Identifying The Machinery That Translocates Toxoplasma Effectors Into The Host Cell

摘要 Apicomplexa的主要致病物种都是胞内真核生物 通常在受感染宿主的寄生空泡(PV)内繁殖的寄生虫 细胞。这一利基市场对不断增长的寄生虫来说既是机遇，也是挑战 一方面，它们被隔离在一些免疫防御系统之外， 可以检测到它们的存在，但同时，光伏薄膜(PVM)呈现出 调节寄主功能所需的蛋白质效应物出口的物理障碍 寄生虫的优势。 尖端复合体门包括许多重要的人类和动物病原体 包括人类疟疾的起因疟原虫、微小隐孢子虫、 致衰性腹泻病的病因，以及弓形虫的严重病因 发育中的胎儿和免疫受损的人的神经系统疾病 通过癌症(如淋巴瘤)、移植或感染，如艾滋病毒-艾滋病。我们 最近确定弓形虫速殖子有能力戏剧性地 并利用效应器上调人类癌基因c-Myc的表达 从称为GRA16的致密颗粒中释放出来。利用基因筛查突变者 有缺陷的c-Myc上调，我们最近也发现了第一个组成部分 转运GRA16和其他致密颗粒效应器的弓形虫机械 穿过PVM。这些新蛋白被命名为MYR1、MYR2和MYR3。这个 这里提出的工作目标是确定完成或接近完成的 参与跨PVM的效应器转移的机械，决定 依赖于这一机制的宿主反应，并阐明 这些效应因子在弓形虫发病机制中的重要性。我们会把这件事做完 使用生化和遗传方法的组合。 通过这项工作，我们都将揭开一块重要而新颖的细胞的面纱 生物学和鉴定最终化疗靶向的关键寄生虫成分 以及这种寄生虫和相关寄生虫引起的疾病的改善。

Abstract The major pathogenic species of Apicomplexa are all intracellular eukaryotic parasites that generally reproduce within a parasitophorous vacuole (PV) in infected host cells. This niche presents both an opportunity and a challenge to the parasites growing within – on the one hand, they are sequestered from some of the immune defenses that might detect their presence but at the same time, the PV membrane (PVM) presents a physical barrier to the export of protein effectors necessary to modulate host functions to the parasite's advantage. The phylum Apicomplexa includes many important human and animal pathogens including Plasmodium sp., the cause of human malaria, Cryptosporidium parvum, the cause of debilitating diarrheal disease, and Toxoplasma gondii, the cause of serious neurologic disease in the developing fetus and those who are immunocompromised through cancer (e.g., lymphoma), transplantation or infections, such as HIV-AIDS. We have recently determined that Toxoplasma tachyzoites have the ability to dramatically and specifically up-regulate expression of the human oncogene, c-Myc, using an effector released from dense granules, called GRA16. Using a genetic screen for mutants defective in c-Myc up-regulation, we have also recently identified the first components of the Toxoplasma machinery that translocates GRA16 and other dense granule effectors across the PVM. These novel proteins have been dubbed MYR1, MYR2 and MYR3. The goal of the work proposed here is to identify the complete or near complete machinery involved in translocation of effectors across the PVM, determine the host responses that are dependent on this machinery, and elucidate the importance of these effectors in Toxoplasma pathogenesis. We will do this through using a combination of biochemical and genetic approaches. Through this work, we will both unveil an important and novel piece of cell biology and identify crucial parasite components for eventual chemotherapeutic targeting and amelioration of the disease caused by this and related parasites.