The plant-like vacuole of Toxoplasma gondii

弓形虫的植物样液泡

• 批准号: 8258564
• 负责人: Silvia N Moreno
• 金额: $ 37.13万
• 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/8258564
• 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. PUBLIC HEALTH RELEVANCE: This work is designed to test the hypotheses that the plant-like vacuole (PLV) of T. gondii is involved in the regulation of calcium and pH homeostasis and response to salt stress, as well as in sorting and processing of proteins to organelles such as the rhoptries and acidocalcisomes. Our work could provide potential targets for chemotherapy.

描述（由申请人提供）：弓形虫Gondii属于Apicomplexa，是免疫功能低下患者的先天性疾病和感染的重要原因。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。这些分泌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和rhoptries之间的隔室，其中发生了分类和加工。 我们最近发现了一个新型的高尔基菌t. gondii后室，我们将其命名为类似植物的液泡（PLV），该项目的目的是研究其在寄生虫生物学中的功能。该细胞器是一种大型的多动物结构，与植物细胞中的中央液泡具有相似之处。该细胞器可以用与液泡植物泵和通道相似的蛋白质标记，例如K+敏感的V-H+PPase（TGVP1）和托管类样的水aquaporin（TGAQP1）。生理研究进一步揭示了与植物液泡的相似之处，例如存在V-H+ATPase，Na？和Ca2？抗植物和钙存储。此外，作为植物液泡，PLV还含有蛋白酶，例如组织蛋白酶L（TGCPL）等。我们的结果和我们的合作者的结果表明，PLV是细胞外速二核的重要特征，并且由于植物液泡具有多个潜在功能，包括在蛋白质分类和对环境压力的抗性中的作用。例如，该液泡在至少两个微原质前体蛋白（ProtgM2AP和ProtgMIC3）中的作用表明，该细胞器可以代表一个内吞/外胞球群，其中靶向靶向各种细胞器的蛋白质。 PLV中过表达VP1的T. gondii tachyzoites对钠应激更具耐药性，表明PLV在抵抗环境离子应激中的重要作用。离子应力是弓形虫在将宿主细胞退出细胞外培养基时面临的主要挑战。在细胞内和细胞外环境之间，钠，钾，钙和其他离子的浓度发生了巨大变化。处理这些压力变化对于寄生虫的存活很重要，寄生虫需要积极侵入其他宿主细胞继续其裂解周期。 我们将使用遗传和细胞生物学实验的组合来测试两个假设，这些假设是根据植物液泡和寄生虫初步观测的功能进行了开发的。这种新颖的细胞器起作用，可调节离子和/或作为用于微生物，rhoptries和Acidocalcisomes的分泌蛋白的高尔基分类室。如果我们考虑到植物液泡具有复杂功能（存储，排序，压力，植物生长等）的故乡，那么这些模型就不会相互排斥。我们认为，PLV在寄生虫的细胞外相中起着核心作用，不仅在抵抗环境应力方面，而且还为入侵下一个宿主细胞做好准备。 公共卫生相关性：这项工作旨在测试gondii的植物样液泡（PLV）参与钙和pH稳态的调节以及对盐胁迫的反应，以及将蛋白质以及诸如rhoptries和Acid酸性的细胞器的分类和加工对细胞器的分类和加工。我们的工作可以为化学疗法提供潜在的靶标。