ORMDL3 restrains type I interferon signaling and anti-tumor immunity by promoting RIG-I degradation.

Mounting evidence has demonstrated the genetic association of ORMDL sphingolipid biosynthesis regulator 3 (ORMDL3) gene polymorphisms with bronchial asthma and a diverse set of inflammatory disorders. However, its role in type I interferon (type I IFN) signaling remains poorly defined. Herein, we report that ORMDL3 is a negative modulator of the type I IFN signaling by interacting with mitochondrial antiviral signaling protein (MAVS) and subsequently promoting the proteasome-mediated degradation of retinoic acid-inducible gene I (RIG-I). Immunoprecipitation coupled with mass spectrometry (IP-MS) assays uncovered that ORMDL3 binds to ubiquitin-specific protease 10 (USP10), which forms a complex with and stabilizes RIG-I through decreasing its K48-linked ubiquitination. ORMDL3 thus disrupts the interaction between USP10 and RIG-I, thereby promoting RIG-I degradation. Additionally, subcutaneous syngeneic tumor models in C57BL/6 mice revealed that inhibition of ORMDL3 enhances anti-tumor efficacy by augmenting the proportion of cytotoxic CD8 positive T cells and IFN production in the tumor microenvironment (TME). Collectively, our findings reveal the pivotal roles of ORMDL3 in maintaining antiviral innate immune responses and anti-tumor immunity.