Role of Autophagy in Malaria Sporozoite Differentiation

自噬在疟疾子孢子分化中的作用

• 批准号: 8871099
• 负责人: Isabelle Coppens
• 金额: $ 24.3万
• 依托单位: JOHNS HOPKINS UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-04-16 至 2017-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8871099
• 关键词: ATP phosphohydrolase; Abbreviations; Antimalarials; Autophagocytosis; Autophagosome; Biological Assay; Biological Metamorphosis; Biology; Blood; Blood Circulation; Cell membrane; Cells; Clinical; Culicidae; Data; Deposition; Development; Drug Targeting; Electron Microscopy; Endosomes; Environment; Erythrocytes; Eukaryotic Cell; Event; Exocytosis; Genes; Genome; Goals; Golgi Apparatus; Hepatocyte; Human; Hybrids; Immunofluorescence Immunologic; Infection; Intervention; Invaded; Knock-out; Label; Light; Liver; Lysosomes; Malaria; Mediating; Membrane; Metabolism; Microscopic; Modeling; Molecular; Monitor; Morphology; Multivesicular Body; Organelles; Parasites; Parasitic Diseases; Pathology; Pathway interactions; Persons; Plasmodium; Plasmodium berghei; Plastids; Play; Process; Production; Property; Proteins; Publishing; Role; Shapes; Site; Skin; Specificity; Sporozoites; Staging; Structure; Symptoms; System; Techniques; Therapeutic Intervention; Time; Tissues; Ubiquitin; Vacuolar Protein Sorting; Vacuole; Vesicle; Work; base; biological systems; cell motility; circumsporozoite protein; drug development; extracellular; insight; intrahepatic; mortality; new therapeutic target; novel; prophylactic; protein expression; public health relevance; residence; trait; vector mosquito

 DESCRIPTION (provided by applicant): Plasmodium parasites encounter diverse conditions as they cycle between their vertebrate host and the mosquito vector. Adaptation to these distinct environments requires the parasite to drastically change its morphology and metabolism. A key to the parasite's successful intracellular development in the liver is the conversion of the elongated sporozoite to the round trophozoite, a process that prepares the parasite for the replication in hepatocytes. Very little is known about the biological systems involved in this phenotypic transformation. Our published work has outlined that converting sporozoites expel into their environment organelles such as micronemes that are needed for host cell invasion but useless for parasite replication. We found that the ATG8-conjugation system of the parasite's autophagy machinery is upregulated during sporozoite differentiation, suggesting that an autophagy-like process is activated during conversion. Our preliminary data reveal that the parasites sequester micronemes into autophagosomal compartments defined by the presence of parasite ATG8. We provide morphological evidence that PbATG8-labeled structures associate with the Golgi protein PbGRASP and combine with endosomal multivesicular bodies to form PbVPS4- and PbGRASP-positive autophagic compartments, or amphisomes. In eukaryotic cells, GRASP promotes the fusion of amphisomes with the plasma membrane to release the amphisomal content extracellularly. The overall goal of this proposal is to provide a detailed picture of the mechanisms underlying autophagy-related pathways in sporozoites during their conversion into liver forms. Our hypothetical model highlights a cooperation between the endocytic-exocytic and autophagic systems in intrahepatic Plasmodium to promote microneme exocytosis. Specific Aim 1 will obtain a real-time view of autophagosome maturation and itinerary for extracellular microneme disposal. Specific Aim 2 will analyze the phenotypic traits of Plasmodium Atg8 conditional knockout parasites to evaluate the importance of the parasite ATG8-conjugation system for microneme exocytosis. Specific Aim 3 will investigate the contribution of Plasmodium GRASP to the process of secretory autophagy by generating parasites lacking GRASP expression. While the development of new therapeutics targeting the liver stage has the potential to arrest the onset of a malaria infection, extensive efforts must be deployed to better understand the events that take place in the infected liver. The results of the proposed studies are likely to identify unique and essential components of the organelle remodeling pathways that can serve as potent targets for pharmacologic therapy.

 描述（由申请人提供）：疟原虫寄生虫在脊椎动物宿主和蚊子媒介之间循环时会遇到不同的条件，适应这些不同的环境需要寄生虫显着改变其形态和新陈代谢，这是寄生虫在细胞内成功发育的关键。肝脏是细长子孢子向圆形滋养体的转化过程，这一过程为寄生虫在肝细胞中的复制做好准备，而对此所涉及的生物系统知之甚少。我们发表的工作概述了转化子孢子会排出到其环境细胞器中，例如宿主细胞入侵所需但对寄生虫复制无用的微线体，我们发现寄生虫自噬机制的 ATG8 接合系统在子孢子分化过程中被上调。 ，表明在转化过程中激活了类似自噬的过程。我们的初步数据表明，寄生虫将微线体隔离到由寄生虫的存在定义的自噬体区室中。 ATG8。我们提供的形态学证据表明，PbATG8 标记的结构与高尔基体蛋白 PbGRASP 相关，并与内体多泡体结合形成 PbVPS4 和 PbGRASP 阳性自噬区室或两栖体。在真核细胞中，GRASP 促进两栖体与血浆的融合。该提案的总体目标是提供细胞外的详细图片。我们的假设模型强调了肝内疟原虫内吞-胞吐和自噬系统之间的合作，以促进微线体胞吐作用，从而获得自噬体成熟的实时视图。以及细胞外微线体处理的路线 具体目标 2 将分析有条件的疟原虫 Atg8 的表型特征。敲除寄生虫以评估寄生虫 ATG8 结合系统对微线体胞吐作用的重要性。 具体目标 3 将通过产生缺乏 GRASP 表达的寄生虫来研究疟原虫 GRASP 对分泌性自噬过程的贡献，同时开发针对肝脏阶段的新疗法。有可能阻止疟疾感染的发生，必须做出广泛的努力 旨在更好地了解受感染肝脏中发生的事件，拟议研究的结果可能会确定细胞器重塑途径的独特且重要的组成部分，这些组成部分可以作为药物治疗的有效靶点。