The Ubiquitin-specitic Protease 19 Negatively Regulates Cellular Antiviral Immune Response By Promoting TBK1 Degradation

The innate immune system can identify the pathogenic microorganisms and tissue damage through producing cytokines for host defense. Immune cells recognize virus RNA, Cytoplasmic DNA and bacterial cell wall components lipopolysaccharide by pattern recognition receptors (pattern recognition receptor, PRR)-receptor proteins pairs, including RIG-I-MAVS,cGAS-STING and TLR3/4-TRIF. These signal molecules can cause type I interferon production after phosphorylation of transcription factor IRF3 (Interferon regulatory factor 3)by activating downstream kinase TBK1, resulting in type Ⅰ IFN production.USP 19 (ubiquitin-specific protease 19, USP19) is a member of DUB (deubiquitin enzyme, DUB).USP19 is predominantly localized in the cytosol despite having a transmembrane domain, and the transmembrane appears to be interact with its own catalytic domain,resulting in autoinhibition of its deubiquitinating activity.USP19 could regulate cell proliferation through stabilize KPC1(Kip ubiquitination-promoting complex 1,KPC1),a ubiquitin ligase for the cyclin-dependant kinase inhibitor p27Kip1. USP19 was found to be up-regulated on the condition of skeletal muscle atrophy and hypoxia condition, indicating its important role in both of them. Also USP 19 has been confirmed to correlated with ERAD (endoplasmic-reticulum-associated degradation, ERAD), but there is no study report of the regulated function of USP19 in immune antiviral response.Our study found that USP19 could negatively regulate the VSV induced-production of IFN-β.USP19 can negatively regulate the expression of IFN-P and ISRE report gene through dual-luciferase report gene screening, then immunoprecipitation together with dual-luciferase report gene indicating that USP19 negatively regulate the expression of IFN-βby targeting TBK1.The production of IFN-Pand cellular antiviral response can be enhanced when knockdown of USP19 with the stimulates of VSV, poly(I:C) and LPS in THP-1 cells,as well as in Hela cells when infected with VSV after knockdown of USP19.USP19 could combine with TBKl and promote the degradation of TBK1.The combination of USP19 and TBK1 can be enhanced with the prolonged VSV infection, and USP19 might work on TBK1 by Lysosome pathway, but the specific mechanisms still need further research. To sum up, USP19 plays an important role in antiviral immune response, which provides a new target for the development of antiviral drugs.