Dissecting the role of Toxoplasma CDPK3 in parasite propagation and virulence

 描述（由申请方提供）：弓形虫是一种专性细胞内寄生虫，已知可慢性感染三分之一的人群。T.弓形虫是一种机会性感染因子，可在艾滋病患者中引起脑炎和其他严重表现。T所需的事件刚地虫的侵入、外出和运动受钙信号传导过程的调节，所述钙信号传导过程包括与人类宿主的蛋白质和因子显著不同的蛋白质和因子。为了利用这些事件作为潜在的药物靶点，需要更好地了解T。弓形虫的钙信号级联。钙依赖性蛋白激酶（CDPKs）的一个特殊家族引起了人们的特别关注，因为它在人类细胞中不存在，并且参与了关键过程。通过正向遗传方法，我们发现TgCDPK 3突变导致钙离子载体诱导的外出（iiEgress）延迟，重要的是小鼠大脑中潜伏期形成的缺陷。利用一种新的蛋白质-蛋白质相互作用的筛选，我们鉴定了几种可能作为蛋白质相互作用的功能伴侣或底物的蛋白质。 TgCDPK 3，包括一个蛋白磷酸酶2C，我们命名为TgPP 2C 4和另一个钙依赖性蛋白激酶TgCDPK 2a。我们假设TgCDPK 3、TgCDPK 2a和TgPP 2C 4形成了寄生虫毒力所必需的“共调节”网络的一部分。我们的第一个目标是分析TgPP 2C 4和TgCDPK 2a的定位和功能。此外，我们将确定这两种酶的底物和功能伙伴，这将使我们能够定义由TgCDPK 3，TgCDPK 2a和TgPP 2C 4共同调控的事件和蛋白质。我们的第二个目标是确定TgCDPK 3在毒力中的作用。这将通过分析缺乏TgCDPK 3或其共调节伴侣TgCDPK 2和TgPP 2C的寄生虫的体内传播和包囊形成来实现。此外，我们将确定TgCDPK 3的底物在包囊化的过程中，在组织培养，这将提供在体内繁殖和发育过程中的TgCDPK 3的功能的机制的见解。结合起来，我们的工作将阐明钙信号在生命周期中的作用 中医弓形虫，并有可能揭示新的目标，以打击急性和慢性弓形虫病。

 DESCRIPTION (provided by applicant): Toxoplasma gondii is an obligate intracellular parasite known to chronically infect a third of the human population. T. gondii is an opportunistic infectious agent that can cause encephalitis and other severe manifestations in AIDS patients. Events required for T. gondii invasion, egress and motility are regulated by calcium signaling processes that include proteins and factors significantly divergent from those of the human host. To exploit these events as potential drug targets would require a better understanding of T. gondii's calcium signaling cascades. A particular family of calcium dependent protein kinases (CDPKs) has garnered special attention, as it is absent from human cells and it is involved in key processes. Through a forward genetic approach we discovered that mutations in TgCDPK3 lead to a delay in calcium ionophore-induced egress (iiEgress), and importantly a defect in the formation of latent stages in the brains of mice. Utilizing a novel screen for protein-protein interactions, we identified several proteins that might act as functional partners or substrates of TgCDPK3, including a protein phosphatase 2C, which we have named TgPP2C4 and another calcium dependent protein kinase TgCDPK2a. It is our hypothesis that TgCDPK3, TgCDPK2a, and TgPP2C4, form part of a "co-regulatory" network essential for parasite virulence. Our first goal will be to analyze the localization and function of both TgPP2C4 and TgCDPK2a. In addition, we will determine the substrates and functional partners of these two enzymes, which will allow us to define the events and proteins co-regulated by TgCDPK3, TgCDPK2a and TgPP2C4. Our second goal will be to determine the role of TgCDPK3 in virulence. This will be accomplished by analyzing the in vivo dissemination and encystation of parasites lacking TgCDPK3 or its co-regulatory partners TgCDPK2 and TgPP2C. Furthermore, we will identify the substrates of TgCDPK3 during the process of encystation in tissue culture, which will provide mechanistic insight into the function of TgCDPK3 during in vivo propagation and development. In conjunction, our work will shed light on the function of calcium signaling during the life cycle of T. gondii and has the potential to reveal novel targets to combat both acute and chronic toxoplasmosis.