DNA molecule unwinding from a chromosome inside the nucleus of a cell. (Credit: National Human Genome Research Institute)

 A new and unexpected role for RNA is identified recently: the defence of genome integrity and stability. A study published in the scientific journal Nature shows that an until now unknown class of RNA — the newly christened DDRNA — plays a key role in activation of the molecular alarms necessary to safeguard our genome when DNA damage from internal or external factors occurs.Given the importance of the cellular DNA damage response in aging, in the repression and control of tumour development, and in therapeutic treatments for cancer, the discovery could open promising avenues.Scientific community has attributed a role to RNA that is subordinate to that of DNA: the functional processes of expression of genetic information into proteins. With some known exceptions, such as the classes of tRNA and rRNA involved in the synthesis of proteins, RNA molecules were considered “fleeting” messengers necessary to carry genetic instructions from the nucleus, site of the genome, to the cytoplasm where proteins, the scaffolding of living organisms, are produced.

DDRNA: a barrier against tumour development

The DNA Damage Response or DDR is the reaction that a cell triggers to maintain its genomic integrity: when a DNA break is detected, the growth and proliferation of damaged cells are temporarily halted, thus avoiding conditions that cause genome rearrangements and mutations that might predispose to cancer or the accumulation of irreparable DNA damage and cause cellular aging.

Therefore, this system constitutes a very effective barrier to the uncontrolled cell growth that is typical of tumours.

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