The regulation of DNA compactness is regulated in several ways. When DNA strands replicate, each of the new double helix has one strand with methyl groups and one strand that is not methylated.
Below are the main characteristics of DNA Methylation:
- Addition of a methyl group to a cytosine followed by guanines (CpG dinucleotides)
- Methylation of DNA occurs mostly on cytosines or adenines (5-methyl cytosine)
- Methylation of DNA inhibits transcription of some genes
- CpG islands are sites of methylation in human DNA
- Enzymatic process is carried out by DNA methyltransferases (DNMTs)
- CpG islands have been related to tumorigenesis
- DNA methylation prevents certain genes from being expressed
- DNA methylation is usually a repressive mark and can control transcription by inhibition
- Examples of DNA methylation cellular functions:
- Important in embryonic development
- Genomic imprinting
- X inactivation
- Cellular differentiation and proliferation
