FGFs/FGFR3抑制TRAF6/NF-κB通路及其在骨性关节炎发病中作用和机制研究

Osteoarthritis (OA) is a frequently-occurred disease in the elderly, which mainly affects the weight-bearing joints, causing dysfunction. Up to date, there is no effective drug and treatments in OA clinic. It is gradally recognized that osteoarthritis is an inflammatory disease. Inflammatory factors from different source and the hyperactivation of NF-κB signaling pathway play vital roles in abnormally increased degradation of extracellular matrix and premature differentiation of chondrocytes, two important pathogenic factors in OA. FGFR3 and its cognate ligand FGF18 can relieve the articular cartilage degeneration of OA mice, but the underlying mechanism is still largely unknown. Recently, we found that FGFR3 can downregulate the TRAF6 or IL-1β activated NF-κB signaling pathway in different cells. More interestingly, we found that FGFR3 can interact TRAF6 directly through the TRAF interacting motif in its kinase domain. FGFR3 also inibit the dimerization of TRAF6 and the K63-linked ubiquitination of TRAF6. However, the role of the inhibition of FGFR3 to TRAF6-mediated NF-κB signaling pathway in macrophage and articular chondrocytes in the pathogenesis of OA and its underlying mechanism is still unclear. To reveal the mechamisms of the inhibition of FGFs/FGFR3 to NF-κB pathway,the detailed molecular events of FGFR3-TRAF6 interaction will be studied by co-immunoprecipitations, GST-pull down and immunofluorescence staining. Furthermore, we will employ the inducible FGFR3 chondrocyte-specific and macrophagy-specific FGFR3 conditional knockout mice combining with OA mice model and the specific inhibitor of NF-κB pathway to identify the role NF-κB signaling pathway in the process of regulating the articular cartilage homeostasis by FGFR3/FGF18. The research is focus on the mechanisms of the interaction between FGFR3 and TRAF6 and and its role in the regulating the homeostasis of articular cartilage, to supply the experimental basis of the OA research and drug development.

骨性关节炎（OA）是常见多发病，多累及负重关节，导致功能障碍，由于缺乏有效防治措施，严重危害国民健康。OA是炎症因子介导的复杂疾病，多种来源的炎症因子及其激活的NF-κB通路在关节软骨细胞外基质代谢异常与软骨细胞异常肥大分化中发挥关键作用。骨发育关键调控基因FGF18/FGFR3明显延缓OA进程，但机制不清。前期我们发现FGFR3负调控NF-κB通路，FGFR3与TRAF6存在直接相互作用并抑制TRAF6泛素化。但FGFR3是否通过调控炎症反应延缓OA进程目前不清楚。为进一步明确相关作用及机制，我们将利用巨噬细胞特异敲除和软骨细胞可诱导敲除FGFR3小鼠，通过小鼠OA模型结合NF-κB抑制剂及体外细胞模型，深入研究FGFR3对NF-κB通路的调控及其在OA发病中的作用与机制。本研究将揭示FGFR3对炎症反应的调控及其在OA发病中的意义，为理解OA的机制、研发OA防治措施提供理论和实验依据。

骨性关节炎（OA）是常见多发病，多累及负重关节，导致功能障碍，由于缺乏有效防治措施，严重危害国民健康。OA是炎症因子介导的复杂疾病，多种来源的炎症因子及其激活的NF-κB通路在关节软骨细胞外基质代谢异常与软骨细胞异常肥大分化中发挥关键作用。骨发育关键调控基因FGF18/FGFR3明显延缓OA进程，但机制不清。本研究中，我们围绕科学假设FGFs/FGFR3可降低TRAF6/NF-κB信号通路并在OA发生发展中发挥重要作用开展相关研究。我们分别在巨噬细胞与关节软骨细胞中特异敲除FGFR3，通过对OA相关表型的分析，观察了在软骨细胞以及巨噬细胞中FGFs/FGFR3信号在OA表型的变化和机制。在进一步的机制研究中，通过结合细胞生物学与分子生物学相关技术，我们发现骨关节发育调控的关键基因FGFR3可通过胞内的TRAF相互作用结构域与TRAF6蛋白直接相互作用，与FGFR3的相互作用抑制TRAF6的二聚化及泛素化，抑制多种炎症因子激活的NF-κB信号通路和下游基因的表达；此外，我们还发现，FGFR3通过抑制滑膜巨噬细胞以及关节软骨细胞中的NF-κB信号通路，通过调控巨噬细胞的活化以及软骨细胞的存活等途径，在OA的发生、发展中发挥了重要作用。我们的研究在整体动物水平研究了骨发育关键的调控信号FGFs/FGFR3与炎症调控关键通路TRAF6/NF-KB之间的交互作用，并揭示了其在OA发生发展中的重要作用和相关机制，为进一步深入研究FGFs/FGFR3在OA中的作用和经FGFs/FGFRs调控OA提供了坚实的实验基础。部分研究结果发表在（Annals of the Rheumatic Diseases，2020年）后，国家自然基金委的网站给予了介绍。