Biliverdin inhibits hepatitis C virus nonstructural 3/4A protease activity: Mechanism for the antiviral effects of heme oxygenase?§

Authors

  • Zhaowen Zhu,

    1. Department of Internal Medicine and Research Service, Veterans Administration Medical Center, Iowa City, IA
    2. Department of Internal Medicine of the Roy G. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA
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  • Anne T. Wilson,

    1. Department of Internal Medicine of the Roy G. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA
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  • Bruce A. Luxon,

    1. Department of Internal Medicine of the Roy G. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA
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  • Kyle E. Brown,

    1. Department of Internal Medicine and Research Service, Veterans Administration Medical Center, Iowa City, IA
    2. Free Radical and Radiation Biology Program of the Department of Radiation Oncology Carver College of Medicine, University of Iowa, Iowa City, IA
    3. Department of Internal Medicine of the Roy G. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA
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  • M. Meleah Mathahs,

    1. Department of Internal Medicine and Research Service, Veterans Administration Medical Center, Iowa City, IA
    2. Department of Internal Medicine of the Roy G. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA
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  • Sarmistha Bandyopadhyay,

    1. Department of Internal Medicine of the Roy G. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA
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  • Anton P. McCaffrey,

    1. Department of Internal Medicine of the Roy G. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA
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  • Warren N. Schmidt

    Corresponding author
    1. Department of Internal Medicine and Research Service, Veterans Administration Medical Center, Iowa City, IA
    2. Department of Internal Medicine of the Roy G. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, IA
    • Department of Internal Medicine, University of Iowa Hospitals and Clinics, 200 Hawkins Drive, 4553 JCP Iowa City, IA 52242
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    • fax: 319-356-7918.


  • Supported in part by Merit Review grants from the Veterans Administration (K.E.B.), the National Institutes of Health R21 DK068453-01A1 and VA Merit Review (W.N.S.), RO1 DK058597-4 (B.A.L.), and the University of Iowa Carver Trust Foundation (W.N.S. and A.P.M.), and the American Cancer Society Seed Award (Z.Z.).

  • Presented in part at the American Association for the Study of Liver Diseases, 50th Annual Meeting, San Francisco, CA, 2008 and 2009, abstracts #1905 and #791, respectively.

  • §

    Potential conflict of interest: Dr. Schmidt is on the speakers' bureau of Schering and is a consultant for Gilead.

Abstract

Induction of heme oxygenase-1 (HO-1) inhibits hepatitis C virus (HCV) replication. Of the products of the reaction catalyzed by HO-1, iron has been shown to inhibit HCV ribonucleic acid (RNA) polymerase, but little is known about the antiviral activity of biliverdin (BV). Herein, we report that BV inhibits viral replication and viral protein expression in a dose-dependent manner in replicons and cells harboring the infectious J6/JFH construct. Using the SensoLyte 620 HCV Protease Assay with a wide wavelength excitation/emission (591 nm/622 nm) fluorescence energy transfer peptide, we found that both recombinant and endogenous nonstructural 3/4A (NS3/4A) protease from replicon microsomes are potently inhibited by BV. Of the tetrapyrroles tested, BV was the strongest inhibitor of NS3/4A activity, with a median inhibitory concentration (IC50) of 9 μM, similar to that of the commercial inhibitor, AnaSpec (Fremont, CA) #25346 (IC50 5 μM). Lineweaver-Burk plots indicated mixed competitive and noncompetitive inhibition of the protease by BV. In contrast, the effects of bilirubin (BR) on HCV replication and NS3/4A were much less potent. Because BV is rapidly converted to BR by biliverdin reductase (BVR) intracellularly, the effect of BVR knockdown on BV antiviral activity was assessed. After greater than 80% silencing of BVR, inhibition of viral replication by BV was enhanced. BV also increased the antiviral activity of α-interferon in replicons. Conclusion: BV is a potent inhibitor of HCV NS3/4A protease, which likely contributes to the antiviral activity of HO-1. These findings suggest that BV or its derivatives may be useful in future drug therapies targeting the NS3/4A protease. (HEPATOLOGY 2010;52:1897–1905)

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