Transcriptional repression by methylation: Cooperativity between a CpG cluster in the promoter and remote CpG-rich regions

Martin Hug, John Silke, Oleg Georgiev, Sandro Rusconi, Water Schaffner, Koichi Matsuo

Research output: Contribution to journalArticlepeer-review

28 Citations (Scopus)


Cytosine methylation of binding sites for transcription factors is a straightforward mechanism to prevent transcription, while data on an indirect mechanism, by methylation outside of the factor binding sites, are still scarce. We have studied the latter effect using a model promoter construct. For this, a 69 bp G + C rich DNA segment with a cluster of 14 CpG sites was inserted between upstream lexA sites and the TATA box. Transcription was measured in transient transfection assays with lexA-VP16 as an activating factor. When the entire plasmid was methylated at all CpGs before transfection, transcription was blocked (to 3% residual activity), whereas transcription was only mildly inhibited (to 60%) by methylation of a control plasmid that lacked the 69 bp CpG cluster. However, the effect could not simply be attributed to methylation of tile CpG cluster: neither a methylated CpG cluster in an otherwise methylation-free reporter gene plasmid, nor the methylated plasmid with an unmethylated CpG cluster, inhibited transcription considerably (69% and 44% remaining activity, respectively). The data presented here suggest that a minimal length of methylated DNA in the promoter is required for repression, and imply that concomitant methylation of CpGs in the promoter region and in remote sequences can cooperatively block transcription, without the need to methylate any binding sites for transcription factors. We also note that the cooperation for a negative effect described here bears an analogy to transcriptional activation, where a promoter often cooperates with a remote enhancer.

Original languageEnglish
Pages (from-to)251-254
Number of pages4
JournalFEBS Letters
Issue number3
Publication statusPublished - 1996 Feb 5
Externally publishedYes


  • Cooperativity
  • CpG islands
  • CpG methylation
  • Transcriptional silencing

ASJC Scopus subject areas

  • Biophysics
  • Structural Biology
  • Biochemistry
  • Molecular Biology
  • Genetics
  • Cell Biology


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