Noncoding RNA has been found to play a key role in forming new memories and overcoming fear, a new study reveals.
DNA that does not code for a protein was previously thought of as 'junk' DNA, despite making up 98 percent of the human genome. But in a new study from the University of Queensland, Australia, researchers identify noncoding DNA with a key role in forming memories and overcoming fearful experiences.
'Until recently, scientists thought the majority of our genes were made up of junk DNA, which essentially didn't do anything,' said Dr Timothy Bredy, lead author of the study. 'But when researchers began to explore these regions, they realised that most of the genome is active and transcribed.'
RNA was classically considered as just a secondary messenger molecule of DNA that was used to code for proteins. The function of RNAs without protein-coding potential was largely unknown. But in recent years, noncoding RNAs have been gaining attention as their role in regulating cellular functions is becoming clearer.
In their latest study, published in Cell Reports, Dr Bredy's team asked whether noncoding RNA is involved in the molecular changes in neurons that drive learning and the loss of fear. Overcoming fear involves forming memories after multiple exposures to an initially scary experience when the experience does no harm.
Using a powerful new sequencing approach, the researchers identified 434 noncoding RNAs with increased expression in the brain during a fear-extinction exercise in mice. These RNAs came from relatively unknown regions of the genome. The team focused on a new gene, which they labelled ADRAM, to understand the role of the noncoding RNA.
ADRAM was found to act as both a scaffold for transporting molecules and as a guide to bind a specific gene in the DNA. ADRAM promoted epigenetic changes on the DNA which increased gene expression, driving memory formation and fear-extinction.
'Our findings suggest that long noncoding RNAs provide a bridge, linking dynamic environmental signals with the mechanisms that control the way our brains respond to fear,' Dr Bredy said.
The team hope the new understanding of how noncoding RNAs affect gene activity can help them work towards developing new tools which selectively target post traumatic stress disorder and phobias.
Sources and References
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ADRAM is an experience-dependent long noncoding RNA that drives fear extinction through a direct interaction with the chaperone protein 14-3-3
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Junk DNA' key to controlling fear
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Study explains how 'Junk DNA' could treat PTSD and phobia
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Junk DNA may be targeted in efforts to remove fear-inducing memories
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