Molecular signaling in Shigella dissemination

志贺氏菌是世界范围内腹泻、痢疾和死亡的主要病原体， 通过结肠粘膜侵入和传播。志贺氏菌属为CDC/NIAID B类优先 病原体在诱导它们自己进入细胞后，细菌通过基于肌动蛋白的运动运动移动到细胞周边。 在细胞外围，它们向外挤压质膜，形成细胞延伸部分，被 未感染的相邻细胞，于是重复细胞到细胞传播的循环。 志贺氏菌和其他细胞内病原体通过激活正常宿主来增强感染过程 细胞信号通路。为了激活这些途径，这些微生物分泌到宿主细胞效应子中， 调节特定宿主蛋白质活性的蛋白质。而参与的分子信号事件 S.福氏志贺菌进入细胞的信号转导过程已被广泛研究。福氏 从一个细胞到相邻细胞的传播知之甚少。在本申请中，我们提出了一种 详细研究了S.弗氏细胞间播散， 使用靶向和全基因组方法。 我们的初步数据表明，细胞透明蛋白mDia 1和mDia 2， 在应力纤维形成途径中的功能，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S。为此需要弗氏菌蛋白IpgB 2、OspE 1和OspE 2 这些蛋白质触发部分冗余的宿主信号通路，可能涉及mDia 1 mDia2。此外，我们的数据表明，IpgB 2/OspE 1/OspE 2非依赖性机制也有助于 传播。我们的目标方法将测试IpgB 2，OspE 1和OspE 2激活的假设， 应力纤维形成途径中的具体步骤。我们的全基因组方法将检查人类 基因组的其他因素参与细胞间传播。我们的具体目标是： 1.对S. flexneri IpgB 2激活应力纤维形成途径; 2.对分泌型S.细胞间的弗氏效应蛋白OspE 1和OspE 2 传播;以及， 3.确定和表征S所需的其他宿主因素。使用全基因组的弗氏菌细胞间扩散 人siRNA筛选; 我们的方法不仅是为了深入了解所需的分子信号， S. flexneri，但也进入真核细胞的基本机制， 细胞间突起

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 Category B 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 genomewide 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.