Understanding the pathway that links lipopolysaccharide (LPS) to mitochondrial function using a novel mouse model

 性状（由申请方提供）：微生物产物的先天免疫识别在防止细菌和病毒感染方面起着关键作用。现在认识达特线粒体以各种方式参与对先天免疫识别的应答。线粒体已被描述为先天免疫信号传导的枢纽，充当信号传导复合物组装的支架。此外，越来越多的证据表明，主要由线粒体介导的细胞代谢和能量学在先天免疫细胞的激活和功能中起着关键作用。该实验室已经确定了一种线粒体蛋白，ECSIT（Toll途径中进化保守的信号中间体），它似乎具有生物能量和免疫功能。在这项提案中，目的是开发一种遗传模型，以更好地了解ECSIT如何将TLR激活与免疫细胞中的下游线粒体功能联系起来。ECSIT最初被鉴定为Toll/IL-1受体下游NF-κB信号通路的组分。它已被证明，ECSIT是所需的线粒体氧化磷酸化系统（OXPHOS）的复合物I的组装，以及有效的呼吸。此外，该实验室最近的一篇论文表明，ECSIT还控制了TLR 1、2和4参与后线粒体活性氧（mROS）的产生，并且这种mROS对于有效杀死吞噬细菌至关重要。迄今为止，这些发现 似乎是第一个描述TLR和线粒体之间的直接通讯。为了进一步研究ECSIT在介导TLR信号传导至线粒体中的作用，产生了传统的ECSIT KO小鼠;然而，ECSIT缺失导致胚胎死亡。为了克服在研究ECSIT的生理功能中随之而来的困难，已经产生了条件靶向ECSIT敲除（CKO）小鼠。在这个提议中，目的是开发和表征ECSIT CKO小鼠，然后利用这个模型来确定LPS信号如何通过ECSIT调节线粒体功能。具体而言，提出了实验来表征稳态条件下和响应于LPS暴露的ECSIT CKO小鼠（R21），以及利用ECSIT CKO模型来定义ECSIT在将LPS/TLR信号传导与下游线粒体功能联系起来中的作用（R33）。

 DESCRIPTION (provided by applicant): Innate immune recognition of microbial products plays a critical role in protection from infection by bacteria and viruses. It is now appreciated tat mitochondria participate in the response to innate immune recognition in various ways. Mitochondria have been described as hubs for innate immune signaling, acting as scaffolds for signaling complex assembly. Moreover, accumulating evidence suggests that cellular metabolism and energetics, which are largely mediated by mitochondria, play a critical role in activation and function of innate immune cells. This laboratory has identified a mitochondrial protein, ECSIT (Evolutionarily Conserved Signaling Intermediate in Toll pathways), which appears to have both bioenergetic and immune functions. In this proposal, the aim is to develop a genetic model to attain a better understanding of how ECSIT links TLR activation with downstream mitochondrial functions in immune cells. ECSIT was originally identified as a component of the NF-κB signaling pathway downstream of the Toll/IL-1 receptors. It has since been shown that ECSIT is required for assembly of complex I of the mitochondrial oxidative phosphorylation system (OXPHOS), as well as for efficient respiration. In addition, a recent paper from this laboratory demonstrated that ECSIT also controls the production of mitochondrial reactive oxygen species (mROS) following engagement of TLRs 1, 2 and 4, and that this mROS is essential for efficient killing of phagocytosed bacteria. To date, these findings appear to be the first to describe direct communication between TLRs and mitochondria. To further study the role of ECSIT in mediating TLR signaling to the mitochondria, a traditional ECSIT KO mouse was generated; however, ECSIT deletion resulted in embryonic lethality. To overcome the consequent difficulty in studying the physiological function of ECSIT, conditionally-targeted ECSIT knock-out (CKO) mice have been generated. In this proposal, the intent is to develop and characterize the ECSIT CKO mouse, and then utilize this model to determine how LPS signaling through ECSIT regulates mitochondrial function. Specifically, experiments are proposed to characterize the ECSIT CKO mice under steady-state conditions and in response to LPS exposure (R21), as well as to utilize the ECSIT CKO model to define the role of ECSIT in linking LPS/TLR signaling to downstream mitochondrial function(s) (R33).