Epigenome changes in active and inactive Polycomb-group-controlled regions

Achim Breiling, Laura P. O'Neill, Donatella D'Eliseo, Bryan M. Turner, Valerio Orlando*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

44 Scopus citations


The Polycomb group (PcG) of proteins conveys epigenetic inheritance of repressed transcriptional states. In Drosophila, the Polycomb repressive complex 1 (PRC1) maintains the silent state by inhibiting the transcription machinery and chromatin remodelling at core promoters. Using immunoprecipitation of in vivo formaldehyde-fixed chromatin in phenotypically diverse cultured cell lines, we have mapped PRC1 components, the histone methyl transferase (HMT) Enhancer of zeste (E(z)) and histone H3 modifications in active and inactive PcG-controlled regions. We show that PRC1 components are present in both cases, but at different levels. In particular, active target promoters are nearly devoid of E(z) and Polycomb. Moreover, repressed regions are trimethylated at lysines 9 and 27, suggesting that these histone modifications represent a mark for inactive PcG-controlled regions. These PcG-specific repressive marks are maintained by the action of the E(z) HMT, an enzyme that has an important role not only in establishing but also in maintaining PcG repression.

Original languageEnglish (US)
Pages (from-to)976-982
Number of pages7
JournalEMBO reports
Issue number10
StatePublished - Oct 2004
Externally publishedYes


  • E(z)
  • Histone methylation
  • PRC1
  • Polycomb
  • Transcriptional repression

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Genetics


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