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（由应用提供）：疟原虫在脊椎动物宿主和蚊子载体之间循环时会遇到潜水员条件。对这些不同环境的适应需要寄生虫才能大大改变其形态和代谢。寄生虫在肝脏中成功的细胞内发育的关键是，伸长的孢子岩转化为圆形滋养体，该过程为肝细胞复制的寄生虫准备了寄生虫。关于这种表型转化涉及的生物系统知之甚少。我们发表的工作概述了将孢子虫转化为其环境细胞器，例如宿主细胞侵袭所需的微生物，但对寄生虫复制无用。我们发现，寄生虫自噬机械的ATG8结合系统在Sporozoite分化过程中进行了更新，这表明在转换过程中激活了类似自噬的过程。我们的初步数据表明，寄生虫将微生物隔离到由寄生虫ATG8的存在定义的自噬体室中。我们提供了形态学的证据，表明PBATG8标记的结构与高尔基蛋白PBGRASP相关联并与内体多体体相结合，形成PBVPS4-和PBGRASP阳性自噬隔室或两栖体。在真核细胞中，GRASP促进了两性体与质膜的融合，以外释放两栖含量。该提案的总体目的是提供详细的图片，描述了在孢子菌转化为肝脏形式期间自噬相关途径的基础机制。我们的假设模型突出了肝内疟原虫中的内吞肠细胞和自噬系统之间的协调，以促进微神经胞毒性。特定的目标1将获得自噬体成熟和行程的实时视图，以进行细胞外微原则处置。具体目标2将分析条件敲除寄生虫的质子质量型寄生虫的表型性状，以评估寄生虫ATG8-偶联系统对微原质胞吐作用的重要性。特定目标3将通过产生缺乏掌握表达的寄生虫来研究疟原虫掌握对分泌自噬过程的贡献。虽然针对肝脏阶段的新治疗剂的发展有可能阻止疟疾感染的发作，但必须进行广泛的努力 部署以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和必不可少的成分，这些途径可以作为药物治疗的潜在靶标。