Bacterial effectors targeting the IKK/NF-kB pathway

针对 IKK/NF-kB 通路的细菌效应子

• 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
• 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

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（由适用提供）：尽管试图减少细菌污染水，肉和蔬菜的污染，但志贺毒素生产大肠杆菌（STEC）和相关的促进病原体（例如沙门氏菌，志贺氏菌，耶尔森氏菌，耶尔森氏菌）越来越经常导致食品 - 苯乙烯疾病疾病的爆发，从而促成了康复性疾病，从而造成了健康的健康。这些病原体使用III型分泌系统（T3SS）将病毒蛋白（效应子）注入宿主细胞。虽然T3SS效应器显然在细菌病毒中起着重要作用，但它们颠覆宿主细胞促进病原体存活的功能的机制是未完全表征的。我们正在研究由STEC生效者靶向的哺乳动物信号转导途径，以提高我们预防和治疗的能力 细菌感染。我们已经做出了一个重要而独特的发现，即人类中与严重的腹泻病暴发相关的STEC菌株表达了一对同源效应，通过破坏通常由NF-KB途径协调的感染的转录反应来不同地调节宿主先天免疫学。核糖体蛋白S3（RPS3）调节了关键先天免疫增强基因的NF-KB活性，该核糖体蛋白S3（RPS3）具有辅助核功能作为NF-KB亚基。我们发现NLEH1效应蛋白抑制RPS3核转运，从而降低了特定启动子的NF-KB活性。具体而言，NLEH1从磷酸化RPS3中抑制IK？激酶复合物（IKK？），这是其核易位的关键要求。 STEC菌株还编码一个名为NLEH2的同源效应子。尽管与NLEH1共享84％的身份，但NLEH2刺激而不是抑制RPS3/NF-KB依赖性转录。我们假设NLEH1和NLEH2效应子通过颠覆正常受RPS3/NF-KB调节的感染的促炎反应来促进细菌病毒，并提出以下特定目的：1）量化NLEH对细菌效应的重要性，使用诊断性疾病动物模型对细菌病毒的重要性。 2）表征了NLEH1抑制IKK？kk的RPS3磷酸化以防止其核进口的分子机制。 3）阐明NLEH1和NLEH2之间的机械差异及其在确定RPS3/NF-KB依赖性信号传导时的病理生理意义。拟议研究的成功完成1）揭示这些细菌如何有选择地调节先天免疫； 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）表征细菌如何在特定的空间时间环境中将其病毒蛋白整合到宿主信号转移途径中。