VERMONT COBRE: PROJECT 4: SUBVERSION OF HOST CELL SIGNALING BY TOXOPLASMA GOUDII

该子项目是利用NIH/NCRR资助的中心赠款提供的资源的许多研究子项目之一。子项目和研究者（PI）可能从另一个NIH来源获得了主要资金，因此可以在其他CRISP条目中表示。所列机构为中心，不一定是研究者所在机构。弓形虫（Toxoplasma gondii）是一种重要的人类和兽医病原体。本文的目的是了解T.弓形虫干扰宿主细胞信号传导并决定寄生虫存活的功能后果。病原体对宿主的入侵通常激活转录因子的NF-kB家族，其在免疫系统的调节中起重要作用并且通常是抵抗感染所需的。最近的研究表明，T.弓形虫不仅不能激活NF-κ B，而且这种寄生虫还能主动抑制这种信号通路，使寄生虫能够侵入细胞而不触发促炎细胞因子诱导。然而，目前还不清楚T。弓形虫抑制NF-κ B和重要的细胞靶点。我们建议当T.弓形虫感染巨噬细胞的特异性T.弓形虫因子与细胞质中的p65 NF-kB蛋白结合，掩盖其核定位信号并阻止其易位到核中。因此，NF-κ B依赖性细胞因子在T.感染的巨噬细胞中的弓形虫受损，结果，体内的适应性免疫应答也受损。在具体目标1中，我们将确定和表征负责抑制NF-κ B信号通路的寄生虫因子。我们将集中在一个锚定含有TgEST 1207539蛋白，其他寄生虫蛋白，可能与p65 NF-κ B相互作用，并产生寄生虫突变体，不能抑制NF-κ B的激活。在具体目标2中，我们将检查T是否失败。弓形虫抑制NF-κ B恢复巨噬细胞在体外产生细胞因子的能力。我们将研究过表达TgEST 1207539蛋白或感染寄生虫突变体的巨噬细胞的细胞因子产生。在具体目标3中，我们将评估T。不能抑制NF-κ B的弓形虫突变体在体内感染中毒性较小。这些研究的结果将有助于确定NF-κ B信号通路在T细胞免疫应答中的功能意义。刚地。这项研究将对这种寄生虫用来操纵宿主细胞信号的分子机制产生新的见解。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The protozoan parasite Toxoplasma gondii is an important human and veterinary pathogen. The objective of this proposal is to understand how T. gondii interferes with host cell signaling and determine the functional consequences for parasite survival. Invasion of a host by a pathogen usually activates the NF-kB family of transcription factors which play an important role in the regulation of the immune system and are frequently required for resistance to infection. Recent studies have shown that invasion of cells by T. gondii not only fails to activate NF-kB, but this parasite actively inhibits this signaling pathway, enabling the parasite to invade cells without triggering proinflammatory cytokine induction. However, it remains unclear how T. gondii inhibits NF-kB and what is the important cellular target. We propose that when T. gondii infect macrophages the presence of a specific T. gondii factor associates with a p65 NF-kB protein in the cytoplasm masking its nuclear localization signals and preventing its translocation into the nucleus. As a result, expression of NF-kB-dependent cytokines in response to T. gondii in infected macrophages is impaired and, as a consequence, the adaptive immune response is also impaired in vivo. In Specific Aim_ 1 we will identify and characterize parasite factors that are responsible for the inhibition of the NF-kB signaling pathway. We will focus on an ankyrin-containing TgEST 1207539 protein, other parasite proteins that may interact with p65 NF-kB, and on generating parasite mutants that fail to inhibit the activation of NF-kB. In Specific Aim 2 we will examine if failure of T. gondii to inhibit NF-kB restores the ability of macrophages to produce cytokines in vitro. We will study cytokine production of macrophages overexpressing the TgEST 1207539 protein or infected with parasite mutants. In Specific Aim 3 we will evaluate if T. gondii mutants that fail to inhibit NF-kB are less virulent in an in vivo infection. The outcome of these studies will be useful to determine the functional significance of the NF-kB signaling pathway for the immune response to T. gondii. This research will yield new insights into the molecular mechanisms that this parasite uses to manipulate the host cell signaling.