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Updated: Jul 19, 2026

Identifying Inhibitors of the HBx-DDB1 Interaction Using a Split Luciferase Assay System
Published on: December 21, 2019
The interaction of hepatitis B virus X protein and protein phosphatase type 2 Calpha and its effect on IL-6
Ji Su Kim1, Bo young Rho, Tae Ho Lee
1Department of Microbiology and Brain Korea 21 Project for Medical Sciences, Institute for Immunology and Immunological Diseases, Yonsei University College of Medicine, Seoul 120-752, Republic of Korea.
Abstract:
HBx has been suggested as an important determinant mediating the pathological effects of HBV via interacting with various cellular proteins. To identify new HBx-interacting proteins and elucidate a possible mechanism associated with HBx and HBx-interacting proteins in hepatocellular carcinoma, yeast two-hybrid screening was performed. We identified a novel HBx-interacting protein, serine/threonine protein phosphatase PP2Calpha, and investigated the effects of PP2Calpha on HBx-mediated IL-6 regulation. The interaction between endogenous PP2Calpha, and HBx was confirmed by co-immunoprecipitation. Recombinant HBx dose-dependently reduced enzyme activity of recombinant PP2Calphain vitro. While ectopically expressed PP2Calpha in Cos-7 and Huh-7 cells reduced the expression of IL-6, overexpressed HBx with recombinant HBx-expressing adenovirus overcame PP2Calpha-mediated IL-6 downregulation. In the response of IL-6, HBx phosphorylated STAT3 and recovered PP2Calpha-mediated dephosphorylation of STAT3. These results supported that HBx might play a crucial role in HBV-associated hepatocarcinogenesis even in cases where cells express a negative regulator, PP2Calpha.
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