Role of Protein Ubiquitination in Sepsis

项目摘要 败血症及其并发症是当代医学面临的一大挑战。大约25万例 败血症每年在美国导致死亡，给医疗保健系统带来了巨大的成本。取决于 根据医疗标准，全球败血症患者的死亡率从30%到70%不等， 总死亡率约为50%。NLRP3是大分子信号复合体的关键组成部分，称为 炎症体促进依赖caspase1的IL-1β促炎细胞因子的产生 在脓毒症的发展过程中。尽管导致NLRP3炎症体激活的因素已经被 经过广泛研究，负性调节NLRP3炎症体激活的机制，以及 因此，对脓毒症的控制，尚不清楚。我们发现NLRP3被泛素化抑制，Cbl-b是一种E3 泛素连接酶。这一发现的意义在于观察到，内毒素 与注射或盲肠结扎穿孔(CLP)相比，注射(LP)或盲肠结扎穿孔(CLP)可显著降低Cblb-/-小鼠的死亡率 野生型(WT)对照，这种由内毒素诱导的Cblb-/-小鼠死亡率增加可被IL-1阻断 受体拮抗剂或通过引入NLRP3缺乏症。因此，我们的中心假设是，在脓毒症期间， CBL-b被自动激活/激活，泛素化NLRP3，进而抑制NLRP3并减弱 NLRP3介导的先天反应。我们建议确定1)Cbl-b如何调节NLRP3炎症体 激活；2)Cb1-b是否以及如何利用CLP诱导体内控制非典型性NLRP3炎症体 以脓毒症和内毒素感染性休克为研究模型。了解Cbl-b在调节细胞周期中的作用 NLRP3炎症小体介导的信号通路将为临床治疗提供新的思路和策略 与败血症作斗争。

Project Summary Sepsis with its complications is a major challenge in contemporary medicine. Approximately 250,000 cases of sepsis lead to fatalities in the USA annually at huge costs for the healthcare system. Depending on the standards of medical care, the worldwide mortality rates in septic humans range from 30% to 70% with an aggregate mortality rate of ~50%. NLRP3 is a key component of the macromolecular signaling complex called the inflammasome that promotes caspase 1-dependent production of IL-1β pro-inflammatory cytokine involved in the development of sepsis. Although the factors leading to NLRP3 inflammasome activation have been extensively studied, the mechanisms for negatively regulating the activation of the NLRP3 inflammasome, and thus, controlling sepsis, are not known. We found that NLRP3 is inhibited by ubiquitination by Cbl-b, an E3 ubiquitin ligase. The significance of this finding is demonstrated by the observation that that lipopolysaccharide (LPS) injection or cecal ligation and puncture (CLP) induces a significant mortality in Cblb-/- mice compared to wild-type (WT) controls, and this increased mortality in Cblb-/- mice induced by LPS is blocked by an IL-1 receptor antagonist or by introducing NLRP3 deficiency. Therefore, our central hypothesis is that during sepsis, Cbl-b is autoubiquitinated/activated and ubiquitinates NLRP3, which in turn inhibits NLRP3 and attenuates NLRP3-mediated innate responses. We propose to determine 1) how Cbl-b regulates NLRP3 inflammasome activation; 2) whether and how Cbl-b controls non-canonical NLRP3 inflammasome in vivo using CLP-induced sepsis and LPS-induced septic shock as the study models. Understanding the role of Cbl-b in regulating the NLRP3 inflammasome-mediated signaling pathway will provide novel insights and therapeutic strategies to combat sepsis.