Telomeres are transcribed into RNA


Telomeric Repeat–Containing RNA and RNA Surveillance Factors at Mammalian Chromosome Ends


Claus M. Azzalin ,Patrick Reichenback ,Lela Khoriauli , Elena Giulotto , Joachim Lingner 

Just came across this today in my trawl through science news. First found in a New Scientist post, and then I read the originating Science article. Turns out the authors have discovered that telomeres, long thought to be transcriptionally silent, do actually have "TElomeric Repeat–containing RNA (TERRA) ranging in size from ~100 bases up to at least 9 kilobases". Further, "TERRA molecules are transcribed from different telomeres and are composed of subtelomeric-derived RNA and UUAGGG repeats". Further, the authors have found evidence that these TERRA molecules interact with the telomeres. Their conclusions include "It is possible that TERRA promotes telomeric
heterochromatin assembly by mechanisms similar to the X chromosome inactivation in females, which is mediated by
the long noncoding Xist RNA (25), or to the RNAi-mediated heterochromatinization of the telomeric dh-homologous
region in fission yeast […] SMG proteins regulate TERRA at chromosome ends and UPF1 and EST1A physically interact with DNA polymerase δ and telomerase, respectively […] We speculate that the telomeric defects induced by
SMG-depletion could derive from loss of coordination between TERRA and key enzymatic activities that assure
telomere replication and length homeostasis."

I'm interested in anything having to do with cell longevity and immortality, not just for its relevance to cancerous cells, but also because the Centre I work for specializes in ageing research, and telomeres can be thought of as cell clocks, as the telomeres are shortened with every cell division (in healthy cells). It short paper worth reading, even if it is quite jargon-heavy.

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