The quest for mammalian Polycomb response elements: are we there yet?

Chromosoma. 2016 Jun;125(3):471-96. doi: 10.1007/s00412-015-0539-4. Epub 2015 Oct 9.


A long-standing mystery in the field of Polycomb and Trithorax regulation is how these proteins, which are highly conserved between flies and mammals, can regulate several hundred equally highly conserved target genes, but recognise these targets via cis-regulatory elements that appear to show no conservation in their DNA sequence. These elements, termed Polycomb/Trithorax response elements (PRE/TREs or PREs), are relatively well characterised in flies, but their mammalian counterparts have proved to be extremely difficult to identify. Recent progress in this endeavour has generated a wealth of data and raised several intriguing questions. Here, we ask why and to what extent mammalian PREs are so different to those of the fly. We review recent advances, evaluate current models and identify open questions in the quest for mammalian PREs.

Keywords: Drosophila; Epigenetics; Mammal; Polycomb; Polycomb response element; Trithorax.

Publication types

  • Review

MeSH terms

  • Animals
  • Chromosomal Proteins, Non-Histone / genetics
  • CpG Islands / genetics
  • DNA-Binding Proteins / genetics
  • Drosophila Proteins / genetics
  • Drosophila melanogaster / genetics*
  • Genes, Homeobox / genetics
  • Histones / metabolism
  • Humans
  • Mice
  • Polycomb Repressive Complex 1 / genetics*
  • Polycomb Repressive Complex 2 / genetics*
  • Polycomb-Group Proteins / genetics*
  • Protein Processing, Post-Translational
  • Response Elements / genetics*
  • Transcription Factors / metabolism


  • Chromosomal Proteins, Non-Histone
  • DNA-Binding Proteins
  • Drosophila Proteins
  • Histones
  • Polycomb-Group Proteins
  • Transcription Factors
  • trx protein, Drosophila
  • Polycomb Repressive Complex 2
  • Polycomb Repressive Complex 1