1
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Bournaka S, Badra-Fajardo N, Arbi M, Taraviras S, Lygerou Z. The cell cycle revisited: DNA replication past S phase preserves genome integrity. Semin Cancer Biol 2024; 99:45-55. [PMID: 38346544 DOI: 10.1016/j.semcancer.2024.02.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2023] [Revised: 01/23/2024] [Accepted: 02/05/2024] [Indexed: 02/20/2024]
Abstract
Accurate and complete DNA duplication is critical for maintaining genome integrity. Multiple mechanisms regulate when and where DNA replication takes place, to ensure that the entire genome is duplicated once and only once per cell cycle. Although the bulk of the genome is copied during the S phase of the cell cycle, increasing evidence suggests that parts of the genome are replicated in G2 or mitosis, in a last attempt to secure that daughter cells inherit an accurate copy of parental DNA. Remaining unreplicated gaps may be passed down to progeny and replicated in the next G1 or S phase. These findings challenge the long-established view that genome duplication occurs strictly during the S phase, bridging DNA replication to DNA repair and providing novel therapeutic strategies for cancer treatment.
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Affiliation(s)
- Spyridoula Bournaka
- Department of General Biology, Medical School, University of Patras, Patras 26504, Greece
| | - Nibal Badra-Fajardo
- Department of General Biology, Medical School, University of Patras, Patras 26504, Greece
| | - Marina Arbi
- Department of General Biology, Medical School, University of Patras, Patras 26504, Greece
| | - Stavros Taraviras
- Department of Physiology, Medical School, University of Patras, Patras 26504, Greece
| | - Zoi Lygerou
- Department of General Biology, Medical School, University of Patras, Patras 26504, Greece.
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2
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Corda Y, Maestroni L, Luciano P, Najem MY, Géli V. Genome stability is guarded by yeast Rtt105 through multiple mechanisms. Genetics 2021; 217:6126811. [PMID: 33724421 DOI: 10.1093/genetics/iyaa035] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Accepted: 02/03/2021] [Indexed: 12/15/2022] Open
Abstract
Ty1 mobile DNA element is the most abundant and mutagenic retrotransposon present in the genome of the budding yeast Saccharomyces cerevisiae. Protein regulator of Ty1 transposition 105 (Rtt105) associates with large subunit of RPA and facilitates its loading onto a single-stranded DNA at replication forks. Here, we dissect the role of RTT105 in the maintenance of genome stability under normal conditions and upon various replication stresses through multiple genetic analyses. RTT105 is essential for viability in cells experiencing replication problems and in cells lacking functional S-phase checkpoints and DNA repair pathways involving homologous recombination. Our genetic analyses also indicate that RTT105 is crucial when cohesion is affected and is required for the establishment of normal heterochromatic structures. Moreover, RTT105 plays a role in telomere maintenance as its function is important for the telomere elongation phenotype resulting from the Est1 tethering to telomeres. Genetic analyses indicate that rtt105Δ affects the growth of several rfa1 mutants but does not aggravate their telomere length defects. Analysis of the phenotypes of rtt105Δ cells expressing NLS-Rfa1 fusion protein reveals that RTT105 safeguards genome stability through its role in RPA nuclear import but also by directly affecting RPA function in genome stability maintenance during replication.
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Affiliation(s)
- Yves Corda
- CNRS UMR7258, INSERM U1068, Aix-Marseille Université UM105, Institut Paoli-Calmettes, CRCM, Marseille, France.,Equipe Labellisée Ligue Nationale Contre le Cancer, Paris, France
| | - Laetitia Maestroni
- CNRS UMR7258, INSERM U1068, Aix-Marseille Université UM105, Institut Paoli-Calmettes, CRCM, Marseille, France.,Equipe Labellisée Ligue Nationale Contre le Cancer, Paris, France
| | - Pierre Luciano
- CNRS UMR7258, INSERM U1068, Aix-Marseille Université UM105, Institut Paoli-Calmettes, CRCM, Marseille, France.,Equipe Labellisée Ligue Nationale Contre le Cancer, Paris, France
| | - Maria Y Najem
- CNRS UMR7258, INSERM U1068, Aix-Marseille Université UM105, Institut Paoli-Calmettes, CRCM, Marseille, France.,Equipe Labellisée Ligue Nationale Contre le Cancer, Paris, France
| | - Vincent Géli
- CNRS UMR7258, INSERM U1068, Aix-Marseille Université UM105, Institut Paoli-Calmettes, CRCM, Marseille, France.,Equipe Labellisée Ligue Nationale Contre le Cancer, Paris, France
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3
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Hafner L, Lezaja A, Zhang X, Lemmens L, Shyian M, Albert B, Follonier C, Nunes JM, Lopes M, Shore D, Mattarocci S. Rif1 Binding and Control of Chromosome-Internal DNA Replication Origins Is Limited by Telomere Sequestration. Cell Rep 2019; 23:983-992. [PMID: 29694906 DOI: 10.1016/j.celrep.2018.03.113] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Revised: 01/12/2018] [Accepted: 03/24/2018] [Indexed: 12/31/2022] Open
Abstract
The Saccharomyces cerevisiae telomere-binding protein Rif1 plays an evolutionarily conserved role in control of DNA replication timing by promoting PP1-dependent dephosphorylation of replication initiation factors. However, ScRif1 binding outside of telomeres has never been detected, and it has thus been unclear whether Rif1 acts directly on the replication origins that it controls. Here, we show that, in unperturbed yeast cells, Rif1 primarily regulates late-replicating origins within 100 kb of a telomere. Using the chromatin endogenous cleavage ChEC-seq technique, we robustly detect Rif1 at late-replicating origins that we show are targets of its inhibitory action. Interestingly, abrogation of Rif1 telomere association by mutation of its Rap1-binding module increases Rif1 binding and origin inhibition elsewhere in the genome. Our results indicate that Rif1 inhibits replication initiation by interacting directly with origins and suggest that Rap1-dependent sequestration of Rif1 increases its effective concentration near telomeres, while limiting its action at chromosome-internal sites.
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Affiliation(s)
- Lukas Hafner
- Department of Molecular Biology, University of Geneva, Geneva, Switzerland; Institute of Genetics and Genomics of Geneva (iGE3), Geneva, Switzerland
| | - Aleksandra Lezaja
- Department of Molecular Biology, University of Geneva, Geneva, Switzerland; Institute of Genetics and Genomics of Geneva (iGE3), Geneva, Switzerland
| | - Xu Zhang
- Department of Molecular Biology, University of Geneva, Geneva, Switzerland; Institute of Genetics and Genomics of Geneva (iGE3), Geneva, Switzerland
| | - Laure Lemmens
- Department of Molecular Biology, University of Geneva, Geneva, Switzerland; Institute of Genetics and Genomics of Geneva (iGE3), Geneva, Switzerland
| | - Maksym Shyian
- Department of Molecular Biology, University of Geneva, Geneva, Switzerland; Institute of Genetics and Genomics of Geneva (iGE3), Geneva, Switzerland
| | - Benjamin Albert
- Department of Molecular Biology, University of Geneva, Geneva, Switzerland; Institute of Genetics and Genomics of Geneva (iGE3), Geneva, Switzerland
| | - Cindy Follonier
- Institute of Molecular Cancer Research, University of Zurich, Zurich 8057, Switzerland
| | - Jose Manuel Nunes
- Institute of Genetics and Genomics of Geneva (iGE3), Geneva, Switzerland; Department of Genetics and Evolution, University of Geneva, Geneva, Switzerland
| | - Massimo Lopes
- Institute of Molecular Cancer Research, University of Zurich, Zurich 8057, Switzerland
| | - David Shore
- Department of Molecular Biology, University of Geneva, Geneva, Switzerland; Institute of Genetics and Genomics of Geneva (iGE3), Geneva, Switzerland.
| | - Stefano Mattarocci
- Department of Molecular Biology, University of Geneva, Geneva, Switzerland; Institute of Genetics and Genomics of Geneva (iGE3), Geneva, Switzerland.
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4
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Towards the Mechanism of Yeast Telomere Dynamics. Trends Cell Biol 2019; 29:361-370. [PMID: 30765145 DOI: 10.1016/j.tcb.2019.01.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Revised: 01/04/2019] [Accepted: 01/11/2019] [Indexed: 12/31/2022]
Abstract
A mechanistic understanding of the yeast telomere requires an integrated understanding of telomere chromatin structure (telosomes), telomeric origins of replications, telomere length homeostasis, and telosome epigenetics. Recent molecular and genetic studies of the yeast telosomal components Rap1, Rif1, and Rif2, the Mre11 complex, and Tel1ATM promise to increase our insight into the coordination between these processes. Here, an intricate relationship is proposed between these multiple components that has resulted in increased appreciation of the multiple levels of telomere length control and their differentiation from double-strand repair. The mre11A470 motif (A470-A482) alleles have also opened new avenues to the exploration of telosome structure and function.
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5
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Aksenova AY, Mirkin SM. At the Beginning of the End and in the Middle of the Beginning: Structure and Maintenance of Telomeric DNA Repeats and Interstitial Telomeric Sequences. Genes (Basel) 2019; 10:genes10020118. [PMID: 30764567 PMCID: PMC6410037 DOI: 10.3390/genes10020118] [Citation(s) in RCA: 58] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2019] [Revised: 01/30/2019] [Accepted: 01/30/2019] [Indexed: 02/07/2023] Open
Abstract
Tandem DNA repeats derived from the ancestral (TTAGGG)n run were first detected at chromosome ends of the majority of living organisms, hence the name telomeric DNA repeats. Subsequently, it has become clear that telomeric motifs are also present within chromosomes, and they were suitably called interstitial telomeric sequences (ITSs). It is well known that telomeric DNA repeats play a key role in chromosome stability, preventing end-to-end fusions and precluding the recurrent DNA loss during replication. Recent data suggest that ITSs are also important genomic elements as they confer its karyotype plasticity. In fact, ITSs appeared to be among the most unstable microsatellite sequences as they are highly length polymorphic and can trigger chromosomal fragility and gross chromosomal rearrangements. Importantly, mechanisms responsible for their instability appear to be similar to the mechanisms that maintain the length of genuine telomeres. This review compares the mechanisms of maintenance and dynamic properties of telomeric repeats and ITSs and discusses the implications of these dynamics on genome stability.
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Affiliation(s)
- Anna Y Aksenova
- Laboratory of Amyloid Biology, St. Petersburg State University, 199034 St. Petersburg, Russia.
| | - Sergei M Mirkin
- Department of Biology, Tufts University, Medford, MA 02421, USA.
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6
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ChECing out Rif1 action in freely cycling cells. Curr Genet 2018; 65:429-434. [PMID: 30456647 DOI: 10.1007/s00294-018-0902-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Revised: 10/29/2018] [Accepted: 11/10/2018] [Indexed: 10/27/2022]
Abstract
In buddying yeast, like all eukaryotes examined so far, DNA replication is under temporal control, such that some origins fire early and some late during S phase. This replication timing program is established in G1 phase, where chromatin states are thought to prevent binding of key-limiting initiation factors at late-firing origins. Although many factors are involved in replication initiation, a new player, Rif1, has recently entered the scene, with a spate of papers revealing a global role for the protein in the control of replication initiation timing from yeasts to humans. Since budding yeast Rif1 was known to bind only to telomeric and silent mating loci regions, it remained controversial whether Rif1 acts directly at replication origins or instead influences origin activity indirectly. In this perspective, we discuss our recent finding that Rif1 binds directly to the replication origins that it controls. In this study, we also found that Rif1's regulatory activity at origins is best revealed by an assay (sort-seq) that measures replication in unperturbed, freely cycling cultures, as opposed to commonly used protocols in which cells are first blocked in the G1 phase of the cell cycle by mating pheromone, then released into a synchronous S phase. Finally, we discuss how the sequestration of Rif1 at telomeres, through an interaction with the arrays of Rap1 molecules bound there, plays an important role in limiting Rif1's action primarily to telomere-proximal replication origins.
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7
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Fontana GA, Reinert JK, Thomä NH, Rass U. Shepherding DNA ends: Rif1 protects telomeres and chromosome breaks. MICROBIAL CELL 2018; 5:327-343. [PMID: 29992129 PMCID: PMC6035837 DOI: 10.15698/mic2018.07.639] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Cells have evolved conserved mechanisms to protect DNA ends, such as those at the termini of linear chromosomes, or those at DNA double-strand breaks (DSBs). In eukaryotes, DNA ends at chromosomal termini are packaged into proteinaceous structures called telomeres. Telomeres protect chromosome ends from erosion, inadvertent activation of the cellular DNA damage response (DDR), and telomere fusion. In contrast, cells must respond to damage-induced DNA ends at DSBs by harnessing the DDR to restore chromosome integrity, avoiding genome instability and disease. Intriguingly, Rif1 (Rap1-interacting factor 1) has been implicated in telomere homeostasis as well as DSB repair. The protein was first identified in Saccharomyces cerevisiae as being part of the proteinaceous telosome. In mammals, RIF1 is not associated with intact telomeres, but was found at chromosome breaks, where RIF1 has emerged as a key mediator of pathway choice between the two evolutionary conserved DSB repair pathways of non-homologous end-joining (NHEJ) and homologous recombination (HR). While this functional dichotomy has long been a puzzle, recent findings link yeast Rif1 not only to telomeres, but also to DSB repair, and mechanistic parallels likely exist. In this review, we will provide an overview of the actions of Rif1 at DNA ends and explore how exclusion of end-processing factors might be the underlying principle allowing Rif1 to fulfill diverse biological roles at telomeres and chromosome breaks.
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Affiliation(s)
- Gabriele A Fontana
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, CH-4058 Basel, Switzerland
| | - Julia K Reinert
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, CH-4058 Basel, Switzerland.,University of Basel, Petersplatz 10, CH-4003 Basel, Switzerland
| | - Nicolas H Thomä
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, CH-4058 Basel, Switzerland
| | - Ulrich Rass
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, CH-4058 Basel, Switzerland
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8
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Kedziora S, Gali VK, Wilson RHC, Clark KRM, Nieduszynski CA, Hiraga SI, Donaldson AD. Rif1 acts through Protein Phosphatase 1 but independent of replication timing to suppress telomere extension in budding yeast. Nucleic Acids Res 2018; 46:3993-4003. [PMID: 29529242 PMCID: PMC5934629 DOI: 10.1093/nar/gky132] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2017] [Revised: 02/09/2018] [Accepted: 02/23/2018] [Indexed: 12/24/2022] Open
Abstract
The Rif1 protein negatively regulates telomeric TG repeat length in the budding yeast Saccharomyces cerevisiae, but how it prevents telomere over-extension is unknown. Rif1 was recently shown to control DNA replication by acting as a Protein Phosphatase 1 (PP1)-targeting subunit. Therefore, we investigated whether Rif1 controls telomere length by targeting PP1 activity. We find that a Rif1 mutant defective for PP1 interaction causes a long-telomere phenotype, similar to that of rif1Δ cells. Tethering PP1 at a specific telomere partially substitutes for Rif1 in limiting TG repeat length, confirming the importance of PP1 in telomere length control. Ablating Rif1-PP1 interaction is known to cause precocious activation of telomere-proximal replication origins and aberrantly early telomere replication. However, we find that Rif1 still limits telomere length even if late replication is forced through deletion of nearby replication origins, indicating that Rif1 can control telomere length independent of replication timing. Moreover we find that, even at a de novo telomere created after DNA synthesis during a mitotic block, Rif1-PP1 interaction is required to suppress telomere lengthening and prevent inappropriate recruitment of Tel1 kinase. Overall, our results show that Rif1 controls telomere length by recruiting PP1 to directly suppress telomerase-mediated TG repeat lengthening.
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Affiliation(s)
- Sylwia Kedziora
- Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, Scotland, UK
| | - Vamsi K Gali
- Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, Scotland, UK
| | - Rosemary HC Wilson
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
| | - Kate RM Clark
- Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, Scotland, UK
| | - Conrad A Nieduszynski
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
| | - Shin-ichiro Hiraga
- Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, Scotland, UK
| | - Anne D Donaldson
- Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, Scotland, UK
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9
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Simoneau A, Ricard É, Wurtele H. An interplay between multiple sirtuins promotes completion of DNA replication in cells with short telomeres. PLoS Genet 2018; 14:e1007356. [PMID: 29659581 PMCID: PMC5919697 DOI: 10.1371/journal.pgen.1007356] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2017] [Revised: 04/26/2018] [Accepted: 04/09/2018] [Indexed: 01/08/2023] Open
Abstract
The evolutionarily-conserved sirtuin family of histone deacetylases regulates a multitude of DNA-associated processes. A recent genome-wide screen conducted in the yeast Saccharomyces cerevisiae identified Yku70/80, which regulate nonhomologous end-joining (NHEJ) and telomere structure, as being essential for cell proliferation in the presence of the pan-sirtuin inhibitor nicotinamide (NAM). Here, we show that sirtuin-dependent deacetylation of both histone H3 lysine 56 and H4 lysine 16 promotes growth of yku70Δ and yku80Δ cells, and that the NAM sensitivity of these mutants is not caused by defects in DNA double-strand break repair by NHEJ, but rather by their inability to maintain normal telomere length. Indeed, our results indicate that in the absence of sirtuin activity, cells with abnormally short telomeres, e.g., yku70/80Δ or est1/2Δ mutants, present striking defects in S phase progression. Our data further suggest that early firing of replication origins at short telomeres compromises the cellular response to NAM- and genotoxin-induced replicative stress. Finally, we show that reducing H4K16ac in yku70Δ cells limits activation of the DNA damage checkpoint kinase Rad53 in response to replicative stress, which promotes usage of translesion synthesis and S phase progression. Our results reveal a novel interplay between sirtuin-mediated regulation of chromatin structure and telomere-regulating factors in promoting timely completion of S phase upon replicative stress.
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Affiliation(s)
- Antoine Simoneau
- Centre de recherche de l’Hôpital Maisonneuve-Rosemont, boulevard de l’Assomption, Montréal, Canada
- Programme de Biologie Moléculaire, Université de Montréal, Montréal, Canada
| | - Étienne Ricard
- Centre de recherche de l’Hôpital Maisonneuve-Rosemont, boulevard de l’Assomption, Montréal, Canada
- Programme de Biologie Moléculaire, Université de Montréal, Montréal, Canada
| | - Hugo Wurtele
- Centre de recherche de l’Hôpital Maisonneuve-Rosemont, boulevard de l’Assomption, Montréal, Canada
- Département de Médecine, Université de Montréal, Montréal, Canada
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10
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Chen H, Xue J, Churikov D, Hass EP, Shi S, Lemon LD, Luciano P, Bertuch AA, Zappulla DC, Géli V, Wu J, Lei M. Structural Insights into Yeast Telomerase Recruitment to Telomeres. Cell 2017; 172:331-343.e13. [PMID: 29290466 DOI: 10.1016/j.cell.2017.12.008] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Revised: 09/27/2017] [Accepted: 12/04/2017] [Indexed: 10/18/2022]
Abstract
Telomerase maintains chromosome ends from humans to yeasts. Recruitment of yeast telomerase to telomeres occurs through its Ku and Est1 subunits via independent interactions with telomerase RNA (TLC1) and telomeric proteins Sir4 and Cdc13, respectively. However, the structures of the molecules comprising these telomerase-recruiting pathways remain unknown. Here, we report crystal structures of the Ku heterodimer and Est1 complexed with their key binding partners. Two major findings are as follows: (1) Ku specifically binds to telomerase RNA in a distinct, yet related, manner to how it binds DNA; and (2) Est1 employs two separate pockets to bind distinct motifs of Cdc13. The N-terminal Cdc13-binding site of Est1 cooperates with the TLC1-Ku-Sir4 pathway for telomerase recruitment, whereas the C-terminal interface is dispensable for binding Est1 in vitro yet is nevertheless essential for telomere maintenance in vivo. Overall, our results integrate previous models and provide fundamentally valuable structural information regarding telomere biology.
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Affiliation(s)
- Hongwen Chen
- State Key Laboratory of Molecular Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 201210 Shanghai, China
| | - Jing Xue
- State Key Laboratory of Molecular Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 201210 Shanghai, China
| | - Dmitri Churikov
- Marseille Cancer Research Center (CRCM), U1068 INSERM, UMR7258 CNRS, Aix Marseille University, Institut Paoli-Calmettes (Equipe labellisée Ligue), 13009 Marseille, France
| | - Evan P Hass
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Shaohua Shi
- State Key Laboratory of Molecular Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 201210 Shanghai, China
| | - Laramie D Lemon
- Department of Pediatrics, Baylor College of Medicine, One Baylor Plaza, BCM225, Houston, TX 77030, USA
| | - Pierre Luciano
- Marseille Cancer Research Center (CRCM), U1068 INSERM, UMR7258 CNRS, Aix Marseille University, Institut Paoli-Calmettes (Equipe labellisée Ligue), 13009 Marseille, France
| | - Alison A Bertuch
- Department of Pediatrics, Baylor College of Medicine, One Baylor Plaza, BCM225, Houston, TX 77030, USA
| | - David C Zappulla
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Vincent Géli
- Marseille Cancer Research Center (CRCM), U1068 INSERM, UMR7258 CNRS, Aix Marseille University, Institut Paoli-Calmettes (Equipe labellisée Ligue), 13009 Marseille, France
| | - Jian Wu
- State Key Laboratory of Molecular Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 201210 Shanghai, China.
| | - Ming Lei
- Shanghai Institute of Precision Medicine, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200125, China; Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Shanghai Jiao Tong University School of Medicine, 200025 Shanghai, China.
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11
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Graf M, Bonetti D, Lockhart A, Serhal K, Kellner V, Maicher A, Jolivet P, Teixeira MT, Luke B. Telomere Length Determines TERRA and R-Loop Regulation through the Cell Cycle. Cell 2017; 170:72-85.e14. [DOI: 10.1016/j.cell.2017.06.006] [Citation(s) in RCA: 128] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2017] [Revised: 04/21/2017] [Accepted: 06/06/2017] [Indexed: 10/19/2022]
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12
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Abstract
The accurate and complete replication of genomic DNA is essential for all life. In eukaryotic cells, the assembly of the multi-enzyme replisomes that perform replication is divided into stages that occur at distinct phases of the cell cycle. Replicative DNA helicases are loaded around origins of DNA replication exclusively during G1 phase. The loaded helicases are then activated during S phase and associate with the replicative DNA polymerases and other accessory proteins. The function of the resulting replisomes is monitored by checkpoint proteins that protect arrested replisomes and inhibit new initiation when replication is inhibited. The replisome also coordinates nucleosome disassembly, assembly, and the establishment of sister chromatid cohesion. Finally, when two replisomes converge they are disassembled. Studies in Saccharomyces cerevisiae have led the way in our understanding of these processes. Here, we review our increasingly molecular understanding of these events and their regulation.
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13
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Abstract
In this Hypothesis, Greider describes a new model for telomere length regulation, which links DNA replication and telomere elongation. Telomere length is regulated around an equilibrium set point. Telomeres shorten during replication and are lengthened by telomerase. Disruption of the length equilibrium leads to disease; thus, it is important to understand the mechanisms that regulate length at the molecular level. The prevailing protein-counting model for regulating telomerase access to elongate the telomere does not explain accumulating evidence of a role of DNA replication in telomere length regulation. Here I present an alternative model: the replication fork model that can explain how passage of a replication fork and regulation of origin firing affect telomere length.
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Affiliation(s)
- Carol W Greider
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA; Department of Biology, Johns Hopkins University, Baltimore, Maryland 21218, USA
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14
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Maestroni L, Matmati S, Coulon S. Solving the Telomere Replication Problem. Genes (Basel) 2017; 8:genes8020055. [PMID: 28146113 PMCID: PMC5333044 DOI: 10.3390/genes8020055] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2016] [Accepted: 01/23/2017] [Indexed: 12/12/2022] Open
Abstract
Telomeres are complex nucleoprotein structures that protect the extremities of linear chromosomes. Telomere replication is a major challenge because many obstacles to the progression of the replication fork are concentrated at the ends of the chromosomes. This is known as the telomere replication problem. In this article, different and new aspects of telomere replication, that can threaten the integrity of telomeres, will be reviewed. In particular, we will focus on the functions of shelterin and the replisome for the preservation of telomere integrity.
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Affiliation(s)
- Laetitia Maestroni
- Aix Marseille Univ, CNRS, INSERM, Institut Paoli-Calmettes, CRCM, Equipe labélisée Ligue Contre le Cancer, 13273 Marseille, France.
| | - Samah Matmati
- Aix Marseille Univ, CNRS, INSERM, Institut Paoli-Calmettes, CRCM, Equipe labélisée Ligue Contre le Cancer, 13273 Marseille, France.
| | - Stéphane Coulon
- Aix Marseille Univ, CNRS, INSERM, Institut Paoli-Calmettes, CRCM, Equipe labélisée Ligue Contre le Cancer, 13273 Marseille, France.
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15
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Rif1-Dependent Regulation of Genome Replication in Mammals. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 1042:259-272. [DOI: 10.1007/978-981-10-6955-0_12] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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16
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Shyian M, Mattarocci S, Albert B, Hafner L, Lezaja A, Costanzo M, Boone C, Shore D. Budding Yeast Rif1 Controls Genome Integrity by Inhibiting rDNA Replication. PLoS Genet 2016; 12:e1006414. [PMID: 27820830 PMCID: PMC5098799 DOI: 10.1371/journal.pgen.1006414] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2016] [Accepted: 10/10/2016] [Indexed: 12/27/2022] Open
Abstract
The Rif1 protein is a negative regulator of DNA replication initiation in eukaryotes. Here we show that budding yeast Rif1 inhibits DNA replication initiation at the rDNA locus. Absence of Rif1, or disruption of its interaction with PP1/Glc7 phosphatase, leads to more intensive rDNA replication. The effect of Rif1-Glc7 on rDNA replication is similar to that of the Sir2 deacetylase, and the two would appear to act in the same pathway, since the rif1Δ sir2Δ double mutant shows no further increase in rDNA replication. Loss of Rif1-Glc7 activity is also accompanied by an increase in rDNA repeat instability that again is not additive with the effect of sir2Δ. We find, in addition, that the viability of rif1Δ cells is severely compromised in combination with disruption of the MRX or Ctf4-Mms22 complexes, both of which are implicated in stabilization of stalled replication forks. Significantly, we show that removal of the rDNA replication fork barrier (RFB) protein Fob1, alleviation of replisome pausing by deletion of the Tof1/Csm3 complex, or a large deletion of the rDNA repeat array all rescue this synthetic growth defect of rif1Δ cells lacking in addition either MRX or Ctf4-Mms22 activity. These data suggest that the repression of origin activation by Rif1-Glc7 is important to avoid the deleterious accumulation of stalled replication forks at the rDNA RFB, which become lethal when fork stability is compromised. Finally, we show that Rif1-Glc7, unlike Sir2, has an important effect on origin firing outside of the rDNA locus that serves to prevent activation of the DNA replication checkpoint. Our results thus provide insights into a mechanism of replication control within a large repetitive chromosomal domain and its importance for the maintenance of genome stability. These findings may have important implications for metazoans, where large blocks of repetitive sequences are much more common.
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Affiliation(s)
- Maksym Shyian
- Department of Molecular Biology, University of Geneva, Geneva, Switzerland
- Institute of Genetics and Genomics in Geneva (iGE3), Geneva, Switzerland
| | - Stefano Mattarocci
- Department of Molecular Biology, University of Geneva, Geneva, Switzerland
- Institute of Genetics and Genomics in Geneva (iGE3), Geneva, Switzerland
| | - Benjamin Albert
- Department of Molecular Biology, University of Geneva, Geneva, Switzerland
- Institute of Genetics and Genomics in Geneva (iGE3), Geneva, Switzerland
| | - Lukas Hafner
- Department of Molecular Biology, University of Geneva, Geneva, Switzerland
- Institute of Genetics and Genomics in Geneva (iGE3), Geneva, Switzerland
| | - Aleksandra Lezaja
- Department of Molecular Biology, University of Geneva, Geneva, Switzerland
- Institute of Genetics and Genomics in Geneva (iGE3), Geneva, Switzerland
| | - Michael Costanzo
- University of Toronto, Donnelly Centre, Toronto, Ontario, Canada
| | - Charlie Boone
- University of Toronto, Donnelly Centre, Toronto, Ontario, Canada
| | - David Shore
- Department of Molecular Biology, University of Geneva, Geneva, Switzerland
- Institute of Genetics and Genomics in Geneva (iGE3), Geneva, Switzerland
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17
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Piqueret-Stephan L, Ricoul M, Hempel WM, Sabatier L. Replication Timing of Human Telomeres is Conserved during Immortalization and Influenced by Respective Subtelomeres. Sci Rep 2016; 6:32510. [PMID: 27587191 PMCID: PMC5009427 DOI: 10.1038/srep32510] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2016] [Accepted: 08/05/2016] [Indexed: 12/16/2022] Open
Abstract
Telomeres are specific structures that protect chromosome ends and act as a biological clock, preventing normal cells from replicating indefinitely. Mammalian telomeres are replicated throughout S-phase in a predetermined order. However, the mechanism of this regulation is still unknown. We wished to investigate this phenomenon under physiological conditions in a changing environment, such as the immortalization process to better understand the mechanism for its control. We thus examined the timing of human telomere replication in normal and SV40 immortalized cells, which are cytogenetically very similar to cancer cells. We found that the timing of telomere replication was globally conserved under different conditions during the immortalization process. The timing of telomere replication was conserved despite changes in telomere length due to endogenous telomerase reactivation, in duplicated homologous chromosomes, and in rearranged chromosomes. Importantly, translocated telomeres, possessing their initial subtelomere, retained the replication timing of their homolog, independently of the proportion of the translocated arm, even when the remaining flanking DNA is restricted to its subtelomere, the closest chromosome-specific sequences (inferior to 500 kb). Our observations support the notion that subtelomere regions strongly influence the replication timing of the associated telomere.
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Affiliation(s)
- Laure Piqueret-Stephan
- PROCyTOX Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA), Fontenay-aux-Roses and Université Paris-Saclay, France
| | - Michelle Ricoul
- PROCyTOX Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA), Fontenay-aux-Roses and Université Paris-Saclay, France
| | - William M Hempel
- PROCyTOX Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA), Fontenay-aux-Roses and Université Paris-Saclay, France
| | - Laure Sabatier
- PROCyTOX Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA), Fontenay-aux-Roses and Université Paris-Saclay, France
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18
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Duan YM, Zhou BO, Peng J, Tong XJ, Zhang QD, Zhou JQ. Molecular dynamics of de novo telomere heterochromatin formation in budding yeast. J Genet Genomics 2016; 43:451-65. [DOI: 10.1016/j.jgg.2016.03.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2015] [Revised: 03/09/2016] [Accepted: 03/17/2016] [Indexed: 11/26/2022]
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19
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Mattarocci S, Hafner L, Lezaja A, Shyian M, Shore D. Rif1: A Conserved Regulator of DNA Replication and Repair Hijacked by Telomeres in Yeasts. Front Genet 2016; 7:45. [PMID: 27066066 PMCID: PMC4811881 DOI: 10.3389/fgene.2016.00045] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Accepted: 03/14/2016] [Indexed: 12/12/2022] Open
Abstract
Rap1-interacting factor 1 (Rif1) was originally identified in the budding yeast Saccharomyces cerevisiae as a telomere-binding protein that negatively regulates telomerase-mediated telomere elongation. Although this function is conserved in the distantly related fission yeast Schizosaccharomyces pombe, recent studies, both in yeasts and in metazoans, reveal that Rif1 also functions more globally, both in the temporal control of DNA replication and in DNA repair. Rif1 proteins are large and characterized by N-terminal HEAT repeats, predicted to form an elongated alpha-helical structure. In addition, all Rif1 homologs contain two short motifs, abbreviated RVxF/SILK, that are implicated in recruitment of the PP1 (yeast Glc7) phosphatase. In yeasts the RVxF/SILK domains have been shown to play a role in control of DNA replication initiation, at least in part through targeted de-phosphorylation of proteins in the pre-Replication Complex. In human cells Rif1 is recruited to DNA double-strand breaks through an interaction with 53BP1 where it counteracts DNA resection, thus promoting repair by non-homologous end-joining. This function requires the N-terminal HEAT repeat-containing domain. Interestingly, this domain is also implicated in DNA end protection at un-capped telomeres in yeast. We conclude by discussing the deployment of Rif1 at telomeres in yeasts from both an evolutionary perspective and in light of its recently discovered global functions.
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Affiliation(s)
- Stefano Mattarocci
- Department of Molecular Biology and Institute for Genetics and Genomics in Geneva, University of Geneva Geneva, Switzerland
| | - Lukas Hafner
- Department of Molecular Biology and Institute for Genetics and Genomics in Geneva, University of Geneva Geneva, Switzerland
| | - Aleksandra Lezaja
- Department of Molecular Biology and Institute for Genetics and Genomics in Geneva, University of Geneva Geneva, Switzerland
| | - Maksym Shyian
- Department of Molecular Biology and Institute for Genetics and Genomics in Geneva, University of Geneva Geneva, Switzerland
| | - David Shore
- Department of Molecular Biology and Institute for Genetics and Genomics in Geneva, University of Geneva Geneva, Switzerland
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20
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Shugoshin forms a specialized chromatin domain at subtelomeres that regulates transcription and replication timing. Nat Commun 2016; 7:10393. [PMID: 26804021 PMCID: PMC4737732 DOI: 10.1038/ncomms10393] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2015] [Accepted: 12/07/2015] [Indexed: 01/11/2023] Open
Abstract
A chromosome is composed of structurally and functionally distinct domains. However, the molecular mechanisms underlying the formation of chromatin structure and the function of subtelomeres, the telomere-adjacent regions, remain obscure. Here we report the roles of the conserved centromeric protein Shugoshin 2 (Sgo2) in defining chromatin structure and functions of the subtelomeres in the fission yeast Schizosaccharomyces pombe. We show that Sgo2 localizes at the subtelomeres preferentially during G2 phase and is essential for the formation of a highly condensed subtelomeric chromatin body 'knob'. Furthermore, the absence of Sgo2 leads to the derepression of the subtelomeric genes and premature DNA replication at the subtelomeric late origins. Thus, the subtelomeric specialized chromatin domain organized by Sgo2 represses both transcription and replication to ensure proper gene expression and replication timing.
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21
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Foti R, Gnan S, Cornacchia D, Dileep V, Bulut-Karslioglu A, Diehl S, Buness A, Klein FA, Huber W, Johnstone E, Loos R, Bertone P, Gilbert DM, Manke T, Jenuwein T, Buonomo SCB. Nuclear Architecture Organized by Rif1 Underpins the Replication-Timing Program. Mol Cell 2016; 61:260-73. [PMID: 26725008 PMCID: PMC4724237 DOI: 10.1016/j.molcel.2015.12.001] [Citation(s) in RCA: 125] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2015] [Revised: 07/22/2015] [Accepted: 11/13/2015] [Indexed: 02/08/2023]
Abstract
DNA replication is temporally and spatially organized in all eukaryotes, yet the molecular control and biological function of the replication-timing program are unclear. Rif1 is required for normal genome-wide regulation of replication timing, but its molecular function is poorly understood. Here we show that in mouse embryonic stem cells, Rif1 coats late-replicating domains and, with Lamin B1, identifies most of the late-replicating genome. Rif1 is an essential determinant of replication timing of non-Lamin B1-bound late domains. We further demonstrate that Rif1 defines and restricts the interactions between replication-timing domains during the G1 phase, thereby revealing a function of Rif1 as organizer of nuclear architecture. Rif1 loss affects both number and replication-timing specificity of the interactions between replication-timing domains. In addition, during the S phase, Rif1 ensures that replication of interacting domains is temporally coordinated. In summary, our study identifies Rif1 as the molecular link between nuclear architecture and replication-timing establishment in mammals.
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Affiliation(s)
- Rossana Foti
- Mouse Biology Unit, EMBL Monterotondo, Via Ramarini 32, 00015 Monterotondo, Italy
| | - Stefano Gnan
- Mouse Biology Unit, EMBL Monterotondo, Via Ramarini 32, 00015 Monterotondo, Italy
| | - Daniela Cornacchia
- Mouse Biology Unit, EMBL Monterotondo, Via Ramarini 32, 00015 Monterotondo, Italy
| | - Vishnu Dileep
- Department of Biological Science, Florida State University, Tallahassee, FL 32306, USA
| | - Aydan Bulut-Karslioglu
- Max Planck Institute of Immunbiology and Epigenetics, Stubeweg 51, 79108 Freiburg, Germany
| | - Sarah Diehl
- Max Planck Institute of Immunbiology and Epigenetics, Stubeweg 51, 79108 Freiburg, Germany
| | - Andreas Buness
- Mouse Biology Unit, EMBL Monterotondo, Via Ramarini 32, 00015 Monterotondo, Italy
| | - Felix A Klein
- Genome Biology Unit, European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany
| | - Wolfgang Huber
- Genome Biology Unit, European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany
| | - Ewan Johnstone
- European Molecular Biology Laboratory, European Bioinformatics Institute, Wellcome Trust Genome Campus, Cambridge CB10 1SD, UK
| | - Remco Loos
- European Molecular Biology Laboratory, European Bioinformatics Institute, Wellcome Trust Genome Campus, Cambridge CB10 1SD, UK
| | - Paul Bertone
- European Molecular Biology Laboratory, European Bioinformatics Institute, Wellcome Trust Genome Campus, Cambridge CB10 1SD, UK; Genome Biology and Developmental Biology Units, European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany; Wellcome Trust-Medical Research Council Stem Cell Institute, University of Cambridge, Tennis Court Road, Cambridge CB2 1QR, UK
| | - David M Gilbert
- Department of Biological Science, Florida State University, Tallahassee, FL 32306, USA
| | - Thomas Manke
- Max Planck Institute of Immunbiology and Epigenetics, Stubeweg 51, 79108 Freiburg, Germany
| | - Thomas Jenuwein
- Max Planck Institute of Immunbiology and Epigenetics, Stubeweg 51, 79108 Freiburg, Germany
| | - Sara C B Buonomo
- Mouse Biology Unit, EMBL Monterotondo, Via Ramarini 32, 00015 Monterotondo, Italy.
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22
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Kwapisz M, Ruault M, van Dijk E, Gourvennec S, Descrimes M, Taddei A, Morillon A. Expression of Subtelomeric lncRNAs Links Telomeres Dynamics to RNA Decay in S. cerevisiae. Noncoding RNA 2015; 1:94-126. [PMID: 29861418 PMCID: PMC5932542 DOI: 10.3390/ncrna1020094] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2015] [Revised: 06/17/2015] [Accepted: 06/17/2015] [Indexed: 11/24/2022] Open
Abstract
Long non-coding RNAs (lncRNAs) have been shown to regulate gene expression, chromatin domains and chromosome stability in eukaryotic cells. Recent observations have reported the existence of telomeric repeats containing long ncRNAs – TERRA in mammalian and yeast cells. However, their functions remain poorly characterized. Here, we report the existence in S. cerevisiae of several lncRNAs within Y′ subtelomeric regions. We have called them subTERRA. These belong to Cryptic Unstable Transcripts (CUTs) and Xrn1p-sensitive Unstable Transcripts (XUTs) family. subTERRA transcription, carried out mainly by RNAPII, is initiated within the subtelomeric Y’ element and occurs in both directions, towards telomeres as well as centromeres. We show that subTERRA are distinct from TERRA and are mainly degraded by the general cytoplasmic and nuclear 5′- and 3′- RNA decay pathways in a transcription-dependent manner. subTERRA accumulates preferentially during the G1/S transition and in C-terminal rap1 mutant but independently of Rap1p function in silencing. The accumulation of subTERRA in RNA decay mutants coincides with telomere misregulation: shortening of telomeres, loss of telomeric clustering in mitotic cells and changes in silencing of subtelomeric regions. Our data suggest that subtelomeric RNAs expression links telomere maintenance to RNA degradation pathways.
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Affiliation(s)
- Marta Kwapisz
- ncRNA, epigenetics and genome fluidity, Institut Curie, PSL Research University, CNRS UMR3244, Université Pierre et Marie Curie, 26 rue d’Ulm, 75248 Paris Cedex 05, France; E-Mail: (M.D.)
- Authors to whom correspondence should be addressed; E-Mails: (M.K.); (A.M.); Tel.: +33-561-335-824 (M.K.); +33-(0)-156-246-515 (A.M.); Fax: +33-524-335-886 (M.K.); +33-(0)-156-246-674 (A.M.)
| | - Myriam Ruault
- Nuclear Dynamics, Institut Curie, PSL Research University, CNRS UMR3664, Université Pierre et Marie Curie, 26 rue d’Ulm, 75248 Paris Cedex 05, France; E-Mails: (M.R.); (A.T.)
| | - Erwin van Dijk
- ncRNA, epigenetics and genome fluidity, Institut Curie, PSL Research University, CNRS UMR3244, Université Pierre et Marie Curie, 26 rue d’Ulm, 75248 Paris Cedex 05, France; E-Mail: (M.D.)
| | - Stephanie Gourvennec
- ncRNA, epigenetics and genome fluidity, Institut Curie, PSL Research University, CNRS UMR3244, Université Pierre et Marie Curie, 26 rue d’Ulm, 75248 Paris Cedex 05, France; E-Mail: (M.D.)
| | - Marc Descrimes
- ncRNA, epigenetics and genome fluidity, Institut Curie, PSL Research University, CNRS UMR3244, Université Pierre et Marie Curie, 26 rue d’Ulm, 75248 Paris Cedex 05, France; E-Mail: (M.D.)
| | - Angela Taddei
- Nuclear Dynamics, Institut Curie, PSL Research University, CNRS UMR3664, Université Pierre et Marie Curie, 26 rue d’Ulm, 75248 Paris Cedex 05, France; E-Mails: (M.R.); (A.T.)
| | - Antonin Morillon
- ncRNA, epigenetics and genome fluidity, Institut Curie, PSL Research University, CNRS UMR3244, Université Pierre et Marie Curie, 26 rue d’Ulm, 75248 Paris Cedex 05, France; E-Mail: (M.D.)
- Authors to whom correspondence should be addressed; E-Mails: (M.K.); (A.M.); Tel.: +33-561-335-824 (M.K.); +33-(0)-156-246-515 (A.M.); Fax: +33-524-335-886 (M.K.); +33-(0)-156-246-674 (A.M.)
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23
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Churikov D, Charifi F, Simon MN, Géli V. Rad59-facilitated acquisition of Y' elements by short telomeres delays the onset of senescence. PLoS Genet 2014; 10:e1004736. [PMID: 25375789 PMCID: PMC4222662 DOI: 10.1371/journal.pgen.1004736] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2014] [Accepted: 09/05/2014] [Indexed: 12/25/2022] Open
Abstract
Telomerase-negative yeasts survive via one of the two Rad52-dependent recombination pathways, which have distinct genetic requirements. Although the telomere pattern of type I and type II survivors is well characterized, the mechanistic details of short telomere rearrangement into highly evolved pattern observed in survivors are still missing. Here, we analyze immediate events taking place at the abruptly shortened VII-L and native telomeres. We show that short telomeres engage in pairing with internal Rap1-bound TG1–3-like tracts present between subtelomeric X and Y′ elements, which is followed by BIR-mediated non-reciprocal translocation of Y′ element and terminal TG1–3 repeats from the donor end onto the shortened telomere. We found that choice of the Y′ donor was not random, since both engineered telomere VII-L and native VI-R acquired Y′ elements from partially overlapping sets of specific chromosome ends. Although short telomere repair was associated with transient delay in cell divisions, Y′ translocation on native telomeres did not require Mec1-dependent checkpoint. Furthermore, the homeologous pairing between the terminal TG1–3 repeats at VII-L and internal repeats on other chromosome ends was largely independent of Rad51, but instead it was facilitated by Rad59 that stimulates Rad52 strand annealing activity. Therefore, Y′ translocation events taking place during presenescence are genetically separable from Rad51-dependent Y′ amplification process that occurs later during type I survivor formation. We show that Rad59-facilitated Y′ translocations on X-only telomeres delay the onset of senescence while preparing ground for type I survivor formation. In humans, telomerase is expressed in the germline and stem, but is repressed in somatic cells, which limits replicative lifespan of the latter. To unleash cell proliferation, telomerase is reactivated in most human cancers, but some cancer cells employ alternative lengthening of telomeres (ALT) based on homologous recombination (HR) to escape senescence. Recombination-based telomere maintenance similar to ALT was originally discovered in budding yeast deficient in telomerase activity. Two types of telomere arrangement that depend on two genetically distinct HR pathways (RAD51- and RAD59-dependent) were identified in post-senescent survivors, but the transition to telomere maintenance by HR is poorly understood. Here, we show that one of the earliest steps of short telomere rearrangement in telomerase-negative yeast is directly related to the “short telomere rescue pathway” proposed 20 years ago by Lundblad and Blackburn, which culminates in the acquisition of subtelomeric Y′ element by shortened telomere. We found that this telomere rearrangement depends on Rad52 strand annealing activity stimulated by Rad59, thus it is distinct from Rad51-dependent Y′ amplification process observed in type I survivors. We show that continuous repair of critically short telomeres in telomerase-negative cells delays the onset of senescence and prepares the ground for telomere maintenance by HR.
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Affiliation(s)
- Dmitri Churikov
- Marseille Cancer Research Center (CRCM), U1068 Inserm, UMR7258 CNRS, Aix Marseille University, Institut Paoli-Calmettes, LNCC (Equipe labellisée), Marseille, France
| | - Ferose Charifi
- Marseille Cancer Research Center (CRCM), U1068 Inserm, UMR7258 CNRS, Aix Marseille University, Institut Paoli-Calmettes, LNCC (Equipe labellisée), Marseille, France
| | - Marie-Noëlle Simon
- Marseille Cancer Research Center (CRCM), U1068 Inserm, UMR7258 CNRS, Aix Marseille University, Institut Paoli-Calmettes, LNCC (Equipe labellisée), Marseille, France
| | - Vincent Géli
- Marseille Cancer Research Center (CRCM), U1068 Inserm, UMR7258 CNRS, Aix Marseille University, Institut Paoli-Calmettes, LNCC (Equipe labellisée), Marseille, France
- * E-mail:
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24
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Sridhar A, Kedziora S, Donaldson AD. At short telomeres Tel1 directs early replication and phosphorylates Rif1. PLoS Genet 2014; 10:e1004691. [PMID: 25329891 PMCID: PMC4199499 DOI: 10.1371/journal.pgen.1004691] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2013] [Accepted: 08/20/2014] [Indexed: 11/19/2022] Open
Abstract
The replication time of Saccharomyces cerevisiae telomeres responds to TG1-3 repeat length, with telomeres of normal length replicating late during S phase and short telomeres replicating early. Here we show that Tel1 kinase, which is recruited to short telomeres, specifies their early replication, because we find a tel1Δ mutant has short telomeres that nonetheless replicate late. Consistent with a role for Tel1 in driving early telomere replication, initiation at a replication origin close to an induced short telomere was reduced in tel1Δ cells, in an S phase blocked by hydroxyurea. The telomeric chromatin component Rif1 mediates late replication of normal telomeres and is a potential substrate of Tel1 phosphorylation, so we tested whether Tel1 directs early replication of short telomeres by inactivating Rif1. A strain lacking both Rif1 and Tel1 behaves like a rif1Δ mutant by replicating its telomeres early, implying that Tel1 can counteract the delaying effect of Rif1 to control telomere replication time. Proteomic analyses reveals that in yku70Δ cells that have short telomeres, Rif1 is phosphorylated at Tel1 consensus sequences (S/TQ sites), with phosphorylation of Serine-1308 being completely dependent on Tel1. Replication timing analysis of a strain mutated at these phosphorylation sites, however, suggested that Tel1-mediated phosphorylation of Rif1 is not the sole mechanism of replication timing control at telomeres. Overall, our results reveal two new functions of Tel1 at shortened telomeres: phosphorylation of Rif1, and specification of early replication by counteracting the Rif1-mediated delay in initiation at nearby replication origins.
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Affiliation(s)
- Akila Sridhar
- Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen, Scotland, United Kingdom
| | - Sylwia Kedziora
- Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen, Scotland, United Kingdom
| | - Anne D. Donaldson
- Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen, Scotland, United Kingdom
- * E-mail:
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25
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Abstract
Telomerase action is temporally linked to DNA replication. Although yeast telomeres are normally late replicating, telomere shortening leads to early firing of subtelomeric DNA replication origins. We show that double-strand breaks flanked by short telomeric arrays cause origin firing early in S phase at late-replicating loci and that this effect on origin firing time is dependent on the Tel1ATM checkpoint kinase. The effect of Tel1ATM on telomere replication timing extends to endogenous telomeres and is stronger than that elicited by Rif1 loss. These results establish that Tel1ATM specifies not only the extent but also the timing of telomerase recruitment.
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Affiliation(s)
- Carol Cooley
- Genome Damage and Stability Centre, School of Life Sciences University of Sussex, Brighton, UK
| | - Anoushka Davé
- Genome Damage and Stability Centre, School of Life Sciences University of Sussex, Brighton, UK
| | - Mansi Garg
- Genome Damage and Stability Centre, School of Life Sciences University of Sussex, Brighton, UK
| | - Alessandro Bianchi
- Genome Damage and Stability Centre, School of Life Sciences University of Sussex, Brighton, UK
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26
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Temporal and spatial regulation of eukaryotic DNA replication: From regulated initiation to genome-scale timing program. Semin Cell Dev Biol 2014; 30:110-20. [DOI: 10.1016/j.semcdb.2014.04.014] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2014] [Accepted: 04/04/2014] [Indexed: 11/23/2022]
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27
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Peace JM, Ter-Zakarian A, Aparicio OM. Rif1 regulates initiation timing of late replication origins throughout the S. cerevisiae genome. PLoS One 2014; 9:e98501. [PMID: 24879017 PMCID: PMC4039536 DOI: 10.1371/journal.pone.0098501] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2014] [Accepted: 05/03/2014] [Indexed: 12/20/2022] Open
Abstract
Chromosomal DNA replication involves the coordinated activity of hundreds to thousands of replication origins. Individual replication origins are subject to epigenetic regulation of their activity during S-phase, resulting in differential efficiencies and timings of replication initiation during S-phase. This regulation is thought to involve chromatin structure and organization into timing domains with differential ability to recruit limiting replication factors. Rif1 has recently been identified as a genome-wide regulator of replication timing in fission yeast and in mammalian cells. However, previous studies in budding yeast have suggested that Rif1’s role in controlling replication timing may be limited to subtelomeric domains and derives from its established role in telomere length regulation. We have analyzed replication timing by analyzing BrdU incorporation genome-wide, and report that Rif1 regulates the timing of late/dormant replication origins throughout the S. cerevisiae genome. Analysis of pfa4Δ cells, which are defective in palmitoylation and membrane association of Rif1, suggests that replication timing regulation by Rif1 is independent of its role in localizing telomeres to the nuclear periphery. Intra-S checkpoint signaling is intact in rif1Δ cells, and checkpoint-defective mec1Δ cells do not comparably deregulate replication timing, together indicating that Rif1 regulates replication timing through a mechanism independent of this checkpoint. Our results indicate that the Rif1 mechanism regulates origin timing irrespective of proximity to a chromosome end, and suggest instead that telomere sequences merely provide abundant binding sites for proteins that recruit Rif1. Still, the abundance of Rif1 binding in telomeric domains may facilitate Rif1-mediated repression of non-telomeric origins that are more distal from centromeres.
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Affiliation(s)
- Jared M. Peace
- Molecular and Computational Biology Program, University of Southern California, Los Angeles, California, United States of America
| | - Anna Ter-Zakarian
- Program in Global Medicine, Keck School of Medicine, University of Southern California, Los Angeles, California, United States of America
| | - Oscar M. Aparicio
- Molecular and Computational Biology Program, University of Southern California, Los Angeles, California, United States of America
- * E-mail:
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28
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Rif1 controls DNA replication timing in yeast through the PP1 phosphatase Glc7. Cell Rep 2014; 7:62-9. [PMID: 24685139 DOI: 10.1016/j.celrep.2014.03.010] [Citation(s) in RCA: 139] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2014] [Revised: 02/15/2014] [Accepted: 03/06/2014] [Indexed: 12/27/2022] Open
Abstract
The Rif1 protein, originally identified as a telomere-binding factor in yeast, has recently been implicated in DNA replication control from yeast to metazoans. Here, we show that budding yeast Rif1 protein inhibits activation of prereplication complexes (pre-RCs). This inhibitory function requires two N-terminal motifs, RVxF and SILK, associated with recruitment of PP1 phosphatase (Glc7). In G1 phase, we show both that Glc7 interacts with Rif1 in an RVxF/SILK-dependent manner and that two proteins implicated in pre-RC activation, Mcm4 and Sld3, display increased Dbf4-dependent kinase (DDK) phosphorylation in rif1 mutants. Rif1 also interacts with Dbf4 in yeast two-hybrid assays, further implicating this protein in direct modulation of pre-RC activation through the DDK. Finally, we demonstrate Rif1 RVxF/SILK motif-dependent recruitment of Glc7 to telomeres and earlier replication of these regions in cells where the motifs are mutated. Our data thus link Rif1 to negative regulation of replication origin firing through recruitment of the Glc7 phosphatase.
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Davé A, Cooley C, Garg M, Bianchi A. Protein phosphatase 1 recruitment by Rif1 regulates DNA replication origin firing by counteracting DDK activity. Cell Rep 2014; 7:53-61. [PMID: 24656819 PMCID: PMC3989773 DOI: 10.1016/j.celrep.2014.02.019] [Citation(s) in RCA: 139] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2013] [Revised: 01/20/2014] [Accepted: 02/14/2014] [Indexed: 01/23/2023] Open
Abstract
The firing of eukaryotic origins of DNA replication requires CDK and DDK kinase activities. DDK, in particular, is involved in setting the temporal program of origin activation, a conserved feature of eukaryotes. Rif1, originally identified as a telomeric protein, was recently implicated in specifying replication timing in yeast and mammals. We show that this function of Rif1 depends on its interaction with PP1 phosphatases. Mutations of two PP1 docking motifs in Rif1 lead to early replication of telomeres in budding yeast and misregulation of origin firing in fission yeast. Several lines of evidence indicate that Rif1/PP1 counteract DDK activity on the replicative MCM helicase. Our data suggest that the PP1/Rif1 interaction is downregulated by the phosphorylation of Rif1, most likely by CDK/DDK. These findings elucidate the mechanism of action of Rif1 in the control of DNA replication and demonstrate a role of PP1 phosphatases in the regulation of origin firing. Rif1 recruits protein phosphatase 1 to telomeres and DNA replication origins PP1 docking motifs mediate the effect of Rif1 on DNA replication timing The PP1 recruitment activity of Rif1 counteracts DDK action on Mcm4 Mutations in putative CDK/DDK sites near the PP1 motifs in Rif1 affect PP1 recruitment
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Affiliation(s)
- Anoushka Davé
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Brighton BN1 9RQ, UK
| | - Carol Cooley
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Brighton BN1 9RQ, UK
| | - Mansi Garg
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Brighton BN1 9RQ, UK
| | - Alessandro Bianchi
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Brighton BN1 9RQ, UK.
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Telomere recombination preferentially occurs at short telomeres in telomerase-null type II survivors. PLoS One 2014; 9:e90644. [PMID: 24594632 PMCID: PMC3940914 DOI: 10.1371/journal.pone.0090644] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2013] [Accepted: 02/03/2014] [Indexed: 01/17/2023] Open
Abstract
In telomerase negative yeast cells, Rad52-dependent recombination is activated to maintain telomeres. This recombination-mediated telomere elongation usually involves two independent pathways, type I and type II, and leads to generation of type I and type II survivors. It remains elusive whether the recombination-mediated telomere elongation prefers to take place on shorter or longer telomeres. In this study, we exploited the de novo telomere addition system to examine the telomere recombination event in telomerase negative cells. We show that recombination preferentially occurs on shorter rather than longer telomeres in both pre-survivors and established type II survivors. In type II survivors, the short VII–L telomeres could invade either terminal TG1–3 sequence or short tracts of TG1–3 sequence in subtelomeric Y′-X and Y′-Y′ junction to initiate recombination. Unexpectedly, short VII–L telomere recombination still takes place in type II survivors lacking either Rad50 or Rad59, which are required for type II survivor generation in senescing telomerase-null cells. Our results support the notion that Rad50 and Rad59 are not essential for the maintenance of type II survivors once established.
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Abstract
Telomerase reverse transcriptase (TERT) is the protein component of telomerase and combined with an RNA molecule, telomerase RNA component, forms the telomerase enzyme responsible for telomere elongation. Telomerase is essential for maintaining telomere length from replicative attrition and thus contributes to the preservation of genome integrity. Although diverse mouse models have been developed and studied to prove the physiological roles of telomerase as a telomere- elongating enzyme, recent studies have revealed non-canonical TERT activities beyond telomeres. To gain insights into the physiological impact of extra-telomeric roles, this review revisits the strategies and phenotypes of telomerase mouse models in terms of the extra-telomeric functions of telomerase.
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Affiliation(s)
- Young Hoon Sung
- Department of Biochemistry, College of Life Science and Biotechnology, Laboratory Animal Research Center, Yonsei University, Seoul, Korea
| | - Muhammad Ali
- Department of Biochemistry, College of Life Science and Biotechnology, Laboratory Animal Research Center, Yonsei University, Seoul, Korea
| | - Han-Woong Lee
- Department of Biochemistry, College of Life Science and Biotechnology, Laboratory Animal Research Center, Yonsei University, Seoul, Korea
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Chang YT, Moser BA, Nakamura TM. Fission yeast shelterin regulates DNA polymerases and Rad3(ATR) kinase to limit telomere extension. PLoS Genet 2013; 9:e1003936. [PMID: 24244195 PMCID: PMC3820796 DOI: 10.1371/journal.pgen.1003936] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2013] [Accepted: 09/17/2013] [Indexed: 11/19/2022] Open
Abstract
Studies in fission yeast have previously identified evolutionarily conserved shelterin and Stn1-Ten1 complexes, and established Rad3ATR/Tel1ATM-dependent phosphorylation of the shelterin subunit Ccq1 at Thr93 as the critical post-translational modification for telomerase recruitment to telomeres. Furthermore, shelterin subunits Poz1, Rap1 and Taz1 have been identified as negative regulators of Thr93 phosphorylation and telomerase recruitment. However, it remained unclear how telomere maintenance is dynamically regulated during the cell cycle. Thus, we investigated how loss of Poz1, Rap1 and Taz1 affects cell cycle regulation of Ccq1 Thr93 phosphorylation and telomere association of telomerase (Trt1TERT), DNA polymerases, Replication Protein A (RPA) complex, Rad3ATR-Rad26ATRIP checkpoint kinase complex, Tel1ATM kinase, shelterin subunits (Tpz1, Ccq1 and Poz1) and Stn1. We further investigated how telomere shortening, caused by trt1Δ or catalytically dead Trt1-D743A, affects cell cycle-regulated telomere association of telomerase and DNA polymerases. These analyses established that fission yeast shelterin maintains telomere length homeostasis by coordinating the differential arrival of leading (Polε) and lagging (Polα) strand DNA polymerases at telomeres to modulate Rad3ATR association, Ccq1 Thr93 phosphorylation and telomerase recruitment. Stable maintenance of telomeres is critical to maintain a stable genome and to prevent accumulation of undesired mutations that may lead to formation of tumors. Telomere dysfunction can also lead to premature aging due to depletion of the stem cell population, highlighting the importance of understanding the regulatory mechanisms that ensure stable telomere maintenance. Based on careful analysis of cell cycle-regulated changes in telomere association of telomerase, DNA polymerases, Replication Protein A, checkpoint kinases, telomere protection complex shelterin, and Stn1-Ten1 complex, we will provide here a new and dynamic model of telomere length regulation in fission yeast, which suggests that shelterin-dependent regulation of differential arrival of leading and lagging strand DNA polymerase at telomeres is responsible for modulating Rad3ATR checkpoint kinase accumulation and Rad3ATR-dependent phosphorylation of shelterin subunit Ccq1 to control telomerase recruitment to telomeres.
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Affiliation(s)
- Ya-Ting Chang
- Department of Biochemistry and Molecular Genetics, College of Medicine, University of Illinois at Chicago, Chicago, Illinois, United States of America
| | - Bettina A. Moser
- Department of Biochemistry and Molecular Genetics, College of Medicine, University of Illinois at Chicago, Chicago, Illinois, United States of America
| | - Toru M. Nakamura
- Department of Biochemistry and Molecular Genetics, College of Medicine, University of Illinois at Chicago, Chicago, Illinois, United States of America
- * E-mail:
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Replication timing regulation of eukaryotic replicons: Rif1 as a global regulator of replication timing. Trends Genet 2013; 29:449-60. [DOI: 10.1016/j.tig.2013.05.001] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2013] [Revised: 04/27/2013] [Accepted: 05/01/2013] [Indexed: 12/13/2022]
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35
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Koltovaya NA. Involvement of cyclin-dependent kinase CDK1/CDC28 in regulation of cell cycle. RUSS J GENET+ 2013. [DOI: 10.1134/s1022795413050086] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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36
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Pfeiffer V, Lingner J. Replication of telomeres and the regulation of telomerase. Cold Spring Harb Perspect Biol 2013; 5:a010405. [PMID: 23543032 DOI: 10.1101/cshperspect.a010405] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Telomeres are the physical ends of eukaryotic chromosomes. They protect chromosome ends from DNA degradation, recombination, and DNA end fusions, and they are important for nuclear architecture. Telomeres provide a mechanism for their replication by semiconservative DNA replication and length maintenance by telomerase. Through telomerase repression and induced telomere shortening, telomeres provide the means to regulate cellular life span. In this review, we introduce the current knowledge on telomere composition and structure. We then discuss in depth the current understanding of how telomere components mediate their function during semiconservative DNA replication and how telomerase is regulated at the end of the chromosome. We focus our discussion on the telomeres from mammals and the yeasts Saccharomyces cerevisiae and Schizosaccharomyces pombe.
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Affiliation(s)
- Verena Pfeiffer
- Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences, Frontiers in Genetics National Center of Competence in Research, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
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37
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Lemmens L, Mattarocci S, Marcomini I, Shi T, Follonier C, Lopes M, Thomä N, Shore D. Global control of DNA replication timing by the budding yeast telomere protein Rif1. Epigenetics Chromatin 2013. [PMCID: PMC3600763 DOI: 10.1186/1756-8935-6-s1-p99] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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Abstract
Budding yeast, like other eukaryotes, carries its genetic information on chromosomes that are sequestered from other cellular constituents by a double membrane, which forms the nucleus. An elaborate molecular machinery forms large pores that span the double membrane and regulate the traffic of macromolecules into and out of the nucleus. In multicellular eukaryotes, an intermediate filament meshwork formed of lamin proteins bridges from pore to pore and helps the nucleus reform after mitosis. Yeast, however, lacks lamins, and the nuclear envelope is not disrupted during yeast mitosis. The mitotic spindle nucleates from the nucleoplasmic face of the spindle pole body, which is embedded in the nuclear envelope. Surprisingly, the kinetochores remain attached to short microtubules throughout interphase, influencing the position of centromeres in the interphase nucleus, and telomeres are found clustered in foci at the nuclear periphery. In addition to this chromosomal organization, the yeast nucleus is functionally compartmentalized to allow efficient gene expression, repression, RNA processing, genomic replication, and repair. The formation of functional subcompartments is achieved in the nucleus without intranuclear membranes and depends instead on sequence elements, protein-protein interactions, specific anchorage sites at the nuclear envelope or at pores, and long-range contacts between specific chromosomal loci, such as telomeres. Here we review the spatial organization of the budding yeast nucleus, the proteins involved in forming nuclear subcompartments, and evidence suggesting that the spatial organization of the nucleus is important for nuclear function.
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Donley N, Thayer MJ. DNA replication timing, genome stability and cancer: late and/or delayed DNA replication timing is associated with increased genomic instability. Semin Cancer Biol 2013; 23:80-9. [PMID: 23327985 DOI: 10.1016/j.semcancer.2013.01.001] [Citation(s) in RCA: 90] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Accepted: 01/04/2013] [Indexed: 11/30/2022]
Abstract
Normal cellular division requires that the genome be faithfully replicated to ensure that unaltered genomic information is passed from one generation to the next. DNA replication initiates from thousands of origins scattered throughout the genome every cell cycle; however, not all origins initiate replication at the same time. A vast amount of work over the years indicates that different origins along each eukaryotic chromosome are activated in early, middle or late S phase. This temporal control of DNA replication is referred to as the replication-timing program. The replication-timing program represents a very stable epigenetic feature of chromosomes. Recent evidence has indicated that the replication-timing program can influence the spatial distribution of mutagenic events such that certain regions of the genome experience increased spontaneous mutagenesis compared to surrounding regions. This influence has helped shape the genomes of humans and other multicellular organisms and can affect the distribution of mutations in somatic cells. It is also becoming clear that the replication-timing program is deregulated in many disease states, including cancer. Aberrant DNA replication timing is associated with changes in gene expression, changes in epigenetic modifications and an increased frequency of structural rearrangements. Furthermore, certain replication timing changes can directly lead to overt genomic instability and may explain unique mutational signatures that are present in cells that have undergone the recently described processes of "chromothripsis" and "kataegis". In this review, we will discuss how the normal replication timing program, as well as how alterations to this program, can contribute to the evolution of the genomic landscape in normal and cancerous cells.
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Affiliation(s)
- Nathan Donley
- Department of Biochemistry and Molecular Biology, Oregon Health & Science University, Knight Cancer Institute, 3181 S.W. Sam Jackson Park Road, Portland, OR 97239, USA
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40
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Abstract
The mechanisms that maintain the stability of chromosome ends have broad impact on genome integrity in all eukaryotes. Budding yeast is a premier organism for telomere studies. Many fundamental concepts of telomere and telomerase function were first established in yeast and then extended to other organisms. We present a comprehensive review of yeast telomere biology that covers capping, replication, recombination, and transcription. We think of it as yeast telomeres—soup to nuts.
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41
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Wu Y, DiMaggio PA, Perlman DH, Zakian VA, Garcia BA. Novel phosphorylation sites in the S. cerevisiae Cdc13 protein reveal new targets for telomere length regulation. J Proteome Res 2012. [PMID: 23181431 DOI: 10.1021/pr300408v] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The S. cerevisiae Cdc13 is a multifunctional protein with key roles in regulation of telomerase, telomere end protection, and conventional telomere replication, all of which are cell cycle-regulated processes. Given that phosphorylation is a key mechanism for regulating protein function, we identified sites of phosphorylation using nano liquid chromatography-tandem mass spectrometry (nanoLC-MS/MS). We also determined phosphorylation abundance on both wild type (WT) and a telomerase deficient form of Cdc13, encoded by the cdc13-2 allele, in both G1 phase cells, when telomerase is not active, and G2/M phase cells, when it is. We identified 21 sites of in vivo phosphorylation, of which only five had been reported previously. In contrast, phosphorylation of two in vitro targets of the ATM-like Tel1 kinase, S249 and S255, was not detected. This result helps resolve conflicting data on the importance of phosphorylation of these residues in telomerase recruitment. Multiple residues showed differences in their cell cycle pattern of modification. For example, phosphorylation of S314 was significantly higher in the G2/M compared to the G1 phase and in WT versus mutant Cdc13, and a S314D mutation negatively affected telomere length. Our findings provide new targets in a key telomerase regulatory protein for modulation of telomere dynamics.
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Affiliation(s)
- Yun Wu
- Department of Molecular Biology, Princeton University, Princeton, New Jersey 08544, United States
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Tazumi A, Fukuura M, Nakato R, Kishimoto A, Takenaka T, Ogawa S, Song JH, Takahashi TS, Nakagawa T, Shirahige K, Masukata H. Telomere-binding protein Taz1 controls global replication timing through its localization near late replication origins in fission yeast. Genes Dev 2012; 26:2050-62. [PMID: 22987637 DOI: 10.1101/gad.194282.112] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
In eukaryotes, the replication of chromosome DNA is coordinated by a replication timing program that temporally regulates the firing of individual replication origins. However, the molecular mechanism underlying the program remains elusive. Here, we report that the telomere-binding protein Taz1 plays a crucial role in the control of replication timing in fission yeast. A DNA element located proximal to a late origin in the chromosome arm represses initiation from the origin in early S phase. Systematic deletion and substitution experiments demonstrated that two tandem telomeric repeats are essential for this repression. The telomeric repeats recruit Taz1, a counterpart of human TRF1 and TRF2, to the locus. Genome-wide analysis revealed that Taz1 regulates about half of chromosomal late origins, including those in subtelomeres. The Taz1-mediated mechanism prevents Dbf4-dependent kinase (DDK)-dependent Sld3 loading onto the origins. Our results demonstrate that the replication timing program in fission yeast uses the internal telomeric repeats and binding of Taz1.
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Affiliation(s)
- Atsutoshi Tazumi
- Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka, Japan
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Müller CA, Nieduszynski CA. Conservation of replication timing reveals global and local regulation of replication origin activity. Genome Res 2012; 22:1953-62. [PMID: 22767388 PMCID: PMC3460190 DOI: 10.1101/gr.139477.112] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
DNA replication initiates from defined locations called replication origins; some origins are highly active, whereas others are dormant and rarely used. Origins also differ in their activation time, resulting in particular genomic regions replicating at characteristic times and in a defined temporal order. Here we report the comparison of genome replication in four budding yeast species: Saccharomyces cerevisiae, S. paradoxus, S. arboricolus, and S. bayanus. First, we find that the locations of active origins are predominantly conserved between species, whereas dormant origins are poorly conserved. Second, we generated genome-wide replication profiles for each of these species and discovered that the temporal order of genome replication is highly conserved. Therefore, active origins are not only conserved in location, but also in activation time. Only a minority of these conserved origins show differences in activation time between these species. To gain insight as to the mechanisms by which origin activation time is regulated we generated replication profiles for a S. cerevisiae/S. bayanus hybrid strain and find that there are both local and global regulators of origin function.
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Affiliation(s)
- Carolin A Müller
- Centre for Genetics and Genomics, The University of Nottingham, Medical School, Queen's Medical Centre, Nottingham NG7 2UH, United Kingdom
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Dehé PM, Rog O, Ferreira M, Greenwood J, Cooper J. Taz1 Enforces Cell-Cycle Regulation of Telomere Synthesis. Mol Cell 2012; 46:797-808. [DOI: 10.1016/j.molcel.2012.04.022] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2011] [Revised: 02/21/2012] [Accepted: 04/13/2012] [Indexed: 01/14/2023]
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Abstract
Telomeres are essential for the stability and complete replication of linear chromosomes. Telomere elongation by telomerase counteracts the telomere shortening due to the incomplete replication of chromosome ends by DNA polymerase. Telomere elongation is cell-cycle-regulated and coupled to DNA replication during S-phase. However, the molecular mechanisms that underlie such cell-cycle-dependent telomere elongation by telomerase remain largely unknown. Several aspects of telomere replication in budding yeast, including the modulation of telomere chromatin structure, telomere end processing, recruitment of telomere-binding proteins and telomerase complex to telomere as well as the coupling of DNA replication to telomere elongation during cell cycle progression will be discussed, and the potential roles of Cdk (cyclin-dependent kinase) in these processes will be illustrated.
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46
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Addinall SG, Holstein EM, Lawless C, Yu M, Chapman K, Banks AP, Ngo HP, Maringele L, Taschuk M, Young A, Ciesiolka A, Lister AL, Wipat A, Wilkinson DJ, Lydall D. Quantitative fitness analysis shows that NMD proteins and many other protein complexes suppress or enhance distinct telomere cap defects. PLoS Genet 2011; 7:e1001362. [PMID: 21490951 PMCID: PMC3072368 DOI: 10.1371/journal.pgen.1001362] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2010] [Accepted: 03/02/2011] [Indexed: 12/20/2022] Open
Abstract
To better understand telomere biology in budding yeast, we have performed systematic suppressor/enhancer analyses on yeast strains containing a point mutation in the essential telomere capping gene CDC13 (cdc13-1) or containing a null mutation in the DNA damage response and telomere capping gene YKU70 (yku70Δ). We performed Quantitative Fitness Analysis (QFA) on thousands of yeast strains containing mutations affecting telomere-capping proteins in combination with a library of systematic gene deletion mutations. To perform QFA, we typically inoculate 384 separate cultures onto solid agar plates and monitor growth of each culture by photography over time. The data are fitted to a logistic population growth model; and growth parameters, such as maximum growth rate and maximum doubling potential, are deduced. QFA reveals that as many as 5% of systematic gene deletions, affecting numerous functional classes, strongly interact with telomere capping defects. We show that, while Cdc13 and Yku70 perform complementary roles in telomere capping, their genetic interaction profiles differ significantly. At least 19 different classes of functionally or physically related proteins can be identified as interacting with cdc13-1, yku70Δ, or both. Each specific genetic interaction informs the roles of individual gene products in telomere biology. One striking example is with genes of the nonsense-mediated RNA decay (NMD) pathway which, when disabled, suppress the conditional cdc13-1 mutation but enhance the null yku70Δ mutation. We show that the suppressing/enhancing role of the NMD pathway at uncapped telomeres is mediated through the levels of Stn1, an essential telomere capping protein, which interacts with Cdc13 and recruitment of telomerase to telomeres. We show that increased Stn1 levels affect growth of cells with telomere capping defects due to cdc13-1 and yku70Δ. QFA is a sensitive, high-throughput method that will also be useful to understand other aspects of microbial cell biology.
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Affiliation(s)
- Stephen Gregory Addinall
- Institute for Cell and Molecular Biosciences, Newcastle University Medical School, Newcastle upon Tyne, United Kingdom
- Centre for Integrated Systems Biology of Ageing and Nutrition, Institute for Ageing and Health, Newcastle University Campus for Ageing and Vitality, Newcastle upon Tyne, United Kingdom
| | - Eva-Maria Holstein
- Institute for Cell and Molecular Biosciences, Newcastle University Medical School, Newcastle upon Tyne, United Kingdom
- Centre for Integrated Systems Biology of Ageing and Nutrition, Institute for Ageing and Health, Newcastle University Campus for Ageing and Vitality, Newcastle upon Tyne, United Kingdom
| | - Conor Lawless
- Centre for Integrated Systems Biology of Ageing and Nutrition, Institute for Ageing and Health, Newcastle University Campus for Ageing and Vitality, Newcastle upon Tyne, United Kingdom
| | - Min Yu
- Institute for Cell and Molecular Biosciences, Newcastle University Medical School, Newcastle upon Tyne, United Kingdom
- Centre for Integrated Systems Biology of Ageing and Nutrition, Institute for Ageing and Health, Newcastle University Campus for Ageing and Vitality, Newcastle upon Tyne, United Kingdom
| | - Kaye Chapman
- Institute for Cell and Molecular Biosciences, Newcastle University Medical School, Newcastle upon Tyne, United Kingdom
- Centre for Integrated Systems Biology of Ageing and Nutrition, Institute for Ageing and Health, Newcastle University Campus for Ageing and Vitality, Newcastle upon Tyne, United Kingdom
| | - A. Peter Banks
- Institute for Cell and Molecular Biosciences, Newcastle University Medical School, Newcastle upon Tyne, United Kingdom
- Centre for Integrated Systems Biology of Ageing and Nutrition, Institute for Ageing and Health, Newcastle University Campus for Ageing and Vitality, Newcastle upon Tyne, United Kingdom
| | - Hien-Ping Ngo
- Institute for Cell and Molecular Biosciences, Newcastle University Medical School, Newcastle upon Tyne, United Kingdom
| | - Laura Maringele
- Crucible Laboratory, Institute for Ageing and Health, Newcastle University Centre for Life, Newcastle upon Tyne, United Kingdom
| | - Morgan Taschuk
- Centre for Integrated Systems Biology of Ageing and Nutrition, Institute for Ageing and Health, Newcastle University Campus for Ageing and Vitality, Newcastle upon Tyne, United Kingdom
- School of Computing Science, Newcastle University, Newcastle Upon Tyne, United Kingdom
| | - Alexander Young
- Centre for Integrated Systems Biology of Ageing and Nutrition, Institute for Ageing and Health, Newcastle University Campus for Ageing and Vitality, Newcastle upon Tyne, United Kingdom
- School of Mathematics and Statistics, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Adam Ciesiolka
- Institute for Cell and Molecular Biosciences, Newcastle University Medical School, Newcastle upon Tyne, United Kingdom
- Centre for Integrated Systems Biology of Ageing and Nutrition, Institute for Ageing and Health, Newcastle University Campus for Ageing and Vitality, Newcastle upon Tyne, United Kingdom
| | - Allyson Lurena Lister
- Centre for Integrated Systems Biology of Ageing and Nutrition, Institute for Ageing and Health, Newcastle University Campus for Ageing and Vitality, Newcastle upon Tyne, United Kingdom
- School of Computing Science, Newcastle University, Newcastle Upon Tyne, United Kingdom
| | - Anil Wipat
- Institute for Cell and Molecular Biosciences, Newcastle University Medical School, Newcastle upon Tyne, United Kingdom
- Centre for Integrated Systems Biology of Ageing and Nutrition, Institute for Ageing and Health, Newcastle University Campus for Ageing and Vitality, Newcastle upon Tyne, United Kingdom
- School of Computing Science, Newcastle University, Newcastle Upon Tyne, United Kingdom
| | - Darren James Wilkinson
- Centre for Integrated Systems Biology of Ageing and Nutrition, Institute for Ageing and Health, Newcastle University Campus for Ageing and Vitality, Newcastle upon Tyne, United Kingdom
- School of Mathematics and Statistics, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - David Lydall
- Institute for Cell and Molecular Biosciences, Newcastle University Medical School, Newcastle upon Tyne, United Kingdom
- Centre for Integrated Systems Biology of Ageing and Nutrition, Institute for Ageing and Health, Newcastle University Campus for Ageing and Vitality, Newcastle upon Tyne, United Kingdom
- * E-mail:
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47
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Lian HY, Robertson ED, Hiraga SI, Alvino GM, Collingwood D, McCune HJ, Sridhar A, Brewer BJ, Raghuraman MK, Donaldson AD. The effect of Ku on telomere replication time is mediated by telomere length but is independent of histone tail acetylation. Mol Biol Cell 2011; 22:1753-65. [PMID: 21441303 PMCID: PMC3093326 DOI: 10.1091/mbc.e10-06-0549] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Ku controls telomere replication timing. We test the mechanism and find that Ku does not bind telomere-proximal origins directly or alter their histone acetylation state. Instead, Ku's effect on replication timing is mediated through telomere length and requires the TG1-3 repeat-counting component Rif1. DNA replication in Saccharomyces cerevisiae proceeds according to a temporal program. We have investigated the role of the telomere-binding Ku complex in specifying late replication of telomere-proximal sequences. Genome-wide analysis shows that regions extending up to 80 kb from telomeres replicate abnormally early in a yku70 mutant. We find that Ku does not appear to regulate replication time by binding replication origins directly, nor is its effect on telomere replication timing mediated by histone tail acetylation. We show that Ku instead regulates replication timing through its effect on telomere length, because deletion of the telomerase regulator Pif1 largely reverses the short telomere defect of a yku70 mutant and simultaneously rescues its replication timing defect. Consistent with this conclusion, deleting the genome integrity component Elg1 partially rescued both length and replication timing of yku70 telomeres. Telomere length–mediated control of replication timing requires the TG1–3 repeat-counting component Rif1, because a rif1 mutant replicates telomeric regions early, despite having extended TG1–3 tracts. Overall, our results suggest that the effect of Ku on telomere replication timing results from its impact on TG1–3 repeat length and support a model in which Rif1 measures telomere repeat length to ensure that telomere replication timing is correctly programmed.
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Affiliation(s)
- Hui-Yong Lian
- Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, Scotland, UK
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48
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O'Sullivan RJ, Kubicek S, Schreiber SL, Karlseder J. Reduced histone biosynthesis and chromatin changes arising from a damage signal at telomeres. Nat Struct Mol Biol 2010; 17:1218-25. [PMID: 20890289 PMCID: PMC2951278 DOI: 10.1038/nsmb.1897] [Citation(s) in RCA: 307] [Impact Index Per Article: 21.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2010] [Accepted: 07/29/2010] [Indexed: 11/09/2022]
Abstract
During replicative aging of primary cells morphological transformations occur, the expression pattern is altered and chromatin changes globally. Here we show that chronic damage signals, likely caused by telomere processing, impact expression of histones and lead to their depletion. Interrogation of the abundance and cell cycle expression of histones and histone chaperones revealed defects in histone biosynthesis during replicative aging. Simultaneously, epigenetic marks were redistributed across the phases of the cell cycle and the DNA damage response (DDR) machinery was activated. The age-dependent reprogramming affected telomeric chromatin itself, which was progressively destabilized, resulting in a boost of the telomere associated DDR signal with each successive cell cycle. We propose a mechanism where changes in the structural and epigenetic integrity of telomeres impact core histones and their chaperones, enforcing a self-perpetuating pathway of global epigenetic changes that ultimately leads to senescence.
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Affiliation(s)
- Roderick J O'Sullivan
- The Salk Institute for Biological Studies, Molecular and Cellular Biology Department, La Jolla, California, USA
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49
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Subramanian L, Nakamura TM. To fuse or not to fuse: how do checkpoint and DNA repair proteins maintain telomeres? FRONT BIOSCI-LANDMRK 2010; 15:1105-18. [PMID: 20515744 PMCID: PMC2880829 DOI: 10.2741/3664] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
DNA damage checkpoint and DNA repair mechanisms play critical roles in the stable maintenance of genetic information. Various forms of DNA damage that arise inside cells due to common errors in normal cellular processes, such as DNA replication, or due to exposure to various DNA damaging agents, must be quickly detected and repaired by checkpoint signaling and repair factors. Telomeres, the natural ends of linear chromosomes, share many features with undesired "broken" DNA, and are recognized and processed by various DNA damage checkpoint and DNA repair proteins. However, their modes of action at telomeres must be altered from their actions at other DNA damage sites to avoid telomere fusions and permanent cell cycle arrest. Interestingly, accumulating evidence indicates that DNA damage checkpoint and DNA repair proteins are essential for telomere maintenance. In this article, we review our current knowledge on various mechanisms by which DNA damage checkpoint and DNA repair proteins are modulated at telomeres and how they might contribute to telomere maintenance in eukaryotes.
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Affiliation(s)
- Lakxmi Subramanian
- Department of Biochemistry and Molecular Genetics, University of Illinois at Chicago, Chicago, IL 60607, USA
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50
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Arnoult N, Schluth-Bolard C, Letessier A, Drascovic I, Bouarich-Bourimi R, Campisi J, Kim SH, Boussouar A, Ottaviani A, Magdinier F, Gilson E, Londoño-Vallejo A. Replication timing of human telomeres is chromosome arm-specific, influenced by subtelomeric structures and connected to nuclear localization. PLoS Genet 2010; 6:e1000920. [PMID: 20421929 PMCID: PMC2858680 DOI: 10.1371/journal.pgen.1000920] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2009] [Accepted: 03/22/2010] [Indexed: 12/12/2022] Open
Abstract
The mechanisms governing telomere replication in humans are still poorly understood. To fill this gap, we investigated the timing of replication of single telomeres in human cells. Using in situ hybridization techniques, we have found that specific telomeres have preferential time windows for replication during the S-phase and that these intervals do not depend upon telomere length and are largely conserved between homologous chromosomes and between individuals, even in the presence of large subtelomeric segmental polymorphisms. Importantly, we show that one copy of the 3.3 kb macrosatellite repeat D4Z4, present in the subtelomeric region of the late replicating 4q35 telomere, is sufficient to confer both a more peripheral localization and a later-replicating property to a de novo formed telomere. Also, the presence of β-satellite repeats next to a newly created telomere is sufficient to delay its replication timing. Remarkably, several native, non-D4Z4–associated, late-replicating telomeres show a preferential localization toward the nuclear periphery, while several early-replicating telomeres are associated with the inner nuclear volume. We propose that, in humans, chromosome arm–specific subtelomeric sequences may influence both the spatial distribution of telomeres in the nucleus and their replication timing. Functional telomeres are essential for genome stability. While replication of telomeres has been extensively studied in model organisms such as the baker's yeast, little is known about the mechanisms that govern the replication of human telomeres. In this study, we have determined the timing of replication of telomeres of individual human chromosomes and its association with potential modulating factors such as particular subtelomeric sequences, the presence of heterochromatic regions, and nuclear localization. We have found that native telomeres associated with D4Z4 sequences—a macrosatellite naturally located in the subtelomeric regions of 4q, 10q, and acrocentric chromosome extremities—replicate later than others. We also present descriptive and experimental evidence indicating that nuclear localization influences the timing of telomere replication. These results contribute to our understanding of telomere metabolism in humans.
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Affiliation(s)
- Nausica Arnoult
- Telomeres and Cancer Laboratory, Institut Curie, CNRS, UPMC University Paris 06, Paris, France
| | - Caroline Schluth-Bolard
- Epigenetics and Telomere Regulation, CNRS ENS UCBL IFR128, Ecole Normale Supérieure de Lyon, Lyon, France
| | - Anne Letessier
- Functional Organization and Plasticity of Mammalian Genomes, Institut Curie, UPMC University Paris 06, Paris, France
| | - Irena Drascovic
- Telomeres and Cancer Laboratory, Institut Curie, CNRS, UPMC University Paris 06, Paris, France
| | | | - Judith Campisi
- Lawrence Berkeley Laboratory, Berkeley, California, United States of America
- Buck Institute for Age Research, Novato, California, United States of America
| | - Sahn-ho Kim
- Lawrence Berkeley Laboratory, Berkeley, California, United States of America
| | - Amina Boussouar
- Epigenetics and Telomere Regulation, CNRS ENS UCBL IFR128, Ecole Normale Supérieure de Lyon, Lyon, France
| | - Alexandre Ottaviani
- Epigenetics and Telomere Regulation, CNRS ENS UCBL IFR128, Ecole Normale Supérieure de Lyon, Lyon, France
| | - Frédérique Magdinier
- Epigenetics and Telomere Regulation, CNRS ENS UCBL IFR128, Ecole Normale Supérieure de Lyon, Lyon, France
| | - Eric Gilson
- Epigenetics and Telomere Regulation, CNRS ENS UCBL IFR128, Ecole Normale Supérieure de Lyon, Lyon, France
| | - Arturo Londoño-Vallejo
- Telomeres and Cancer Laboratory, Institut Curie, CNRS, UPMC University Paris 06, Paris, France
- * E-mail:
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