Prevention of transcriptional silencing by a replicator-binding complex consisting of SWI/SNF, MeCP1, and hnRNP C1/C2

Mol Cell Biol. 2011 Aug;31(16):3472-84. doi: 10.1128/MCB.05587-11. Epub 2011 Jun 20.

Abstract

Transcriptional silencing selectively impedes gene expression. Silencing is often accompanied by replication delay and can be prevented by replicator sequences. Here we report a replicator-binding protein complex involved in the prevention of transcriptional silencing. The protein complex interacts with an essential asymmetric region within the human β-globin Rep-P replicator and includes hnRNP C1/C2, SWI/SNF complex, and MeCP1, which are members of the locus control region (LCR)-associated remodeling complex (LARC). Interaction between LARC and Rep-P prevented transcriptional silencing and replication delay. Transgenes that did not contain the asymmetric LARC-binding region of Rep-P replicated late and exhibited stable silencing that could not be affected by a DNA methylation inhibitor. In contrast, transgenes that contain a mutation of the asymmetric region of Rep-P that could not bind LARC exhibited a silent state that could transiently be reactivated by DNA demethylation. The effect of DNA demethylation was transient, and prolonged exposure to a methylation inhibitor induced distinct, stable, methylation-independent silencing. These observations suggest that the interaction of LARC complex with replicators plays a role in preventing gene silencing and provides support for a novel, epigenetic mechanism of resistance to methylation inhibitors.

Publication types

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

MeSH terms

  • Animals
  • Cell Line, Tumor
  • Chromosomal Proteins, Non-Histone*
  • DNA-Binding Proteins*
  • Epigenesis, Genetic
  • Gene Silencing*
  • Heterogeneous-Nuclear Ribonucleoprotein Group C*
  • Histone Deacetylases*
  • Humans
  • Locus Control Region
  • Mice
  • Multiprotein Complexes / genetics
  • Multiprotein Complexes / physiology*
  • Transcription Factors*
  • Transcription, Genetic*
  • Transgenes

Substances

  • Chromosomal Proteins, Non-Histone
  • DNA-Binding Proteins
  • Heterogeneous-Nuclear Ribonucleoprotein Group C
  • MeCP1 histone deacetylase complex, human
  • Multiprotein Complexes
  • SWI-SNF-B chromatin-remodeling complex
  • Transcription Factors
  • Histone Deacetylases