1
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Lim KK, Lam UTF, Li Y, Zeng YB, Yang H, Chen ES. Set2 regulates Ccp1 and Swc2 to ensure centromeric stability by retargeting CENP-A. Nucleic Acids Res 2024; 52:4198-4214. [PMID: 38442274 PMCID: PMC11077061 DOI: 10.1093/nar/gkae084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Revised: 01/24/2024] [Accepted: 01/29/2024] [Indexed: 03/07/2024] Open
Abstract
Precise positioning of the histone-H3 variant, CENP-A, ensures centromere stability and faithful chromosomal segregation. Mislocalization of CENP-A to extra-centromeric loci results in aneuploidy and compromised cell viability associated with formation of ectopic kinetochores. The mechanism that retargets mislocalized CENP-A back to the centromere is unclarified. We show here that the downregulation of the histone H3 lysine 36 (H3K36) methyltransferase Set2 can preserve centromere localization of a temperature-sensitive mutant cnp1-1 Schizosaccharomyces pombe CENP-A (SpCENP-A) protein and reverse aneuploidy by redirecting mislocalized SpCENP-A back to centromere from ribosomal DNA (rDNA) loci, which serves as a sink for the delocalized SpCENP-A. Downregulation of set2 augments Swc2 (SWR1 complex DNA-binding module) expression and releases histone chaperone Ccp1 from the centromeric reservoir. Swc2 and Ccp1 are directed to the rDNA locus to excavate the SpCENP-Acnp1-1, which is relocalized to the centromere in a manner dependent on canonical SpCENP-A loaders, including Mis16, Mis17 and Mis18, thereby conferring cell survival and safeguarding chromosome segregation fidelity. Chromosome missegregation is a severe genetic instability event that compromises cell viability. This mechanism thus promotes CENP-A presence at the centromere to maintain genomic stability.
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Affiliation(s)
- Kim Kiat Lim
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Ulysses Tsz Fung Lam
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Ying Li
- NUS Center for Cancer Research, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
- Cancer Science Institute, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Yi Bing Zeng
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Henry Yang
- NUS Center for Cancer Research, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
- Cancer Science Institute, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
- National University Health System, Singapore
| | - Ee Sin Chen
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
- NUS Center for Cancer Research, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
- National University Health System, Singapore
- Integrative Sciences & Engineering Programme, National University of Singapore, Singapore
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2
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Folco H, Xiao H, Wheeler D, Feng H, Bai Y, Grewal SS. The cysteine-rich domain in CENP-A chaperone Scm3HJURP ensures centromere targeting and kinetochore integrity. Nucleic Acids Res 2024; 52:1688-1701. [PMID: 38084929 PMCID: PMC10899784 DOI: 10.1093/nar/gkad1182] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2023] [Revised: 11/20/2023] [Accepted: 11/28/2023] [Indexed: 02/29/2024] Open
Abstract
Centromeric chromatin plays a crucial role in kinetochore assembly and chromosome segregation. Centromeres are specified through the loading of the histone H3 variant CENP-A by the conserved chaperone Scm3/HJURP. The N-terminus of Scm3/HJURP interacts with CENP-A, while the C-terminus facilitates centromere localization by interacting with the Mis18 holocomplex via a small domain, called the Mis16-binding domain (Mis16-BD) in fission yeast. Fungal Scm3 proteins contain an additional conserved cysteine-rich domain (CYS) of unknown function. Here, we find that CYS binds zinc in vitro and is essential for the localization and function of fission yeast Scm3. Disrupting CYS by deletion or introduction of point mutations within its zinc-binding motif prevents Scm3 centromere localization and compromises kinetochore integrity. Interestingly, CYS alone can localize to the centromere, albeit weakly, but its targeting is greatly enhanced when combined with Mis16-BD. Expressing a truncated protein containing both Mis16-BD and CYS, but lacking the CENP-A binding domain, causes toxicity and is accompanied by considerable chromosome missegregation and kinetochore loss. These effects can be mitigated by mutating the CYS zinc-binding motif. Collectively, our findings establish the essential role of the cysteine-rich domain in fungal Scm3 proteins and provide valuable insights into the mechanism of Scm3 centromere targeting.
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Affiliation(s)
- H Diego Folco
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Hua Xiao
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - David Wheeler
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Hanqiao Feng
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Yawen Bai
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Shiv I S Grewal
- Laboratory of Biochemistry and Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
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3
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Kuse R, Ishii K. Flexible Attachment and Detachment of Centromeres and Telomeres to and from Chromosomes. Biomolecules 2023; 13:1016. [PMID: 37371596 DOI: 10.3390/biom13061016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2023] [Revised: 06/15/2023] [Accepted: 06/18/2023] [Indexed: 06/29/2023] Open
Abstract
Accurate transmission of genomic information across multiple cell divisions and generations, without any losses or errors, is fundamental to all living organisms. To achieve this goal, eukaryotes devised chromosomes. Eukaryotic genomes are represented by multiple linear chromosomes in the nucleus, each carrying a centromere in the middle, a telomere at both ends, and multiple origins of replication along the chromosome arms. Although all three of these DNA elements are indispensable for chromosome function, centromeres and telomeres possess the potential to detach from the original chromosome and attach to new chromosomal positions, as evident from the events of telomere fusion, centromere inactivation, telomere healing, and neocentromere formation. These events seem to occur spontaneously in nature but have not yet been elucidated clearly, because they are relatively infrequent and sometimes detrimental. To address this issue, experimental setups have been developed using model organisms such as yeast. In this article, we review some of the key experiments that provide clues as to the extent to which these paradoxical and elusive features of chromosomally indispensable elements may become valuable in the natural context.
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Affiliation(s)
- Riku Kuse
- Laboratory of Chromosome Function and Regulation, Graduate School of Engineering, Kochi University of Technology, Kochi 782-8502, Japan
| | - Kojiro Ishii
- Laboratory of Chromosome Function and Regulation, Graduate School of Engineering, Kochi University of Technology, Kochi 782-8502, Japan
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4
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Wu W, McHugh T, Kelly DA, Pidoux AL, Allshire RC. Establishment of centromere identity is dependent on nuclear spatial organization. Curr Biol 2022; 32:3121-3136.e6. [PMID: 35830853 PMCID: PMC9616734 DOI: 10.1016/j.cub.2022.06.048] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2021] [Revised: 04/24/2022] [Accepted: 06/15/2022] [Indexed: 11/15/2022]
Abstract
The establishment of centromere-specific CENP-A chromatin is influenced by epigenetic and genetic processes. Central domain sequences from fission yeast centromeres are preferred substrates for CENP-ACnp1 incorporation, but their use is context dependent, requiring adjacent heterochromatin. CENP-ACnp1 overexpression bypasses heterochromatin dependency, suggesting that heterochromatin ensures exposure to conditions or locations permissive for CENP-ACnp1 assembly. Centromeres cluster around spindle-pole bodies (SPBs). We show that heterochromatin-bearing minichromosomes localize close to SPBs, consistent with this location promoting CENP-ACnp1 incorporation. We demonstrate that heterochromatin-independent de novo CENP-ACnp1 chromatin assembly occurs when central domain DNA is placed near, but not far from, endogenous centromeres or neocentromeres. Moreover, direct tethering of central domain DNA at SPBs permits CENP-ACnp1 assembly, suggesting that the nuclear compartment surrounding SPBs is permissive for CENP-ACnp1 incorporation because target sequences are exposed to high levels of CENP-ACnp1 and associated assembly factors. Thus, nuclear spatial organization is a key epigenetic factor that influences centromere identity.
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Affiliation(s)
- Weifang Wu
- Wellcome Trust Centre for Cell Biology, Institute of Cell Biology, School of Biological Sciences, The University of Edinburgh, Edinburgh EH9 3BF, Scotland, UK
| | - Toni McHugh
- Wellcome Trust Centre for Cell Biology, Institute of Cell Biology, School of Biological Sciences, The University of Edinburgh, Edinburgh EH9 3BF, Scotland, UK
| | - David A Kelly
- Wellcome Trust Centre for Cell Biology, Institute of Cell Biology, School of Biological Sciences, The University of Edinburgh, Edinburgh EH9 3BF, Scotland, UK
| | - Alison L Pidoux
- Wellcome Trust Centre for Cell Biology, Institute of Cell Biology, School of Biological Sciences, The University of Edinburgh, Edinburgh EH9 3BF, Scotland, UK
| | - Robin C Allshire
- Wellcome Trust Centre for Cell Biology, Institute of Cell Biology, School of Biological Sciences, The University of Edinburgh, Edinburgh EH9 3BF, Scotland, UK.
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5
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The ins and outs of CENP-A: Chromatin dynamics of the centromere-specific histone. Semin Cell Dev Biol 2022; 135:24-34. [PMID: 35422390 DOI: 10.1016/j.semcdb.2022.04.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Revised: 04/05/2022] [Accepted: 04/05/2022] [Indexed: 01/08/2023]
Abstract
Centromeres are highly specialised chromosome domains defined by the presence of an epigenetic mark, the specific histone H3 variant called CENP-A (centromere protein A). They constitute the genomic regions on which kinetochores form and when defective cause segregation defects that can lead to aneuploidy and cancer. Here, we discuss how CENP-A is established and maintained to propagate centromere identity while subjected to dynamic chromatin remodelling during essential cellular processes like DNA repair, replication, and transcription. We highlight parallels and identify conserved mechanisms between different model organism with a particular focus on 1) the establishment of CENP-A at centromeres, 2) CENP-A maintenance during transcription and replication, and 3) the mechanisms that help preventing CENP-A localization at non-centromeric sites. We then give examples of how timely loading of new CENP-A to the centromere, maintenance of old CENP-A during S-phase and transcription, and removal of CENP-A at non-centromeric sites are coordinated and controlled by an intricate network of factors whose identity is slowly being unravelled.
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6
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Barbosa AC, Xu Z, Karari K, Williams W, Hauf S, Brown WRA. Mutation and selection explain why many eukaryotic centromeric DNA sequences are often A + T rich. Nucleic Acids Res 2021; 50:579-596. [PMID: 34928384 PMCID: PMC8754631 DOI: 10.1093/nar/gkab1219] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2021] [Revised: 11/16/2021] [Accepted: 11/30/2021] [Indexed: 01/10/2023] Open
Abstract
We have used chromosome engineering to replace native centromeric DNA with different test sequences at native centromeres in two different strains of the fission yeast Schizosaccharomyces pombe and have discovered that A + T rich DNA, whether synthetic or of bacterial origin, will function as a centromere in this species. Using genome size as a surrogate for the inverse of effective population size (Ne) we also show that the relative A + T content of centromeric DNA scales with Ne across 43 animal, fungal and yeast (Opisthokonta) species. This suggests that in most of these species the A + T content of the centromeric DNA is determined by a balance between selection and mutation. Combining the experimental results and the evolutionary analyses allows us to conclude that A + T rich DNA of almost any sequence will function as a centromere in most Opisthokonta species. The fact that many G/C to A/T substitutions are unlikely to be selected against may contribute to the rapid evolution of centromeric DNA. We also show that a neo-centromere sequence is not simply a weak version of native centromeric DNA and suggest that neo-centromeres require factors either for their propagation or establishment in addition to those required by native centromeres.
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Affiliation(s)
- Anne C Barbosa
- School of Life Sciences, University of Nottingham, Queen's Medical Centre, NG7 2UH, UK
| | - Zhengyao Xu
- School of Life Sciences, University of Nottingham, Queen's Medical Centre, NG7 2UH, UK
| | - Kazhal Karari
- School of Life Sciences, University of Nottingham, Queen's Medical Centre, NG7 2UH, UK
| | - Wendi Williams
- Virginia Tech, Department of Biological Sciences, Fralin Life Sciences Institute, 1015 Life Science Circle, Blacksburg, VA 24061, USA
| | - Silke Hauf
- Virginia Tech, Department of Biological Sciences, Fralin Life Sciences Institute, 1015 Life Science Circle, Blacksburg, VA 24061, USA
| | - William R A Brown
- School of Life Sciences, University of Nottingham, Queen's Medical Centre, NG7 2UH, UK
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7
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Dong Q, Yang J, Gao J, Li F. Recent insights into mechanisms preventing ectopic centromere formation. Open Biol 2021; 11:210189. [PMID: 34493071 PMCID: PMC8424319 DOI: 10.1098/rsob.210189] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
The centromere is a specialized chromosomal structure essential for chromosome segregation. Centromere dysfunction leads to chromosome segregation errors and genome instability. In most eukaryotes, centromere identity is specified epigenetically by CENP-A, a centromere-specific histone H3 variant. CENP-A replaces histone H3 in centromeres, and nucleates the assembly of the kinetochore complex. Mislocalization of CENP-A to non-centromeric regions causes ectopic assembly of CENP-A chromatin, which has a devastating impact on chromosome segregation and has been linked to a variety of human cancers. How non-centromeric regions are protected from CENP-A misincorporation in normal cells is largely unexplored. Here, we review the most recent advances on the mechanisms underlying the prevention of ectopic centromere formation, and discuss the implications in human disease.
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Affiliation(s)
- Qianhua Dong
- Department of Biology, New York University, New York, NY 10003-6688, USA
| | - Jinpu Yang
- Department of Biology, New York University, New York, NY 10003-6688, USA
| | - Jinxin Gao
- Department of Biology, New York University, New York, NY 10003-6688, USA
| | - Fei Li
- Department of Biology, New York University, New York, NY 10003-6688, USA
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8
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N-Terminus Does Not Govern Protein Turnover of Schizosaccharomyces pombe CENP-A. Int J Mol Sci 2020; 21:ijms21176175. [PMID: 32859127 PMCID: PMC7503380 DOI: 10.3390/ijms21176175] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Revised: 08/18/2020] [Accepted: 08/21/2020] [Indexed: 12/15/2022] Open
Abstract
Centromere integrity underlies an essential framework for precise chromosome segregation and epigenetic inheritance. Although centromeric DNA sequences vary among different organisms, all eukaryotic centromeres comprise a centromere-specific histone H3 variant, centromeric protein A (CENP-A), on which other centromeric proteins assemble into the kinetochore complex. This complex connects chromosomes to mitotic spindle microtubules to ensure accurate partitioning of the genome into daughter cells. Overexpression of CENP-A is associated with many cancers and is correlated with its mistargeting, forming extra-centromeric kinetochore structures. The mislocalization of CENP-A can be counteracted by proteolysis. The amino (N)-terminal domain (NTD) of CENP-A has been implicated in this regulation and shown to be dependent on the proline residues within this domain in Saccharomyces cerevisiae CENP-A, Cse4. We recently identified a proline-rich GRANT motif in the NTD of Schizosaccharomyces pombe CENP-A (SpCENP-A) that regulates the centromeric targeting of CENP-A via binding to the CENP-A chaperone Sim3. Here, we investigated whether the NTD is required to confer SpCENP-A turnover (i.e., counter stability) using various truncation mutants of SpCENP-A. We show that sequential truncation of the NTD did not improve the stability of the protein, indicating that the NTD of SpCENP-A does not drive turnover of the protein. Instead, we reproduced previous observations that heterochromatin integrity is important for SpCENP-A stability, and showed that this occurs in an NTD-independent manner. Cells bearing the null mutant of the histone H3 lysine 9 methyltransferase Clr4 (Δclr4), which have compromised constitutive heterochromatin integrity, showed reductions in the proportion of SpCENP-A in the chromatin-containing insoluble fraction of the cell extract, suggesting that heterochromatin may promote SpCENP-A chromatin incorporation. Thus, a disruption in heterochromatin may result in the delocalization of SpCENP-A from chromatin, thus exposing it to protein turnover. Taken together, we show that the NTD is not required to confer SpCENP-A protein turnover.
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9
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Hori T, Fukagawa T. Artificial generation of centromeres and kinetochores to understand their structure and function. Exp Cell Res 2020; 389:111898. [PMID: 32035949 DOI: 10.1016/j.yexcr.2020.111898] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Revised: 01/18/2020] [Accepted: 02/05/2020] [Indexed: 01/19/2023]
Abstract
The centromere is an essential genomic region that provides the surface to form the kinetochore, which binds to the spindle microtubes to mediate chromosome segregation during mitosis and meiosis. Centromeres of most organisms possess highly repetitive sequences, making it difficult to study these loci. However, an unusual centromere called a "neocentromere," which does not contain repetitive sequences, was discovered in a patient and can be generated experimentally. Recent advances in genome biology techniques allow us to analyze centromeric chromatin using neocentromeres. In addition to neocentromeres, artificial kinetochores have been generated on non-centromeric loci, using protein tethering systems. These are powerful tools to understand the mechanism of the centromere specification and kinetochore assembly. In this review, we introduce recent studies utilizing the neocentromeres and artificial kinetochores and discuss current problems in centromere biology.
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Affiliation(s)
- Tetsuya Hori
- Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka, 565-0871, Japan.
| | - Tatsuo Fukagawa
- Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka, 565-0871, Japan.
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10
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Nishimura K, Komiya M, Hori T, Itoh T, Fukagawa T. 3D genomic architecture reveals that neocentromeres associate with heterochromatin regions. J Cell Biol 2018; 218:134-149. [PMID: 30396998 PMCID: PMC6314543 DOI: 10.1083/jcb.201805003] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2018] [Revised: 09/21/2018] [Accepted: 10/15/2018] [Indexed: 12/22/2022] Open
Abstract
Although centromeres usually associate with heterochromatic repetitive sequences, such repetitive sequences are not detected around neocentromeres. Nishimura et al. performed systematic 4C analysis of cells containing differently positioned neocentromeres and demonstrate that these neocentromeres commonly associate with distant heterochromatin-rich regions at the 3D level. The centromere is an important genomic locus for chromosomal segregation. Although the centromere is specified by sequence-independent epigenetic mechanisms in most organisms, it is usually composed of highly repetitive sequences, which associate with heterochromatin. We have previously generated various chicken DT40 cell lines containing differently positioned neocentromeres, which do not contain repetitive sequences and do not associate with heterochromatin. In this study, we performed systematic 4C analysis using three cell lines containing differently positioned neocentromeres to identify neocentromere-associated regions at the 3D level. This analysis reveals that these neocentromeres commonly associate with specific heterochromatin-rich regions, which were distantly located from neocentromeres. In addition, we demonstrate that centromeric chromatin adopts a compact structure, and centromere clustering also occurs in vertebrate interphase nuclei. Interestingly, the occurrence of centromere–heterochromatin associations depend on CENP-H, but not CENP-C. Our analyses provide an insight into understanding the 3D architecture of the genome, including the centromeres.
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Affiliation(s)
- Kohei Nishimura
- Graduate School of Frontier Biosciences, Osaka University, Osaka, Japan
| | - Masataka Komiya
- Department of Biological Information, Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, Tokyo, Japan
| | - Tetsuya Hori
- Graduate School of Frontier Biosciences, Osaka University, Osaka, Japan
| | - Takehiko Itoh
- Department of Biological Information, Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, Tokyo, Japan
| | - Tatsuo Fukagawa
- Graduate School of Frontier Biosciences, Osaka University, Osaka, Japan
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11
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Fission Yeast CENP-C (Cnp3) Plays a Role in Restricting the Site of CENP-A Accumulation. G3-GENES GENOMES GENETICS 2018; 8:2723-2733. [PMID: 29925533 PMCID: PMC6071599 DOI: 10.1534/g3.118.200486] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The centromere is a chromosomal locus where a microtubule attachment site, termed kinetochore, is assembled in mitosis. In most eukaryotes, with the exception of holocentric species, each chromosome contains a single distinct centromere. A chromosome with an additional centromere undergoes successive rounds of anaphase bridge formation and breakage, or triggers a cell cycle arrest imposed by DNA damage and replication checkpoints. We report here a study in Schizosaccharomyces pombe to characterize a mutant (cnp3-1) in a gene encoding a homolog of mammalian centromere-specific protein, CENP-C. At the restrictive temperature 36°, the Cnp3-1 mutant protein loses its localization at the centromere. In the cnp3-1 mutant, the level of the Cnp1 (a homolog of a centromere-specific histone CENP-A) also decreases at the centromere. Interestingly, the cnp3-1 mutant is prone to promiscuous accumulation of Cnp1 at non-centromeric regions, when Cnp1 is present in excess. Unlike the wild type protein, Cnp3-1 mutant protein is found at the sites of promiscuous accumulation of Cnp1, suggesting that Cnp3-1 may stabilize or promote accumulation of Cnp1 at non-centromeric regions. From these results, we infer the role of Cnp3 in restricting the site of accumulation of Cnp1 and thus to prevent formation of de novo centromeres.
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12
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The Ino80 complex mediates epigenetic centromere propagation via active removal of histone H3. Nat Commun 2017; 8:529. [PMID: 28904333 PMCID: PMC5597579 DOI: 10.1038/s41467-017-00704-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Accepted: 07/19/2017] [Indexed: 12/25/2022] Open
Abstract
The centromere is the chromosomal locus at which the kinetochore is assembled to direct chromosome segregation. The histone H3 variant, centromere protein A (CENP-A), is known to epigenetically mark active centromeres, but the mechanism by which CENP-A propagates at the centromere, replacing histone H3, remains poorly understood. Using fission yeast, here we show that the Ino80 adenosine triphosphate (ATP)-dependent chromatin-remodeling complex, which removes histone H3-containing nucleosomes from associated chromatin, promotes CENP-ACnp1 chromatin assembly at the centromere in a redundant manner with another chromatin-remodeling factor Chd1Hrp1. CENP-ACnp1 chromatin actively recruits the Ino80 complex to centromeres to elicit eviction of histone H3-containing nucleosomes. Artificial targeting of Ino80 subunits to a non-centromeric DNA sequence placed in a native centromere enhances the spreading of CENP-ACnp1 chromatin into the non-centromeric DNA. Based on these results, we propose that CENP-ACnp1 chromatin employs the Ino80 complex to mediate the replacement of histone H3 with CENP-ACnp1, and thereby reinforces itself. The histone variant CENP-A marks active centromeres and replaces H3 at centromeres through a poorly understood mechanism. Here, the authors provide evidence that the chromatin remodeller Ino80 promotes CENP-A chromatin assembly at the centromere in fission yeast.
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13
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Burrack LS, Hutton HF, Matter KJ, Clancey SA, Liachko I, Plemmons AE, Saha A, Power EA, Turman B, Thevandavakkam MA, Ay F, Dunham MJ, Berman J. Neocentromeres Provide Chromosome Segregation Accuracy and Centromere Clustering to Multiple Loci along a Candida albicans Chromosome. PLoS Genet 2016; 12:e1006317. [PMID: 27662467 PMCID: PMC5035033 DOI: 10.1371/journal.pgen.1006317] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Accepted: 08/23/2016] [Indexed: 02/07/2023] Open
Abstract
Assembly of kinetochore complexes, involving greater than one hundred proteins, is essential for chromosome segregation and genome stability. Neocentromeres, or new centromeres, occur when kinetochores assemble de novo, at DNA loci not previously associated with kinetochore proteins, and they restore chromosome segregation to chromosomes lacking a functional centromere. Neocentromeres have been observed in a number of diseases and may play an evolutionary role in adaptation or speciation. However, the consequences of neocentromere formation on chromosome missegregation rates, gene expression, and three-dimensional (3D) nuclear structure are not well understood. Here, we used Candida albicans, an organism with small, epigenetically-inherited centromeres, as a model system to study the functions of twenty different neocentromere loci along a single chromosome, chromosome 5. Comparison of neocentromere properties relative to native centromere functions revealed that all twenty neocentromeres mediated chromosome segregation, albeit to different degrees. Some neocentromeres also caused reduced levels of transcription from genes found within the neocentromere region. Furthermore, like native centromeres, neocentromeres clustered in 3D with active/functional centromeres, indicating that formation of a new centromere mediates the reorganization of 3D nuclear architecture. This demonstrates that centromere clustering depends on epigenetically defined function and not on the primary DNA sequence, and that neocentromere function is independent of its distance from the native centromere position. Together, the results show that a neocentromere can form at many loci along a chromosome and can support the assembly of a functional kinetochore that exhibits native centromere functions including chromosome segregation accuracy and centromere clustering within the nucleus. The accurate segregation of chromosomes during cell division is essential for maintaining genome integrity. The centromere is the DNA region on each chromosome where assembly of a large protein complex, the kinetochore, is required to maintain proper chromosome segregation. In addition, active centromeres exhibit a specific three-dimensional organization within the nucleus: the centromeres associate with one another in a clustered manner. Neocentromeres, or new centromeres, appear at new places along the chromosome when a native centromere becomes non-functional. We used a yeast model, Candida albicans, and isolated twenty instances in which neocentromeres had formed at different positions. All of these neocentromeres were able to direct chromosome segregation, but some had increased error rates. Like native centromeres, these neocentromeres cluster in the nucleus with the other active centromeres. This implies that formation of a neocentromere leads to reorganization of the three-dimensional structure of the nucleus so that different regions of the chromosome are in closer contact to regions of other chromosomes. Recent work suggests that approximately 3% of cancers may contain chromosomes with neocentromeres. Our observations that many neocentromeres have increased error rates provides insight into genome instability in cancer cells. Changes in chromosome copy number may benefit the cancer cells by increasing numbers of oncogenes and/or drug resistance genes, but may also sensitize the cells to chemotherapy approaches that target chromosome segregation mechanisms.
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Affiliation(s)
- Laura S. Burrack
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, Minnesota, United States of America
- Department of Biology, Grinnell College, Grinnell, Iowa, United States of America
- Department of Biology, Gustavus Adolphus College, Saint Peter, Minnesota, United States of America
- * E-mail: (LSB); (JB)
| | - Hannah F. Hutton
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Kathleen J. Matter
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Shelly Applen Clancey
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Ivan Liachko
- Department of Genome Sciences, University of Washington, Seattle, Washington, United States of America
| | | | - Amrita Saha
- Department of Biology, Grinnell College, Grinnell, Iowa, United States of America
| | - Erica A. Power
- Department of Biology, Gustavus Adolphus College, Saint Peter, Minnesota, United States of America
| | - Breanna Turman
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, Minnesota, United States of America
| | | | - Ferhat Ay
- La Jolla Institute for Allergy and Immunology, La Jolla, California, United States of America
| | - Maitreya J. Dunham
- Department of Genome Sciences, University of Washington, Seattle, Washington, United States of America
| | - Judith Berman
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, Minnesota, United States of America
- Department of Microbiology and Biotechnology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Ramat Aviv, Israel
- * E-mail: (LSB); (JB)
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14
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Ccp1 Homodimer Mediates Chromatin Integrity by Antagonizing CENP-A Loading. Mol Cell 2016; 64:79-91. [PMID: 27666591 DOI: 10.1016/j.molcel.2016.08.022] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Revised: 05/24/2016] [Accepted: 08/16/2016] [Indexed: 12/26/2022]
Abstract
CENP-A is a centromere-specific histone 3 variant essential for centromere specification. CENP-A partially replaces canonical histone H3 at the centromeres. How the particular CENP-A/H3 ratio at centromeres is precisely maintained is unknown. It also remains unclear how CENP-A is excluded from non-centromeric chromatin. Here, we identify Ccp1, an uncharacterized NAP family protein in fission yeast that antagonizes CENP-A loading at both centromeric and non-centromeric regions. Like the CENP-A loading factor HJURP, Ccp1 interacts with CENP-A and is recruited to centromeres at the end of mitosis in a Mis16-dependent manner. These data indicate that factors with opposing CENP-A loading activities are recruited to centromeres. Furthermore, Ccp1 also cooperates with H2A.Z to evict CENP-A assembled in euchromatin. Structural analyses indicate that Ccp1 forms a homodimer that is required for its anti-CENP-A loading activity. Our study establishes mechanisms for maintenance of CENP-A homeostasis at centromeres and the prevention of ectopic assembly of centromeres.
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15
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Hildebrand EM, Biggins S. Regulation of Budding Yeast CENP-A levels Prevents Misincorporation at Promoter Nucleosomes and Transcriptional Defects. PLoS Genet 2016; 12:e1005930. [PMID: 26982580 PMCID: PMC4794243 DOI: 10.1371/journal.pgen.1005930] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2015] [Accepted: 02/22/2016] [Indexed: 01/08/2023] Open
Abstract
The exclusive localization of the histone H3 variant CENP-A to centromeres is essential for accurate chromosome segregation. Ubiquitin-mediated proteolysis helps to ensure that CENP-A does not mislocalize to euchromatin, which can lead to genomic instability. Consistent with this, overexpression of the budding yeast CENP-ACse4 is lethal in cells lacking Psh1, the E3 ubiquitin ligase that targets CENP-ACse4 for degradation. To identify additional mechanisms that prevent CENP-ACse4 misincorporation and lethality, we analyzed the genome-wide mislocalization pattern of overexpressed CENP-ACse4 in the presence and absence of Psh1 by chromatin immunoprecipitation followed by high throughput sequencing. We found that ectopic CENP-ACse4 is enriched at promoters that contain histone H2A.ZHtz1 nucleosomes, but that H2A.ZHtz1 is not required for CENP-ACse4 mislocalization. Instead, the INO80 complex, which removes H2A.ZHtz1 from nucleosomes, promotes the ectopic deposition of CENP-ACse4. Transcriptional profiling revealed gene expression changes in the psh1Δ cells overexpressing CENP-ACse4. The down-regulated genes are enriched for CENP-ACse4 mislocalization to promoters, while the up-regulated genes correlate with those that are also transcriptionally up-regulated in an htz1Δ strain. Together, these data show that regulating centromeric nucleosome localization is not only critical for maintaining centromere function, but also for ensuring accurate promoter function and transcriptional regulation. Chromosomes carry the genetic material in cells. When cells divide, each daughter cell must inherit a single copy of each chromosome. The centromere is the locus on each chromosome that ensures the equal distribution of chromosomes during cell division. One essential protein involved in this task is CENP-ACse4, which normally localizes exclusively to centromeres. Here, we investigated where CENP-ACse4 spreads in the genome when parts of its regulatory machinery are removed. We found that CENP-ACse4 becomes mislocalized to promoters, the region upstream of each gene that controls the activity of the gene. Consistent with this, the mislocalization of CENP-ACse4 to promoters leads to problems with gene activity. Our work shows that mislocalization of centromeric proteins can have effects beyond chromosome segregation defects, such as interfering with gene expression on chromosome arms.
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Affiliation(s)
- Erica M. Hildebrand
- Howard Hughes Medical Institute, Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
- Molecular and Cellular Biology Program, University of Washington, Seattle, Washington, United States of America
| | - Sue Biggins
- Howard Hughes Medical Institute, Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
- * E-mail:
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16
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Shugoshin forms a specialized chromatin domain at subtelomeres that regulates transcription and replication timing. Nat Commun 2016; 7:10393. [PMID: 26804021 PMCID: PMC4737732 DOI: 10.1038/ncomms10393] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2015] [Accepted: 12/07/2015] [Indexed: 01/11/2023] Open
Abstract
A chromosome is composed of structurally and functionally distinct domains. However, the molecular mechanisms underlying the formation of chromatin structure and the function of subtelomeres, the telomere-adjacent regions, remain obscure. Here we report the roles of the conserved centromeric protein Shugoshin 2 (Sgo2) in defining chromatin structure and functions of the subtelomeres in the fission yeast Schizosaccharomyces pombe. We show that Sgo2 localizes at the subtelomeres preferentially during G2 phase and is essential for the formation of a highly condensed subtelomeric chromatin body 'knob'. Furthermore, the absence of Sgo2 leads to the derepression of the subtelomeric genes and premature DNA replication at the subtelomeric late origins. Thus, the subtelomeric specialized chromatin domain organized by Sgo2 represses both transcription and replication to ensure proper gene expression and replication timing.
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17
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Escape from Mitotic Arrest: An Unexpected Connection Between Microtubule Dynamics and Epigenetic Regulation of Centromeric Chromatin in Schizosaccharomyces pombe. Genetics 2015; 201:1467-78. [PMID: 26510788 DOI: 10.1534/genetics.115.181792] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Accepted: 10/23/2015] [Indexed: 01/02/2023] Open
Abstract
Accurate chromosome segregation is necessary to ensure genomic integrity. Segregation depends on the proper functioning of the centromere, kinetochore, and mitotic spindle microtubules and is monitored by the spindle assembly checkpoint (SAC). In the fission yeast Schizosaccharomyces pombe, defects in Dis1, a microtubule-associated protein that influences microtubule dynamics, lead to mitotic arrest as a result of an active SAC and consequent failure to grow at low temperature. In a mutant dis1 background (dis1-288), loss of function of Msc1, a fission yeast homolog of the KDM5 family of proteins, suppresses the growth defect and promotes normal mitosis. Genetic analysis implicates a histone deacetylase (HDAC)-linked pathway in suppression because HDAC mutants clr6-1, clr3∆, and sir2∆, though not hos2∆, also promote normal mitosis in the dis1-288 mutant. Suppression of the dis phenotype through loss of msc1 function requires the spindle checkpoint protein Mad2 and is limited by the presence of the heterochromatin-associated HP1 protein homolog Swi6. We speculate that alterations in histone acetylation promote a centromeric chromatin environment that compensates for compromised dis1 function by allowing for successful kinetochore-microtubule interactions that can satisfy the SAC. In cells arrested in mitosis by mutation of dis1, loss of function of epigenetic determinants such as Msc1 or specific HDACs can promote cell survival. Because the KDM5 family of proteins has been implicated in human cancers, an appreciation of the potential role of this family of proteins in chromosome segregation is warranted.
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18
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Ohno Y, Ogiyama Y, Kubota Y, Kubo T, Ishii K. Acentric chromosome ends are prone to fusion with functional chromosome ends through a homology-directed rearrangement. Nucleic Acids Res 2015; 44:232-44. [PMID: 26433224 PMCID: PMC4705696 DOI: 10.1093/nar/gkv997] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2015] [Accepted: 09/23/2015] [Indexed: 01/19/2023] Open
Abstract
The centromeres of many eukaryotic chromosomes are established epigenetically on potentially variable tandem repeats; hence, these chromosomes are at risk of being acentric. We reported previously that artificially created acentric chromosomes in the fission yeast Schizosaccharomyces pombe can be rescued by end-to-end fusion with functional chromosomes. Here, we show that most acentric/functional chromosome fusion events in S. pombe cells harbouring an acentric chromosome I differed from the non-homologous end-joining-mediated rearrangements that result in deleterious dicentric fusions in normal cells, and were elicited by a previously unidentified homologous recombination (HR) event between chromosome end-associated sequences. The subtelomere repeats associated with the non-fusogenic ends were also destabilized in the surviving cells, suggesting a causal link between general subtelomere destabilization and acentric/functional chromosome fusion. A mutational analysis indicated that a non-canonical HR pathway was involved in the rearrangement. These findings are indicative of a latent mechanism that conditionally induces general subtelomere instability, presumably in the face of accidental centromere loss events, resulting in rescue of the fatal acentric chromosomes by interchromosomal HR.
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Affiliation(s)
- Yuko Ohno
- Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka 565-0871, Japan
| | - Yuki Ogiyama
- Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka 565-0871, Japan
| | - Yoshino Kubota
- Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka 565-0871, Japan
| | - Takuya Kubo
- Graduate School of Environmental Science, Hokkaido University, Sapporo, Hokkaido 060-0810, Japan
| | - Kojiro Ishii
- Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka 565-0871, Japan Institute for Academic Initiatives, Osaka University, Suita, Osaka 565-0871, Japan
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19
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Melters DP, Nye J, Zhao H, Dalal Y. Chromatin Dynamics in Vivo: A Game of Musical Chairs. Genes (Basel) 2015; 6:751-76. [PMID: 26262644 PMCID: PMC4584328 DOI: 10.3390/genes6030751] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Revised: 07/17/2015] [Accepted: 07/28/2015] [Indexed: 01/30/2023] Open
Abstract
Histones are a major component of chromatin, the nucleoprotein complex fundamental to regulating transcription, facilitating cell division, and maintaining genome integrity in almost all eukaryotes. In addition to canonical, replication-dependent histones, replication-independent histone variants exist in most eukaryotes. In recent years, steady progress has been made in understanding how histone variants assemble, their involvement in development, mitosis, transcription, and genome repair. In this review, we will focus on the localization of the major histone variants H3.3, CENP-A, H2A.Z, and macroH2A, as well as how these variants have evolved, their structural differences, and their functional significance in vivo.
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Affiliation(s)
- Daniël P Melters
- Chromatin Structure and Epigenetics Mechanisms Unit, Center for Cancer Research, National Cancer Institute, National Institutes of Health, 41 Library Drive, Bethesda, MD 20892, USA.
| | - Jonathan Nye
- Chromatin Structure and Epigenetics Mechanisms Unit, Center for Cancer Research, National Cancer Institute, National Institutes of Health, 41 Library Drive, Bethesda, MD 20892, USA.
| | - Haiqing Zhao
- Chromatin Structure and Epigenetics Mechanisms Unit, Center for Cancer Research, National Cancer Institute, National Institutes of Health, 41 Library Drive, Bethesda, MD 20892, USA.
- Biophysics Graduate Program, University of Maryland, College Park, MD 20742, USA.
| | - Yamini Dalal
- Chromatin Structure and Epigenetics Mechanisms Unit, Center for Cancer Research, National Cancer Institute, National Institutes of Health, 41 Library Drive, Bethesda, MD 20892, USA.
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20
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Chemical “Diversity” of Chromatin Through Histone Variants and Histone Modifications. ACTA ACUST UNITED AC 2015. [DOI: 10.1007/s40610-015-0005-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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21
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Affiliation(s)
- J Peter Svensson
- Department of Biosciences & Nutrition, Karolinska Institutet, Huddinge, Sweden
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22
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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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23
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Scott KC, Sullivan BA. Neocentromeres: a place for everything and everything in its place. Trends Genet 2013; 30:66-74. [PMID: 24342629 DOI: 10.1016/j.tig.2013.11.003] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2013] [Revised: 11/15/2013] [Accepted: 11/19/2013] [Indexed: 01/07/2023]
Abstract
Centromeres are essential for chromosome inheritance and genome stability. Centromeric proteins, including the centromeric histone centromere protein A (CENP-A), define the site of centromeric chromatin and kinetochore assembly. In many organisms, centromeres are located in or near regions of repetitive DNA. However, some atypical centromeres spontaneously form on unique sequences. These neocentromeres, or new centromeres, were first identified in humans, but have since been described in other organisms. Neocentromeres are functionally and structurally similar to endogenous centromeres, but lack the added complication of underlying repetitive sequences. Here, we discuss recent studies in chicken and fungal systems where genomic engineering can promote neocentromere formation. These studies reveal key genomic and epigenetic factors that support de novo centromere formation in eukaryotes.
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Affiliation(s)
- Kristin C Scott
- Institute for Genome Sciences & Policy, Duke University, DUMC 3382, Durham, NC 27708, USA; Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC 27710, USA; Division of Human Genetics, Duke University Medical Center, Durham, NC 27710, USA.
| | - Beth A Sullivan
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC 27710, USA; Division of Human Genetics, Duke University Medical Center, Durham, NC 27710, USA.
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