Epigenesis: The ability to inherit changes in gene expression that are not recorded in the genome. Epigenesis is helped along by Methylation which sees the change of DNA base cytosine to 5-methylcytosine, and Histone modification.
Lately, a new theory has come to light that suggests that free radicals may be able to control or are responsible for the activity of epigenetic events. It has been known for many years that free radicals bring about cell differentiation by altering the intracellular environment until it is more oxidised. The intracellular presence of free radicals however, is thought to influence the amount of substrate and cofactor available to the enzymes that are responsible for the initiation and continuation of epigenetic events. By making more or less substrate available, free radicals are thought to be able to increase or decrease the development of epialleles.
In order to differentiate, cells must move from a reduced state to an oxidised one which is usually conducted by the production of free radicals. The main protection against damage from free radicals is glutathione (GSH). This GSH has been linked to the enzymes and cofactors involved with epigenetic production. Decreased levels of GSH, has been seen to alter the amount of substrate available for DNA-methylation and histone modification, and as GSH concentration changes in accordance with the amount of free radicals present, the relationship between free radicals and epigenetic development seems hard to deny.
Written by s4152176
References:
1. Hitchler.M, Domann F, An epigenetic perspectoive on the free radical theory of development, Free radical Biology and Medicine, 43:1023-1036, 2007
2. Lertratanangkoon K etal, Alterations of DNA methylation by glutathione depletion, Cancer Res. 120: 149-156;1997
3.Holliday R. etal, Epigenetics: an overview, Developmental Genetics, 15:453-457
4.Rice J, etal Histone methylation versus histone acetylation:new insights into epigenetic regulation, Current Opinion Cell Biology, 13:263-273, 2001
