Modulation of host Apoptotic pathways by Legionella pneumophila

我们的目标是了解细胞内病原体嗜肺军团菌如何操纵宿主细胞 功能，以促进其增殖，从而为设计新的治疗策略提供知识 用于治疗传染病。胞内生长。嗜肺菌需要Dot/lcm蛋白 将细菌效应物转移到受感染细胞中的分泌系统。这些效应器被认为 调节宿主细胞功能以建立支持细菌复制的小生境。我们 具体的假设是，在感染期间，SidF，Dot/lcm系统的底物，积极地阻止 感染的细胞进行凋亡。这一假设基于四个观察结果：1）细胞凋亡是 启动于L.嗜肺细胞，但细胞不广泛凋亡; 2)感染BNF突变体的巨噬细胞比感染野生型细菌的巨噬细胞凋亡更多; 3） SidF与两种促凋亡蛋白BNIP 3和Bcl-rambo相互作用; 4）表达SidF的细胞具有抗性 与这些促死亡蛋白或化学试剂诱导的细胞凋亡有关。我们的具体目标是： 1.对一个BMPF突变体的感染表型进行彻底的分析。我们将审查（i）是否 BNF突变体在获得内质网标记方面有缺陷，（ii）BNF是否是获得内质网标记所必需的。 胞内生长嗜肺细胞在其他类型的宿主细胞和（iii）原代细胞的凋亡反应 突变体感染的巨噬细胞，（iv）Bcl-rambo的耗竭如何影响细菌的胞内生长。 2.分析SidF和促凋亡蛋白BNIP 3之间的相互作用，以及这种相互作用是如何 影响湖嗜肺菌胞内生长。我们将研究（i）SidF对亲- 凋亡蛋白BNI PS介导的凋亡，（ii）BNI PS介导的凋亡如何影响细胞内生长 乳pneumophila和（iii）SidF如何干扰BNIP 3活性的机制。 3.识别L.在调节宿主功能中与SidF协同作用的嗜肺菌效应子。我们 将鉴定（i）与BNIP 3相互作用的非SidF效应物，（ii）在BNIP 3中细胞内生长所必需的蛋白质， SidF缺失突变体背景和（iii）与SidF特异性相互作用以形成多- 成分效应复合体

Our goal is to understand how the intracellular pathogen Legionella pneumophila manipulates host cellular functions to facilitate its multiplication, thus to provide knowledge for designing novel therapeutic strategies for treating infectious diseases. Intracellular growth of L. pneumophila requires the Dot/lcm protein secretion system that translocates bacterial effectors into infected cells. These effectors are believed to modulate host cellular functions for the establishment of a niche that supports bacterial replication. Our specific hypothesis is that during infection, SidF, a substrate of the Dot/lcm system actively prevents infected cells from undergoing apoptosis. This hypothesis is based on four observations: 1) Apoptosis is initiated in permissive macrophages infected by L. pneumophila but the cells are not extensively apoptotic; 2) Macrophages infected by a sidF mutant are more apoptotic than those infected by wild-type bacterium; 3) SidF interacts with two pro-apoptotic proteins, BNIP3 and Bcl-rambo; 4) Cells expressing SidF are resistant to apoptosis induced by these pro-death proteins or chemical agents . Our specific aims are to: 1. Perform a thorough analysis of infection phenotypes of a sidF mutant. We will examine (i) whether the sidF mutant is defective in acquiring endoplasmic reticulum markers, (ii)whether sidF is required for intracellular growth of L. pneumophila in other types of host cells and (iii) apoptotic response of primary macrophages infected by the mutant, (iv)how depletion of Bcl-rambo affects bacterial intracellulargrowth. 2. Analyze the interactions between SidF and the pro-apoptotic protein BNIP3 and how such interactions affect L. pneumophila intracellular growth. We will examine (i) the effect of SidF binding on the pro- apoptotic protein BNI PS-mediated apoptosis, (ii) how BNI PS-mediated apoptosis affects intracellular growth of L. pneumophila and (iii)the mechanisms of how SidF interferes with the activity of BNIP3. 3. Identify L. pneumophila effector(s) that function synergistically with SidF in modulating host functions. We will identify (i) non-SidF effectors that interact with BNIP3, (ii) proteins necessary for intracellular growth in the sidF deletion mutant background and (iii)proteins that specifically interact with SidF to form a multi- component effector complex.