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Pennarun G, Picotto J, Bertrand P. Close Ties between the Nuclear Envelope and Mammalian Telomeres: Give Me Shelter. Genes (Basel) 2023; 14:genes14040775. [PMID: 37107534 PMCID: PMC10137478 DOI: 10.3390/genes14040775] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Revised: 03/18/2023] [Accepted: 03/20/2023] [Indexed: 04/29/2023] Open
Abstract
The nuclear envelope (NE) in eukaryotic cells is essential to provide a protective compartment for the genome. Beside its role in connecting the nucleus with the cytoplasm, the NE has numerous important functions including chromatin organization, DNA replication and repair. NE alterations have been linked to different human diseases, such as laminopathies, and are a hallmark of cancer cells. Telomeres, the ends of eukaryotic chromosomes, are crucial for preserving genome stability. Their maintenance involves specific telomeric proteins, repair proteins and several additional factors, including NE proteins. Links between telomere maintenance and the NE have been well established in yeast, in which telomere tethering to the NE is critical for their preservation and beyond. For a long time, in mammalian cells, except during meiosis, telomeres were thought to be randomly localized throughout the nucleus, but recent advances have uncovered close ties between mammalian telomeres and the NE that play important roles for maintaining genome integrity. In this review, we will summarize these connections, with a special focus on telomere dynamics and the nuclear lamina, one of the main NE components, and discuss the evolutionary conservation of these mechanisms.
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Affiliation(s)
- Gaëlle Pennarun
- Université Paris Cité, INSERM, CEA, Stabilité Génétique Cellules Souches et Radiations, LREV/iRCM/IBFJ, F-92260 Fontenay-aux-Roses, France
- Université Paris-Saclay, INSERM, CEA, Stabilité Génétique Cellules Souches et Radiations, LREV/iRCM/IBFJ, F-92260 Fontenay-aux-Roses, France
| | - Julien Picotto
- Université Paris Cité, INSERM, CEA, Stabilité Génétique Cellules Souches et Radiations, LREV/iRCM/IBFJ, F-92260 Fontenay-aux-Roses, France
- Université Paris-Saclay, INSERM, CEA, Stabilité Génétique Cellules Souches et Radiations, LREV/iRCM/IBFJ, F-92260 Fontenay-aux-Roses, France
| | - Pascale Bertrand
- Université Paris Cité, INSERM, CEA, Stabilité Génétique Cellules Souches et Radiations, LREV/iRCM/IBFJ, F-92260 Fontenay-aux-Roses, France
- Université Paris-Saclay, INSERM, CEA, Stabilité Génétique Cellules Souches et Radiations, LREV/iRCM/IBFJ, F-92260 Fontenay-aux-Roses, France
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2
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Pennarun G, Picotto J, Etourneaud L, Redavid AR, Certain A, Gauthier LR, Fontanilla-Ramirez P, Busso D, Chabance-Okumura C, Thézé B, Boussin FD, Bertrand P. Increase in lamin B1 promotes telomere instability by disrupting the shelterin complex in human cells. Nucleic Acids Res 2021; 49:9886-9905. [PMID: 34469544 PMCID: PMC8464066 DOI: 10.1093/nar/gkab761] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Revised: 08/04/2021] [Accepted: 08/31/2021] [Indexed: 12/19/2022] Open
Abstract
Telomere maintenance is essential to preserve genomic stability and involves telomere-specific proteins, DNA replication and repair proteins. Lamins are key components of the nuclear envelope and play numerous roles, including maintenance of the nuclear integrity, regulation of transcription, and DNA replication. Elevated levels of lamin B1, one of the major lamins, have been observed in some human pathologies and several cancers. Yet, the effect of lamin B1 dysregulation on telomere maintenance remains unknown. Here, we unveil that lamin B1 overexpression drives telomere instability through the disruption of the shelterin complex. Indeed, lamin B1 dysregulation leads to an increase in telomere dysfunction-induced foci, telomeric fusions and telomere losses in human cells. Telomere aberrations were preceded by mislocalizations of TRF2 and its binding partner RAP1. Interestingly, we identified new interactions between lamin B1 and these shelterin proteins, which are strongly enhanced at the nuclear periphery upon lamin B1 overexpression. Importantly, chromosomal fusions induced by lamin B1 in excess were rescued by TRF2 overexpression. These data indicated that lamin B1 overexpression triggers telomere instability through a mislocalization of TRF2. Altogether our results point to lamin B1 as a new interacting partner of TRF2, that is involved in telomere stability.
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Affiliation(s)
- Gaëlle Pennarun
- Université de Paris and Université Paris-Saclay, INSERM, iRCM/IBFJ CEA, UMR Stabilité Génétique Cellules Souches et Radiations, F-92265 Fontenay-aux-Roses, France
- “DNA Repair and Ageing” Team, iRCM/IBFJ, DRF, CEA, Fontenay-aux-Roses, France
| | - Julien Picotto
- Université de Paris and Université Paris-Saclay, INSERM, iRCM/IBFJ CEA, UMR Stabilité Génétique Cellules Souches et Radiations, F-92265 Fontenay-aux-Roses, France
- “DNA Repair and Ageing” Team, iRCM/IBFJ, DRF, CEA, Fontenay-aux-Roses, France
| | - Laure Etourneaud
- Université de Paris and Université Paris-Saclay, INSERM, iRCM/IBFJ CEA, UMR Stabilité Génétique Cellules Souches et Radiations, F-92265 Fontenay-aux-Roses, France
- “DNA Repair and Ageing” Team, iRCM/IBFJ, DRF, CEA, Fontenay-aux-Roses, France
| | - Anna-Rita Redavid
- Université de Paris and Université Paris-Saclay, INSERM, iRCM/IBFJ CEA, UMR Stabilité Génétique Cellules Souches et Radiations, F-92265 Fontenay-aux-Roses, France
- “DNA Repair and Ageing” Team, iRCM/IBFJ, DRF, CEA, Fontenay-aux-Roses, France
| | - Anaïs Certain
- Université de Paris and Université Paris-Saclay, INSERM, iRCM/IBFJ CEA, UMR Stabilité Génétique Cellules Souches et Radiations, F-92265 Fontenay-aux-Roses, France
- “DNA Repair and Ageing” Team, iRCM/IBFJ, DRF, CEA, Fontenay-aux-Roses, France
| | - Laurent R Gauthier
- Université de Paris and Université Paris-Saclay, INSERM, iRCM/IBFJ CEA, UMR Stabilité Génétique Cellules Souches et Radiations, F-92265 Fontenay-aux-Roses, France
- “Radiopathology” Team, iRCM/IBFJ, DRF, CEA, Fontenay-aux-Roses, France
| | - Paula Fontanilla-Ramirez
- Université de Paris and Université Paris-Saclay, INSERM, iRCM/IBFJ CEA, UMR Stabilité Génétique Cellules Souches et Radiations, F-92265 Fontenay-aux-Roses, France
- “DNA Repair and Ageing” Team, iRCM/IBFJ, DRF, CEA, Fontenay-aux-Roses, France
| | - Didier Busso
- Université de Paris and Université Paris-Saclay, INSERM, iRCM/IBFJ CEA, UMR Stabilité Génétique Cellules Souches et Radiations, F-92265 Fontenay-aux-Roses, France
- Genetic Engineering and Expression Platform (CIGEX), iRCM, DRF, CEA, Fontenay-aux-Roses, France
| | - Caroline Chabance-Okumura
- Université de Paris and Université Paris-Saclay, INSERM, iRCM/IBFJ CEA, UMR Stabilité Génétique Cellules Souches et Radiations, F-92265 Fontenay-aux-Roses, France
- “DNA Repair and Ageing” Team, iRCM/IBFJ, DRF, CEA, Fontenay-aux-Roses, France
| | - Benoît Thézé
- Université de Paris and Université Paris-Saclay, INSERM, iRCM/IBFJ CEA, UMR Stabilité Génétique Cellules Souches et Radiations, F-92265 Fontenay-aux-Roses, France
- “DNA Repair and Ageing” Team, iRCM/IBFJ, DRF, CEA, Fontenay-aux-Roses, France
| | - François D Boussin
- Université de Paris and Université Paris-Saclay, INSERM, iRCM/IBFJ CEA, UMR Stabilité Génétique Cellules Souches et Radiations, F-92265 Fontenay-aux-Roses, France
- “Radiopathology” Team, iRCM/IBFJ, DRF, CEA, Fontenay-aux-Roses, France
| | - Pascale Bertrand
- Université de Paris and Université Paris-Saclay, INSERM, iRCM/IBFJ CEA, UMR Stabilité Génétique Cellules Souches et Radiations, F-92265 Fontenay-aux-Roses, France
- “DNA Repair and Ageing” Team, iRCM/IBFJ, DRF, CEA, Fontenay-aux-Roses, France
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3
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Balzano E, Pelliccia F, Giunta S. Genome (in)stability at tandem repeats. Semin Cell Dev Biol 2020; 113:97-112. [PMID: 33109442 DOI: 10.1016/j.semcdb.2020.10.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Revised: 09/26/2020] [Accepted: 10/10/2020] [Indexed: 12/12/2022]
Abstract
Repeat sequences account for over half of the human genome and represent a significant source of variation that underlies physiological and pathological states. Yet, their study has been hindered due to limitations in short-reads sequencing technology and difficulties in assembly. A important category of repetitive DNA in the human genome is comprised of tandem repeats (TRs), where repetitive units are arranged in a head-to-tail pattern. Compared to other regions of the genome, TRs carry between 10 and 10,000 fold higher mutation rate. There are several mutagenic mechanisms that can give rise to this propensity toward instability, but their precise contribution remains speculative. Given the high degree of homology between these sequences and their arrangement in tandem, once damaged, TRs have an intrinsic propensity to undergo aberrant recombination with non-allelic exchange and generate harmful rearrangements that may undermine the stability of the entire genome. The dynamic mutagenesis at TRs has been found to underlie individual polymorphism associated with neurodegenerative and neuromuscular disorders, as well as complex genetic diseases like cancer and diabetes. Here, we review our current understanding of the surveillance and repair mechanisms operating within these regions, and we describe how alterations in these protective processes can readily trigger mutational signatures found at TRs, ultimately resulting in the pathological correlation between TRs instability and human diseases. Finally, we provide a viewpoint to counter the detrimental effects that TRs pose in light of their selection and conservation, as important drivers of human evolution.
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Affiliation(s)
- Elisa Balzano
- Dipartimento di Biologia e Biotecnologie "Charles Darwin", Sapienza Università di Roma, 00185 Roma, Italy
| | - Franca Pelliccia
- Dipartimento di Biologia e Biotecnologie "Charles Darwin", Sapienza Università di Roma, 00185 Roma, Italy
| | - Simona Giunta
- The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA; Dipartimento di Biologia e Biotecnologie "Charles Darwin", Sapienza Università di Roma, 00185 Roma, Italy.
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4
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Shishkin SS, Kovalev LI, Pashintseva NV, Kovaleva MA, Lisitskaya K. Heterogeneous Nuclear Ribonucleoproteins Involved in the Functioning of Telomeres in Malignant Cells. Int J Mol Sci 2019; 20:ijms20030745. [PMID: 30744200 PMCID: PMC6387250 DOI: 10.3390/ijms20030745] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2018] [Revised: 01/31/2019] [Accepted: 02/04/2019] [Indexed: 12/12/2022] Open
Abstract
Heterogeneous nuclear ribonucleoproteins (hnRNPs) are structurally and functionally distinct proteins containing specific domains and motifs that enable the proteins to bind certain nucleotide sequences, particularly those found in human telomeres. In human malignant cells (HMCs), hnRNP-A1-the most studied hnRNP-is an abundant multifunctional protein that interacts with telomeric DNA and affects telomerase function. In addition, it is believed that other hnRNPs in HMCs may also be involved in the maintenance of telomere length. Accordingly, these proteins are considered possible participants in the processes associated with HMC immortalization. In our review, we discuss the results of studies on different hnRNPs that may be crucial to solving molecular oncological problems and relevant to further investigations of these proteins in HMCs.
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Affiliation(s)
- Sergey S Shishkin
- Laboratory of Biomedical Research, Bach Institute of Biochemistry, Research Center of Biotechnology of the Russian Academy of Sciences, Leninsky Prospekt, 33, bld. 2, 119071 Moscow, Russia.
| | - Leonid I Kovalev
- Laboratory of Biomedical Research, Bach Institute of Biochemistry, Research Center of Biotechnology of the Russian Academy of Sciences, Leninsky Prospekt, 33, bld. 2, 119071 Moscow, Russia.
| | - Natalya V Pashintseva
- Laboratory of Biomedical Research, Bach Institute of Biochemistry, Research Center of Biotechnology of the Russian Academy of Sciences, Leninsky Prospekt, 33, bld. 2, 119071 Moscow, Russia.
| | - Marina A Kovaleva
- Laboratory of Biomedical Research, Bach Institute of Biochemistry, Research Center of Biotechnology of the Russian Academy of Sciences, Leninsky Prospekt, 33, bld. 2, 119071 Moscow, Russia.
| | - Ksenia Lisitskaya
- Laboratory of Biomedical Research, Bach Institute of Biochemistry, Research Center of Biotechnology of the Russian Academy of Sciences, Leninsky Prospekt, 33, bld. 2, 119071 Moscow, Russia.
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5
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Abstract
Chromosome ends are complex structures, which require a panel of factors for their elongation, replication, and protection. We describe here the mechanics of mammalian telomeres, dynamics and maintainance in relation to lamins. Multiple biochemical connections, including association of telomeres to the nuclear envelope and matrix, of telomeric proteins to lamins, and of lamin-associated proteins to chromosome ends, underline the interplay between lamins and telomeres. Paths toward senescence, such as defective telomere replication, altered heterochromatin organization, and impaired DNA repair, are common to lamins' and telomeres' dysfunction. The convergence of phenotypes can be interpreted through a model of dynamic, lamin-controlled functional platforms dedicated to the function of telomeres as fragile sites. The features of telomeropathies and laminopathies, and of animal models underline further overlapping aspects, including the alteration of stem cell compartments. We expect that future studies of basic biology and on aging will benefit from the analysis of this telomere-lamina interplay.
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Affiliation(s)
- Romina Burla
- a Dipartimento di Biologia e Biotecnologie "C. Darwin," Sapienza Università di Roma , Rome, Italy.,b Istituto di Biologia e Patologia Molecolari del CNR , Rome , Italy
| | - Mattia La Torre
- a Dipartimento di Biologia e Biotecnologie "C. Darwin," Sapienza Università di Roma , Rome, Italy
| | - Isabella Saggio
- a Dipartimento di Biologia e Biotecnologie "C. Darwin," Sapienza Università di Roma , Rome, Italy.,b Istituto di Biologia e Patologia Molecolari del CNR , Rome , Italy.,c Istituto Pasteur Fondazione Cenci Bolognetti , Rome , Italy
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6
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Mandrioli M, Bandinelli S, Manicardi GC. Occurrence of Rabl-like telomere clustering in the holocentric chromosomes of the peach potato aphid Myzus persicae (Hemiptera; Aphididae). Cytogenet Genome Res 2014; 144:68-75. [PMID: 25277538 DOI: 10.1159/000366049] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/12/2014] [Indexed: 11/19/2022] Open
Abstract
Several studies demonstrated that chromosome anchoring to nuclear structures is involved in the organization of the interphase nucleus. The Rabl configuration, a well-studied chromosome organization in the interphase nucleus, has been deeply studied in organisms with monocentric chromosomes but just slightly touched in species with holocentric chromosomes. In the present paper, by means of the isolation and chromosomal mapping of the C0t DNA fraction and chromatin immunoprecipitation with anti-LEM-2 antibodies, we evidenced the presence of few foci where telomeres and subtelomeric regions cluster in the aphid interphase nuclei, suggesting the occurrence of a Rabl-like chromosome configuration. The same experimental approaches also evidenced that most of the repetitive DNA of the 2 X chromosomes is located at the periphery of the nucleus, whereas the ribosomal genes, located at 1 telomere of each X chromosome, are present towards the inner portion of the nucleus, favoring their transcriptional activity.
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Affiliation(s)
- Mauro Mandrioli
- Dipartimento di Scienze della Vita, Università di Modena e Reggio Emilia, Modena, Italy
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7
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Wang Y, Xu C, Liang Y, Vanhoutte PM. SIRT1 in metabolic syndrome: where to target matters. Pharmacol Ther 2012; 136:305-18. [PMID: 22939883 DOI: 10.1016/j.pharmthera.2012.08.009] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2012] [Accepted: 08/07/2012] [Indexed: 12/28/2022]
Abstract
Sirtuin 1 (SIRT1), the mammalian ortholog of yeast Sir2p, is a highly conserved NAD(+)-dependent protein deacetylase that has emerged as a key cardiometabolic regulator. During the past decade, Sir2p has been the focus of intense investigations and discussion because it regulates longevity in yeast, worms and flies. Although the extrapolation of data obtained from yeast Sir2p to mammalian SIRT1 cannot be automatic, animal studies provide convincing evidence that SIRT1 is a potent protector against aging-associated pathologies, in particular metabolic disorders and cardiovascular diseases. Indeed, many exciting connections exist between the protein deacetylation function of SIRT1 and its role in fundamental biological responses to various nutritional and environmental signals. As a result, pharmaceutical and nutriceutical interventions targeting SIRT1 are promising strategies to combat aging-associated diseases. The present review summarizes the recent progress in SIRT1 research with a particular focus on the specificities of this protein in individual tissues as they relate to cardiometabolic control.
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Affiliation(s)
- Yu Wang
- Department of Pharmacology and Pharmacy, LKS Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong, China.
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8
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Schubert I, Shaw P. Organization and dynamics of plant interphase chromosomes. TRENDS IN PLANT SCIENCE 2011; 16:273-81. [PMID: 21393049 DOI: 10.1016/j.tplants.2011.02.002] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2010] [Revised: 02/01/2011] [Accepted: 02/05/2011] [Indexed: 05/23/2023]
Abstract
Eukaryotic chromosomes occupy distinct territories within interphase nuclei. The arrangement of chromosome territories (CTs) is important for replication, transcription, repair and recombination processes. Our knowledge about interphase chromatin arrangement is mainly based on results from in situ labeling approaches. The phylogenetic affiliation of a species, cell cycle, differentiation status and environmental factors are all likely to influence interphase nuclear architecture. In this review we survey current data about relative positioning of CTs, somatic pairing of homologs, and sister chromatid alignment in meristematic and differentiated tissues, using data derived mainly from Arabidopsis thaliana, wheat (Triticum aestivum) and their relatives. We discuss morphological constraints and epigenetic impacts on nuclear architecture, the evolutionary stability of CT arrangements, and alterations of nuclear architecture during transcription and repair.
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Affiliation(s)
- Ingo Schubert
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Corrensstrasse 3, D06466 Gatersleben, Germany.
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Abstract
RÉSUMÉ:Des mécanismes moléculaires liant le cancer à la sénescence cellulaire sont présentement explorés. Les télomères (l'extrémité des chromosomes) raccourcissent à chaque division cellulaire et il a été proposé que ce raccourcissement soit l'horloge moléculaire qui déclenche le processus de la sénescence cellulaire. La re-expression de la télomérase, une enzyme qui aide à maintenir la longueur des télomères et à prévenir leur raccourcissement, est un événement fréquemment observé dans les cellules tumorales. Cette re-expression est probablement essentielle à la formation et à la croissance soutenue de la majorité des cancers.
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Giraud-Panis MJ, Pisano S, Poulet A, Le Du MH, Gilson E. Structural identity of telomeric complexes. FEBS Lett 2010; 584:3785-99. [PMID: 20696167 DOI: 10.1016/j.febslet.2010.08.004] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2010] [Revised: 08/02/2010] [Accepted: 08/02/2010] [Indexed: 02/01/2023]
Abstract
A major issue in telomere research is to understand how the integrity of chromosome ends is controlled. Although several nucleoprotein complexes have been described at the telomeres of different organisms, it is still unclear how they confer a structural identity to chromosome ends in order to mask them from DNA repair and to ensure their proper replication. In this review, we describe how telomeric nucleoprotein complexes are structured, comparing different organisms and trying to link these structures to telomere biology. It emerges that telomeres are formed by a complex and specific network of interactions between DNA, RNA and proteins. The fact that these interactions and associated activities are reinforcing each other might help to guaranty the robustness of telomeric functions across the cell cycle and in the event of cellular perturbations. We propose that telomeric nucleoprotein complexes orient cell fate through dynamic transitions in their structures and their organization.
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Affiliation(s)
- Marie-Josèphe Giraud-Panis
- University de Nice, Laboratory of Biology and Pathology of Genomes, UMR 6267 CNRS U998 INSERM, Faculté de Médecine, Nice, France
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Identification of a perinuclear positioning element in human subtelomeres that requires A-type lamins and CTCF. EMBO J 2009; 28:2428-36. [PMID: 19644448 DOI: 10.1038/emboj.2009.201] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2009] [Accepted: 06/23/2009] [Indexed: 11/08/2022] Open
Abstract
The localization of genes within the nuclear space is of paramount importance for proper genome functions. However, very little is known on the cis-acting elements determining subnuclear positioning of chromosome segments. We show here that the D4Z4 human subtelomeric repeat localizes a telomere at the nuclear periphery. This perinuclear activity lies within an 80 bp sequence included within a region known to interact with CTCF and A-type Lamins. We further show that a reduced level of either CTCF or A-type Lamins suppresses the perinuclear activities of D4Z4 and that an array of multimerized D4Z4 sequence, which has lost its ability to bind CTCF and A-type Lamins, is not localized at the periphery. Overall, these findings reveal the existence of an 80 bp D4Z4 sequence that is sufficient to position an adjacent telomere to the nuclear periphery in a CTCF and A-type lamins-dependent manner. Strikingly, this sequence includes a 30 bp GA-rich motif, which binds CTCF and is present at several locations in the human genome.
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12
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Byrne RD, Poccia DL, Larijani B. Role of phospholipase C in nuclear envelope assembly. ACTA ACUST UNITED AC 2009. [DOI: 10.2217/17584299.4.1.103] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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13
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Kondo Y, Shen L, Ahmed S, Boumber Y, Sekido Y, Haddad BR, Issa JPJ. Downregulation of histone H3 lysine 9 methyltransferase G9a induces centrosome disruption and chromosome instability in cancer cells. PLoS One 2008; 3:e2037. [PMID: 18446223 PMCID: PMC2323574 DOI: 10.1371/journal.pone.0002037] [Citation(s) in RCA: 203] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2007] [Accepted: 03/10/2008] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Modifications of the histone amino-terminal tails affect access of regulatory factors and complexes to chromatin and thereby influence biological processes. Cancer cells are characterized by prominent epigenetic dysregulation, including histone modifications. However, the functional roles of the histone methyltransferases (HMT) in cancer remain unclear. METHODOLOGY/PRINCIPAL FINDINGS We studied RNAi-based inhibition (knockdown, KD) of 2 different H3K9 HMTs, SUV39H1 and G9a. Knockdown of the 2 HMTs in PC3 cancer cell line markedly inhibited cell growth and caused profound morphological changes with loss of telomerase activity and shortened telomeres. SUV39H1 KD cells showed substantial increase in G2/M fraction. G9a KD cells showed increased DNA content (1.7-fold in 2 independent clones) compared with FACS analyses to control. Karyotype analyses showed that this was due to an increased number of chromosomes (from 61 to 102) in G9a KD cells compared to parental PC3. Intriguingly, we found abnormal centrosome morphology and number in about 25% of the G9a KD cells, while centrosomes were morphologically normal in control cells. Microarray analyses after KD of SUV39H1 or G9a showed very few genes up-regulated among the 39,000 genes. The silenced tumor-suppressor genes p16 and RASSF1A were not activated in KD cells. CONCLUSIONS/SIGNIFICANCE These data suggest that the 2 HMTs, SUV39H1 and G9a are required to perpetuate the malignant phenotype. Furthermore, G9a plays a critical role in regulating centrosome duplication presumably through chromatin structure rather than through affecting gene expression in cancer cells. Targeting these histone methyltransferases may be of therapeutic benefit in cancers.
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Affiliation(s)
- Yutaka Kondo
- Division of Molecular Oncology, Aichi Cancer Center Research Institute, Nagoya, Japan.
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Yeast Est2p affects telomere length by influencing association of Rap1p with telomeric chromatin. Mol Cell Biol 2008; 28:2380-90. [PMID: 18212041 DOI: 10.1128/mcb.01648-07] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In Saccharomyces cerevisiae, the sequence-specific binding of the negative regulator Rap1p provides a mechanism to measure telomere length: as the telomere length increases, the binding of additional Rap1p inhibits telomerase activity in cis. We provide evidence that the association of Rap1p with telomeric DNA in vivo occurs in part by sequence-independent mechanisms. Specific mutations in EST2 (est2-LT) reduce the association of Rap1p with telomeric DNA in vivo. As a result, telomeres are abnormally long yet bind an amount of Rap1p equivalent to that observed at wild-type telomeres. This behavior contrasts with that of a second mutation in EST2 (est2-up34) that increases bound Rap1p as expected for a strain with long telomeres. Telomere sequences are subtly altered in est2-LT strains, but similar changes in est2-up34 telomeres suggest that sequence abnormalities are a consequence, not a cause, of overelongation. Indeed, est2-LT telomeres bind Rap1p indistinguishably from the wild type in vitro. Taken together, these results suggest that Est2p can directly or indirectly influence the binding of Rap1p to telomeric DNA, implicating telomerase in roles both upstream and downstream of Rap1p in telomere length homeostasis.
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Zhdanova NS, Rubtsov NB, Minina YM. Terminal regions of mammal chromosomes: Plasticity and role in evolution. RUSS J GENET+ 2007. [DOI: 10.1134/s1022795407070022] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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16
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Berthiau AS, Yankulov K, Bah A, Revardel E, Luciano P, Wellinger RJ, Géli V, Gilson E. Subtelomeric proteins negatively regulate telomere elongation in budding yeast. EMBO J 2006; 25:846-56. [PMID: 16467854 PMCID: PMC1383556 DOI: 10.1038/sj.emboj.7600975] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2005] [Accepted: 01/09/2006] [Indexed: 11/09/2022] Open
Abstract
The Tbf1 and Reb1 proteins are present in yeast subtelomeric regions. We establish in this work that they inhibit telomerase-dependent lengthening of telomere. For example, tethering the N-terminal domain of Tbf1 and Reb1 in a subtelomeric region shortens that telomere proportionally to the number of domains bound. We further identified a 90 amino-acid long sequence within the N-terminal domain of Tbf1 that is necessary but not sufficient for its length regulation properties. The role of the subtelomeric factors in telomere length regulation is antagonized by TEL1 and does not correlate with a global telomere derepression. We show that the absence of TEL1 induces an alteration in the structure of telomeric chromatin, as defined biochemically by an increased susceptibility to nucleases and a greater heterogeneity of products. We propose that the absence of TEL1 modifies the organization of the telomeres, which allows Tbf1 and Reb1 to cis-inhibit telomerase. The involvement of subtelomeric factors in telomere length regulation provides a possible mechanism for the chromosome-specific length setting observed at yeast and human telomeres.
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Affiliation(s)
- Anne-Sophie Berthiau
- Laboratoire de Biologie Moléculaire de la Cellule de l'Ecole Normale Supérieure de Lyon, CNRS UMR5161, IFR 128, Lyon, France
| | - Krassimir Yankulov
- Laboratoire de Biologie Moléculaire de la Cellule de l'Ecole Normale Supérieure de Lyon, CNRS UMR5161, IFR 128, Lyon, France
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - Amadou Bah
- Laboratoire de Biologie Moléculaire de la Cellule de l'Ecole Normale Supérieure de Lyon, CNRS UMR5161, IFR 128, Lyon, France
- Department of Microbiology and Infectious Diseases, Faculty of Medicine, Universite de Sherbrooke 3001, Sherbrooke, Quebec, Canada
| | - Emmanuelle Revardel
- Laboratoire de Biologie Moléculaire de la Cellule de l'Ecole Normale Supérieure de Lyon, CNRS UMR5161, IFR 128, Lyon, France
| | - Pierre Luciano
- Laboratoire d'Instabilité Génétique et Cancérogenèse (IGC), CNRS, Marseille, France
| | - Raymund J Wellinger
- Department of Microbiology and Infectious Diseases, Faculty of Medicine, Universite de Sherbrooke 3001, Sherbrooke, Quebec, Canada
| | - Vincent Géli
- Laboratoire d'Instabilité Génétique et Cancérogenèse (IGC), CNRS, Marseille, France
| | - Eric Gilson
- Laboratoire de Biologie Moléculaire de la Cellule de l'Ecole Normale Supérieure de Lyon, CNRS UMR5161, IFR 128, Lyon, France
- Laboratoire de Biologie Moléculaire et Cellulaire, Ecole Normale Supérieure, UMR5161 CNRS/ENSL, 46 Allee d'italie, 69364 Lyon Cedex 07, France. Tel.: +33 472 728 453; Fax: +33 472 728 686; E-mail:
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17
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Michelson RJ, Rosenstein S, Weinert T. A telomeric repeat sequence adjacent to a DNA double-stranded break produces an anticheckpoint. Genes Dev 2005; 19:2546-59. [PMID: 16230525 PMCID: PMC1276729 DOI: 10.1101/gad.1293805] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Telomeres are complex structures that serve to protect chromosome ends. Here we provide evidence that in Saccharomyces cerevisiae telomeres may contain an anticheckpoint activity that prevents chromosome ends from signaling cell cycle arrest. We found that an internal tract of telomeric repeats inhibited DNA damage checkpoint signaling from adjacent double-strand breaks (DSBs); cell cycle arrest lasted 8-12 h from a normal DSB, whereas it lasted only 1-2 h from a DSB adjacent to a telomeric repeat. The shortened or abridged arrest was not the result of DNA repair, nor reduced amounts of single-stranded DNA, nor of adaptation. The molecular identity of this telomere repeat-associated anticheckpoint activity is unknown, though it is not dependent upon telomerase or telomere-proximal gene silencing. The anticheckpoint may inhibit the ATR yeast ortholog Mec1 because Rad9 and Rad53 became dephosphorylated and inactivated during the abridged arrest. The anticheckpoint acts regionally; it inhibited signaling from DNA breaks up to 0.6 kb away from the telomeric repeat but not from a DSB present on a separate chromosome. We propose that after formation of the DSB near the telomeric repeat, a mature telomere forms in 1-2 h, and the telomere then contains proteins that inhibit checkpoint signaling from nearby DNA breaks.
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Affiliation(s)
- Rhett J Michelson
- Molecular and Cellular Biology Department, University of Arizona, Tucson, Arizona 85721, USA
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18
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Meerdo LN, Reed WA, White KL. Telomere-to-centromere ratio of bovine clones, embryos, gametes, fetal cells, and adult cells. CLONING AND STEM CELLS 2005; 7:62-73. [PMID: 15996118 DOI: 10.1089/clo.2005.7.62] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
In 1997, Dolly, the first animal cloned from an adult cell, was born. It was announced in 1999 that Dolly might be aging faster than normal because her telomeres were shorter than age-matched control sheep. Telomeres, a repeated DNA sequence located at the ends of linear chromosomes, allow for base pair loss during DNA replication. Telomere shortening acts as a "mitotic clock," leading to replicative senescence. By using whole cell lysate and slot-blot analysis, we determined the telomere-to-centromere ratio (T/C) for bovine gametes, embryos, fetal tissues (brain, heart, lung, kidney, uterus, ovary, and skin), adult donor cells, and cloned embryos. Our data indicates a consistency in T/C among the various fetal tissues. The T/C of sperm is significantly lower than in oocytes. The T/C decreases from the oocyte to the 2-8-cell stage embryo, increases dramatically at the morula stage, and decreases at the blastocyst stage. Our data shows no significant difference in T/C between cloned embryos and in vitro fertilized (IVF) embryos, but there is a significant difference between cloned embryos and adult donor cells. In conclusion, the enucleated bovine oocyte has the ability to reestablish the telomere length of adult somatic cell donor nuclei.
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Affiliation(s)
- Lora N Meerdo
- Department of Animal, Dairy and Veterinary Sciences, Utah State University, 4815 Old Main Hill, Logan, UT 84322, USA
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19
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Tolstonog GV, Li G, Shoeman RL, Traub P. Interaction in vitro of type III intermediate filament proteins with higher order structures of single-stranded DNA, particularly with G-quadruplex DNA. DNA Cell Biol 2005; 24:85-110. [PMID: 15699629 DOI: 10.1089/dna.2005.24.85] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Cytoplasmic intermediate filament (cIF) proteins interact strongly with single-stranded (ss) DNAs and RNAs, particularly with G-rich sequences. To test the hypothesis that this interaction depends on special nucleotide sequences and, possibly, higher order structures of ssDNA, a random mixture of mouse genomic ssDNA fragments generated by a novel "whole ssDNA genome PCR" technique via RNA intermediates was subjected to three rounds of affinity binding to in vitro reconstituted vimentin IFs at physiological ionic strength with intermediate PCR amplification of the bound ssDNA segments. Nucleotide sequence and computer folding analysis of the vimentin-selected fragments revealed an enrichment in microsatellites, predominantly of the (GT)n type, telomere DNA, and C/T-rich sequences, most of which, however, were incapable of folding into stable stem-loop structures. Because G-rich sequences were underrepresented in the vimentin-bound fraction, it had to be assumed that such sequences require intramolecular folding or lateral assembly into multistrand structures to be able to stably interact with vimentin, but that this requirement was inadequately fulfilled under the conditions of the selection experiment. For that reason, the few vimentin-selected G-rich ssDNA fragments and a number of telomere models were analyzed for their capacity to form inter- and intramolecular Gquadruplexes (G4 DNAs) under optimized conditions and to interact as such with vimentin and its type III relatives, glial fibrillary acidic protein, and desmin. Band shift assays indeed demonstrated differential binding of the cIF proteins to parallel four-stranded G4 DNAs and, with lower affinity, to bimolecular G'2 and unimolecular G'4 DNA configurations, whereby the transition regions from four- to single-strandedness played an additional role in the binding reaction. In this respect, the binding activity of cIF proteins was comparable with that toward other noncanonical DNA structures, like ds/ss DNA forks, triplex DNA, four-way junction DNA and Z-DNA, which also involve configurational transitions in their interaction with the filament proteins. Association of the cIF proteins with the corresponding nonfolded G-rich ssDNAs was negligible. Considering the almost universal involvement of ssDNA regions and G-quadruplexes in nuclear processes, including DNA transcription and recombination as well as telomere maintenance and dynamics, it is plausible to presume that cIF proteins as complementary constituents of the nuclear matrix participate in the cell- and tissue-specific regulation of these processes.
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20
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Voronin AP, Lobov IB, Gilson E, Podgornaya OI. A telomere-binding protein (TRF2/MTBP) from mouse nuclear matrix with motives of an intermediate filament-type rod domain. ACTA ACUST UNITED AC 2004; 6:205-18. [PMID: 14987434 DOI: 10.1089/109454503322733054] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
In previous work, we identified a telomeric DNA-binding protein (termed telomere-membrane binding protein, MTBP) in the envelope of the frog oocyte nucleus and raised antibodies against it. Here we present immunological evidence which suggests strongly that MTBP is identical with the vertebrate telomeric DNA-binding protein TRF2 (telomere-repeat factor 2). MTBP/TRF2 possesses motif which resembles rod domain characteristic of intermediate filament (IF) proteins as shown by immunological cross-reactivity with characteristic antibodies, as well as amino acid sequence homology. Anti-MTBP antibodies recognised a protein of the same M, as TRF2 in extracts of mouse nuclei and nuclear matrix as shown by ion-exchange chromatography, gel shift assays, and Western blots. This mouse MTBP analogue forms more stable complexes with the vertebrate telomeric DNA fragment (T(2)AG(3))(135) than with the corresponding fragment from Tetrahymena (T(2)G(4))(130). Proteins in each of these complexes are recognised by anti-MTBP antibody. In situ hybridization with the vertebrate telomeric DNA sequence (T(2)AG(3))(135) and immunofluorescence with anti-MTBP antibody had shown earlier that these are co-localised in the nucleus of mouse cells, and here MTBP is shown to be associated with the residual membrane of hepatocyte nuclei using Western blotting and immunofluorescence. Some immunofluorescence signal from MTBP is localized at chromosome extremities on metaphase plates from mouse cell culture, but the main signal is seen in patches scattered around the chromosomes which were identified as remnants of the nuclear envelope by double labelling with antibodies against lamin B. These observations suggest that MTBP/TRF2 is a good candidate for the attachment of telomeres to the nuclear envelope in somatic cells.
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Affiliation(s)
- Alexey P Voronin
- Institute of Cytology, Russian Academy of Sciences, St. Petersburg, Russia
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21
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Wickstead B, Ersfeld K, Gull K. Repetitive elements in genomes of parasitic protozoa. Microbiol Mol Biol Rev 2003; 67:360-75, table of contents. [PMID: 12966140 PMCID: PMC193867 DOI: 10.1128/mmbr.67.3.360-375.2003] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Repetitive DNA elements have been a part of the genomic fauna of eukaryotes perhaps since their very beginnings. Millions of years of coevolution have given repeats central roles in chromosome maintenance and genetic modulation. Here we review the genomes of parasitic protozoa in the context of the current understanding of repetitive elements. Particular reference is made to repeats in five medically important species with ongoing or completed genome sequencing projects: Plasmodium falciparum, Leishmania major, Trypanosoma brucei, Trypanosoma cruzi, and Giardia lamblia. These organisms are used to illustrate five thematic classes of repeats with different structures and genomic locations. We discuss how these repeat classes may interact with parasitic life-style and also how they can be used as experimental tools. The story which emerges is one of opportunism and upheaval which have been employed to add genetic diversity and genomic flexibility.
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Affiliation(s)
- Bill Wickstead
- Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, United Kingdom
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22
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Yamamoto Y, Fujimoto Y, Arai R, Fujie M, Usami S, Yamada T. Retrotransposon-mediated restoration of Chlorella telomeres: accumulation of Zepp retrotransposons at termini of newly formed minichromosomes. Nucleic Acids Res 2003; 31:4646-53. [PMID: 12888526 PMCID: PMC169880 DOI: 10.1093/nar/gkg490] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
To elucidate the contribution of LINE-like retrotransposon Zepp elements to the formation and maintenance of chromosomal telomeres, newly formed minichromosomes in irradiated Chlorella vulgaris cells were isolated and structurally characterized. A minichromosome (miniV4) of approximately 700 kb in size contained a Zepp cluster taking the place of the telomeric repeats on one terminus, whereas the other end of this chromosome consisted of canonical telomeric repeats. The Zepp copies in this cluster were in a tandem array with their poly(A) tails towards the centromere. Another minichromosome Y32 ( approximately 400 kb in size) was shown to have several copies of Zepp elements on both termini. On the right arm terminus, two copies of Zepp were found in a tandem array with poly(A) tracts facing towards the chromosomal end. The poly(A) tail and the 3'-end of approximately 400 bp of the distal copy were replaced by the telomeric repeats. On the 5'-side of the proximal copy was another Zepp element in the reverse orientation. These newly formed telomeric structures are very similar to those previously found in the left arm of chromosome I and the terminus of an unidentified chromosome and support the model of Zepp-mediated restoration and maintenance of Chlorella telomeres.
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Affiliation(s)
- Yoshitaka Yamamoto
- Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8530, Japan
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23
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Brevet V, Berthiau AS, Civitelli L, Donini P, Schramke V, Géli V, Ascenzioni F, Gilson E. The number of vertebrate repeats can be regulated at yeast telomeres by Rap1-independent mechanisms. EMBO J 2003; 22:1697-706. [PMID: 12660175 PMCID: PMC152899 DOI: 10.1093/emboj/cdg155] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
The number of telomeric DNA repeats at chromosome ends is maintained around a mean value by a dynamic balance between elongation and shortening. In particular, proteins binding along the duplex part of telomeric DNA set the number of repeats by progressively limiting telomere growth. The paradigm of this counting mechanism is the Rap1 protein in Saccharomyces cerevisiae. We demonstrate here that a Rap1-independent mechanism regulates the number of yeast telomeric repeats (TG(1-3)) and of vertebrate repeats (T(2)AG(3)) when TEL1, a yeast ortholog of the human gene encoding the ATM kinase, is inactivated. In addition, we show that a T(2)AG(3)-only telomere can be formed and maintained in humanized yeast cells carrying a template mutation of the gene encoding the telomerase RNA, which leads to the synthesis of vertebrate instead of yeast repeats. Genetic and biochemical evidences indicate that this telomere is regulated in a Rap1-independent manner, both in TEL1 and in tel1Delta humanized yeast cells. Altogether, these findings shed light on multiple repeat-counting mechanisms, which may share critical features between lower and higher eukaryotes.
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Affiliation(s)
- Vanessa Brevet
- Laboratoire de Biologie Moléculaire de la Cellule, UMR5665, Centre National de la Recherche Scientifique, Ecole Normale Supérieure de Lyon, 46 Allée d'Italie, 69364 Lyon Cedex 07, France
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24
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Zalenskaya IA, Zalensky AO. Telomeres in mammalian male germline cells. INTERNATIONAL REVIEW OF CYTOLOGY 2003; 218:37-67. [PMID: 12199519 DOI: 10.1016/s0074-7696(02)18011-9] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Telomeres are terminal chromosomal domains that protect chromosome ends from degradation and fusion and promote complete replication of DNA. Telomeres are involved in the regulation of cellular replicative lifespan and tumorigenesis. These important functions of the telomeres have evoked high interest: numerous studies have resulted in a detailed description of telomere composition and structure in somatic cells. Much less is known about telomeres in germline cells. Emerging novel features and unique behavior of telomeres in the process of gamete differentiation suggest that they may have additional germline-specific function(s). This review describes recent studies revealing changes in the telomere organization in the course of differentiation from the germline stem cells to mature sperm in mammals. Similarities and differences between somatic and spermatogenic cells in telomere nuclear localization, protein composition, DNA length, telomerase activity, and chromatin structure are discussed. The exceptional features of the germline telomeres may be important for regulation of telomerase activity during spermatogenesis, homologous chromosome pairing during recombination, as well as for male pronucleus development and ordered chromosome withdrawal post-fertilization.
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Affiliation(s)
- Irina A Zalenskaya
- Department of Biological Chemistry, School of Medicine, University of California, Davis 95616, USA
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25
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Koering CE, Pollice A, Zibella MP, Bauwens S, Puisieux A, Brunori M, Brun C, Martins L, Sabatier L, Pulitzer JF, Gilson E. Human telomeric position effect is determined by chromosomal context and telomeric chromatin integrity. EMBO Rep 2002; 3:1055-61. [PMID: 12393752 PMCID: PMC1307600 DOI: 10.1093/embo-reports/kvf215] [Citation(s) in RCA: 124] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
We investigated the influence of telomere proximity and composition on the expression of an EGFP reporter gene in human cells. In transient transfection assays, telomeric DNA does not repress EGFP but rather slightly increases its expression. In contrast, in stable cell lines, the same reporter construct is repressed when inserted at a subtelomeric location. The telomeric repression is transiently alleviated by increasing the dosage of the TTAGGG repeat factor 1 (TRF1). Upon a prolongated treatment with trichostatin A, the derepression of the subtelomeric reporter gene correlates with the delocalization of HP1alpha and HP1beta. In contrast, treating the cells with 5 azacytidin, a demethylating agent, or with sirtinol, an inhibitor of the Sir2 family of deacetylase, has no apparent effect on telomeric repression. Overall, position effects at human chromosome ends are dependent on a specific higher-order organization of the telomeric chromatin. The possible involvement of HP1 isoforms is discussed.
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Affiliation(s)
- Catherine Elaine Koering
- Laboratoire de Biologie Moléculaire et Cellulaire, UMR5665, Centre National de la Recherche Scientifique, Ecole Normale Supérieure de Lyon, 46 Allée d'Italie, 69364 Lyon cedex 07, France
| | - Alessandra Pollice
- Università degli Studi di Napoli Federico II, Dipartimento di Genetica, Biologia Generale e Molecolare, via Mezzocannone 8, 80134 Naples Italy
- IIGB (International Institute of Genetics and Biophysics), via Marconi 12, 80100 Naples, Italy
- Tel: +33 4 72728453; Fax: +33 4 72728080; or
| | - Maria Pia Zibella
- Università degli Studi di Napoli Federico II, Dipartimento di Genetica, Biologia Generale e Molecolare, via Mezzocannone 8, 80134 Naples Italy
| | - Serge Bauwens
- Unite d'Oncologie Moleculaire, Centre Leon Berard, 28 rue Laennec, 69373 Lyon cedex 08, France
| | - Alain Puisieux
- Unite d'Oncologie Moleculaire, Centre Leon Berard, 28 rue Laennec, 69373 Lyon cedex 08, France
| | - Michele Brunori
- Laboratoire de Biologie Moléculaire et Cellulaire, UMR5665, Centre National de la Recherche Scientifique, Ecole Normale Supérieure de Lyon, 46 Allée d'Italie, 69364 Lyon cedex 07, France
| | - Christine Brun
- Laboratoire de Biologie Moléculaire et Cellulaire, UMR5665, Centre National de la Recherche Scientifique, Ecole Normale Supérieure de Lyon, 46 Allée d'Italie, 69364 Lyon cedex 07, France
| | - Luis Martins
- CEA (Commissariat a l'Energie Atomique), Laboratoire de Radiobiologie et Oncologie, BP6, Fontenay-aux-Roses, France
| | - Laure Sabatier
- CEA (Commissariat a l'Energie Atomique), Laboratoire de Radiobiologie et Oncologie, BP6, Fontenay-aux-Roses, France
| | - John F. Pulitzer
- Università degli Studi di Napoli Federico II, Dipartimento di Genetica, Biologia Generale e Molecolare, via Mezzocannone 8, 80134 Naples Italy
- IIGB (International Institute of Genetics and Biophysics), via Marconi 12, 80100 Naples, Italy
| | - Eric Gilson
- Laboratoire de Biologie Moléculaire et Cellulaire, UMR5665, Centre National de la Recherche Scientifique, Ecole Normale Supérieure de Lyon, 46 Allée d'Italie, 69364 Lyon cedex 07, France
- Tel: +33 4 72728453; Fax: +33 4 72728080; or
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26
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Abstract
Accumulation of DNA damage has been associated with the onset of senescence and predisposition to cancer. The gene responsible for ataxia telangiectasia (A-T) is ATM (ataxia-telangiectasia mutant), a master controller of cellular pathways and networks, orchestrating the responses to a specific type of DNA damage: the double strand break. Based on the homology of the human ATM gene to the TEL1, MEC1 and rad3 genes of yeast, it has now been demonstrated that mutations in ATM lead to defective telomere maintenance in mammalian cells. While ATM has both nuclear and cytoplasmic functions, this review will focus on its roles in telomere metabolism and how ATM and telomeres serve as controllers of cellular responses to DNA damage.
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Affiliation(s)
- Tej K Pandita
- Center for Radiological Research, College of Physicians and Surgeons, Columbia University, New York, New York, NY 10032, USA.
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27
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Classen S, Ruggles JA, Schultz SC. Crystal structure of the N-terminal domain of Oxytricha nova telomere end-binding protein alpha subunit both uncomplexed and complexed with telomeric ssDNA. J Mol Biol 2001; 314:1113-25. [PMID: 11743727 DOI: 10.1006/jmbi.2000.5191] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Oxytricha nova telomere end-binding protein specifically recognizes and caps single strand (T(4)G(4))(n) telomeric DNA at the very 3'-ends of O. nova macronuclear chromosomes. Proteins homologous to the N-terminal domain of OnTEBP alpha subunit have now been identified in Oxytricha trifallax, Stylonychia mytilis, Euplotes crassus, Schizosaccharomyces pombe, and Homo sapiens, suggesting that this protein is widely distributed in eukaryotes. We describe here the crystal structures of the N-terminal single-stranded DNA (ssDNA)-binding domain of O. nova telomere end-binding protein alpha subunit both uncomplexed and complexed with single strand telomeric DNA. These structures show how the N-terminal domain of alpha alone, in the absence of the beta subunit and without alpha dimerization, can bind single-stranded telomeric DNA in a sequence-specific and 3'-end-specific manner. Furthermore, comparison of the uncomplexed and complexed forms of this protein shows that the ssDNA-binding site is largely pre-organized in the absence of ssDNA with modest, but interesting, rearrangements of amino acid side-chains that compose the ssDNA-binding site. The structures described here extend our understanding of structures of O. nova telomeric complexes by adding uncomplexed and complexed forms of monomeric alpha to previously described structures for (alpha 56/ssDNA)(2) dimer and alpha 56/beta 28/ssDNA ternary complexes. We believe that each of these four structures represent intermediates in an ordered assembly/disassembly pathway for O. nova telomeric complexes.
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Affiliation(s)
- S Classen
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO 80309-0215, USA.
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28
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Abstract
We envision multiple steps in telomere maintenance, based largely on genetic data from budding yeast. First, the telomere must unfold or open itself such that the free end is accessible to the appropriate enzymatic machinery. Second, telomerase must be recruited, together with the DNA replication machinery that synthesizes the C-rich strand. The processivity of telomerase is regulated both by a length-sensing feedback mechanism and by second-strand synthesis. Finally, the telosome refolds into a protective end structure. If telomerase is nonfunctional, recombination may occur once telomeres are open. Multiple pathways regulate these different steps, producing a highly dynamic chromosomal cap.
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Affiliation(s)
- K Dubrana
- Swiss Institute for Experimental Cancer Research (ISREC), Chemin des Boveresses 155, CH-1066 Epalinges/Lausanne, Switzerland
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29
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Pérez-Morga D, Amiguet-Vercher A, Vermijlen D, Pays E. Organization of telomeres during the cell and life cycles of Trypanosoma brucei. J Eukaryot Microbiol 2001; 48:221-6. [PMID: 12095111 DOI: 10.1111/j.1550-7408.2001.tb00306.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The genome of Trypanosoma brucei contains about 120 chromosomes, which do not visibly condense during mitosis. We have analyzed the organization and segregation of these chromosomes by in situ hybridization using fluorescent telomere probes. At the onset of mitosis, telomeres migrate from their nuclear peripheral location and congregate into a central zone. This dense group of telomeres then splits into two entities that migrate to opposite nuclear poles. Segregation continues until the double-sized nucleus divides and, before cytokinesis occurs, the telomeres reorganize into the discrete foci observed at interphase. During migration, the telomeres are located at the free end of the mitotic spindle. Treatment with the microtubule polymerization inhibitor rhizoxin prevents telomere clustering and chromosomal segregation. In the insect-specific procyclic form as well as in the non-dividing bloodstream stumpy form, telomeres tend to cluster close to the nuclear periphery at interphase. In contrast, in the proliferative bloodstream slender form the telomeres preferentially locate in the central zone of the nucleus. Thus, telomeres are closer to the nuclear periphery during those life cycle stages where the telomeric expression sites for the variant surface glycoprotein are all inactive, suggesting that transcriptional inactivation of these sites is related to their subnuclear localization.
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Affiliation(s)
- D Pérez-Morga
- Molecular Parasitology Laboratory, Université Libre de Bruxelles-Institut de Biologie et Médecine Moléculaires, Gosselies, Belgium.
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30
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Scherthan H, Jerratsch M, Li B, Smith S, Hultén M, Lock T, de Lange T. Mammalian meiotic telomeres: protein composition and redistribution in relation to nuclear pores. Mol Biol Cell 2000; 11:4189-203. [PMID: 11102517 PMCID: PMC15066 DOI: 10.1091/mbc.11.12.4189] [Citation(s) in RCA: 117] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Mammalian telomeres consist of TTAGGG repeats, telomeric repeat binding factor (TRF), and other proteins, resulting in a protective structure at chromosome ends. Although structure and function of the somatic telomeric complex has been elucidated in some detail, the protein composition of mammalian meiotic telomeres is undetermined. Here we show, by indirect immunofluorescence (IF), that the meiotic telomere complex is similar to its somatic counterpart and contains significant amounts of TRF1, TRF2, and hRap1, while tankyrase, a poly-(ADP-ribose)polymerase at somatic telomeres and nuclear pores, forms small signals at ends of human meiotic chromosome cores. Analysis of rodent spermatocytes reveals Trf1 at mouse, TRF2 at rat, and mammalian Rap1 at meiotic telomeres of both rodents. Moreover, we demonstrate that telomere repositioning during meiotic prophase occurs in sectors of the nuclear envelope that are distinct from nuclear pore-dense areas. The latter form during preleptotene/leptotene and are present during entire prophase I.
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Affiliation(s)
- H Scherthan
- University of Kaiserslautern, D-67653 Kaiserslautern, Germany.
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31
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Trelles-Sticken E, Dresser ME, Scherthan H. Meiotic telomere protein Ndj1p is required for meiosis-specific telomere distribution, bouquet formation and efficient homologue pairing. J Cell Biol 2000; 151:95-106. [PMID: 11018056 PMCID: PMC2189801 DOI: 10.1083/jcb.151.1.95] [Citation(s) in RCA: 170] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2000] [Accepted: 08/23/2000] [Indexed: 11/22/2022] Open
Abstract
We have investigated the requirements for NDJ1 in meiotic telomere redistribution and clustering in synchronized cultures of Saccharomyces cerevisiae. On induction of wild-type meiosis, telomeres disperse from premeiotic aggregates over the nuclear periphery, and then cluster near the spindle pole body (bouquet arrangement) before dispersing again. In ndj1Delta meiocytes, telomeres are scattered throughout the nucleus and fail to form perinuclear meiosis-specific distribution patterns, suggesting that Ndj1p may function to tether meiotic telomeres to the nuclear periphery. Since ndj1Delta meiocytes fail to cluster their telomeres at any prophase stage, Ndj1p is the first protein shown to be required for bouquet formation in a synaptic organism. Analysis of homologue pairing by two-color fluorescence in situ hybridization with cosmid probes to regions on III, IX, and XI revealed that disruption of bouquet formation is associated with a significant delay (>2 h) of homologue pairing. An increased and persistent fraction of ndj1Delta meiocytes with Zip1p polycomplexes suggests that chromosome polarization is important for synapsis progression. Thus, our observations support the hypothesis that meiotic telomere clustering contributes to efficient homologue alignment and synaptic pairing. Under naturally occurring conditions, bouquet formation may allow for rapid sporulation and confer a selective advantage.
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Affiliation(s)
- E Trelles-Sticken
- Department of Human Biology and Genetics, University of Kaiserslautern, D-67653 Kaiserslautern, Germany
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32
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Fujiwara H, Nakazato Y, Okazaki S, Ninaki O. Stability and Telomere Structure of Chromosomal Fragments in Two Different Mosaic Strains of the Silkworm, Bombyx mori. Zoolog Sci 2000. [DOI: 10.2108/zsj.17.743] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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33
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Slijepcevic P, Xiao Y, Natarajan AT. Chromosome-specific telomeric associations in Chinese hamster embryonic cells. Genes Chromosomes Cancer 2000; 28:98-105. [PMID: 10738308 DOI: 10.1002/(sici)1098-2264(200005)28:1<98::aid-gcc12>3.0.co;2-u] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Telomeric associations (TAs) represent an important cytogenetic marker of human tumor cells. It has been thought that the primary cause of TAs is telomere shortening. However, we report here a surprising aspect of telomere maintenance in primary Chinese hamster embryonic (CHE) cells: relatively high frequencies of TAs in spite of normal telomere length. These TAs are present in both interphase and metaphase cells, suggesting that metaphase TAs may be relics of interphase chromosome organization. In addition, some TAs observed here are chromosome-specific and recurrent in at least three consecutive cell cycles in two different CHE cell strains. In spite of relatively high frequencies of TAs, none of the CHE strains show chromosome instability resulting from breakage-fusion-bridge cycles, as would be expected from tumor cell studies. It appears that TAs in CHE cells may be reversible events. These results are discussed in light of current understanding of telomere biology.
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Affiliation(s)
- P Slijepcevic
- Department of Biological Sciences, Brunel University, Uxbridge, Middlesex, England.
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34
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Smogorzewska A, van Steensel B, Bianchi A, Oelmann S, Schaefer MR, Schnapp G, de Lange T. Control of human telomere length by TRF1 and TRF2. Mol Cell Biol 2000; 20:1659-68. [PMID: 10669743 PMCID: PMC85349 DOI: 10.1128/mcb.20.5.1659-1668.2000] [Citation(s) in RCA: 549] [Impact Index Per Article: 22.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Telomere length in human cells is controlled by a homeostasis mechanism that involves telomerase and the negative regulator of telomere length, TRF1 (TTAGGG repeat binding factor 1). Here we report that TRF2, a TRF1-related protein previously implicated in protection of chromosome ends, is a second negative regulator of telomere length. Overexpression of TRF2 results in the progressive shortening of telomere length, similar to the phenotype observed with TRF1. However, while induction of TRF1 could be maintained over more than 300 population doublings and resulted in stable, short telomeres, the expression of exogenous TRF2 was extinguished and the telomeres eventually regained their original length. Consistent with their role in measuring telomere length, indirect immunofluorescence indicated that both TRF1 and TRF2 bind to duplex telomeric DNA in vivo and are more abundant on telomeres with long TTAGGG repeat tracts. Neither TRF1 nor TRF2 affected the expression level of telomerase. Furthermore, the presence of TRF1 or TRF2 on a short linear telomerase substrate did not inhibit the enzymatic activity of telomerase in vitro. These findings are consistent with the recently proposed t loop model of telomere length homeostasis in which telomerase-dependent telomere elongation is blocked by sequestration of the 3' telomere terminus in TRF1- and TRF2-induced telomeric loops.
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Affiliation(s)
- A Smogorzewska
- The Rockefeller University, New York, New York 10021, USA
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35
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Kozik A, Bradbury EM, Zalensky AO. Identification and characterization of a bovine sperm protein that binds specifically to single-stranded telomeric deoxyribonucleic acid. Biol Reprod 2000; 62:340-6. [PMID: 10642571 DOI: 10.1095/biolreprod62.2.340] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
Telomere DNA at the physical termini of chromosomes forms a single-stranded 3' overhang. In lower eukaryotes, e.g., ciliated protozoa, this DNA extension is capped by specific proteins that have been structurally and functionally characterized. Much less is known about single-stranded telomere DNA-binding proteins in vertebrates. Here we describe a new protein from bovine sperm designated bsSSTBP that specifically interacts with single-stranded (TTAGGG)(N) DNA. The bsSSTBP was extracted from nuclei by 0.6 M KCl. The native size of this protein, estimated by gel filtration, was 20-40 kDa. SDS-PAGE of the UV cross-linked complex between bsSSTBP and telomere DNA indicated that several polypeptides are involved in complex formation. Bovine sSSTB had high specificity toward nucleotide sequence, since single nucleotide substitutions in the (TTAGGG)(4) substrate suppressed binding. The minimal number of (TTAGGG) repeats required for binding of bsSSTBP was 3, and the protein recognized linear but not folded DNA structures. We propose that the bsSSTBP participates in telomere-telomere interactions and the telomere membrane localization observed in mature sperm. In mammals, somatic telomere-binding proteins are apparently substituted by sperm-specific ones that may lead to a structural reorganization of telomere domains to fulfill functions important during meiosis and fertilization.
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Affiliation(s)
- A Kozik
- Department of Biological Chemistry, School of Medicine, University of California at Davis, Davis, California 95616, USA
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36
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Pierron G, Puvion-Dutilleul F. An anchorage nuclear structure for telomeric DNA repeats in HeLa cells. Chromosome Res 2000; 7:581-92. [PMID: 10628659 DOI: 10.1023/a:1009253917125] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Using either a biotinylated peptide nucleic acid (PNA) oligomer or a digoxigenin-labeled double-stranded DNA probe, we determined the distribution of the telomeric DNA repeats in HeLa cells by in-situ hybridization at the ultrastructural level. The telomeric DNA was found at the periphery of previously unrecognized roundish nuclear structures, distributed throughout the nucleoplasm. The levels of association of the telomeric DNA with these structures was investigated by exposure of cells to a detergent-containing hypotonic solution which only preserves tightly linked components. The telomeric DNA repeats stayed associated with their anchorage structures following spreading apart of nucleoproteins. Because changes in cellular DNA topology are associated with the intranuclear development of herpes simplex virus type 1 (HSV-1) and adenovirus type 5 (Ad5) in HeLa cells, we examined the distribution of telomeric DNA when cellular DNA is pushed toward the nuclear border. The circular telomeric complexes were morphologically unmodified; however, as a result of the partition of cellular and viral DNA in two concentric compartments, they migrated towards the nuclear border, along with the compressed cellular chromatin. Taken together, our results exemplify the unique organization of the telomeric DNA, which is coiled around a central core of a diameter of 120 nm and can therefore be clearly distinguished from the bulk of the cellular chromatin.
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Affiliation(s)
- G Pierron
- Laboratoire Organisation fonctionnelle du Noyau, UPR 1983 CNRS, Institut de Recherches sur le Cancer/IFC1, Villejuif, France
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37
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Molecular Cell Biology: Role of Repetitive DNA in Nuclear Architecture and Chromosome Structure. ACTA ACUST UNITED AC 2000. [DOI: 10.1007/978-3-642-57203-6_5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/17/2023]
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38
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Liu WS, Fredga K. Telomeric (TTAGGG)n sequences are associated with nucleolus organizer regions (NORs) in the wood lemming. Chromosome Res 1999; 7:235-40. [PMID: 10421383 DOI: 10.1023/a:1009255517764] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The distribution of the (TTAGGG)n telomeric sequence was studied in chromosomes of the wood lemming, Myopus schisticolor, by fluorescence in-situ hybridization. As expected, the hybridization signals were observed at telomeres of all chromosomes. However, quite a number of interstitial telomeric sites were present in the pericentric heterochromatic regions. Consistent strong hybridization signals were also seen at one terminus of chromosomes 5, 7 and 12--15. By post-hybridization G-banding and silver-staining, the large blocks of the telomeric sequences on chromosomes 5 and 12 were localized to nucleolus organizer regions (NORs).
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Affiliation(s)
- W S Liu
- Department of Conservation Biology and Genetics, Uppsala University, Uppsala Genetic Centre, Sweden.
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39
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Abstract
In yeast, the constant length of telomeric DNA results from a negative regulation of telomerase by the telomere itself. Here we follow the return to equilibrium of an abnormally shortened telomere. We observe that telomere elongation is restricted to a few base pairs per generation and that its rate decreases progressively with increasing telomere length. In contrast, in the absence of telomerase or in the presence of an over-elongated telomere, the degradation rate linked to the succession of generations appears to be constant, i.e. independent of telomere length. Together, these results indicate that telomerase is gradually inhibited at its site of action by the elongating telomere. The implications of this finding for the dynamics of telomere length regulation are discussed in this study.
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Affiliation(s)
- S Marcand
- Laboratoire de Biologie Moléculaire et Cellulaire, Ecole Normale Supérieure de Lyon, UMR8510 CNRS/ENSL, 69364 Lyon Cedex 07, France
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40
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Abstract
The leptotene/zygotene transition of meiosis, as defined by classical cytological studies, is the period when homologous chromosomes, already being discernible individualized entities, begin to be close together or touching over portions of their lengths. This period also includes the bouquet stage: Chromosome ends, which have already become integral components of the inner nuclear membrane, move into a polarized configuration, along with other nuclear envelope components. Chromosome movements, active or passive, also occur. The detailed nature of interhomologue interactions during this period, with special emphasis on the involvement of chromosome ends, and the overall role for meiosis and recombination of chromosome movement and, especially, the bouquet stage are discussed.
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Affiliation(s)
- D Zickler
- Institut de Génétique et Microbiologie, Université Paris-Sud, Orsay, France.
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41
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Abstract
An increase in the length of telomeres in human sperm compared to somatic cells has long been noted and considered within a popular hypothesis involving telomere shortening and cell aging. In the present study we determined telomere length in two species with long terminal TTAGGG arrays--bovine and porcine. Using several independent methods we demonstrate that the telomeres in the sperm of human, porcine and bovine are elongated by 69%, 24%, and 14%, respectively, in comparison with somatic tissues. Therefore, increased sperm telomere length is a feature preserved throughout mammalian evolution. The biological role of this phenomenon is discussed in the context of telomere functions in meiosis and fertilization.
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Affiliation(s)
- A Kozik
- Department of Biological Chemistry, School of Medicine, University of California, Davis 95616, USA
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42
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Abstract
Certain haploid strains of Saccharomyces cerevisiae can undergo meiosis, but meiotic prophase progression and subsequent nuclear division are delayed if these haploids carry an extra chromosome (i. e., are disomic). Observations indicate that interactions between homologous chromosomes cause a delay in meiotic prophase, perhaps to allow time for interhomolog interactions to be completed. Analysis of meiotic mutants demonstrates that the relevant aspect of homolog recognition is independent of meiotic recombination and synaptonemal complex formation. A disome in which the extra chromosome is circular sporulates without a delay, indicating that telomeres are important for homolog recognition. Consistent with this hypothesis, fluorescent in situ hybridization demonstrates that a circular chromosome has a reduced capacity to pair with its homolog, and a telomere-associated meiotic protein (Ndj1) is required to delay sporulation in disomes. A circular dimer containing two copies of the same chromosome delays meiosis to the same extent as two linear homologs, implying that physical proximity bypasses the requirement for telomeres in homolog pairing. Analysis of a disome carrying two linear permuted chromosomes suggests that even nonhomologous chromosome ends can promote homolog pairing to a limited extent. We speculate that telomere-mediated chromosome movement and/or telomere clustering promote homolog pairing.
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Affiliation(s)
- B Rockmill
- Howard Hughes Medical Institute, Yale University, New Haven, Connecticut 06520-8103 USA
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43
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Jin Q, Trelles-Sticken E, Scherthan H, Loidl J. Yeast nuclei display prominent centromere clustering that is reduced in nondividing cells and in meiotic prophase. J Cell Biol 1998; 141:21-9. [PMID: 9531545 PMCID: PMC2132713 DOI: 10.1083/jcb.141.1.21] [Citation(s) in RCA: 152] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/1997] [Revised: 02/04/1998] [Indexed: 02/07/2023] Open
Abstract
Chromosome arrangement in spread nuclei of the budding yeast, Saccharomyces cerevisiae was studied by fluorescence in situ hybridization with probes to centromeres and telomeric chromosome regions. We found that during interphase centromeres are tightly clustered in a peripheral region of the nucleus, whereas telomeres tend to occupy the area outside the centromeric domain. In vigorously growing cultures, centromere clustering occurred in approximately 90% of cells and it appeared to be maintained throughout interphase. It was reduced when cells were kept under stationary conditions for an extended period. In meiosis, centromere clusters disintegrated before the emergence of the earliest precursors of the synaptonemal complex. Evidence for the contribution of centromere clustering to other aspects of suprachromosomal nuclear order, in particular the vegetative association of homologous chromosomes, is provided, and a possible supporting role in meiotic homology searching is discussed.
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Affiliation(s)
- Q Jin
- Institute of Botany, University of Vienna, A-1030 Vienna, Austria
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44
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Ikonomova R, Sommer T, Képès F. The Srp40 protein plays a dose-sensitive role in preribosome assembly or transport and depends on its carboxy-terminal domain for proper localization to the yeast nucleoskeleton. DNA Cell Biol 1997; 16:1161-73. [PMID: 9364927 DOI: 10.1089/dna.1997.16.1161] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The yeast SRP40 gene product (Srp40p) is a highly serine-rich protein organized in three distinct domains. The roles of these domains in localizing Srp40p were determined. By indirect immunofluorescence microscopy, Srp40p localizes to punctate, sometimes fibrillar, subnuclear structures that might include the nucleolus. Its amino-terminal and medial domains are similar. They each start with a short basic stretch containing a nuclear localization signal, followed by a long acidic stretch with 76% serines; such acidic stretches are thought to mediate binding to ribosomal proteins in the nucleolus. Either domain is sufficient to determine nuclear localization of Srp40p. The Srp40p carboxy-terminal domain shows significant homology to the cognate domain of Nopp140, a mammalian nucleolar phosphoprotein of 140 kD. The carboxy-terminal domain alone, or fused to a reporter protein, displays a punctate localization outside the nucleus. Srp40p and Nopp140 share a highly homologous 39-residue motif within their similar carboxy-terminal domains. Inside or outside the nucleus, this motif is important to prevent Srp40p diffusion or degradation. These observations suggest that the punctate immunoreactive structure is nucleoskeletal and might result from Srp40p self-assembly. SRP40 genetically interacts with four mutants affected in stable RNA synthesis and one mutant blocked in protein translocation to the endoplasmic reticulum. Growth defects, but no translocation or rRNA transcription/maturation phenotypes, were observed upon SRP40 inactivation or strong overexpression. Together, these data point to a dispensable, dosage-sensitive, role of Srp40p in preribosome assembly or transport.
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Affiliation(s)
- R Ikonomova
- Service de Biochimie et de Génétique Moléculaire, DBCM/DSV, CEA/Saclay, Gif, France
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45
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Blue C, Marcand S, Gilson E. Proteins that bind to double-stranded regions of telomeric DNA. Trends Cell Biol 1997; 7:317-24. [PMID: 17708967 DOI: 10.1016/s0962-8924(97)01092-1] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
In budding yeast, the DNA-binding protein Rap1p orchestrates a negative feedback on regulation of telomere length and the organization of a heterochromatin-like telomeric compartment. Recent studies have led to the identification of functionally related telomeric proteins from fission yeast and mammals. These advances underline the key role played by the proteins that bind to the duplex part of telomeric DNA and reveal an important structural diversity among telomeric proteins.
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46
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Higashiyama T, Noutoshi Y, Fujie M, Yamada T. Zepp, a LINE-like retrotransposon accumulated in the Chlorella telomeric region. EMBO J 1997; 16:3715-23. [PMID: 9218812 PMCID: PMC1169995 DOI: 10.1093/emboj/16.12.3715] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Six copies of insertion elements accumulate in the subtelomeric region immediately proximal to the telomeric repeats on Chlorella chromosome I. The elements, designated Zepps, bear the characteristic features of non-viral (LINE-like) retrotransposons, including a poly(A) tail, 5'-truncations, a retroviral reverse transcriptase-like ORF and flanking target duplications. Detailed sequence analysis of the Chlorella subtelomeric region revealed a novel mechanism of Zepp transposition; successive insertions of each Zepp element into another Zepp as a target, leaving a tandem array of their 3'-regions with poly(A) tracts facing toward the centromere. Only the most distal Zepp copy was inverted to connect its poly(A) tail with the telomeric repeats. A similar Zepp cluster but without the telomeric repeats was also found at the terminus of another Chlorella chromosome. These structures contrast with that proposed for the addition of HeT-A and TART elements to Drosophila telomeres. Expression of Zepp elements is induced by heat shock treatment. Possible roles of the subtelomeric retrotransposons in formation and maintenance of telomeres are discussed.
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Affiliation(s)
- T Higashiyama
- Faculty of Engineering, Hiroshima University, Higashi-Hiroshima, Japan
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47
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Zalensky AO, Tomilin NV, Zalenskaya IA, Teplitz RL, Bradbury EM. Telomere-telomere interactions and candidate telomere binding protein(s) in mammalian sperm cells. Exp Cell Res 1997; 232:29-41. [PMID: 9141618 DOI: 10.1006/excr.1997.3482] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
We have used fluorescent in situ hybridization to localize telomeres within the nuclei of sperm from six mammals (human, rat, mouse, stallion, boar, and bull). In minimally swollen sperm of mouse and rat, most of the telomeres are clustered within a limited area in the posterior part of nuclei. In sperm of other species, telomeres associate into tetrameres and dimers. On swelling of sperm cells with heparin/dithiotriethol, telomere associations disperse, and hybridization signals become smaller in size and their numbers approach or correspond to the number of chromosome ends in a haploid genome. Quantitation of telomere loci indicates that dimeric associations are prominent features of mammalian sperm nuclear architecture. Higher order telomere-telomere interactions and organization develop during meiotic stages of human spermatogenesis. At this stage, telomeres also become associated with the nuclear membrane. In an attempt to elucidate the molecular mechanisms underlying telomere interactions in sperm, we have identified a novel protein activity that binds to the double-stranded telomeric repeat (TTAGGG)n. Sperm telomere binding protein(s) (STBP) was extracted from human and bull sperm by 0.5 M NaCl. STBP does not bind single-stranded telomeric DNA and is highly specific for single base substitutions in a duplex DNA sequence. Depending on the conditions of binding, we observed the formation of several nucleoprotein complexes. We have shown that there is a transition between complexes, which indicates that the slower migrating complex is a multimer of the higher mobility one. We propose that STBP participates in association between the telomere domains which were microscopically observed in mammalian spermatozoa.
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Affiliation(s)
- A O Zalensky
- Department of Biological Chemistry, School of Medicine, University of California at Davis, 95616, USA.
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48
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Abstract
The sequence organisation of the telomeric regions is extremely similar for all eukaryotes examined to date. Subtelomeric areas may contain large sequence arrays of middle repetitive, complex elements that sometimes have similarities to retrotransposons. In between and within these complex sequences are short, satellite-like repeats. These areas contain very few genes and are thought to be organised into a heterochromatin-like domain. The terminal regions almost invariably consist of short, direct repeats. These repeats usually contain clusters of 2-4 G residues and the strand that contains these clusters (the G strand) always forms the extreme 3'-end of the chromosome. Thus, most telomeric repeats are clearly related to each other which in turn suggests a common evolutionary origin. A number of different structures can be formed by single-stranded telomeric G strand repeats and, as has been suggested recently, by the G strand. Since the main mechanism for the maintenance of telomeric repeats predicts the occurrence of single-stranded extensions of the G strand, the propensity of G-rich DNA to fold into alternative DNA structures may have implications for telomere biology.
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Affiliation(s)
- R J Wellinger
- Faculté de Médecine, Department de Microbiologie et Infectiologie, Université de Sherbrooke, QC, Canada
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49
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Cenci G, Rawson RB, Belloni G, Castrillon DH, Tudor M, Petrucci R, Goldberg ML, Wasserman SA, Gatti M. UbcD1, a Drosophila ubiquitin-conjugating enzyme required for proper telomere behavior. Genes Dev 1997; 11:863-75. [PMID: 9106658 DOI: 10.1101/gad.11.7.863] [Citation(s) in RCA: 99] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The end-to-end association of chromosomes through their telomeres has been observed in normal cells of certain organisms, as well as in senescent and tumor cells. The molecular mechanisms underlying this phenomenon are currently unknown. We show here that five independent mutant alleles in the Drosophila UbcD1 gene cause frequent telomere-telomere attachments during both mitosis and male meiosis that are not seen in wild type. These telomeric associations involve all the telomeres of the D. melanogaster chromosome complement, albeit with different frequencies. The pattern of telomeric associations observed in UbcD1 mutants suggests strongly that the interphase chromosomes of wild-type larval brain cells maintain a Rab1 orientation within the nucleus, with the telomeres and centromeres segregated to opposite sides of the nucleus. The UbcD1 gene encodes a class I ubiquitin-conjugating (E2) enzyme. This indicates that ubiquitin-mediated proteolysis is normally needed to ensure proper telomere behavior during Drosophila cell division. We therefore suggest that at least one of the targets of UbcD1 ubiquitination is a telomere-associated polypeptide that may help maintain proper chromosomal orientation during interphase.
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Affiliation(s)
- G Cenci
- Dipartimento di Genetica e Biologia Molecolare, Universitá di Roma La Sapienza, Rome, Italy
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50
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Grandin N, Reed SI, Charbonneau M. Stn1, a new Saccharomyces cerevisiae protein, is implicated in telomere size regulation in association with Cdc13. Genes Dev 1997; 11:512-27. [PMID: 9042864 DOI: 10.1101/gad.11.4.512] [Citation(s) in RCA: 231] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
We have isolated STN1, an essential Saccharomyces cerevisiae gene, as a suppressor of the cdc13-1 mutation. A synthetic lethal interaction between a temperature-sensitive mutant allele of STN1, stn1-13, and cdc13-1 was observed. Stn1 and Cdc13 proteins displayed a physical interaction by two-hybrid analysis. As shown previously for cdc13-1, stn1-13 cells at the restrictive temperature accumulate single-stranded DNA in subtelomeric regions of the chromosomes, but to a lesser extent than cdc13-1 cells. In addition, both Cdc13 and Stn1 were found to be involved in the regulation of telomere length, mutations in STN1 or CDC13 conferring an increase in telomere size. Loss of Stn1 function activated the RAD9 and MEC3 G2/M checkpoints, therefore confirming that DNA damage is generated. We propose that Stn1 functions in telomere metabolism during late S phase in cooperation with Cdc13.
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Affiliation(s)
- N Grandin
- Yeast Cell Cycle Group, Unité Mixte de Recherche Centre National de laRecherche Scientifique/Ecole Normale Supérieure (UMR CNRS/ENS), no. 49, Lyon, France
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