The cytoplasmic LSm1-7 and nuclear LSm2-8 complexes exert opposite effects on Hepatitis B virus biosynthesis and interferon response

ABSTRACT: Viruses employ various strategies to evade innate immunity. Despite many studies on host or viral gene expression, how the cellular proteome responds to internal or external cues, has not been fully investigated. Using a Hepatitis B Virus (HBV) replication model, we performed proteomic analyses of HBV-replicating cells in G1/S and G2/M phases, as a function of IFN-alpha, providing specific information of how HBV infection, in combination with IFN-alpha, alters the hepatocyte proteome. We identified the conserved LSm (Like-Sm1-8) proteins were differentially expressed as a function of HBV replication and IFN-alpha. Specifically, in G2/M, IFN-alpha increased protein level of LSm1, the unique subunit of cytoplasmic LSm1-7 complex involved in mRNA decay. By contrast, IFN-alpha decreased LSm8, the unique subunit of nuclear LSm2-8 complex, a chaperone of U6 spliceosomal RNA. These results suggest cytoplasmic LSm1-7 has antiviral role, whereas nuclear LSm2-8 complex is pro-viral. Employing HBV replication and infection models, siRNA-mediated knockdown of LSm1 increased the level of all viral RNAs. Conversely, knockdown of LSm8 reduced viral RNA levels, dependent on N6-adenosine methylation (m6A) of the epsilon stem-loop at the 5 end of pre-Core/pregenomic (preC/pg) RNA. Methylated RNA immunoprecipitation (MeRIP) assays demonstrated reduced viral RNA methylation upon LSm8 knockdown, dependent on the m6A modification, suggesting the LSm2-8 complex has a role in mediating this modification. Interestingly, splicing inhibitor Cp028 acting upstream of LSm2-8 complex, suppressed levels of viral RNAs without reducing the m6A modification. This observation suggests Cp028 has novel antiviral effects, likely potentiating IFN-alpha -mediated suppression of HBV biosynthesis.

INSTRUMENT(S): Orbitrap Fusion Lumos, Q Exactive HF

ORGANISM(S): Hepatitis B Virus (ncbitaxon:10407)

SUBMITTER: Ourania Andrisani  

PROVIDER: MSV000089600 | MassIVE | Fri Jun 03 13:06:00 BST 2022

REPOSITORIES: MassIVE