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Selective interactions between vertebrate polycomb homologs and the SUV39H1 histone lysine methyltransferase suggest that histone H3-K9 methylation contributes to chromosomal targeting of Polycomb group proteins.

Polycomb group (PcG) proteins form multimeric chromatin-associated protein complexes that are involved in heritable repression of gene activity. Two distinct human PcG complexes have been characterized. The EED/EZH2 PcG complex utilizes histone deacetylation to repress gene activity. The HPC/HPH PcG complex contains the HPH, RING1, BMI1, and HPC proteins. Here we show that vertebrate Polycomb homologs HPC2 and XPc2, but not M33/MPc1, interact with the histone lysine methyltransferase (HMTase) SUV39H1 both in vitro and in vivo. We further find that overexpression of SUV39H1 induces selective nuclear relocalization of HPC/HPH PcG proteins but not of the EED/EZH2 PcG proteins. This SUV39H1-dependent relocalization concentrates the HPC/HPH PcG proteins to the large pericentromeric heterochromatin domains (1q12) on human chromosome 1. Within these PcG domains we observe increased H3-K9 methylation. Finally, we show that H3-K9 HMTase activity is associated with endogenous HPC2. Our findings suggest a role for the SUV39H1 HMTase and histone H3-K9 methylation in the targeting of human HPC/HPH PcG proteins to modified chromatin structures.

Pubmed ID: 12101246


  • Sewalt RG
  • Lachner M
  • Vargas M
  • Hamer KM
  • den Blaauwen JL
  • Hendrix T
  • Melcher M
  • Schweizer D
  • Jenuwein T
  • Otte AP


Molecular and cellular biology

Publication Data

August 8, 2002

Associated Grants


Mesh Terms

  • Active Transport, Cell Nucleus
  • Cell Nucleus
  • Centromere
  • Chromosomes
  • Chromosomes, Human, Pair 1
  • HeLa Cells
  • Histone-Lysine N-Methyltransferase
  • Histones
  • Humans
  • Macromolecular Substances
  • Methylation
  • Methyltransferases
  • Polycomb-Group Proteins
  • Precipitin Tests
  • Protein Binding
  • Protein Structure, Tertiary
  • Recombinant Fusion Proteins
  • Repressor Proteins
  • Sequence Homology, Amino Acid
  • Two-Hybrid System Techniques
  • Ubiquitin-Protein Ligases