Molecular functions of the murine guanylate binding protein (mGBP) 2 in the immune defense against Toxoplasma gondii

鼠鸟苷酸结合蛋白（mGBP）2在弓形虫免疫防御中的分子功能

• 批准号: 233613836
• 负责人: Professor Dr. Klaus Pfeffer
• 金额: --
• 依托单位: Institut für Medizinische Mikrobiologie und Krankenhaushygiene
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2013
• 资助国家: 德国
• 起止时间: 2012-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/233613836?language=en
• 关键词: Molecular; functions; murine; guanylate; binding

Interferon gamma (IFNgamma) is a proinflammatory cytokine which plays a crucial role in the containment and clearance of infections. Patients with genetic defects, murine model systems as well as in vitro experiments have demonstrated that IFNgamma is an essential cytokine for host defense leading to effective control, especially of intracellular pathogens. IFNgamma receptor stimulation results in activation of cells, primarily through a Jak/Stat mediated massive transcriptional response. Prominently, Guanylate-binding proteins (GBPs) belong to a major family of GTPases being abundantly expressed in response to IFNgamma stimulation. GBPs have been shown to be crucial for restriction of the replication of intracellular parasites, i.e. the worldwide distributed Toxoplasma gondii. T. gondii growth restriction is mediated by recruitment of a set of GBPs to the membrane of the parasitophorous vacuole (PV), translocation into the PV space, and, ultimately, the association of GBP molecules with the membrane of the T. gondii parasite. Employing biochemical and imaging (Laser Scanning Microscopy / Multiparameter Fluorescence Image Spectroscopy) techniques it could be demonstrated that murine GBPs (mGBPs) reside in at least two discrete subcellular reservoirs and attack the parasitophorous vacuole membrane (PVM) as orchestrated, supramolecular complexes forming large, densely packed multimers comprising up to several thousand monomers. The dramatic mGBP enrichment results in the loss of PVM integrity, followed by a direct assault of mGBP2 upon the plasma membrane of the parasite. Recently, we could identify novel interaction partners of mGBP2, such as Cytoskeleton associated protein (Ckap4), Annexin A5 (AnxA5), Galectin 9 (Gal9), and Interferon Stimulated Gene 15 (ISG15) which can be detected at the PV of T. gondii. In the upcoming funding period, the intra- and intermolecular preconditions of the PVM and parasite interactions of mGBP2 will be unraveled and the roles and effector functions of Ckap4, Anxa5, Gal9, and ISG15 in toxoplasma infection will be investigated. Furthermore, novel interactions partners of mGBP2 with anti-parasitic activities will be identified. This project will provide vital dynamic and molecular perceptions into cell-autonomous immunity mediated by GBP effector molecules in host defense against important intracellular pathogens.

干扰素γ (IFNgamma) 是一种促炎细胞因子，在遏制和清除感染中发挥着至关重要的作用。具有遗传缺陷的患者、小鼠模型系统以及体外实验均证明，IFNγ是宿主防御的重要细胞因子，可有效控制尤其是细胞内病原体。 IFNγ 受体刺激导致细胞激活，主要是通过 Jak/Stat 介导的大量转录反应。值得注意的是，鸟苷酸结合蛋白 (GBP) 属于 GTP 酶的主要家族，在 IFNγ 刺激下大量表达。 GBP 已被证明对于限制细胞内寄生虫（即世界范围内分布的弓形虫）的复制至关重要。弓形虫生长限制是通过将一组 GBP 招募到寄生液泡 (PV) 膜、易位到 PV 空间以及最终 GBP 分子与弓形虫寄生虫膜结合来介导的。采用生化和成像（激光扫描显微镜/多参数荧光图像光谱）技术，可以证明鼠 GBP (mGBP) 存在于至少两个离散的亚细胞储存库中，并以精心设计的超分子复合物形式攻击寄生液泡膜 (PVM)，形成大型、致密的多聚体，其中包含 单体多达数千个。 mGBP 的显着富集导致 PVM 完整性丧失，随后 mGBP2 直接攻击寄生虫的质膜。最近，我们可以鉴定出 mGBP2 的新相互作用伙伴，例如细胞骨架相关蛋白 (Ckap4)、膜联蛋白 A5 (AnxA5)、半乳糖凝集素 9 (Gal9) 和干扰素刺激基因 15 (ISG15)，这些可以在弓形虫的 PV 处检测到。在即将到来的资助期内，我们将阐明 PVM 的分子内和分子间先决条件以及 mGBP2 的寄生虫相互作用，并研究 Ckap4、Anxa5、Gal9 和 ISG15 在弓形虫感染中的作用和效应功能。此外，还将鉴定 mGBP2 具有抗寄生虫活性的新型相互作用伙伴。该项目将为 GBP 效应分子介导的细胞自主免疫提供重要的动态和分子感知，以防御重要的细胞内病原体。