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（由申请人提供）：尽管为减少水、肉和蔬菜中的细菌污染进行了昂贵的尝试，但产生志贺毒素的大肠杆菌（STEC）和相关的肠道病原体（如沙门氏菌、志贺氏菌、耶尔森氏菌）正在引起越来越频繁的食源性腹泻病爆发，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）将毒力蛋白（效应器）注入宿主细胞。虽然T3SS效应物显然在细菌毒力中起着重要作用，但它们破坏宿主细胞功能以促进病原体存活的机制尚不完全清楚。我们正在研究STEC效应物靶向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