A novel vacuolar compartment in Toxoplasma gondii

弓形虫中的一种新型液泡室

• 批准号: 7897817
• 负责人: Silvia N Moreno
• 金额: $ 18.56万
• 依托单位: UNIVERSITY OF GEORGIA
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-07-23 至 2012-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7897817
• 关键词: AQP1 gene; Abbreviations; Acquired Immunodeficiency Syndrome; Adaptor Protein Complex 1; Adaptor Protein Complex 3; Adaptor Protein Complex Subunits; Adaptor Signaling Protein; Amino Acids; Biogenesis; Categories; Cathepsin L; Cells; Complex; Diphosphates; Disease; Endosomes; Energy-Filtering Transmission Electron Microscopy; Fetus; Food; Future; Goals; Golgi Apparatus; Human; Immune response; Immunocompetent; Immunocompromised Host; Immunoelectron Microscopy; Immunofluorescence Immunologic; Individual; Infection; Infection Control; Label; Link; Lytic Phase; Metabolic Pathway; Mothers; Mutagenesis; Mutate; Names; Organelles; Osmoregulation; Parasites; Pathology; Pathway interactions; Patients; Personal Communication; Physiological; Pilot Projects; Plants; Polyphosphates; Process; Property; Protein Overexpression; Proteins; Proton Pump; Protons; Reagent; Role; Route; Signal Transduction; Sorting - Cell Movement; System; Testing; Toxoplasma gondii; Toxoplasmosis; Transmission Electron Microscopy; Trypanosoma cruzi; Tyrosine; United States National Institutes of Health; Vacuole; Water; Work; chemotherapy; design; mutant; novel; overexpression; pH Homeostasis; parasite invasion; pathogen; protein transport; proton-translocating pyrophosphatase; public health relevance; pyrophosphatase; research study; rhoptry; stem; trafficking; trans-Golgi Network; water channel; AQP1 gene; Abbreviations; Acquired Immunodeficiency Syndrome; Adaptor Protein Complex 1; Adaptor Protein Complex 3; Adaptor Protein Complex Subunits; Adaptor Signaling Protein; Amino Acids; Biogenesis; Categories; Cathepsin L; Cells; Complex; Diphosphates; Disease; Endosomes; Energy-Filtering Transmission Electron Microscopy; Fetus; Food; Future; Goals; Golgi Apparatus; Human; Immune response; Immunocompetent; Immunocompromised Host; Immunoelectron Microscopy; Immunofluorescence Immunologic; Individual; Infection; Infection Control; Label; Link; Lytic Phase; Metabolic Pathway; Mothers; Mutagenesis; Mutate; Names; Organelles; Osmoregulation; Parasites; Pathology; Pathway interactions; Patients; Personal Communication; Physiological; Pilot Projects; Plants; Polyphosphates; Process; Property; Protein Overexpression; Proteins; Proton Pump; Protons; Reagent; Role; Route; Signal Transduction; Sorting - Cell Movement; System; Testing; Toxoplasma gondii; Toxoplasmosis; Transmission Electron Microscopy; Trypanosoma cruzi; Tyrosine; United States National Institutes of Health; Vacuole; Water; Work; chemotherapy; design; mutant; novel; overexpression; pH Homeostasis; parasite invasion; pathogen; protein transport; proton-translocating pyrophosphatase; public health relevance; pyrophosphatase; research study; rhoptry; stem; trafficking; trans-Golgi Network; water channel

DESCRIPTION (provided by applicant): The pathology associated with toxoplasmosis stems from the parasite's lytic cycle initiated by active invasion of host cells. The parasite has a complex secretory system essential for host cell invasion and establishment of the parasitophorous vacuole. Biogenesis of these organelles remains poorly understood but several groups have postulated a compartment situated between Golgi and mature micronemes or rhoptries in which sorting and processing occurs. We have identified a new compartment and named it multivesicular endosome (MVE) and in this proposal we will test the hypothesis that this compartment represents the endocytic/exocytotic hub where sorting of proteins targeted to various organelles occurs. We will also test the hypothesis that this MVE present in T. gondii tachyzoites, is linked to the acidocalcisomes since both share a similar proton pump (vacuolar proton pyrophosphatase or VP1) and appear to interact. We know that it is also involved in the microneme pathway, as supported by experiments showing that microneme 2 associated protein (M2AP) traverses this compartment en route to the micronemes. The localization of a cathepsin L (CPL) in this compartment supports its postulated role in processing of M2AP. We also hypothesize that this vacuole is the same or is closely related to the multivesicular endosomal compartment that was shown to accumulate rhoptry protein 2 (ROP2) when its dileucine motifs were mutated to dialanine or when the amino acid residues of the 51 subunit of adaptor protein 1 (AP-1) involved in their recognition, were altered by mutagenesis. This compartment could not be identified before because of lack of adequate markers. In addition to VP1, the MVE possesses a water channel or aquaporin (AQP), a property that it shares with the plant cell vacuole and the contractile vacuole and acidocalcisomes of Trypanosoma cruzi. Our hypotheses are that: (1) the T. gondii MVE belongs to the endosomal system and is an intermediate compartment in the trafficking of proteins from the Golgi complex to acidocalcisomes, and secretory organelles; and (2) the T. gondii multivesicular endosome is involved in cellular homeostatic processes. Our specific aims are: (1) Characterize the T. gondii MVE as a trafficking organelle and (2) To study the role of the T. gondii MVE in osmoregulation and intracellular pH homeostasis. These pilot studies will characterize a new parasite compartment of potential great importance to the parasite invasion and host- subversion process. We will develop robust markers, and generate the reagents necessary for future in depth study aimed at a detailed characterization of the trafficking pathway to other secretory organelles and at understanding the physiological roles of the MVE. xoplasma gondii is a pathogenic protozoan parasite infecting a wide range of vertebrate hosts including humans. In immunocompetent individuals, infection is largely asymptomatic and is controlled by the host's immune response. However, T. gondii has also been recognized as a major opportunistic pathogen of fetuses from recently infected mothers and of immunocompromised patients, i.e. those with AIDS. T. gondii can be transmitted through contaminated food and/or water and because of this, it has been listed by NIH as category B priority pathogen. Our studies on characterization of a novel organelle and the study of trafficking of proteins to acidocalcisomes could reveal novel targets for the chemotherapy of toxoplasmosis. PUBLIC HEALTH RELEVANCE: Our goal is to find ways of interfering with Toxoplasma gondii metabolic pathways as a strategy for controlling infections caused by this and similar parasites. Differences in endocytic traffic between T. gondii and its mammalian host could be exploited for chemotherapeutic purposes. This work is designed to test the hypothesis that a multivesicular endosome present in these parasites is involved in trafficking of proteins to acidocalcisomes, and has a role in osmoregulation and intracellular pH homeostasis.

描述（由申请人提供）：与弓形虫病相关的病理源于寄生虫的裂解周期，该裂解周期是由主动侵袭宿主细胞引发的。该寄生虫具有一个复杂的分泌系统，对于宿主细胞侵袭和寄生虫液泡的建立至关重要。这些细胞器的生物发生知之甚少，但有几个组假定位于高尔基体和成熟的微生物或rhoptries之间的隔室，其中进行了分类和加工。我们已经确定了一个新的隔室，并将其命名为多重内体（MVE），在此提案中，我们将测试以下假设：该室代表内吞/胞胞胞菌枢纽，其中靶向各种细胞器的蛋白质分类。我们还将检验以下假设：由于两者都共享相似的质子泵（液泡质子pyrophophatase或vp1），并且似乎相互作用，并且似乎相互作用，因此与酸环异构体相关的该假设与酸环异构体有关。我们知道，它也参与了微神经途径，这表明MicroNeme 2相关蛋白（M2AP）在通往微元素的途径中横穿该隔室。组织蛋白酶L（CPL）在该隔室中的定位支持其在M2AP处理中的作用。我们还假设，当将其Dilecine序列突变为Dileanine或当其识别蛋白1（AP-1）的51个亚基（AP-1）的51个亚基的氨基酸残基突变时，这种真空吸尘器与多个内体内体隔室相同或密切相关。由于缺乏足够的标记，因此无法识别该隔室。除了VP1外，MVE还具有与植物细胞液泡共享的水道或水通道蛋白（AQP），以及Cruzi锥虫的收缩液泡和酸离子。我们的假设是：（1）T。gondii mve属于内体系统，并且是从高尔基体复合物到酸离子到酸离子的蛋白质中的一个中间室，以及分泌的细胞器； （2）T。gondii多尖内体参与细胞稳态过程。我们的具体目的是：（1）将T. gondii mve的特征描述为贩运细胞器，以及（2）研究gondii mve在渗透调节和细胞内pH稳态中的作用。这些试点研究将表征一个对寄生虫入侵和宿主颠覆过程的潜在重要性的新寄生虫区。我们将开发可靠的标记，并生成未来深入研究所需的试剂，以详细描述到其他分泌细胞器的贩运途径，并了解MVE的生理作用。 Xoplasma gondii是一种致病的原生动物寄生虫，感染包括人类在内的广泛的脊椎动物宿主。在免疫能力的个体中，感染在很大程度上是无症状的，并由宿主的免疫反应控制。然而，贡迪链球菌也被认为是最近感染的母亲和免疫功能低下的患者（即患有艾滋病患者）的主要机会病原体。 T. gondii可以通过污染的食物和/或水传播，因此，NIH已将其列为B类优先病原体。我们关于新型细胞器的表征的研究以及蛋白质对酸环异构体的运输的研究可能揭示了弓形虫病化学疗法的新靶标。公共卫生相关性：我们的目标是找到干扰弓形虫代谢途径的方法，以此作为控制由这种和类似寄生虫引起的感染的策略。可以为化学治疗目的而利用T. gondii及其哺乳动物宿主之间内吞交通的差异。这项工作旨在检验以下假设：这些寄生虫中存在的多尖内体参与将蛋白质运输到酸环异构体中，并且在渗透调节和细胞内pH稳态中起作用。