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

• 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
• 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

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.

项目摘要 通过进化保守的模式识别受体感受细菌感染，包括TOLL 受体（TLR）。 TLR信号传导引起炎症介质的产生，在 控制感染以及感染的病理性后遗症，包括革兰氏阴性败血症。最近的 在我们的实验室和其他研究中的研究揭示了半胱氨酸蛋白酶的作用，caspase-8（casp8）作为一种 对细菌感染的转录反应的重要调节剂。 CASP8缺乏小鼠和人类是 高度容易受到粘膜细菌感染的影响，这意味着CASP8是抗细菌免疫的关键调节剂 防御。有趣的是，我们的初步研究表明，CASP8在调节中起着细胞中的作用 响应革兰氏阴性细菌感染和 TLR刺激，这完全独立于CASP8在调节细胞死亡中的良好作用。 在关键天冬氨酸残留物处的CASP8自动加入会导致酶活性CASP8的稳定 同二聚体，并随后切割其凋亡底物。相反，CASP8充当 与CFLIP的异二聚体限制细胞死亡并促进细胞存活。我们现在已经产生了一个新颖的casp8da 消除了CASP8均匀二聚体能力的突变小鼠，并发现CASP8DA 巨噬细胞在其诱导炎症细胞因子产生的能力上有明显的缺陷 TLR参与。这些研究引发了概念上新的假设，即Casp8同二聚体发挥 在细菌感染或TLR参与过程中诱导抗菌反应的非凋亡作用。 我们提出了两个具体的目标，以解决我们知识的这一重要差距。首先，我们将使用新的 生成的突变小鼠，区分caspase-8均二聚体的功能 定义caspase-8介导的炎症细胞因子基因的控制的分子机制 表达。特别是我们将测试caspase-8是否通过分裂来调节炎症基因表达 并灭活转录阻遏物或激活转录诱导剂。其次，我们将使用良好 定义的全身细菌感染的鼠模型，以询问caspase-8依赖性的体内作用 先天和适应性抗菌免疫防御中的炎症细胞因子产生。