SUMOylation of RIG-Ⅰ positively regulates the type Ⅰ interferon signaling

Retinoic acid-inducible gene-Ⅰ(RIG-Ⅰ) functions as an intracellular pattern recognition receptor(PRR) that recognizes the 5'-triphosphate moiety of single-stranded RNA viruses to initiate the innate immune response.Previous studies have shown that Lys63-linked ubiquitylation is required for RIG-Ⅰ activation and the downstream anti-viral type Ⅰ interferon(IFN-Ⅰ) induction. Herein we reported that, RIG-Ⅰ was also modified by small ubiquitin-like modifier-1(SUMO-1). Functional analysis showed that RIG-Ⅰ SUMOylation enhanced IFN-Ⅰ production through increased ubiquitylation and the interaction with its downstream adaptor molecule Cardif. Our results therefore suggested that SUMOylation might serve as an additional regulatory tier for RIG-Ⅰ activation and IFN-Ⅰ signaling.