Defining the non-apoptotic role of Caspase-8 activity in anti-bacterial immune defense

定义 Caspase-8 活性在抗菌免疫防御中的非凋亡作用

基本信息

批准号：
9229681
负责人：
IGOR E BRODSKY
金额：
$ 40.74万
依托单位：
UNIVERSITY OF PENNSYLVANIA
依托单位国家：
美国
项目类别：
财政年份：
2017
资助国家：
美国
起止时间：
2017-03-01 至 2022-02-28
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/9229681
关键词：
Address Alpha Cell Anti-Bacterial Agents Antibiotic Resistance Apoptosis Apoptotic Aspartate Bacterial Infections Biological Assay CASP8 gene Caspase Cell Death Cell Survival Cells Cleaved cell Communicable Diseases Cytokine Gene Defect Detection Development Dimerization Disease Notification Ectopic Expression Enzymes Exhibits Failure Gene Expression Generations Genes Genetic Transcription Goals Gram-Negative Bacterial Infections HDAC7 histone deacetylase Heterodimerization Histone Deacetylase Homo Homodimerization Host Defense Human Immune Immune signaling Immunity Individual Infection Infection Control Inflammation Inflammation Mediators Inflammatory Knock-in Mouse Knowledge Laboratories Mediating Methods Molecular Morbidity - disease rate Mus Mutant Strains Mice Outcome Pathogenicity Pathologic Pattern recognition receptor Play Production Publishing Receptor Signaling Recruitment Activity Regulation Resistance to infection Role Sepsis Septic Shock Signal Pathway Signal Transduction Testing Therapeutic Toll-like receptors Transcription Repressor/Corepressor United States Up-Regulation Yersinia Yersinia infections adaptive immunity antimicrobial bacterial genetics cytokine defined contribution dimer foodborne foodborne illness immunopathology immunoregulation in vivo insight knock-down macrophage monomer mortality mouse model mutant new therapeutic target novel novel strategies pathogen prevent promoter public health relevance response tool transcription factor

项目摘要

Project Summary Bacterial infection is sensed by evolutionarily conserved pattern recognition receptors, including Toll Like Receptors (TLRs). TLR signaling induces production of inflammatory mediators that play a key role in controlling infection as well as in the pathologic sequellae of infection, including gram-negative sepsis. Recent studies in our laboratory and others revealed a role for the cysteine protease, caspase-8 (Casp8) as an important regulator of the transcriptional response to bacterial infection. Casp8-deficient mice and humans are highly susceptible to mucosal bacterial infection, implicating Casp8 as a key regulator of anti-bacterial immune defense. Intriguingly, our preliminary studies demonstrate that Casp8 plays a cell-intrinsic role in regulating transcription of key anti-microbial inflammatory mediators in response to gram-negative bacterial infection and TLR stimulation, and this is entirely independent of the well-established role of Casp8 in regulating cell death. Autoprocessing of Casp8 at a key aspartate residue leads to stabilization of the enzymatically active Casp8 homodimer, and subsequent cleavage of its apoptotic substrates. Conversely, Casp8 functions as a heterodimer with cFLIP to limit cell death and promote cell survival. We have now generated a novel Casp8DA mutant mouse in which the ability of Casp8 to homodimerize is eliminated, and have found that Casp8DA macrophages have a significant defect in their ability to induce inflammatory cytokine production in response to TLR engagement. These studies provoke the conceptually novel hypothesis that the Casp8 homodimer plays a non-apoptotic role in the induction of antimicrobial responses during bacterial infection or TLR engagement. We propose two Specific Aims to address this important gap in our knowledge. First we will utilize newly- generated mutant mice that distinguish between the function of the caspase-8 homo- and hetero-dimers to define the define molecular mechanism of caspase-8-mediated control of inflammatory cytokine gene expression. In particular we will test whether caspase-8 regulates inflammatory gene expression by cleaving and inactivating transcriptional repressors or activating a transcriptional inducer. Second, we will use well- defined murine models of systemic bacterial infection to interrogate the in vivo role of caspase-8-dependent inflammatory cytokine production in innate and adaptive antimicrobial immune defense.

项目概要细菌感染是由进化上保守的模式识别受体感知的，包括 Toll Like 受体 (TLR)。 TLR 信号传导诱导炎症介质的产生，在炎症反应中发挥关键作用控制感染以及感染的病理后遗症，包括革兰氏阴性败血症。最近的我们实验室和其他实验室的研究揭示了半胱氨酸蛋白酶 caspase-8 (Casp8) 作为对细菌感染的转录反应的重要调节因子。 Casp8 缺陷小鼠和人类极易受到粘膜细菌感染，表明 Casp8 是抗菌免疫的关键调节因子防御。有趣的是，我们的初步研究表明 Casp8 在调节细胞内发挥着细胞内在的作用响应革兰氏阴性细菌感染的关键抗微生物炎症介质的转录和 TLR 刺激，这完全独立于 Casp8 在调节细胞死亡中的既定作用。 Casp8 在关键天冬氨酸残基处的自动处理导致酶活性 Casp8 的稳定同二聚体，以及随后其凋亡底物的裂解。相反，Casp8 的功能是异二聚体与 cFLIP 一起限制细胞死亡并促进细胞存活。我们现在已经生成了一个新颖的 Casp8DA Casp8同源二聚化能力被消除的突变小鼠，并发现Casp8DA 巨噬细胞在诱导炎症细胞因子产生的能力上存在显着缺陷 TLR 参与。这些研究提出了概念上新颖的假设，即 Casp8 同二聚体发挥着在细菌感染或 TLR 参与过程中诱导抗菌反应中的非凋亡作用。我们提出了两个具体目标来解决我们知识中的这一重要差距。首先我们将利用新的- 产生了能够区分 caspase-8 同源二聚体和异源二聚体功能的突变小鼠定义 caspase-8 介导的炎症细胞因子基因控制的分子机制表达。我们将特别测试 caspase-8 是否通过裂解来调节炎症基因表达以及使转录阻遏物失活或激活转录诱导物。其次，我们要好好利用—— 定义了全身细菌感染的小鼠模型，以探究 caspase-8 依赖性的体内作用先天性和适应性抗菌免疫防御中炎症细胞因子的产生。