PPR/IP3R3抑制骨髓间充质干细胞凋亡调控骨改建的机制研究

骨改建的动态平衡是维持口腔颌面部骨结构与功能的基础，颌骨骨髓间充质干细胞(OMSCs)在骨改建中发挥重要作用。申请人前期构建OMSCs特异性甲状旁腺激素1型受体(PPR)敲除小鼠，发现PPR敲除导致细胞凋亡增加，成骨细胞数量减少引起突变鼠骨量降低。高通量转录组测序发现突变鼠Itpr3基因升高。该基因编码IP3R3蛋白，负责调控内质网钙离子释放，可能与细胞凋亡相关，但在骨组织中尚未报道。据此，本课题提出科学假设：PPR通过负调控IP3R3抑制OMSCs凋亡，进而影响颌骨改建平衡。本项目拟通过干扰PPR通路明确PPR对IP3R3的负调控作用；调控PPR/IP3R3表达探索其对OMSCs凋亡的作用机制；并构建PPR和IP3R3双基因条件性敲除小鼠及建立颌骨缺损模型，分析PPR/IP3R3在骨改建中的作用。研究结果将丰富颌面部骨改建理论，为颌面部骨缺损修复提供新思路。

The dynamic balance of bone remodeling, which is largely regulated by the proliferation and apoptosis of the bone marrow mesenchymal stem cells (MSCs), is critical for maintaining the structure and function of orofacial bone. The applicant constructed mice with conditional deletion of parathyroid hormone type 1 receptor (PPR) in OMSCs, finding that apoptotic cells accumulated in the mandibular bone marrow, and the bone mass decreased in mutant. RNA sequencing technology excavated differentially expressed genes, and found that the expression of Itpr3 increased. Itpr3 encoded IP3R3, which can release calcium from endoplasmic reticulum and may participate in apoptosis. However, the role of IP3R3 in bone tissue has not been explored. Therefore, we hypothesize that PPR inhibits the apoptosis of OMSCs by negatively regulating expression of IP3R3, and thus plays a role in bone remodeling. We will probe the negative regulatory effect of PPR on IP3R3 by means of activation PPR signaling; explore the regulatory role of PPR/IP3R3 in apoptosis through disturbing expression of PPR/IP3R3; and reveal the importance of PPR/IP3R3 in bone remodeling by transgenic mice. Our results will enrich the theory of orofacial bone reconstruction, and provide new ideas and guidance for the repair and reconstruction of orofacial bone defects.