Monday, March 25, 2013

Did you know: DNA damage could be a part of normal learning?

 DNA ligase encircles the double helix
to repair a broken strand of DNA
According to a recent report in Nature Neuroscience a form of DNA damage called double strand breaks (DSB's) exhibit an increase in mice brains that are exposed to new environments. DSB's have long been thought to be associated with age-related illnesses such as Alzheimers. However, this report shows that they are formed during normal brain function as well and may be important in the conversion of neuronal DNA into proteins that are involved in forming memories.

The collaborators from San Francisco were comparing normal mice to genetically modified mice that mimic Alzheimers and were initially surprised to find the DSB's in normal mice. However, after an initial rise in DSB's the levels began to decrease suggesting that a cycle of damage and repair is normal in the learning process. In contrast, the modified mice had higher initial levels of DSB's which rose when exposed to a new environment but were decreased more slowly. So while some formation of DSB's is normal, if the levels are not decreased permanent damage could result.

Article citation:

Physiologic brain activity causes DNA double-strand breaks in neurons, with exacerbation by amyloid-β