Ubiquitin-specific peptidase 22 (USP22) regulates the level and function of hepatitis B virus X protein / 中华微生物学和免疫学杂志

ABSTRACT

Objective:To investigate the effects of the interaction between ubiquitin-specific peptidase 22 (USP22) and hepatitis B virus X protein (HBx) on the protein level and the biological function of HBx.Methods:The interactions between HBx and USP22 were analyzed by GST pull-down, co-immunoprecipitation assay and confocal laser scanning assay. USP22 recombinant plasmids or specific siRNA were transiently co-transfected with HBx plasmids. Western blot were used to detect the protein level of HBx. The half-life and degradation pathway of HBx in the transfected cells treated with cycloheximide (CHX) or proteasome inhibitor MG132 were detected. In vivo ubiquitination assay was used to detect the ubiquitination of HBx with USP22 overexpression. Moreover, dual-luciferase reporter assay and colony formation assay were used to analyze the effects of USP22 on the biological function of HBx. Results:USP22 could interact with HBx in vivo and in vitro. USP22 significantly increased the stability of HBx and inhibited the proteasome-mediated degradation of HBx protein by reducing the ubiquitination of HBx, thereby enhancing the biological function of HBx. Conclusions:USP22 inhibited HBx protein degradation through ubiquitin-dependent proteasome pathway, thus enhancing the stability and biological function of HBx.