Premature aging in telomerase-deficient zebrafish

Abstract

SUMMARYThe study of telomere biology is crucial to the understanding of aging and cancer. In the pursuit of greater knowledge in the field of human telomere biology, the mouse has been used extensively as a model. However, there are fundamental differences between mouse and human cells. Therefore, additional models are required. In light of this, we have characterized telomerase-deficient zebrafish (Danio rerio) as the second vertebrate model for human telomerase-driven diseases. We found that telomerase-deficient zebrafish show p53-dependent premature aging and reduced lifespan in the first generation, as occurs in humans but not in mice, probably reflecting the similar telomere length in fish and humans. Among these aging symptoms, spinal curvature, liver and retina degeneration, and infertility were the most remarkable. Although the second-generation embryos died in early developmental stages, restoration of telomerase activity rescued telomere length and survival, indicating that telomerase dosage is crucial. Importantly, this model also reproduces the disease anticipation observed in humans with dyskeratosis congenita (DC). Thus, telomerase haploinsufficiency leads to anticipation phenomenon in longevity, which is related to telomere shortening and, specifically, with the proportion of short telomeres. Furthermore, p53 was induced by telomere attrition, leading to growth arrest and apoptosis. Importantly, genetic inhibition of p53 rescued the adverse effects of telomere loss, indicating that the molecular mechanisms induced by telomere shortening are conserved from fish to mammals. The partial rescue of telomere length and longevity by restoration of telomerase activity, together with the feasibility of the zebrafish for high-throughput chemical screening, both point to the usefulness of this model for the discovery of new drugs able to reactivate telomerase in individuals with DC.

A non-canonical function of telomerase RNA in the regulation of developmental myelopoiesis in zebrafish

“…Zebrafish (Danio rerio H., Cypriniformes, Cyprinidae) were obtained from the Zebrafish International Resource Center and mated, staged, raised and processed as described 54 . The tert mutant line (allele hu3430) was obtained from the Sanger Institute and has been previously described 28,55 . The casper mutant 56 and Tg(gata1::DsRed) 57 lines were previously described.…”

“…Next, we wondered whether the neutropenia of TR-deficient larvae was related to the lack of telomerase activity. To accomplish this, we performed a TSA staining assay at 30 hpf using a tert À / À zebrafish line, which lack telomerase activity 28 , and their tert þ / þ siblings. Although tertdeficient embryos showed normal number of neutrophils, the deficiency of TR resulted in the reduction of neutrophils in both wild type and tert-deficient fish to a similar level, demonstrating that the loss of neutrophils was independent of telomerase activity (Fig.…”

Telomere dynamics in a lizard with morph‐specific reproductive investment and self‐maintenance

“…Although telomerase knock-out organisms have been a successful tool for studying telomere dynamics (Anchelin et al, 2013;Mourkioti et al, 2013), the difficulty and cost of generating knock-outs limit our ability to investigate telomeres in non-model organisms. A compound that could be orally administered would be ideal for these purposes; however, our experiments showed no effect of TA-65 on lizard telomere length.…”

Modelling the p53/p66Shc Aging Pathway in the Shortest Living Vertebrate Nothobranchius Furzeri

“…Zebrafish embryos, with their fast development, transparency, easy handling and the potential to easily perform highly powerful statistical studies, are the ideal alternative to in vitro cell proliferation and senescence assays [36,37]. Although also zebrafish has been successfully used as a model in aging studies [38,39], we suggest to concentrate efforts in definitively establish N. furzeri as the new and widespread model for aging research to make the most of its potential.…”