Department of Health Chemistry, Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.
Department of Biological Informatics and Experimental Therapeutics, Graduate School of Medicine, Akita University, Akita, 010-8543, Japan.
Biochem Biophys Res Commun. 2018 Sep 3;503(1):138-145. doi: 10.1016/j.bbrc.2018.05.199. Epub 2018 Jun 7.
Stimulator of interferon genes (STING) is essential for the type I interferon and pro-inflammatory responses against DNA pathogens. In response to the presence of cytosolic DNA, STING translocates from the endoplasmic reticulum (ER) to the Golgi, and activates TANK-binding kinase 1 (TBK1), a cytosolic kinase that is essential for the activation of STING-dependent downstream signalling. The organelles where TBK1 binds to STING remain unknown. Here we show that TBK1 binds to STING at the Golgi, not at the ER. Treatment with brefeldin A, an agent to block ER-to-Golgi traffic, or knockdown of Sar1, a small GTPase that regulates coat protein complex II (COP-II)-mediated ER-to-Golgi traffic, inhibited the binding of TBK1 to STING. Endogenous TBK1 was recruited to the Golgi when STING was transported to the Golgi, as shown by immunofluorescence microscopy. STING variants that constitutively induce the type I interferon response were found in patients with autoinflammatory diseases. Even these disease-causative STING variants could not bind to TBK1 when the STING variants were trapped in the ER. These results demonstrate that the Golgi is an organelle at which STING recruits and activates TBK1 for triggering the STING-dependent type I interferon response.
干扰素基因刺激物（STING）是针对 DNA 病原体的 I 型干扰素和促炎反应所必需的。在细胞质 DNA 存在的情况下，STING 从内质网（ER）易位到高尔基体，并激活 TANK 结合激酶 1（TBK1），TBK1 是一种细胞溶质激酶，对 STING 依赖性下游信号转导的激活至关重要。TBK1 结合 STING 的细胞器仍然未知。在这里，我们表明 TBK1 在高尔基体上而不是内质网上与 STING 结合。用布雷菲德菌素 A（一种阻止 ER 到高尔基体运输的试剂）处理，或敲低 Sar1（一种调节 COP-II 介导的 ER 到高尔基体运输的小 GTPase），抑制了 TBK1 与 STING 的结合。如免疫荧光显微镜所示，当 STING 被转运到高尔基体时，内源性 TBK1 被招募到高尔基体。在自身炎症性疾病患者中发现了组成型诱导 I 型干扰素反应的 STING 变体。即使这些疾病相关的 STING 变体在 STING 变体被困在内质网时也不能与 TBK1 结合。这些结果表明，高尔基体是 STING 募集和激活 TBK1 以触发 STING 依赖性 I 型干扰素反应的细胞器。
