Biochemical mechanisms underlying inflammasome function

先天免疫系统作为动植物的第一道防线，通过及早发现迫在眉睫的威胁以及由此引发的促炎反应来协调细胞损伤和感染。这些免疫机制是由一个古老的模式识别受体(PRRs)家族介导的。在大PRR家族中，NLRP亚家族蛋白已成为细胞内危险信号的关键感受器。现在迅速发展的生物学模型表明，各种NLRP在启动对细胞损伤的炎症反应中起着至关重要的作用；然而，关于该蛋白家族及其信号复合体的基本生物化学的关键方面仍未解决。NLRP3是研究最深入的，被认为是典型的炎症体形成成员。NLRP家族成员包含一个具有ATP结合和水解性的中心Nacht结构域(有时被称为核苷酸结合寡聚域或NOD)，被认为调节NLRP寡聚和炎症体激活。*整个NLRP家族(14个成员)的基本生物化学仍未完全确定。许多关于NLRPs的酶活性和炎性小体形成的内在调节的假设主要基于类比，缺乏确凿的证据。进一步表征炎症体激活的酶学特征以及最近发现的翻译后修饰在调节炎症信号通路中的整合，将对全面理解该蛋白家族至关重要。在这方面，我们认为不同NLRP-Nacht结构域的特定生化特性决定了不同的催化活性，这反过来可以影响齐聚和炎症信号。因此，对NLRP蛋白的酶学和ATP在驱动炎症体相关信号通路中的作用的全面定义将对理解先天免疫过程至关重要。很明显，对整个NLRP家族的整体研究是必要的，我们将创造性地促进对NLRP家族作为一个整体及其组装成功能性炎症体的倾向的理解。为了解决知识不足的问题，需要建立有效生产所有NLRP蛋白的系统，完成酶功能的生化评估，开发新的生物询问技术和试剂，并需要对催化Nacht结构域进行准确的结构定义。我们在重组NLRP蛋白生产方面的技术进步支持对蛋白质和炎症体催化功能的生化分析以及结构生物学方法。

The innate immune system acts as the first line of defense for animals and plants in reconciling cellular injury and infection through the early detection of impending threats, and consequential triggering of pro-inflammatory responses. These immune mechanisms are mediated by an ancient family of pattern recognition receptors (PRRs). Within the greater PRR family, the NOD-like receptors-containing pyrin (NLRP) subfamily of proteins have emerged as key sensors of intracellular danger signals. Rapidly developing biological models now indicate the various NLRPs are of paramount importance in initiating inflammatory responses to cellular injury; however, critical aspects regarding the underlying biochemistry of this protein family and their signaling complexes remain unresolved. NLRP3 is the most thoroughly studied and is considered to be the prototypical inflammasome-forming member. NLRP family members contain a central NACHT domain with ATP-binding and hydrolysis properties, (sometimes referred to as the nucleotide-binding oligomerization domain or NOD), that are thought to regulate NLRP oligomerization and inflammasome activation. *** The basic biochemistry of the entire NLRP family (14 members) remains incompletely characterized. Many assumptions regarding the enzymatic activity of NLRPs and the intrinsic regulation of inflammasome formation are based primarily upon analogy with limited corroborating evidence. Further characterization of the enzymology of inflammasome activation as well as the integration of recently revealed post-translational modifications in regulating inflammatory signaling pathways will be critical for a comprehensive understanding of this protein family. In this regard, we propose that specific biochemical properties of different NLRP-NACHT domains drive distinctions in catalytic activities, which in turn can impact upon oligomerization and inflammatory signaling. Thus, a comprehensive definition of the enzymology of NLRP proteins and the role of ATP in driving inflammasome-associated signaling pathways will be critical for understanding of the innate immune process. It is clear that holistic studies of the entire NLRP family are necessary, and we will creatively advance understanding of the NLRP family as a whole and their propensity to assemble into functional inflammasomes. To address the knowledge deficit, systems for the effective production of all NLRP proteins are required, biochemical assessments of enzymatic function need to be completed, novel technologies and reagents for biological interrogations should be developed, and precise structural definitions of the catalytic NACHT domain are necessary. Our technical advances in recombinant NLRP protein production support biochemical analyses of protein and inflammasome catalytic function as well as structural biology approaches.