Mechanisms of Rickettsia invasion, intracellular survival, and actin-based motility

立克次体侵袭、细胞内存活和基于肌动蛋白的运动的机制

• 批准号: 9615323
• 负责人: Matthew D Welch
• 金额: $ 38.18万
• 依托单位: UNIVERSITY OF CALIFORNIA BERKELEY
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-09-01 至 2023-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9615323
• 关键词: Actins; Address; Automobile Driving; Autophagocytosis; Bacteria; Bacterial Physiology; Cell Surface Receptors; Cells; Cellular Structures; Cellular biology; Cytoskeleton; Cytosol; Diagnosis; Diagnostic; Disease; Fever; Funding; Genes; Genome; Growth; Human; In Vitro; Infection; Invaded; Knowledge; Lead; Mediating; Membrane; Membrane Proteins; Molecular; Mus; Mutagenesis; Mutation; Nutrient; Pathogenesis; Phagosomes; Phase; Phenotype; Phospholipase; Play; Polymers; Process; Proteins; Publishing; Rickettsia; Rickettsia Infections; Role; Study models; Surface Antigens; Testing; Typhus; Virulence; Work; bacterial genetics; base; cell motility; human disease; improved; in vivo; innovation; macrophage; mouse model; mutant; novel strategies; pathogen; polymerization; receptor; ubiquitin ligase; unpublished works

PROJECT SUMMARY/ABSTRACT The Rickettsiae are obligate intracellular bacterial pathogens that cause serious diseases, such as spotted fever and typhus. We study the model spotted fever group (SFG) species Rickettsia parkeri, which causes an eschar-associated human rickettsiosis, is experimentally tractable, and has emerging mouse models of pathogenesis, making it ideal for revealing molecular mechanisms of SFG Rickettsia infection and virulence. During infection, SFG Rickettsia invade host cells by mobilizing the actin cytoskeleton, escape from the phagosome into the cytosol, replicate while avoiding degradation by autophagy, and harness actin polymerization to promote intracellular motility and cell-cell spread. However, there are fundamental gaps in our knowledge of the molecular mechanisms by which SFG Rickettsia exploit or disrupt host cell components to promote their infection cycle. To bridge these gaps, in the current funding period we have pioneered an innovative combination of bacterial genetics and host cell biology to identify key Rickettsia factors that manipulate host cells. In unpublished work, we discovered that outer membrane protein OmpB is crucial for both invasion and avoidance of autophagy. We also observed that patatin-like phospholipase Pat1 plays a role in phagosome escape and/or autophagy evasion. Additionally, in published work, we demonstrated that Rickettsia use two actin-polymerizing surface proteins to direct sequential phases of motility – with RickA driving early motility and surface cell antigen Sca2 driving late motility. However, key outstanding questions remain, including: How do Rickettsia engage host receptors to promote invasion? How do Rickettsia degrade membranes during phagosome escape or inhibit membrane engulfment to avoid autophagy? And how do Rickettsia coordinate and use two actin assembly factors in distinct phases of motility? Our preliminary and published findings suggest the overall hypothesis that OmpB, Pat1, RickA, and Sca2 are multifunctional proteins that mobilize or disrupt host cell components and play a crucial role in infection in vivo. This hypothesis will be tested in three Aims focused on uncovering the mechanisms through which OmpB, Pat1, RickA, and Sca2 influence invasion, intracellular survival, and motility. The Aims are to: (1) define the role of Rickettsia surface protein OmpB in invasion and intracellular survival; (2) investigate the role of Pat1 phospholipase in phagosome escape and intracellular survival; and (3) determine how and why Rickettsia use two distinct actin-based motility mechanisms. The proposed studies will advance the field by revealing crucial molecular mechanisms used by Rickettsia and other pathogens to manipulate host cells and the importance of these mechanisms to infectivity. Our studies may also lead to improved diagnostics and treatments for rickettsial and other infections.

项目摘要/摘要 立克西亚是义务引起严重疾病的义务细胞内细菌病原体，例如发现 发烧和斑疹伤寒。我们研究模型发现发烧组（SFG）物种立克帕克里（Rickettsia Parkeri），这导致 与埃斯查（Eschar）相关的人体力学，在实验上是可进行的，并且具有新兴的小鼠模型 发病机理，使其成为揭示SFG人力素感染和病毒的分子机制的理想选择。 在感染期间，SFG人力素症通过动员肌动蛋白细胞骨架侵入宿主细胞，逃脱 吞噬入细胞质的吞噬体，在避免自噬降解的同时复制，并采用肌动蛋白 聚合以促进细胞内运动和细胞细胞扩散。但是，有根本的差距 我们对SFG人力素剥削或破坏宿主细胞成分的分子机制的了解 促进其感染周期。为了弥合这些差距，在当前的资金期间，我们开创了 细菌遗传学和宿主细胞生物学的创新组合，以识别重力体力学因素 操纵宿主细胞。在未发表的工作中，我们发现外膜蛋白OMPB对 入侵和避免自噬。我们还观察到patatin样磷脂酶PAT1起作用 在吞噬体逃生和/或自噬进化中。此外，在已发表的工作中，我们证明了 人力病患者使用两种肌动蛋白聚合表面蛋白来引导运动的顺序阶段 - ricka 驱动早期运动能力和表面细胞抗原SCA2驱动晚期运动。但是，关键的杰出问题 保留，包括：Rickettsia如何让主持人接收者促进入侵？人力车如何降解 吞噬体逃生期间的膜或抑制膜吞噬以避免自噬？以及如何 人力车协调并在运动的不同阶段使用两个肌动蛋白组装因子？我们的初步和 已发表的发现表明了总体假设，即OMPB，PAT1，Ricka和Sca2是多功能的 动员或破坏宿主细胞成分并在体内感染中起关键作用的蛋白质。这 假设将以三个目的进行检验，旨在发现OMPB，PAT1， Ricka和Sca2影响入侵，细胞内存活和运动。目的是：（1）定义 立克表面蛋白OMPB在入侵和细胞内存活中； （2）调查PAT1的作用 吞噬体逃生和细胞内存活中的磷脂酶； （3）确定立克的方法以及为什么使用 两种不同的基于肌动蛋白的运动机制。拟议的研究将通过揭示至关重要 立克和其他病原体使用的分子机制来操纵宿主细胞以及 这些机制是感染的。我们的研究也可能导致改进的诊断和治疗方法 立克和其他感染。