Mechanisms of host leukocyte-mediated Toxoplasma dissemination in its host

宿主白细胞介导的弓形虫在宿主体内传播的机制

• 批准号: 10623334
• 负责人: Baoyu Chen
• 金额: $ 46万
• 依托单位: UNIVERSITY OF CALIFORNIA AT DAVIS
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-05-17 至 2027-04-30
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10623334
• 关键词: 2-tyrosine; Acquired Immunodeficiency Syndrome; Actins; Adaptor Signaling Protein; Adhesives; Affect; Animal Model; Animals; Attenuated Vaccines; Bar Codes; Behavior; Binding; Biochemical; Biochemistry; Biological Assay; Bioluminescence; Blindness; Brain; CRISPR/Cas technology; Cell-Matrix Junction; Cells; Cellular biology; Cessation of life; Co-Immunoprecipitations; Complex; Cytoskeleton; Cytosol; Data; Defect; Dendritic Cells; Development; Disease; Disseminated Malignant Neoplasm; Distant; Equus caballus; Exhibits; Fetus; Foundations; Genes; HIV; Human body; Image; Immune; Immune system; Immunocompromised Host; In Vitro; Individual; Infant; Infection; Intervention; Knowledge; Leukocytes; Life; Luciferases; Measures; Mediating; Mesenchymal; Molecular; Mothers; Mus; NCK adaptor protein 1; NR0B2 gene; Names; Organ; PTPN11 gene; PTPN6 gene; Parasites; Pathology; Pathway interactions; Patients; Peptides; Persons; Phosphoric Monoester Hydrolases; Polymers; Population; Process; Proline-Rich Domain; Protein Kinase; Protein Tyrosine Phosphatase; Proteins; Recombinants; Regulation; Research; Route; Shuttle Vectors; Site; Structure; Testing; Therapeutic Intervention; Time; Tissues; Toxoplasma; Toxoplasma gondii; Toxoplasmosis; Transplant Recipients; Tyrosine Phosphorylation; Vaccines; Work; acute infection; cancer cell; cell motility; foodborne; immunosuppressed; in vivo; innovation; insight; loss of function; migration; mutant; novel; novel therapeutics; parasite invasion; pathogen; polymerization; prevent; protein protein interaction; protein purification; receptor; response; rho; transmission process

The intracellular parasite Toxoplasma gondii causes life-threatening disease in immunosuppressed or transplant patients. Its pathology mainly relies on the dissemination of the parasite from the site of infection to various essential organs, such as the brain, where it causes tissue destruction. T. gondii often uses a Trojan Horse mechanism to facilitate its dissemination, during which it hijacks the host cell migration machinery to co- opt host leukocytes as shuttling vectors. Exactly how T. gondii does so, however, is largely unknown. We recently identified a novel T. gondii protein important for its dissemination, which we named TgWIP. We found that upon invasion the parasite secreted TgWIP into the host cell cytosol, where TgWIP stimulated dendritic cells to become hyper-migratory and undergo a mesenchymal to amoeboid transition (MAT). The process was associated with a dramatic rearrangement of the actin cytoskeleton. The overall objective of this application is to determine the molecular mechanisms by which TgWIP mediates T. gondii dissemination in the host. Our central hypothesis is that TgWIP promotes dissemination by modulating leukocyte actin dynamics. This hypothesis was formulated based on our preliminary data showing that TgWIP directly interacts with several central regulators of the actin cytoskeleton involved in cell migration, including the WAVE regulatory complex (WRC), the SH2-SH3 adaptor proteins Nck and Grb2, and the SHP1/2 tyrosine phosphatases. We will test our hypothesis by pursuing two aims: 1) determine how TgWIP interacts with various actin regulators to modulate host actin dynamics in vitro, and 2) determine how TgWIP enhances host leukocyte motility to facilitate dissemination in vivo. Specifically, our team will combine biochemistry, cell biology, and animal models to determine (i) how TgWIP directly interacts with the WRC, Nck, Grb2, and SHP1/2, and how the interactions influence actin polymerization in vitro; (ii) how these interactions alter the migrative behaviors of primary dendritic cells; and (iii) how disruption of these interactions influences in vivo dissemination of T. gondii in mice. Our proposed research is innovative because it will unravel a novel mechanism by which TgWIP, as a newly identified parasite effector unique to T. gondii, coordinates several distinct host actin regulators to reroute leucocyte migration and facilitate T. gondii dissemination. Our work is significant because understanding the molecular and biochemical mechanisms underlying T. gondii dissemination will lay the foundation for the development of novel interventions that can directly target these mechanisms and block T. gondii dissemination after acute infection or reactivation in AIDS or transplant patients or from the mother to the fetus. This knowledge will be also important for the development of a safe, non-transmissible live vaccine that can prevent T. gondii transmission from animals. Furthermore, by understanding how TgWIP promotes MAT in infected DCs, our work will provide valuable insights into how other cells, such as metastatic cancer cells and leukocytes, may use a similar mechanism to undergo MAT in response to diverse environmental conditions.

细胞内寄生虫弓形虫在免疫抑制或 移植病人。其病理主要依赖于寄生虫从感染部位传播到 引起组织破坏的各种重要器官，如大脑。弓形虫经常使用特洛伊木马 马机制，促进其传播，在此期间，它劫持宿主细胞迁移机制，以协同 选择宿主白细胞作为穿梭载体。然而，弓形虫到底是如何做到这一点的，在很大程度上是未知的。我们 最近发现了一种新的弓形虫蛋白，我们将其命名为TgWIP。我们发现 当寄生虫入侵时，TgWIP分泌到宿主细胞胞浆，在那里TgWIP刺激树突状细胞 细胞过度迁移，并经历间充质向阿米巴样转变(MAT)。这一过程是 与肌动蛋白细胞骨架的戏剧性重排有关。这个应用程序的总体目标是 目的：探讨TgWIP介导弓形虫在宿主体内传播的分子机制。我们的 中心假说是TgWIP通过调节白细胞肌动蛋白动力学促进扩散。这 根据我们的初步数据提出了假设，表明TgWIP直接与几个 参与细胞迁移的肌动蛋白细胞骨架的中央调节器，包括WAVE调节复合体 (WRC)，SH2-SH3接头蛋白Nck和Grb2，以及SHP1/2酪氨酸磷酸酶。我们将测试我们的 假说通过追求两个目标：1)确定TgWIP如何与不同的肌动蛋白调节因子相互作用来调节 宿主肌动蛋白的体外动力学，以及2)确定TgWIP如何促进宿主白细胞的运动 在体内传播。具体来说，我们的团队将结合生物化学、细胞生物学和动物模型来 确定(I)TgWIP如何直接与WRC、NCK、Grb2和SHP1/2相互作用，以及如何相互作用 影响肌动蛋白体外聚合；(Ii)这些相互作用如何改变初级肌动蛋白的迁移行为 树突状细胞；以及(Iii)这些相互作用的中断如何影响弓形虫在小鼠体内的传播。 我们提出的研究具有创新性，因为它将揭示一种新的机制，通过它，TgWIP作为一种新的 已识别的弓形虫特有的寄生虫效应器，协调几个不同的宿主肌动蛋白调节因子改变路线 白细胞迁移和促进弓形虫传播。我们的工作意义重大，因为我们理解 弓形虫传播的分子和生化机制将为 开发可直接针对这些机制并阻断弓形虫的新型干预措施 在急性感染或重新激活后在艾滋病或移植患者中或从母亲传给胎儿后传播。 这一知识对于开发一种安全、不可传播的活疫苗也将是重要的，这种疫苗可以 防止弓形虫通过动物传播。此外，通过了解TgWIP如何在 我们的工作将为其他细胞，如转移性癌细胞和 对于不同的环境条件，白细胞可能会使用类似的机制来进行MAT。