Reprogramming of host cell cholesterol homeostasis by Coxiella burnetii

 描述（由申请方提供）：贝氏柯克斯体是人类Q热的病原体，Q热是一种新发传染病，也是培养阴性心内膜炎的主要原因。作为一种通过气溶胶传播的专性细胞内细菌病原体，柯克斯体在自然感染期间主要靶向肺泡巨噬细胞。一旦进入细胞，柯克斯体操纵宿主细胞机制，以促进一个专门的隔室称为寄生虫空泡（PV）的生物发生。虽然PV是柯克斯体发病机制的核心，但PV生物发生和维持背后的机制知之甚少。柯克斯体PV富含固醇，干扰宿主细胞胆固醇的药物抑制剂抑制PV形成和随后的细菌生长。尽管越来越多的证据表明胆固醇在PV形成和考克斯体与宿主相互作用中发挥着关键作用，但关于胆固醇和考克斯体与宿主相互作用的信息却很少。 涉及细菌或宿主因素。本申请的目的是鉴定和表征宿主细胞胆固醇稳态中细菌驱动的变化。该提案将测试以下假设：Coxiella蛋白通过细菌的专门的IV型分泌系统（T4SS）分泌到宿主细胞质中，操纵宿主胆固醇稳态作为支持细胞内细菌生长和存活的机制。在第一个具体目标中，将通过感染的肺泡巨噬细胞的转录组分析来鉴定Coxiella T4SS效应蛋白靶向的宿主胆固醇稳态途径。这项研究将确定关键的宿主细胞基因的差异调节柯克斯体。鉴定后，将破坏宿主途径，并确定对柯克斯体存活的影响。在第二个目标中，将表征操纵宿主胆固醇的Coxiella蛋白。这将通过筛选已经失去改变宿主细胞胆固醇稳态能力的Coxiella转座子突变体来实现。将通过分析分离的突变体的表型以及相应蛋白质的功能分析来表征鉴定的柯克斯体蛋白质。拟议的工作将确定宿主和病原体蛋白参与胆固醇稳态在柯克斯体感染，开辟新的途径进行治疗干预。

 DESCRIPTION (provided by applicant): Coxiella burnetii is the causative agent of human Q fever, an emerging infectious disease and a leading cause of culture-negative endocarditis. An obligate intracellular bacterial pathogen spread through aerosols, Coxiella primarily targets alveolar macrophages during natural infection. Once inside the cell, Coxiella manipulates host cell machinery to promote the biogenesis of a specialized compartment called the parasitophorous vacuole (PV). While the PV is central to Coxiella pathogenesis, the mechanisms behind PV biogenesis and maintenance are poorly understood. The Coxiella PV is sterol-rich, and pharmaceutical inhibitors that perturb host cell cholesterol inhibit PV formation and subsequent bacterial growth. Despite increasing evidence that cholesterol plays a critical role in PV formation and Coxiella-host interactions, there is very little information on either the bacterial or host factors involved. The objective of this application is to identify and characterie bacterial-driven changes in host cell cholesterol homeostasis. This proposal will test the hypothesis that Coxiella proteins, secreted into the host cell cytoplasm through the bacteria's specialized Type IV Secretion System (T4SS), manipulate host cholesterol homeostasis as a mechanism to support intracellular bacterial growth and survival. In the first specific aim, host cholesterol homeostasis pathways targeted by Coxiella T4SS effector proteins will be identified through transcriptome analysis of infected alveolar macrophages. This study will identify key host cell genes differentially regulated by Coxiella. Following their identification, the host pathways will be disrupted and the effect on Coxiella survival determined. In the second aim, Coxiella proteins that manipulate host cholesterol will be characterized. This will be accomplished by screening for Coxiella transposon mutants that have lost the ability to alter host cell cholesterol homeostasis. The identified Coxiella proteins will be characterized by analyzing the phenotype of the isolated mutants, as well as functional analysis of the corresponding protein. The proposed work will identify both host and pathogen proteins involved in cholesterol homeostasis during Coxiella infection, opening new avenues for therapeutic intervention.