TRANSCRIPTOMIC SIGNATURES OF TELOMERASE-DEPENDENT AND -INDEPENDENT AGEING, IN THE ZEBRAFISH GUT AND BRAIN

Telomerase is best known for its role in the maintenance of telomere length and its implications for ageing and cancer. The mechanisms, kinetics and tissue-specificity underlying the protective or deleterious mechanisms of telomerase, however, remain largely unknown. Here, we sought to determine the telomerase-dependent and -independent transcriptomic changes with ageing, in the gut and brain, as examples of high and low proliferative tissues, respectively. We hypothesised this could shed light on common telomerase-dependent and -independent therapeutic targets aimed at preventing or ameliorating age-associated dysfunction in both tissues. For this, we used the zebrafish model which, similarly to humans, depends on telomerase for health- and lifespan. We performed whole tissue RNA sequencing of gut and brain, in naturally aged zebrafish alongside prematurely aged telomerase null mutants (tert-/-), throughout their lifespan. Our study highlights stem cell exhaustion as the first main hallmark of ageing to be de-regulated in WT zebrafish gut and brain. Towards the end of life, altered intercellular communication becomes the main hallmark of ageing de-regulated in both gut and brain, and this is accelerated in both tissues, in the absence of telomerase. Finally, we identify 7 key gene changes common between the gut and brain at the early stages of ageing, highlighting potential early intervention therapeutic targets for preventing age-associated dysfunction in both tissues. ### Competing Interest Statement The authors have declared no competing interest.