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Updated: Sep 27, 2026

Identifying Inhibitors of the HBx-DDB1 Interaction Using a Split Luciferase Assay System
Published on: December 21, 2019
Synergistic activation of the serum response element-dependent pathway by hepatitis B virus x protein and
Tadashi Goto1, Naoya Kato, Hideo Yoshida
1Department of Gastroenterology, Graduate School of Medicine, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8655, Japan.
Abstract:
Hepatitis delta virus (HDV) is a naturally occurring satellite of hepatitis B virus (HBV). There are few studies of the effects of the combination of HBV and HDV proteins (HDV antigens [HDAgs]) on intracellular signaling pathways. To understand the influence of HBV and HDV coinfection on hepatocytes, we investigated the effect of HBV proteins and HDAgs on the serum response element (SRE)-dependent pathway. Reporter assays revealed that only HBV X protein (HBx), alone or with the large isoform of HDAg (LHDAg), synergistically activated the SRE-dependent pathway. The effect of HBx and LHDAg on Elk1 or serum response factor (SRF) was examined, because both proteins bind to the SRE. HBx activated the transcriptional ability of Elk1, whereas LHDAg activated the transcriptional ability of SRF. Thus, HBx and LHDAg synergistically activated the SRE-dependent pathway. These results may help us understand clinical phenomena in patients coinfected with HBV and HDV.
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