The Linear Ubiquitin Assembly Complex Modulates Latent Membrane Protein 1 Activation of NF-κB and Interferon Regulatory Factor 7

J Virol. 2017 Jan 31;91(4):e01138-16. doi: 10.1128/JVI.01138-16. Print 2017 Feb 15.

Abstract

Recently, linear ubiquitin assembly complex (LUBAC)-mediated linear ubiquitination has come into focus due to its emerging role in activation of NF-κB in different biological contexts. However, the role of LUBAC in LMP1 signaling leading to NF-κB and interferon regulatory factor 7 (IRF7) activation has not been investigated. We show here that RNF31, the key component of LUBAC, interacts with LMP1 and IRF7 in Epstein-Barr virus (EBV)-transformed cells and that LUBAC stimulates linear ubiquitination of NEMO and IRF7. Consequently, LUBAC is required for LMP1 signaling to full activation of NF-κB but inhibits LMP1-stimulated IRF7 transcriptional activity. The protein levels of RNF31 and LMP1 are correlated in EBV-transformed cells. Knockdown of RNF31 in EBV-transformed IB4 cells by RNA interference negatively regulates the expression of the genes downstream of LMP1 signaling and results in a decrease of cell proliferation. These lines of evidence indicate that LUBAC-mediated linear ubiquitination plays crucial roles in regulating LMP1 signaling and functions.

Importance: We show here that LUBAC-mediated linear ubiquitination is required for LMP1 activation of NF-κB but inhibits LMP1-mediated IRF7 activation. Our findings provide novel mechanisms underlying EBV-mediated oncogenesis and may have a broad impact on IRF7-mediated immune responses.

Keywords: IRF7; LMP1; LUBAC; ubiquitination.

Publication types

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

MeSH terms

  • Animals
  • Cell Line, Transformed
  • Cell Transformation, Viral
  • Gene Expression Regulation
  • Gene Knockout Techniques
  • Herpesvirus 4, Human / physiology
  • Humans
  • I-kappa B Kinase / metabolism
  • Interferon Regulatory Factor-7 / metabolism*
  • Mice
  • Multiprotein Complexes / metabolism*
  • NF-kappa B / metabolism*
  • Protein Binding
  • Signal Transduction
  • Ubiquitin / metabolism*
  • Ubiquitin-Protein Ligases / metabolism
  • Ubiquitination
  • Viral Matrix Proteins / metabolism*
  • Virus Latency

Substances

  • EBV-associated membrane antigen, Epstein-Barr virus
  • IKBKG protein, human
  • Interferon Regulatory Factor-7
  • Multiprotein Complexes
  • NF-kappa B
  • Ubiquitin
  • Viral Matrix Proteins
  • RNF31 protein, human
  • Ubiquitin-Protein Ligases
  • I-kappa B Kinase