Epigenetic information in chromatin: the code of entry for DNA repair.

Epigenetic changes are important etiological factors of human cancer. Epigenetic information in chromatin (known as 'histone code') is a fascinating feature used by cells to extend and modulate the genetic (DNA) code. The histone code is thus proposed to be 'read' by cells to regulate accessibility to, and functions of, chromatin DNA. While the role of the epigenetic code involving chromatin modifying/remodeling complexes in transcriptional regulation is well established, it is only recently that these mechanisms have been implicated in DNA damage detection and DNA repair. However, how the components of the DNA damage sensing and repair machinery gain access to broken DNA in compacted chromatin remains a mystery. Recent studies provide important insights into DNA damage- and repair-specific modifications to histones and shed light on how the epigenetic code controls DNA repair.