Introducing the brain: plasticity & double strand DNA breaks (Introduction)

by David Turell , Monday, August 30, 2021, 17:26 (1179 days ago) @ David Turell

A very new finding:

https://www.quantamagazine.org/brain-cells-break-their-dna-to-learn-more-quickly-20210830/

"As an unsettling recent discovery shows, to express learning and memory genes more quickly, brain cells snap their DNA into pieces at many key points, and then rebuild their fractured genome later.

"The finding doesn’t just provide insights into the nature of the brain’s plasticity. It also demonstrates that DNA breakage may be a routine and important part of normal cellular processes — which has implications for how scientists think about aging and disease, and how they approach genomic events they’ve typically written off as merely bad luck.

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"The double-strand breaks seemed to be essential for regulating gene activity important to the neurons’ function. Tsai and her collaborators hypothesized that the breaks essentially released enzymes that were stuck along twisted pieces of DNA, freeing them to transcribe relevant nearby genes quickly. But the idea “was met with a lot of skepticism,” Tsai said. “People simply have a hard time imagining that double-strand breaks can actually be physiologically important.”

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"Now, in a study last month in PLOS ONE, Tsai and her colleagues have shown that this counterintuitive mechanism of gene expression might be prevalent in the brain. This time, instead of using cultured neurons, they looked at cells in the brains of living mice that were learning to associate an environment with an electric shock. When the team mapped genes undergoing double-strand breaks in the prefrontal cortex and hippocampus of mice that had been shocked, they found breaks occurring near hundreds of genes, many of which were involved in synaptic processes related to memory.

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"Equally interesting, however, was that some double-strand breaks were also occurring in the neurons of mice that had not been shocked. “These breaks are occurring just normally in the brain,” said Timothy Jarome, a neuroscientist at Virginia Polytechnic Institute and State University who did not participate in the study but has done related work. “I think that’s the most surprising aspect from this, because it suggests that it’s occurring all the time.”

'In further support of that conclusion, the scientists also observed double-strand breaks in non-neuronal brain cells called glia, in which they regulate a different assortment of genes. The finding implies a role for glia in the formation and storage of memories, and it hints that DNA breakage might be a regulatory mechanism in many other cell types. “It’s probably a broader mechanism than we think it is,” Jarome said."

Comment: The ability to recode DNA instructions quickly by rapid recombination of code is a clever design and explains how plasticity can work speedily.