Tryptophan derivatives in EHEC pathogenesis

EHEC 发病机制中的色氨酸衍生物

• 批准号: 9386057
• 负责人: VANESSA SPERANDIO
• 金额: $ 45.85万
• 依托单位: UT SOUTHWESTERN MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-12-01 至 2019-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9386057
• 关键词: Affect; Bacteria; Bacterial Adhesins; Binding; Biochemical; Cells; Chemicals; Colon; Communication; DNA; Digestion; Disease; Disease Outbreaks; Enteral; Enterochromaffin Cells; Enterocytes; Environment; Enzymes; Epithelial Cells; Escherichia coli EHEC; Excision; Food; Functional Gastrointestinal Disorders; Gastrointestinal Diseases; Gastrointestinal tract structure; Gene Expression; Gene Expression Regulation; Genetic; Health; Hemorrhagic colitis; Human; In Vitro; Indoles; Infection; Intestinal Diseases; Intestinal Mucosa; Intestines; Lamina Propria; Lesion; Mediating; Membrane; Microbe; Mucous body substance; Mus; Neurons; Neurotransmitters; Pathogenesis; Pathogenicity Island; Peristalsis; Phosphorylation; Physiology; Play; Production; Regulation; Reporting; Role; Serotonin; Signal Transduction; Signaling Molecule; Site; System; Translating; Tryptophan; Tryptophan 5-monooxygenase; Vasodilation; Virulence; Virus; Vitamins; commensal bacteria; gastrointestinal; gut microbiota; in vivo; inorganic phosphate; member; microbiota; monoamine; pathogen; public health relevance; receptor; response; reuptake; sensor; sensor histidine kinase; small molecule; trait; transcription factor

DESCRIPTION (provided by applicant): The human gastrointestinal (GI) tract is inhabited by trillions of commensal bacteria that play crucial roles in human physiology. Chemical communication between microbes and their hosts underlies the basis of their associations The GI pathogen enterohemorrhagic E. coli (EHEC), responsible for outbreaks of bloody diarrhea worldwide, exploits cell-to-cell signaling between the gastrointestinal microbial flora and the hos as a means to gage and recognize the host environment. This signaling is predicated upon signaling molecules that are tryptophan derivatives in the colon such as the host neurotransmitter serotonin and the microbiota produced indole. Serotonin is a neurotransmitter that is primarily synthesized in the GI tract Serotonin is released into the lamina propria to activate peristalsis, secretion, and vasodilation. However, it has been recently reported that serotonin is also secreted into the lumen, but its function in this compartment remains unclear. Many functional GI disorders are associated with alterations in serotonin signaling, but the effect of serotonin signaling on bacterial-mediated GI disorders remains unknown. Although a number of bacteria and viruses have been show to influence serotonin signaling, no study has investigated the effect that serotonin has on bacterial pathogenesis. The bacterially produced tryptophan derivative indole is known to influence intestinal barrier function, and has also been shown to regulate virulence gene expression in EHEC. We identified the bacterial membrane bound histidine sensor kinase (HK) CpxA as a sensor of serotonin and indole. CpxA is the HK that upon autophosphorylation, phosphotranfers to the response regulator (RR) CpxR, which is a transcriptional factor. CpxA also dephosphorylates this RR, and the phosphorylation state of CpxR defines which sites it binds to on its DNA targets. Through CpxA, both serotonin and indole decrease expression of the locus of enterocyte effacement (LEE) in EHEC, which encodes a type three secretion system (T3SS), effectors and an adhesin necessary for EHEC to form lesions on enterocytes leading to intestinal disease. Both serotonin and indole inhibit CpxA's autophosphorylation, consequently decreasing the expression of its targets. Altogether, these results suggest that CpxA is an important small molecule receptor crucial for cell-to-cell signaling and inhibition of virulence of GI pathogens. Accordingly, the specific aims of this application are: 1) In vitro mechanistic studies on virulence gene regulation by tryptophan derivatives. 2) Serotonin and indole signaling at the microbiota, pathogen and host cell interface. 3) Serotonin regulation of bacterial virulence in the murine GI tract.

描述（由申请人提供）：人类胃肠道（GI）中居住着数万亿在人体生理学中发挥关键作用的肠道细菌。微生物与宿主之间的化学通讯是它们之间联系的基础。大肠杆菌（EHEC）是引起全球出血性腹泻的原因，它利用胃肠道微生物植物群和宿主之间的细胞间信号传导作为衡量和识别宿主环境的手段。这种信号传导是基于结肠中色氨酸衍生物的信号分子，如宿主神经递质血清素和微生物群产生的吲哚。5-羟色胺是一种主要在胃肠道合成的神经递质。5-羟色胺被释放到固有层中以激活血管扩张、分泌和血管舒张。然而，最近有报道称，血清素也分泌到管腔中，但其在该隔室中的功能仍不清楚。许多功能性胃肠道疾病与5-羟色胺信号的改变有关， 血清素信号对细菌介导的胃肠道疾病的影响仍然未知。虽然一些细菌和病毒已被证明会影响血清素信号，但没有研究调查血清素对细菌发病机制的影响。已知细菌产生的色氨酸衍生物吲哚影响肠屏障功能，并且还显示调节EHEC中的毒力基因表达。我们确定了细菌膜结合组氨酸传感器激酶（HK）CpxA作为5-羟色胺和吲哚的传感器。CpxA是在自身磷酸化后磷酸转移到应答调节因子（RR）CpxR的HK，CpxR是一种转录因子。CpxA也使这种RR去磷酸化，CpxR的磷酸化状态决定了它与其DNA靶点上的哪些位点结合。通过CpxA，5-羟色胺和吲哚都降低了EHEC中肠细胞消失（LEE）位点的表达，该位点编码EHEC在肠细胞上形成损伤导致肠道疾病所需的第三型分泌系统（T3 SS）、效应器和粘附素。5-羟色胺和吲哚都抑制CpxA的自磷酸化，从而降低其靶点的表达。总之，这些结果表明，CpxA是一种重要的小分子受体，对细胞间信号传导和抑制GI病原体的毒力至关重要。因此，本申请的具体目的是：1）色氨酸衍生物对毒力基因调控的体外机制研究。2)微生物群、病原体和宿主细胞界面的血清素和吲哚信号传导。3)血清素对小鼠胃肠道细菌毒力的调节。