STING, an endoplasmic reticulum (ER) transmembrane protein, mediates innate immune activation upon cGAMP stimulation and is degraded through autophagy. Here, we report that activated STING could be transferred between cells to promote antitumor immunity, a process triggered by RAB22A-mediated non-canonical autophagy. Mechanistically, RAB22A engages PI4K2A to generate PI4P that recruits the Atg12–Atg5–Atg16L1 complex, inducing the formation of ER-derived RAB22A-mediated non-canonical autophagosome, in which STING activated by agonists or chemoradiotherapy is packaged. This RAB22A-induced autophagosome fuses with RAB22A-positive early endosome, generating a new organelle that we name Rafeesome (RAB22A-mediated non-canonical autophagosome fused with early endosome). Meanwhile, RAB22A inactivates RAB7 to suppress the fusion of Rafeesome with lysosome, thereby enabling the secretion of the inner vesicle of the autophagosome bearing activated STING as a new type of extracellular vesicle that we define as R-EV (RAB22A-induced extracellular vesicle). Activated STING-containing R-EVs induce IFNβ release from recipient cells to the tumor microenvironment, promoting antitumor immunity. Consistently, RAB22A enhances the antitumor effect of the STING agonist diABZI in mice, and a high RAB22A level predicts good survival in nasopharyngeal cancer patients treated with chemoradiotherapy. Our findings reveal that Rafeesome regulates the intercellular transfer of activated STING to trigger and spread antitumor immunity, and that the inner vesicle of non-canonical autophagosome originated from ER is secreted as R-EV, providing a new perspective for understanding the intercellular communication of organelle membrane proteins.

STING 是一种内质网 (ER) 跨膜蛋白，在 cGAMP 刺激下介导先天免疫激活，并通过自噬降解。在这里，我们报告激活的 STING 可以在细胞之间转移以促进抗肿瘤免疫，这一过程由 RAB22A 介导的非典型自噬触发。从机制上讲，RAB22A 与 PI4K2A 结合产生 PI4P，后者募集 Atg12–Atg5–Atg16L1 复合物，诱导 ER 衍生的 RAB22A 介导的非经典自噬体的形成，其中包装了由激动剂或放化疗激活的 STING。这种 RAB22A 诱导的自噬体与 RAB22A 阳性早期内体融合，产生一个新的细胞器，我们将其命名为 Rafeesome（R AB22A 介导的非典型自噬体f与早点做一些）。_ 同时，RAB22A 使 RAB7 失活以抑制 Rafeesome 与溶酶体的融合，从而使携带激活 STING 的自噬体内囊泡分泌成为一种新型细胞外囊泡，我们将其定义为 R-EV（R AB22A诱导的细胞外v冰块）。活化的含有 STING 的 R-EVs 诱导 IFNβ 从受体细胞释放到肿瘤微环境，促进抗肿瘤免疫。一致地，RAB22A 增强了 STING 激动剂 diABZI 在小鼠中的抗肿瘤作用，并且高 RAB22A 水平预示着接受放化疗的鼻咽癌患者的良好存活率。我们的研究结果表明，Rafeesome 调节激活的 STING 的细胞间转移以触发和传播抗肿瘤免疫，并且源自 ER 的非经典自噬体的内囊泡分泌为 R-EV，为理解细胞器的细胞间通讯提供了新的视角膜蛋白。