DNA methylation (promoter methylation)
Function
DNA methylation is a ubiquitous biological process. It occurs in both prokaryotes & eukaryotes, including humans. In this process, DNA methyltransferases catalyze post-replicative addition of a methyl group to N6 of adenine or the C5 or N4 position of cytosine. S-adenosylmethionine (SAM) is the methyl donor.
In higher eurkaryotes, DNA methylation occurs at the C5 position of cytosine to form 5'-methyl deoxycytosine in association with CpG islands. DNA methylation has a role in gene silencing. DNA methylation represses gene expression, through the action of either of 2 proteins that bind methylated CpG dinucleotides (MeCP1 & MeCP2). MeP1 requires methylation of several CpG dinucleotides for binding, whereas MeCP2 can bind a single methylated CpG dinucleotide. MeCP2 also complexes with the Sin3 repressor complex which that contains histone deacetylase activity.
Pathology
Aberrations in DNA methylation have been implicated in cancer & aging.
Physiology
- DNA methylation plays a role in genomic imprinting & embryonic development
- DNA methylation serves, in part, to protect the genome against its own anti-restriction enzymes whose basic function is to hydrolyze naked sequences like those from viruses[4]
More general terms
More specific terms
References
- ↑ Cancer, Principles and Practice of Oncology, 6th ed. DeVita et al (eds), Lippincot and Williams, Philadelphia, 2001, pg 492
- ↑ Fuks et al, Nature Genetics 24:88, 2000
- ↑ Kastan & Skapek, Molecular Biology of Cancer; the cell cycle, In: Cancer, Principles & Practice of Oncology, 6th edition, DeVita et al (eds), Lippincott & Williams, Philadelpha, 2001, pg 91
- ↑ 4.0 4.1 Genes VII, Lewis B., Oxford University Press, NY, 2000
- ↑ L Stephen Coles, in GRG News Brief Feb 28, 2014 About J. Craig Venter's Lecture