Alterations in epigenetic regulation, processes that affect the availability of genes for transcription and hence their expression levels, are known to have a role in diseases such as cancer. Growing evidence suggests that epigenetic changes are also involved in aging. DNA methylation is one form of epigenetic regulation. Several studies have reported that methylation declines with age, but the mechanism underlying this decline had not been identified. A study published this month in (Nature Neuroscience published online 1 July 2012; doi:10.1038/nn3151) showed that age-related decline in cognitive function in mice is linked to decreased expression levels of the methylation enzyme Dnmt3a1.
Levels of Dnmt3a1 were lower in 18-month-old mice than in 3-month-old mice, and the older mice also had poorer performance on learning and memory tasks. Using an adenoviral vector to boost Dnmt3a1 in the hippocampal neurons of older mice increased both methylation and learning ability, and using short hairpin RNA to reduce Dnmt3a1 in young mice worsened their performance in memory tasks.
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