STX17 translocation dependents on STING, while STING-STX17 disassociation dependents on energy crisis. (A) Retention of STX17 on ER depends on STING. STING WT or STING KO cells were transfected with Flag-STX17. After 24 h of transfection, cells were treated with Torin 1 for 3 h or non-treatment. Then cells were fixed and stained by indicated antibodies and images were taken by confocal microscopy. Representative images were shown. Scale bar, 10 µm. (B) STING does not translocate to autophagosomes during autophagy. MEFs stably expressing STING-HA were treated with Torin 1 for 3 h and then stained with indicated antibodies. Scale bar for large images, 5 µm; scale bar for inset images, 1 µm. (C) STING colocalizes with STX17 on ER but dissociates upon autophagic stress. MEFs stably expressing STING-HA and STX17-Flag stained with antibodies against HA and Flag without treatment (upper panel). MEFs stably expressing STING-HA were treated with Torin 1 for 3 h and then stained with antibodies against HA and LC3 (bottom panel). Scale bar for large images, 5 µm; scale bar for inset images, 1 µm. (D) Quantification of the colocalization between STING and STX17. Quantitative analysis of the colocalization between STING and STX17 in D. Data are mean ± SEM for 30 cells.