Bacterial effectors targeting the IKK/NF-kB pathway

针对 IKK/NF-kB 通路的细菌效应子

基本信息

批准号：
8495491
负责人：
Philip Ross Hardwidge
金额：
$ 8.81万
依托单位：
KANSAS STATE UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2013
资助国家：
美国
起止时间：
2013-01-11 至 2017-12-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8495491
关键词：
Animal Model Bacteria Bacterial Infections Biochemical Cells Chimeric Proteins Citrobacter Citrobacter rodentium Complex Data Diarrhea Disease Disease Outbreaks Escherichia coli Escherichia coli EHEC Food Genetic Transcription Goals Health Host Defense Human Immune Response Genes Immune response Immune system Immunity Infection Inflammatory Inflammatory Response Lipopolysaccharides Meat Molecular Mus Mutation NF-kappa B Names Natural Immunity Nuclear Nuclear Import Nuclear Translocation Pathway interactions Phosphorylation Phosphotransferases Play Process Protein Kinase Proteins Qualifying Research Ribosomal Proteins Role Salmonella Series Serotyping Shigella Signal Transduction Signal Transduction Pathway Substrate Specificity System Testing Type III Secretion System Pathway Vegetables Virulence Virulent Water Water Pollution Wild Type Mouse Work Yersinia enteric pathogen foodborne outbreak improved inhibitor/antagonist innovation novel pathogen prevent promoter public health relevance research study response ribosomal protein S3 spatiotemporal success transcription factor

项目摘要

DESCRIPTION (provided by applicant): Despite costly attempts to reduce bacterial contamination of water, meat, and vegetables, Shiga toxin- producing E. coli (STEC) and related enteric pathogens (e.g. Salmonella, Shigella, Yersinia) are causing increasingly frequent outbreaks of food-borne diarrheal disease, thus constituting enormous health burdens. These pathogens use a type III secretion system (T3SS) to inject virulence proteins (effectors) into host cells. While T3SS effectors clearly play essential roles in bacterial virulence, the mechanisms by which they subvert the functions of host cells to promote pathogen survival are incompletely characterized. We are studying the mammalian signal transduction pathways targeted by STEC effectors, with the ultimate goal of improving our ability to prevent and to treat bacterial infections. We have made the important and unique discovery that the STEC strains associated with severe diarrheal disease outbreaks in humans express a pair of homologous effectors that differentially regulate host innate immunity by disrupting the transcriptional responses to infection that are normally coordinated by the NF-kB pathway. NF-kB activity at key innate immune response genes is regulated by ribosomal protein S3 (RPS3), which possesses an accessory nuclear function as an NF-kB subunit. We discovered that the NleH1 effector protein inhibits RPS3 nuclear translocation, reducing NF-kB activity at specific promoters. Specifically, NleH1 inhibits the Ik¿ kinase complex (IKK¿) from phosphorylating RPS3, a critical requirement for its nuclear translocation. STEC strains also encode a homologous effector named NleH2. Despite sharing 84 % identity with NleH1, NleH2 stimulates rather than inhibits RPS3/NF-kB-dependent transcription. We hypothesize that the NleH1 and NleH2 effectors promote bacterial virulence by subverting the pro- inflammatory responses to infection normally regulated by RPS3/NF-kB and propose the following specific aims: 1) Quantify the importance of NleH effectors to bacterial virulence using animal models of diarrheal disease. 2) Characterize the molecular mechanism by which NleH1 inhibits IKK¿ phosphorylation of RPS3 to prevent its nuclear import. 3) Elucidate mechanistic differences between NleH1 and NleH2 and their pathophysiological significance in regulating RPS3/NF-kB-dependent signaling. Successful completion of the proposed research will 1) reveal how these bacterial effectors selectively modulate innate immunity; 2) clarify how pathogens have evolved to co-opt the accessory nuclear functions of ribosomal proteins; and 3) characterize how bacteria have integrated their virulence proteins into host signal transduction pathways in specific spatiotemporal contexts.

描述（由申请人提供）：尽管为减少水、肉类和蔬菜的细菌污染付出了高昂的代价，但产志贺毒素的大肠杆菌 (STEC) 和相关肠道病原体（例如沙门氏菌、志贺氏菌、耶尔森氏菌）正在导致越来越频繁的爆发食源性腹泻病，从而构成巨大的健康负担。这些病原体使用 III 型分泌系统（T3SS）注入毒力蛋白。虽然 T3SS 效应子显然在细菌毒力中发挥着重要作用，但它们破坏宿主细胞功能以促进病原体存活的机制尚未完全表征，我们正在研究 STEC 效应子所针对的哺乳动物信号转导途径。最终目标是提高我们的预防和治疗能力我们做出了重要而独特的发现，即与人类严重腹泻病爆发相关的 STEC 菌株表达一对同源效应子，通过破坏通常由 NF-协调的感染转录反应来差异调节宿主先天免疫。 kB 通路。关键先天免疫反应基因的 NF-kB 活性由核糖体蛋白 S3 (RPS3) 调节，该蛋白具有 NF-kB 亚基的辅助核功能。 NleH1 效应蛋白抑制 RPS3 核易位，降低特定启动子处的 NF-kB 活性。具体来说，NleH1 抑制 Ik¿。磷酸化 RPS3 的激酶复合物 (IKK¿) 是其核转位的关键要求，它还编码名为 NleH2 的同源效应子，尽管 NleH2 与 NleH1 具有 84% 的同一性，但 NleH2 会刺激而不是抑制 RPS3/NF-kB 依赖性转录。我们发现，NleH1 和 NleH2 效应子通过破坏通常由感染调节的促炎反应来促进细菌毒力。 RPS3/NF-kB 并提出以下具体目标：1) 使用腹泻病动物模型量化 NleH 效应子对细菌毒力的重要性 2) 表征 NleH1 抑制 IKK 的分子机制。 3) 阐明 NleH1 和 NleH2 之间的机制差异及其在调节 RPS3/NF-kB 依赖性信号传导中的病理生理学意义。成功完成拟议研究将 1) 揭示这些细菌效应子如何选择性调节先天性。免疫；2）阐明病原体如何进化以选择核糖体蛋白的辅助核功能；3）描述细菌如何整合其功能；在特定时空背景下将毒力蛋白引入宿主信号转导途径。