Host pathogen signaling in the intestine

肠道中的宿主病原体信号传导

• 批准号: 8358606
• 负责人: VANESSA SPERANDIO
• 金额: $ 21.21万
• 依托单位: UT SOUTHWESTERN MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-06-22 至 2014-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8358606
• 关键词: Adrenergic Receptor; Animals; Aspartate; Attenuated; Bacteria; Chemicals; Citrobacter rodentium; Enterobacteriaceae; Epinephrine; Escherichia coli EHEC; Escherichia coli O157; G-Protein-Coupled Receptors; Gastrointestinal tract structure; Genes; Genetic Transcription; Grant; Histidine; Homologous Gene; Hormones; Human; Immune; In Vitro; Infant; Infection; Intestines; Mammals; Metabolic; Modeling; Mus; Norepinephrine; OmpR protein; Organism; Oryctolagus cuniculus; Pathogenesis; Phosphorylation; Physiology; Plants; Reporting; Research Personnel; Signal Transduction; Site; Stress; System; Virulence; biological adaptation to stress; gastrointestinal; in vivo; inorganic phosphate; mutant; pathogen; response; sensor histidine kinase; trait; transcription factor

DESCRIPTION (provided by applicant): The deadly gastrointestinal pathogen enterohemorrhagic E. coli (EHEC) O157:H7 exploits sensing the host's stress hormones epinephrine (epi) and norepinephrine (NE) to activate its virulence traits. Stress responses have a profound effect in an organism's physiology and survival, and are also sensed by bacteria as a means to gauge the metabolic and immune state of the host. These hormones in mammals are sensed by adrenergic receptors that are G-coupled protein receptors (GPCRs). Bacteria, however, sense these hormones through histidine sensor kinases (HKs), which act in concert with a response regulator (RR) protein constituting a two-component system. Upon sensing its signal, the HK autophosphorylates in a histidine residue, and then transfers this phosphate to an aspartate residue in its cognate RR. The majority of the RRs are transcription factors, which are activated upon phosphorylation. We have first reported EHEC's two adrenergic receptors: the HKs QseC and QseE with QseE being downstream of QseC in this signaling cascade (given that transcription of qseE is activated through QseC). QseC homologues are present in at least 25 important human and plant pathogens, while the distribution of QseE is limited to enteric bacteria. EHEC qseC and qseE mutants have been shown to be attenuated for virulence in vitro and in vivo using an infant rabbit model of infection However, the study of the true interplay between EHEC and the host through this signaling system has been challenging due to the lack of murine models to study EHEC pathogenesis in the GI tract. Hence, many investigators utilize the natural mouse pathogen Citrobacter rodentium as a surrogate model for EHEC GI pathogenesis in mice. All of the known virulence genes of EHEC have been validated in vivo using C. rodentium murine infections. The utilization of the C. rodentium model capitalizes in merging the powerful genetically tractability of host and pathogen to unravel the mechanisms involved in host recognition and infection. We have shown that epi and NE activate expression of all virulence genes in C. rodentium, in a similar scenario to what we have observed with EHEC (Preliminary results). C. rodentium qseC and qseE mutants are also attenuated for virulence in vitro and in vivo (murine infection) (Preliminary studies), making this a genetically tractable model to dissect the contribution of host chemical signals during pathogenesis. In accordance, the Specific Aim of this application is: Characterize the contribution of the host Epi/NE hormones to C. rodentium pathogenesis during murine infection. PUBLIC HEALTH RELEVANCE: Several human deadly pathogens tightly regulate expression of their virulence traits; when these pathogens infect a suitable host, many chemical signals are sensed so they can gage the host and site of infection, and subsequently activate expression of their virulence genes. Some of these signals are the host stress hormones epinephrine and norepinephrine to activate their virulence genes. In this grant we will study how Citrobacter rodentium (a mouse pathogen used as a model for E. coli O157:H7) sense and respond to these hormones in vitro and during animal infection.

描述（由申请人提供）：致命的胃肠道病原体肠出血性大肠杆菌。大肠杆菌（EHEC）O 157：H7利用感应宿主的应激激素肾上腺素（epi）和去甲肾上腺素（NE）来激活其毒力特征。 应激反应对生物体的生理和生存有着深远的影响，细菌也能感受到应激反应，以此来衡量宿主的代谢和免疫状态。哺乳动物中的这些激素由肾上腺素能受体感知，肾上腺素能受体是G偶联蛋白受体（GPCR）。然而，细菌通过组氨酸传感器激酶（HK）来感知这些激素，所述组氨酸传感器激酶与构成双组分系统的反应调节剂（RR）蛋白协同作用。在感受到它的信号后，HK在组氨酸残基中自磷酸化，然后将该磷酸转移到其同源RR中的天冬氨酸残基。大多数RR是转录因子，其在磷酸化后被激活。我们首次报道了EHEC的两种肾上腺素能受体：HK的QseC和QseE，其中QseE在该信号级联中位于QseC的下游（假定qseE的转录通过QseC激活）。QseC同源物存在于至少25种重要的人类和植物病原体中，而QseE的分布仅限于肠道细菌。EHEC qseC和qseE突变体在体外和体内使用幼兔感染模型显示毒力减弱。然而，由于缺乏研究胃肠道中EHEC发病机制的鼠模型，因此研究EHEC与宿主之间通过该信号系统的真正相互作用具有挑战性。因此，许多研究者利用天然小鼠病原体啮齿柠檬酸杆菌作为小鼠肠出血性大肠杆菌胃肠道发病机制的替代模型。所有已知的肠出血性大肠杆菌毒力基因均已在体内用C.鼠类感染利用C.啮齿动物模型将宿主和病原体强大的遗传可塑性融合在一起，以揭示宿主识别和感染的机制。我们已经证明，epi和NE激活了C.啮齿类，在类似的情况下，我们已经观察到与肠出血性大肠杆菌（初步结果）。C.啮齿类qseC和qseE突变体在体外和体内（鼠感染）的毒力也减弱（初步研究），使其成为一种遗传上易于处理的模型，以剖析发病过程中宿主化学信号的贡献。因此，本申请的具体目的是：表征宿主Epi/NE激素对C.啮齿动物感染过程中的发病机制。 公共卫生相关性：几种人类致命病原体严格调节其毒力性状的表达;当这些病原体感染合适的宿主时，许多化学信号被感知，因此它们可以测量宿主和感染部位，随后激活其毒力基因的表达。其中一些信号是宿主应激激素肾上腺素和去甲肾上腺素激活其毒力基因。在本研究中，我们将研究啮齿类柠檬酸杆菌（一种小鼠病原体，用作大肠杆菌的模型）是如何在大肠杆菌中生长的。coliO 157：H7）在体外和动物感染过程中对这些激素感测和应答。