ARMH3-mediated recruitment of Phosphatidylinositol 4-kinase beta directs Golgi-to-endosome trafficking and activation of the antiviral effector STING

The cGAS-STING pathway mediates cytoplasmic DNA-triggered innate immunity. STING activation is initiated by cyclic-GMP-AMP (cGAMP)-induced translocation from the endoplasmic reticulum and sulfated glycosaminoglycans-induced polymerization at the Golgi. Here we examined the mechanisms underlying STING transport and activation beyond the Golgi. A genome-wide CRISPR–Cas9 screen identified Armadillo-like helical domain-containing protein 3 (ARMH3) as critical for STING activation. Upon cGAMP-triggered translocation, ARMH3 interacted with STING at the Golgi and recruited phosphatidylinositol 4-kinase beta (PI4KB) to synthesize PI4P, which directed STING Golgi-to-endosome trafficking via PI4P-binding proteins AP-1 and GGA2. Disrupting PI4P-dependent lipid transport through RNAi of other PI4P-binding proteins impaired STING activation. Consistently, disturbed lipid composition inhibited STING activation whereas aberrantly elevated cellular PI4P led to cGAS-independent STING activation. Armh3fl/fllLyzCre/Cre mice were susceptible to DNA virus challenge in vivo. Thus, ARMH3 bridges STING and PIK4B to generate PI4P for STING transportation and activation, an interaction conserved in all eukaryotes.cGAS-STING通路介导胞质DNA触发的天然免疫。STING的激活始于环鸟苷酸-腺苷酸（cGAMP）诱导其从内质网转位，以及硫酸化糖胺聚糖介导其在高尔基体发生聚合。本研究探讨了高尔基体之外STING的转运与激活机制。通过全基因组CRISPR-Cas9筛选，我们鉴定出含臂状螺旋结构域蛋白3（ARMH3）是STING激活的关键调控因子。在cGAMP诱导的转位过程中，ARMH3于高尔基体与STING相互作用，并招募磷脂酰肌醇4-激酶β（PI4KB）以合成磷脂酰肌醇4-磷酸（PI4P）；PI4P可通过其结合蛋白AP-1与GGA2引导STING从高尔基体向内涵体转运。通过RNA干扰靶向其他PI4P结合蛋白以破坏PI4P依赖的脂质转运过程，会损害STING的激活。与此一致的是，脂质组成紊乱会抑制STING激活，而细胞内PI4P异常升高则会引发不依赖cGAS的STING激活。体内实验显示，Armh3fl/fl;LyzCre/Cre小鼠对DNA病毒攻毒易感。综上，ARMH3作为桥梁连接STING与PI4KB，通过生成PI4P调控STING的转运与激活，这一相互作用在所有真核生物中均保守存在。