Requirement of the cyclic adenosine monophosphate response element-binding protein for hepatitis B virus replication

Authors

  • Bo Kyung Kim,

    1. Department of Biochemistry, Korea University College of Medicine, Seoul, Korea
    2. Division of Brain Korea 21 Program for Biomedical Science, Korea University College of Medicine, Seoul, Korea
    Search for more papers by this author
  • Seoung Ok Lim,

    1. Department of Biochemistry, Korea University College of Medicine, Seoul, Korea
    2. Korean Institute of Molecular Medicine and Nutrition, Korea University College of Medicine, Seoul, Korea
    Search for more papers by this author
  • Yun Gyu Park

    Corresponding author
    1. Department of Biochemistry, Korea University College of Medicine, Seoul, Korea
    2. Division of Brain Korea 21 Program for Biomedical Science, Korea University College of Medicine, Seoul, Korea
    3. Korean Institute of Molecular Medicine and Nutrition, Korea University College of Medicine, Seoul, Korea
    • Department of Biochemistry, Korea University College of Medicine, 126-1, 5-ga, Anam-dong, Sungbuk-gu, Seoul 136-701, Korea
    Search for more papers by this author
    • The corresponding author certifies that all of the listed authors participated meaningfully in the study and that they have seen and approved the final manuscript.

    • fax: 82-2-923-0480.


  • Potential conflict of interest: Nothing to report.

Abstract

The cyclic adenosine monophosphate–response element (CRE)-transcription factor complex participates in the regulation of viral gene expression and pathologic processes caused by various viruses. The hepatitis B virus (HBV) enhancer I directs liver-specific transcription of viral genes and contains a CRE sequence (HBV-CRE); however, whether the HBV-CRE and CRE-binding protein (CREB) are required for the HBV life cycle remains to be determined. This study was designed to investigate the role of CREB in HBV replication and gene expression. Sequence-comparison analysis of 984 HBVs reported worldwide showed that the HBV-CRE sequence is highly conserved, indicating the possibility that it plays an important role in the HBV life cycle. The binding of CREB to the HBV-CRE site was markedly inhibited by oligonucleotides containing HBV-CRE and consensus CRE sequences in vitro and in vivo. The HBV promoter activity was demonstrated to be dependent upon the transactivation activity of CREB. Treatment with CRE decoy oligonucleotides reduced HBV promoter activity, and this was reversed by CREB overexpression. The levels of viral transcripts, DNA, and antigens were remarkably decreased in response to the overexpression of CREB mutants or treatment with the CRE decoy oligonucleotides, whereas enhancing CREB activity increased the levels of viral transcripts. In addition, introduction of a three-base mutation into the HBV-CRE led to a marked reduction in HBV messenger RNA synthesis. Conclusion: Taken together, our results demonstrate that both replication and gene expression of HBV require a functional CREB and HBV-CRE. We have also demonstrated that CRE decoy oligonucleotides and the overexpression of CREB mutants can effectively block the HBV life cycle, suggesting that interventions against CREB activity could provide a new avenue to treat HBV infection. (HEPATOLOGY 2008.)

Ancillary