Effects Of Hepatitis B X Protein On Eukaryotic Elongation Factor 1 Alpha 1 By Protein-Protein Interaction

Persistent hepatitis B virus (HBV) infection is closely associated with the development of the acute and chronic forms of hepatitis, and with cirrhosis and hepatocellular carcinoma (HCC). But the exact molecular mechanism of how the virus inducing these diseases remains unclear.HBV harbors a circular, partially double-stranded DNA genome consisting of four open reading frames (ORFs) that encode viral proteins. One such ORF, the X gene, encodes the 154-amino-acid HBV X protein (HBx), which has been showed to have multiple functions. HBx protein may play important role during the infection establishment, host cell apoptosis, hepatocarcinogenesis and other virus-host cell interaction processes. However, mechanism considering the association between HBx and hepatocarcinogenesis is far from been fully understood. It was proved that HBx need the help of host cell proteins to exert its function by binding to them. Current studies indicate that the HBx protein interacting with a number of host factors, including transcriptional factors and molecules involved in intracellular signaling and apoptosis.Although many partners of HBx have been discovered, there may be many other partners remain unknown. In the first part of present study, we performed immunoprecipitation and mass spectrometry to identify Eukaryotic Elongation Factor 1 alpha 1( eEF1a1) as a novel HBx-binding protein. eEF1a1 is a major translational factor. eEF1a-GFP catalyzes the binding of aminoacyl-tRNA to the A-site of the ribosome. It is not only necessary for translation but also take part in cellular processes, including signal transduction, translational control, apoptosis, cytoskeletal organization, virus replication and oncogenic transformation.In the second part of this study, the GST pull-down assay and the Co-immunoprecipitation(Co-IP) assay were employed to further confirming the direct interaction between HBx and eEF1a1.In the third part of this study the influence of HBx in vitro and vivo respectively on eEF1a1 was analyzed. The results demonstrated that HBx could inhibit protein translation and reduce F-actin bundles, suggesting that HBx participated in pathogenesis of HBV through interacting with eEF1a1.