LMP1 Association With CD63 in Endosomes and Secretion via Exosomes Limits Constitutive NF-κB Activation

EMBO J. 2011 Jun 1;30(11):2115-29. doi: 10.1038/emboj.2011.123. Epub 2011 Apr 28.

Abstract

The ubiquitous Epstein Barr virus (EBV) exploits human B-cell development to establish a persistent infection in ∼90% of the world population. Constitutive activation of NF-κB by the viral oncogene latent membrane protein 1 (LMP1) has an important role in persistence, but is a risk factor for EBV-associated lymphomas. Here, we demonstrate that endogenous LMP1 escapes degradation upon accumulation within intraluminal vesicles of multivesicular endosomes and secretion via exosomes. LMP1 associates and traffics with the intracellular tetraspanin CD63 into vesicles that lack MHC II and sustain low cholesterol levels, even in 'cholesterol-trapping' conditions. The lipid-raft anchoring sequence FWLY, nor ubiquitylation of the N-terminus, controls LMP1 sorting into exosomes. Rather, C-terminal modifications that retain LMP1 in Golgi compartments preclude assembly within CD63-enriched domains and/or exosomal discharge leading to NF-κB overstimulation. Interference through shRNAs further proved the antagonizing role of CD63 in LMP1-mediated signalling. Thus, LMP1 exploits CD63-enriched microdomains to restrain downstream NF-κB activation by promoting trafficking in the endosomal-exosomal pathway. CD63 is thus a critical mediator of LMP1 function in- and outside-infected (tumour) cells.

Publication types

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

MeSH terms

  • Antigens, CD / metabolism*
  • Cell Line
  • Endosomes / metabolism*
  • Exosomes / metabolism*
  • Herpesvirus 4, Human / immunology*
  • Herpesvirus 4, Human / pathogenicity
  • Humans
  • NF-kappa B / metabolism*
  • Platelet Membrane Glycoproteins / metabolism*
  • Protein Binding
  • Protein Transport
  • Tetraspanin 30
  • Viral Matrix Proteins / metabolism*

Substances

  • Antigens, CD
  • CD63 protein, human
  • EBV-associated membrane antigen, Epstein-Barr virus
  • NF-kappa B
  • Platelet Membrane Glycoproteins
  • Tetraspanin 30
  • Viral Matrix Proteins