Anaplasma regulation of host granulocyte function

描述（由申请方提供）：人粒细胞无形体病（HGA）是一种由嗜吞噬细胞无形体（一种嗜中性粒细胞的专性细胞内细菌）引起的新发蜱媒疾病。A.嗜吞噬细胞菌感染通过转录重编程损害嗜中性粒细胞功能，其中重编程的嗜中性粒细胞促进新嗜中性粒细胞的炎性募集、组织损伤、炎症的无效调节和差的抗微生物应答。我们用A.本研究关注了嗜吞噬细胞菌感染，并关注了当核效应蛋白AnkA被递送到宿主细胞中时，它如何与受感染调节的基因的启动子结合，诱导表观遗传染色质重塑和转录重编程。粒细胞转录组与A.嗜吞噬细胞菌感染显示了许多促进感染的差异转录基因[3-6]。鉴于A.由于嗜吞噬细胞的存在，很难解释宿主转录变化的程度和单个易位效应蛋白的功能重编程。这意味着细菌可能通过靶向转录调控的保守机制（如细胞分化和肿瘤形成）对全局基因转录（包括染色质和组蛋白重塑）施加影响。AnkA具有提示作为基质附着区结合蛋白的功能的性质，其可以调节染色体区域对转录修饰物的访问，这是细菌-宿主相互作用的新范例。我们推测，AnkA结合到一些转录调控基因的启动子，并修改或招募修饰剂的表观遗传染色质标记或转录因子。此外，我们还假设A.嗜吞噬细胞菌通过AnkA对核基质、染色质和转录装置募集的作用改变表观基因组来重编程全局中性粒细胞转录组。我们提出以下目标：1.确定CYBB启动子中的AnkA结合位点，并确定参与CYBB启动子结合和转录活性的AnkA结构域或基序。2.确定AnkA是否通过直接作用于CYBB启动子或通过募集染色质重塑或转录因子影响宿主基因转录。3.确定AnkA是否作为一种基质附着区结合蛋白，将DNA束缚在核基质上，调节DNA环景，并允许其他染色质修饰剂在全局转录调控中对接。细菌对细胞转录的影响越来越被认识到。检验这些假说将为原核生物控制真核生物提供一个潜在的强大机制的证据。长期的目标是发展一个机械的理解如何细菌与亲密的宿主细胞协会规避宿主功能。这些信息可以允许合理的预防和治疗HGA，但也可以跨越生物学和医学，因为这些分子可以被设计为表观遗传工具或疗法。

DESCRIPTION (provided by applicant): Human granulocytic anaplasmosis (HGA) is an emerging tick-borne disease caused by Anaplasma phagocytophilum, an obligate intracellular bacterium of neutrophils. A. phagocytophilum infection impairs neutrophil function by transcriptional reprogramming, where the reprogrammed neutrophil promotes inflammatory recruitment of new neutrophils, tissue injury, ineffective regulation of inflammation, and poor antimicrobial responses. We studied altered neutrophil function with A. phagocytophilum infection and focused on how the nuclear effector protein AnkA, when delivered into the host cell where it binds to promoters of genes regulated with infection, induces epigenetic chromatin remodeling and transcriptional reprogramming. The granulocyte transcriptome with A. phagocytophilum infection shows a number of differentially transcribed genes that promote infection [3-6]. Given the meager genomic resources of A. phagocytophilum, it is difficult to explain the extent of host transcriptional change and functional reprogramming by individual translocated effector proteins. This implies that the bacterium exerts influence over global gene transcription, including chromatin and histone remodeling, perhaps by targeting conserved mechanisms of transcriptional regulation such as in cellular differentiation and neoplasia. AnkA has properties that suggest function as a matrix attachment region-binding protein that could regulate access of chromosomal territories to transcriptional modifiers, a new paradigm in bacteria-host interactions. We hypothesize that AnkA binds to promoters of some transcriptionally regulated genes and modifies or recruits modifiers of epigenetic chromatin marks or transcription factors. In addition, we hypothesize that A. phagocytophilum reprograms the global neutrophil transcriptome by altering the epigenome through AnkA"s action on nuclear matrix, chromatin, and transcriptional apparatus recruitment. We propose the following aims: 1. To identify AnkA binding sites in the CYBB promoter and to define AnkA domains or motifs involved in CYBB promoter binding and transcriptional activity. 2. To determine whether AnkA affects host gene transcription through direct action at the CYBB promoter or through recruitment of chromatin remodeling or transcription factors. 3. To determine whether AnkA functions as a matrix attachment region-binding protein that tethers DNA to nuclear matrix, regulates DNA loopscape, and permits docking of other chromatin modifiers in global transcriptional regulation. The effects that bacteria have over cellular transcription are increasingly recognized. Testing these hypotheses will provide evidence of a potentially powerful mechanism for prokaryotic control over eukaryotes. The long- term goals are to develop a mechanistic understanding of how bacteria with intimate host cell associations circumvent host functions. This information could allow rational preventions and therapies for HGA, but could also span biology and medicine, since such molecules could be engineered as epigenetic tools or therapies.