The impact of ER stress on Salmonella Typhimurium infections

内质网应激对鼠伤寒沙门氏菌感染的影响

• 批准号: 10708073
• 负责人: Arina Marijke Keestra-Gounder
• 金额: $ 38.1万
• 依托单位: UNIVERSITY OF COLORADO DENVER
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-09-20 至 2027-07-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10708073
• 关键词: ATF6 gene; Actins; Apoptosis; Apoptotic; Autophagocytosis; Bacterial Infections; Binding; Biological Process; Calcium; Calcium Signaling; Cell Death Induction; Cell physiology; Cells; Colitis; Complex; Cytoskeleton; Data; Development; Endoplasmic Reticulum; Epithelial Cells; Functional disorder; Future; Gastroenteritis; Gastrointestinal tract structure; Gene Expression; Gene Targeting; Genes; Gram-Negative Bacteria; Homeostasis; Human; Immune response; Immune signaling; Immunologic Receptors; In Vitro; Induction of Apoptosis; Infection; Inflammation; Inflammatory; Inflammatory Bowel Diseases; Inflammatory Response; Intervention; Intestines; Ligands; Link; Lipids; Mediating; Membrane; Modeling; Mus; Mutant Strains Mice; Mutation; Nutrient; Pathogenesis; Pathology; Pathway interactions; Pattern recognition receptor; Peptidoglycan; Play; Population; Predisposition; Process; Protein Inhibition; Proteins; Regulation; Resistance; Resources; Role; Salmonella; Salmonella infections; Salmonella typhimurium; Signal Transduction; Source; Streptomycin; Testing; Therapeutic; Translations; Work; XBP1 gene; biological adaptation to stress; conditional mutant; dextran sulfate sodium induced colitis; endoplasmic reticulum stress; experimental study; gut inflammation; interest; intestinal epithelium; microbiota; monocyte; pathogen; protein complex; protein misfolding; receptor; release of sequestered calcium ion into cytoplasm; response; sphingosine 1-phosphate; tissue/cell culture

Project Summary NOD1 and NOD2 are Pattern Recognition Receptors that sense fragments of bacterial peptidoglycans, and are able to detect perturbations in cellular processes such as the regulation of the actin cytoskeleton and disturbance in endoplasmic reticulum (ER) homeostasis. Under different stressful conditions, such as bacterial infections, protein misfolding and perturbations in calcium homeostasis, the ER is unable to maintain homeostasis and activates the unfolded protein response (UPR). Within the UPR three transmembrane receptors, IRE1α, PERK and ATF6, are activated and regulate biological processes such as inhibition of protein translation, autophagy, and inflammation to reestablish cellular homeostasis. NOD1 and NOD2 have been implicated in ER stress- induced inflammation, by acting downstream of IRE1α in the UPR to induce inflammatory responses. This link between the UPR and NOD1/2 signaling is of particular interest in intestinal inflammation since mutations in genes associated with the UPR (XBP1) and innate immune signaling (NOD2) have been associated with intestinal epithelial cell (IEC) dysfunction in intestinal inflammatory diseases. Salmonella Typhimurium (S. Tm) is a gram-negative bacterium that induces robust inflammation, partially dependent on NOD1/2 activation, of the intestinal epithelium resulting in gastroenteritis. As a survival mechanism, S. Tm has adapted to these inflammatory conditions in the intestinal tract by utilizing products of inflammation as a nutrient source to outcompete the resident microbiota. Considering the importance of ER stress in intestinal inflammation and the fact that S. Tm is a major cause of gastroenteritis, it is surprising that ER stress in the context of Salmonella infections is significantly underexplored. Furthermore, it is currently unknown whether S. Tm can exploit ER stress-induced inflammation resulting in luminal expansion. Our objectives are to investigate the link between ER stress and inflammation in the S. Tm-induced colitis model. Our central hypothesis is that activation of the ER stress response in the gastrointestinal tract contributes significantly to S. Tm-induced inflammation, luminal expansion and pathology. We will test our hypothesis by pursuing the following three aims. 1) Determine the contribution of calcium flux and UPR activation to NOD1/2 signaling. In in vitro experiments we will determine which branches of the UPR, in conjunction with dysregulation of calcium signaling, contributes to NOD1/2 activation. 2) Determine the role of CHOP in the S. Tm-induced colitis model. Using Chop-/- mice and conditional mutant mice we will investigate the role of CHOP in S. Tm-induced inflammation and outgrowth. 3) Determine the role of NOD1/2 and IRE1α in response to S. Tm. We will investigate the role of IRE1α in Nod1/2-/- mice in the S. Tm-induced colitis model. Characterizing the mechanisms downstream of the UPR that orchestrate ER stress-induced responses is necessary to safely modulate this process for the development of future therapeutics and will significantly increase our understanding in Salmonella pathogenesis.

项目摘要 Nod1和NOD2是模式识别受体，可以感知细菌多聚糖片段，并能够检测细胞过程中的扰动，如肌动蛋白细胞骨架的调节和内质网(ER)动态平衡的紊乱。在不同的应激条件下，如细菌感染、蛋白质错误折叠和钙稳态的扰动，内质网无法维持稳态并激活未折叠蛋白反应(UPR)。在UPR中，三种跨膜受体，IRE1，α，PERK和ATF6被激活，并调节生物过程，如抑制蛋白质翻译，自噬， 和炎症来重建细胞内环境平衡。Nod1和Nod2参与了内质网应激诱导的炎症反应，它们作用于UPR中IRE1α下游，从而诱导炎症反应。UPR和NOD1/2信号之间的这种联系在肠道炎症中特别有意义，因为与UPR(XBP1)和天然免疫信号(NOD2)相关的基因突变与肠道炎症性疾病中的肠上皮细胞(IEC)功能障碍有关。鼠伤寒沙门氏菌(S.TM)是一种革兰氏阴性菌，能部分依赖于NOD1/2的激活，引起肠道上皮细胞的强烈炎症，从而导致胃肠炎。作为一种生存机制，S.TM已经适应了这些 通过利用炎症产物作为营养源来对抗肠道内的微生物群，从而改善肠道内的炎症状态。考虑到内质网应激在肠道炎症中的重要性，以及S.TM是胃肠炎的主要原因，令人惊讶的是，沙门氏菌感染背景下的内质网应激研究明显不足。此外，目前尚不清楚S.TM是否可以利用内质网应激诱导的炎症导致管腔扩张。我们的目标是在S.TM诱导的结肠炎模型中研究内质网应激和炎症之间的联系。我们的中心假设是，胃肠道内质网应激反应的激活对S.TM诱导的炎症、管腔扩张和病理有重要贡献。我们将通过追求以下三个目标来验证我们的假设。1)确定钙离子通量和UPR激活对NOD1/2信号转导的贡献。在体外实验中，我们将确定UPR的哪些分支，结合钙信号的失调，有助于NOD1/2的激活。2)确定CHOP在S.TM诱导的结肠炎模型中的作用。利用CHOP-/-小鼠和条件突变小鼠，我们将研究CHOP在S.TM诱导的炎症和生长中的作用。3)确定Nod1/2和Ire 1α在对S.TM的响应中的作用。我们将在S.TM诱导的结肠炎模型中研究IRE1α在Nod1/2-/-小鼠中的作用。描述UPR下游协调ER的机制 应激诱导的反应对于安全地调节这一过程对于未来治疗的发展是必要的，并将极大地增加我们对沙门氏菌发病机制的了解。