Perturbation of core processes triggers host defense against pathogens

核心过程的扰动触发宿主对病原体的防御

• 批准号: 9312823
• 负责人: Emily R Troemel
• 金额: $ 30.61万
• 依托单位: UNIVERSITY OF CALIFORNIA, SAN DIEGO
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-08-01 至 2019-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9312823
• 关键词: Acute; Address; Affect; Animals; Anti-Bacterial Agents; Attenuated; Binding; CCAAT-Enhancer-Binding Protein-alpha; CCAAT-Enhancer-Binding Proteins; CCAAT-enhancer-binding protein-gamma; Caenorhabditis elegans; Cell Line; Cell physiology; Cells; Cessation of life; Communicable Diseases; Data; Disease; Epithelial; Epithelial Cells; Exotoxins; Family; Genes; Genetic Screening; Genetic Transcription; Genetic Translation; Goals; Heterodimerization; Host Defense; Host Defense Mechanism; Human; Immune; Immune response; Immunity; In Vitro; Infection; Inflammation; Inflammatory; Innate Immune Response; Integration Host Factors; Intestines; Lead; Learning; Mammals; Mediating; Microbe; Molecular Structure; Monitor; Mus; Nematoda; Nuclear; Open Reading Frames; Orthologous Gene; Outcome; Pathogen detection; Pathogenicity; Phenotype; Play; Process; Proteins; Pseudomonas aeruginosa; Research; Resistance to infection; Role; System; Testing; Tissues; Toxin; Translational Repression; Translations; Up-Regulation; Virulence; Work; attenuation; cell type; combat; cytokine; foodborne; improved; in vivo; infectious disease treatment; innovation; insight; macrophage; microbial; novel strategies; novel therapeutics; pathogen; protein expression; public health relevance; response; sensor; tool; transcription factor; waterborne

 DESCRIPTION (provided by applicant): Intestinal epithelial cells must detect and respond to microbial pathogens that cause foodborne and waterborne diseases, yet also discriminate them from the trillions of other microbes in the intestine that are innocuous or even beneficial. The mechanisms by which host cells make this distinction are poorly understood. Our long-term goal is to better understand how pathogens are discriminated from other microbes by intestinal cells, as well as by other cell types. Closing this gap in our understanding may allow for improved treatment of infectious diseases, as well as better control of inflammatory disorders. Our central hypothesis is that a major strategy for discriminating pathogens from other microbes is through sensing perturbations of core host processes that are commonly targeted by pathogen-derived toxins. The objective here is to identify the mechanism by which the nematode C. elegans detects such pathogen-induced perturbations. C. elegans provides an excellent system to address this question because it relies on epithelial defense and is extremely tractable. We will also extend our findings to mammals, to investigate a similar protective host response. Our recent findings have shown that perturbation of core processes like mRNA translation triggers activation of the C. elegans bZIP transcription factor ZIP-2 to provide host defense (Dunbar et al, 2012). ZIP-2 upregulates a suite of genes involved in intracellular defense, and promotes resistance to infection (Estes et al, 2010). Our unpublished results suggest that ZIP-2 works together with CEBP-2, which is the C. elegans ortholog of mammalian C/EBP-, a transcription factor that mediates acute response to infection in mammals. We hypothesize that 1) ZIP-2 and CEBP-2 form a heterodimeric transcription factor that promotes host defense, 2) ZIP-2 translation is upregulated upon infection by an upstream open reading frame (uORF) that acts as a sensor for translational attenuation, and 3) mammals deploy a similar host defense system. We will test our first hypothesis in Specific Aim 1, where we will examine CEBP-2 and ZIP-2 phenotypes, expression and interaction. We will test our second hypothesis in Specific Aim 2, where we investigate the underlying mechanisms of the surprising result that translational attenuation increases ZIP-2 protein levels. We will analyze the zip-2 uORF (Dunbar et al, 2012), and characterize hits from a genetic screen for regulators of ZIP- 2. In Aim 3, we will build off our preliminary findings into mammals, testing a role for C/EBP- in the protective response to toxins, and investigating the functional significance of this response in vivo. This approach is innovative, because it analyzes how cells detect perturbations in core processes targeted by pathogens, which is a newly appreciated mode of animal host defense. It also investigates the role and function of uORFs, which are found in 30-50% of all mouse and human genes, but poorly understood. The proposed research is significant because it will provide insight into how cells respond specifically to pathogenic attack, and may lead to new treatments for infections in the intestine as well as other tissues, to better combat infectious disease.

 描述（由申请人提供）：肠上皮细胞必须检测并响应引起食源性和水源性疾病的微生物病原体，同时将它们与肠道中数万亿种无害甚至有益的其他微生物区分开来。人们对宿主细胞进行这种区分的机制知之甚少。我们的长期目标是更好地了解肠道细胞以及其他细胞类型如何将病原体与其他微生物区分开来。弥合我们理解上的这一差距可能有助于改善传染病的治疗，以及更好地控制炎症性疾病。我们的中心假设是，区分病原体和其他微生物的主要策略是通过感知核心宿主过程的扰动，这些过程通常是病原体衍生毒素的目标。这里的目的是确定线虫检测此类病原体引起的扰动的机制。线虫提供了一个很好的系统来解决这个问题，因为它依赖于上皮防御并且非常容易处理。我们还将把我们的发现扩展到哺乳动物，以研究类似的保护性宿主反应。 我们最近的研究结果表明，mRNA 翻译等核心过程的扰动会触发线虫 bZIP 转录因子 ZIP-2 的激活，以提供宿主防御（Dunbar 等人，2012）。 ZIP-2 上调一系列参与细胞内防御的基因，并促进对感染的抵抗力（Estes 等，2010）。我们未发表的结果表明，ZIP-2 与 CEBP-2 一起发挥作用，CEBP-2 是哺乳动物 C/EBP- 的线虫直系同源物，C/EBP- 是一种介导哺乳动物对感染的急性反应的转录因子。 我们假设 1) ZIP-2 和 CEBP-2 形成异二聚体转录因子，促进宿主防御，2) ZIP-2 翻译在上游开放阅读框 (uORF) 感染时上调，上游开放阅读框 (uORF) 充当翻译减弱的传感器，3) 哺乳动物部署类似的宿主防御系统。我们将在具体目标 1 中测试我们的第一个假设，其中我们将检查 CEBP-2 和 ZIP-2 表型、表达和相互作用。我们将在特定目标 2 中测试我们的第二个假设，其中我们研究翻译衰减增加 ZIP-2 蛋白水平这一令人惊讶的结果的潜在机制。我们将分析 zip-2 uORF（Dunbar 等人，2012），并表征 ZIP-2 调节剂基因筛选的命中。在目标 3 中，我们将在哺乳动物中建立我们的初步发现，测试 C/EBP- 在毒素保护性反应中的作用，并研究这种反应在体内的功能意义。这种方法是创新的，因为它分析了细胞如何检测病原体针对的核心过程中的扰动，这是一种新近被认可的动物宿主防御模式。它还研究了 uORF 的作用和功能，这些 uORF 存在于 30-50% 的小鼠和人类基因中，但人们对其知之甚少。这项拟议的研究意义重大，因为它将深入了解细胞如何对病原体攻击做出特异性反应，并可能带来针对肠道和其他组织感染的新疗法，以更好地对抗传染病。