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Heterochromatin and Euchromatin—Organization, Boundaries, and Gene Regulation

Epigenetic Regulation and Epigenomics

  1. Annelie Strålfors,
  2. Karl Ekwall

Published Online: 10 OCT 2011

DOI: 10.1002/3527600906.mcb.200400018.pub2

Reviews in Cell Biology and Molecular Medicine

Reviews in Cell Biology and Molecular Medicine

How to Cite

Strålfors, A. and Ekwall, K. 2011. Heterochromatin and Euchromatin—Organization, Boundaries, and Gene Regulation. Reviews in Cell Biology and Molecular Medicine. .

Author Information

  1. Karolinska Institutet, Department of Biosciences and Nutrition, Center for Biosciences, Huddinge, Stockholm, Sweden

Publication History

  1. Published Online: 10 OCT 2011

Abstract

A functional genome is carefully orchestrated into different chromosomal domains of gene activity and noncoding structural domains, such as centromeres. Histone modifications and DNA methylation are examples of epigenetic mechanisms, which determine if a chromosomal region will be in an active “euchromatin” or an inactive “heterochromatin” state. In this chapter, the properties and functions of heterochromatin are described, and details provided as to heterochromatin is assembled and maintained in dividing cells. Heterochromatin ensures genome stability via the centromere structure and the sister chromatid cohesion process, and by inhibiting harmful DNA recombination. Active genes in euchromatin must be protected from the repressive influence of heterochromatin spreading, since heterochromatin formation leads to gene silencing. Here, several mechanisms are portrayed in the cell nucleus which involve chromosomal boundaries, barrier elements, and insulators that partition the genome into euchromatic and heterochromatin domains.

Keywords:

  • Centromere;
  • Epigenetics;
  • Euchromatin;
  • Heterochromatin;
  • Histones;
  • Insulator;
  • Lysine methyltransferases (KMT);
  • Lysine acetyltransferases (KAT);
  • Lysine demethylases (KDM);
  • Nucleosome;
  • RNA interference (RNAi)