Department of Microbiology, Immunology, and Cancer Biology at the Carter Immunology Center, University of Virginia School of Medicine, Charlottesville, VA, USA.
Center for Membrane and Cell Physiology, Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA, USA.
Nat Commun. 2024 Mar 27;15(1):2698. doi: 10.1038/s41467-024-46790-y.
Toxoplasma gondii is an obligate intracellular parasite of rodents and humans. Interferon-inducible guanylate binding proteins (GBPs) are mediators of T. gondii clearance, however, this mechanism is incomplete. Here, using automated spatially targeted optical micro proteomics we demonstrate that inducible nitric oxide synthetase (iNOS) is highly enriched at GBP2 parasitophorous vacuoles (PV) in murine macrophages. iNOS expression in macrophages is necessary to limit T. gondii load in vivo and in vitro. Although iNOS activity is dispensable for GBP2 recruitment and PV membrane ruffling; parasites can replicate, egress and shed GBP2 when iNOS is inhibited. T. gondii clearance by iNOS requires nitric oxide, leading to nitration of the PV and collapse of the intravacuolar network of membranes in a chromosome 3 GBP-dependent manner. We conclude that reactive nitrogen species generated by iNOS cooperate with GBPs to target distinct structures in the PV that are necessary for optimal parasite clearance in macrophages.
刚地弓形虫是一种专性细胞内寄生的啮齿动物和人类寄生虫。干扰素诱导的鸟苷酸结合蛋白（GBPs）是弓形虫清除的介质，但这种机制并不完全。在这里，我们使用自动化空间靶向光学微观蛋白质组学技术，证明诱导型一氧化氮合酶（iNOS）在鼠巨噬细胞中的 GBP2 寄生空泡（PV）中高度富集。巨噬细胞中 iNOS 的表达对于限制体内和体外弓形虫的负荷是必要的。尽管 iNOS 活性对于 GBP2 的募集和 PV 膜皱襞的形成是可有可无的；但是当 iNOS 被抑制时，寄生虫可以复制、出芽和释放 GBP2。iNOS 介导的弓形虫清除需要一氧化氮，导致 PV 的硝化和染色体 3 GBP 依赖性的腔内膜网络的崩溃。我们得出结论，iNOS 产生的活性氮物种与 GBPs 合作，靶向 PV 中的不同结构，这些结构对于巨噬细胞中最佳的寄生虫清除是必要的。
