Widespread IFN-independent activities of mammalian STING in viral infection and tumor immune evasion. Widespread IFN-independent activities of mammalian STING in viral infection and tumor immune evasion

Type I interferon (IFN) response is the most recognized signaling activity of STING, and IFN signaling is commonly believed to be the major (if not the sole) contributor to STING-mediated anti-viral and anti-cancer responses. Here, we genetically mutated mouse Sting serine 365 residue that is critically required for initiating IFN signaling. Sting-S365A mutation in mice precisely ablated IFN-dependent while preserving IFN-independent activities of STING. To our surprise, StingS365A/S365A mice protected against HSV-1 infection remarkably well, similar to wild type mice, while Sting–/– mice succumbed to infection very quickly. This challenges the current prevailing view and suggests that STING controls HSV-1 infection through IFN-independent activities. Transcriptomic analysis of wild type, Sting–/– and StingS365A/S365A macrophages and T cells stimulated with Sting agonist DMXAA revealed widespread IFN-independent activities of STING in both cell types and identified many T cell effector functions that are activated by STING independently of IFN. In mouse tumor models, we found that T cells in the tumor experience substantial cell death that was in part mediated by STING. Adoptively transferred Sting–/– T cells were more resistant to cell death in the tumor leading to more effective tumor control compared to wild type and StingS365A/S365A T cells. Together, our data demonstrate that mammalian STING possesses widespread IFN-independent activities that are functionally important for restricting Type I interferon (IFN) response is the most recognized signaling activity of STING, and IFN signaling is commonly believed to be the major (if not the sole) contributor to STING-mediated anti-viral and anti-cancer responses. Here, we genetically mutated mouse Sting serine 365 residue that is critically required for initiating IFN signaling. Sting-S365A mutation in mice precisely ablated IFN-dependent while preserving IFN-independent activities of STING. To our surprise, StingS365A/S365A mice protected against HSV-1 infection remarkably well, similar to wild type mice, while Sting–/– mice succumbed to infection very quickly. This challenges the current prevailing view and suggests that STING controls HSV-1 infection through IFN-independent activities. Transcriptomic analysis of wild type, Sting–/– and StingS365A/S365A macrophages and T cells stimulated with Sting agonist DMXAA revealed widespread IFN-independent activities of STING in both cell types and identified many T cell effector functions that are activated by STING independently of IFN. In mouse tumor models, we found that T cells in the tumor experience substantial cell death that was in part mediated by STING. Adoptively transferred Sting–/– T cells were more resistant to cell death in the tumor leading to more effective tumor control compared to wild type and StingS365A/S365A T cells. Together, our data demonstrate that mammalian STING possesses widespread IFN-independent activities that are functionally important for restricting HSV-1 infection, tumor immune evasion and likely also adaptive T cell immunity. Overall design: The primary T cells and macrophages were isolated from WT, STING-/- and STING-S365A mice, and then treated with DMSO or DMXAA for 16 hours. The total RNA was extracted and applied to RNA-Seq analysis

干扰素基因刺激因子（STING）最被认可的信号通路活性为I型干扰素（Type I interferon, IFN）应答，目前学界普遍认为IFN信号通路是STING介导抗病毒与抗肿瘤应答的核心（即便并非唯一）贡献因素。本研究通过基因编辑手段，对小鼠Sting基因的丝氨酸365位点进行突变——该位点是启动IFN信号通路的关键必需位点。小鼠体内的Sting-S365A突变可精准阻断IFN依赖型活性，同时保留STING的IFN非依赖型活性。令人意外的是，StingS365A/S365A纯合突变小鼠对单纯疱疹病毒1型（Herpes Simplex Virus 1, HSV-1）感染展现出显著的防护效果，与野生型小鼠相当；而Sting–/– 敲除小鼠则迅速死于感染。这一结果挑战了当前的主流观点，表明STING可通过IFN非依赖型通路调控HSV-1感染。对经STING激动剂DMXAA刺激的野生型、Sting–/– 及StingS365A/S365A小鼠的巨噬细胞与T细胞进行转录组分析，结果显示两种细胞类型中均存在广泛的STING介导的IFN非依赖型活性，并鉴定出多种可被STING以IFN非依赖方式激活的T细胞效应功能。在小鼠肿瘤模型中，本研究发现肿瘤内的T细胞会发生大量细胞死亡，其中部分过程由STING介导。过继转移的Sting–/– T细胞在肿瘤内的细胞死亡抗性更强，相较于野生型及StingS365A/S365A T细胞，可实现更有效的肿瘤控制。综上，本研究数据表明，哺乳动物STING具备广泛的IFN非依赖型活性，这些活性在限制HSV-1感染、抑制肿瘤免疫逃逸以及可能的适应性T细胞免疫中发挥重要功能。总体实验设计：从野生型（WT）、STING敲除（Sting–/–）及STING-S365A突变小鼠中分离原代T细胞与巨噬细胞，随后分别用二甲基亚砜（DMSO）或DMXAA处理16小时。提取总RNA后进行RNA测序（RNA-Seq）分析。