Redundant mechanisms to form silent chromatin at pericentromeric regions rely on BEND3 and DNA methylation

Mol Cell. 2014 Nov 20;56(4):580-94. doi: 10.1016/j.molcel.2014.10.001. Epub 2014 Nov 6.

Abstract

Constitutive heterochromatin is typically defined by high levels of DNA methylation and H3 lysine 9 trimethylation (H3K9Me3), whereas facultative heterochromatin displays DNA hypomethylation and high H3 lysine 27 trimethylation (H3K27Me3). The two chromatin types generally do not coexist at the same loci, suggesting mutual exclusivity. During development or in cancer, pericentromeric regions can adopt either epigenetic state, but the switching mechanism is unknown. We used a quantitative locus purification method to characterize changes in pericentromeric chromatin-associated proteins in mouse embryonic stem cells deficient for either the methyltransferases required for DNA methylation or H3K9Me3. DNA methylation controls heterochromatin architecture and inhibits Polycomb recruitment. BEND3, a protein enriched on pericentromeric chromatin in the absence of DNA methylation or H3K9Me3, allows Polycomb recruitment and H3K27Me3, resulting in a redundant pathway to generate repressive chromatin. This suggests that BEND3 is a key factor in mediating a switch from constitutive to facultative heterochromatin.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • CCAAT-Enhancer-Binding Proteins
  • Cell Nucleus / metabolism
  • Cells, Cultured
  • Centromere / genetics
  • DNA (Cytosine-5-)-Methyltransferases / metabolism
  • DNA Methylation*
  • DNA-Binding Proteins / physiology*
  • Embryonic Stem Cells / physiology
  • Gene Silencing*
  • Genetic Loci
  • Heterochromatin / genetics*
  • Histones / metabolism
  • Mice, 129 Strain
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Microsatellite Repeats
  • Nuclear Proteins / metabolism
  • Proteome / metabolism
  • Repressor Proteins
  • Ubiquitin-Protein Ligases

Substances

  • BEND3 protein, mouse
  • CCAAT-Enhancer-Binding Proteins
  • DNA-Binding Proteins
  • Heterochromatin
  • Histones
  • Nuclear Proteins
  • Proteome
  • Repressor Proteins
  • DNA (Cytosine-5-)-Methyltransferases
  • DNA methyltransferase 3B
  • Ubiquitin-Protein Ligases
  • Uhrf1 protein, mouse