EBV-encoded EBNA-6 binds and targets MRS18-2 to the nucleus, resulting in the disruption of pRb-E2F1 complexes

Proc Natl Acad Sci U S A. 2008 Apr 8;105(14):5489-94. doi: 10.1073/pnas.0801053105. Epub 2008 Apr 7.

Abstract

Epstein-Barr virus (EBV), like other DNA tumor viruses, induces an S-phase in the natural host cell, the human B lymphocyte. This is linked with blast transformation. It is believed that the EBV-encoded nuclear antigen 6 (EBNA-6) is involved in the regulation of cell cycle entry. However, the possible mechanism of this regulation is not approached. In our current study, we found that EBNA-6 binds to a MRPS18-2 protein, and targets it to the nucleus. We found that MRPS18-2 binds to both hypo- and hyperphosphorylated forms of Rb protein specifically. This binding targets the small pocket of pRb, which is a site of interaction with E2F1. The MRPS18-2 competes with the binding of E2F1 to pRb, thereby raising the level of free E2F1. Our experimental data suggest that EBNA-6 may play a major role in the entry of EBV infected B cells into the S phase by binding to and raising the level of nuclear MRPS18-2, protein. This would inhibit pRb binding to E2F1 competitively and lift the block preventing S-phase entry.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Active Transport, Cell Nucleus*
  • Antigens, Viral / metabolism*
  • Antigens, Viral / physiology
  • Cell Line
  • DNA, Complementary
  • E2F1 Transcription Factor / metabolism*
  • Epstein-Barr Virus Nuclear Antigens / metabolism*
  • Epstein-Barr Virus Nuclear Antigens / physiology
  • Herpesvirus 4, Human / chemistry
  • Humans
  • Mitochondrial Proteins / metabolism*
  • Multiprotein Complexes / metabolism
  • Retinoblastoma Protein / metabolism*
  • Ribosomal Proteins / metabolism*
  • Transfection

Substances

  • Antigens, Viral
  • DNA, Complementary
  • E2F1 Transcription Factor
  • E2F1 protein, human
  • EBNA-6 protein, human herpesvirus 4
  • Epstein-Barr Virus Nuclear Antigens
  • Mitochondrial Proteins
  • Multiprotein Complexes
  • Retinoblastoma Protein
  • Ribosomal Proteins
  • ribosomal protein S18