Divergent Calcium Channels of the Apicomplexan parasite Toxoplasma gondii

顶复门寄生虫弓形虫的不同钙通道

• 批准号: 10681807
• 负责人: Silvia N Moreno
• 金额: $ 62.48万
• 依托单位: UNIVERSITY OF GEORGIA
• 依托单位国家: 美国
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-02-07 至 2028-01-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10681807
• 关键词: Address; Affinity; Animals; Antiparasitic Agents; Bacteria; Bacterial Adhesins; Biochemical; Biological; Biological Process; Biology; Calcium; Calcium Channel; Calcium Signaling; Candidate Disease Gene; Cell Differentiation process; Cell membrane; Cell physiology; Cells; Characteristics; Clinical; Collaborations; Complex; Cryptosporidiosis; Cytosol; Data; Defect; Dihydropyridines; Disease; Drug Targeting; Electrophysiology (science); Elements; Endoplasmic Reticulum; Environment; Event; Fertilization; Fetus; Gene Expression; Genes; Genetic; Growth; HIV; Image; Immunocompromised Host; Individual; Infection; Invaded; Ion Channel; Ions; Knowledge; Life; Lipid Bilayers; Lytic Phase; Malaria; Mammalian Cell; Modeling; Molecular; Morbidity - disease rate; Muscle Contraction; Names; Neurotransmitters; Nifedipine; Parasites; Parasitology; Pathogenesis; Pathogenicity; Pathology; Pathway interactions; Persons; Physiological; Plants; Play; Population; Proteins; Proteomics; Publishing; Regulation; Research; Role; Rupture; Signal Pathway; Signal Transduction; Source; System; Techniques; Therapeutic; Tissues; Toxoplasma gondii; Toxoplasmosis; Training; Travel; Virulence; Work; cell motility; extracellular; fungus; insight; member; molecular sequence database; mortality; novel; novel therapeutics; opportunistic pathogen; organ transplant recipient; pathogen; receptor; therapeutic target; tool; trait; voltage

PROJECT SUMMARY/ABSTRACT Ca2+ ions impact almost every aspect of cellular life. Ca2+ signaling begins with the opening of Ca2+ channels in either the plasma membrane (PM) or the endoplasmic reticulum (ER) and results in a dramatic increase in the physiologically low (<100 nM) cytosolic Ca2+ levels. The temporal and spatial Ca2+ levels are exquisitely regulated and enable the precise and specific activation of critical biological processes like changes in gene expression, cell differentiation, muscle contraction, fertilization, or secretion of neurotransmitters to name a few. Ca2+ signaling regulates pathogenic pathways of apicomplexan parasites like Toxoplasma gondii which infects approximately one third of the world’s population. T. gondii is an opportunistic pathogen of immunocompromised patients like HIV-infected individuals, fetuses, and organ transplant recipients. As an obligate intracellular pathogen, T. gondii replicates inside cells and the clinical manifestations of toxoplasmosis are a direct result of its growth within cells and its dissemination. T. gondii relies on Ca2+ signals for the stimulation of specific features of its infection cycle and several Ca2+ signaling elements play essential roles in its parasitic cycle. However, the fundamental elements that initiate Ca2+ signals in T. gondii are largely unknown yet are likely essential for its viability and virulence. Discovery and characterization of the molecules that initiate Ca2+ signaling in T. gondii are hence central for the understanding of its pathogenesis. Active egress of T. gondii from host cells is critical for dissemination of the infection and our prior work has provided conclusive evidence that there is a cytosolic Ca2+ peak preceding egress. This parasitic cytosolic increase arises from release from intracellular stores, likely the endoplasmic reticulum. It is puzzling, however, that intracellular parasites replicate surrounded by the low host cytosolic Ca2+ but still store sufficient Ca2+ in their ER to trigger egress. Upon host cell rupture, extracellular Ca2+ influx across the PM contributes to a second Ca2+ peak enhancing motility of parasites, which then exit and seek another host cell to invade. Our hypothesis is that PM Ca2+ entry is essential for refilling of intracellular Ca2+ stores, and both intra and extracellular sources are necessary for triggering the cascade of molecular events that lead to the stimulation of parasitic functions like motility, secretion of adhesins, invasion of host cells, egress and dissemination. In this proposal we aim to characterize the proteins that enable PM Ca2+ influx. There is almost no information about the functional characteristics and roles of Ca2+ channels in T. gondii. This lack of knowledge could be due to lack of appropriate tools, techniques, and training in electrophysiology within the molecular parasitology field. We address this void with a collaboration with a mammalian electrophysiologist and a modeler. Channels are critical for the successful unicellular life of parasites, and they could be targeted by many therapeutically useful agents. Ion channels remain significantly under-exploited as therapeutic targets, even more so as antiparasitic agents.

项目摘要/摘要 Ca2+离子几乎影响细胞寿命的各个方面。 CA2+信号传导始于CA2+通道的打开 在质膜（PM）或内质网（ER）中，导致急剧增加 物理低（<100 nm）的胞质Ca2+水平。临时和空间Ca2+水平完全是 调节并启用关键生物学过程（例如基因变化）的精确和特定激活 表达，细胞分化，肌肉收缩，施肥或神经递质的分泌以命名 很少。 Ca2+信号传导调节Apicomplexan寄生虫的致病途径，例如Toxoplasma gondii 感染了世界人口的大约三分之一。 T. gondii是一种机会性病原体 免疫功能低下的患者，例如HIV感染的个体，胎儿和器官移植受者。作为 强制性细胞内病原体，T。Gondii在细胞内部复制和临床表现。 弓形虫病是其在细胞内生长及其传播的直接结果。 T. gondii依赖Ca2+信号 为了刺激其感染周期的特定特征和几个Ca2+信号传导元素的作用必不可少 在其寄生周期中的作用。但是，在T. gondii中启动Ca2+信号的基本要素在很大程度上是 未知的可能对其生存能力和病毒至关重要。分子的发现和表征 因此，gondii中的Ca2+信号传导是理解其发病机理的中心。活动出口 来自宿主细胞的gondii的T. gondii对于传播感染至关重要，我们先前的工作已提供 结论性证据表明，出口前有胞质Ca2+峰值。这种寄生胞质增加 来自细胞内存储的释放，可能是内质网。但是，难题是 细胞内寄生虫通过低宿主的胞质Ca2+复制，但仍将足够的Ca2+存储在其中 ER触发出口。宿主细胞破裂后，PM的细胞外Ca2+影响有助于第二 CA2+峰值增强的寄生虫运动能力，然后退出并寻求另一个宿主细胞入侵。我们的假设 PM Ca2+进入对于补充细胞内Ca2+存储以及细胞内和细胞外源至关重要 对于触发导致寄生函数刺激的分子事件的级联对于触发级联反应所必需的必要 像运动性，依从性的分泌，侵入宿主细胞，出口和传播一样。在这个建议中，我们的目标是 表征启用PM Ca2+影响的蛋白质。几乎没有有关功能的信息 Ca2+通道在T. gondii中的特征和作用。缺乏知识可能是由于缺乏适当的 分子寄生虫学领域内电生理学的工具，技术和培训。我们解决这个问题 与哺乳动物电生理学家和建模者合作无效。渠道对于 寄生虫的成功单细胞寿命，它们可能是许多治疗用药物的目标。离子 作为治疗靶标的通道仍然显着探索，甚至是抗寄生虫。