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Hepatology Nov (2003); 38(5):1258-66
Hepatitis B virus X protein regulates transactivation activity and protein stability of the cancer-amplified transcription coactivator ASC-2.
Kong HJ, Park MJ, Hong S, Yu HJ, Lee YC, Choi YH, Cheong J
Department of Molecular Biology, Pusan National University, Busan, Korea.
Abstract: Hepatitis B virus X protein (HBx) is a transcriptional coactivator that plays a significant role in the regulation of genes involved in inflammation and cell survival. A recently identified cellular coactivator, activating signal cointegrator 2 (ASC-2), is enriched in liver cancer cells and associates with many transcription factors that are active in hepatocytes. The tissue colocalization of these 2 proteins, in view of their similar regulatory functions, led us to examine whether HBx and ASC-2 cooperate in transcriptional activation of gene expression. Glutathione S-transferase (GST) pull-down assays and mammalian 2-hybrid analysis show that the transactivation domain of HBx interacts with the C-terminal domain of ASC-2. In fact, these 2 proteins associated in a ternary complex that included the transcriptional activator retinoid X receptor (RXR). Mechanistically, on expression of HBx, the half-life of the ASC-2 coactivator is observed to increase in concordance with the observed increase in ASC-2-dependent coactivation of transcription. In conclusion, these results show that HBx stabilizes the cellular coactivator ASC-2 through direct protein-protein interaction, affecting the regulation of genes actively transcribed in liver cancer cells.
[PUBMED: 14578865] Download Biogrid Interactions in a variety of formats including PSI FormatPUBMED
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Chris Stark, Bobby-Joe Breitkreutz, Teresa Reguly, Lorrie Boucher, Ashton Breitkreutz, Mike Tyers.
Nucleic Acids Res. Jan 1;34:D535-9.