Epigenetics is a term used to refer to the mechanism of regulating gene expression by an acquired modification and the maintenance of that modification without any changes in DNA sequence. DNA methylation and histone chemical modification, among other things, are involved in this mechanism. DNA methylation plays a role in suppressing gene expression, whereas histone chemical modification is involved in activation or suppression of gene expression through such things as transcription regulation or chromatin structural change.
Cytosines (C) undergo methylation in CpG dinucleotides in animal genomic DNA and in CpG and CpNpG sequences in plants. CpG sequences are present sporadically in many genomic regions, but they occur at a high frequency in regions called CpG islands. These islands tend to overlap with gene regulatory regions and their length ranges from 500 to 2000 base pairs. In human and mouse genomes, about 70% of CpG dinucleotides outside of CpG islands have a methylated cytosine; however, cytosines within CpG islands of expressed genes are not methylated. Methylation of CpG islands generally leads to chromatin condensation and suppression of gene transcription. The primary focus of DNA methylation analysis is the methylation status of these CpG islands.
DNA Methylation Analysis
Techniques developed to assay DNA methylation are classified below, including bisulfite sequencing, combined bisulfite restriction analysis (COBRA) and methylation specific PCR (MSP). They each have their own distinct features; select a suitable technique that meets your experimental objectives.
Tools for Modification Enrichment of Epigenetic Marks