Molecular signaling in Shigella dissemination

志贺氏菌传播中的分子信号传导

• 批准号: 8500667
• 负责人: Marcia B Goldberg
• 金额: $ 3.77万
• 依托单位: MASSACHUSETTS GENERAL HOSPITAL
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-01-01 至 2014-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8500667
• 关键词: Actins; Bacteria; Binding; Biochemical; Biological; C-terminal; Cell Cycle; Cell membrane; Cell surface; Cells; Cellular Stress; Centers for Disease Control and Prevention (U.S.); Cytolysis; Data; Development; Diarrhea; Disease; Dysentery; Effector Cell; Event; Focal Adhesions; Genes; Human; Human Cell Line; Human Genome; Infection; Integration Host Factors; Interphase Cell; Intestines; Invaded; Investigation; Lead; Modeling; Molecular; Movement; Mucous Membrane; N-terminal; National Institute of Allergy and Infectious Disease; Open Reading Frames; Organism; Pathogenesis; Pathway interactions; Process; Proteins; RNA Interference; Role; Shigella; Shigella flexneri; Shigella sonnei; Signal Pathway; Signal Transduction; Site; Small Interfering RNA; Stress Fiber Formation Pathway; Stress Fibers; Tail; Testing; Therapeutic; Tissues; Vacuole; base; cell motility; design; genome wide association study; genome-wide; human tissue; improved; insight; microorganism; monolayer; mortality; pathogen; public health relevance; response

DESCRIPTION (provided by applicant): Shigella, a major etiologic agent of diarrhea, dysentery, and mortality worldwide, causes disease by invading and disseminating through the colonic mucosa. Shigella sp. are CDC/NIAID priority pathogens. After inducing their own entry into cells, bacteria move to the cell periphery by actin-based motility. At the cell periphery, they push out against the plasma membrane, forming cell extensions that are engulfed by uninfected adjacent cells, whereupon the cycle of cell-to-cell dissemination is repeated. Shigella and other intracellular pathogens enhance the process of infection by activating normal host cell signaling pathways. To activate these pathways, these microorganisms secrete into the host cell effector proteins that modulate the activity of specific host proteins. Whereas the molecular signaling events involved in S. flexneri entry into cells have been studied extensively, the signaling events involved in S. flexneri dissemination from one cell into an adjacent cell are poorly understood. In this application, we propose a detailed investigation of the molecular signaling events that occur during S. flexneri intercellular dissemination, using both targeted and genome-wide approaches. Our preliminary data indicate that the cellular diaphanous formin proteins mDia1 and mDia2, which function in the stress fiber formation pathway, are required for efficient dissemination through cell monolayers. Our data also indicate that the secreted S. flexneri proteins IpgB2, OspE1, and OspE2 are required for this process and that these proteins trigger partially redundant host signaling pathways that likely involve mDia1 and mDia2. In addition, our data indicate that IpgB2/OspE1/OspE2-independent mechanisms also contribute to dissemination. Our targeted approaches will test the hypothesis that IpgB2, OspE1, and OspE2 activate specific steps in the stress fiber formation pathway. Our genome-wide approach will examine the human genome for additional factors involved in intercellular dissemination. Our specific aims are: 1. Characterize the mechanisms of S. flexneri IpgB2 activation of the stress fiber formation pathway; 2. Characterize the roles of secreted S. flexneri effector proteins OspE1 and OspE2 in intercellular dissemination; and, 3. Identify and characterize other host factors required for S. flexneri intercellular spread using a genome- wide human siRNA screen; Our approaches are designed to generate insights not only into the molecular signaling that is required for intercellular dissemination of S. flexneri, but also into fundamental mechanisms of eukaryotic cellular and intercellular processes. PUBLIC HEALTH RELEVANCE: The human pathogen Shigella is a bacterium that causes diarrhea by infecting cells that line the human intestinal tract and disseminating through intestinal tissue by mechanisms that are poorly understood. The bacterium promotes dissemination by producing molecules that trigger specific responses in the infected cells that enhance the movement of bacteria into adjacent uninfected cells; we propose detailed studies into the molecular signaling involved in the dissemination of Shigella through tissue. Our results could lead to an improved understanding of how pathogens interact with human tissue and the development of better therapeutics.

描述(申请人提供)：志贺氏菌是世界范围内腹泻、痢疾和死亡的主要病原体，通过结肠粘膜入侵和传播而导致疾病。志贺氏菌属是CDC/NIAID的优先病原体。在诱导自己进入细胞后，细菌通过基于肌动蛋白的运动向细胞外围移动。在细胞外围，它们向外挤向质膜，形成细胞延伸，被未感染的相邻细胞吞噬，从而重复细胞到细胞的传播周期。志贺氏菌和其他细胞内病原体通过激活正常的宿主细胞信号通路来增强感染过程。为了激活这些途径，这些微生物分泌到宿主细胞的效应器蛋白中，调节特定宿主蛋白的活性。虽然福氏志贺氏菌进入细胞的分子信号事件已经被广泛研究，但涉及福氏志贺菌从一个细胞传播到相邻细胞的信号事件却知之甚少。在这一应用中，我们建议对福氏志贺氏菌在细胞间传播过程中发生的分子信号事件进行详细的调查，使用靶向和基因组范围的方法。我们的初步数据表明，在应力纤维形成途径中发挥作用的细胞透明福尔曼蛋白mDia1和mDia2是通过细胞单层有效传播所必需的。我们的数据还表明，分泌的福氏杆菌蛋白IpgB2、OspE1和OspE2是这一过程所必需的，这些蛋白触发了部分冗余的宿主信号通路，可能涉及mDia1和mDia2。此外，我们的数据表明，IpgB2/OspE1/OspE2独立的机制也有助于传播。我们有针对性的方法将测试IpgB2、OspE1和OspE2激活应力纤维形成途径中特定步骤的假设。我们的全基因组方法将检查人类基因组，以寻找参与细胞间传播的其他因素。我们的具体目标是：1.表征福氏志贺氏菌IpgB2激活应力纤维形成途径的机制；2.表征分泌的福氏志贺氏菌效应蛋白OspE1和OspE2在细胞间传播中的作用；以及3.使用全基因组的人类siRNA筛选来识别和表征福氏志贺氏菌细胞间传播所需的其他宿主因素；我们的方法旨在不仅深入了解福氏志贺菌细胞间传播所需的分子信号，而且深入了解真核细胞和细胞间过程的基本机制。 与公共卫生相关：人类病原体志贺氏菌是一种通过感染人体肠道细胞并通过肠道组织传播的细菌，其机制尚不清楚。这种细菌通过产生分子来促进传播，这些分子在受感染的细胞中触发特定的反应，促进细菌进入邻近的未感染细胞；我们建议对志贺氏菌通过组织传播所涉及的分子信号进行详细研究。我们的结果可能有助于更好地理解病原体与人体组织的相互作用，并开发更好的治疗方法。