1
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Cook D, Kozmin SG, Yeh E, Petes TD, Bloom K. Dicentric chromosomes are resolved through breakage and repair at their centromeres. Chromosoma 2024; 133:117-134. [PMID: 38165460 PMCID: PMC11180013 DOI: 10.1007/s00412-023-00814-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2023] [Revised: 11/11/2023] [Accepted: 12/21/2023] [Indexed: 01/03/2024]
Abstract
Chromosomes with two centromeres provide a unique opportunity to study chromosome breakage and DNA repair using completely endogenous cellular machinery. Using a conditional transcriptional promoter to control the second centromere, we are able to activate the dicentric chromosome and follow the appearance of DNA repair products. We find that the rate of appearance of DNA repair products resulting from homology-based mechanisms exceeds the expected rate based on their limited centromere homology (340 bp) and distance from one another (up to 46.3 kb). In order to identify whether DNA breaks originate in the centromere, we introduced 12 single-nucleotide polymorphisms (SNPs) into one of the centromeres. Analysis of the distribution of SNPs in the recombinant centromeres reveals that recombination was initiated with about equal frequency within the conserved centromere DNA elements CDEII and CDEIII of the two centromeres. The conversion tracts range from about 50 bp to the full length of the homology between the two centromeres (340 bp). Breakage and repair events within and between the centromeres can account for the efficiency and distribution of DNA repair products. We propose that in addition to providing a site for kinetochore assembly, the centromere may be a point of stress relief in the face of genomic perturbations.
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Affiliation(s)
- Diana Cook
- Department of Biology, University of North Carolina Chapel Hill, Chapel Hill, NC, 27599-3280, USA
| | - Stanislav G Kozmin
- Department of Molecular Genetics & Microbiology, Duke University School of Medicine, Durham, NC, 27710, USA
| | - Elaine Yeh
- Department of Biology, University of North Carolina Chapel Hill, Chapel Hill, NC, 27599-3280, USA
| | - Thomas D Petes
- Department of Molecular Genetics & Microbiology, Duke University School of Medicine, Durham, NC, 27710, USA
| | - Kerry Bloom
- Department of Biology, University of North Carolina Chapel Hill, Chapel Hill, NC, 27599-3280, USA.
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2
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Ólafsson G, Haase MAB, Boeke JD. Humanization reveals pervasive incompatibility of yeast and human kinetochore components. G3 (BETHESDA, MD.) 2023; 14:jkad260. [PMID: 37962556 PMCID: PMC10755175 DOI: 10.1093/g3journal/jkad260] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2023] [Revised: 06/29/2023] [Accepted: 11/06/2023] [Indexed: 11/15/2023]
Abstract
Kinetochores assemble on centromeres to drive chromosome segregation in eukaryotic cells. Humans and budding yeast share most of the structural subunits of the kinetochore, whereas protein sequences have diverged considerably. The conserved centromeric histone H3 variant, CenH3 (CENP-A in humans and Cse4 in budding yeast), marks the site for kinetochore assembly in most species. A previous effort to complement Cse4 in yeast with human CENP-A was unsuccessful; however, co-complementation with the human core nucleosome was not attempted. Previously, our lab successfully humanized the core nucleosome in yeast; however, this severely affected cellular growth. We hypothesized that yeast Cse4 is incompatible with humanized nucleosomes and that the kinetochore represented a limiting factor for efficient histone humanization. Thus, we argued that including the human CENP-A or a Cse4-CENP-A chimera might improve histone humanization and facilitate kinetochore function in humanized yeast. The opposite was true: CENP-A expression reduced histone humanization efficiency, was toxic to yeast, and disrupted cell cycle progression and kinetochore function in wild-type (WT) cells. Suppressors of CENP-A toxicity included gene deletions of subunits of 3 conserved chromatin remodeling complexes, highlighting their role in CenH3 chromatin positioning. Finally, we attempted to complement the subunits of the NDC80 kinetochore complex, individually and in combination, without success, in contrast to a previous study indicating complementation by the human NDC80/HEC1 gene. Our results suggest that limited protein sequence similarity between yeast and human components in this very complex structure leads to failure of complementation.
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Affiliation(s)
- Guðjón Ólafsson
- Institute for Systems Genetics and Department of Biochemistry and Molecular Pharmacology, NYU Langone Health, New York, NY 10016, USA
| | - Max A B Haase
- Institute for Systems Genetics and Department of Biochemistry and Molecular Pharmacology, NYU Langone Health, New York, NY 10016, USA
- Vilcek Institute of Graduate Biomedical Sciences, NYU School of Medicine, New York, NY 10016, USA
| | - Jef D Boeke
- Institute for Systems Genetics and Department of Biochemistry and Molecular Pharmacology, NYU Langone Health, New York, NY 10016, USA
- Department of Biomedical Engineering, NYU Tandon School of Engineering, Brooklyn, NY 14 11201, USA
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3
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Lauer S, Luo J, Lazar-Stefanita L, Zhang W, McCulloch LH, Fanfani V, Lobzaev E, Haase MA, Easo N, Zhao Y, Yu F, Cai J, Bader JS, Stracquadanio G, Boeke JD. Context-dependent neocentromere activity in synthetic yeast chromosome VIII. CELL GENOMICS 2023; 3:100437. [PMID: 38020969 PMCID: PMC10667555 DOI: 10.1016/j.xgen.2023.100437] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Revised: 07/20/2023] [Accepted: 10/11/2023] [Indexed: 12/01/2023]
Abstract
Pioneering advances in genome engineering, and specifically in genome writing, have revolutionized the field of synthetic biology, propelling us toward the creation of synthetic genomes. The Sc2.0 project aims to build the first fully synthetic eukaryotic organism by assembling the genome of Saccharomyces cerevisiae. With the completion of synthetic chromosome VIII (synVIII) described here, this goal is within reach. In addition to writing the yeast genome, we sought to manipulate an essential functional element: the point centromere. By relocating the native centromere sequence to various positions along chromosome VIII, we discovered that the minimal 118-bp CEN8 sequence is insufficient for conferring chromosomal stability at ectopic locations. Expanding the transplanted sequence to include a small segment (∼500 bp) of the CDEIII-proximal pericentromere improved chromosome stability, demonstrating that minimal centromeres display context-dependent functionality.
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Affiliation(s)
- Stephanie Lauer
- Institute for Systems Genetics and Department of Biochemistry and Molecular Pharmacology, NYU Langone Health, New York, NY, USA
| | - Jingchuan Luo
- Institute for Systems Genetics and Department of Biochemistry and Molecular Pharmacology, NYU Langone Health, New York, NY, USA
| | - Luciana Lazar-Stefanita
- Institute for Systems Genetics and Department of Biochemistry and Molecular Pharmacology, NYU Langone Health, New York, NY, USA
| | - Weimin Zhang
- Institute for Systems Genetics and Department of Biochemistry and Molecular Pharmacology, NYU Langone Health, New York, NY, USA
| | - Laura H. McCulloch
- Institute for Systems Genetics and Department of Biochemistry and Molecular Pharmacology, NYU Langone Health, New York, NY, USA
| | - Viola Fanfani
- School of Biological Sciences, The University of Edinburgh, Edinburgh, UK
| | - Evgenii Lobzaev
- School of Biological Sciences, The University of Edinburgh, Edinburgh, UK
- School of Informatics, The University of Edinburgh, Edinburgh, UK
| | - Max A.B. Haase
- Institute for Systems Genetics and Department of Biochemistry and Molecular Pharmacology, NYU Langone Health, New York, NY, USA
| | - Nicole Easo
- Institute for Systems Genetics and Department of Biochemistry and Molecular Pharmacology, NYU Langone Health, New York, NY, USA
| | - Yu Zhao
- Institute for Systems Genetics and Department of Biochemistry and Molecular Pharmacology, NYU Langone Health, New York, NY, USA
| | - Fangzhou Yu
- Institute for Systems Genetics and Department of Biochemistry and Molecular Pharmacology, NYU Langone Health, New York, NY, USA
| | - Jitong Cai
- Department of Biomedical Engineering, Whiting School of Engineering, Johns Hopkins University, Baltimore, MD, USA
| | - Joel S. Bader
- Department of Biomedical Engineering, Whiting School of Engineering, Johns Hopkins University, Baltimore, MD, USA
| | | | - Jef D. Boeke
- Institute for Systems Genetics and Department of Biochemistry and Molecular Pharmacology, NYU Langone Health, New York, NY, USA
- Department of Biomedical Engineering, NYU Tandon School of Engineering, Brooklyn, NY, USA
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4
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Hill HJ, Bonser D, Golic KG. Dicentric chromosome breakage in Drosophila melanogaster is influenced by pericentric heterochromatin and occurs in nonconserved hotspots. Genetics 2023; 224:iyad052. [PMID: 37010100 PMCID: PMC10213500 DOI: 10.1093/genetics/iyad052] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Revised: 10/18/2022] [Accepted: 03/13/2023] [Indexed: 04/04/2023] Open
Abstract
Chromosome breakage plays an important role in the evolution of karyotypes and can produce deleterious effects within a single individual, such as aneuploidy or cancer. Forces that influence how and where chromosomes break are not fully understood. In humans, breakage tends to occur in conserved hotspots called common fragile sites (CFS), especially during replication stress. By following the fate of dicentric chromosomes in Drosophila melanogaster, we find that breakage under tension also tends to occur in specific hotspots. Our experimental approach was to induce sister chromatid exchange in a ring chromosome to generate a dicentric chromosome with a double chromatid bridge. In the following cell division, the dicentric bridges may break. We analyzed the breakage patterns of 3 different ring-X chromosomes. These chromosomes differ by the amount and quality of heterochromatin they carry as well as their genealogical history. For all 3 chromosomes, breakage occurs preferentially in several hotspots. Surprisingly, we found that the hotspot locations are not conserved between the 3 chromosomes: each displays a unique array of breakage hotspots. The lack of hotspot conservation, along with a lack of response to aphidicolin, suggests that these breakage sites are not entirely analogous to CFS and may reveal new mechanisms of chromosome fragility. Additionally, the frequency of dicentric breakage and the durability of each chromosome's spindle attachment vary significantly between the 3 chromosomes and are correlated with the origin of the centromere and the amount of pericentric heterochromatin. We suggest that different centromere strengths could account for this.
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Affiliation(s)
- Hunter J Hill
- School of Biological Sciences, University of Utah, Salt Lake City, UT 84112, USA
| | - Danielle Bonser
- School of Biological Sciences, University of Utah, Salt Lake City, UT 84112, USA
| | - Kent G Golic
- School of Biological Sciences, University of Utah, Salt Lake City, UT 84112, USA
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5
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Cook D, Long S, Stanton J, Cusick P, Lawrimore C, Yeh E, Grant S, Bloom K. Behavior of dicentric chromosomes in budding yeast. PLoS Genet 2021; 17:e1009442. [PMID: 33735169 PMCID: PMC8009378 DOI: 10.1371/journal.pgen.1009442] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Revised: 03/30/2021] [Accepted: 02/24/2021] [Indexed: 12/15/2022] Open
Abstract
DNA double-strand breaks arise in vivo when a dicentric chromosome (two centromeres on one chromosome) goes through mitosis with the two centromeres attached to opposite spindle pole bodies. Repair of the DSBs generates phenotypic diversity due to the range of monocentric derivative chromosomes that arise. To explore whether DSBs may be differentially repaired as a function of their spatial position in the chromosome, we have examined the structure of monocentric derivative chromosomes from cells containing a suite of dicentric chromosomes in which the distance between the two centromeres ranges from 6.5 kb to 57.7 kb. Two major classes of repair products, homology-based (homologous recombination (HR) and single-strand annealing (SSA)) and end-joining (non-homologous (NHEJ) and micro-homology mediated (MMEJ)) were identified. The distribution of repair products varies as a function of distance between the two centromeres. Genetic dependencies on double strand break repair (Rad52), DNA ligase (Lif1), and S phase checkpoint (Mrc1) are indicative of distinct repair pathway choices for DNA breaks in the pericentromeric chromatin versus the arms. A challenge in chromosome biology is to integrate the linear code with spatial organization and chromosome dynamics within the nucleus. The major sub-division of function in the nucleus is the nucleolus, the site of ribosomal RNA synthesis. We report that the pericentromere DNA surrounding the centromere is another region of confined biochemistry. We have found that chromosome breaks between two centromeres that both lie within the pericentromeric region of the chromosomes are repaired via pathways that do not rely on sequence homology (MMEJ or NHEJ). Chromosome breaks in dicentric chromosomes whose centromeres are separated by > 20 kb are repaired via pathways that rely mainly on sequence homology (HR, SSA). The repair of breaks in the pericentromere versus breaks in the arms are differentially dependent on Rad52, Lif1, and Mrc1, further indicative of spatial control over DNA repair pathways.
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Affiliation(s)
- Diana Cook
- Department of Biology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Sarah Long
- Department of Biology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - John Stanton
- Department of Biology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Patrick Cusick
- Department of Biology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Colleen Lawrimore
- Department of Biology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Elaine Yeh
- Department of Biology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Sarah Grant
- Department of Biology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Kerry Bloom
- Department of Biology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
- * E-mail:
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6
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De Novo Centromere Formation: One's Company, Two's a Crowd. Dev Cell 2020; 52:257-258. [PMID: 32049036 DOI: 10.1016/j.devcel.2020.01.021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Chromosomes containing two centromeres (dicentrics) trigger chromosome instability that is avoided by the enigmatic process of centromere inactivation. In this issue of Developmental Cell, Palladino et al. (2020) combine in vivo chromosome engineering and Drosophila genetics to assess consequences of de novo centromere formation and clarify models of centromere inactivation.
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7
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Shao Y, Lu N, Xue X, Qin Z. Creating functional chromosome fusions in yeast with CRISPR-Cas9. Nat Protoc 2019; 14:2521-2545. [PMID: 31300803 DOI: 10.1038/s41596-019-0192-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Accepted: 05/14/2019] [Indexed: 11/09/2022]
Abstract
CRISPR-Cas9-facilitated functional chromosome fusion allows the generation of a series of yeast strains with progressively reduced chromosome numbers that are valuable resources for the study of fundamental concepts in chromosome biology, including replication, recombination and segregation. We created a new yeast strain with a single chromosome by using the protocol for chromosome fusion described herein. To ensure the accuracy of chromosome fusions in yeast, the long redundant repetitive sequences near linear chromosomal ends are deleted, and the fusion orders are correspondingly determined. Possible influence on gene expression is minimized to retain gene functionality. This protocol provides experimentally derived guidelines for the generation of functional chromosome fusions in yeast, especially for the deletion of repetitive sequences, the determination of the fusion order and cleavage sites, and primary evaluation of the functionality of chromosome fusions. Beginning with design, one round of typical chromosome fusion and functional verifications can be accomplished within 18 d.
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Affiliation(s)
- Yangyang Shao
- Key Laboratory of Synthetic Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Ning Lu
- Key Laboratory of Synthetic Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Xiaoli Xue
- Key Laboratory of Synthetic Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China.
| | - Zhongjun Qin
- Key Laboratory of Synthetic Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China.
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8
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Guérin TM, Béneut C, Barinova N, López V, Lazar-Stefanita L, Deshayes A, Thierry A, Koszul R, Dubrana K, Marcand S. Condensin-Mediated Chromosome Folding and Internal Telomeres Drive Dicentric Severing by Cytokinesis. Mol Cell 2019; 75:131-144.e3. [PMID: 31204167 DOI: 10.1016/j.molcel.2019.05.021] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Revised: 02/12/2019] [Accepted: 05/13/2019] [Indexed: 12/13/2022]
Abstract
In Saccharomyces cerevisiae, dicentric chromosomes stemming from telomere fusions preferentially break at the fusion. This process restores a normal karyotype and protects chromosomes from the detrimental consequences of accidental fusions. Here, we address the molecular basis of this rescue pathway. We observe that tandem arrays tightly bound by the telomere factor Rap1 or a heterologous high-affinity DNA binding factor are sufficient to establish breakage hotspots, mimicking telomere fusions within dicentrics. We also show that condensins generate forces sufficient to rapidly refold dicentrics prior to breakage by cytokinesis and are essential to the preferential breakage at telomere fusions. Thus, the rescue of fused telomeres results from a condensin- and Rap1-driven chromosome folding that favors fusion entrapment where abscission takes place. Because a close spacing between the DNA-bound Rap1 molecules is essential to this process, Rap1 may act by stalling condensins.
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Affiliation(s)
- Thomas M Guérin
- CEA Paris-Saclay, Unité Stabilité Génétique Cellules Souches et Radiations, INSERM U1274, Université de Paris, Université Paris-Saclay, Fontenay-aux-roses, France
| | - Claire Béneut
- CEA Paris-Saclay, Unité Stabilité Génétique Cellules Souches et Radiations, INSERM U1274, Université de Paris, Université Paris-Saclay, Fontenay-aux-roses, France
| | - Natalja Barinova
- CEA Paris-Saclay, Unité Stabilité Génétique Cellules Souches et Radiations, INSERM U1274, Université de Paris, Université Paris-Saclay, Fontenay-aux-roses, France
| | - Virginia López
- CEA Paris-Saclay, Unité Stabilité Génétique Cellules Souches et Radiations, INSERM U1274, Université de Paris, Université Paris-Saclay, Fontenay-aux-roses, France
| | - Luciana Lazar-Stefanita
- Institut Pasteur, Unité Régulation Spatiale des Génomes, CNRS UMR 3525, Sorbonne Université, Paris, France
| | - Alice Deshayes
- CEA Paris-Saclay, Unité Stabilité Génétique Cellules Souches et Radiations, INSERM U1274, Université de Paris, Université Paris-Saclay, Fontenay-aux-roses, France
| | - Agnès Thierry
- Institut Pasteur, Unité Régulation Spatiale des Génomes, CNRS UMR 3525, Sorbonne Université, Paris, France
| | - Romain Koszul
- Institut Pasteur, Unité Régulation Spatiale des Génomes, CNRS UMR 3525, Sorbonne Université, Paris, France
| | - Karine Dubrana
- CEA Paris-Saclay, Unité Stabilité Génétique Cellules Souches et Radiations, INSERM U1274, Université de Paris, Université Paris-Saclay, Fontenay-aux-roses, France
| | - Stéphane Marcand
- CEA Paris-Saclay, Unité Stabilité Génétique Cellules Souches et Radiations, INSERM U1274, Université de Paris, Université Paris-Saclay, Fontenay-aux-roses, France.
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9
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Hou H, Cooper JP. Stretching, scrambling, piercing and entangling: Challenges for telomeres in mitotic and meiotic chromosome segregation. Differentiation 2018; 100:12-20. [PMID: 29413748 DOI: 10.1016/j.diff.2018.01.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2017] [Revised: 01/21/2018] [Accepted: 01/23/2018] [Indexed: 12/24/2022]
Abstract
The consequences of telomere loss or dysfunction become most prominent when cells enter the nuclear division stage of the cell cycle. At this climactic stage when chromosome segregation occurs, telomere fusions or entanglements can lead to chromosome breakage, wreaking havoc on genome stability. Here we review recent progress in understanding the mechanisms of detangling and breaking telomere associations at mitosis, as well as the unique ways in which telomeres are processed to allow regulated sister telomere separation. Moreover, we discuss unexpected roles for telomeres in orchestrating nuclear envelope breakdown and spindle formation, crucial processes for nuclear division. Finally, we discuss the discovery that telomeres create microdomains in the nucleus that are conducive to centromere assembly, cementing the unexpectedly influential role of telomeres in mitosis.
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Affiliation(s)
- Haitong Hou
- Telomere Biology Section, LBMB, NCI, NIH, Building 37, Room 6050, Bethesda MD 20892, USA
| | - Julia Promisel Cooper
- Telomere Biology Section, LBMB, NCI, NIH, Building 37, Room 6050, Bethesda MD 20892, USA.
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10
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Ólafsson G, Thorpe PH. Rewiring the Budding Yeast Proteome using Synthetic Physical Interactions. Methods Mol Biol 2018; 1672:599-612. [PMID: 29043650 DOI: 10.1007/978-1-4939-7306-4_39] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
Artificially tethering two proteins or protein fragments together is a powerful method to query molecular mechanisms. However, this approach typically relies upon a prior understanding of which two proteins, when fused, are most likely to provide a specific function and is therefore not readily amenable to large-scale screening. Here, we describe the Synthetic Physical Interaction (SPI) method to create proteome-wide forced protein associations in the budding yeast Saccharomyces cerevisiae. This method allows thousands of protein-protein associations to be screened for those that affect either normal growth or sensitivity to drugs or specific conditions. The method is amenable to proteins, protein domains, or any genetically encoded peptide sequence.
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Affiliation(s)
- Guðjón Ólafsson
- Mitotic Control Laboratory, The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK
| | - Peter H Thorpe
- Mitotic Control Laboratory, The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK.
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11
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Position effects influencing intrachromosomal repair of a double-strand break in budding yeast. PLoS One 2017; 12:e0180994. [PMID: 28700723 PMCID: PMC5507452 DOI: 10.1371/journal.pone.0180994] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2017] [Accepted: 06/23/2017] [Indexed: 12/23/2022] Open
Abstract
Repair of a double-strand break (DSB) by an ectopic homologous donor sequence is subject to the three-dimensional arrangement of chromosomes in the nucleus of haploid budding yeast. The data for interchromosomal recombination suggest that searching for homology is accomplished by a random collision process, strongly influenced by the contact probability of the donor and recipient sequences. Here we explore how recombination occurs on the same chromosome and whether there are additional constraints imposed on repair. Specifically, we examined how intrachromosomal repair is affected by the location of the donor sequence along the 813-kb chromosome 2 (Chr2), with a site-specific DSB created on the right arm (position 625 kb). Repair correlates well with contact frequencies determined by chromosome conformation capture-based studies (r = 0.85). Moreover, there is a profound constraint imposed by the anchoring of the centromere (CEN2, position 238 kb) to the spindle pole body. Sequences at the same distance on either side of CEN2 are equivalently constrained in recombining with a DSB located more distally on one arm, suggesting that sequences on the opposite arm from the DSB are not otherwise constrained in their interaction with the DSB. The centromere constraint can be partially relieved by inducing transcription through the centromere to inactivate CEN2 tethering. In diploid cells, repair of a DSB via its allelic donor is strongly influenced by the presence and the position of an ectopic intrachromosomal donor.
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12
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Barrey EJ, Heun P. Artificial Chromosomes and Strategies to Initiate Epigenetic Centromere Establishment. PROGRESS IN MOLECULAR AND SUBCELLULAR BIOLOGY 2017; 56:193-212. [PMID: 28840238 DOI: 10.1007/978-3-319-58592-5_8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
In recent years, various synthetic approaches have been developed to address the question of what directs centromere establishment and maintenance. In this chapter, we will discuss how approaches aimed at constructing synthetic centromeres have co-evolved with and contributed to shape the theory describing the determinants of centromere identity. We will first review lessons learned from artificial chromosomes created from "naked" centromeric sequences to investigate the role of the underlying DNA for centromere formation. We will then discuss how several studies, which applied removal of endogenous centromeres or over-expression of the centromere-specific histone CENP-A, helped to investigate the contribution of chromatin context to centromere establishment. Finally, we will examine various biosynthetic approaches taking advantage of targeting specific proteins to ectopic sites in the genome to dissect the role of many centromere-associated proteins and chromatin modifiers for centromere inheritance and function. Together, these studies showed that chromatin context matters, particularly proximity to heterochromatin or repetitive DNA sequences. Moreover, despite the important contribution of centromeric DNA, the centromere-specific histone H3-variant CENP-A emerges as a key epigenetic mark to establish and maintain functional centromeres on artificial chromosomes or at ectopic sites of the genome.
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Affiliation(s)
- Evelyne J Barrey
- Wellcome Trust Centre for Cell Biology, The University of Edinburgh, Edinburgh, UK
| | - Patrick Heun
- Wellcome Trust Centre for Cell Biology, The University of Edinburgh, Edinburgh, UK.
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13
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McNulty SM, Sullivan BA. Centromere Silencing Mechanisms. PROGRESS IN MOLECULAR AND SUBCELLULAR BIOLOGY 2017; 56:233-255. [PMID: 28840240 DOI: 10.1007/978-3-319-58592-5_10] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Centromere function is essential for genome stability and chromosome inheritance. Typically, each chromosome has a single locus that consistently serves as the site of centromere formation and kinetochore assembly. Decades of research have defined the DNA sequence and protein components of functional centromeres, and the interdependencies of specific protein complexes for proper centromere assembly. Less is known about how centromeres are disassembled or functionally silenced. Centromere silencing, or inactivation, is particularly relevant in the cases of dicentric chromosomes that occur via genome rearrangements that place two centromeres on the same chromosome. Dicentrics are usually unstable unless one centromere is inactivated, thereby allowing the structurally dicentric chromosome to behave like one of the monocentric, endogenous chromosomes. The molecular basis for centromere inactivation is not well understood, although studies in model organisms and in humans suggest that both genomic and epigenetic mechanisms are involved. In this chapter, we review recent studies using synthetic chromosomes and engineered or induced dicentrics from various organisms to define the molecular processes that are involved in the complex process of centromere inactivation.
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Affiliation(s)
- Shannon M McNulty
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, DUMC 3054, Durham, NC, 27710, USA.,Division of Human Genetics, Duke University Medical Center, DUMC 3054, Durham, NC, 27710, USA
| | - Beth A Sullivan
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, DUMC 3054, Durham, NC, 27710, USA. .,Division of Human Genetics, Duke University Medical Center, DUMC 3054, Durham, NC, 27710, USA.
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14
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Beyer T, Weinert T. Ontogeny of Unstable Chromosomes Generated by Telomere Error in Budding Yeast. PLoS Genet 2016; 12:e1006345. [PMID: 27716774 PMCID: PMC5065131 DOI: 10.1371/journal.pgen.1006345] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Accepted: 09/07/2016] [Indexed: 11/19/2022] Open
Abstract
DNA replication errors at certain sites in the genome initiate chromosome instability that ultimately leads to stable genomic rearrangements. Where instability begins is often unclear. And, early instability may form unstable chromosome intermediates whose transient nature also hinders mechanistic understanding. We report here a budding yeast model that reveals the genetic ontogeny of genome rearrangements, from initial replication error to unstable chromosome formation to their resolution. Remarkably, the initial error often arises in or near the telomere, and frequently forms unstable chromosomes. Early unstable chromosomes may then resolve to an internal "collection site" where a dicentric forms and resolves to an isochromosome (other outcomes are possible at each step). The initial telomere-proximal unstable chromosome is increased in mutants in telomerase subunits, Tel1, and even Rad9, with no known telomere-specific function. Defects in Tel1 and in Rrm3, a checkpoint protein kinase with a role in telomere maintenance and a DNA helicase, respectively, synergize dramatically to generate unstable chromosomes, further illustrating the consequence of replication error in the telomere. Collectively, our results suggest telomeric replication errors may be a common cause of seemingly unrelated genomic rearrangements located hundreds of kilobases away.
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Affiliation(s)
- Tracey Beyer
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, Arizona, United States of America
| | - Ted Weinert
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, Arizona, United States of America
- * E-mail:
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15
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Ishchuk OP, Vojvoda Zeljko T, Schifferdecker AJ, Mebrahtu Wisén S, Hagström ÅK, Rozpędowska E, Rørdam Andersen M, Hellborg L, Ling Z, Sibirny AA, Piškur J. Novel Centromeric Loci of the Wine and Beer Yeast Dekkera bruxellensis CEN1 and CEN2. PLoS One 2016; 11:e0161741. [PMID: 27560164 PMCID: PMC4999066 DOI: 10.1371/journal.pone.0161741] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2016] [Accepted: 08/10/2016] [Indexed: 11/19/2022] Open
Abstract
The wine and beer yeast Dekkera bruxellensis thrives in environments that are harsh and limiting, especially in concentrations with low oxygen and high ethanol. Its different strains’ chromosomes greatly vary in number (karyotype). This study isolates two novel centromeric loci (CEN1 and CEN2), which support both the yeast’s autonomous replication and the stable maintenance of plasmids. In the sequenced genome of the D. bruxellensis strain CBS 2499, CEN1 and CEN2 are each present in one copy. They differ from the known “point” CEN elements, and their biological activity is retained within ~900–1300 bp DNA segments. CEN1 and CEN2 have features of both “point” and “regional” centromeres: They contain conserved DNA elements, ARSs, short repeats, one tRNA gene, and transposon-like elements within less than 1 kb. Our discovery of a miniature inverted-repeat transposable element (MITE) next to CEN2 is the first report of such transposons in yeast. The transformants carrying circular plasmids with cloned CEN1 and CEN2 undergo a phenotypic switch: They form fluffy colonies and produce three times more biofilm. The introduction of extra copies of CEN1 and CEN2 promotes both genome rearrangements and ploidy shifts, with these effects mediated by homologous recombination (between circular plasmid and genome centromere copy) or by chromosome breakage when integrated. Also, the proximity of the MITE-like transposon to CEN2 could translocate CEN2 within the genome or cause chromosomal breaks, so promoting genome dynamics. With extra copies of CEN1 and CEN2, the yeast’s enhanced capacities to rearrange its genome and to change its gene expression could increase its abilities for exploiting new and demanding niches.
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Affiliation(s)
- Olena P. Ishchuk
- Department of Biology, Lund University, Lund, Sweden
- Department of Molecular Genetics and Biotechnology, Institute of Cell Biology, NAS of Ukraine, Lviv, Ukraine
- * E-mail:
| | - Tanja Vojvoda Zeljko
- Department of Biology, Lund University, Lund, Sweden
- Division of Molecular Biology, Ruđer Bošković Institute, Zagreb, Croatia
| | | | | | | | | | | | | | - Zhihao Ling
- Department of Biology, Lund University, Lund, Sweden
| | - Andrei A. Sibirny
- Department of Molecular Genetics and Biotechnology, Institute of Cell Biology, NAS of Ukraine, Lviv, Ukraine
- Department of Biotechnology and Microbiology, University of Rzeszow, Rzeszow, Poland
| | - Jure Piškur
- Department of Biology, Lund University, Lund, Sweden
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16
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Maciejowski J, Li Y, Bosco N, Campbell PJ, de Lange T. Chromothripsis and Kataegis Induced by Telomere Crisis. Cell 2016; 163:1641-54. [PMID: 26687355 DOI: 10.1016/j.cell.2015.11.054] [Citation(s) in RCA: 444] [Impact Index Per Article: 55.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2015] [Revised: 11/03/2015] [Accepted: 11/20/2015] [Indexed: 11/16/2022]
Abstract
Telomere crisis occurs during tumorigenesis when depletion of the telomere reserve leads to frequent telomere fusions. The resulting dicentric chromosomes have been proposed to drive genome instability. Here, we examine the fate of dicentric human chromosomes in telomere crisis. We observed that dicentric chromosomes invariably persisted through mitosis and developed into 50-200 μm chromatin bridges connecting the daughter cells. Before their resolution at 3-20 hr after anaphase, the chromatin bridges induced nuclear envelope rupture in interphase, accumulated the cytoplasmic 3' nuclease TREX1, and developed RPA-coated single stranded (ss) DNA. CRISPR knockouts showed that TREX1 contributed to the generation of the ssDNA and the resolution of the chromatin bridges. Post-crisis clones showed chromothripsis and kataegis, presumably resulting from DNA repair and APOBEC editing of the fragmented chromatin bridge DNA. We propose that chromothripsis in human cancer may arise through TREX1-mediated fragmentation of dicentric chromosomes formed in telomere crisis.
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Affiliation(s)
- John Maciejowski
- Laboratory for Cell Biology and Genetics, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA
| | - Yilong Li
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton Cambridge, CB10 1SA, UK
| | - Nazario Bosco
- Laboratory for Cell Biology and Genetics, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA
| | - Peter J Campbell
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton Cambridge, CB10 1SA, UK.
| | - Titia de Lange
- Laboratory for Cell Biology and Genetics, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA.
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17
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Tsabar M, Haase J, Harrison B, Snider CE, Eldridge B, Kaminsky L, Hine RM, Haber JE, Bloom K. A Cohesin-Based Partitioning Mechanism Revealed upon Transcriptional Inactivation of Centromere. PLoS Genet 2016; 12:e1006021. [PMID: 27128635 PMCID: PMC4851351 DOI: 10.1371/journal.pgen.1006021] [Citation(s) in RCA: 7] [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: 09/22/2015] [Accepted: 04/08/2016] [Indexed: 12/24/2022] Open
Abstract
Transcriptional inactivation of the budding yeast centromere has been a widely used tool in studies of chromosome segregation and aneuploidy. In haploid cells when an essential chromosome contains a single conditionally inactivated centromere (GAL-CEN), cell growth rate is slowed and segregation fidelity is reduced; but colony formation is nearly 100%. Pedigree analysis revealed that only 30% of the time both mother and daughter cell inherit the GAL-CEN chromosome. The reduced segregation capacity of the GAL-CEN chromosome is further compromised upon reduction of pericentric cohesin (mcm21∆), as reflected in a further diminishment of the Mif2 kinetochore protein at GAL-CEN. By redistributing cohesin from the nucleolus to the pericentromere (by deleting SIR2), there is increased presence of the kinetochore protein Mif2 at GAL-CEN and restoration of cell viability. These studies identify the ability of cohesin to promote chromosome segregation via kinetochore assembly, in a situation where the centromere has been severely compromised.
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Affiliation(s)
- Michael Tsabar
- Department of Biology and Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, Massachusetts, United States of America
| | - Julian Haase
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Benjamin Harrison
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Chloe E. Snider
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Brittany Eldridge
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Lila Kaminsky
- Department of Biology and Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, Massachusetts, United States of America
| | - Rebecca M. Hine
- Department of Biology and Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, Massachusetts, United States of America
| | - James E. Haber
- Department of Biology and Rosenstiel Basic Medical Sciences Research Center, Brandeis University, Waltham, Massachusetts, United States of America
| | - Kerry Bloom
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
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18
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Lhuillier-Akakpo M, Guérin F, Frapporti A, Duharcourt S. DNA deletion as a mechanism for developmentally programmed centromere loss. Nucleic Acids Res 2015; 44:1553-65. [PMID: 26503246 PMCID: PMC4770206 DOI: 10.1093/nar/gkv1110] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Accepted: 10/12/2015] [Indexed: 12/31/2022] Open
Abstract
A hallmark of active centromeres is the presence of the histone H3 variant CenH3 in the centromeric chromatin, which ensures faithful genome distribution at each cell division. A functional centromere can be inactivated, but the molecular mechanisms underlying the process of centromere inactivation remain largely unknown. Here, we describe the loss of CenH3 protein as part of a developmental program leading to the formation of the somatic nucleus in the eukaryote Paramecium. We identify two proteins whose depletion prevents developmental loss of CenH3: the domesticated transposase Pgm involved in the formation of DNA double strand cleavages and the Polycomb-like lysine methyltransferase Ezl1 necessary for trimethylation of histone H3 on lysine 9 and lysine 27. Taken together, our data support a model in which developmentally programmed centromere loss is caused by the elimination of DNA sequences associated with CenH3.
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Affiliation(s)
- Maoussi Lhuillier-Akakpo
- Institut Jacques Monod, CNRS, UMR 7592, Université Paris Diderot, Sorbonne Paris Cité, Paris, F-75205 France
| | - Frédéric Guérin
- Institut Jacques Monod, CNRS, UMR 7592, Université Paris Diderot, Sorbonne Paris Cité, Paris, F-75205 France
| | - Andrea Frapporti
- Institut Jacques Monod, CNRS, UMR 7592, Université Paris Diderot, Sorbonne Paris Cité, Paris, F-75205 France
| | - Sandra Duharcourt
- Institut Jacques Monod, CNRS, UMR 7592, Université Paris Diderot, Sorbonne Paris Cité, Paris, F-75205 France
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19
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Re-replication of a centromere induces chromosomal instability and aneuploidy. PLoS Genet 2015; 11:e1005039. [PMID: 25901968 PMCID: PMC4406714 DOI: 10.1371/journal.pgen.1005039] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Accepted: 01/28/2015] [Indexed: 12/19/2022] Open
Abstract
The faithful inheritance of chromosomes during cell division requires their precise replication and segregation. Numerous mechanisms ensure that each of these fundamental cell cycle events is performed with a high degree of fidelity. The fidelity of chromosomal replication is maintained in part by re-replication controls that ensure there are no more than two copies of every genomic segment to distribute to the two daughter cells. This control is enforced by inhibiting replication initiation proteins from reinitiating replication origins within a single cell cycle. Here we show in Saccharomyces cerevisiae that re-replication control is important for the fidelity of chromosome segregation. In particular, we demonstrate that transient re-replication of centromeric DNA due to disruption of re-replication control greatly induces aneuploidy of the re-replicated chromosome. Some of this aneuploidy arises from missegregation of both sister chromatids to one daughter cell. Aneuploidy can also arise from the generation of an extra sister chromatid via homologous recombination, suggesting that centromeric re-replication can trigger breakage and repair events that expand chromosome number without causing chromosomal rearrangements. Thus, we have identified a potential new non-mitotic source of aneuploidy that can arise from a defect in re-replication control. Given the emerging connections between the deregulation of replication initiation proteins and oncogenesis, this finding may be relevant to the aneuploidy that is prevalent in cancer. The stable inheritance of genetic information requires an elaborate mitotic machinery that acts on the centromeres of chromosomes to ensure their precise segregation. Errors in this segregation can lead to aneuploidy, an unbalanced chromosomal state in which some chromosomes have different copy number than others. Because aneuploidy is associated with developmental abnormalities and diseases such as cancer, there is considerable interest in understanding how these segregation errors arise. Much of this interest has focused on identifying defects in proteins that make up the mitotic machinery. Here, we show that defects in a completely separate process, the control of DNA replication initiation, can lead to chromosome segregation errors as a result of inappropriate re-replication of centromeres. Similar deregulation of replication initiation proteins has been observed in primary human tumors and shown to promote oncogenesis in mouse models. Together, these results raise the possibility that centromeric re-replication may be an additional source of aneuploidy in cancer. In combination with our previous work showing that re-replication is a potent inducer of gene amplification, these results also highlight the versatility of re-replication as a source of genomic instability.
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20
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Abstract
Centromeres are specialized domains of heterochromatin that provide the foundation for the kinetochore. Centromeric heterochromatin is characterized by specific histone modifications, a centromere-specific histone H3 variant (CENP-A), and the enrichment of cohesin, condensin, and topoisomerase II. Centromere DNA varies orders of magnitude in size from 125 bp (budding yeast) to several megabases (human). In metaphase, sister kinetochores on the surface of replicated chromosomes face away from each other, where they establish microtubule attachment and bi-orientation. Despite the disparity in centromere size, the distance between separated sister kinetochores is remarkably conserved (approximately 1 μm) throughout phylogeny. The centromere functions as a molecular spring that resists microtubule-based extensional forces in mitosis. This review explores the physical properties of DNA in order to understand how the molecular spring is built and how it contributes to the fidelity of chromosome segregation.
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Affiliation(s)
- Kerry S Bloom
- Department of Biology, University of North Carolina, Chapel Hill, North Carolina 27599-3280;
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21
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The 19S proteasome subunit Rpt3 regulates distribution of CENP-A by associating with centromeric chromatin. Nat Commun 2014; 5:3597. [PMID: 24710126 DOI: 10.1038/ncomms4597] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2013] [Accepted: 03/10/2014] [Indexed: 12/24/2022] Open
Abstract
CENP-A, a variant of histone H3, is incorporated into centromeric chromatin and plays a role during kinetochore establishment. In fission yeast, the localization of CENP-A is limited to a region spanning 10-20 kb of the core domain of the centromere. Here, we report a mutant (rpt3-1) in which this region is expanded to 40-70 kb. Likely due to abnormal distribution of CENP-A, this mutant exhibits chromosome instability and enhanced gene silencing. Interestingly, the rpt3(+) gene encodes a subunit of the 19S proteasome, which localizes to the nuclear membrane. Although Rpt3 associates with centromeric chromatin, the mutant protein has lost this localization. A loss of the cut8(+) gene encoding an anchor of the proteasome to the nuclear membrane causes similar phenotypes as observed in the rpt3-1 mutant. Thus, we propose that the proteasome (or its subcomplex) associates with centromeric chromatin and regulates distribution of CENP-A.
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22
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Switching the centromeres on and off: epigenetic chromatin alterations provide plasticity in centromere activity stabilizing aberrant dicentric chromosomes. Biochem Soc Trans 2013; 41:1648-53. [DOI: 10.1042/bst20130136] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The kinetochore, which forms on a specific chromosomal locus called the centromere, mediates interactions between the chromosome and the spindle during mitosis and meiosis. Abnormal chromosome rearrangements and/or neocentromere formation can cause the presence of multiple centromeres on a single chromosome, which results in chromosome breakage or cell cycle arrest. Analyses of artificial dicentric chromosomes suggested that the activity of the centromere is regulated epigenetically; on some stably maintained dicentric chromosomes, one of the centromeres no longer functions as a platform for kinetochore formation, although the DNA sequence remains intact. Such epigenetic centromere inactivation occurs in cells of various eukaryotes harbouring ‘regional centromeres’, such as those of maize, fission yeast and humans, suggesting that the position of the active centromere is determined by epigenetic markers on a chromosome rather than the nucleotide sequence. Our recent findings in fission yeast revealed that epigenetic centromere inactivation consists of two steps: disassembly of the kinetochore initiates inactivation and subsequent heterochromatinization prevents revival of the inactivated centromere. Kinetochore disassembly followed by heterochromatinization is also observed in normal senescent human cells. Thus epigenetic centromere inactivation may not only stabilize abnormally generated dicentric chromosomes, but also be part of an intrinsic mechanism regulating cell proliferation.
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23
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Tanaka TU, Clayton L, Natsume T. Three wise centromere functions: see no error, hear no break, speak no delay. EMBO Rep 2013; 14:1073-83. [PMID: 24232185 PMCID: PMC3849490 DOI: 10.1038/embor.2013.181] [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] [Received: 09/05/2013] [Accepted: 10/18/2013] [Indexed: 12/17/2022] Open
Abstract
The main function of the centromere is to promote kinetochore assembly for spindle microtubule attachment. Two additional functions of the centromere, however, are becoming increasingly clear: facilitation of robust sister-chromatid cohesion at pericentromeres and advancement of replication of centromeric regions. The combination of these three centromere functions ensures correct chromosome segregation during mitosis. Here, we review the mechanisms of the kinetochore-microtubule interaction, focusing on sister-kinetochore bi-orientation (or chromosome bi-orientation). We also discuss the biological importance of robust pericentromeric cohesion and early centromere replication, as well as the mechanisms orchestrating these two functions at the microtubule attachment site.
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Affiliation(s)
- Tomoyuki U Tanaka
- Centre for Gene Regulation and Expression, College of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, UK
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24
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Natsume T, Müller C, Katou Y, Retkute R, Gierliński M, Araki H, Blow J, Shirahige K, Nieduszynski C, Tanaka T. Kinetochores coordinate pericentromeric cohesion and early DNA replication by Cdc7-Dbf4 kinase recruitment. Mol Cell 2013; 50:661-74. [PMID: 23746350 PMCID: PMC3679449 DOI: 10.1016/j.molcel.2013.05.011] [Citation(s) in RCA: 123] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2012] [Revised: 03/26/2013] [Accepted: 05/02/2013] [Indexed: 11/29/2022]
Abstract
Centromeres play several important roles in ensuring proper chromosome segregation. Not only do they promote kinetochore assembly for microtubule attachment, but they also support robust sister chromatid cohesion at pericentromeres and facilitate replication of centromeric DNA early in S phase. However, it is still elusive how centromeres orchestrate all these functions at the same site. Here, we show that the budding yeast Dbf4-dependent kinase (DDK) accumulates at kinetochores in telophase, facilitated by the Ctf19 kinetochore complex. This promptly recruits Sld3-Sld7 replication initiator proteins to pericentromeric replication origins so that they initiate replication early in S phase. Furthermore, DDK at kinetochores independently recruits the Scc2-Scc4 cohesin loader to centromeres in G1 phase. This enhances cohesin loading and facilitates robust pericentromeric cohesion in S phase. Thus, we have found the central mechanism by which kinetochores orchestrate early S phase DNA replication and robust sister chromatid cohesion at microtubule attachment sites.
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Affiliation(s)
- Toyoaki Natsume
- Centre for Gene Regulation and Expression, College of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Carolin A. Müller
- Centre for Genetics and Genomics, School of Biology, University of Nottingham, Nottingham NG7 2UH, UK
| | - Yuki Katou
- Institute of Molecular and Cellular Biosciences, University of Tokyo, Tokyo 113-0032, Japan
| | - Renata Retkute
- Centre for Genetics and Genomics, School of Biology, University of Nottingham, Nottingham NG7 2UH, UK
| | - Marek Gierliński
- Centre for Gene Regulation and Expression, College of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
- Data Analysis Group, College of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Hiroyuki Araki
- Division of Microbial Genetics, National Institute of Genetics, Mishima 411-8540, Japan
- Department of Genetics, School of Life Science, SOKENDAI, Mishima 411-8540, Japan
| | - J. Julian Blow
- Centre for Gene Regulation and Expression, College of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
| | - Katsuhiko Shirahige
- Institute of Molecular and Cellular Biosciences, University of Tokyo, Tokyo 113-0032, Japan
| | - Conrad A. Nieduszynski
- Centre for Genetics and Genomics, School of Biology, University of Nottingham, Nottingham NG7 2UH, UK
| | - Tomoyuki U. Tanaka
- Centre for Gene Regulation and Expression, College of Life Sciences, University of Dundee, Dundee DD1 5EH, UK
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25
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Stimpson KM, Matheny JE, Sullivan BA. Dicentric chromosomes: unique models to study centromere function and inactivation. Chromosome Res 2012; 20:595-605. [PMID: 22801777 DOI: 10.1007/s10577-012-9302-3] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Dicentric chromosomes are products of genome rearrangement that place two centromeres on the same chromosome. Depending on the organism, dicentric stability varies after formation. In humans, dicentrics occur naturally in a substantial portion of the population and usually segregate successfully in mitosis and meiosis. Their stability has been attributed to inactivation of one of the two centromeres, creating a functionally monocentric chromosome that can segregate normally during cell division. The molecular basis for centromere inactivation is not well understood, although studies in model organisms and in humans suggest that genomic and epigenetic mechanisms can be involved. Furthermore, constitutional dicentric chromosomes ascertained in patients presumably represent the most stable chromosomes, so the spectrum of dicentric fates, if it exists, is not entirely clear. Studies of engineered or induced dicentrics in budding yeast and plants have provided significant insight into the fate of dicentric chromosomes. And, more recently, studies have shown that dicentrics in humans can also undergo multiple fates after formation. Here, we discuss current experimental evidence from various organisms that has deepened our understanding of dicentric behavior and the intriguingly complex process of centromere inactivation.
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Affiliation(s)
- Kaitlin M Stimpson
- Institute for Genome Sciences and Policy, Duke University, Durham, NC 27708, USA
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26
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Quevedo O, García-Luis J, Matos-Perdomo E, Aragón L, Machín F. Nondisjunction of a single chromosome leads to breakage and activation of DNA damage checkpoint in G2. PLoS Genet 2012; 8:e1002509. [PMID: 22363215 PMCID: PMC3280967 DOI: 10.1371/journal.pgen.1002509] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2011] [Accepted: 12/08/2011] [Indexed: 11/18/2022] Open
Abstract
The resolution of chromosomes during anaphase is a key step in mitosis. Failure to disjoin chromatids compromises the fidelity of chromosome inheritance and generates aneuploidy and chromosome rearrangements, conditions linked to cancer development. Inactivation of topoisomerase II, condensin, or separase leads to gross chromosome nondisjunction. However, the fate of cells when one or a few chromosomes fail to separate has not been determined. Here, we describe a genetic system to induce mitotic progression in the presence of nondisjunction in yeast chromosome XII right arm (cXIIr), which allows the characterisation of the cellular fate of the progeny. Surprisingly, we find that the execution of karyokinesis and cytokinesis is timely and produces severing of cXIIr on or near the repetitive ribosomal gene array. Consequently, one end of the broken chromatid finishes up in each of the new daughter cells, generating a novel type of one-ended double-strand break. Importantly, both daughter cells enter a new cycle and the damage is not detected until the next G2, when cells arrest in a Rad9-dependent manner. Cytologically, we observed the accumulation of damage foci containing RPA/Rad52 proteins but failed to detect Mre11, indicating that cells attempt to repair both chromosome arms through a MRX-independent recombinational pathway. Finally, we analysed several surviving colonies arising after just one cell cycle with cXIIr nondisjunction. We found that aberrant forms of the chromosome were recovered, especially when RAD52 was deleted. Our results demonstrate that, in yeast cells, the Rad9-DNA damage checkpoint plays an important role responding to compromised genome integrity caused by mitotic nondisjunction.
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Affiliation(s)
- Oliver Quevedo
- Unidad de Investigación, Hospital Universitario Nuestra Señora de Candelaria, Santa Cruz de Tenerife, Spain
| | - Jonay García-Luis
- Unidad de Investigación, Hospital Universitario Nuestra Señora de Candelaria, Santa Cruz de Tenerife, Spain
| | - Emiliano Matos-Perdomo
- Unidad de Investigación, Hospital Universitario Nuestra Señora de Candelaria, Santa Cruz de Tenerife, Spain
| | - Luis Aragón
- Cell Cycle Group, MRC Clinical Sciences Centre, Imperial College London, London, United Kingdom
| | - Félix Machín
- Unidad de Investigación, Hospital Universitario Nuestra Señora de Candelaria, Santa Cruz de Tenerife, Spain
- * E-mail:
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27
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Stimpson KM, Song IY, Jauch A, Holtgreve-Grez H, Hayden KE, Bridger JM, Sullivan BA. Telomere disruption results in non-random formation of de novo dicentric chromosomes involving acrocentric human chromosomes. PLoS Genet 2010; 6. [PMID: 20711355 PMCID: PMC2920838 DOI: 10.1371/journal.pgen.1001061] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2010] [Accepted: 07/12/2010] [Indexed: 01/05/2023] Open
Abstract
Genome rearrangement often produces chromosomes with two centromeres (dicentrics) that are inherently unstable because of bridge formation and breakage during cell division. However, mammalian dicentrics, and particularly those in humans, can be quite stable, usually because one centromere is functionally silenced. Molecular mechanisms of centromere inactivation are poorly understood since there are few systems to experimentally create dicentric human chromosomes. Here, we describe a human cell culture model that enriches for de novo dicentrics. We demonstrate that transient disruption of human telomere structure non-randomly produces dicentric fusions involving acrocentric chromosomes. The induced dicentrics vary in structure near fusion breakpoints and like naturally-occurring dicentrics, exhibit various inter-centromeric distances. Many functional dicentrics persist for months after formation. Even those with distantly spaced centromeres remain functionally dicentric for 20 cell generations. Other dicentrics within the population reflect centromere inactivation. In some cases, centromere inactivation occurs by an apparently epigenetic mechanism. In other dicentrics, the size of the α-satellite DNA array associated with CENP-A is reduced compared to the same array before dicentric formation. Extra-chromosomal fragments that contained CENP-A often appear in the same cells as dicentrics. Some of these fragments are derived from the same α-satellite DNA array as inactivated centromeres. Our results indicate that dicentric human chromosomes undergo alternative fates after formation. Many retain two active centromeres and are stable through multiple cell divisions. Others undergo centromere inactivation. This event occurs within a broad temporal window and can involve deletion of chromatin that marks the locus as a site for CENP-A maintenance/replenishment. Endogenous human centromeres are defined by large arrays of α-satellite DNA. A portion of each α-satellite array is assembled into CENP-A chromatin, the structural and functional platform for kinetochore formation. Most chromosomes are monocentric, meaning they have a single centromere. However, genome rearrangement can produce chromosomes with two centromeres (dicentrics). In most organisms, dicentrics typically break during cell division; however, dicentric human chromosomes can be stable in mitosis and meiosis. This stability reflects centromere inactivation, a poorly understood phenomenon in which one centromere is functionally silenced. To explore molecular and genomic events that occur at the time of dicentric formation, we describe a cell-based system to create dicentric human chromosomes and monitor their behavior after formation. Such dicentrics can experience several fates, including centromere inactivation, breakage, or maintaining two functional centromeres. Unexpectedly, we also find that dicentrics with large (>20Mb) inter-centromeric distances are stable through at least 20 cell divisions. Our results highlight similarities and differences in dicentric behavior between humans and model organisms, and they provide evidence for one mechanism of centromere inactivation by centromeric deletion in some dicentrics. The ability to create dicentric human chromosomes provides a system to test other mechanisms of centromere disassembly and dicentric chromosome stability.
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Affiliation(s)
- Kaitlin M. Stimpson
- Duke Institute for Genome Sciences and Policy, Duke University, Durham, North Carolina, United States of America
| | - Ihn Young Song
- Department of Genetics and Genomics, Boston University School of Medicine, Boston, Massachusetts, United States of America
| | - Anna Jauch
- Institute of Human Genetics, University Hospital Heidelberg, Heidelberg, Germany
| | - Heidi Holtgreve-Grez
- Institute of Human Genetics, University Hospital Heidelberg, Heidelberg, Germany
| | - Karen E. Hayden
- Duke Institute for Genome Sciences and Policy, Duke University, Durham, North Carolina, United States of America
| | - Joanna M. Bridger
- Laboratory of Nuclear and Genomic Health, Centre for Cell and Chromosome Biology, Division of Biosciences, Brunel University, Uxbridge, United Kingdom
| | - Beth A. Sullivan
- Duke Institute for Genome Sciences and Policy, Duke University, Durham, North Carolina, United States of America
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina, United States of America
- * E-mail:
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Stimpson KM, Sullivan BA. Epigenomics of centromere assembly and function. Curr Opin Cell Biol 2010; 22:772-80. [PMID: 20675111 DOI: 10.1016/j.ceb.2010.07.002] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2010] [Accepted: 07/04/2010] [Indexed: 12/13/2022]
Abstract
The centromere is a complex chromosomal locus where the kinetochore is formed and microtubules attach during cell division. Centromere identity involves both genomic and sequence-independent (epigenetic) mechanisms. Current models for how centromeres are formed and, conversely, turned off have emerged from studies of unusual or engineered chromosomes, such as neocentromeres, artificial chromosomes, and dicentric chromosomes. Recent studies have highlighted the importance of unique chromatin marked by the histone H3 variant CENP-A, classical chromatin (heterochromatin and euchromatin), and transcription during centromere activation and inactivation. These advances have deepened our view of what defines a centromere and how it behaves in various genomic and chromatin contexts.
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Affiliation(s)
- Kaitlin M Stimpson
- Duke Institute for Genome Sciences & Policy and Department of Molecular Genetics and Microbiology, Duke University, 101 Science Drive, Box 3382, Durham, NC 27708, USA
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Anders KR, Kudrna JR, Keller KE, Kinghorn B, Miller EM, Pauw D, Peck AT, Shellooe CE, Strong IJT. A strategy for constructing aneuploid yeast strains by transient nondisjunction of a target chromosome. BMC Genet 2009; 10:36. [PMID: 19594932 PMCID: PMC2725114 DOI: 10.1186/1471-2156-10-36] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2009] [Accepted: 07/13/2009] [Indexed: 11/24/2022] Open
Abstract
Background Most methods for constructing aneuploid yeast strains that have gained a specific chromosome rely on spontaneous failures of cell division fidelity. In Saccharomyces cerevisiae, extra chromosomes can be obtained when errors in meiosis or mitosis lead to nondisjunction, or when nuclear breakdown occurs in heterokaryons. We describe a strategy for constructing N+1 disomes that does not require such spontaneous failures. The method combines two well-characterized genetic tools: a conditional centromere that transiently blocks disjunction of one specific chromosome, and a duplication marker assay that identifies disomes among daughter cells. To test the strategy, we targeted chromosomes III, IV, and VI for duplication. Results The centromere of each chromosome was replaced by a centromere that can be blocked by growth in galactose, and ura3::HIS3, a duplication marker. Transient exposure to galactose induced the appearance of colonies carrying duplicated markers for chromosomes III or IV, but not VI. Microarray-based comparative genomic hybridization (CGH) confirmed that disomic strains carrying extra chromosome III or IV were generated. Chromosome VI contains several genes that are known to be deleterious when overexpressed, including the beta-tubulin gene TUB2. To test whether a tubulin stoichiometry imbalance is necessary for the apparent lethality caused by an extra chromosome VI, we supplied the parent strain with extra copies of the alpha-tubulin gene TUB1, then induced nondisjunction. Galactose-dependent chromosome VI disomes were produced, as revealed by CGH. Some chromosome VI disomes also carried extra, unselected copies of additional chromosomes. Conclusion This method causes efficient nondisjunction of a targeted chromosome and allows resulting disomic cells to be identified and maintained. We used the method to test the role of tubulin imbalance in the apparent lethality of disomic chromosome VI. Our results indicate that a tubulin imbalance is necessary for disomic VI lethality, but it may not be the only dosage-dependent effect.
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Affiliation(s)
- Kirk R Anders
- Biology Department, Gonzaga University, Spokane, WA 99258, USA.
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Neurohr G, Gerlich DW. Assays for mitotic chromosome condensation in live yeast and mammalian cells. Chromosome Res 2009; 17:145-54. [PMID: 19308697 DOI: 10.1007/s10577-008-9010-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The dynamic reorganization of chromatin into rigid and compact mitotic chromosomes is of fundamental importance for faithful chromosome segregation. Owing to the difficulty of investigating this process under physiological conditions, the exact morphological transitions and the molecular machinery driving chromosome condensation remain poorly defined. Here, we review how imaging-based methods can be used to quantitate chromosome condensation in vivo, focusing on yeast and animal tissue culture cells as widely used model systems. We discuss approaches how to address structural dynamics of condensing chromosomes and chromosome segments, as well as to probe for mechanical properties of mitotic chromosomes. Application of such methods to systematic perturbation studies will provide a means to reveal the molecular networks underlying the regulation of mitotic chromosome condensation.
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Affiliation(s)
- Gabriel Neurohr
- Institute of Biochemistry, Swiss Institute of Technology Zurich (ETHZ), Schafmattstr. 18, CH-8093 Zurich, Switzerland
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Neocentromeres form efficiently at multiple possible loci in Candida albicans. PLoS Genet 2009; 5:e1000400. [PMID: 19266018 PMCID: PMC2642679 DOI: 10.1371/journal.pgen.1000400] [Citation(s) in RCA: 143] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2008] [Accepted: 02/03/2009] [Indexed: 12/20/2022] Open
Abstract
Centromeres are critically important for chromosome stability and integrity. Most eukaryotes have regional centromeres that include long tracts of repetitive DNA packaged into pericentric heterochromatin. Neocentromeres, new sites of functional kinetochore assembly, can form at ectopic loci because no DNA sequence is strictly required for assembly of a functional kinetochore. In humans, neocentromeres often arise in cells with gross chromosome rearrangements that rescue an acentric chromosome. Here, we studied the properties of centromeres in Candida albicans, the most prevalent fungal pathogen of humans, which has small regional centromeres that lack pericentric heterochromatin. We functionally delimited centromere DNA on Chromosome 5 (CEN5) and then replaced the entire region with the counter-selectable URA3 gene or other marker genes. All of the resulting cen5Δ::URA3 transformants stably retained both copies of Chr5, indicating that a functional neocentromere had assembled efficiently on the homolog lacking CEN5 DNA. Strains selected to maintain only the cen5Δ::URA3 homolog and no wild-type Chr5 homolog also grew well, indicating that neocentromere function is independent of the presence of any wild-type CEN5 DNA. Two classes of neocentromere (neoCEN) strains were distinguishable: “proximal neoCEN” and “distal neoCEN” strains. Neocentromeres in the distal neoCEN strains formed at loci about 200–450 kb from cen5Δ::URA3 on either chromosome arm, as detected by massively parallel sequencing of DNA isolated by CENP-ACse4p chromatin immunoprecipitation (ChIP). In the proximal neoCEN strains, the neocentromeres formed directly adjacent to cen5Δ::URA3 and moved onto the URA3 DNA, resulting in silencing of its expression. Functional neocentromeres form efficiently at several possible loci that share properties of low gene density and flanking repeated DNA sequences. Subsequently, neocentromeres can move locally, which can be detected by silencing of an adjacent URA3 gene, or can relocate to entirely different regions of the chromosome. The ability to select for neocentromere formation and movement in C. albicans permits mechanistic analysis of the assembly and maintenance of a regional centromere. Centromere function is essential for proper chromosomal segregation. Most organisms, including humans, have regional centromeres in which centromere function is not strictly dependent on DNA sequence. Upon alteration of chromosomes, new functional centromeres (neocentromeres) can form at ectopic positions. The mechanisms of neocentromere formation are not understood, primarily because neocentromere formation is rarely detected. Here. we show that C. albicans, an important fungal pathogen of humans, has small regional centromeres and can form neocentromeres very efficiently when normal centromere DNA is deleted, and the resulting chromosomes are stably propagated. Neocentromeres can form either very close to the position of the deleted centromere or at other positions along the chromosome arms, including at the telomeres. Subsequently, neocentromeres can move to new chromosomal positions, and this movement can be detected by silencing of a counterselectable gene. The features common to sites of neocentromere formation are longer-than-average intergenic regions and the proximity of inverted or direct repeat sequences. The ability to select for neocentromere formation and movement in C. albicans permits mechanistic analysis of the assembly and maintenance of a regional centromere.
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Gardner MK, Haase J, Mythreye K, Molk JN, Anderson M, Joglekar AP, O'Toole ET, Winey M, Salmon ED, Odde DJ, Bloom K. The microtubule-based motor Kar3 and plus end-binding protein Bim1 provide structural support for the anaphase spindle. ACTA ACUST UNITED AC 2008; 180:91-100. [PMID: 18180364 PMCID: PMC2213616 DOI: 10.1083/jcb.200710164] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In budding yeast, the mitotic spindle is comprised of 32 kinetochore microtubules (kMTs) and approximately 8 interpolar MTs (ipMTs). Upon anaphase onset, kMTs shorten to the pole, whereas ipMTs increase in length. Overlapping MTs are responsible for the maintenance of spindle integrity during anaphase. To dissect the requirements for anaphase spindle stability, we introduced a conditionally functional dicentric chromosome into yeast. When centromeres from the same sister chromatid attach to opposite poles, anaphase spindle elongation is delayed and a DNA breakage-fusion-bridge cycle ensues that is dependent on DNA repair proteins. We find that cell survival after dicentric chromosome activation requires the MT-binding proteins Kar3p, Bim1p, and Ase1p. In their absence, anaphase spindles are prone to collapse and buckle in the presence of a dicentric chromosome. Our analysis reveals the importance of Bim1p in maintaining a stable ipMT overlap zone by promoting polymerization of ipMTs during anaphase, whereas Kar3p contributes to spindle stability by cross-linking spindle MTs.
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Affiliation(s)
- Melissa K Gardner
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN 55455, USA
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Ray S, Chatterjee A. Influence of glutathione on the induction of chromosome aberrations, delay in cell cycle kinetics and cell cycle regulator proteins in irradiated mouse bone marrow cells. Int J Radiat Biol 2007; 83:347-54. [PMID: 17457759 DOI: 10.1080/09553000701317887] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
PURPOSE Reduced glutathione (GSH) is an endogenous thiol and has long been thought to affect the sensitivity of cells to radiation. The aim was to see the influence of GSH on: (i) the production of all types of radiation-induced chromosome aberrations (CA), and (ii) the radiation-induced delay in cell cycle and the levels of cell cycle regulator proteins. MATERIALS AND METHODS Cell cycle kinetics were determined by scoring the mitotic index (MI). CA and MI were scored in gamma-irradiated buthionine sulfoximine (BSO) (10 h) or GSH (1 h) pretreated and untreated mouse bone marrow cells (BMC). The expression of p53 and p21 proteins after 2 and 6 h of irradiation and for the B-cell lymphoma 2 (Bcl-2) associated X-protein (Bax) after 24 h of irradiation with or without BSO or GSH treatment was analyzed by immunoblotting. RESULTS Radiation delays mouse BMC in their passage through the cell cycle and induces CA. Exogenous addition of GSH protected CA uniformly at lower doses of radiation but differentially at higher doses, whereas GSH-depletion by BSO increased the frequency of radiation-induced CA. Both GSH and BSO-pretreated cells reduced the delay in cell kinetics after irradiation. Levels of both p53 and p21 were enhanced after irradiation to BSO-pretreated cells. However, in GSH-pretreated cells the level of these proteins was reduced. CONCLUSION Data indicate that the induction of CA and delay in cell kinetics by radiation may not always be interlinked and that the level of endogenous GSH exerts its influence on these parameters. Both GSH and BSO pretreatment reduce delays in cell kinetics of irradiated cells which may die apoptotically, since they have either a higher frequency of exchange aberrations or CA, respectively.
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Affiliation(s)
- S Ray
- Genetics Laboratory, Department of Zoology, North-Eastern Hill University, Shillong, India
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Collins KA, Castillo AR, Tatsutani SY, Biggins S. De novo kinetochore assembly requires the centromeric histone H3 variant. Mol Biol Cell 2005; 16:5649-60. [PMID: 16207811 PMCID: PMC1289410 DOI: 10.1091/mbc.e05-08-0771] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Kinetochores mediate chromosome attachment to the mitotic spindle to ensure accurate chromosome segregation. Budding yeast is an excellent organism for kinetochore assembly studies because it has a simple defined centromere sequence responsible for the localization of >65 proteins. In addition, yeast is the only organism where a conditional centromere is available to allow studies of de novo kinetochore assembly. Using a conditional centromere, we found that yeast kinetochore assembly is not temporally restricted and can occur in both G1 phase and prometaphase. We performed the first investigation of kinetochore assembly in the absence of the centromeric histone H3 variant Cse4 and found that all proteins tested depend on Cse4 to localize. Consistent with this observation, Cse4-depleted cells had severe chromosome segregation defects. We therefore propose that yeast kinetochore assembly requires both centromeric DNA specificity and centromeric chromatin.
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Affiliation(s)
- Kimberly A Collins
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA 98109-1042, USA
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Thrower DA, Stemple J, Yeh E, Bloom K. Nuclear oscillations and nuclear filament formation accompany single-strand annealing repair of a dicentric chromosome in Saccharomyces cerevisiae. J Cell Sci 2003; 116:561-9. [PMID: 12508116 DOI: 10.1242/jcs.00251] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Dicentric chromosomes undergo breakage during mitosis as a result of the attachment of two centromeres on one sister chromatid to opposite spindle poles. Studies utilizing a conditional dicentric chromosome III in Saccharomyces cerevisiae have shown that dicentric chromosome repair occurs primarily by deletion of one centromere via a RAD52-dependent recombination pathway. We report that dicentric chromosome resolution requires RAD1, a gene involved in the single-strand annealing DNA repair pathway. We additionally show that single-strand annealing repair of a dicentric chromosome can occur in the absence of RAD52. RAD52-independent repair requires the adaptation-defective cdc5-ad allele of the yeast polo kinase and the DNA damage checkpoint gene RAD9. Dicentric chromosome breakage in cdc5-ad rad52 mutant cells is associated with a prolonged mitotic arrest, during which nuclei undergo microtubule-dependent oscillations, accompanied by dynamic changes in nuclear morphology. We further demonstrate that the frequency of spontaneous direct repeat recombination is suppressed in yeast cells treated with benomyl, a drug that perturbs microtubules. Our findings indicate that microtubule-dependent processes facilitate recombination.
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Affiliation(s)
- Douglas A Thrower
- Department of Biology, CB3280 University of North Carolina, Chapel Hill, NC 27599-3280, USA
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36
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Thrower DA, Bloom K. Dicentric chromosome stretching during anaphase reveals roles of Sir2/Ku in chromatin compaction in budding yeast. Mol Biol Cell 2001; 12:2800-12. [PMID: 11553718 PMCID: PMC59714 DOI: 10.1091/mbc.12.9.2800] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
We have used mitotic spindle forces to examine the role of Sir2 and Ku in chromatin compaction. Escherichia coli lac operator DNA was placed between two centromeres on a conditional dicentric chromosome in budding yeast cells and made visible by expression of a lac repressor-green fluorescent fusion protein. Centromeres on the same chromatid of a dicentric chromosome attach to opposite poles approximately 50% of the time, resulting in chromosome bridges during anaphase. In cells deleted for yKU70, yKU80, or SIR2, a 10-kb region of the dicentric chromosome stretched along the spindle axis to a length of 6 microm during anaphase. On spindle disassembly, stretched chromatin recoiled to the bud neck and was partitioned to mother and daughter cells after cytokinesis and cell separation. Chromatin immunoprecipitation revealed that Sir2 localizes to the lacO region in response to activation of the dicentric chromosome. These findings indicate that Ku and Sir proteins are required for proper chromatin compaction within regions of a chromosome experiencing tension or DNA damage. The association of Sir2 with the affected region suggests a direct role in this process, which may include the formation of heterochromatic DNA.
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Affiliation(s)
- D A Thrower
- Department of Biology, CB3280 University of North Carolina, Chapel Hill, NC 27599-3280, USA
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Tanaka T, Cosma MP, Wirth K, Nasmyth K. Identification of cohesin association sites at centromeres and along chromosome arms. Cell 1999; 98:847-58. [PMID: 10499801 DOI: 10.1016/s0092-8674(00)81518-4] [Citation(s) in RCA: 238] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
A multisubunit cohesin complex holds sister chromatids together after DNA replication. Using chromatin immunoprecipitation, we detected cohesin association with centromeres and with discrete sites along chromosome arms from S phase until metaphase in S. cerevisiae. Short DNA sequences (130-280 bp) are sufficient to confer cohesin association. Cohesin association with a centromere depends on Mif2p, the centromere binding factor CBF3, and a centromere-specific histone variant, Cse4p. Because only active centromeres confer cohesin association with centromeric DNA, we suggest that cohesin is recruited by the same chromatin structure that confers the attachment of microtubules. Propagation of this structure might be partly epigenetic. Finally, cohesion associated with "minimal" centromeres is insufficient to resist the splitting force exerted by microtubules and appears to be reinforced by cohesion provided by their flanking DNA sequences.
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Affiliation(s)
- T Tanaka
- Research Institute of Molecular Pathology, Vienna, Austria
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Abstract
Activation of a facultative, dicentric chromosome provides a unique opportunity to introduce a double strand DNA break into a chromosome at mitosis. Time lapse video enhanced-differential interference contrast analysis of the cellular response upon dicentric activation reveals that the majority of cells initiates anaphase B, characterized by pole-pole separation, and pauses in mid-anaphase for 30-120 min with spindles spanning the neck of the bud before completing spindle elongation and cytokinesis. The length of the spindle at the delay point (3-4 microm) is not dependent on the physical distance between the two centromeres, indicating that the arrest represents surveillance of a dicentric induced aberration. No mid-anaphase delay is observed in the absence of the RAD9 checkpoint gene, which prevents cell cycle progression in the presence of damaged DNA. These observations reveal RAD9-dependent events well past the G2/M boundary and have considerable implications in understanding how chromosome integrity and the position and state of the mitotic spindle are monitored before cytokinesis.
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Affiliation(s)
- S S Yang
- Department of Biology, University of North Carolina, Chapel Hill 27599-3280, USA
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Widianto D, Yamamoto E, Mukai Y, Oshima Y, Harashima S. A method for fusing chromosomes in Saccharomyces cerevisiae. ACTA ACUST UNITED AC 1997. [DOI: 10.1016/s0922-338x(97)83570-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Porter G, Westmoreland J, Priebe S, Resnick MA. Homologous and homeologous intermolecular gene conversion are not differentially affected by mutations in the DNA damage or the mismatch repair genes RAD1, RAD50, RAD51, RAD52, RAD54, PMS1 and MSH2. Genetics 1996; 143:755-67. [PMID: 8725224 PMCID: PMC1207334 DOI: 10.1093/genetics/143.2.755] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Mismatch repair (MMR) genes or genes involved in both DNA damage repair and homologous recombination might affect homeologous vs. homologous recombination differentially. Spontaneous mitotic gene conversion between a chromosome and a homologous or homeologous donor sequence (14% diverged) on a single copy plasmid was examined in wild-type Saccharomyces cerevisiae strains and in MMR or DNA damage repair mutants. Homologous recombination in rad51, rad52 and rad54 mutants was considerably reduced, while there was little effect of rad1, rad50, pms1 and msh2 null mutations. DNA divergence resulted in no differential effect on recombination rates in the wild type or the mutants; there was only a five to 10-fold reduction in homeologous relative to homologous recombination regardless of background. Since DNA divergence is known to affect recombination in some systems, we propose that differences in the role of MMR depends on the mode of recombination and/or the level of divergence. Based on analysis of the recombination breakpoints, there is a minimum of three homologous bases required at a recombination junction. A comparison of Rad+ vs. rad52 strains revealed that while all conversion tracts are continuous, elimination of RAD52 leads to the appearance of a novel class of very short conversion tracts.
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Affiliation(s)
- G Porter
- Laboratory of Molecular Genetics, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709, USA
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Flatters M, Maxfield R, Dawson D. The effects of a ring chromosome on the meiotic segregation of other chromosomes in Saccharomyces cerevisiae. MOLECULAR & GENERAL GENETICS : MGG 1995; 249:309-16. [PMID: 7500956 DOI: 10.1007/bf00290532] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Meiotic chromosome segregation must occur with high fidelity in order to prevent the generation of aneuploid cells. We have previously described the identification and genetic characterization of a yeast mutant with defects in meiotic sister-chromatid segregation. We attributed the phenotype in this mutant to a dominant allele, which we referred to as SID1-1. These mutants appeared to exhibit high levels of non-disjunction and precocious separation of sister-chromatids of chromosome III, as well as precocious separation of sister chromatids of chromosome VIII and a univalent artificial chromosome. We show here that the unusual meiotic behavior of chromosome III in these strains is due to the presence of a ring III chromosome, rather than a mutant gene. Additional experiments demonstrate that a ring III/rod III pair alters the meiotic segregation of a univalent artificial chromosome.
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Affiliation(s)
- M Flatters
- Department of Molecular Biology and Microbiology, Tufts University, Boston, MA 02111, USA
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Dresser ME, Ewing DJ, Harwell SN, Coody D, Conrad MN. Nonhomologous synapsis and reduced crossing over in a heterozygous paracentric inversion in Saccharomyces cerevisiae. Genetics 1994; 138:633-47. [PMID: 7851761 PMCID: PMC1206214 DOI: 10.1093/genetics/138.3.633] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Homologous chromosome synapsis ("homosynapsis") and crossing over are well-conserved aspects of meiotic chromosome behavior. The long-standing assumption that these two processes are causally related has been challenged recently by observations in Saccharomyces cerevisiae of significant levels of crossing over (1) between small sequences at nonhomologous locations and (2) in mutants where synapsis is abnormal or absent. In order to avoid problems of local sequence effects and of mutation pleiotropy, we have perturbed synapsis by making a set of isogenic strains that are heterozygous and homozygous for a large chromosomal paracentric inversion covering a well marked genetic interval and then measured recombination. We find that reciprocal recombination in the marked interval in heterozygotes is reduced variably across the interval, on average to approximately 55% of that in the homozygotes, and that positive interference still modulates crossing over. Cytologically, stable synapsis across the interval is apparently heterologous rather than homologous, consistent with the interpretation that stable homosynapsis is required to initiate or consummate a large fraction of the crossing over observed in wild-type strains. When crossing over does occur in heterozygotes, dicentric and acentric chromosomes are formed and can be visualized and quantitated on blots though not demonstrated in viable spores. We find that there is no loss of dicentric chromosomes during the two meiotic divisions and that the acentric chromosome is recovered at only 1/3 to 1/2 of the expected level.
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Affiliation(s)
- M E Dresser
- Program in Molecular and Cell Biology, Oklahoma Medical Research Foundation, Oklahoma City 73104
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Brock JA, Bloom K. A chromosome breakage assay to monitor mitotic forces in budding yeast. J Cell Sci 1994; 107 ( Pt 4):891-902. [PMID: 8056845 DOI: 10.1242/jcs.107.4.891] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
During the eukaryotic cell cycle, genetic material must be accurately duplicated and faithfully segregated to each daughter cell. Segregation of chromosomes is dependent on the centromere, a region of the chromosome which interacts with mitotic spindle microtubules during cell division. Centromere function in the budding yeast, Saccharomyces cerevisiae, can be regulated by placing an inducible promotor adjacent to centromere DNA. This conditional centromere can be integrated into chromosome III to generate a conditionally functional dicentric chromosome. Activation of the dicentric chromosome results in a transient mitotic delay followed by the generation of monocentric derivatives. The propagation of viable cells containing these monocentric derivative chromosomes is dependent upon the DNA repair gene RAD52, indicating that double-strand DNA breaks are structural intermediates in the dicentric repair pathway. We have used these conditionally dicentric chromosomes to monitor the exertion of mitotic forces during cell division. Analysis of synchronized cells reveal that lethality in dicentric, rad52 mutant cells occurs during G2/M phase and is concomitant with the transient mitotic delay. the delay is largely dependent upon the cell cycle checkpoint gene RAD9, which is involved in monitoring DNA damage. These data demonstrate that DNA lesions resulting from dicentric activation are responsible for signalling the mitotic delay. Since the delay precedes the decline of p34cdc28 kinase activity, mitotic forces sufficient to result in dicentric chromosome breakage are generated prior to spindle elongation and anaphase onset in yeast.
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Affiliation(s)
- J A Brock
- Department of Biology, University of North Carolina, Chapel Hill 27599-3280
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Wicksteed BL, Collins I, Dershowitz A, Stateva LI, Green RP, Oliver SG, Brown AJ, Newlon CS. A physical comparison of chromosome III in six strains of Saccharomyces cerevisiae. Yeast 1994; 10:39-57. [PMID: 8203151 DOI: 10.1002/yea.320100105] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
We have tested the clones used in the European Yeast Chromosome III Sequencing Programme for possible artefacts that might have been introduced during cloning or passage through Escherichia coli. Southern analysis was performed to compare the BamHI, EcoRI, HindIII and PstI restriction pattern for each clone with that of the corresponding locus on chromosome III in the parental yeast strain. In addition, further enzymes were used to compare the restriction maps of most clones with the map predicted by the nucleotide sequence (Oliver et al., 1992). Only four of 506 6-bp restriction sites predicted by the sequence were not observed experimentally. No significant cloning artefacts appear to disrupt the published sequence of chromosome III. The restriction patterns of six yeast strains have also been compared. In addition to two previously identified sites of Ty integration on chromosome III (Warmington et al., 1986; Stucka et al., 1989; Newlon et al., 1991), a new polymorphic site involving Ty retrotransposition (the Far Right-Arm transposition Hot-Spot, FRAHS) has been identified close to CRY1. On the basis of simple restriction polymorphisms, the strains S288C, AB972 and W303-1b are closely related, while XJ24-24a and J178 are more distant relatives of S288C. A polyploid distillery yeast is heterozygous for many polymorphisms, particularly on the right arm of the chromosome.
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Kouprina N, Kirillov A, Kroll E, Koryabin M, Shestopalov B, Bannikov V, Zakharyev V, Larionov V. Identification and cloning of the CHL4 gene controlling chromosome segregation in yeast. Genetics 1993; 135:327-41. [PMID: 8243998 PMCID: PMC1205639 DOI: 10.1093/genetics/135.2.327] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
A collection of chl mutants characterized by decreased fidelity of chromosome transmission and by minichromosome nondisjunction in mitosis was examined for the ability to maintain nonessential dicentric plasmids. In one of the seven mutants analyzed, chl4, dicentric plasmids did not depress cell division. Moreover, nonessential dicentric plasmids were maintained stably without any rearrangements during many generations in the chl4 mutant. The rate of mitotic heteroallelic recombination in the chl4 mutant was not increased compared to that in an isogenic wild-type strain. Analysis of the segregation of a marked chromosome indicated that sister chromatid nondisjunction and sister chromatid loss contributed equally to chromosome malsegregation in the chl4 mutant. A genomic clone of CHL4 was isolated by complementation of the chl4-1 mutation and was physically mapped to the right arm of chromosome IV near the SUP2 gene. Nucleotide sequence analysis of CHL4 clone revealed a 1.4-kb open reading frame coding for a 53-kD predicted protein which does not have homology to published proteins. A strain containing a null allele of CHL4 is viable under standard growth conditions but has a temperature-sensitive phenotype (conditional lethality at 36 degrees). We suggest that the CHL4 gene is required for kinetochore function in the yeast Saccharomyces cerevisiae.
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Affiliation(s)
- N Kouprina
- Institute of Cytology, Russian Academy of Sciences, St. Petersburg
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Bloom K. The centromere frontier: kinetochore components, microtubule-based motility, and the CEN-value paradox. Cell 1993; 73:621-4. [PMID: 8500159 DOI: 10.1016/0092-8674(93)90242-i] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Affiliation(s)
- K Bloom
- Department of Biology, University of North Carolina, Chapel Hill 27599-3280
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