Biochemistry Section, Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD.
Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Melbourne, Australia.
J Cell Biol. 2020 Dec 7;219(12). doi: 10.1083/jcb.202009128.
Following the detection of cytosolic double-stranded DNA from viral or bacterial infection in mammalian cells, cyclic dinucleotide activation of STING induces interferon β expression to initiate innate immune defenses. STING activation also induces LC3B lipidation, a classical but equivocal marker of autophagy, that promotes a cell-autonomous antiviral response that arose before evolution of the interferon pathway. We report that STING activation induces LC3B lipidation onto single-membrane perinuclear vesicles mediated by ATG16L1 via its WD40 domain, bypassing the requirement of canonical upstream autophagy machinery. This process is blocked by bafilomycin A1 that binds and inhibits the vacuolar ATPase (V-ATPase) and by SopF, a bacterial effector that catalytically modifies the V-ATPase to inhibit LC3B lipidation via ATG16L1. These results indicate that activation of the cGAS-STING pathway induces V-ATPase-dependent LC3B lipidation that may mediate cell-autonomous host defense, an unanticipated mechanism that is distinct from LC3B lipidation onto double-membrane autophagosomes.
在哺乳动物细胞中检测到病毒或细菌感染的细胞质双链 DNA 后，环状二核苷酸激活 STING 诱导干扰素 β 的表达，从而启动先天免疫防御。STING 的激活还诱导 LC3B 脂质化，这是自噬的经典但有争议的标志，它促进了细胞自主的抗病毒反应，这种反应在干扰素途径进化之前就已经出现。我们报告说，STING 的激活通过其 WD40 结构域诱导 ATG16L1 将 LC3B 脂质化到单膜核周小泡上，绕过了经典的上游自噬机制的要求。这个过程被结合并抑制液泡型 ATP 酶（V-ATPase）的巴弗洛霉素 A1 和 SopF 阻断，SopF 是一种细菌效应物，通过 ATG16L1 催化修饰 V-ATPase 来抑制 LC3B 脂质化。这些结果表明，cGAS-STING 途径的激活诱导了 V-ATPase 依赖性的 LC3B 脂质化，这可能介导细胞自主的宿主防御，这是一种出乎意料的机制，与双膜自噬体上的 LC3B 脂质化不同。
