The changing faces of HP1: From heterochromatin formation and gene silencing to euchromatic gene expression: HP1 acts as a positive regulator of transcription

Bioessays. 2011 Apr;33(4):280-9. doi: 10.1002/bies.201000138. Epub 2011 Jan 27.


Heterochromatin protein 1 (HP1) is a positive regulator of active transcription in euchromatin. HP1 was first identified in Drosophila melanogaster as a major component of heterochromatin. Most eukaryotes have at least three isoforms of HP1, which are conserved in overall structure but localize differentially to heterochromatin and euchromatin. Although initial studies revealed a key role for HP1 in heterochromatin formation and gene silencing, recent progress has shed light on additional roles for HP1 in processes such as euchromatic gene expression. Recent studies have highlighted the importance of HP1-mediated gene regulation in euchromatin. Here, we focus on recent advances in understanding the role of HP1 in active transcription in euchromatin and how modification and localization of HP1 can regulate distinct functions for this protein in different contexts.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Animals
  • Chromatin Assembly Factor-1 / metabolism
  • Chromosomal Proteins, Non-Histone / chemistry
  • Chromosomal Proteins, Non-Histone / genetics*
  • Chromosomal Proteins, Non-Histone / metabolism
  • DNA Damage
  • DNA Replication
  • Euchromatin / genetics*
  • Euchromatin / metabolism
  • Gene Silencing*
  • Heterochromatin / genetics
  • Heterochromatin / metabolism*
  • Histones / metabolism
  • Humans
  • Origin Recognition Complex / metabolism
  • Phosphorylation
  • Protein Isoforms / chemistry
  • Protein Isoforms / genetics
  • Protein Isoforms / metabolism
  • Protein Processing, Post-Translational
  • Protein Structure, Tertiary
  • Protein Transport
  • Transcriptional Activation*


  • Chromatin Assembly Factor-1
  • Chromosomal Proteins, Non-Histone
  • Euchromatin
  • Heterochromatin
  • Histones
  • Origin Recognition Complex
  • Protein Isoforms
  • heterochromatin-specific nonhistone chromosomal protein HP-1