The plant-like vacuole of Toxoplasma gondii

弓形虫的植物样液泡

• 批准号: 8385516
• 负责人: Silvia N Moreno
• 金额: $ 34.9万
• 依托单位: UNIVERSITY OF GEORGIA
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-12-01 至 2016-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8385516
• 关键词: Accounting; Adaptor Signaling Protein; Antibodies; Apicomplexa; Biogenesis; Biological; Biology; Calcium; Cathepsin L; Cells; Complex; Defect; Disease; Dominant-Negative Mutation; Environment; Enzymes; Funding; Genetic; Goals; Golgi Apparatus; Grant; Home environment; Homeostasis; Immunocompromised Host; Infection; Invaded; Ions; Label; Lytic Phase; Modeling; Names; Organelles; Parasites; Peptide Hydrolases; Phase; Physiological; Plants; Play; Potassium; Process; Protein Precursors; Proteins; Proton-Translocating ATPases; Protons; Pump; Regulation; Resistance; Role; Route; Sodium; Sodium Chloride; Sorting - Cell Movement; Stress; Structure; System; Testing; Toxoplasma gondii; Transmembrane Transport; Vacuole; Virulence; Work; antiporter; base; chemotherapy; coping; design; extracellular; insight; knockout gene; mutant; novel; overexpression; pH Homeostasis; parasite invasion; plant growth/development; proton-translocating pyrophosphatase; pyrophosphatase; research study; response; rhoptry; secretory protein; trafficking; water channel

DESCRIPTION (provided by applicant): Toxoplasma gondii belongs to the phylum Apicomplexa and is an important cause of congenital disease and infection in immunocompromised patients. The parasite has a complex secretory system essential for host cell invasion and establishment of the parasitophorous vacuole. Biogenesis of these secretory organeles remains poorly understood but several groups have postulated a compartment situated between Golgi and mature micronemes and rhoptries in which sorting and processing occurs. We have recently discovered a novel post-Golgi compartment of T. gondii that we named the plant-like vacuole (PLV) and the goal of this project is to investigate its function in the biology of the parasite. This organelle is a large multi-vesicular structure that possesses similarities to the central vacuole found in plant cells. This organelle can be labeled with antibodies against proteins with great similarity to vacuolar plant pumps and channels, such as a K+sensitive V-H+PPase (TgVP1), and a tonoplast-like aquaporin (TgAQP1). Physiological studies further revealed similarities to plant vacuoles such as the presence of a V-H+ATPase, Na? and Ca2? antiporters, and calcium storage. Furthermore, as plant vacuoles, the PLV also contains proteases such as cathepsin L (TgCPL) and others. Our results and those of our collaborators showed that the PLV is a prominent feature of extracellular tachyzoites and, as the plant vacuole, has multiple potential functions including roles in protein sorting and resistance to environmental stresses. For example, the role of this vacuole in the proteolytic maturation of at least two microneme precursor proteins, proTgM2AP and proTgMIC3, suggests that this organelle could represent an endocytic/exocytic hub where sorting of proteins targeted to various organelles occurs. T. gondii tachyzoites that overexpress VP1 in the PLV, become more resistant to sodium stress pointing to an important role of the PLV in resistance to environmental ionic stress. Ionic stress is a major challenge that T. gondii confronts when exiting the host cell into the extracellular media. There is a dramatic change in the concentration of sodium, potassium, calcium and other ions between the intracellular and the extracellular environment. Dealing with these stressful changes is important for the survival of the parasite, which needs to actively invade other host cells to continue with its lytic cycle. We will test two hypotheses, which have been developed based on the functions of the plant vacuole and preliminary observations in the parasite, using a combination of genetic and cell biological experiments. This novel organelle acts to regulate ions and/or as a post Golgi sorting compartment for secretory proteins destined to the micronemes, rhoptries, and acidocalcisomes. These models are not mutually exclusive if we take into account the fact that the plant vacuole is home to a complex set of functions (storage, sorting, stress, plant growth, etc.). We think that the PLV plays a central role during the extracellular phase of the parasite not only in resisting environmental stress but also as it prepares itself for invading the next host cell.

描述（由申请方提供）：弓形虫属于顶复门，是免疫功能低下患者先天性疾病和感染的重要原因。该寄生虫有一个复杂的分泌系统，对宿主细胞的入侵和寄生空泡的建立至关重要。这些分泌细胞器的生物发生仍然知之甚少，但有几个小组已经假设了一个位于高尔基体和成熟的微丝和棒状体之间的隔间，其中发生分选和加工。 我们最近发现了一个新的T.我们将其命名为植物样空泡（PLV），本项目的目的是研究其在寄生虫生物学中的功能。这种细胞器是一个大的多囊泡结构，与植物细胞中的中央液泡相似。该细胞器可以用针对与液泡植物泵和通道非常相似的蛋白质的抗体标记，例如K+敏感性V-H+PPase（TgVP 1）和液泡膜样水通道蛋白（TgAQP 1）。生理研究进一步揭示了植物液泡的相似性，如存在的V-H+ ATP酶，Na？Ca2？反向转运蛋白和钙储存。此外，作为植物液泡，PLV还含有蛋白酶如组织蛋白酶L（TgCPL）等。我们的研究结果和我们的合作者的研究结果表明，PLV是一个突出的特征，细胞外速殖子，作为植物液泡，具有多种潜在的功能，包括蛋白质分选和抵抗环境胁迫的作用。例如，该液泡在至少两种微线体前体蛋白proTgM 2AP和proTgMIC 3的蛋白水解成熟中的作用表明，该细胞器可能代表内吞/外吞枢纽，其中发生靶向各种细胞器的蛋白质的分选。T.在PLV中过表达VP 1的弓形虫速殖子变得对钠胁迫更具抗性，这表明PLV在抵抗环境离子胁迫中起重要作用。离子应激是T.当弓形虫离开宿主细胞进入细胞外介质时，在细胞内和细胞外环境之间，钠、钾、钙和其他离子的浓度有显著变化。处理这些压力变化对寄生虫的生存很重要，寄生虫需要积极入侵其他宿主细胞以继续其裂解周期。 我们将测试两个假设，这已经开发的基础上的植物液泡的功能和寄生虫的初步观察，使用遗传和细胞生物学实验相结合。这种新的细胞器的作用，以调节离子和/或作为后高尔基体分选室的分泌蛋白注定的微线体，棒状体，和acidocalcisomes。如果我们考虑到植物液泡是一组复杂功能（储存，分选，胁迫，植物生长等）的家，这些模型并不相互排斥。我们认为PLV在寄生虫的细胞外阶段不仅在抵抗环境压力方面发挥着核心作用，而且还为入侵下一个宿主细胞做好准备。