Elucidating the novel mechanism of importins in NLRP6 inflammasome regulation

摘要 炎性小体是多蛋白质信号传导支架，其在受到细胞因子刺激时在胞质溶胶中形成。 病原体和损伤信号激活caspase-1。典型的炎性小体传感器是 主要是核苷酸结合结构域（NBD）和富含亮氨酸的重复序列（NLR）蛋白，如 如NLRP 1、NLRP 3和NLRP 6。一旦炎性小体被激活，半胱天冬酶-1就会被募集到细胞中。 平台，并通过邻近诱导的自蛋白水解激活。活化的caspase-1过程 pro-IL-1b、pro-IL-18和成孔蛋白gasdermin D（GSDMD），导致 在这些细胞因子的成熟和释放，以及细胞死亡中起作用。NLRP 6播放 在宿主防御中的多功能角色。它在肠道和肝脏中高度表达。的 据报道，NLRP 6的炎性体功能可保护宿主免受病原体逃避 和损伤引起的组织损伤。另一方面，过量的NLRP 6炎性体 激活和随后的过度活跃的IL-18信号传导可能加剧组织损伤 并引起慢性炎性疾病如炎性肠病（IBD）。是否 存在一种内在的细胞信号来调节NLRP 6炎性体的活性，从而成为一种 有趣的问题这个问题对于理解我们的身体如何维持组织至关重要 通过利用这种重要的炎性小体来维持体内平衡，并为以下疾病提供靶向治疗： 某些疾病。 核输入是天然免疫防御的一个重要细胞过程 激活转录因子进入细胞核以产生干扰素。植物本身 已经报道了通过病原体效应介导的核 易位在我们的初步研究中，我们发现一种常见的核输入蛋白-b1， 受体，抑制dsRNA诱导的NLRP 6的液-液相分离， 暗示核输入和NLRP 6炎性体信号传导之间的潜在联系。 在本申请中，我们将研究重要蛋白在调节NLRP 6中的潜在作用。 通过解决两个问题来研究炎性小体：1）重要蛋白-NLRP 6相互作用的分子基础 （冷冻电子显微镜和生物化学），和2）重要-B1的作用，负 在病毒感染时调节NLRP 6炎性体（炎性体细胞生物学）。

Abstract Inflammasomes are multi-protein signaling scaffolds that form in the cytosol upon stimulation by pathogen and damage signals to activate caspase-1. Canonical inflammasome sensors are mainly nucleotide-binding domain (NBD) and leucine-rich repeat containing (NLR) proteins, such as NLRP1, NLRP3 and NLRP6. Once inflammasome is activated, caspase-1 is recruited to the platform and activated through proximity-induced autoproteolysis. Activated caspase-1 processes pro-interleukin (IL)-1b, pro-IL-18, and the pore-forming protein gasdermin D (GSDMD), resulting in the maturation and release of these cytokines, as well as pyroptotic cell death. NLRP6 plays versatile roles in host defense. It is highly expressed in the intestine and the liver. The inflammasome function of NLRP6 has been reported to protect the host from pathogen evasion and injury-induced tissue damage. On the other hand, the excessive NLRP6 inflammasome activation and the subsequent hyperactive IL-18 signaling may exacerbate the tissue damage and cause chronic inflammatory diseases such as inflammatory bowel disease (IBD). Whether there is an intrinsic cellular signal that tunes the activity of NLRP6 inflammasome becomes an intriguing question. The question is critical to understanding how our body maintains tissue homeostasis by harnessing this important inflammasome and to provide targeted therapy for certain diseases. Nuclear import is an essential cellular process in innate immune defense by translocating activated transcription factors into the nucleus for interferon production. Plant NLRs themselves have been reported to enable host defense through pathogen effector-mediated nuclear translocation. In our preliminary study, we found that importin-b1, a common nuclear import receptor, inhibits dsRNA-induced liquid-liquid phase separation of NLRP6 in-vitro, which implicates the potential link between nuclear import and NLRP6 inflammasome signaling. In this application, we will investigate the potential role of importins in regulating the NLRP6 inflammasome by tackling two questions: 1) molecular basis of the importin-NLRP6 interaction (cryo-electron microscopy and biochemistry), and 2) the roles of importin-b1 in negatively regulating NLRP6 inflammasome upon viral infection (inflammasome cell biology).