Chromosomes

  • 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

    Many cellular processes, including the cell division cycle, require concerted action of protein kinases and phosphatases. Here Lipinszki et al. present a crystal structure of the Drosophilaphosphoprotein phosphatase 4 subunit, Falafel, in complex with the centromeric protein CENP-C, and reveal a new recognition mode for this phosphatase.

    • Zoltan Lipinszki
    • , Stephane Lefevre
    •  & Marcin R. Przewloka
  • 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 |

    In bacteria, chromosomal architecture exhibits spatial and temporal fluctuations, which affect cellular functions. Here, Javer et al. use high-resolution tracking of chromosomal loci in E. colito uncover rare events of unusually large and fast movements, providing new insight into bacterial chromosome dynamics.

    • Avelino Javer
    • , Nathan J. Kuwada
    •  & Marco Cosentino Lagomarsino
  • 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 |

    The spatial and temporal organization of bacterial chromosomes is important for many cellular functions. Using high-precision measurements of fluorescently labelled chromosomal loci, Javer et al.demonstrate variation in the dynamics of different chromosomal sites, which may either be due to differential organization of the chromosome or spatial variation in molecular noise.

    • Avelino Javer
    • , Zhicheng Long
    •  & Marco Cosentino Lagomarsino
  • 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
    | Open Access

    There is debate about the structural organization of the yeast centromeric nucleosome and the role of the nonhistone protein Scm3 in its assembly. Dechassaet al.find that yeast centromeric nucleosomes organize DNA in a left-handed superhelix, and show that Scm3 is a specific nucleosome assembly factor.

    • Mekonnen Lemma Dechassa
    • , Katharina Wyns
    •  & Karolin Luger
  • Article |

    Matrilocal and patrilocal populations are predicted to have greater genetic diversity in mitochondrial DNA and the Y-chromosome, respectively. Here, no difference in the diversity of the Y-chromosome was found in two such groups, suggesting that local diversity was caused by male gene flow in expanding populations.

    • Ellen Dröfn Gunnarsdóttir
    • , Madhusudan R. Nandineni
    •  & Mark Stoneking
  • 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