Epstein-Barr virus independent dysregulation of UBP43 expression alters interferon-stimulated gene expression in Burkitt lymphoma

PLoS One. 2009 Jun 24;4(6):e6023. doi: 10.1371/journal.pone.0006023.

Abstract

Epstein-Barr virus (EBV) persists as a life-long latent infection within memory B cells, but how EBV may circumvent the innate immune response within this virus reservoir is unclear. Recent studies suggest that the latency-associated non-coding RNAs of EBV may actually induce type I (antiviral) interferon production, raising the question of how EBV counters the negative consequences this is likely to have on viral persistence. We addressed this by examining the type I interferon response in Burkitt lymphoma (BL) cell lines, the only in vitro model of the restricted program of EBV latency-gene expression in persistently infected B cells in vivo. Importantly, we observed no effect of EBV on interferon alpha-induced signaling or evidence of type I interferon production, suggesting that EBV in this latent state is silent to the cell's innate antiviral surveillance. We did uncover, however, a defect in the negative feedback control of interferon signaling in a subpopulation of BL lines as was revealed by prolonged interferon-stimulated gene transcription consistent with sustained tyrosine phosphorylation on STAT1 and STAT2. This was due to inadequate induction of expression of the ubiquitin-specific protease UBP43, which removes the ubiquitin-like ISG15 polypeptide conjugated to proteins (ISGylation) in response to type I interferons. Results here are consistent with previous findings in genetically engineered Ubp43(-/-) murine cells that UBP43 down-regulates interferon signaling, independent of its ISG15 isopeptidase activity, by precluding the protein kinase JAK1 from the interferon receptor. This natural deficiency in UBP43 expression may therefore provide a useful model to further probe the biological roles of UBP43 and ISGylation.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Burkitt Lymphoma / metabolism*
  • Cell Line, Tumor
  • Endopeptidases / biosynthesis*
  • Gene Expression Regulation*
  • Gene Expression Regulation, Neoplastic*
  • Gene Expression Regulation, Viral*
  • Interferons / metabolism*
  • Mice
  • Mice, Transgenic
  • Models, Biological
  • Phosphorylation
  • STAT1 Transcription Factor / metabolism
  • Ubiquitin Thiolesterase

Substances

  • STAT1 Transcription Factor
  • STAT1 protein, human
  • Stat1 protein, mouse
  • Interferons
  • Endopeptidases
  • Usp18 protein, mouse
  • USP18 protein, human
  • Ubiquitin Thiolesterase