Beyond genome sequences: Epigenetics and the chromatin state

作者：Wako Toshiyuki; Fukui Kiichi^*

来源：Proceedings of the National Academy of Sciences India Section B-Biological Sciences, 2007, 77: 73-84.

• epigenetics
• genome sequences
• chromatin state

Epigenetics is the study of mitotically and/or meiotically heritable changes in gene expression without any change in DNA sequence. The epigenetic information also causes sequence-independent gene silencing and gene regulation during cell differentiation. The epigenetic information determines specific chromosome structure, such as constitutive heterochromatin, facultative heterochromatin and euchromatin. The heterochromatins are transcriptionally silenced, but regulatory mechanisms are completely different between the two types of heterochromatins. The euchromatin is transcriptionally permissive region and contains active-genes. The epigenetic information is defined by epigenetic code, cytosine methylation and histone modifications such as acetylation, methylation and ubiquitination, etc. The key features in constitutive heterochromatin are trimethylation of histone H3 at lysine 9 (H3K9me3) and HP1 family protein, whereas facultative heterochromatin is characterized by H3K27me3 and polycomb group (PcG) proteins. The specific marks of active genes in the euchromatin are H3K4me3 and histone H3/H4 acetylation. These modifications contribute to recruit the specific proteins to chromatin, and to form heterochromatins or euchromatin structure for epigenetic regulation of gene activity.

• 出版日期2007