Host cell membrane perforation during invasion by Toxoplasma gondii

弓形虫入侵过程中宿主细胞膜穿孔

• 批准号: 10587658
• 负责人: GARY E WARD
• 金额: $ 42.53万
• 依托单位: UNIVERSITY OF VERMONT & ST AGRIC COLLEGE
• 依托单位国家: 美国
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-01-03 至 2027-12-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10587658
• 关键词: Acquired Immunodeficiency Syndrome; Acute; Address; Adverse effects; American; Apical; Apicomplexa; Bioinformatics; Biological; Biological Assay; Biological Process; Biology; Calcium; Cell membrane; Cells; Cellular biology; Cryptosporidiosis; Cryptosporidium; Cytosol; Data; Development; Disease; Electric Conductivity; Erythrocytes; Event; Exocytosis; Fetal Development; Fluo 4; Fluorescence Microscopy; Gene Expression; Goals; Immune; Immunocompromised Host; Immunofluorescence Microscopy; Individual; Infection; Injections; Invaded; Knowledge; Life; Life Cycle Stages; Lipid Bilayers; Malaria; Membrane; Methods; Nature; Needles; Organ Transplantation; Organelles; Parasites; Pathogenesis; Pathogenicity; Perforation; Persons; Pharmaceutical Preparations; Plasma Cells; Plasmodium; Play; Population; Process; Protein translocation; Proteins; Role; Speed; Testing; Toxoplasma gondii; Toxoplasmosis; Virulence; Virulence Factors; Visualization; calcium indicator; chemotherapy; cost; drug development; exosome; experience; extracellular; fascinate; genetic approach; human pathogen; improved; novel; novel strategies; novel therapeutic intervention; parasite invasion; patch clamp; prevent; reverse genetics; rhoptry; therapeutic development; virtual

Toxoplasma gondii is a widespread protozoan parasite that can cause life-threatening disease in immunocompromised individuals and the developing fetus. While drugs are available to treat acute toxoplasmosis, they are frequently discontinued due to severe adverse effects. The development of new, better- tolerated drugs requires an improved understanding of the biology of T. gondii and the mechanisms underlying its virulence so that critical points of vulnerability in its life cycle can be identified and targeted. T. gondii belongs to a group of related human pathogens, the Apicomplexa, which also includes the causative agents of malaria (Plasmodium) and cryptosporidiosis (Cryptosporidium). Apicomplexan parasites must invade into cells of their hosts in order to survive and multiply. During the early stages of invasion, proteins are exocytosed from apical organelles known as the rhoptries. After their release, these proteins are delivered into the host cell cytosol where they participate in parasite internalization, inactivate host innate immune defenses, and manipulate host gene expression to the parasite’s advantage. Because the injected effector proteins play such critical roles in parasite invasion and intracellular survival, they are among the most important of the parasite’s virulence factors. While we know a great deal about the functions of these effector proteins, we know virtually nothing about the process by which they are delivered into the host cell. The goal of this project is to fill in this important gap in our understanding of host cell invasion by apicomplexan parasites. We have previously shown that when T. gondii first contacts a host cell, it causes a transient (~200msec) disruption in the barrier integrity of the host cell plasma membrane. The central hypothesis of this project is that this transient perforation of the host cell membrane, which we can detect using high-speed multiwavelength fluorescence microscopy, serves as the conduit through which rhoptry proteins are injected into the host cell. The major Aims of the project are to: (1) Determine the physical nature and proximate cause of host cell perforation during invasion and (2) Determine how the perforating agent is delivered to the host cell membrane and the function of the breach it creates. How rhoptry proteins are injected into the host cell during invasion is a fascinating cell biological problem, and current evidence suggests that the underlying mechanisms are novel. A greater understanding of these mechanisms may lead to new approaches to treating or preventing toxoplasmosis, since targeting the injection process will simultaneously disrupt the delivery into the host cell of many of the parasite’s most critical virulence factors. In addition, because rhoptry protein injection into the host cell occurs in all apicomplexans examined, the results of this project are likely to be directly applicable to related human pathogens such as Plasmodium and Cryptosporidium.

弓形虫Gondii是一种广泛的原生动物寄生虫，可能导致威胁生命的疾病 虽然有药物可用于治疗急性 弓形虫病，由于严重的不良反应，它们经常被停用。新的，更好的发展 耐受性药物需要对T. gondii的生物学和基本机制的生物学有了改进的了解 它的病毒，以便可以识别和瞄准其生命周期中脆弱性的关键点。 T. gondii属于一组相关的人类病原体，即apicomplexa，其中还包括因果关系 疟疾药物（疟原虫）和隐孢子虫病（隐孢子虫）。 Apicomplexan寄生虫必须入侵 进入宿主的细胞，以生存和繁殖。在入侵的早期阶段，蛋白质是 来自称为Rhoptries的顶端细胞器的胞外。发布后，这些蛋白质被输送到 他们参与寄生虫内在化的宿主细胞细胞质，灭活宿主先天免疫防御， 并操纵寄生虫表达寄生虫的优势。因为注射效应蛋白可以发挥 这种关键作用在寄生虫入侵和细胞内存活中，它们是最重要的 寄生虫的病毒因素。尽管我们对这些效应蛋白的功能了解很多，但我们知道 几乎没有关于将它们传递到主机单元的过程。该项目的目的是填补 在我们理解Apicomplexan寄生虫侵袭宿主细胞的这一重要差距中。 我们以前已经表明，当弓形虫首次接触宿主单元时，它会导致瞬态（〜200msec） 宿主细胞质膜的屏障完整性的破坏。该项目的中心假设是 宿主细胞膜的这种短暂穿孔，我们可以使用高速多波长检测到它 荧光显微镜作为导管，将Rhoptry蛋白注入到宿主细胞中。 该项目的主要目的是：（1）确定宿主细胞的物理性质和直接原因 入侵期间的穿孔，（2）确定如何将穿孔剂传递到宿主细胞膜 以及它创造的漏洞的功能。 在入侵期间，如何将Rhoptry蛋白注入宿主细胞是一个引人入胜的细胞生物学问题， 目前的证据表明，潜在机制是新颖的。对这些的更多了解 机制可能导致治疗或预防弓形虫病的新方法，因为针对注射 过程只会简单地破坏寄生虫许多最关键病毒的宿主细胞的传递 因素。另外，由于在检查的所有Apicomplexans中都会注射出宿主细胞中的Rhoptry蛋白，所以 该项目的结果可能直接适用于相关的人病原体，例如疟原虫 和隐孢子虫。