Researchers Report DNA Modifications In Non-dividing Brain Cells
Hopkins scientists report that changes to DNA in brain neurons do occur though these neurons do not divide. They used electric shock to stimulate the brains of live mice. A few hours after administering the brain stimulation, the scientists analyzed two million of the same type of neurons from the brains of stimulated mice.
They studied cytosine, a building block of DNA, at 219,991 sites in these neurons. These sites represented about one percent of all cytosines in the whole mouse genomes.
The research report was published in the October issue of Nature Neuroscience. According to the authors, the finding has major implications for treating psychiatric diseases, neurodegenerative disorders, and for better understanding learning, memory and mood regulation.
They found evidence of an epigenetic change called demethylation — the loss of a methyl group from specific locations — in the non-dividing brain cells’ DNA, challenging the scientific dogma that even if the DNA in non-dividing adult neurons changes on occasion from methylated to demethylated state, it does so very infrequently.
DNA comprises the fixed chemical building blocks of each person or animal’s genome, but the addition or removal of a methyl group at the specific location chemically alters DNA and regulates gene expression, enabling cells with the same genetic code to acquire and activate separate functions. Such changes are referred to as epigenetic.
Previously, the same researchers have reported that electrical brain stimulation, such as that used in electroconvulsive therapy (ECT) for patients with drug resistant depression, resulted in increased brain cell growth in mice, due likely to changes in DNA methylation status.
Source Article: Neuronal activity modifies the DNA methylation landscape in the adult brain. Junjie U Guo, Dengke K Ma, Huan Mo, Madeleine P Ball, Mi-Hyeon Jang, Michael A Bonaguidi, Jacob A Balazer, Hugh L Eaves, Bin Xie, Eric Ford, Kun Zhang, Guo-li Ming, Yuan Gao and Hongjun Song. Nature Neuroscience. 2011;14:Pages:1345–1351 Published online28 August 2011. DOI: 10.1038/nn.2900.