Identifying The Machinery That Translocates Toxoplasma Effectors Into The Host Cell

摘要 顶复门属的主要致病种均为胞内真核生物 通常在受感染宿主的寄生泡（PV）内繁殖的寄生虫 细胞这种生态位对寄生虫的生长既提供了机会也提出了挑战 一方面，它们被隔离在一些免疫防御系统之外， 可能会检测到它们的存在，但同时，PV膜（PVM）呈现出 调节宿主功能所必需的蛋白质效应物输出的物理屏障， 寄生虫的优势 顶复门包括许多重要的人类和动物病原体 包括疟原虫属，引起人类疟疾的隐孢子虫 致人衰弱的淋病，和弓形虫，严重的原因 发育中的胎儿和免疫功能低下者的神经系统疾病 通过癌症（例如，淋巴瘤）、移植或感染，如HIV-AIDS。我们 我最近发现弓形虫速殖子有能力戏剧性地 并使用效应子特异性上调人癌基因c-Myc的表达 从密集的颗粒中释放出来，称为GRA 16。利用基因筛选突变体 在c-Myc上调中有缺陷，我们最近也鉴定了 弓形虫GRA 16和其他致密颗粒效应器易位机制 在PVM上。这些新的蛋白质被命名为MYR 1，MYR 2和MYR 3。的 这里提出的工作目标是确定完成或接近完成的 参与效应物在PVM中易位的机制，确定 宿主反应依赖于这种机制，并阐明了 这些效应物在弓形虫发病机制中重要性。我们将通过 使用生物化学和遗传学方法的组合。 通过这项工作，我们将揭开一个重要的和新颖的细胞片， 生物学和确定最终化疗靶向的关键寄生虫成分 以及改善由该寄生虫和相关寄生虫引起的疾病。

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.