Runx1对骨发育与骨病理模型中成骨、软骨细胞分化机制的研究

Runt-related transcription factor 1 (Runx1) plays an important role in angiogenesis, malignant hematopoiesis and thymus development by controlling a large number of genes which are in charge for hematopoiesis. However, the role and molecular mechanism of Runx1 on development and pathology of osteoblasts and chondrocytes, which are originated from the same embryonic mesenchymal stem cells (EMSCs), are mostly not well known. In this applied project, we firstly construct the Runx1 conditional knock out (CKO) model in mice by using Cre-Floxp system, and we aim to explore the impact of Runx1 CKO on the development of bone and cartilage from the different stages in the process of EMSC differentiation into bone and cartilage. Then we construct an OA model by using anterior cruciate ligament transection(ACLT) based on the specific Runx1ff/Osx-Cre, Runx1ff/Col2-Cre and Runx1ff/Col10-Cre, and aim to explore the role of Runx1 in the damages of cartilage and pathological changes of subchondral bone. We further collect the changed information about DNA microarray and proteomics based on difference between the wide type group and Runx1 CKO group, screen the most correlative proteins and explore the related protein-protein (protein-DNA) interaction throughco-immunoprecipitation (Co-IP) or chromatin immunoprecitation(ChIP). Finally, based on the specific role of Runx1 in hematopoiesis, we aim to find out the distribution changes of vascular and lymphatic system in the development and pathology of bone and subchondral bone, which could set up a potential relationship between the circulatory system and skeletal system. To understand the specific mechanism about the role of Runx1 in the development and pathology of bone and cartilage could help us to know the potential of Runx1 in skeletal system and provide the novel theoretical support on the cure about OA disease.

转录因子Runx1因对循环系统造血基因的调控，在血管生成、恶性造血和胸腺发育中发挥了重要作用。近来Runx1对间充质干细胞骨向分化的功能使人们认识到其在骨骼系统中的重要性。然而对于其如何具体调控间充质干细胞分化为成熟成骨和软骨的发育过程以及骨性关节炎OA的发病过程尚不清楚。本课题拟以Cre-Floxp系统为基础，利用骨发育不同时期的Cre工具鼠，构建Runx1条件性敲除小鼠模型，研究在发育的不同阶段，Runx1对成骨、软骨的作用；并且以Runx1条件性敲除小鼠为基础，构建前交叉韧带切断手术的OA病理模型，研究Runx1在OA病理过程中对软骨和软骨下骨成骨的作用；接着运用细胞分子生物学找到并验证Runx1在成骨和软骨的发育和OA病理过程的分子作用机制；最后，以Runx1为纽带，通过研究骨发育和骨病理过程中脉管系统的变化揭示循环系统和骨骼系统潜在联系。通过本课题以期为OA治疗提供新的靶点。

转录因子Runx1因在血液系统中的重要调控作用而广为人知，但Runx1对骨骼系统的影响却并不清楚。本课题首先基于Cre-Floxp系统，构建了在软骨系和成骨系中条件性敲除的小鼠来研究Runx1在骨骼系统发育和骨性关节炎进程中的作用；同时基于腺相关病毒载体系统，构建了骨性关节炎模型下Runx1超表达基因治疗体系。结果发现：1、Runx1可促进软骨到成骨的细胞谱系分化，同时通过增强软骨和成骨生成的方式促进骨发育；2、Runx1在骨性关节炎中敲低后，会加速关节炎进程，导致关节软骨层破坏加重和生长板软骨骨化加剧；3、在骨性关节炎中使用AAV-Runx1超表达体系缓解了关节软骨层的破坏和生长板软骨的骨化速度，进而保护了关节组织；4、我们同时发现了Runx1缓解关节炎的新型重要调控因子：跨膜转化蛋白-1 (Transmembrane anterior posterior transformation 1, TAPT1), 蛋白RIC1同源物 (Protein RIC1 homolog, RIC1)和成纤维细胞生长因子-20 (Fibroblast growth factor 20, FGF20)。综上，通过系统的研究，我们全面阐释了Runx1在骨骼系统发育和骨性关节炎进程中的重要作用，同时也找到了在骨性关节炎治疗中的新型潜在靶点。