Oxidative stress sensor Keap1 recognizes HBx protein to activate the Nrf2/ARE signaling pathway, thereby inhibiting hepatitis B virus replication

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抄録

Hepatitis B virus (HBV) infection promotes reactive oxygen species production while paradoxically inducing the expression of antioxidant enzymes. HBV-induced disorders of redox homeostasis are closely associated with the development of hepatic diseases. However, the molecular mechanisms underlying the HBV-induced antioxidant response are poorly understood. The NF-E2-related factor 2 (Nrf2)/antioxidant response element (ARE) signaling pathway is an intrinsic defense mechanism against oxidative stress. We here aim to elucidate the role of the Nrf2/ARE signaling pathway in the HBV life cycle. ARE-driven reporter assays revealed that expression of HBV X protein (HBx), but not HBV core, large HBV surface, or HBV polymerase, strongly enhanced ARE-luciferase activity, suggesting that HBx plays an important role in the HBV-induced antioxidant response. Knockdown of Nrf2 resulted in a marked decrease in HBx-induced ARE-luciferase activity. Immunoblot analysis and immunofluorescence staining suggested that HBx activates Nrf2 by increasing Nrf2 protein levels and enhancing Nrf2 nuclear localization. The oxidative stress sensor Kelch-like ECH-associated protein 1 (Keap1) is required for the ubiquitin-dependent degradation of Nrf2. Coimmunoprecipitation analysis revealed that HBx interacted with Keap1, suggesting that HBx competes with Nrf2 for interaction with Keap1. A cell-based ubiquitylation assay showed that HBx promoted polyubiquitylation of Nrf2 via K6-linked polyubiquitin chains, and that this action may be associated with Nrf2 stabilization. A chromatin immunoprecipitation assay suggested that Nrf2 interacts with the HBV core promoter. Overexpression of Nrf2 strongly suppressed HBV core promoter activity, resulting in a marked reduction in viral replication. Based on the above, we propose that Keap1 recognizes HBx to activate the Nrf2/ARE signaling pathway upon HBV infection, thereby inhibiting HBV replication.

収録刊行物

  • Journal of Virology

    Journal of Virology 97 (10), e01287-23-, 2023-10-31

    American Society for Microbiology

詳細情報 詳細情報について

  • CRID
    1050299749919145216
  • ISSN
    10985514
    0022538X
  • HANDLE
    20.500.14094/0100485257
  • 本文言語コード
    en
  • 資料種別
    journal article
  • データソース種別
    • IRDB

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