Department of Pathology and Immunology, Washington University School of Medicine in St. Louis, St. Louis, MO 63110;
Department of Pathology and Immunology, Washington University School of Medicine in St. Louis, St. Louis, MO 63110.
Proc Natl Acad Sci U S A. 2021 Jan 5;118(1). doi: 10.1073/pnas.2011763118.
Macrophages activated with interferon-γ (IFN-γ) in combination with other proinflammatory stimuli, such as lipopolysaccharide or tumor necrosis factor-α (TNF-α), respond with transcriptional and cellular changes that enhance clearance of intracellular pathogens at the risk of damaging tissues. IFN-γ effects must therefore be carefully balanced with inhibitory mechanisms to prevent immunopathology. We performed a genome-wide CRISPR knockout screen in a macrophage cell line to identify negative regulators of IFN-γ responses. We discovered an unexpected role of the ubiquitin-fold modifier (Ufm1) conjugation system (herein UFMylation) in inhibiting responses to IFN-γ and lipopolysaccharide. Enhanced IFN-γ activation in UFMylation-deficient cells resulted in increased transcriptional responses to IFN-γ in a manner dependent on endoplasmic reticulum stress responses involving Ern1 and Xbp1. Furthermore, UFMylation in myeloid cells is required for resistance to influenza infection in mice, indicating that this pathway modulates in vivo responses to infection. These findings provide a genetic roadmap for the regulation of responses to a key mediator of cellular immunity and identify a molecular link between the UFMylation pathway and immune responses.
干扰素-γ（IFN-γ）与其他促炎刺激物（如脂多糖或肿瘤坏死因子-α（TNF-α））联合激活的巨噬细胞会发生转录和细胞变化，从而增强清除细胞内病原体的能力，但这也会增加组织损伤的风险。因此，IFN-γ 效应必须与抑制机制相平衡，以防止免疫病理学。我们在巨噬细胞系中进行了全基因组 CRISPR 敲除筛选，以鉴定 IFN-γ 反应的负调节因子。我们发现泛素样修饰（Ufm1）缀合系统（下文称为 Ufmylation）在抑制 IFN-γ 和脂多糖反应方面具有意想不到的作用。Ufmylation 缺陷细胞中 IFN-γ 的激活增强导致 IFN-γ 诱导的转录反应增加，这种方式依赖于涉及 Ern1 和 Xbp1 的内质网应激反应。此外，髓系细胞中的 Ufmylation 对于抵抗小鼠流感感染是必需的，表明该途径调节体内对感染的反应。这些发现为细胞免疫关键介质反应的调节提供了遗传路线图，并确定了 Ufmylation 途径与免疫反应之间的分子联系。
