MCU调控线粒体动力学对糖尿病种植体骨结合的影响及机制研究

Diabetes is a recognized high risk factor for the osseointegration of dental implants. As the balance of mitochondrial dynamics is critical for cellular functions, impaired mitochondrial dynamics (excessive mitochondrial fission) have been found as an important characteristic for diabetic related bone injury. Recent studies highlighted the role of MCU in the regulation of mitochondrial dynamics, however, the underlying mechanisms remains to be further investigated. Although it is evidenced that MCU mediated Ca2+ signaling regulated osteoblast energetic metabolism signaling pathway, whether MCU regulates mitochondrial dynamics in osteoblasts or bone remains unclear. In our previous study, we found under high glucose treatment, MCU was greatly up-regulated in osteoblast, and it was related with the excessive mitochondrial fragmentation of osteoblasts. Inhibition of MCU could largely restore the mitochondrial dynamic balance. And the effect of MCU on the mitochondrial fission was closely related to ER-Mito Contact. We have rich experience for the mitochondrial dynamic related reserch, based on our previous studies, in this project, we will investigate the role of MCU mediated mitochondrial dynamic on the osseointegration of titanium implants in diabetic mouse model and the underlying mechanisms. Using the MCU knockout transgenic mice, by establishing the diabetic implant model and high glucose treated osteoblast model, we will assess in-depth the role of MCU in regulating the mitochondrial dynamics, and how it contributes to the implant osseointegration in diabetic mice. ER-Mito Contact represents an important platform for the regulation of mitochondrial division. Our data showed an evidence which supports a role for ER-Mito Contact in the MCU regulated mitochondrial fission process, thus, we hypothesized that MCU controls mitochondrial dynamics via the regulation of ER-Mito Contact, MCU-FUNDC1-Drp1 and calcium homeostasis related signaling pathway maybe the underlying mechanism. MCU regulation of ER-Mito Contact and the underlying pathway will also be discussed in this project. The results of this project may provide new insights in the research field of mitochondrial dynamics, and may have both theoretical and clinical significance as they will provide molecular biology evidence for novel prevention and therapeutic strategies of MCU and related signaling pathway as the targets to improve diabetic dental implant osseointegration.

糖尿病是牙种植体骨结合不良的高风险因素，线粒体动力学失衡（过度分裂）是糖尿病相关骨损伤的重要特征。线粒体钙单向转运体（MCU）对线粒体动力学具有关键调控作用，然而作用机制尚不清楚，且相关研究尚未涉及骨生物学领域。申请者发现高糖状态下成骨细胞MCU表达上调，促使线粒体过度分裂，此过程与内质网—线粒体接触（ER-Mito Contact）机制密切相关。据此，基于申请者前期围绕线粒体动力学研究较为扎实的工作基础，本课题采用MCU基因敲除小鼠，构建糖尿病种植模型及体外成骨细胞高糖损伤模型，全面探究MCU调控线粒体动力学在糖尿病种植体骨结合中的作用及机制，并对“ER-Mito Contact为MCU调控线粒体动力学过程的重要功能位点”的假设进行论证，探讨潜在分子信号通路。研究成果有望为线粒体动力学相关研究启发新的思路，并为建立以MCU及相关信号分子为靶点改善糖尿病种植体骨结合的干预措施提供理论依据。

糖尿病是牙种植体骨结合不良的高风险因素，线粒体动力学与细胞生理病理反应息息相关，在骨代谢相关的成骨、破骨分化调控中发挥重要作用。线粒体钙单向转运体（Mitochondrial calcium uniporter, MCU）对线粒体动力学具有关键调控作用，而相关研究在骨生物学领域仍相对匮乏。本课题采用MCU转基因小鼠，结合体内体外研究，探究MCU对骨组织结构及成骨细胞分化功能的影响作用及机制。本课题按照原定计划实施，课题进展顺利，研究发现：（1）MCU基因敲除及MCU过表达小鼠骨形成不良、骨小梁微结构不佳；（2）MCU功能抑制及MCU功能激动使骨髓间充质干细胞及小鼠胚胎成骨细胞前体细胞（MC3T3-E1）成骨相关基因表达水平降低、成骨分化功能明显减弱；（3）体外抑制或激动MCU可促进MC3T3-E1细胞线粒体过度分裂、促使线粒体膜电位降低、ROS积累增多等线粒体功能损伤；（4）体内给予抗氧化药物可逆转MCU基因过表达小鼠骨形成不良；（5）线粒体动力学靶向的种植体表面改性可增强糖尿病鼠种植体骨结合。综合以上一系列的体内和体外实验结果，本课题新发现了MCU通过促进线粒体过度分裂、增加线粒体ROS积累、降低线粒体膜电位、引起线粒体功能障碍，最终导致成骨细胞成骨功能损伤，并且MCU-Drp1可能作为治疗糖尿病状态下骨愈合不良、种植体骨结合不佳的潜在靶点。 . 课题共标注发表全文学术论文24 篇，其中 SCI 论文 16篇，包含 5分以上6篇，10分以上2篇。共培养4名博士生毕业，3名硕士毕业。在此基础上，课题负责人获得四川大学科技进步二等奖、华夏医学科技奖三等奖、中华口腔医学会科技奖三等奖等荣誉。