Cellular Biology Of Host/parasite Interactions

宿主/寄生虫相互作用的细胞生物学

• 批准号: 7964301
• 负责人: David (Ted) Hackstadt
• 金额: $ 119.3万
• 依托单位: NATIONAL INSTITUTE OF ALLERGY AND INFECTIOUS DISEASES
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/7964301
• 关键词: Actins; Affinity; Anabolism; Animals; Area; Atherosclerosis; Bacterial Infections; Basic Science; Blindness; Carcinoma; Cell Cycle Regulation; Cell membrane; Cells; Cellular biology; Centrosome; Chlamydia; Chlamydia Infections; Chlamydia trachomatis; Chlamydophila pneumoniae; Chlamydophila psittaci; Cholesterol; Chromatin; Chromosomal Instability; Cytoplasm; DNA; DNA Structure; Defect; Development; Dynein ATPase; Eligibility Determination; Endosomes; Epidemiology; Escherichia coli; Event; Failure; Gene Expression; Genetic Transcription; Golgi Apparatus; Growth; Histone H1; Histone H1(s); Histones; Human; Immunologics; Infection; Intervention; Link; Malignant Neoplasms; Malignant neoplasm of cervix uteri; Medical; Membrane; Membrane Proteins; Microtubule-Organizing Center; Microtubules; Minus End of the Microtubule; Modification; Molecular; Molecular and Cellular Biology; Motor; Mutation; Oncogenes; Outcome; Parasites; Pathway interactions; Play; Positioning Attribute; Process; Proteins; Proteomics; RNA; Recycling; Regulation; Role; Screening procedure; Sexually Transmitted Diseases; Specificity; Sphingomyelins; Staging; Study Section; Time; Trachoma; Transferrin; Translations; Type III Secretion System Pathway; Tyrosine; Upper Respiratory Infections; Vacuole; Viral; Weight; extracellular; human disease; improved; insight; isoprenoid; mevalonate; novel; pathogen; protein protein interaction; receptor; response; trafficking; tumor

Chlamydia trachomatis is the etiological agent of several significant diseases of humans including trachoma, the leading cause of infectious blindness worldwide. It is also the most common cause of sexually transmitted disease in the USA. Other species of medical importance include C. pneumoniae, a causative agent of upper respiratory tract infections and possibly associated with atherosclerosis, and C. psittaci, which is primarily a pathogen of animals but occasionally is transmitted to humans. The Host-Parasite Interactions Section studies the fundamental cellular and molecular biology of intracellular pathogens. Efforts have been primarily with the genus Chlamydia and include two basic research areas: i.) the cellular interactions that promote entry and intracellular growth; primarily those controlled by secreted chlamydial effector proteins and ii.) global regulation of chlamydial gene expression by histone-like proteins. Establishment of a protected intracellular niche is a critical stage of the chlamydial developmental cycle. We have therefore focused much of our efforts over the last several years upon events occurring within these early stages of infection. Many of these events are unique among intracellular pathogens but common to the genus Chlamydia. The experimental approaches are heavily weighted toward cell biology, proteomics, and functional analysis of protein-protein interactions. An improved understanding of the distinct developmental stages and the cellular responses to them may suggest novel means of chemotherapeutic or immunologic intervention of chlamydial diseases. Chlamydiae occupy a unique vacuolar niche within the host cell. The chlamydial inclusion, unlike vacuoles containing other intracellular pathogens, is not interactive with endocytic vesicular trafficking pathways but is instead fusogenic with an incompletely understood exocytic pathway which delivers sphingomyelin and cholesterol from the Golgi apparatus to the plasma membrane. Entry into this pathway is an active process on the part of the chlamydiae as both de novo transcription and translation are required. Virtually all of these interactions are specific and localized to the inclusion. This specificity strongly suggests modification of the exposed inclusion membrane. Examples of cis-acting modifications to the nascent inclusion membrane include: evasion of lysosomal fusion, interactions with microtubules to deliver the nascent inclusion to the peri-Golgi region and microtubule organizing center, initiation of fusion with exocytic vesicular traffic from the Golgi apparatus, and recruitment of, but not fusion with, recycling endosomes containing transferrin and its receptor. Many of these interactions are temporally associated with the exposure of inclusion membrane proteins to the host cell cytoplasm by a chlamydial type III secretion system. Another example of a chlamydial proteins controlling localized events could include the recruitment of actin to promote entry. A type III secreted protein, termed Tarp, is translocated and tyrosine phosphorylated while EBs are still extracellular. Tarp has been associated with the actin recruitment which is required for chlamydial internalization. Chlamydial Tarp and the inclusion membrane proteins define at least two distinct stages in chlamydial development where secreted effectors may play important roles in defining the outcome of infection. In the case of Tarp, a pre-existing effector protein is secreted across the plasma membrane from extracellular EBs, while inclusion membrane proteins require de novo synthesis and are secreted across the inclusion membrane from the RBs within. Identification of secreted effector molecules and their functions will continue to provide insights into the many adaptations chlamydiae utilize as successful pathogens. Nascent chlamydial inclusions migrate towards the minus end of microtubules and aggregate at the MTOC utilizing the minus-end-directed microtubule motor dynein. This interaction leads to disruption of normal centrosomal positioning leading to centrosome number defects. The association of the chlamydial inclusion membrane with centrosomes leads to failures in centrosomal partitioning and/or cytokinesis.Centrosome supernumerary defects have been implicated in chromosome instability and loss of cell cycle control in early tumors and most aggressive carcinomas. The hypothesis that bacterial infections can contribute to cancer has endured for some time, but unlike viral induced cancers, specific oncogenes and molecular mechanisms have not been clearly established. The interaction of chlamydiae with dynein and centrosomes suggests a mechanism by which chlamydial infection, through induction of abnormal centrosome numbers, may be a contributing factor in chromosome instability ultimately leading to transformation and tumor development. Chlamydial histone H1-like proteins, Hc1 and Hc2, act as globalregulators of chlamydial gene expression by virtue of dramatic effects on DNA structure. The chlamydial histones are transcribed late in the developmental cycle as RBs differentiate to EBs. The mechanisms of histone release from the chlamydial chromatin at the initiation of development had been unknown. By utilizing a heterologous screening protocol in E. coli, we identified two novel means of regulation of histone activity. The affinity of histone for DNA appears to be disrupted early in infection by the synthesis of a small metabolite in the non-mevalonate pathway of isoprenoid biosynthesis. In the course of the screening procedure, we also identified a small regulatory RNA that specifically inhibits translation of Hc1.

沙眼衣原体是几种重大疾病人类的病因学药，包括沙丘瘤，这是全球感染性失明的主要原因。它也是美国性传播疾病的最常见原因。医学重要性的其他物种包括肺炎C.肺炎，这是上呼吸道感染的原因，可能与动脉粥样硬化有关，而C. psittaci则主要是动物的病原体，但偶尔会传播给人类。 宿主 - 寄生虫相互作用部分研究了细胞内病原体的基本细胞和分子生物学。 努力主要与衣原体属有关，包括两个基础研究领域：i。）促进进入和细胞内生长的细胞相互作用；主要是由分泌的衣原体效应子蛋白和II控制的。 建立受保护的细胞内生态位是衣原体发育周期的关键阶段。 因此，在过去几年中，我们将大部分努力集中在感染的早期阶段内发生的事件。 这些事件中的许多事件在细胞内病原体中是独一无二的，但衣原体共有。 实验方法对细胞生物学，蛋白质组学和蛋白质 - 蛋白质相互作用的功能分析都大大加权。 对不同的发育阶段和对它们的细胞反应的改进理解可能表明衣原体疾病的化学治疗或免疫学干预的新型手段。 衣原体在宿主细胞中占据了独特的液泡生态位。 与含有其他细胞内病原体的液泡不同，衣原体的包含与内吞囊泡运输途径没有相互作用，而是fusogenic却具有未完全理解的外co型途径，从而传达了鞘磷脂和胆固醇从高脂蛋白剂到果仁糖从plasmammambrane中。 进入该途径是衣原体的一个积极过程，因为需要从头转录和翻译。 几乎所有这些相互作用都是特定的，并且本地化为包容性。 该特异性强烈表明对暴露的纳入膜的修饰。 对新生纳入膜进行顺式作用修饰的实例包括：逃避溶酶体融合，与微管的相互作用，以向高尔基细胞区域和微管组织中心提供新生的包容性，与外粒囊泡融合的融合启动，但与Golgi的融合，但不是与Golgi的转移和招募，但不是，但不是Recrition flosing flosing flosing flosing fromperife flosing of froming soff from frop，and Recrition of Recrition of from from，它的受体。 这些相互作用中的许多相互作用在时间上与通过衣原体III型分泌系统暴露于纳入膜蛋白暴露于宿主细胞细胞质。 控制局部事件的衣原体蛋白质的另一个例子可能包括募集肌动蛋白以促进进入。 III型分泌的蛋白质称为TARP，被易位，酪氨酸磷酸化，而EBS仍是细胞外的。 TARP与衣原体内部化所需的肌动蛋白招募有关。 衣原体篷布和纳入膜蛋白在衣原体发育中至少定义了两个不同的阶段，其中分泌的效应子可能在定义感染结果中起重要作用。 在TARP的情况下，从细胞外EB的质膜上分泌了预先存在的效应蛋白，而包含膜蛋白需要从头合成，并从内部的RBS中分泌。 分泌效应子分子及其功能的识别将继续提供有关衣原体通过成功病原体的许多适应性的见解。 新生的衣原体夹杂物朝着微管的负端迁移，并利用减去端定向的微管运动动力蛋白在MTOC处进行聚集。 这种相互作用导致正常的中心体定位破坏导致中心体数量缺陷。 衣原体夹杂膜与中心体的关联导致中心体分配和/或细胞因子的失败。心粒体上努力缺陷与早期tumer和最具侵略性癌的细胞周期控制的染色体不稳定性和细胞周期控制的丧失有关。 细菌感染可能导致癌症的假说已经持续了一段时间，但是与病毒诱导的癌症不同，特定的癌基因和分子机制尚未明确确定。 衣原体与动力蛋白和中心体的相互作用表明一种机制，通过诱导异常中心体数，衣原体感染可能是导致染色体不稳定性最终导致转化和肿瘤发育的促成因素。 衣原体组蛋白H1样蛋白HC1和HC2通过对DNA结构产生巨大影响，充当衣原体基因表达的全球调节剂。 苏格兰皇家银行与EBS不同，衣原体组蛋白在发育周期后期被转录。 在发育启动时从衣原体染色质中释放组蛋白的机制尚不清楚。 通过利用大肠杆菌中的异源筛查方案，我们确定了两种新型组蛋白活性调节手段。 组蛋白对DNA的亲和力在感染的早期似乎通过在类异丙型生物合成的非甲甲酸途径中的小型代谢物的合成而受到破坏。 在筛选程序的过程中，我们还确定了一个特别抑制HC1翻译的小调节RNA。