RNF125调控NLRP3炎症小体的分子机制研究

Inflammasomes are key signaling platforms that detect pathogenic microorganisms and sterile stressors, and that activate the highly pro-inflammatory cytokines interleukin-1β(IL-1β) and interleukin-18 (IL-18). Stringent control of inflammasome signaling pathway is important for keeping immunological balance, yet the regulatory mechanisms responsible for its tight regulation are still poorly understood. Here we found RNF125, an E3 ligase that inhibit type I interferon (IFN) signaling pathway by targeting RIG-1 for degradation, was required for the optimal activation of IL-1β production. Specially, NLRP3 is speculated as a candidate substrate of E3 ligase RNF125 since the mutation of RNF125 ubiquitin ligase activity lose its ability to active NLRP3 inflammasome. Taken together, we would like to further explore the interaction of RNF125 with NLRP3 and their biological significance. We believe our investigation of RNF125 on NLRP3 inflammasome pathway will not only help us to further understand the mechanisms responsible for crosstalk between inflammasome and type I IFN innate immune pathway but will also provide novel therapeutic target for preventing or treating patients with inflammatory and/or infectious diseases.

炎症小体是宿主固有免疫的重要组成部分，其适度激活对清除病原微生物等损伤起到重要作用，但是过度激活会导致多种组织、器官的伤害，因此炎症小体复合物的活性需要精确调控。前期工作中，我们通过酵母双杂交筛选到一个负调控I型干扰素的E3连接酶RNF125可能与NLRP3发生相互作用，并通过免疫共沉淀证明了二者的相互作用。初步研究还发现RNF125促进NLRP3 K63连接的泛素化，增加NLRP3稳定性，促进NLRP3炎症小体IL-1β分泌的功能；而RNF125泛素化酶活性缺失则丧失了以上功能。综上，RNF125很有可能以NLRP3为其E3连接酶底物参与调控炎症小体的激活。接下来我们拟利用体内、体外细胞及动物模型，确立RNF125与NLRP3的相互作用及其生理学意义，揭示RNF125调控炎症小体信号通路的分子机制，探索固有免疫不同信号通路间交互作用的机理，并有可能为抗炎及抗感染药物开发提供潜在的靶点。

炎症小体是宿主固有免疫的重要组成部分，其适度激活对清除病原微生物等损伤起到重要作用，但是过度激活会导致多种组织、器官的伤害，因此炎症小体复合物的活性需要精确调控。前期工作中，我们筛选到一个负调控I型干扰素的E3连接酶RNF125促进炎症小体IL-1β分泌的功能，而E3连接酶缺失的RNF125则丧失了这种功能。接下来的研究我们通过免疫共沉淀发现RNF125可与NLRP3、caspase-1的亚基p20发生相互作用。我们的研究还发现RNF125促进NLRP3、p20 K63连接的泛素化，增加NLRP3、p20稳定性，进而促进炎症小体IL-1β分泌的功能；而RNF125泛素化酶活性缺失则丧失了以上功能。我们利用体内、体外细胞实验及RNF125敲除的动物模型（如肾炎模型、肠炎模型），进一步确立了RNF125正调控炎症小体的功能及RNF125调控炎症小体生理学意义。本研究揭示了RNF125调控炎症小体信号通路的分子机制，探索固有免疫不同信号通路间交互作用的机理，并为抗炎及抗感染药物开发提供潜在的靶点。