Caspase-1 Activation by the Inflammasomes

炎性小体是一种多蛋白复合体，它们聚集在一起激活caspase-1以响应组织损伤。 以及被微生物或病毒病原体感染。一旦被激活，caspase-1就会处理非活性的 IL-1β(IL-1β)和IL-18(IL-18)产生活性促炎细胞因子IL-1β和IL-18 分别为18。此外，caspase-1处理Gasdermin蛋白GSDMD来诱导下垂或 炎性细胞死亡。NLRP3炎症体在不同的炎症体中是独特的，因为它是 由不同的病原体相关和危险相关分子模式(PAMP和DAMPS)激活 来自微生物病原体的感染，或组织损伤。因此，不受控制的NLRP3激活 可导致许多人类炎症性疾病，包括痛风、关节炎、动脉粥样硬化和2型 糖尿病。这些看似无关的刺激激活NLRP3的机制人们知之甚少，但目前 目前认为需要两个不同的信号：启动信号或由Toll样受体产生的信号1 (TLR)和导致跨高尔基体网络(TGN)碎裂的激活信号或信号2，以及 与NEK7结合。申请人实验室的研究表明，信号1诱导翻译后 通过MyD88和TRIF信号通路在关键位点修饰NLRP3 NLRP3的寡聚。在这一应用中，建议进行研究以阐明TLR如何诱导PTM 通过使用质谱学来促进NLRP3炎症体的翻译后启动 识别和表征NLRP3的磷酸化和其他PTM谱中的所有关键变化 信号1，并研究这些变化如何有助于NLRP3的激活。其他目标将 研究信号1和信号1诱导的PTM对NLRP3与分散的TGN和 NEK7，并确定了TGN相关的激酶最终组装和激活所需的 炎症者。最后，初步证据表明，激酶参与了细胞内离子的调节。 动态平衡通过信号2对NLRP3的激活进行负向控制。因此，额外的实验将 研究巨噬细胞中这些激酶的信号如何影响NEK7的磷酸化和相互作用 NLRP3，以及这些激酶的遗传缺陷如何影响NLRP3介导的促炎反应 体内的PAMP和DAMPS。这项研究的结果将提供对这些途径的基本新见解 调节NLRP3炎症体的组装和激活，以及控制 它的激活。这项研究的成功完成应该会对实地产生很大的影响，因为它提供了一个统一的 NLRP3如何被一组异常不同的激活刺激调节的范例。理解 这些机制具有重大的科学和卫生意义，因为这将有助于我们更好地理解 NLRP3相关疾病的分子基础及其在长期治疗中的作用 来缓解这些炎症性疾病。

Inflammasomes are multi-protein complexes that assemble to activate caspase-1 in response to tissue damage and infection by microbial or viral pathogens. Once activated, caspase-1 processes the inactive proforms of interleukin-1β (IL-1β) and interleukin-18 (IL-18) to produce the active pro-inflammatory cytokines IL-1β and IL- 18, respectively. In addition, caspase-1 processes the gasdermin protein GSDMD to induce pyroptosis or inflammatory cell death. The NLRP3 inflammasome is unique among the different inflammasomes in that it is activated by diverse pathogen-associated and danger-associated molecular patterns (PAMPs and DAMPs) derived from infection with microbial pathogens, or tissue damage. As a result, uncontrolled NLRP3 activation can lead to a number of human inflammatory diseases, including gout, arthritis, atherosclerosis, and type 2 diabetes. The mechanism of NLRP3 activation by these seemingly unrelated stimuli is poorly understood but is currently believed to require two distinct signals; a priming signal or “signal 1” produced by Toll-like receptors (TLRs) and an activation signal or “signal 2” that induces fragmentation of trans Golgi network (TGN) and binding to NEK7. Studies in the applicant's laboratory demonstrated that signal 1 induces post-translational modification (PTM) of NLRP3 at critical sites via the MyD88 and TRIF signaling pathways and partial oligomerization of NLRP3. In this application, studies are proposed to elucidate how TLR-induced PTM contributes to posttranslational priming of the NLRP3 inflammasome by employing mass spectrometry to identify and characterize all critical changes in the phosphorylation and other PTM profile of NLRP3 induced by signal 1, and investigating how these changes contribute to activation of NLRP3. Additional aims will investigate the effect of signal 1 and signal 1-induced PTM on NLRP3 association with dispersed TGN and NEK7, and identify the TGN-associated kinases required for final assembly and activation of the inflammasome. Finally, preliminary evidence suggest that kinases involved in the regulation of intracellular ion homeostasis exert negative control on activation of NLRP3 by signal 2. Thus, additional experiments will investigate how signaling from these kinases in macrophages impacts NEK7 phosphorylation and interaction with NLRP3, and how genetic deficiency in these kinases impacts NLRP3-mediated pro-inflammatory responses to PAMPs and DAMPs in vivo. Results from this research will provide fundamental new insights into the pathways that regulate the assembly and activation of the NLRP3 inflammasome, and the cellular mechanisms that control its activation. Successful completion of this study should have a high impact on the field by providing a unifying paradigm for how NLRP3 can be regulated by an exceptionally diverse group of activating stimuli. Understanding these mechanisms is of great scientific and health significance as this should better our understanding of the molecular basis of NLRP3-related diseases and should in the long term help in the development of therapeutics to alleviate these inflammatory diseases.