Inhibitory Effect Of TRIM14 On Hepatitis B Virus And Its Mechanism

Helpatitis B virus(HBV)infection is a chronic viral infection with high infection rate which is still an important public health problem in China and around the world.HBV infection can lead to chronic hepatitis,cirrhosis and even liver cancer.There is currently no cure for HBV infection.HBV is a small enveloped virus containing only the 3.2 kb genome and has a precise genomic structure.Important proteins in the life cycle of HBV include core protein(HBcAg),E antigen(HBeAg),surface antigen(HBsAg),and X protein HBx.The expression of these proteins is regulated by HBV promoters.TRIM family proteins play an important role in antiviral innate immunity with E3 ubiquitlin ligase activity.The TRIM family possess a conserved structure,including a RING domain,one or two B-box domain,and a coiled-coil domain in N-terminal.Most of the TRIM proteins contain a B30.2 domain(PRYSPRY)at the C-terminus,TRIM family participate in many physiological processes,including cell differentiation,proliferation,carcinogenesis,autophagy,and activation of innate immunity.Recent years,the role of various TRIM proteins in antiviral innate immunity has been discovered,such as TRIM5?,TRIM11,TRIM19,TRIM22,and TRIM25.And many TRIM proteins are closely related to interferon responses,indicating that TRIM family proteins are a new class of novel antiviral innate immune molecules.Therefore,we hope to study the role of TRIM protein in anti-HBV response.Our research mainly includes three parts.The first part mainly screens TRIM protein which has inhibitory effect on HBV in Hepatoma cell lines HepG2 by constructing TRIM family expression plasmids.We found that TRIM14 has a particularly significant ability to inhibit HBV.Further experiments showed that TRIM14 had strong inhibitory effects on HBsAg,HBeAg,HBcAg as well as the transcriptional levels and DNA levels of HBV in both HepG2 and HBV cell infection model HepG2-NTCP.And knockdown of TRIM14 enhance the replication of HBV.In the second part,we further explored the effect of TRIM14 in vivo.By co-injecting TRIM14 expression plasmid and HBV replicon in a hydrodynamic injection mouse model,TRIM14 can significantly inhibit HBV virology in serum and liver of mice.The third part of the study focused on the mechanism of TRIM14 anti-HBV action.We found TRIM14 can efficiently activate the type-I IFN response and NF-?B signaling pathway,and the inhibition of HBV by TRIM 14 is largely dependent on the activation of NF-?B signaling pathway.However,the mechanism of TRIM 14 inhibit HBV does not depend on HBx which is the important protein of the HBV replication cycle.Studies on the TRIM14 lacking the PRYSPRY domain revealed the inhibitory effect of TRIM14 on HBV disappeared,indicating the PRYSPRY domain is critical in the anti-HBV process of TRIM 14.By constructing a fluorescent reporter gene for the HBV promoter we found TRIM 14 is able to inhibit the activity of the HBV core promoter as well as the S promoter.Thereby inhibiting the transcription level of HBV.In summary,the innate immune molecule TRIM 14 can inhibit HBV protein expression and gene replication in vitro and a mouse model of hydrodynamic inj ection;TRIM14 can activate type I IFN response and NF-?B signal pathway.TRIM14 inhibits HBV core promoter and S promoter activity.These results suggest that TRIM14 may act as an innate immune activator and a transcriptional repressor to inhibit HBV.This study will help to further elucidate the body's resistance to HBV infection.And the anti-HBV mechanism based on the innate immune molecule TRIM 14 may have potential value for the therapeutic application of HBV.