1
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Sosa Ponce ML, Cobb JA, Zaremberg V. Lipids and chromatin: a tale of intriguing connections shaping genomic landscapes. Trends Cell Biol 2024:S0962-8924(24)00118-1. [PMID: 39060139 DOI: 10.1016/j.tcb.2024.06.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2024] [Revised: 06/03/2024] [Accepted: 06/11/2024] [Indexed: 07/28/2024]
Abstract
Recent studies in yeast reveal an intricate interplay between nuclear envelope (NE) architecture and lipid metabolism, and between lipid signaling and both epigenome and genome integrity. In this review, we highlight the reciprocal connection between lipids and histone modifications, which enable metabolic reprogramming in response to nutrients. The endoplasmic reticulum (ER)-NE regulates the compartmentalization and temporal availability of epigenetic metabolites and its lipid composition also impacts nuclear processes, such as transcriptional silencing and the DNA damage response (DDR). We also discuss recent work providing mechanistic insight into lipid droplet (LD) formation and sterols in the nucleus, and the collective data showing Opi1 as a central factor in both membrane sensing and transcriptional regulation of lipid-chromatin interrelated processes.
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Affiliation(s)
- Maria Laura Sosa Ponce
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, Canada
| | - Jennifer A Cobb
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, Canada
| | - Vanina Zaremberg
- Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada.
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2
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Sosa Ponce ML, Remedios MH, Moradi-Fard S, Cobb JA, Zaremberg V. SIR telomere silencing depends on nuclear envelope lipids and modulates sensitivity to a lysolipid. J Cell Biol 2023; 222:e202206061. [PMID: 37042812 PMCID: PMC10103788 DOI: 10.1083/jcb.202206061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Revised: 11/29/2022] [Accepted: 03/24/2023] [Indexed: 04/13/2023] Open
Abstract
The nuclear envelope (NE) is important in maintaining genome organization. The role of lipids in communication between the NE and telomere regulation was investigated, including how changes in lipid composition impact gene expression and overall nuclear architecture. Yeast was treated with the non-metabolizable lysophosphatidylcholine analog edelfosine, known to accumulate at the perinuclear ER. Edelfosine induced NE deformation and disrupted telomere clustering but not anchoring. Additionally, the association of Sir4 at telomeres decreased. RNA-seq analysis showed altered expression of Sir-dependent genes located at sub-telomeric (0-10 kb) regions, consistent with Sir4 dispersion. Transcriptomic analysis revealed that two lipid metabolic circuits were activated in response to edelfosine, one mediated by the membrane sensing transcription factors, Spt23/Mga2, and the other by a transcriptional repressor, Opi1. Activation of these transcriptional programs resulted in higher levels of unsaturated fatty acids and the formation of nuclear lipid droplets. Interestingly, cells lacking Sir proteins displayed resistance to unsaturated-fatty acids and edelfosine, and this phenotype was connected to Rap1.
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Affiliation(s)
| | | | - Sarah Moradi-Fard
- Departments of Biochemistry and Molecular Biology and Oncology, Cumming School of Medicine, Robson DNA Science Centre, Arnie Charbonneau Cancer Institute, Calgary, Canada
| | - Jennifer A. Cobb
- Departments of Biochemistry and Molecular Biology and Oncology, Cumming School of Medicine, Robson DNA Science Centre, Arnie Charbonneau Cancer Institute, Calgary, Canada
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, Canada
| | - Vanina Zaremberg
- Department of Biological Sciences, University of Calgary, Calgary, Canada
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3
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García Fernández F, Almayrac E, Carré Simon À, Batrin R, Khalil Y, Boissac M, Fabre E. Global chromatin mobility induced by a DSB is dictated by chromosomal conformation and defines the HR outcome. eLife 2022; 11:78015. [PMID: 36125964 PMCID: PMC9489209 DOI: 10.7554/elife.78015] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2022] [Accepted: 09/08/2022] [Indexed: 12/16/2022] Open
Abstract
Repair of DNA double-strand breaks (DSBs) is crucial for genome integrity. A conserved response to DSBs is an increase in chromatin mobility that can be local, at the site of the DSB, or global, at undamaged regions of the genome. Here, we address the function of global chromatin mobility during homologous recombination (HR) of a single, targeted, controlled DSB. We set up a system that tracks HR in vivo over time and show that two types of DSB-induced global chromatin mobility are involved in HR, depending on the position of the DSB. Close to the centromere, a DSB induces global mobility that depends solely on H2A(X) phosphorylation and accelerates repair kinetics, but is not essential. In contrast, the global mobility induced by a DSB away from the centromere becomes essential for HR repair and is triggered by homology search through a mechanism that depends on H2A(X) phosphorylation, checkpoint progression, and Rad51. Our data demonstrate that global mobility is governed by chromosomal conformation and differentially coordinates repair by HR.
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Affiliation(s)
| | - Etienne Almayrac
- Université de Paris, IRSL, INSERM, U944, CNRS, UMR7212, Paris, France
| | - Ànnia Carré Simon
- Université de Paris, IRSL, INSERM, U944, CNRS, UMR7212, Paris, France
| | - Renaud Batrin
- Université de Paris, IRSL, INSERM, U944, CNRS, UMR7212, Paris, France
| | - Yasmine Khalil
- Université de Paris, IRSL, INSERM, U944, CNRS, UMR7212, Paris, France
| | - Michel Boissac
- Université de Paris, IRSL, INSERM, U944, CNRS, UMR7212, Paris, France
| | - Emmanuelle Fabre
- Université de Paris, IRSL, INSERM, U944, CNRS, UMR7212, Paris, France
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4
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Telomeres and Their Neighbors. Genes (Basel) 2022; 13:genes13091663. [PMID: 36140830 PMCID: PMC9498494 DOI: 10.3390/genes13091663] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Revised: 09/08/2022] [Accepted: 09/09/2022] [Indexed: 11/21/2022] Open
Abstract
Telomeres are essential structures formed from satellite DNA repeats at the ends of chromosomes in most eukaryotes. Satellite DNA repeat sequences are useful markers for karyotyping, but have a more enigmatic role in the eukaryotic cell. Much work has been done to investigate the structure and arrangement of repetitive DNA elements in classical models with implications for species evolution. Still more is needed until there is a complete picture of the biological function of DNA satellite sequences, particularly when considering non-model organisms. Celebrating Gregor Mendel’s anniversary by going to the roots, this review is designed to inspire and aid new research into telomeres and satellites with a particular focus on non-model organisms and accessible experimental and in silico methods that do not require specialized equipment or expensive materials. We describe how to identify telomere (and satellite) repeats giving many examples of published (and some unpublished) data from these techniques to illustrate the principles behind the experiments. We also present advice on how to perform and analyse such experiments, including details of common pitfalls. Our examples are a selection of recent developments and underexplored areas of research from the past. As a nod to Mendel’s early work, we use many examples from plants and insects, especially as much recent work has expanded beyond the human and yeast models traditional in telomere research. We give a general introduction to the accepted knowledge of telomere and satellite systems and include references to specialized reviews for the interested reader.
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5
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García Fernández F, Fabre E. The Dynamic Behavior of Chromatin in Response to DNA Double-Strand Breaks. Genes (Basel) 2022; 13:genes13020215. [PMID: 35205260 PMCID: PMC8872016 DOI: 10.3390/genes13020215] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Revised: 01/18/2022] [Accepted: 01/19/2022] [Indexed: 02/05/2023] Open
Abstract
The primary functions of the eukaryotic nucleus as a site for the storage, retrieval, and replication of information require a highly dynamic chromatin organization, which can be affected by the presence of DNA damage. In response to double-strand breaks (DSBs), the mobility of chromatin at the break site is severely affected and, to a lesser extent, that of other chromosomes. The how and why of such movement has been widely studied over the last two decades, leading to different mechanistic models and proposed potential roles underlying both local and global mobility. Here, we review the state of the knowledge on current issues affecting chromatin mobility upon DSBs, and highlight its role as a crucial step in the DNA damage response (DDR).
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Affiliation(s)
- Fabiola García Fernández
- Institut Curie, CNRS UMR3664, Sorbonne Université, F-75005 Paris, France
- Correspondence: (F.G.F.); (E.F.)
| | - Emmanuelle Fabre
- Génomes Biologie Cellulaire et Thérapeutiques, CNRS UMR7212, INSERM U944, Université de Paris, F-75010 Paris, France
- Correspondence: (F.G.F.); (E.F.)
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6
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3D Genome Organization: Causes and Consequences for DNA Damage and Repair. Genes (Basel) 2021; 13:genes13010007. [PMID: 35052348 PMCID: PMC8775012 DOI: 10.3390/genes13010007] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Revised: 12/16/2021] [Accepted: 12/18/2021] [Indexed: 01/02/2023] Open
Abstract
The inability to repair damaged DNA severely compromises the integrity of any organism. In eukaryotes, the DNA damage response (DDR) operates within chromatin, a tightly organized DNA–histone complex in a non-random manner within the nucleus. Chromatin thus orchestrates various cellular processes, including repair. Here, we examine the chromatin landscape before, during, and after the DNA damage, focusing on double strand breaks (DSBs). We study how chromatin is modified during the repair process, not only around the damaged region (in cis), but also genome-wide (in trans). Recent evidence has highlighted a complex landscape in which different chromatin parameters (stiffness, compaction, loops) are transiently modified, defining “codes” for each specific stage of the DDR. We illustrate a novel aspect of DDR where chromatin modifications contribute to the movement of DSB-damaged chromatin, as well as undamaged chromatin, ensuring the mobilization of DSBs, their clustering, and their repair processes.
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7
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Ruault M, Scolari VF, Lazar-Stefanita L, Hocher A, Loïodice I, Koszul R, Taddei A. Sir3 mediates long-range chromosome interactions in budding yeast. Genome Res 2021; 31:411-425. [PMID: 33579753 PMCID: PMC7919453 DOI: 10.1101/gr.267872.120] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Accepted: 12/30/2020] [Indexed: 11/24/2022]
Abstract
Physical contacts between distant loci contribute to regulate genome function. However, the molecular mechanisms responsible for settling and maintaining such interactions remain poorly understood. Here, we investigate the well-conserved interactions between heterochromatin loci. In budding yeast, the 32 telomeres cluster in 3–5 foci in exponentially growing cells. This clustering is functionally linked to the formation of heterochromatin in subtelomeric regions through the recruitment of the silencing SIR complex composed of Sir2/3/4. Combining microscopy and Hi-C on strains expressing different alleles of SIR3, we show that the binding of Sir3 directly promotes long-range contacts between distant regions, including the rDNA, telomeres, and internal Sir3-bound sites. Furthermore, we unveil a new property of Sir3 in promoting rDNA compaction. Finally, using a synthetic approach, we demonstrate that Sir3 can bond loci belonging to different chromosomes together, when targeted to these loci, independently of its interaction with its known partners (Rap1, Sir4), Sir2 activity, or chromosome context. Altogether, these data suggest that Sir3 acts as a molecular bridge that stabilizes long-range interactions.
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Affiliation(s)
- Myriam Ruault
- Institut Curie, PSL University, Sorbonne Université, CNRS, Nuclear Dynamics, 75005 Paris, France
| | - Vittore F Scolari
- Institut Curie, PSL University, Sorbonne Université, CNRS, Nuclear Dynamics, 75005 Paris, France.,Institut Pasteur, Unité Régulation Spatiale des Génomes, CNRS, UMR 3525, C3BI USR 3756, F-75015 Paris, France
| | - Luciana Lazar-Stefanita
- Institut Pasteur, Unité Régulation Spatiale des Génomes, CNRS, UMR 3525, C3BI USR 3756, F-75015 Paris, France.,Sorbonne Université, collège Doctoral, F-75005 Paris, France
| | - Antoine Hocher
- Institut Curie, PSL University, Sorbonne Université, CNRS, Nuclear Dynamics, 75005 Paris, France
| | - Isabelle Loïodice
- Institut Curie, PSL University, Sorbonne Université, CNRS, Nuclear Dynamics, 75005 Paris, France
| | - Romain Koszul
- Institut Pasteur, Unité Régulation Spatiale des Génomes, CNRS, UMR 3525, C3BI USR 3756, F-75015 Paris, France.,Cogitamus Laboratory, F-75005 Paris, France
| | - Angela Taddei
- Institut Curie, PSL University, Sorbonne Université, CNRS, Nuclear Dynamics, 75005 Paris, France.,Cogitamus Laboratory, F-75005 Paris, France
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8
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Takemata N, Samson RY, Bell SD. Physical and Functional Compartmentalization of Archaeal Chromosomes. Cell 2020; 179:165-179.e18. [PMID: 31539494 DOI: 10.1016/j.cell.2019.08.036] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Revised: 06/20/2019] [Accepted: 08/21/2019] [Indexed: 01/18/2023]
Abstract
The three-dimensional organization of chromosomes can have a profound impact on their replication and expression. The chromosomes of higher eukaryotes possess discrete compartments that are characterized by differing transcriptional activities. Contrastingly, most bacterial chromosomes have simpler organization with local domains, the boundaries of which are influenced by gene expression. Numerous studies have revealed that the higher-order architectures of bacterial and eukaryotic chromosomes are dependent on the actions of structural maintenance of chromosomes (SMC) superfamily protein complexes, in particular, the near-universal condensin complex. Intriguingly, however, many archaea, including members of the genus Sulfolobus do not encode canonical condensin. We describe chromosome conformation capture experiments on Sulfolobus species. These reveal the presence of distinct domains along Sulfolobus chromosomes that undergo discrete and specific higher-order interactions, thus defining two compartment types. We observe causal linkages between compartment identity, gene expression, and binding of a hitherto uncharacterized SMC superfamily protein that we term "coalescin."
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Affiliation(s)
- Naomichi Takemata
- Molecular and Cellular Biochemistry Department, Indiana University, Bloomington, IN, USA; Biology Department, Indiana University, Bloomington, IN, USA
| | - Rachel Y Samson
- Molecular and Cellular Biochemistry Department, Indiana University, Bloomington, IN, USA
| | - Stephen D Bell
- Molecular and Cellular Biochemistry Department, Indiana University, Bloomington, IN, USA; Biology Department, Indiana University, Bloomington, IN, USA.
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9
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Genomic Considerations for the Modification of Saccharomyces cerevisiae for Biofuel and Metabolite Biosynthesis. Microorganisms 2020; 8:microorganisms8030321. [PMID: 32110897 PMCID: PMC7143498 DOI: 10.3390/microorganisms8030321] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Revised: 02/02/2020] [Accepted: 02/24/2020] [Indexed: 11/22/2022] Open
Abstract
The growing global population and developing world has put a strain on non-renewable natural resources, such as fuels. The shift to renewable sources will, thus, help meet demands, often through the modification of existing biosynthetic pathways or the introduction of novel pathways into non-native species. There are several useful biosynthetic pathways endogenous to organisms that are not conducive for the scale-up necessary for industrial use. The use of genetic and synthetic biological approaches to engineer these pathways in non-native organisms can help ameliorate these challenges. The budding yeast Saccharomyces cerevisiae offers several advantages for genetic engineering for this purpose due to its widespread use as a model system studied by many researchers. The focus of this review is to present a primer on understanding genomic considerations prior to genetic modification and manipulation of S. cerevisiae. The choice of a site for genetic manipulation can have broad implications on transcription throughout a region and this review will present the current understanding of position effects on transcription.
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10
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Adam N, Degelman E, Briggs S, Wazen RM, Colarusso P, Riabowol K, Beattie T. Telomere analysis using 3D fluorescence microscopy suggests mammalian telomere clustering in hTERT-immortalized Hs68 fibroblasts. Commun Biol 2019; 2:451. [PMID: 31815205 PMCID: PMC6893014 DOI: 10.1038/s42003-019-0692-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2019] [Accepted: 11/04/2019] [Indexed: 12/16/2022] Open
Abstract
Telomere length and dynamics are central to understanding cell aging, genomic instability and cancer. Currently, there are limited guidelines for analyzing telomeric features in 3D using different cellular models. Image processing for telomere analysis is of increasing interest in many fields, however a lack of standardization can make comparisons and reproducibility an issue. Here we provide a user's guide for quantitative immunofluorescence microscopy of telomeres in interphase cells that covers image acquisition, processing and analysis. Strategies for determining telomere size and number are identified using normal human diploid Hs68 fibroblasts. We demonstrate how to accurately determine telomere number, length, volume, and degree of clustering using quantitative immunofluorescence. Using this workflow, we make the unexpected observation that hTERT-immortalized Hs68 cells with longer telomeres have fewer resolvable telomeres in interphase. Rigorous quantification indicates that this is due to telomeric clustering, leading to systematic underestimation of telomere number and overestimation of telomere size.
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Affiliation(s)
- Nancy Adam
- Department of Biochemistry & Molecular Biology, University of Calgary, Calgary, AB Canada
| | - Erin Degelman
- Cumming School of Medicine, University of Calgary, Calgary, AB Canada
| | - Sophie Briggs
- Department of Biochemistry & Molecular Biology, University of Calgary, Calgary, AB Canada
| | - Rima-Marie Wazen
- Live Cell Imaging Laboratory, Cumming School of Medicine, University of Calgary, Calgary, AB Canada
| | - Pina Colarusso
- Live Cell Imaging Laboratory, Cumming School of Medicine, University of Calgary, Calgary, AB Canada
- Department of Physiology & Pharmacology, University of Calgary, Calgary, AB Canada
| | - Karl Riabowol
- Department of Biochemistry & Molecular Biology, University of Calgary, Calgary, AB Canada
- Department of Oncology, University of Calgary, Calgary, AB Canada
| | - Tara Beattie
- Department of Biochemistry & Molecular Biology, University of Calgary, Calgary, AB Canada
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11
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Miné-Hattab J, Taddei A. Physical principles and functional consequences of nuclear compartmentalization in budding yeast. Curr Opin Cell Biol 2019; 58:105-113. [PMID: 30928833 DOI: 10.1016/j.ceb.2019.02.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2018] [Revised: 01/28/2019] [Accepted: 02/20/2019] [Indexed: 12/19/2022]
Abstract
One striking feature of eukaryotic nuclei is the existence of discrete regions, in which specific factors concentrate while others are excluded, thus forming microenvironments with different molecular compositions and biological functions. These domains are often referred to as subcompartments even though they are not membrane enclosed. Despite their functional importance the physical nature of these structures remains largely unknown. Here, we describe how the Saccharomyces cerevisiae nucleus is compartmentalized and discuss possible physical models underlying the formation and maintenance of chromatin associated subcompartments. Focusing on three particular examples, the nucleolus, silencing foci, and repair foci, we discuss the biological implications of these different models as well as possible approaches to challenge them in living cells.
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Affiliation(s)
- Judith Miné-Hattab
- Institut Curi-PSL Research University, CNRS, Sorbonne Université, UMR3664, F-75005, Paris, France
| | - Angela Taddei
- Institut Curi-PSL Research University, CNRS, Sorbonne Université, UMR3664, F-75005, Paris, France.
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12
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Bordelet H, Dubrana K. Keep moving and stay in a good shape to find your homologous recombination partner. Curr Genet 2019; 65:29-39. [PMID: 30097675 PMCID: PMC6342867 DOI: 10.1007/s00294-018-0873-1] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2018] [Revised: 07/31/2018] [Accepted: 08/02/2018] [Indexed: 01/02/2023]
Abstract
Genomic DNA is constantly exposed to damage. Among the lesion in DNA, double-strand breaks (DSB), because they disrupt the two strands of the DNA double helix, are the more dangerous. DSB are repaired through two evolutionary conserved mechanisms: Non-Homologous End Joining (NHEJ) and Homologous Recombination (HR). Whereas NHEJ simply reseals the double helix with no or minimal processing, HR necessitates the formation of a 3'ssDNA through the processing of DSB ends by the resection machinery and relies on the recognition and pairing of this 3'ssDNA tails with an intact homologous sequence. Despite years of active research on HR, the manner by which the two homologous sequences find each other in the crowded nucleus, and how this modulates HR efficiency, only recently emerges. Here, we review recent advances in our understanding of the factors limiting the search of a homologous sequence during HR.
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Affiliation(s)
- Hélène Bordelet
- Laboratoire Instabilité et Organisation Nucléaire, iRCM, IBFJ, DRF, CEA. 2 INSERM, U967. 3 Université Paris Diderot et Paris Saclay, UMR967, Fontenay-aux-roses, 92265, France
| | - Karine Dubrana
- Laboratoire Instabilité et Organisation Nucléaire, iRCM, IBFJ, DRF, CEA. 2 INSERM, U967. 3 Université Paris Diderot et Paris Saclay, UMR967, Fontenay-aux-roses, 92265, France.
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13
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Lin D, Bonora G, Yardımcı GG, Noble WS. Computational methods for analyzing and modeling genome structure and organization. WILEY INTERDISCIPLINARY REVIEWS. SYSTEMS BIOLOGY AND MEDICINE 2019; 11:e1435. [PMID: 30022617 PMCID: PMC6294685 DOI: 10.1002/wsbm.1435] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2017] [Revised: 06/07/2018] [Accepted: 06/16/2018] [Indexed: 12/31/2022]
Abstract
Recent advances in chromosome conformation capture technologies have led to the discovery of previously unappreciated structural features of chromatin. Computational analysis has been critical in detecting these features and thereby helping to uncover the building blocks of genome architecture. Algorithms are being developed to integrate these architectural features to construct better three-dimensional (3D) models of the genome. These computational methods have revealed the importance of 3D genome organization to essential biological processes. In this article, we review the state of the art in analytic and modeling techniques with a focus on their application to answering various biological questions related to chromatin structure. We summarize the limitations of these computational techniques and suggest future directions, including the importance of incorporating multiple sources of experimental data in building a more comprehensive model of the genome. This article is categorized under: Analytical and Computational Methods > Computational Methods Laboratory Methods and Technologies > Genetic/Genomic Methods Models of Systems Properties and Processes > Mechanistic Models.
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Affiliation(s)
- Dejun Lin
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
| | - Giancarlo Bonora
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
| | | | - William S. Noble
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
- Department of Computer Science and Engineering, University of Washington, Seattle, WA, USA
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14
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Ballarino M, Cipriano A, Tita R, Santini T, Desideri F, Morlando M, Colantoni A, Carrieri C, Nicoletti C, Musarò A, Carroll DO, Bozzoni I. Deficiency in the nuclear long noncoding RNA Charme causes myogenic defects and heart remodeling in mice. EMBO J 2018; 37:embj.201899697. [PMID: 30177572 PMCID: PMC6138438 DOI: 10.15252/embj.201899697] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Revised: 07/17/2018] [Accepted: 07/21/2018] [Indexed: 01/03/2023] Open
Abstract
Myogenesis is a highly regulated process that involves the conversion of progenitor cells into multinucleated myofibers. Besides proteins and miRNAs, long noncoding RNAs (lncRNAs) have been shown to participate in myogenic regulatory circuitries. Here, we characterize a murine chromatin‐associated muscle‐specific lncRNA, Charme, which contributes to the robustness of the myogenic program in vitro and in vivo. In myocytes, Charme depletion triggers the disassembly of a specific chromosomal domain and the downregulation of myogenic genes contained therein. Notably, several Charme‐sensitive genes are associated with human cardiomyopathies and Charme depletion in mice results in a peculiar cardiac remodeling phenotype with changes in size, structure, and shape of the heart. Moreover, the existence of an orthologous transcript in human, regulating the same subset of target genes, suggests an important and evolutionarily conserved function for Charme. Altogether, these data describe a new example of a chromatin‐associated lncRNA regulating the robustness of skeletal and cardiac myogenesis.
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Affiliation(s)
- Monica Ballarino
- Department of Biology and Biotechnology Charles Darwin, Sapienza University of Rome, Rome, Italy
| | - Andrea Cipriano
- Department of Biology and Biotechnology Charles Darwin, Sapienza University of Rome, Rome, Italy
| | - Rossella Tita
- Department of Biology and Biotechnology Charles Darwin, Sapienza University of Rome, Rome, Italy
| | - Tiziana Santini
- Center for Life Nano Science@Sapienza, Istituto Italiano di Tecnologia, Rome, Italy
| | - Fabio Desideri
- Department of Biology and Biotechnology Charles Darwin, Sapienza University of Rome, Rome, Italy
| | - Mariangela Morlando
- Department of Biology and Biotechnology Charles Darwin, Sapienza University of Rome, Rome, Italy
| | - Alessio Colantoni
- Department of Biology and Biotechnology Charles Darwin, Sapienza University of Rome, Rome, Italy
| | - Claudia Carrieri
- MRC Centre for Regenerative Medicine, University of Edinburgh, Edinburgh, UK
| | - Carmine Nicoletti
- DAHFMO-Unit of Histology and Medical Embryology, Sapienza University of Rome, Rome, Italy
| | - Antonio Musarò
- Center for Life Nano Science@Sapienza, Istituto Italiano di Tecnologia, Rome, Italy.,DAHFMO-Unit of Histology and Medical Embryology, Sapienza University of Rome, Rome, Italy
| | - Dònal O' Carroll
- MRC Centre for Regenerative Medicine, University of Edinburgh, Edinburgh, UK
| | - Irene Bozzoni
- Department of Biology and Biotechnology Charles Darwin, Sapienza University of Rome, Rome, Italy .,Center for Life Nano Science@Sapienza, Istituto Italiano di Tecnologia, Rome, Italy.,Institute Pasteur Fondazione Cenci-Bolognetti, Sapienza University of Rome, Rome, Italy.,Institute of Molecular Biology and Pathology, CNR, Sapienza University of Rome, Rome, Italy
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15
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Zimmer C, Fabre E. Chromatin mobility upon DNA damage: state of the art and remaining questions. Curr Genet 2018; 65:1-9. [DOI: 10.1007/s00294-018-0852-6] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Revised: 05/30/2018] [Accepted: 06/04/2018] [Indexed: 12/14/2022]
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16
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Mercy G, Mozziconacci J, Scolari VF, Yang K, Zhao G, Thierry A, Luo Y, Mitchell LA, Shen M, Shen Y, Walker R, Zhang W, Wu Y, Xie ZX, Luo Z, Cai Y, Dai J, Yang H, Yuan YJ, Boeke JD, Bader JS, Muller H, Koszul R. 3D organization of synthetic and scrambled chromosomes. Science 2017; 355:355/6329/eaaf4597. [PMID: 28280150 DOI: 10.1126/science.aaf4597] [Citation(s) in RCA: 89] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Accepted: 02/01/2017] [Indexed: 11/02/2022]
Abstract
Although the design of the synthetic yeast genome Sc2.0 is highly conservative with respect to gene content, the deletion of several classes of repeated sequences and the introduction of thousands of designer changes may affect genome organization and potentially alter cellular functions. We report here the Hi-C-determined three-dimensional (3D) conformations of Sc2.0 chromosomes. The absence of repeats leads to a smoother contact pattern and more precisely tractable chromosome conformations, and the large-scale genomic organization is globally unaffected by the presence of synthetic chromosome(s). Two exceptions are synIII, which lacks the silent mating-type cassettes, and synXII, specifically when the ribosomal DNA is moved to another chromosome. We also exploit the contact maps to detect rearrangements induced in SCRaMbLE (synthetic chromosome rearrangement and modification by loxP-mediated evolution) strains.
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Affiliation(s)
- Guillaume Mercy
- Spatial Regulation of Genomes, Department of Genomes and Genetics, Institut Pasteur, Paris 75015, France.,UMR3525, Centre National de la Recherche Scientifique (CNRS), Paris 75015, France.,Sorbonne Universités, Université Pierre et Marie Curie (Université Paris 6), Paris 75005, France
| | - Julien Mozziconacci
- Laboratoire de Physique Théorique de la Matière Condensée, CNRS UMR7600, Université Pierre et Marie Curie (Université Paris 6), Sorbonne Universités, Paris, France
| | - Vittore F Scolari
- Spatial Regulation of Genomes, Department of Genomes and Genetics, Institut Pasteur, Paris 75015, France.,UMR3525, Centre National de la Recherche Scientifique (CNRS), Paris 75015, France
| | - Kun Yang
- Department of Biomedical Engineering and High-Throughput Biology Center, Whiting School of Engineering, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Guanghou Zhao
- Key Laboratory for Industrial Biocatalysis (Ministry of Education), Key Laboratory of Bioinformatics (Ministry of Education), Center for Synthetic and Systems Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Agnès Thierry
- Spatial Regulation of Genomes, Department of Genomes and Genetics, Institut Pasteur, Paris 75015, France.,UMR3525, Centre National de la Recherche Scientifique (CNRS), Paris 75015, France
| | - Yisha Luo
- School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3BF, UK
| | - Leslie A Mitchell
- Institute for Systems Genetics and Department of Biochemistry and Molecular Pharmacology, Langone Medical Center, New York University, New York, NY 10016, USA
| | - Michael Shen
- Institute for Systems Genetics and Department of Biochemistry and Molecular Pharmacology, Langone Medical Center, New York University, New York, NY 10016, USA
| | - Yue Shen
- BGI-Shenzhen, Shenzhen 518083, China.,BGI-Qingdao, Qingdao 266555, China.,School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3BF, UK
| | - Roy Walker
- School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3BF, UK
| | - Weimin Zhang
- Key Laboratory for Industrial Biocatalysis (Ministry of Education), Key Laboratory of Bioinformatics (Ministry of Education), Center for Synthetic and Systems Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Yi Wu
- Key Laboratory of Systems Bioengineering (Ministry of Education), SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
| | - Ze-Xiong Xie
- Key Laboratory of Systems Bioengineering (Ministry of Education), SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
| | - Zhouqing Luo
- Key Laboratory for Industrial Biocatalysis (Ministry of Education), Key Laboratory of Bioinformatics (Ministry of Education), Center for Synthetic and Systems Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Yizhi Cai
- School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3BF, UK
| | - Junbiao Dai
- Key Laboratory for Industrial Biocatalysis (Ministry of Education), Key Laboratory of Bioinformatics (Ministry of Education), Center for Synthetic and Systems Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Huanming Yang
- James D. Watson Institute of Genome Sciences, Hangzhou 310058, China.,BGI-Shenzhen, Shenzhen 518083, China
| | - Ying-Jin Yuan
- Key Laboratory of Systems Bioengineering (Ministry of Education), SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
| | - Jef D Boeke
- Institute for Systems Genetics and Department of Biochemistry and Molecular Pharmacology, Langone Medical Center, New York University, New York, NY 10016, USA
| | - Joel S Bader
- Department of Biomedical Engineering and High-Throughput Biology Center, Whiting School of Engineering, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Héloïse Muller
- Spatial Regulation of Genomes, Department of Genomes and Genetics, Institut Pasteur, Paris 75015, France. .,UMR3525, Centre National de la Recherche Scientifique (CNRS), Paris 75015, France
| | - Romain Koszul
- Spatial Regulation of Genomes, Department of Genomes and Genetics, Institut Pasteur, Paris 75015, France. .,UMR3525, Centre National de la Recherche Scientifique (CNRS), Paris 75015, France
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17
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Kim S, Liachko I, Brickner DG, Cook K, Noble WS, Brickner JH, Shendure J, Dunham MJ. The dynamic three-dimensional organization of the diploid yeast genome. eLife 2017; 6. [PMID: 28537556 PMCID: PMC5476426 DOI: 10.7554/elife.23623] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2016] [Accepted: 05/22/2017] [Indexed: 12/14/2022] Open
Abstract
The budding yeast Saccharomyces cerevisiae is a long-standing model for the three-dimensional organization of eukaryotic genomes. However, even in this well-studied model, it is unclear how homolog pairing in diploids or environmental conditions influence overall genome organization. Here, we performed high-throughput chromosome conformation capture on diverged Saccharomyces hybrid diploids to obtain the first global view of chromosome conformation in diploid yeasts. After controlling for the Rabl-like orientation using a polymer model, we observe significant homolog proximity that increases in saturated culture conditions. Surprisingly, we observe a localized increase in homologous interactions between the HAS1-TDA1 alleles specifically under galactose induction and saturated growth. This pairing is accompanied by relocalization to the nuclear periphery and requires Nup2, suggesting a role for nuclear pore complexes. Together, these results reveal that the diploid yeast genome has a dynamic and complex 3D organization. DOI:http://dx.doi.org/10.7554/eLife.23623.001 Most of the DNA in human, yeast and other eukaryotic cells is packaged into long thread-like structures called chromosomes within a compartment of the cell called the nucleus. The chromosomes are folded to fit inside the nucleus and this organization influences how the DNA is read, copied, and repaired. The folding of chromosomes must be robust in order to protect the organism’s genetic material and yet be flexible enough to allow different parts of the DNA to be accessed in response to different signals. A biochemical technique called Hi-C can be used to detect the points of contact between different regions of a chromosome and between different chromosomes, thereby providing information on how the chromosomes are folded and arranged inside the nucleus. However, most animal cells contain two copies of each chromosome, and the Hi-C method is not able to distinguish between identical copies of chromosomes. As such, it remains unclear how much the chromosomes that can form pairs actually stick together in a cell’s nucleus. Unlike humans and most organisms, two distantly related budding yeast species can mate to produce a “hybrid” in which the chromosome copies can easily be distinguished from each other. Kim et al. now use Hi-C to analyze how chromosomes are organized in hybrid budding yeast cells. The experiments reveal that the copies of a chromosome contact each other more frequently than would be expected by chance. This is especially true for certain chromosomal regions and in hybrid yeast cells that are running out of their preferred nutrient, glucose. In these cells, the regions of both copies of chromosome 13 near a gene called TDA1 are pulled to the edge of the nucleus, which helps the copies to pair up and the gene to become active. The protein encoded by TDA1 then helps turn on other genes that allow the yeast to use nutrients other than glucose. Many questions remain about how and why DNA is organized the way it is, both in yeast and in other organisms. These findings will help guide future experiments testing how the two copies of each chromosome pair, as well as what purpose, if any, this pairing might serve for the cell. A better understanding of the fundamental process of DNA organization and its implications may ultimately lead to improved treatments for genetic diseases including developmental disorders and cancers. DOI:http://dx.doi.org/10.7554/eLife.23623.002
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Affiliation(s)
- Seungsoo Kim
- Department of Genome Sciences, University of Washington, Seattle, United States
| | - Ivan Liachko
- Department of Genome Sciences, University of Washington, Seattle, United States
| | - Donna G Brickner
- Department of Molecular Biosciences, Northwestern University, Evanston, United States
| | - Kate Cook
- Department of Genome Sciences, University of Washington, Seattle, United States
| | - William S Noble
- Department of Genome Sciences, University of Washington, Seattle, United States
| | - Jason H Brickner
- Department of Molecular Biosciences, Northwestern University, Evanston, United States
| | - Jay Shendure
- Department of Genome Sciences, University of Washington, Seattle, United States.,Howard Hughes Medical Institute, University of Washington, Seattle, United States
| | - Maitreya J Dunham
- Department of Genome Sciences, University of Washington, Seattle, United States
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18
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The Nuts and Bolts of Transcriptionally Silent Chromatin in Saccharomyces cerevisiae. Genetics 2017; 203:1563-99. [PMID: 27516616 DOI: 10.1534/genetics.112.145243] [Citation(s) in RCA: 88] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Accepted: 05/30/2016] [Indexed: 12/31/2022] Open
Abstract
Transcriptional silencing in Saccharomyces cerevisiae occurs at several genomic sites including the silent mating-type loci, telomeres, and the ribosomal DNA (rDNA) tandem array. Epigenetic silencing at each of these domains is characterized by the absence of nearly all histone modifications, including most prominently the lack of histone H4 lysine 16 acetylation. In all cases, silencing requires Sir2, a highly-conserved NAD(+)-dependent histone deacetylase. At locations other than the rDNA, silencing also requires additional Sir proteins, Sir1, Sir3, and Sir4 that together form a repressive heterochromatin-like structure termed silent chromatin. The mechanisms of silent chromatin establishment, maintenance, and inheritance have been investigated extensively over the last 25 years, and these studies have revealed numerous paradigms for transcriptional repression, chromatin organization, and epigenetic gene regulation. Studies of Sir2-dependent silencing at the rDNA have also contributed to understanding the mechanisms for maintaining the stability of repetitive DNA and regulating replicative cell aging. The goal of this comprehensive review is to distill a wide array of biochemical, molecular genetic, cell biological, and genomics studies down to the "nuts and bolts" of silent chromatin and the processes that yield transcriptional silencing.
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19
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Spichal M, Fabre E. The Emerging Role of the Cytoskeleton in Chromosome Dynamics. Front Genet 2017; 8:60. [PMID: 28580009 PMCID: PMC5437106 DOI: 10.3389/fgene.2017.00060] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2017] [Accepted: 04/28/2017] [Indexed: 01/15/2023] Open
Abstract
Chromosomes underlie a dynamic organization that fulfills functional roles in processes like transcription, DNA repair, nuclear envelope stability, and cell division. Chromosome dynamics depend on chromosome structure and cannot freely diffuse. Furthermore, chromosomes interact closely with their surrounding nuclear environment, which further constrains chromosome dynamics. Recently, several studies enlighten that cytoskeletal proteins regulate dynamic chromosome organization. Cytoskeletal polymers that include actin filaments, microtubules and intermediate filaments can connect to the nuclear envelope via Linker of the Nucleoskeleton and Cytoskeleton (LINC) complexes and transfer forces onto chromosomes inside the nucleus. Monomers of these cytoplasmic polymers and related proteins can also enter the nucleus and play different roles in the interior of the nucleus than they do in the cytoplasm. Nuclear cytoskeletal proteins can act as chromatin remodelers alone or in complexes with other nuclear proteins. They can also act as transcription factors. Many of these mechanisms have been conserved during evolution, indicating that the cytoskeletal regulation of chromosome dynamics is an essential process. In this review, we discuss the different influences of cytoskeletal proteins on chromosome dynamics by focusing on the well-studied model organism budding yeast.
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Affiliation(s)
- Maya Spichal
- Department of Genetics, University of North Carolina, Chapel HillNC, United States
| | - Emmanuelle Fabre
- Equipe Biologie et Dynamique des Chromosomes, Institut Universitaire d'Hématologie, CNRS UMR 7212, INSERM U944, Hôpital St. Louis 1Paris, France
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20
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Rai U, Najm F, Tartakoff AM. Nucleolar asymmetry and the importance of septin integrity upon cell cycle arrest. PLoS One 2017; 12:e0174306. [PMID: 28339487 PMCID: PMC5365125 DOI: 10.1371/journal.pone.0174306] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2016] [Accepted: 03/07/2017] [Indexed: 12/31/2022] Open
Abstract
Cell cycle arrest can be imposed by inactivating the anaphase promoting complex (APC). In S. cerevisiae this arrest has been reported to stabilize a metaphase-like intermediate in which the nuclear envelope spans the bud neck, while chromatin repeatedly translocates between the mother and bud domains. The present investigation was undertaken to learn how other features of nuclear organization are affected upon depletion of the APC activator, Cdc20. We observe that the spindle pole bodies and the spindle repeatedly translocate across the narrow orifice at the level of the neck. Nevertheless, we find that the nucleolus (organized around rDNA repeats on the long right arm of chromosome XII) remains in the mother domain, marking the polarity of the nucleus. Accordingly, chromosome XII is polarized: TelXIIR remains in the mother domain and its centromere is predominantly located in the bud domain. In order to learn why the nucleolus remains in the mother domain, we studied the impact of inhibiting rRNA synthesis in arrested cells. We observed that this fragments the nucleolus and that these fragments entered the bud domain. Taken together with earlier observations, the restriction of the nucleolus to the mother domain therefore can be attributed to its massive structure. We also observed that inactivation of septins allowed arrested cells to complete the cell cycle, that the alternative APC activator, Cdh1, was required for completion of the cell cycle and that induction of Cdh1 itself caused arrested cells to progress to the end of the cell cycle.
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Affiliation(s)
- Urvashi Rai
- Cell Biology Program/Department of Molecular and Microbiology, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Fadi Najm
- Division of Medical Sciences, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Alan M. Tartakoff
- Department of Pathology, Case Western Reserve University, Cleveland, Ohio, United States of America
- * E-mail:
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21
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Abstract
Chromosomes underlie a dynamic organization that fulfills functional roles in processes like transcription, DNA repair, nuclear envelope stability, and cell division. Chromosome dynamics depend on chromosome structure and cannot freely diffuse. Furthermore, chromosomes interact closely with their surrounding nuclear environment, which further constrains chromosome dynamics. Recently, several studies enlighten that cytoskeletal proteins regulate dynamic chromosome organization. Cytoskeletal polymers that include actin filaments, microtubules and intermediate filaments can connect to the nuclear envelope via Linker of the Nucleoskeleton and Cytoskeleton (LINC) complexes and transfer forces onto chromosomes inside the nucleus. Monomers of these cytoplasmic polymers and related proteins can also enter the nucleus and play different roles in the interior of the nucleus than they do in the cytoplasm. Nuclear cytoskeletal proteins can act as chromatin remodelers alone or in complexes with other nuclear proteins. They can also act as transcription factors. Many of these mechanisms have been conserved during evolution, indicating that the cytoskeletal regulation of chromosome dynamics is an essential process. In this review, we discuss the different influences of cytoskeletal proteins on chromosome dynamics by focusing on the well-studied model organism budding yeast.
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Affiliation(s)
- Maya Spichal
- Department of Genetics, University of North Carolina, Chapel HillNC, United States
| | - Emmanuelle Fabre
- Equipe Biologie et Dynamique des Chromosomes, Institut Universitaire d'Hématologie, CNRS UMR 7212, INSERM U944, Hôpital St. Louis 1Paris, France
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22
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Methods to Study the Atypical Roles of DNA Repair and SMC Proteins in Gene Silencing. Methods Mol Biol 2016. [PMID: 27797079 DOI: 10.1007/978-1-4939-6545-8_10] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2023]
Abstract
Silenced heterochromatin influences all nuclear processes including chromosome structure, nuclear organization, transcription, replication, and repair. Proteins that mediate silencing affect all of these nuclear processes. Similarly proteins involved in replication, repair, and chromosome structure play a role in the formation and maintenance of silenced heterochromatin. In this chapter we describe a handful of simple tools and methods that can be used to study the atypical role of proteins in gene silencing.
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23
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Abstract
Chromosomes are folded into cells in a nonrandom fashion, with particular genetic loci occupying distinct spatial regions. This observation raises the question of whether the spatial organization of a chromosome governs its functions, such as recombination or transcription. We consider this general question in the specific context of mating-type switching in budding yeast, which is a model system for homologous recombination. Mating-type switching is induced by a DNA double-strand break (DSB) at the MAT locus on chromosome III, followed by homologous recombination between the cut MAT locus and one of two donor loci (HMLα and HMRa), located on the same chromosome. Previous studies have suggested that in MATa cells after the DSB is induced chromosome III undergoes refolding, which directs the MAT locus to recombine with HMLα. Here, we propose a quantitative model of mating-type switching predicated on the assumption of DSB-induced chromosome refolding, which also takes into account the previously measured stochastic dynamics and polymer nature of yeast chromosomes. Using quantitative fluorescence microscopy, we measure changes in the distance between the donor (HMLα) and MAT loci after the DSB and find agreement with the theory. Predictions of the theory also agree with measurements of changes in the use of HMLα as the donor, when we perturb the refolding of chromosome III. These results establish refolding of yeast chromosome III as a key driving force in MAT switching and provide an example of a cell regulating the spatial organization of its chromosome so as to direct homology search during recombination.
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24
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Lefrançois P, Rockmill B, Xie P, Roeder GS, Snyder M. Multiple Pairwise Analysis of Non-homologous Centromere Coupling Reveals Preferential Chromosome Size-Dependent Interactions and a Role for Bouquet Formation in Establishing the Interaction Pattern. PLoS Genet 2016; 12:e1006347. [PMID: 27768699 PMCID: PMC5074576 DOI: 10.1371/journal.pgen.1006347] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Accepted: 09/07/2016] [Indexed: 12/26/2022] Open
Abstract
During meiosis, chromosomes undergo a homology search in order to locate their homolog to form stable pairs and exchange genetic material. Early in prophase, chromosomes associate in mostly non-homologous pairs, tethered only at their centromeres. This phenomenon, conserved through higher eukaryotes, is termed centromere coupling in budding yeast. Both initiation of recombination and the presence of homologs are dispensable for centromere coupling (occurring in spo11 mutants and haploids induced to undergo meiosis) but the presence of the synaptonemal complex (SC) protein Zip1 is required. The nature and mechanism of coupling have yet to be elucidated. Here we present the first pairwise analysis of centromere coupling in an effort to uncover underlying rules that may exist within these non-homologous interactions. We designed a novel chromosome conformation capture (3C)-based assay to detect all possible interactions between non-homologous yeast centromeres during early meiosis. Using this variant of 3C-qPCR, we found a size-dependent interaction pattern, in which chromosomes assort preferentially with chromosomes of similar sizes, in haploid and diploid spo11 cells, but not in a coupling-defective mutant (spo11 zip1 haploid and diploid yeast). This pattern is also observed in wild-type diploids early in meiosis but disappears as meiosis progresses and homologous chromosomes pair. We found no evidence to support the notion that ancestral centromere homology plays a role in pattern establishment in S. cerevisiae post-genome duplication. Moreover, we found a role for the meiotic bouquet in establishing the size dependence of centromere coupling, as abolishing bouquet (using the bouquet-defective spo11 ndj1 mutant) reduces it. Coupling in spo11 ndj1 rather follows telomere clustering preferences. We propose that a chromosome size preference for centromere coupling helps establish efficient homolog recognition.
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Affiliation(s)
- Philippe Lefrançois
- Department of Molecular, Cellular and Developmental Biology Yale University New Haven, United States of America
- Faculty of Medicine University of Montreal, Montreal, CANADA
- * E-mail: (PL); (MS)
| | - Beth Rockmill
- Department of Molecular, Cellular and Developmental Biology Yale University New Haven, United States of America
- Department of Molecular and Cell Biology University of California Berkeley, Berkeley, United States of America
| | - Pingxing Xie
- Faculty of Medicine McGill University Montreal, CANADA
| | - G. Shirleen Roeder
- Department of Molecular, Cellular and Developmental Biology Yale University New Haven, United States of America
| | - Michael Snyder
- Department of Genetics Stanford University School of Medicine Stanford, United States of America
- * E-mail: (PL); (MS)
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25
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Laporte D, Courtout F, Tollis S, Sagot I. Quiescent Saccharomyces cerevisiae forms telomere hyperclusters at the nuclear membrane vicinity through a multifaceted mechanism involving Esc1, the Sir complex, and chromatin condensation. Mol Biol Cell 2016; 27:1875-84. [PMID: 27122604 PMCID: PMC4907721 DOI: 10.1091/mbc.e16-01-0069] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2016] [Accepted: 04/20/2016] [Indexed: 01/09/2023] Open
Abstract
Upon quiescence entry, yeast cells assemble telomere hyperclusters. These structures localize to the nuclear membrane in an Esc1-dependent manner and assemble through the combined action of the Sir complex, deacetylation of H4K16, the binding of the linker histone H1, and condensin. Like other eukaryotes, Saccharomyces cerevisiae spatially organizes its chromosomes within the nucleus. In G1 phase, the yeast’s 32 telomeres are clustered into 6–10 foci that dynamically interact with the nuclear membrane. Here we show that, when cells leave the division cycle and enter quiescence, telomeres gather into two to three hyperclusters at the nuclear membrane vicinity. This localization depends on Esc1 but not on the Ku proteins. Telomere hypercluster formation requires the Sir complex but is independent of the nuclear microtubule bundle that specifically assembles in quiescent cells. Importantly, mutants deleted for the linker histone H1 Hho1 or defective in condensin activity or affected for histone H4 Lys-16 deacetylation are impaired, at least in part, for telomere hypercluster formation in quiescence, suggesting that this process involves chromosome condensation. Finally, we establish that telomere hypercluster formation is not necessary for quiescence establishment, maintenance, and exit, raising the question of the physiological raison d’être of this nuclear reorganization.
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Affiliation(s)
- Damien Laporte
- Université de Bordeaux-Institut de Biochimie et Génétique Cellulaires, 33000 Bordeaux, France CNRS-UMR5095 Bordeaux, 33077 Bordeaux cedex, France
| | - Fabien Courtout
- Université de Bordeaux-Institut de Biochimie et Génétique Cellulaires, 33000 Bordeaux, France CNRS-UMR5095 Bordeaux, 33077 Bordeaux cedex, France
| | - Sylvain Tollis
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh EH93BF, United Kingdom
| | - Isabelle Sagot
- Université de Bordeaux-Institut de Biochimie et Génétique Cellulaires, 33000 Bordeaux, France CNRS-UMR5095 Bordeaux, 33077 Bordeaux cedex, France
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26
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Spichal M, Brion A, Herbert S, Cournac A, Marbouty M, Zimmer C, Koszul R, Fabre E. Evidence for a dual role of actin in regulating chromosome organization and dynamics in yeast. J Cell Sci 2016; 129:681-92. [PMID: 26763908 DOI: 10.1242/jcs.175745] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2015] [Accepted: 01/05/2016] [Indexed: 01/07/2023] Open
Abstract
Eukaryotic chromosomes undergo movements that are involved in the regulation of functional processes such as DNA repair. To better understand the origin of these movements, we used fluorescence microscopy, image analysis and chromosome conformation capture to quantify the actin contribution to chromosome movements and interactions in budding yeast. We show that both the cytoskeletal and nuclear actin drive local chromosome movements, independently of Csm4, a putative LINC protein. Inhibition of actin polymerization reduces subtelomere dynamics, resulting in more confined territories and enrichment in subtelomeric contacts. Artificial tethering of actin to nuclear pores increased both nuclear pore complex (NPC) and subtelomere motion. Chromosome loci that were positioned away from telomeres exhibited reduced motion in the presence of an actin polymerization inhibitor but were unaffected by the lack of Csm4. We further show that actin was required for locus mobility that was induced by targeting the chromatin-remodeling protein Ino80. Correlated with this, DNA repair by homologous recombination was less efficient. Overall, interphase chromosome dynamics are modulated by the additive effects of cytoskeletal actin through forces mediated by the nuclear envelope and nuclear actin, probably through the function of actin in chromatin-remodeling complexes.
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Affiliation(s)
- Maya Spichal
- INSERM UMR 944, Equipe Biologie et Dynamique des Chromosomes, Institut Universitaire d'Hématologie, Hôpital St. Louis 1, Avenue Claude Vellefaux, Paris 75010, France CNRS, UMR 7212, Paris 75010, France Université Paris Diderot, Sorbonne Paris Cité, Paris 75010, France Institut Pasteur, Groupe Régulation Spatiale des Génomes, Paris 75015, France CNRS, UMR 3525, Paris 75015, France Sorbonne Universités, UPMC Université Paris 6, Paris 75005, France
| | - Alice Brion
- INSERM UMR 944, Equipe Biologie et Dynamique des Chromosomes, Institut Universitaire d'Hématologie, Hôpital St. Louis 1, Avenue Claude Vellefaux, Paris 75010, France CNRS, UMR 7212, Paris 75010, France Université Paris Diderot, Sorbonne Paris Cité, Paris 75010, France
| | - Sébastien Herbert
- Institut Pasteur, Unité Imagerie et Modélisation, Paris 75015, France CNRS, URA 2582, Paris 75015, France
| | - Axel Cournac
- Institut Pasteur, Groupe Régulation Spatiale des Génomes, Paris 75015, France CNRS, UMR 3525, Paris 75015, France
| | - Martial Marbouty
- Institut Pasteur, Groupe Régulation Spatiale des Génomes, Paris 75015, France CNRS, UMR 3525, Paris 75015, France
| | - Christophe Zimmer
- Institut Pasteur, Unité Imagerie et Modélisation, Paris 75015, France CNRS, URA 2582, Paris 75015, France
| | - Romain Koszul
- Institut Pasteur, Groupe Régulation Spatiale des Génomes, Paris 75015, France CNRS, UMR 3525, Paris 75015, France
| | - Emmanuelle Fabre
- INSERM UMR 944, Equipe Biologie et Dynamique des Chromosomes, Institut Universitaire d'Hématologie, Hôpital St. Louis 1, Avenue Claude Vellefaux, Paris 75010, France CNRS, UMR 7212, Paris 75010, France Université Paris Diderot, Sorbonne Paris Cité, Paris 75010, France Institut Pasteur, Groupe Régulation Spatiale des Génomes, Paris 75015, France CNRS, UMR 3525, Paris 75015, France
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27
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Rutledge MT, Russo M, Belton JM, Dekker J, Broach JR. The yeast genome undergoes significant topological reorganization in quiescence. Nucleic Acids Res 2015. [PMID: 26202961 PMCID: PMC4787801 DOI: 10.1093/nar/gkv723] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
Abstract
We have examined the three-dimensional organization of the yeast genome during quiescence by a chromosome capture technique as a means of understanding how genome organization changes during development. For exponentially growing cells we observe high levels of inter-centromeric interaction but otherwise a predominance of intrachromosomal interactions over interchromosomal interactions, consistent with aggregation of centromeres at the spindle pole body and compartmentalization of individual chromosomes within the nucleoplasm. Three major changes occur in the organization of the quiescent cell genome. First, intrachromosomal associations increase at longer distances in quiescence as compared to growing cells. This suggests that chromosomes undergo condensation in quiescence, which we confirmed by microscopy by measurement of the intrachromosomal distances between two sites on one chromosome. This compaction in quiescence requires the condensin complex. Second, inter-centromeric interactions decrease, consistent with prior data indicating that centromeres disperse along an array of microtubules during quiescence. Third, inter-telomeric interactions significantly increase in quiescence, an observation also confirmed by direct measurement. Thus, survival during quiescence is associated with substantial topological reorganization of the genome.
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Affiliation(s)
- Mark T Rutledge
- Department of Biochemistry and Molecular Biology, Penn State College of Medicine, Hershey, PA 17033, USA Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA
| | - Mariano Russo
- Department of Biochemistry and Molecular Biology, Penn State College of Medicine, Hershey, PA 17033, USA
| | - Jon-Matthew Belton
- Program in Systems Biology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Job Dekker
- Program in Systems Biology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - James R Broach
- Department of Biochemistry and Molecular Biology, Penn State College of Medicine, Hershey, PA 17033, USA
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Gong K, Tjong H, Zhou XJ, Alber F. Comparative 3D genome structure analysis of the fission and the budding yeast. PLoS One 2015; 10:e0119672. [PMID: 25799503 PMCID: PMC4370715 DOI: 10.1371/journal.pone.0119672] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2014] [Accepted: 01/15/2015] [Indexed: 11/18/2022] Open
Abstract
We studied the 3D structural organization of the fission yeast genome, which emerges from the tethering of heterochromatic regions in otherwise randomly configured chromosomes represented as flexible polymer chains in an nuclear environment. This model is sufficient to explain in a statistical manner many experimentally determined distinctive features of the fission yeast genome, including chromatin interaction patterns from Hi-C experiments and the co-locations of functionally related and co-expressed genes, such as genes expressed by Pol-III. Our findings demonstrate that some previously described structure-function correlations can be explained as a consequence of random chromatin collisions driven by a few geometric constraints (mainly due to centromere-SPB and telomere-NE tethering) combined with the specific gene locations in the chromosome sequence. We also performed a comparative analysis between the fission and budding yeast genome structures, for which we previously detected a similar organizing principle. However, due to the different chromosome sizes and numbers, substantial differences are observed in the 3D structural genome organization between the two species, most notably in the nuclear locations of orthologous genes, and the extent of nuclear territories for genes and chromosomes. However, despite those differences, remarkably, functional similarities are maintained, which is evident when comparing spatial clustering of functionally related genes in both yeasts. Functionally related genes show a similar spatial clustering behavior in both yeasts, even though their nuclear locations are largely different between the yeast species.
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Affiliation(s)
- Ke Gong
- Molecular and Computational Biology, Department of Biological Sciences, University of Southern California, 1050 Childs Way, Los Angeles, CA 90089, United States of America
| | - Harianto Tjong
- Molecular and Computational Biology, Department of Biological Sciences, University of Southern California, 1050 Childs Way, Los Angeles, CA 90089, United States of America
| | - Xianghong Jasmine Zhou
- Molecular and Computational Biology, Department of Biological Sciences, University of Southern California, 1050 Childs Way, Los Angeles, CA 90089, United States of America
- * E-mail: (FA); (XJZ)
| | - Frank Alber
- Molecular and Computational Biology, Department of Biological Sciences, University of Southern California, 1050 Childs Way, Los Angeles, CA 90089, United States of America
- * E-mail: (FA); (XJZ)
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29
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Gerhold CB, Hauer MH, Gasser SM. INO80-C and SWR-C: Guardians of the Genome. J Mol Biol 2015; 427:637-51. [DOI: 10.1016/j.jmb.2014.10.015] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2014] [Revised: 10/13/2014] [Accepted: 10/17/2014] [Indexed: 01/01/2023]
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Capurso D, Segal MR. Distance-based assessment of the localization of functional annotations in 3D genome reconstructions. BMC Genomics 2014; 15:992. [PMID: 25407917 PMCID: PMC4254257 DOI: 10.1186/1471-2164-15-992] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2014] [Accepted: 11/04/2014] [Indexed: 11/20/2022] Open
Abstract
Background Recent studies used the contact data or three-dimensional (3D) genome reconstructions from Hi-C (chromosome conformation capture with next-generation sequencing) to assess the co-localization of functional genomic annotations in the nucleus. These analyses dichotomized data point pairs belonging to a functional annotation as “close” or “far” based on some threshold and then tested for enrichment of “close” pairs. We propose an alternative approach that avoids dichotomization of the data and instead directly estimates the significance of distances within the 3D reconstruction. Results We applied this approach to 3D genome reconstructions for Plasmodium falciparum, the causative agent of malaria, and Saccharomyces cerevisiae and compared the results to previous approaches. We found significant 3D co-localization of centromeres, telomeres, virulence genes, and several sets of genes with developmentally regulated expression in P. falciparum; and significant 3D co-localization of centromeres and long terminal repeats in S. cerevisiae. Additionally, we tested the experimental observation that telomeres form three to seven clusters in P. falciparum and S. cerevisiae. Applying affinity propagation clustering to telomere coordinates in the 3D reconstructions yielded six telomere clusters for both organisms. Conclusions Distance-based assessment replicated key findings, while avoiding dichotomization of the data (which previously yielded threshold-sensitive results). Electronic supplementary material The online version of this article (doi:10.1186/1471-2164-15-992) contains supplementary material, which is available to authorized users.
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Affiliation(s)
| | - Mark R Segal
- Department of Epidemiology and Biostatistics, University of California, San Francisco, CA 94107, USA.
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31
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Churikov D, Charifi F, Simon MN, Géli V. Rad59-facilitated acquisition of Y' elements by short telomeres delays the onset of senescence. PLoS Genet 2014; 10:e1004736. [PMID: 25375789 PMCID: PMC4222662 DOI: 10.1371/journal.pgen.1004736] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2014] [Accepted: 09/05/2014] [Indexed: 12/25/2022] Open
Abstract
Telomerase-negative yeasts survive via one of the two Rad52-dependent recombination pathways, which have distinct genetic requirements. Although the telomere pattern of type I and type II survivors is well characterized, the mechanistic details of short telomere rearrangement into highly evolved pattern observed in survivors are still missing. Here, we analyze immediate events taking place at the abruptly shortened VII-L and native telomeres. We show that short telomeres engage in pairing with internal Rap1-bound TG1–3-like tracts present between subtelomeric X and Y′ elements, which is followed by BIR-mediated non-reciprocal translocation of Y′ element and terminal TG1–3 repeats from the donor end onto the shortened telomere. We found that choice of the Y′ donor was not random, since both engineered telomere VII-L and native VI-R acquired Y′ elements from partially overlapping sets of specific chromosome ends. Although short telomere repair was associated with transient delay in cell divisions, Y′ translocation on native telomeres did not require Mec1-dependent checkpoint. Furthermore, the homeologous pairing between the terminal TG1–3 repeats at VII-L and internal repeats on other chromosome ends was largely independent of Rad51, but instead it was facilitated by Rad59 that stimulates Rad52 strand annealing activity. Therefore, Y′ translocation events taking place during presenescence are genetically separable from Rad51-dependent Y′ amplification process that occurs later during type I survivor formation. We show that Rad59-facilitated Y′ translocations on X-only telomeres delay the onset of senescence while preparing ground for type I survivor formation. In humans, telomerase is expressed in the germline and stem, but is repressed in somatic cells, which limits replicative lifespan of the latter. To unleash cell proliferation, telomerase is reactivated in most human cancers, but some cancer cells employ alternative lengthening of telomeres (ALT) based on homologous recombination (HR) to escape senescence. Recombination-based telomere maintenance similar to ALT was originally discovered in budding yeast deficient in telomerase activity. Two types of telomere arrangement that depend on two genetically distinct HR pathways (RAD51- and RAD59-dependent) were identified in post-senescent survivors, but the transition to telomere maintenance by HR is poorly understood. Here, we show that one of the earliest steps of short telomere rearrangement in telomerase-negative yeast is directly related to the “short telomere rescue pathway” proposed 20 years ago by Lundblad and Blackburn, which culminates in the acquisition of subtelomeric Y′ element by shortened telomere. We found that this telomere rearrangement depends on Rad52 strand annealing activity stimulated by Rad59, thus it is distinct from Rad51-dependent Y′ amplification process observed in type I survivors. We show that continuous repair of critically short telomeres in telomerase-negative cells delays the onset of senescence and prepares the ground for telomere maintenance by HR.
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Affiliation(s)
- Dmitri Churikov
- Marseille Cancer Research Center (CRCM), U1068 Inserm, UMR7258 CNRS, Aix Marseille University, Institut Paoli-Calmettes, LNCC (Equipe labellisée), Marseille, France
| | - Ferose Charifi
- Marseille Cancer Research Center (CRCM), U1068 Inserm, UMR7258 CNRS, Aix Marseille University, Institut Paoli-Calmettes, LNCC (Equipe labellisée), Marseille, France
| | - Marie-Noëlle Simon
- Marseille Cancer Research Center (CRCM), U1068 Inserm, UMR7258 CNRS, Aix Marseille University, Institut Paoli-Calmettes, LNCC (Equipe labellisée), Marseille, France
| | - Vincent Géli
- Marseille Cancer Research Center (CRCM), U1068 Inserm, UMR7258 CNRS, Aix Marseille University, Institut Paoli-Calmettes, LNCC (Equipe labellisée), Marseille, France
- * E-mail:
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Sumoylation and transcription regulation at nuclear pores. Chromosoma 2014; 124:45-56. [PMID: 25171917 PMCID: PMC4339684 DOI: 10.1007/s00412-014-0481-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Revised: 07/16/2014] [Accepted: 07/17/2014] [Indexed: 01/22/2023]
Abstract
Increasing evidence indicates that besides promoters, enhancers, and epigenetic modifications, nuclear organization is another parameter contributing to optimal control of gene expression. Although differences between species exist, the influence of gene positioning on expression seems to be a conserved feature from yeast to Drosophila and mammals. The nuclear periphery is one of the nuclear compartments implicated in gene regulation. It consists of the nuclear envelope (NE) and the nuclear pore complexes (NPC), which have distinct roles in the control of gene expression. The NPC has recently been shown to tether proteins involved in the sumoylation pathway. Here, we will focus on the importance of gene positioning and NPC-linked sumoylation/desumoylation in transcription regulation. We will mainly discuss observations made in the yeast Saccharomyces cerevisiae model system and highlight potential parallels in metazoan species.
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Effect of chromosome tethering on nuclear organization in yeast. PLoS One 2014; 9:e102474. [PMID: 25020108 PMCID: PMC4096926 DOI: 10.1371/journal.pone.0102474] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Accepted: 06/09/2014] [Indexed: 12/22/2022] Open
Abstract
Interphase chromosomes in Saccharomyces cerevisiae are tethered to the nuclear envelope at their telomeres and to the spindle pole body (SPB) at their centromeres. Using a polymer model of yeast chromosomes that includes these interactions, we show theoretically that telomere attachment to the nuclear envelope is a major determinant of gene positioning within the nucleus only for genes within 10 kb of the telomeres. We test this prediction by measuring the distance between the SPB and the silent mating locus (HML) on chromosome III in wild-type and mutant yeast strains that contain altered chromosome-tethering interactions. In wild-type yeast cells we find that disruption of the telomere tether does not dramatically change the position of HML with respect to the SPB, in agreement with theoretical predictions. Alternatively, using a mutant strain with a synthetic tether that localizes an HML-proximal site to the nuclear envelope, we find a significant change in the SPB-HML distance, again as predicted by theory. Our study quantifies the importance of tethering at telomeres on the organization of interphase chromosomes in yeast, which has been shown to play a significant role in determining chromosome function such as gene expression and recombination.
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Hoang SA, Bekiranov S. The network architecture of the Saccharomyces cerevisiae genome. PLoS One 2013; 8:e81972. [PMID: 24349163 PMCID: PMC3857230 DOI: 10.1371/journal.pone.0081972] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2013] [Accepted: 10/18/2013] [Indexed: 11/19/2022] Open
Abstract
We propose a network-based approach for surmising the spatial organization of genomes from high-throughput interaction data. Our strategy is based on methods for inferring architectural features of networks. Specifically, we employ a community detection algorithm to partition networks of genomic interactions. These community partitions represent an intuitive interpretation of genomic organization from interaction data. Furthermore, they are able to recapitulate known aspects of the spatial organization of the Saccharomyces cerevisiae genome, such as the rosette conformation of the genome, the clustering of centromeres, as well as tRNAs, and telomeres. We also demonstrate that simple architectural features of genomic interaction networks, such as cliques, can give meaningful insight into the functional role of the spatial organization of the genome. We show that there is a correlation between inter-chromosomal clique size and replication timing, as well as cohesin enrichment. Together, our network-based approach represents an effective and intuitive framework for interpreting high-throughput genomic interaction data. Importantly, there is a great potential for this strategy, given the rich literature and extensive set of existing tools in the field of network analysis.
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Affiliation(s)
- Stephen A. Hoang
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, Virginia, United States of America
| | - Stefan Bekiranov
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, Virginia, United States of America
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36
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Centromere tethering confines chromosome domains. Mol Cell 2013; 52:819-31. [PMID: 24268574 DOI: 10.1016/j.molcel.2013.10.021] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2013] [Revised: 09/10/2013] [Accepted: 10/14/2013] [Indexed: 12/20/2022]
Abstract
The organization of chromosomes into territories plays an important role in a wide range of cellular processes, including gene expression, transcription, and DNA repair. Current understanding has largely excluded the spatiotemporal dynamic fluctuations of the chromatin polymer. We combine in vivo chromatin motion analysis with mathematical modeling to elucidate the physical properties that underlie the formation and fluctuations of territories. Chromosome motion varies in predicted ways along the length of the chromosome, dependent on tethering at the centromere. Detachment of a tether upon inactivation of the centromere results in increased spatial mobility. A confined bead-spring chain tethered at both ends provides a mechanism to generate observed variations in local mobility as a function of distance from the tether. These predictions are realized in experimentally determined higher effective spring constants closer to the centromere. The dynamic fluctuations and territorial organization of chromosomes are, in part, dictated by tethering at the centromere.
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37
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Hajjoul H, Mathon J, Ranchon H, Goiffon I, Mozziconacci J, Albert B, Carrivain P, Victor JM, Gadal O, Bystricky K, Bancaud A. High-throughput chromatin motion tracking in living yeast reveals the flexibility of the fiber throughout the genome. Genome Res 2013; 23:1829-38. [PMID: 24077391 PMCID: PMC3814883 DOI: 10.1101/gr.157008.113] [Citation(s) in RCA: 130] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Chromosome dynamics are recognized to be intimately linked to genomic transactions, yet the physical principles governing spatial fluctuations of chromatin are still a matter of debate. Using high-throughput single-particle tracking, we recorded the movements of nine fluorescently labeled chromosome loci located on chromosomes III, IV, XII, and XIV of Saccharomyces cerevisiae over an extended temporal range spanning more than four orders of magnitude (10(-2)-10(3) sec). Spatial fluctuations appear to be characterized by an anomalous diffusive behavior, which is homogeneous in the time domain, for all sites analyzed. We show that this response is consistent with the Rouse polymer model, and we confirm the relevance of the model with Brownian dynamics simulations and the analysis of the statistical properties of the trajectories. Moreover, the analysis of the amplitude of fluctuations by the Rouse model shows that yeast chromatin is highly flexible, its persistence length being qualitatively estimated to <30 nm. Finally, we show that the Rouse model is also relevant to analyze chromosome motion in mutant cells depleted of proteins that bind to or assemble chromatin, and suggest that it provides a consistent framework to study chromatin dynamics. We discuss the implications of our findings for yeast genome architecture and for target search mechanisms in the nucleus.
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38
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Abstract
Telomeres are obligatory chromosomal landmarks that demarcate the ends of linear chromosomes to distinguish them from broken ends and can also serve to organize the genome. In both budding and fission yeast, they cluster at the periphery of the nucleus, potentially to establish a compartment of silent chromatin. To gain insight into telomere organization in higher organisms, we investigated their distribution in interphase nuclei of Drosophila melanogaster. We focused on the syncytial blastoderm, an excellent developmental stage for live imaging due to the synchronous division of the nuclei at this time. We followed the EGFP-labeled telomeric protein HOAP in vivo and found that the 16 telomeres yield four to six foci per nucleus, indicative of clustering. Furthermore, we confirmed clustering in other somatic tissues. Importantly, we observed that HOAP signal intensity in the clusters increases in interphase, potentially due to loading of HOAP to newly replicated telomeres. To determine the rules governing clustering, we used in vivo imaging and fluorescence in situ hybridization to test several predictions. First, we inspected mutant embryos that develop as haploids and found that clustering is not mediated by associations between homologs. Second, we probed specifically for a telomere of novel sequence and found strong evidence against DNA sequence identity and homology as critical factors. Third, we ruled out predominance of intrachromosomal interactions by marking both ends of a chromosome. Based on these results, we propose that clustering is independent of sequence and is likely maintained by an as yet undetermined factor.
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Kirkland JG, Kamakaka RT. Long-range heterochromatin association is mediated by silencing and double-strand DNA break repair proteins. ACTA ACUST UNITED AC 2013; 201:809-26. [PMID: 23733345 PMCID: PMC3678155 DOI: 10.1083/jcb.201211105] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
In yeast, the localization of homologous recombination–associated proteins to heterochromatic regions of the genome is necessary for proper nuclear organization. The eukaryotic genome is highly organized in the nucleus, and this organization affects various nuclear processes. However, the molecular details of higher-order organization of chromatin remain obscure. In the present study, we show that the Saccharomyces cerevisiae silenced loci HML and HMR cluster in three-dimensional space throughout the cell cycle and independently of the telomeres. Long-range HML–HMR interactions require the homologous recombination (HR) repair pathway and phosphorylated H2A (γ-H2A). γ-H2A is constitutively present at silenced loci in unperturbed cells, its localization requires heterochromatin, and it is restricted to the silenced domain by the transfer DNA boundary element. SMC proteins and Scc2 localize to the silenced domain, and Scc2 binding requires the presence of γ-H2A. These findings illustrate a novel pathway for heterochromatin organization and suggest a role for HR repair proteins in genomic organization.
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Affiliation(s)
- Jacob G Kirkland
- Department of Molecular, Cell and Developmental Biology, University of California, Santa Cruz, Santa Cruz, CA 95064, USA
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40
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Agmon N, Liefshitz B, Zimmer C, Fabre E, Kupiec M. Effect of nuclear architecture on the efficiency of double-strand break repair. Nat Cell Biol 2013; 15:694-9. [PMID: 23644470 DOI: 10.1038/ncb2745] [Citation(s) in RCA: 94] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2013] [Accepted: 04/02/2013] [Indexed: 12/15/2022]
Abstract
The most dangerous insults to the genome's integrity are those that break both strands of the DNA. Double-strand breaks can be repaired by homologous recombination; in this conserved mechanism, a global genomic homology search finds sequences similar to those near the break, and uses them as a template for DNA synthesis and ligation. Chromosomes occupy restricted territories within the nucleus. We show that yeast genomic regions whose nuclear territories overlap recombine more efficiently than sequences located in spatially distant territories. Tethering of telomeres and centromeres reduces the efficiency of recombination between distant genomic loci, lowering the chances of non-allelic recombination. Our results challenge present models that posit an active scanning of the whole nuclear volume by the broken chromosomal end; they demonstrate that the search for homology is a limiting step in homologous recombination, and emphasize the importance of nuclear organization in genome maintenance.
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Affiliation(s)
- Neta Agmon
- Department of Molecular Microbiology and Biotechnology, Tel Aviv University, Ramat Aviv 69978, Israel
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41
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Li S, Heermann DW. Transcriptional regulatory network shapes the genome structure of Saccharomyces cerevisiae. Nucleus 2013; 4:216-28. [PMID: 23674068 DOI: 10.4161/nucl.24875] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Among cellular processes gene transcription is central. More and more evidence is mounting that transcription is tightly connected with the spatial organization of the chromosomes. Spatial proximity of genes sharing transcriptional machinery is one of the consequences of this organization. Motivated by information on the physical relationship among genes identified via chromosomal conformation capture methods, we complement the spatial organization with the idea that genes under similar transcription factor control, but possible scattered throughout the genome, might be in physically proximity to facilitate the access of their commonly used transcription factors. Unlike the transcription factory model, "interacting" genes in our "Gene Proximity Model" are not necessarily immediate physical neighbors but are in spatial proximity. Considering the stochastic nature of TF-promoter binding, this local condensation mechanism could serve as a tie to recruit co-regulated genes to guarantee the swiftness of biological reactions. We tested this idea with a simple eukaryotic organism, Saccharomyces cerevisiae. Chromosomal interaction patterns and folding behavior generated by our model re-construct those obtained from experiments. We show that the transcriptional regulatory network has a close linkage with the genome organization in budding yeast, which is fundamental and instrumental to later studies on other more complex eukaryotes.
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Affiliation(s)
- Songling Li
- Institute for Theoretical Physics, University of Heidelberg, Heidelberg, Germany
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Hozé N, Ruault M, Amoruso C, Taddei A, Holcman D. Spatial telomere organization and clustering in yeast Saccharomyces cerevisiae nucleus is generated by a random dynamics of aggregation-dissociation. Mol Biol Cell 2013; 24:1791-800, S1-10. [PMID: 23576549 PMCID: PMC3667730 DOI: 10.1091/mbc.e13-01-0031] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
The 32 telomeres of budding yeast form clusters, yet whether clusters are due to random localization or telomeric interactions is unclear. Data from live-cell imaging are compared with a biophysical model of telomere dynamics. Direct molecular interaction between telomeres is the key parameter that regulates telomere clustering. Spatial and temporal behavior of chromosomes and their regulatory proteins is a key control mechanism in genomic function. This is exemplified by the clustering of the 32 budding yeast telomeres that form foci in which silencing factors concentrate. To uncover the determinants of telomere distribution, we compare live-cell imaging with a stochastic model of telomere dynamics that we developed. We show that random encounters alone are inadequate to produce the clustering observed in vivo. In contrast, telomere dynamics observed in vivo in both haploid and diploid cells follows a process of dissociation–aggregation. We determine the time that two telomeres spend in the same cluster for the telomere distribution observed in cells expressing different levels of the silencing factor Sir3 protein, limiting for telomere clustering. We conclude that telomere clusters, their dynamics, and their nuclear distribution result from random motion, aggregation, and dissociation of telomeric regions, specifically determined by the amount of Sir3.
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Affiliation(s)
- Nathanaël Hozé
- Institute of Biology, Group of Computational Biology and Applied Mathematics, Ecole Normale Supérieure, 75005 Paris, France
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43
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Abstract
Budding yeast, like other eukaryotes, carries its genetic information on chromosomes that are sequestered from other cellular constituents by a double membrane, which forms the nucleus. An elaborate molecular machinery forms large pores that span the double membrane and regulate the traffic of macromolecules into and out of the nucleus. In multicellular eukaryotes, an intermediate filament meshwork formed of lamin proteins bridges from pore to pore and helps the nucleus reform after mitosis. Yeast, however, lacks lamins, and the nuclear envelope is not disrupted during yeast mitosis. The mitotic spindle nucleates from the nucleoplasmic face of the spindle pole body, which is embedded in the nuclear envelope. Surprisingly, the kinetochores remain attached to short microtubules throughout interphase, influencing the position of centromeres in the interphase nucleus, and telomeres are found clustered in foci at the nuclear periphery. In addition to this chromosomal organization, the yeast nucleus is functionally compartmentalized to allow efficient gene expression, repression, RNA processing, genomic replication, and repair. The formation of functional subcompartments is achieved in the nucleus without intranuclear membranes and depends instead on sequence elements, protein-protein interactions, specific anchorage sites at the nuclear envelope or at pores, and long-range contacts between specific chromosomal loci, such as telomeres. Here we review the spatial organization of the budding yeast nucleus, the proteins involved in forming nuclear subcompartments, and evidence suggesting that the spatial organization of the nucleus is important for nuclear function.
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Wong H, Marie-Nelly H, Herbert S, Carrivain P, Blanc H, Koszul R, Fabre E, Zimmer C. A predictive computational model of the dynamic 3D interphase yeast nucleus. Curr Biol 2012; 22:1881-90. [PMID: 22940469 DOI: 10.1016/j.cub.2012.07.069] [Citation(s) in RCA: 112] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2012] [Revised: 07/09/2012] [Accepted: 07/31/2012] [Indexed: 11/25/2022]
Abstract
BACKGROUND Despite the absence of internal membranes, the nucleus of eukaryotic cells is spatially organized, with chromosomes and individual loci occupying dynamic, but nonrandom, spatial positions relative to nuclear landmarks and to each other. These positional preferences correlate with gene expression and DNA repair, recombination, and replication. Yet the principles that govern nuclear organization remain poorly understood and detailed predictive models are lacking. RESULTS We present a computational model of dynamic chromosome configurations in the interphase yeast nucleus that is based on first principles and is able to statistically predict the positioning of any locus in nuclear space. Despite its simplicity, the model agrees with extensive previous and new measurements on locus positioning and with genome-wide DNA contact frequencies. Notably, our model recapitulates the position and morphology of the nucleolus, the observed variations in locus positions, and variations in contact frequencies within and across chromosomes, as well as subchromosomal contact features. The model is also able to correctly predict nuclear reorganization accompanying a reduction in ribosomal DNA transcription, and sites of chromosomal rearrangements tend to occur where the model predicted high contact frequencies. CONCLUSIONS Our results suggest that large-scale yeast nuclear architecture can be largely understood as a consequence of generic properties of crowded polymers rather than of specific DNA-binding factors and that configurations of chromosomes and DNA contacts are dictated mainly by genomic location and chromosome lengths. Our model provides a quantitative framework to understand and predict large-scale spatial genome organization and its interplay with functional processes.
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Affiliation(s)
- Hua Wong
- Institut Pasteur, Groupe Imagerie et Modélisation, 75015 Paris, France
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Londoño-Vallejo JA, Wellinger RJ. Telomeres and telomerase dance to the rhythm of the cell cycle. Trends Biochem Sci 2012; 37:391-9. [PMID: 22727244 DOI: 10.1016/j.tibs.2012.05.004] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2012] [Revised: 05/21/2012] [Accepted: 05/25/2012] [Indexed: 11/27/2022]
Abstract
The stability of the ends of linear eukaryotic chromosomes is ensured by functional telomeres, which are composed of short, species-specific direct repeat sequences. The maintenance of telomeres depends on a specialized ribonucleoprotein (RNP) called telomerase. Both telomeres and telomerase are dynamic entities with different physical behaviors and, given their substrate-enzyme relation, they must establish a productive interaction. Regulatory mechanisms controlling this interaction are key missing elements in our understanding of telomere functions. Here, we review the dynamic properties of telomeres and the maturing telomerase RNPs, and summarize how tracking the timing of their dance during the cell cycle will yield insights into chromosome stability mechanisms. Cancer cells often display loss of genome integrity; therefore, these issues are of particular interest for our understanding of cancer initiation or progression.
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Affiliation(s)
- J Arturo Londoño-Vallejo
- Laboratoire Télomères et Cancer, UMR3244, Institut Curie, 26 rue d'Ulm, 75248 Paris, France; UPMC Université Paris 06, F-75005 Paris, France
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46
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Gehlen LR, Gruenert G, Jones MB, Rodley CD, Langowski J, O'Sullivan JM. Chromosome positioning and the clustering of functionally related loci in yeast is driven by chromosomal interactions. Nucleus 2012; 3:370-83. [PMID: 22688649 DOI: 10.4161/nucl.20971] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
In recent years there has been considerable and growing interest in the 3-dimensional organization of genomes. In this manuscript we present an integrated computational-molecular study that produces an ensemble of high-resolution 3-dimensional conformations of the budding yeast genome. The compaction, folding and spatial organization of the chromosomes was based on empirical data determined using proximity-based ligation. Our models incorporate external constraints that allow the separation of gross organizational effects from those due to local interactions. Our models show that yeast chromosomes have preferred yet non-exclusive positions. They also identify interaction dependent clustering of tRNAs, early firing origins of replication, and Gal4 protein binding sites, yet the cluster composition is dynamic. Our results support a link between structure and transcription that occurs within the context of a flexible genome organization.
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Affiliation(s)
- Lutz R Gehlen
- Institute of Natural Sciences, Massey University, Auckland, New Zealand
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Tokuda N, Terada TP, Sasai M. Dynamical modeling of three-dimensional genome organization in interphase budding yeast. Biophys J 2012; 102:296-304. [PMID: 22339866 DOI: 10.1016/j.bpj.2011.12.005] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2011] [Revised: 12/04/2011] [Accepted: 12/06/2011] [Indexed: 11/17/2022] Open
Abstract
Eukaryotic genome is organized in a set of chromosomes each of which consists of a chain of DNA and associated proteins. Processes involving DNA such as transcription, duplication, and repair, therefore, should be intrinsically related to the three-dimensional organization of the genome. In this article, we develop a computational model of the three-dimensional organization of the haploid genome of interphase budding yeast by regarding chromosomes as chains moving under the constraints of nuclear structure and chromatin-chromatin interactions. The simulated genome structure largely fluctuates with the diffusive movement of chromosomes. This fluctuation, however, is not completely random, as parts of chromosomes distribute in characteristic ways to form "territories" in the nucleus. By suitably taking account of constraints arising from the data of the chromosome-conformation-capture measurement, the model explains the observed fluorescence data of chromosome distributions and motions.
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Affiliation(s)
- Naoko Tokuda
- Department of Computational Science and Engineering, Nagoya University, Nagoya, Japan
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Tjong H, Gong K, Chen L, Alber F. Physical tethering and volume exclusion determine higher-order genome organization in budding yeast. Genome Res 2012; 22:1295-305. [PMID: 22619363 PMCID: PMC3396370 DOI: 10.1101/gr.129437.111] [Citation(s) in RCA: 161] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
In this paper we show that tethering of heterochromatic regions to nuclear landmarks and random encounters of chromosomes in the confined nuclear volume are sufficient to explain the higher-order organization of the budding yeast genome. We have quantitatively characterized the contact patterns and nuclear territories that emerge when chromosomes are allowed to behave as constrained but otherwise randomly configured flexible polymer chains in the nucleus. Remarkably, this constrained random encounter model explains in a statistical manner the experimental hallmarks of the S. cerevisiae genome organization, including (1) the folding patterns of individual chromosomes; (2) the highly enriched interactions between specific chromatin regions and chromosomes; (3) the emergence, shape, and position of gene territories; (4) the mean distances between pairs of telomeres; and (5) even the co-location of functionally related gene loci, including early replication start sites and tRNA genes. Therefore, most aspects of the yeast genome organization can be explained without calling on biochemically mediated chromatin interactions. Such interactions may modulate the pre-existing propensity for co-localization but seem not to be the cause for the observed higher-order organization. The fact that geometrical constraints alone yield a highly organized genome structure, on which different functional elements are specifically distributed, has strong implications for the folding principles of the genome and the evolution of its function.
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Affiliation(s)
- Harianto Tjong
- Molecular and Computational Biology, Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, USA
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Nagai S, Heun P, Gasser SM. Roles for nuclear organization in the maintenance of genome stability. Epigenomics 2012; 2:289-305. [PMID: 22121875 DOI: 10.2217/epi.09.49] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Recent findings demonstrate that chromatin dynamics and nuclear organization are not only important for gene regulation but also for the maintenance of genome stability. Thanks to novel techniques that allow the visualization of specific chromatin domains in living cells, recent studies have demonstrated that the spatial dynamics of double-strand breaks and modifying enzymes can influence repair. The importance of the spatial organization in the repair of DNA damage has been confirmed by demonstrating that perturbation of nuclear organization can lead to gene amplifications, deletions, translocations and end-to-end telomere fusion events.
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Affiliation(s)
- Shigeki Nagai
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, Basel, Switzerland
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Abstract
Using the MS2 system for labeling mRNA, in this issue, Gallardo et al. (2011) find that telomere lengthening depends on a stable accumulation of multiple telomerase complexes in late S phase and that this process is temporally regulated by Rif1/2 proteins.
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Affiliation(s)
- S Hocine
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, NY 10461, USA
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