Tuesday, May 18, 2010

Tricks of Epigenetic Memory

It is common knowledge that a person's memory tends to get a bit foggy as he ages. A young person's memory tends to be crisper and quicker than that of a person in senescence. But it is possible that there is a means within our grasp by which we can turn back the clock in the aging brain -- back to a time of quicker and clearer recall, and a stronger grasp of new knowledge.
A new study published in Science sheds some light on how “memory disturbances” in an aging mouse brain are associated with altered “hippocampal chromatin plasticity” — the combination of DNA, histones, and other proteins that make up the chromosomes associated with the hippocampus. Specifically, the study describes an acetyl genetic switch that produces memory impairment in aging 16-month-old mice. Because the acetyl wasn’t present in young 3-month-old mice, the study concludes that it acts as a switch for a cluster of learning and memory genes.

...Dr. Fischer’s research shows that when young mice are learning, an acetyl group binds to a particular point on the histone protein. The cluster of learning and memory genes on the surrounding DNA ends up close to the acetyl group. This acetyl group was missing in the older mice that had been given the same tasks. By injecting an enzyme known to encourage acetyl groups to bind to any kind of histone molecule, Fischer’s team flipped the acetyl genetic switch to the “on” position in the older mice and their learning and memory performance became similar to that of 3-month-old mice. _hplus
Dr Fischer, of the European Neuroscience Institute in Goettingen, Germany, pinpointed a tiny protein called H4K12 that controls genes key to memory and learning in the mouse brain.

...In an accompanying article, Professor David Sweatt , a U.S. neurobiologist, said that turning on H4K12 was likely to help with both Alzheimer's and age-related memory loss.
He said the German results 'provide important proof of principle that this might be a viable approach to therapeutic interventions in ageing'.
'These studies will hopefully lead to more effective prevention strategies to improve quality of life in the aged, as well as contribute to a better understanding of memory function,' he added.
The treatment of other brain conditions, such as schizophrenia and Parkinson's disease, could be improved by finding other switches that act in a similar way.
Dr Marie Janson, of the Alzheimer's Research Trust, said: 'Although in mice, this research gives us clues about how memories are formed and function in the brain.
'We now need to find out if the same processes happen in the human brain.
'This understanding is vital if we are to develop ways to protect the ageing brain from cognitive decline.
'Alzheimer's and other dementias are complex, with many things happening in the brain, so it's likely that we'll need several drugs to treat them effectively._DailyMail

Brain function is inextricably tied to genetic function. The relationship is certainly of a circular nature. If we are to learn to live long and fulfilling lives, we will need to undertand ourselves better, at a much deeper level than we once thought possible.

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