BET proteins promote efficient murine leukemia virus integration at transcription start sites

Proc Natl Acad Sci U S A. 2013 Jul 16;110(29):12036-41. doi: 10.1073/pnas.1307157110. Epub 2013 Jul 1.


The selection of chromosomal targets for retroviral integration varies markedly, tracking with the genus of the retrovirus, suggestive of targeting by binding to cellular factors. γ-Retroviral murine leukemia virus (MLV) DNA integration into the host genome is favored at transcription start sites, but the underlying mechanism for this preference is unknown. Here, we have identified bromodomain and extraterminal domain (BET) proteins (Brd2, -3, -4) as cellular-binding partners of MLV integrase. We show that purified recombinant Brd4(1-720) binds with high affinity to MLV integrase and stimulates correct concerted integration in vitro. JQ-1, a small molecule that selectively inhibits interactions of BET proteins with modified histone sites impaired MLV but not HIV-1 integration in infected cells. Comparison of the distribution of BET protein-binding sites analyzed using ChIP-Seq data and MLV-integration sites revealed significant positive correlations. Antagonism of BET proteins, via JQ-1 treatment or RNA interference, reduced MLV-integration frequencies at transcription start sites. These findings elucidate the importance of BET proteins for MLV integration efficiency and targeting and provide a route to developing safer MLV-based vectors for human gene therapy.

Keywords: retroviral gene therapy; virus–host interactions.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Azepines
  • Cell Cycle Proteins
  • Cell Line, Tumor
  • Chromatin Immunoprecipitation
  • HEK293 Cells
  • High-Throughput Nucleotide Sequencing
  • Host-Pathogen Interactions
  • Humans
  • Integrases / metabolism*
  • Leukemia Virus, Murine / enzymology*
  • Mass Spectrometry
  • Mice
  • NIH 3T3 Cells
  • Nuclear Proteins / antagonists & inhibitors
  • Nuclear Proteins / genetics
  • Nuclear Proteins / metabolism*
  • Proteomics / methods
  • RNA Interference
  • Recombinant Proteins / metabolism*
  • Transcription Factors / antagonists & inhibitors
  • Transcription Factors / genetics
  • Transcription Factors / metabolism*
  • Transcription Initiation Site / physiology*
  • Triazoles
  • Virus Integration / genetics
  • Virus Integration / physiology*


  • (+)-JQ1 compound
  • Azepines
  • BRD4 protein, human
  • Cell Cycle Proteins
  • Nuclear Proteins
  • Recombinant Proteins
  • Transcription Factors
  • Triazoles
  • Integrases