Epigenetic memory and its role

· TGI - Epigenetics
Authors

Epigenetic Islands in a Genetic Ocean

published in Science 9 November 2012: Vol. 338 no. 6108 pp. 756-757
DOI: 10.1126/science.1227243

DNA methylation denotes the addition of a methyl group to DNA, which in eukaryotes occurs predominantly at cytosines that are adjacent to guanine (CG). Because methylation does not alter the DNA sequence, it is referred to as an epigenetic mark.

English: This image shows a DNA molecule that ...

English: This image shows a DNA molecule that is methylated on both strands on the center cytosine. DNA methylation plays an important role for epigenetic gene regulation in development and cancer. The picture shows the crystal structure of a short DNA helix with sequence “accgcCGgcgcc”, which is methylated on both strands at the center cytosine. The structure was taken from the Protein Data Bank (accession number 329D), rendering was performed with VMD and post-processing was done in Photoshop. (Photo credit: Wikipedia)

The sequence symmetry of the CG dinucleotide enables propagation of the methyl mark through cell division in a process that is mechanistically well understood. This inheritability makes DNA methylation highly attractive as a potential means to store information in a form of epigenetic memory that regulates genes over developmental processes or in response to environmental conditions. However, it has proven difficult to substantiate this function because it requires showing not only that a DNA methylation pattern coincides with a particular transcriptional state, but more importantly, that it controls it.

source: sciencemag

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