Organization of Toxoplasma invasion and cell division by EF-hand proteins

EF-hand 蛋白组织弓形虫入侵和细胞分裂

基本信息

批准号：
8661114
负责人：
Marc-Jan Gubbels
金额：
$ 7.83万
依托单位：
BOSTON COLLEGE
依托单位国家：
美国
项目类别：
财政年份：
2013
资助国家：
美国
起止时间：
2013-05-14 至 2016-04-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8661114
关键词：
Address Affect Affinity Amino Acids Binding Binding Proteins Calcineurin Calmodulin Calmodulin-Binding Proteins Cell Cycle Cell Division Process Cell division Cells Centrosome Complement Complex Congenital Abnormality Contracts Cre-LoxP Cytoskeleton DNA Repair Data Daughter Disease Dissection EF Hand Motifs EF-Hand Domain Encephalitis Essential Genes Event Family Family member Future Gene Family Genes Genome Goals Helix-Loop-Helix Motifs Immune response Immunocompromised Host Infection Ionophores Ions Knock-out Lead Life Life Cycle Stages Lifting Light Lytic Lytic Phase Mammalian Cell Mediating Mitosis Names Nonmuscle Myosin Type IIA Organelles Organism Orthologous Gene Parasites Pathogenesis Pathology Pattern Play Process Protein Dynamics Protein Family Proteins Research Personnel Role Signal Pathway Signal Transduction Pathway Structure Time Tissues Toxoplasma Toxoplasma gondii Translating Trimethoprim-Sulfamethoxazole Work calcineurin phosphatase calcium-dependent protein kinase cell motility extracellular follow-up insight member mutant protein function public health relevance research study segregation

项目摘要

DESCRIPTION (provided by applicant): The apicomplexan parasite Toxoplasma gondii is the causative agent of life-threatening encephalitis in immunocompromised patients and in addition can cause a variety of birth defects if the infection is contracted congenitally. The pathology associated with disease originates in fast rounds of lytic intracellular replication cycles, causin extensive tissue damage. Since parasite replication only occurs within a cell from the mammalian host, the related processes of host cell invasion and egress mark essential steps in the pathogenesis. It has been firmly established that the signaling pathways underlying invasion and egress revolve around the cytoplasmic rise of Ca2+ concentration. Two small, Ca2+-binding proteins, calmodulin (CaM; 4 EF-hands) and the calcineurin phosphatase (the regulatory ¿-subunit has 4 EF hands), have been associated with activation of egress/invasion through pharmacological studies. Furthermore, a related group of small, 4-EF-hand containing proteins consisting of three centrins (Cen1-3) are critical components to the cell division machinery: Cen1 and Cen3 in centrosome duplication, required for mitosis and coordination of the unusual cell division process; Cen2 in contraction of the basal complex required for daughter parasite segregation. In essence, this family of EF-hand proteins plays pivotal roles in the defining steps of pathogenesis: invasion/egress and cell division. However this protein family has never been comprehensively studied, despite their critical roles in pathogenesis. To fill this void, the researchers identified a total of 16 such proteins in the genome, most of which have not been studied at all but likely execute additional functions in these processes. Preliminary sub-cellular localization dynamics of these proteins throughout the lytic cycle support this hypothesis and permits putative assignment to roles in cell division or invasion/egress. It is proposed to complete these preliminary studies for the whole family followed by conditional gene knock-outs of the ten prioritized candidates. To illustrate the power of this approach, these experiments will for the first time directly address whether CaM or calcineurin have a role in egress/invasion, for which only indirect pharmacological data is currently available. Furthermore, using the Cen2 and CaM as a pilot, the direct dissection of the role of Ca2+-binding in the family members with critical roles in invasion or cell division will be pioneered. It is anticipated that these studieswill lift the veil on the enigmatic role of Cen2 in Toxoplasma cell division and/or cytoskeleton structure. In conclusion, this study of a poorly studied gene family is expected to provide key insights into two key aspects in apicomplexan parasite pathogenesis.

描述（由申请人提供）：顶复门寄生虫弓形虫是免疫功能低下患者中危及生命的脑炎的病原体，此外，如果先天性感染，还可导致多种出生缺陷。与疾病相关的病理起源于快速循环。由于寄生虫复制仅发生在哺乳动物宿主细胞内，因此宿主细胞入侵和细胞内复制周期的相关过程会导致广泛的组织损伤。众所周知，侵袭和流出的信号通路围绕着细胞质中 Ca2+ 浓度的升高，即钙调蛋白（CaM；4 EF-hands）和钙调神经磷酸酶。通过药理学研究，磷酸酶（调节 ¿ 亚基有 4 个 EF 手）与流出/入侵的激活有关。 4-EF-hand 含有由三个中心蛋白 (Cen1-3) 组成的蛋白质，是细胞分裂机制的关键组成部分：中心体复制中的 Cen1 和 Cen3，是有丝分裂和协调基底收缩中异常细胞分裂过程所必需的；从本质上讲，这个 EF-hand 蛋白家族在发病机制的决定步骤中发挥着关键作用：入侵/流出和细胞分裂，然而，尽管该蛋白家族发挥了关键作用，但从未得到全面研究。为了填补这一空白，研究人员在基因组中总共鉴定了 16 种此类蛋白质，其中大多数尚未被研究，但可能在这些过程中执行额外的功能。这些蛋白质在整个裂解周期中的定位动态支持了这一假设，并允许假定分配其在细胞分裂或入侵/流出中的作用。建议完成整个家族的这些初步研究，然后对十个优先候选者进行条件基因敲除。为了说明这种方法的威力，这些实验将。首次直接解决 CaM 或钙调磷酸酶是否在流出/侵袭中发挥作用，目前只有间接药理学数据可用。此外，使用 Cen2 和 CaM 作为试点，直接剖析 Ca2+ 结合在中的作用。预计这些研究将揭开 Cen2 在弓形虫细胞分裂和/或细胞骨架结构中神秘作用的面纱。总之，这项对一个研究较少的基因家族的研究预计将为顶复门寄生虫发病机制的两个关键方面提供重要见解。