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 NOD 1和NOD 2是模式识别受体，其感测细菌肽聚糖的片段，并且能够检测细胞过程中的扰动，例如肌动蛋白细胞骨架的调节和内质网（ER）稳态的扰动。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，ER不能维持稳态并激活未折叠蛋白反应（UPR）。在UPR中，三种跨膜受体IRE 1 α、PERK和ATF 6被激活并调节生物学过程，如抑制蛋白质翻译、自噬、 和炎症来重建细胞内稳态。NOD 1和NOD 2通过在UPR中作用于IRE 1 α下游以诱导炎症反应而参与ER应激诱导的炎症。UPR和NOD 1/2信号之间的这种联系在肠道炎症中特别令人感兴趣，因为与UPR（XBP 1）和先天免疫信号（NOD 2）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）是一种革兰氏阴性细菌，其诱导肠上皮的强烈炎症，部分依赖于NOD 1/2活化，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以胜过驻留的微生物群来治疗肠道中的炎性病症。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，在沙门氏菌感染的背景下，ER应激显着不足。此外，目前尚不清楚S。Tm可以利用ER应激诱导的炎症，导致管腔扩张。我们的目标是研究在S. TM诱导的结肠炎模型。我们的中心假设是胃肠道ER应激反应的激活对S。肿瘤诱导的炎症反应、管腔扩张及病理学改变。我们将通过追求以下三个目标来检验我们的假设。1)确定钙流和UPR激活对NOD 1/2信号传导的贡献。在体外实验中，我们将确定UPR的哪些分支，以及钙信号的失调，有助于NOD 1/2激活。2)确定CHOP在S. TM诱导的结肠炎模型。使用Chop-/-小鼠和条件突变小鼠，我们将研究CHOP在S.结核分枝杆菌引起的炎症和增生。3)确定NOD 1/2和IRE 1 α在S. TM.我们将研究IRE 1 α在Nod 1/2-/-小鼠中在S. TM诱导的结肠炎模型。描述普遍定期审议下游协调紧急救济的机制 应激诱导的反应对于安全地调节该过程以用于未来治疗剂的开发是必要的，并且将显著增加我们对沙门氏菌发病机理的理解。