ZBP1 activation

项目摘要/摘要 推测的核苷酸传感器ZBP1可以触发坏死性细胞死亡或转录反应， 基因研究表明，这一途径是宿主抵御一系列病毒病原体所必需的。 此外，最近的研究表明，在某些情况下，ZBP1可以在无菌条件下激活 条件，暗示内源性细胞产物作为潜在的ZBP1配体。然而，尽管进行了长时间的研究， 负责激活ZBP1及其与核苷酸感应的其他成分相互作用的配体 机制仍然存在争议，双链RNA、核糖核蛋白和病毒Z-型核酸 所有物种都被认为是配基。ZBP1只与另一个共享其关键的核苷酸感应域 哺乳动物蛋白质，ADAR1。ADAR1灭活内源性dsRNA以限制自身炎症 病理，人类患者ADAR1基因突变导致严重的自身免疫性疾病--阿卡迪氏 古铁雷斯综合征(AGS)。我们假设ADAR1和ZBP1竞争一个共同的内源性 配体，需要ADAR1使其失活才能限制ZBP1的激活。为了支持这一观点，病理学 在一种新开发的人类ADAR1突变小鼠模型中观察到，通过消融 ZBP1。这一发现支持了我们的假设，也暗示了自身免疫病理与丢失有关 ADAR1功能的下降是由ZBP1依赖的炎症和细胞死亡激活引起的。使用这些 作为观察的起点，这里提出的工作将通过以下方式研究ZBP1的激活和功能 追求三个目标：第一，我们将利用ADAR1突变和额外的新小鼠模型来促进 内源性ZBP1配体的分离与鉴定。第二，我们将评估以下方面的贡献 坏死性上睑下垂及ZBP1介导的炎症信号对人动物模型病理的影响 ADAR1突变触发的AGS，并测试坏死下垂抑制剂改善这一病理变化的能力。 第三，我们将研究其他dsRNA传感器，包括MDA5和PKR在ZBP1配体形成中的作用 和坏死性下垂途径的激活。总之，这项工作将揭示ZBP1功能的关键方面，以及 确定ZBP1依赖型坏死性下垂为改善AGS的潜在治疗靶点。

Project Summary/Abstract The putative nucleotide sensor ZBP1 can trigger necroptotic cell death or transcriptional responses, and genetic studies indicate that this pathway is required for host defense against an array of viral pathogens. Furthermore, recent studies show that in some circumstances ZBP1 can become activated under sterile conditions, implicating endogenous cellular products as potential ZBP1 ligands. However, despite long study, the ligand responsible for activating ZBP1 and its interplay with other components of the nucleotide sensing machinery remain controversial, with double-stranded RNA, ribonucleoprotein, and viral Z-form nucleic acid species all suggested as ligand. ZBP1 shares its key nucleotide sensing domain with only one other mammalian protein, ADAR1. ADAR1 inactivates endogenous dsRNA species to limit autoinflammatory pathology, and mutations in ADAR1 in human patients lead to the severe autoimmune disease Acardi- Goutieres syndrome (AGS). We hypothesize that ADAR1 and ZBP1 compete for a common endogenous ligand, whose inactivation by ADAR1 is required to limit ZBP1 activation. In support of this idea, the pathology observed in a newly-developed mouse model of human ADAR1 mutation was fully rescued by ablation of ZBP1. This finding supports our hypothesis, and also implies that autoimmune pathology associated with loss of ADAR1 function is caused by activation of ZBP1-dependent inflammation and cell death. Using these observations as a starting point, the work proposed here will investigate ZBP1 activation and function by pursuing three Aims: First, we will use ADAR1 mutation and additional new mouse models to facilitate isolation and identification of an endogenous ZBP1 ligand. Second, we will assess the contribution of necroptosis as well as ZBP1-mediated inflammatory signaling to the pathology of an animal model of human AGS triggered by ADAR1 mutation, and test the ability of necroptosis inhibitors to ameliorate this pathology. Third, we will investigate the role of other dsRNA sensors, including MDA5 and PKR, to ZBP1 ligand formation and necroptotic pathway activation. Together this work will both reveal key aspects of ZBP1 function, and identify ZBP1-dependent necroptosis as a potentially treatable target to ameliorate AGS.