Pro-apoptotic function of HBV X protein is mediated by interaction with c-FLIP and enhancement of death-inducing signal

Kyun Hwan Kim, Baik L. Seong

Research output: Contribution to journalArticle

110 Citations (Scopus)

Abstract

Despite its implication in the progression of hepatitis B virus (HBV)-associated liver disease, the pro-apoptotic function of HBx protein remains poorly understood. We show that the expression of HBx leads to hyperactivation of caspase-8 and caspase-3 upon treatment with tumor necrosis factor-α (TNF-α) or anti-Fas antibody, and this activation is correlated with the sensitivity to apoptosis. We demonstrate cytoplasmic co-localization and direct interaction between HBx and the cellular FLICE inhibitory protein (c-FLIP), a key regulator of the death-inducing signaling complex (DISC). Deletion analysis shows that the death effector domain I (DED1) of c-FLIP is important for the observed interaction. Overexpression of c-FLIP rescued the cells from HBx-mediated apoptosis, with both the full-length HBV genome and HBx expression vectors. Moreover, c-FLIP and caspase-8 inhibitor considerably protected cells from HBx-mediated apoptosis. These data suggest that HBx abrogates the apoptosis-inhibitory function of c-FLIP and renders the cell hypersensitive towards the TNF-α apoptotic signal even below threshold concentration. This provides a novel mechanism for deregulation of hepatic cell growth in HBV patients and a new target for intervention in HBV-associated liver cancer and disease.

Original languageEnglish
Pages (from-to)2104-2116
Number of pages13
JournalEMBO Journal
Volume22
Issue number9
DOIs
Publication statusPublished - 2003 May 1

All Science Journal Classification (ASJC) codes

  • Neuroscience(all)
  • Molecular Biology
  • Biochemistry, Genetics and Molecular Biology(all)
  • Immunology and Microbiology(all)

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