨缺损、骨不连在临床上愈来愈具有广阔的应用前景。其中骨形态发.生蛋白BMPs诱导间充质干细胞的成骨分化、促进骨组织修复和重建是当今组织工程医学研究的热点。但BMP诱导间充质干细胞成骨分化的调控机制并不十分明确，前期我们发现发状分裂相关增强子Hey1基因与BMPs诱导的干细胞骨向分化密切相关，Hey1基因在分化早期表达增加，促进了细胞增殖并抑制MSCs的骨分化，因此进一步探究BMP与Hey1在调控成骨分化过程中的协同作用是有必要的。我们发现在BMP9诱导间充质干细胞分化过程中，过表达Hey1能协同增强其促成骨作用，且能增强其增殖能力，反之，在BMP9诱导的成骨过程中抑制Hey1的表达后，明显降低了BMP9的促成骨作用，同样抑制了间充质干细胞的增殖能力。在体内动物实验中,通过活体荧光成像我们发现过表达Hey1基因明显增强其BMP成骨能力，表现为裸鼠皮下骨块较对照组明显增加，反之则抑制Hey1其骨块形成。..因此进一步研究Hey1基因协同调控BMP9骨向诱导机制，有助于深入理解骨分化机制，从而为临床上骨组织修复、重建寻求新的药物靶点提供理论依据和实验基础。