Telomeres

  • Article
    | Open Access

    Telomeres in post-crisis cells are maintained by re-activated telomerase or by alternative lengthening of telomeres (ALT). Here, Seo et al. report a stable mode of ALT in worm where internal genomic regions generate a genomic reservoir ready to be incorporated into telomeres upon ALT activation.

    • Beomseok Seo
    • , Chuna Kim
    •  & Junho Lee
  • Article
    | Open Access

    DNA damage caused by ultraviolet irradiation is removed from the genome by nucleotide excision repair; however, it is unclear if this occurs at chromosome ends. Here the authors provide evidence indicating that telomeres are partially shielded from damage and that repair is fully functional.

    • Dhvani Parikh
    • , Elise Fouquerel
    •  & Patricia L. Opresko
  • Article
    | Open Access

    Erosion of telomeres eventually causes replicative senescence, but mechanisms underlying the variability and dynamics of the pathway are not known. Here, the authors examine senescence in single yeast cells with inactivated telomerase to reveal two mechanistically distinct routes to senescence.

    • Zhou Xu
    • , Emilie Fallet
    •  & Maria Teresa Teixeira
  • Article
    | Open Access

    G-quadruplexes formed by four guanine bases in a square planar arrangement in telomeres may prevent extension of this region by telomerase. Here, the authors show that telomerase can localize to and partially unwind and extend G-quadruplexes, suggesting an important biological role for G-quadruplexes.

    • Aaron L. Moye
    • , Karina C. Porter
    •  & Tracy M. Bryan
  • Article |

    In fission yeast, the telomerase RNA (TER) is produced through inhibition of the second step in splicing, resulting in spliceosomal cleavage. Here, the authors show that the inhibition of splicing is a conserved principle in fungal TER maturation that uses distinct molecular mechanisms across species.

    • Xiaodong Qi
    • , Dustin P. Rand
    •  & Julian J. -L. Chen
  • Article
    | Open Access

    In fission yeast, the telomerase RNA (TER) is produced through spliceosomal cleavage. Here, Kannan et al. find that spliceosome-generated 3′ ends also occurs in other fungal TERs using distinct molecular mechanisms, suggesting multiple origins for this type of TER maturation pathway.

    • Ram Kannan
    • , Rachel M. Helston
    •  & Peter Baumann
  • Article
    | Open Access

    The shortening of telomeres—a structure that protects chromosome ends—is associated with cellular aging. Here, Wood et al.present evidence that interaction between the telomere-binding protein TRF2 and lamin A/C facilitates the formation of interstitial t-loops and stabilizes telomeres.

    • Ashley M. Wood
    • , Jannie M. Rendtlew Danielsen
    •  & Steven T. Kosak
  • Article |

    Telomere uncapping in senescent cells is accompanied by loss of the TRF2 telomere capping factor and upregulation of the long noncoding RNA TERRA. Here the authors characterize the TERRA transcriptome and show that TERRA upregulation may promote SUV39H1 recruitment, H3K9 trimethylation and telomere end-to-end fusions.

    • Antonio Porro
    • , Sascha Feuerhahn
    •  & Joachim Lingner
  • Article
    | Open Access

    A subset of cancers maintains telomere length independently of telomerase by activating alternative lengthening of telomeres (ALT) pathways. Here the authors show that RNaseH1 modulates telomeric homologous recombination frequencies in ALT cells by regulating the levels of RNA–DNA hybrids between TERRA and telomeric DNA.

    • Rajika Arora
    • , Yongwoo Lee
    •  & Claus M. Azzalin
  • Article |

    The enzymes Sae2 and Sgs1 regulate telomere maintenance in yeast cells that are telomerase-positive or -negative, but how they do this is unclear. Here the authors show that Sae2 and Sgs1 facilitate telomere replication in telomerase-positive cells, but generate single-stranded DNA at eroded telomeres in telomerase-negative cells.

    • Julien Hardy
    • , Dmitri Churikov
    •  & Marie-Noëlle Simon
  • Article
    | Open Access

    Shortened telomeres and reduced mitochondrial biogenesis are cellular hallmarks of ageing. Here, Missios et al.show that old mice with telomere dysfunction have an increased energetic demand that cannot be met unless mice are fed a glucose-rich diet, which improves energy metabolism and extends lifespan.

    • Pavlos Missios
    • , Yuan Zhou
    •  & K. Lenhard Rudolph
  • Article
    | Open Access

    Telomeric RNAs (TERRAs) are known to be transcribed towards the telomere from subtelomeric regions, however, their precise genomic origins are unclear. Here López de Silanes et al.identify novel transcripts that originate from the subtelomeric region of mouse chromosome 18 and behave as bona fide TERRAs.

    • Isabel López de Silanes
    • , Osvaldo Graña
    •  & Maria A Blasco
  • Article |

    Telomerase reverse transcriptase extends the ends of linear chromosomes with the aid of an integral RNA subunit. Here, Parks and Stone characterize the translocation kinetics of telomerase identifying distinct steps important for the processivity of the enzyme.

    • Joseph W. Parks
    •  & Michael D. Stone
  • Article
    | Open Access

    Telomerase activity can be regulated by alternative splicing of its catalytic subunit TERT. Here, Wong et al. demonstrate that TERTsplicing is regulated via RNA:RNA pairing of repetitive intronic sequences with the pre-mRNA, thus revealing a new function for conserved elements embedded within introns.

    • Mandy S. Wong
    • , Jerry W. Shay
    •  & Woodring E. Wright
  • Article
    | Open Access

    Telomere shortening as a result of cell proliferation has been implicated in human ageing. Here, Daniali and colleagues show that telomere length and the rate of age-dependent shortening vary between adults but are similar within tissues of the same individual.

    • Lily Daniali
    • , Athanase Benetos
    •  & Abraham Aviv
  • Article |

    Chromatin is rendered silent by epigenetic marks when in proximity to telomeres, and, in yeast, this effect requires the histone-modifying enzyme Sir2. In this study, the human Sir2 family member SIRT6 is shown to modulate the telomere position effect in human cells.

    • Ruth I. Tennen
    • , Dennis J. Bua
    •  & Katrin F. Chua
  • Article |

    Recent work has revealed that the TTAGGG DNA repeats of telomeres are transcribed to form 'TERRA'. In this study, a set of RNA-binding proteins are shown to bind TERRA transcripts, altering the location of these transcripts at telomeres and regulating telomere abundance and length.

    • Isabel López de Silanes
    • , Martina Stagno d'Alcontres
    •  & Maria A Blasco