Exonuclease1 (Exo1) deletion rescues crypt atrophy and survival of telomere dysfunctional mice

Introduction: The ends of linear chromosomes in yeast and mammalian nuclei are usually maintained either by recombination or telomerase. In the absence of both pathways cells enter senescence due to telomere shortening, which can affect aging and regeneration of tissues in vivo. Exo1, a 5–3 exonuclease, was found to play a decisive role in preventing senescent of budding yeast cells defective for both telomerase- and recombination-based mechanisms of telomere maintenance. One current hypothesis is that Exo1 processes dysfunctional telomeres thus inducing DNA-damage signalling. However, whether Exo1 plays a funct…