Cytoskeletal-Pathogen Interactions in Shigella Infection

志贺氏菌感染中的细胞骨架-病原体相互作用

• 批准号: 7161772
• 负责人: Scott B Snapper
• 金额: $ 40.32万
• 依托单位: MASSACHUSETTS GENERAL HOSPITAL
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-09-15 至 2009-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7161772
• 关键词: Actins; Bacteria; Binding; Biological Products; Categories; Cell Line; Cell Surface Extensions; Cell physiology; Cells; Cicatrix; Collaborations; Complex; Cytoplasm; Cytoskeleton; DNA Sequence Rearrangement; Disease; Disruption; Epithelial Cells; Epithelium; Family; Family member; Fibroblasts; Filopodia; Generations; Genetic; Goals; Guanosine Triphosphate Phosphohydrolases; IcsA protein; Infection; Knock-out; Laboratories; Link; Lymphocyte; Mammalian Cell; Mediating; Membrane; Membrane Proteins; Minor; Molecular; Mouse Cell Line; Mucous Membrane; Mutation; Object Attachment; Organism; Pathogenesis; Pathway interactions; Process; Protein Binding; Protein Family; Proteins; Receptor Signaling; Regulation; Research Personnel; Role; Shapes; Shigella; Shigella Infections; Signal Pathway; Signaling Molecule; Structure; Surface; Tail; Testing; Wiskott-Aldrich Syndrome; cdc42 GTP-Binding Protein; cell motility; enteric pathogen; microbial; novel; pathogen; rac GTP-Binding Proteins; rho

Shigella are gram negative enteric pathogens that cause severe diarrheal disease and have been classified as a Category B Biological Agent. Shigella pathogenesis requires bacterial invasion of the colonic epithelium and bacterial spread through the colonic mucosa. Shigella entry into epithelial cells is mediated by effector molecules, secreted through a type III secretion apparatus, that activate Rho family GTPase signaling pathways to induce the formation of cell surface projections and membrane ruffles that engulf the bacteria by macropinocytosis. Both Cdc42 and Rac have been implicated as having a role in the Shigella entry process. Cdc42 is known to activate Rac; it is not clear whether Cdc42 involvement in Shigella entry is mediated exclusively via this link. Moreover, the downstream effectors of Cdc42 and/or Rac activation during Shigella entry are unknown. We have recently confirmed that the major Shigella pathway is Cdc42-dependent. However, we have also demonstrated the existence of a novel Cdc42-independent invasion pathway. Furthermore we have shown that the only known downstream effector of Cdc42 that activates the actin cytoskeleton, N-WASP, is not involved in Shigella entry. Once in the cytoplasm, Shigella moves by active assembly of an actin tail. Actin tail formation is mediated by the Shigella outer membrane protein IcsA, which binds and activates N-WASP. Activated N-WASP stimulates Arp2/3 complex-mediated actin assembly. The molecular mechanism by which IcsA binds and activates N-WASP is poorly understood. Our goals in this proposal are to: 1. Define the specific roles of Cdc42 and Rac in Shigella entry; 2. Identify and characterize the downstream effectors of Rho family activation during Shigella entry; and, 3. Elucidate the mechanism(s) by which Shigella IcsA activates N-WASP and determine whether this mechanism mimics Cdc42 activation of N-WASP These studies will define the specific cellular signaling pathways required for Shigella entry and actin tail formation and will identify downstream pathways of Rho family activation.

志贺氏菌是一种革兰氏阴性肠道病原体，可导致严重的腹泻疾病，一直以来 被列为B类生物制剂。志贺氏菌的致病需要细菌入侵 结肠上皮和细菌通过结肠粘膜扩散。志贺氏菌进入上皮细胞 是由效应分子介导的，通过III型分泌器分泌，激活Rho 诱导细胞表面突起和膜形成的家族GTPase信号通路 因巨噬细胞增多而吞噬细菌的褶皱。Cdc42和RAC都被牵连为 在志贺氏菌进入过程中发挥作用。已知CDC42可激活RAC；目前尚不清楚 CDC42参与志贺氏菌的进入完全通过这个链接。而且，下游 志贺氏菌进入过程中，CDC42和/或RAC激活的效应器尚不清楚。我们最近做了 证实志贺氏菌的主要途径是依赖于Cdc42。然而，我们也展示了 存在一条新的CDC42非依赖的侵袭途径。此外，我们已经证明了 只有已知的激活肌动蛋白细胞骨架的CDC42下游效应子N-WASP不是 参与了志贺氏菌的进入。志贺氏菌一旦进入细胞质，就会通过主动组装肌动蛋白尾巴来移动。 肌动蛋白尾部的形成是由志贺氏菌外膜蛋白ICSA介导的，该蛋白结合并激活 N-WASP.活化的N-WASP刺激Arp2/3复合体介导的肌动蛋白组装。分子 ICSA结合和激活N-WASP的机制尚不清楚。 我们在这项建议中的目标是： 1.明确CDC42和Rac在志贺氏菌进入中的具体作用； 2.确定和鉴定志贺氏菌进入过程中Rho家族激活的下游效应因子； 和, 3.阐明ICSA志贺氏菌激活N-WASP的机制(S)，并确定这是否 N-WASP对CdC42活化的模拟机理 这些研究将确定志贺氏菌进入和肌动蛋白所需的特定细胞信号通路。 并将确定Rho家族激活的下游途径。