The subcellular localization and intracellular trafficking of Toll-like receptors (TLRs) critically regulate TLRs-mediated antimicrobial immunity and autoimmunity. Here, it is demonstrated that the E3 ubiquitin ligase RNF115 inhibits the post-endoplasmic reticulum (ER) trafficking of TLRs and TLRs-mediated immune responses by catalyzing ubiquitination of the small GTPases RAB1A and RAB13. It is shown that the 14-3-3 chaperones bind to AKT1-phosphorylated RNF115 and facilitate RNF115 localizing on the ER and the Golgi apparatus. RNF115 interacts with RAB1A and RAB13 and catalyzes K11-linked ubiquitination on the Lys49 and Lys61 residues of RAB1A and on the Lys46 and Lys58 residues of RAB13, respectively. Such a modification impairs the recruitment of guanosine diphosphate (GDP) dissociation inhibitor 1 (GDI1) to RAB1A and RAB13, a prerequisite for the reactivation of RAB proteins. Consistently, knockdown of RAB1A and RAB13 in Rnf115 +/+ and Rnf115 −/− cells markedly inhibits the post-ER and the post-Golgi trafficking of TLRs, respectively. In addition, reconstitution of RAB1A K49/61R or RAB13 K46/58R into Rnf115 +/+ cells but not Rnf115 −/− cells promotes the trafficking of TLRs from the ER to the Golgi apparatus and from the Golgi apparatus to the cell surface, respectively. These findings uncover a common and step-wise regulatory mechanism for the post-ER trafficking of TLRs.

The balance between antioxidants and reactive oxygen species (ROS) critically regulates tumor initiation and progression. However, whether and how the tumor-favoring redox status is controlled by cytokine networks remain poorly defined. Here, it is shown that IL-36 and IL-36Ra reciprocally regulate the progression of non-small cell lung cancer (NSCLC) by modulating glutathione metabolism and ROS resolution. Knockout, inhibition, or neutralization of IL-36 significantly inhibits NSCLC progression and prolongs survival of the Kras LSL-G12D/+ Tp53 fl/fl and Kras LSL-G12D/+ Lkb1 fl/fl mice after tumor induction, whereas knockout of IL-36Ra exacerbates tumorigenesis in these NSCLC mouse models and accelerates death of mice. Mechanistically, IL-36 directly upregulates an array of genes involved in glutathione homeostasis to reduce ROS and prevent oxidative stress-induced cell death, which is mitigated by IL-36Ra or IL-36 neutralizing antibody. Consistently, IL-36 staining is positively and negatively correlated with glutathione biosynthesis and ROS in human NSCLC tumor biopsies, respectively. These findings highlight essential roles of cytokine networks in redox for tumorigenesis and provide potential therapeutic strategy for NSCLC.

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