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载体之间循环时遇到不同的条件。为了适应这些不同的环境，寄生虫需要彻底改变其形态和代谢。寄生虫在肝脏中成功细胞内发育的关键是将细长的子孢子转化为圆形滋养体，这是一个准备寄生虫在肝细胞中复制的过程。关于这种表型转化所涉及的生物系统知之甚少。我们已发表的工作概述了转换子孢子排出到它们的环境细胞器，如微线，需要宿主细胞入侵，但无用的寄生虫复制。我们发现，寄生虫的自噬机制的ATG 8共轭系统在子孢子分化过程中上调，这表明自噬样过程在转化过程中被激活。我们的初步数据表明，寄生虫隔离微线体进入自噬体的隔间定义的寄生虫ATG 8的存在。我们提供的形态学证据表明，PbATG 8标记的结构与高尔基体蛋白PbGRASP和联合收割机与内体多泡体形成PbVPS 4和PbGRASP阳性自噬区室，或两性体。在真核细胞中，GRASP促进两性体与质膜的融合以将两性体内容物释放到细胞外。这个建议的总体目标是提供一个详细的图片的机制的自噬相关途径的子孢子在其转换成肝脏的形式。我们的假设模型强调了肝内疟原虫的内吞-外吞和自噬系统之间的合作，以促进微线胞吐。具体目标1将获得自噬体成熟的实时视图和细胞外微线处置的行程。具体目标2将分析疟原虫Atg 8条件敲除寄生虫的表型性状，以评估寄生虫ATG 8缀合系统对微线胞吐的重要性。具体目标3将研究疟原虫GRASP的分泌性自噬过程中产生的寄生虫缺乏GRASP表达的贡献。虽然开发针对肝脏阶段的新疗法有可能阻止疟疾感染的发作，但必须做出广泛的努力， 部署以更好地了解受感染肝脏中发生的事件。拟议的研究结果可能会确定细胞器重塑途径的独特和必要的组成部分，可以作为药物治疗的有效靶点。