Chromosomes

  • Article
    | Open Access

    DNA double-strand breaks (DSBs) induced by topoisomerase II (TOP2) are rejoined by TDP2-dependent non-homologous end-joining (NHEJ) but whether this promotes or suppresses translocations is not clear. Here the authors show that TDP2 suppresses chromosome translocations from DSBs introduced during gene transcription.

    • Fernando Gómez-Herreros
    • , Guido Zagnoli-Vieira
    •  & Keith W. Caldecott
  • Article
    | Open Access

    Precise chromosome segregation during mitosis requires coordination of stable chromosome bi-orientation with anaphase onset, however the underlying mechanism is not clear. Here the authors show that inner centromere localization of the chromosomal passenger complex maintains centromeric cohesion on bi-oriented chromosomes and allows mitotic checkpoint silencing.

    • Rutger C. C. Hengeveld
    • , Martijn J. M. Vromans
    •  & Susanne M. A. Lens
  • Article
    | Open Access

    POT1 and TTP1 are part of the shelterin complex that caps and stabilizes the ends of telomeres. Here the authors present a structural analysis of the human POT1-TTP1 complex, shedding light on how it assembles and how cancer-associated mutations impact its assembly and function.

    • Cory Rice
    • , Prashanth Krishna Shastrula
    •  & Emmanuel Skordalakes
  • Article
    | Open Access

    The three-dimensional architecture of genome-reduced bacteria is poorly understood. Here the authors combine Hi-C with super-resolution microscopy inMycoplasma pneumoniaeand provide evidence of how supercoiling and local organization influences gene regulation.

    • Marie Trussart
    • , Eva Yus
    •  & Luís Serrano
  • Article
    | Open Access

    Centromeres are chromosomal domains epigenetically specified by the presence of the CENP-A containing nucleosomes that control chromosome segregation. Here the authors show that α-amino trimethylation of CENP-A by the enzyme NRMT is required for centromere function, faithful chromosome segregation and cell survival.

    • Kizhakke M. Sathyan
    • , Daniele Fachinetti
    •  & Daniel R. Foltz
  • Article
    | Open Access

    The DNA damage response (DDR) involves site-specific small non-coding RNAs. Here the authors show that telomere dysfunction induces transcription of telomeric DNA damage response RNAs that are necessary for DDR activation, which can be specifically muted by antisense inhibitory oligonucleotides.

    • Francesca Rossiello
    • , Julio Aguado
    •  & Fabrizio d’Adda di Fagagna
  • Article
    | Open Access

    Structural Maintenance of Chromosomes (SMC) complexes maintain genome integrity by regulating the segregation of chromosomes. Here, Altet al. describe the structure of the heterodimeric Smc5/6-hinge from fission yeast and define functional features critical for Smc5/6’s cellular function.

    • Aaron Alt
    • , Hung Q. Dang
    •  & Antony W. Oliver
  • Article
    | Open Access

    The cohesin complex maintains genome integrity by ensuring correct sister-chromatid segregation during mitosis and meiosis. Here, Chaoet al. present a pseudo-atomic model of the full-length Scc2–Scc4 cohesin loader complex and reveal key Scc2 surfaces crucial for cohesin loading.

    • William C. H. Chao
    • , Yasuto Murayama
    •  & Martin R. Singleton
  • Article
    | Open Access

    Centromeres are centrochromatin domains with CENP-A and H3 nucleosomes carrying transcription-associated modifications. Here the authors target synthetic modules to the centromeres to show that transcription plus histone modifications are required for CENP-A assembly and centrochromatin maintenance.

    • Oscar Molina
    • , Giulia Vargiu
    •  & William C. Earnshaw
  • Article
    | Open Access

    The deposition of histone H3 variant CENP-A bound with histone H4 is a key feature designating the centromere region of a chromosome. Here the authors show acetylation on residues K5 and K12 in histone H4, mediated by the RbAp46/48-Hat1 complex, is required for deposition of CENP-A-H4 into centromeres.

    • Wei-Hao Shang
    • , Tetsuya Hori
    •  & Tatsuo Fukagawa
  • Article
    | Open Access

    The synaptonemal complex is a meiosis-specific proteinaceous structure that supports homologous chromosome pairs during meiosis. Here, the authors show that SIX6OS1 (of previously unknown function) is part of the synaptonemal complex central element and upon deletion in mice, causes defective chromosome synapsis and infertility.

    • Laura Gómez-H
    • , Natalia Felipe-Medina
    •  & Alberto M. Pendas
  • Article
    | Open Access

    Chromosomes bind microtubules (MT) from opposite spindle poles and the generated tension stabilizes kinetochore-MT attachments. Here the authors measure kinetochore forces by engineering two force sensors and propose that kinetochore fibers exert hundreds of pNs of force to bioriented kinetochores.

    • Anna A. Ye
    • , Stuart Cane
    •  & Thomas J. Maresca
  • Article
    | Open Access

    The telomeric long-non coding RNA, TERRA, has been proposed in the past to modulate different telomeric functions based on in vitrostudies. Here the authors show, using a genetic deletion approach, that TERRA is transcribed from the 20q subtelomere and that it is essential for telomere maintenance.

    • Juan José Montero
    • , Isabel López de Silanes
    •  & Maria A. Blasco
  • Article
    | Open Access

    Reactivation of the inactive X chromosome (Xi) has modelled epigenetic reprogramming in mouse. Here, by using cell fusion between human female fibroblasts and mouse embryonic stem cells, the authors show a complex hierarchy of epigenetic changes that are required to reactivate the genes on the human Xi chromosome.

    • Irene Cantone
    • , Hakan Bagci
    •  & Amanda G. Fisher
  • Article
    | Open Access

    The BubR1/Bub3 complex regulates chromosome segregation to enable proper kinetochore-microtubule interactions and is also required for the spindle assembly checkpoint. Here the authors show that two distinct pools of BubR1/Bub3 exist at kinetochores to support both known functions of BubR1/Bub3.

    • Gang Zhang
    • , Blanca Lopez Mendez
    •  & Jakob Nilsson
  • Review Article
    | Open Access

    Sex chromosome evolution begins when recombination between a homologous pair of chromosomes is halted. Here, Wright et al.review our current understanding of the causes and mechanisms of recombination suppression between incipient sex chromosomes and suggest future directions for the field.

    • Alison E. Wright
    • , Rebecca Dean
    •  & Judith E. Mank
  • Article
    | Open Access

    Telomere shortening has been linked to some aspects of organismal ageing. Here the authors create chimaeric mice that contain a mix of cells with normal or unnaturally long telomeres, and show chimaeric mice are protected from some forms of ageing-associated cellular damage and have accelerated wound-healing.

    • Elisa Varela
    • , Miguel A. Muñoz-Lorente
    •  & Maria A. Blasco
  • Article
    | Open Access

    Bacterial DNA primarily exists in a negatively supercoiled or under-wound state. Here, by mapping the supercoiling state, the authors show that there is a gradient of supercoiling across the bacterial chromosome with the terminus being more negatively supercoiled than the origin.

    • Avantika Lal
    • , Amlanjyoti Dhar
    •  & Sankar Adhya
  • Article
    | Open Access

    A chromosome is composed of structurally and functionally distinct domains. Here, Tashiro et al. report that the conserved centromeric protein Sgo2 localizes at the subtelomeres preferentially during G2phase and is essential for the formation of a highly condensed subtelomeric chromatin body “knob”.

    • Sanki Tashiro
    • , Tetsuya Handa
    •  & Junko Kanoh
  • Article
    | Open Access

    Drosophila telomeres are elongated by transposition of specialized retroelements rather than telomerase activity. Here, the authors show that Separase is enriched at Drosophila telomeres and loss of Sse, the gene encoding Separase, leads to telomere defects, suggesting a role for Separase in telomere protection.

    • Francesca Cipressa
    • , Patrizia Morciano
    •  & Giovanni Cenci
  • Article
    | Open Access

    The spindle assembly checkpoint relies on the accumulation of Mad1-Mad2 at kinetochores, but the mechanism of regulation is not known. Here Zhou et al. show that the centrosomal protein Cep57 interacts with the kinetochore proteins Mis12 and Mad1, and regulates the recruitment of Mad1/Mad2 to kinetochores.

    • Haining Zhou
    • , Tianning Wang
    •  & Jianguo Chen
  • Article
    | Open Access

    The X-chromosome linked long non-coding RNA, Xist, is a master regulator of the X inactivation. Here, the authors report that XistAR, an Xist anti-sense long non-coding RNA encoded within the mouse Xist gene and transcribed only from the inactive X chromosome, regulates Xistexpression.

    • Mrinal K. Sarkar
    • , Srimonta Gayen
    •  & Sundeep Kalantry
  • Article
    | Open Access

    Bub1 kinase phosphorylates histone H2A-T120 at the centromere to recruit shugoshin proteins and promote sister chromatid cohesion during mitosis. Here the authors show that Bub1 autophosphorylation on T589 influences Bub1 dynamics at the kinetochore and restricts H2A-T120 phosphorylation to centromeres.

    • Adeel Asghar
    • , Audrey Lajeunesse
    •  & Sabine Elowe
  • 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

    The Ndc80 complex acts as an interface between kinetochores and spindle microtubules, and is recruited to the kinetochore by several different proteins. Suzukiet al. use protein counting techniques and RNA interference to quantify the interaction stoichiometries within this intricate cellular structure.

    • Aussie Suzuki
    • , Benjamin L. Badger
    •  & Edward D. Salmon
  • 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
    | Open Access

    TD-60 (RCC2) structurally resembles a guanine nucleotide exchange factor (GEF), but its target GTPase was unknown. Here Papini et al.show that TD-60 is a GEF for RalA, and that RalA helps to regulate the chromosomal passenger complex and kinetochore–microtubule interactions in mitosis.

    • Diana Papini
    • , Lars Langemeyer
    •  & William C. Earnshaw
  • Article
    | Open Access

    Aneuploidy may be fatal for the embryo, hence predicting its occurrence is important for successfulin vitrofertilization. Here the authors monitor development of human preimplantation embryos in real-time and correlate the blastomere ploidy with cleavage dynamics and gene expression, identifying 12-transcript signature that determines ploidy.

    • Maria Vera-Rodriguez
    • , Shawn L. Chavez
    •  & Carlos Simon
  • Article
    | Open Access

    Binding and unbinding of transcription regulators at operator sites regulates gene expression. By single-molecule tracking of metal-sensing regulators, here the authors show that the unbinding kinetics depends on regulator concentration and chromosome condensation, and varies with their metal-binding states.

    • Tai-Yen Chen
    • , Ace George Santiago
    •  & Peng Chen
  • Article
    | Open Access

    The spatial organization of the genome within the nucleus impacts many processes. Here the authors combine oligo-based DNA FISH with single-molecule super-resolution microscopy to image single-copy genomic regions and, taking advantage of SNPs, distinguish allelic regions of homologous chromosomes.

    • Brian J. Beliveau
    • , Alistair N. Boettiger
    •  & Chao-ting Wu
  • Article |

    Borealin is a subunit of the chromosomal passenger complex that prevents premature mitosis before spindle assembly is complete. Bekier et al.show that Borealin mediates recruitment of this complex to both kinetochores and centromeres via distinct mechanisms, both of which depend on Borealin dimerization.

    • Michael E. Bekier
    • , Travis Mazur
    •  & William R. Taylor