Elucidating the role of the Toxoplasma residual body in cytoskeleton turnover

阐明弓形虫残体在细胞骨架更新中的作用

• 批准号: 10591825
• 负责人: Michael Lloyd Reese
• 金额: $ 28.7万
• 依托单位: UT SOUTHWESTERN MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-11-04 至 2024-10-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10591825
• 关键词: Actins; Address; Animals; Apical; Auxins; Biochemical; Biochemistry; Biology; Biophysics; Biotinylation; Cell Cycle; Cell membrane; Cell physiology; Cells; Complement; Complex; Complication; Coupled; Cryptosporidiosis; Cytokinesis; Cytoplasm; Cytoskeleton; Data; Daughter; Dependence; Disease; Enzymes; Fluorescence Microscopy; Foundations; Future; Garbage; Giant Cells; Goals; Growth; Human; Immunocompromised Host; In Vitro; Infection; Invaded; Knock-out; Length; Life; Lytic Phase; Malaria; Mass Spectrum Analysis; Mediating; Microtubules; Modeling; Mothers; Names; Organelles; Parasites; Pathogenesis; Phenotype; Planet Earth; Population; Protein Region; Proteins; Reaction; Recombinants; Research; Residual state; Ring Finger Domain; Role; Signal Transduction; Stimulus; Structure; Testing; Toxoplasma; Toxoplasma gondii; Toxoplasmosis; Ubiquitination; Vacuole; cell type; cost; daughter cell; experimental study; fitness; human disease; immunosuppressed; innovation; live cell imaging; loss of function; model organism; multicatalytic endopeptidase complex; mutant; pathogen; premature; prevent; programs; protein degradation; reconstitution; response; targeted treatment; tool; ubiquitin ligase; ubiquitin-protein ligase; virtual

PROJECT SUMMARY/ABSTRACT Toxoplasma gondii has the remarkable ability to infect virtually any cell type of almost all warm-blooded animals and is arguably the most successful parasite on earth, having infected an estimated one-third of humans globally. While initial infection typically resolves without complication, the parasite is able to persist for the life of its host, and can re-emerge in the immunocompromised and immunosuppressed to cause fatal disease. Toxoplasma, like other apicomplexan parasites, has an unusual cell cycle in which daughter cells are fully assembled within a mother before cytokinesis. Because of its unusual features and regulatory checkpoints distinct from mammalian hosts, the parasite cell cycle is an ideal target for therapy In the final steps of Toxoplasma division, the mother cell organelles and cytoskeleton are degraded to make room for the daughter cells. Because the daughter cells must insert their own cytoskeleton, including the host cell invasion machinery, into the plasma membrane, this is a critical point in parasite assembly. Once divided, the daughter cells remain connected through a poorly understood organelle called the residual body. While the residual body was first described over 60 years ago, little is know about it. We have found that maternal cytoskeleton is actively stripped from the plasma membrane and delivered to the residual body, where it is then degraded. We have identified a ubiquitin E3 ligase that localizes to the residual body, and is essential to the turnover of maternal cytoskeleton. Moreover, we have shown that mistargeting of the E3 outside of the residual body results in premature degradation of the daughter cells' invasion machinery, blocking the infective cycle. We have therefore identified the sequestration of protein turnover as a major cellular function for the residual body. The goal of the proposed studies is to (i) understand the functional role of the residual body in Toxoplasma cytokinesis and the turnover of maternal materials, and (ii) to delineate the components of the ubiquitination cascade that targets the parasite cytoskeleton. We will determine what other organelles and structures are delivered to the residual body for turnover and identify the proteins that sequester E3 ligase activity and cytoskeleton degradation within the residual body. Furthermore, we will build the components required for the creation of an innovative reconstitution of the E3 ligase activity that will enable future studies towards generating a mechanistic model of maternal cytoskeleton turnover.

项目总结/摘要 刚地弓形虫具有显著的感染几乎所有温血动物的任何细胞类型的能力， 动物，可以说是地球上最成功的寄生虫，感染了估计三分之一的 全球人类。虽然最初的感染通常没有并发症解决，寄生虫能够持续存在 它的宿主的生命，并可以重新出现在免疫功能低下和免疫抑制，造成致命的 疾病弓形虫，像其他顶复门寄生虫一样，有一个不寻常的细胞周期， 在胞质分裂之前在母体内完全组装。由于其不寻常的特点和监管 与哺乳动物宿主不同，寄生虫细胞周期是治疗的理想靶点 在弓形虫分裂的最后阶段，母细胞的细胞器和细胞骨架被降解， 为子细胞腾出空间。因为子细胞必须插入它们自己的细胞骨架， 宿主细胞的入侵机器进入质膜，这是寄生虫组装的关键点。 一旦分裂，子细胞通过一种鲜为人知的细胞器保持连接，这种细胞器被称为 残留的尸体虽然60多年前第一次描述了残留的尸体，但对它知之甚少。 发现母体细胞骨架被主动地从质膜上剥离，并被运送到 残留的身体，然后在那里降解。我们已经鉴定了一种泛素E3连接酶，其定位于 残留的身体，是必不可少的母亲细胞骨架的周转。此外，我们已经证明， E3在残留体外的错误启动导致子细胞的过早降解， 入侵机器，阻断传染循环。因此，我们确定了蛋白质的螯合作用， 周转作为残留体的主要细胞功能。 拟议研究的目标是：（一）了解残留体的功能作用， 弓形虫胞质分裂和母体物质的周转，和（ii）描绘的组成部分， 靶向寄生虫细胞骨架的泛素化级联。我们将确定其他细胞器和 结构被传递到残余体进行周转，并鉴定螯合E3连接酶的蛋白质 活性和细胞骨架降解的残余体内。此外，我们将构建组件 所需的创造一个创新的重建E3连接酶的活动，这将使未来 研究，以产生一个机制模型的母体细胞骨架营业额。