1
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Marshall WF, Fung JC. Modeling homologous chromosome recognition via nonspecific interactions. Proc Natl Acad Sci U S A 2024; 121:e2317373121. [PMID: 38722810 PMCID: PMC11098084 DOI: 10.1073/pnas.2317373121] [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: 10/06/2023] [Accepted: 03/18/2024] [Indexed: 05/18/2024] Open
Abstract
In many organisms, most notably Drosophila, homologous chromosomes associate in somatic cells, a phenomenon known as somatic pairing, which takes place without double strand breaks or strand invasion, thus requiring some other mechanism for homologs to recognize each other. Several studies have suggested a "specific button" model, in which a series of distinct regions in the genome, known as buttons, can associate with each other, mediated by different proteins that bind to these different regions. Here, we use computational modeling to evaluate an alternative "button barcode" model, in which there is only one type of recognition site or adhesion button, present in many copies in the genome, each of which can associate with any of the others with equal affinity. In this model, buttons are nonuniformly distributed, such that alignment of a chromosome with its correct homolog, compared with a nonhomolog, is energetically favored; since to achieve nonhomologous alignment, chromosomes would be required to mechanically deform in order to bring their buttons into mutual register. By simulating randomly generated nonuniform button distributions, many highly effective button barcodes can be easily found, some of which achieve virtually perfect pairing fidelity. This model is consistent with existing literature on the effect of translocations of different sizes on homolog pairing. We conclude that a button barcode model can attain highly specific homolog recognition, comparable to that seen in actual cells undergoing somatic homolog pairing, without the need for specific interactions. This model may have implications for how meiotic pairing is achieved.
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Affiliation(s)
- Wallace F. Marshall
- Department of Biochemistry and Biophysics, University of California, San Francisco, CA94158
| | - Jennifer C. Fung
- Department of Obstetrics, Gynecology and Reproductive Sciences, University of California, San Francisco, CA94158
- Center for Reproductive Sciences, University of California, San Francisco, CA94158
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2
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Liskovykh M, Petrov NS, Noskov VN, Masumoto H, Earnshaw WC, Schlessinger D, Shabalina SA, Larionov V, Kouprina N. Actively transcribed rDNA and distal junction (DJ) sequence are involved in association of NORs with nucleoli. Cell Mol Life Sci 2023; 80:121. [PMID: 37043028 PMCID: PMC10097779 DOI: 10.1007/s00018-023-04770-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 03/27/2023] [Accepted: 03/28/2023] [Indexed: 04/13/2023]
Abstract
Although they are organelles without a limiting membrane, nucleoli have an exclusive structure, built upon the rDNA-rich acrocentric short arms of five human chromosomes (nucleolar organizer regions or NORs). This has raised the question: what are the structural features of a chromosome required for its inclusion in a nucleolus? Previous work has suggested that sequences adjacent to the tandemly repeated rDNA repeat units (DJ, distal junction sequence) may be involved, and we have extended such studies by addressing several issues related to the requirements for the association of NORs with nucleoli. We exploited both a set of somatic cell hybrids containing individual human acrocentric chromosomes and a set of Human Artificial Chromosomes (HACs) carrying different parts of a NOR, including an rDNA unit or DJ or PJ (proximal junction) sequence. Association of NORs with nucleoli was increased when constituent rDNA was transcribed and may be also affected by the status of heterochromatin blocks formed next to the rDNA arrays. Furthermore, our data suggest that a relatively small size DJ region, highly conserved in evolution, is also involved, along with the rDNA repeats, in the localization of p-arms of acrocentric chromosomes in nucleoli. Thus, we infer a cooperative action of rDNA sequence-stimulated by its activity-and sequences distal to rDNA contributing to incorporation into nucleoli. Analysis of NOR sequences also identified LncRNA_038958 in the DJ, a candidate transcript with the region of the suggested promoter that is located close to the DJ/rDNA boundary and contains CTCF binding sites. This LncRNA may affect RNA Polymerase I and/or nucleolar activity. Our findings provide the basis for future studies to determine which RNAs and proteins interact critically with NOR sequences to organize the higher-order structure of nucleoli and their function in normal cells and pathological states.
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Affiliation(s)
- Mikhail Liskovykh
- Developmental Therapeutics Branch, National Cancer Institute, NIH, Bethesda, MD, 20892, USA.
| | - Nikolai S Petrov
- Developmental Therapeutics Branch, National Cancer Institute, NIH, Bethesda, MD, 20892, USA
| | - Vladimir N Noskov
- Developmental Therapeutics Branch, National Cancer Institute, NIH, Bethesda, MD, 20892, USA
| | - Hiroshi Masumoto
- Laboratory of Chromosome Engineering, Department of Frontier Research and Development, Kazusa DNA Research Institute, Kisarazu, Chiba, 292-0818, Japan
| | - William C Earnshaw
- Wellcome Centre for Cell Biology, University of Edinburgh, Edinburgh, EH9 3JR, Scotland, UK
| | - David Schlessinger
- National Institute on Aging, Laboratory of Genetics and Genomics, NIH, Baltimore, MD, 21224, USA
| | - Svetlana A Shabalina
- National Center for Biotechnology Information, National Library of Medicine, NIH, Bethesda, MD, 20892, USA
| | - Vladimir Larionov
- Developmental Therapeutics Branch, National Cancer Institute, NIH, Bethesda, MD, 20892, USA.
| | - Natalay Kouprina
- Developmental Therapeutics Branch, National Cancer Institute, NIH, Bethesda, MD, 20892, USA.
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3
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Wang L, Wu B, Ma Y, Ren Z, Li W. The blooming of an old story on the bouquet. Biol Reprod 2022; 107:289-300. [PMID: 35470849 DOI: 10.1093/biolre/ioac075] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2021] [Revised: 03/09/2022] [Accepted: 04/12/2022] [Indexed: 11/13/2022] Open
Abstract
As an evolutionarily conserved process, the bouquet stage during meiosis was discovered over a century ago, and active research on this important stage continues. Since the discovery of the first bouquet-related protein Taz1p in 1998, several bouquet formation-related proteins have been identified in various eukaryotes. These proteins are involved in the interaction between telomeres and the inner nuclear membrane (INM), and once these interactions are disrupted, meiotic progression is arrested, leading to infertility. Recent studies have provided significant insights into the relationships and interactions among bouquet formation-related proteins. In this review, we summarize the components involved in telomere-INM interactions and focus on their roles in bouquet formation and telomere homeostasis maintenance. In addition, we examined bouquet-related proteins in different species from an evolutionary viewpoint, highlighting the potential interactions among them.
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Affiliation(s)
- Lina Wang
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China.,Department of Respiratory, China National Clinical Research Center of Respiratory Diseases, Beijing Children's Hospital, Capital Medical University, National Center for Children's Health, Beijing 100045, China.,University of the Chinese Academy of Sciences, Beijing 100049, China
| | - Bingbing Wu
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China.,University of the Chinese Academy of Sciences, Beijing 100049, China
| | - Yanjie Ma
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China.,University of the Chinese Academy of Sciences, Beijing 100049, China
| | - Zhengxing Ren
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China.,University of the Chinese Academy of Sciences, Beijing 100049, China
| | - Wei Li
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China.,University of the Chinese Academy of Sciences, Beijing 100049, China.,Institute of Reproductive Health and Perinatology, Guangzhou Women and Children's Medical Center, Guangzhou Medical University, 510623 Guangzhou, China
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4
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Golczyk H, Limanówka A, Uchman-Książek A. Pericentromere clustering in Tradescantia section Rhoeo involves self-associations of AT- and GC-rich heterochromatin fractions, is developmentally regulated, and increases during differentiation. Chromosoma 2020; 129:227-242. [PMID: 32681184 PMCID: PMC7666280 DOI: 10.1007/s00412-020-00740-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Revised: 06/30/2020] [Accepted: 07/01/2020] [Indexed: 11/30/2022]
Abstract
A spectacular but poorly recognized nuclear repatterning is the association of heterochromatic domains during interphase. Using base-specific fluorescence and extended-depth-of-focus imaging, we show that the association of heterochromatic pericentromeres composed of AT- and GC-rich chromatin occurs on a large scale in cycling meiotic and somatic cells and during development in ring- and bivalent-forming Tradescantia spathacea (section Rhoeo) varieties. The mean number of pericentromere AT-rich domains per root meristem nucleus was ca. half the expected diploid number in both varieties, suggesting chromosome pairing via (peri)centromeric regions. Indeed, regular pairing of AT-rich domains was observed. The AT- and GC-rich associations in differentiated cells contributed to a significant reduction of the mean number of the corresponding foci per nucleus in relation to root meristem. Within the first 10 mm of the root, the pericentromere attraction was in progress, as if it was an active process and involved both AT- and GC-rich associations. Complying with Rabl arrangement, the pericentromeres preferentially located on one nuclear pole, clustered into diverse configurations. Among them, a strikingly regular one with 5-7 ring-arranged pericentromeric AT-rich domains may be potentially engaged in chromosome positioning during mitosis. The fluorescent pattern of pachytene meiocytes and somatic nuclei suggests the existence of a highly prescribed ring/chain type of chromocenter architecture with side-by-side arranged pericentromeric regions. The dynamics of pericentromere associations together with their non-random location within nuclei was compared with nuclear architecture in other organisms, including the widely explored Arabidopsis model.
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Affiliation(s)
- Hieronim Golczyk
- Department of Molecular Biology, Institute of Biological Sciences, John Paul II Catholic University of Lublin, Konstantynów 1i, 20-708, Lublin, Poland.
| | - Arleta Limanówka
- Department of Plant Cytology and Embryology, Institute of Botany, Jagiellonian University, Grodzka 52, 31-044, Cracow, Poland
| | - Anna Uchman-Książek
- Department of Plant Cytology and Embryology, Institute of Botany, Jagiellonian University, Grodzka 52, 31-044, Cracow, Poland
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5
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Ravi M, Ramanathan S, Krishna K. Factors, mechanisms and implications of chromatin condensation and chromosomal structural maintenance through the cell cycle. J Cell Physiol 2019; 235:758-775. [PMID: 31264212 DOI: 10.1002/jcp.29038] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Accepted: 06/12/2019] [Indexed: 12/16/2022]
Abstract
A series of well-orchestrated events help in the chromatin condensation and the formation of chromosomes. Apart from the formation of chromosomes, maintenance of their structure is important, especially for the cell division. The structural maintenance of chromosome (SMC) proteins, the non-SMC proteins and the SMC complexes are critical for the maintenance of chromosome structure. While condensins have roles for the DNA compaction, organization, and segregation, the cohesin functions in a cyclic manner through the cell cycle, as a "cohesin cycle." Specific mechanisms maintain the architecture of the centromere, the kinetochore and the telomeres which are in tandem with the cell cycle checkpoints. The presence of chromosomal territories and compactness differences through the length of the chromosomes might have implications on selective susceptibility of specific chromosomes for induced genotoxicity.
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Affiliation(s)
- Maddaly Ravi
- Department of Human Genetics, Faculty of Biomedical Sciences, Technology and Research, Sri Ramachandra Institute of Higher Education and Research, Porur, Chennai, India
| | - Srishti Ramanathan
- Department of Human Genetics, Faculty of Biomedical Sciences, Technology and Research, Sri Ramachandra Institute of Higher Education and Research, Porur, Chennai, India
| | - Krupa Krishna
- Department of Human Genetics, Faculty of Biomedical Sciences, Technology and Research, Sri Ramachandra Institute of Higher Education and Research, Porur, Chennai, India
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6
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Clarke DJ, Azuma Y. Non-Catalytic Roles of the Topoisomerase IIα C-Terminal Domain. Int J Mol Sci 2017; 18:ijms18112438. [PMID: 29149026 PMCID: PMC5713405 DOI: 10.3390/ijms18112438] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2017] [Revised: 11/10/2017] [Accepted: 11/14/2017] [Indexed: 12/26/2022] Open
Abstract
DNA Topoisomerase IIα (Topo IIα) is a ubiquitous enzyme in eukaryotes that performs the strand passage reaction where a double helix of DNA is passed through a second double helix. This unique reaction is critical for numerous cellular processes. However, the enzyme also possesses a C-terminal domain (CTD) that is largely dispensable for the strand passage reaction but is nevertheless important for the fidelity of cell division. Recent studies have expanded our understanding of the roles of the Topo IIα CTD, in particular in mitotic mechanisms where the CTD is modified by Small Ubiquitin-like Modifier (SUMO), which in turn provides binding sites for key regulators of mitosis.
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Affiliation(s)
- Duncan J Clarke
- Department of Genetics, Cell Biology & Development, University of Minnesota, 420 Washington Ave SE, Minneapolis, MN 55455, USA.
| | - Yoshiaki Azuma
- Department of Molecular Biosciences, University of Kansas, Lawrence, KS 66045, USA.
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7
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Matsuda A, Asakawa H, Haraguchi T, Hiraoka Y. Spatial organization of the Schizosaccharomyces pombe genome within the nucleus. Yeast 2016; 34:55-66. [PMID: 27766670 DOI: 10.1002/yea.3217] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2016] [Revised: 10/06/2016] [Accepted: 10/13/2016] [Indexed: 12/14/2022] Open
Abstract
The fission yeast Schizosaccharomyces pombe is a useful experimental system for studying the organization of chromosomes within the cell nucleus. S. pombe has a small genome that is organized into three chromosomes. The small size of the genome and the small number of chromosomes are advantageous for cytological and genome-wide studies of chromosomes; however, the small size of the nucleus impedes microscopic observations owing to limits in spatial resolution during imaging. Recent advances in microscopy, such as super-resolution microscopy, have greatly expanded the use of S. pombe as a model organism in a wide range of studies. In addition, biochemical studies, such as chromatin immunoprecipitation and chromosome conformation capture, have provided complementary approaches. Here, we review the spatial organization of the S. pombe genome as determined by a combination of cytological and biochemical studies. Copyright © 2016 John Wiley & Sons, Ltd.
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Affiliation(s)
- Atsushi Matsuda
- Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, 565-0871, Japan.,Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology, 588-2 Iwaoka, Iwaoka-cho, Nishi-ku, Kobe, 651-2492, Japan
| | - Haruhiko Asakawa
- Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, 565-0871, Japan
| | - Tokuko Haraguchi
- Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, 565-0871, Japan.,Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology, 588-2 Iwaoka, Iwaoka-cho, Nishi-ku, Kobe, 651-2492, Japan
| | - Yasushi Hiraoka
- Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, 565-0871, Japan.,Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology, 588-2 Iwaoka, Iwaoka-cho, Nishi-ku, Kobe, 651-2492, Japan
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8
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Maslova A, Zlotina A, Kosyakova N, Sidorova M, Krasikova A. Three-dimensional architecture of tandem repeats in chicken interphase nucleus. Chromosome Res 2016; 23:625-39. [PMID: 26316311 DOI: 10.1007/s10577-015-9485-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Tandem repeats belong to a class of genomic repetitive elements that form arrays of head-to-tail monomers. Due to technical difficulties in sequencing and assembly of large tandem repeat arrays, it remains largely unknown by which mechanisms tandem-repeat-containing regions aid in maintenance of ordered radial genome organization during interphase. Here we analyzed spatial distribution of several types of tandem repeats in interphase nuclei of chicken MDCC-MSB1 cells and somatic tissues relative to heterochromatin compartments and nuclear center. We showed that telomere and subtelomere repeats generally localize at the nuclear or chromocenters periphery. A tandem repeat known as CNM, typical for centromere regions of gene-dense microchromosomes, forms interchromosome clusters and occupies DAPI-positive chromocenters that appear predominantly within the nuclear interior. In contrast, centromere-specific tandem repeats of the majority of gene-poor macrochromosomes are embedded into the peripheral layer of heterochromatin. Chicken chromocenters rarely comprise centromere sequences of both macro- and microchromosomes, whose territories localize in different radial nuclear zones. Possible mechanisms of observed tandem repeats positioning and its implication in highly ordered arrangement of chromosome territories in chicken interphase nucleus are discussed.
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Affiliation(s)
- Antonina Maslova
- Saint Petersburg State University, Saint Petersburg, 198504, Russia
| | - Anna Zlotina
- Saint Petersburg State University, Saint Petersburg, 198504, Russia
| | - Nadezhda Kosyakova
- Institute of Human Genetics, Jena University Hospital, Friedrich Schiller University, Jena, Germany
| | - Marina Sidorova
- Saint Petersburg State University, Saint Petersburg, 198504, Russia
| | - Alla Krasikova
- Saint Petersburg State University, Saint Petersburg, 198504, Russia.
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9
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Pochukalina GN, Ilicheva NV, Podgornaya OI, Voronin AP. Nucleolus-like body of mouse oocytes contains lamin A and B and TRF2 but not actin and topo II. Mol Cytogenet 2016; 9:50. [PMID: 27347007 PMCID: PMC4921027 DOI: 10.1186/s13039-016-0259-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Accepted: 06/18/2016] [Indexed: 01/06/2023] Open
Abstract
BACKGROUND During the final stages of oocyte development, all chromosomes join in a limited nuclear volume for the final formation of a single complex chromatin structure - the karyosphere. In the majority of mammalian species, the chromosomes surround a round protein/fibrillar body known as the central body, or nucleolus-like body (NLB). Nothing seems to unite the inner portion of the karyosphere with the nucleolus except position at its remnants. Nevertheless, in this study we will use term NLB as the conventional one for karyosphere with the central body. At the morphological level, NLBs consist of tightly-packed fibres of 6-10 nm. The biochemical structure of this dense, compact NLB fibre centre remains uncertain. RESULTS The aim of this study was to determine which proteins represent the NLB components at final stages of karyosphere formation in mouse oogenesis. To determine this, three antibodies (ABs) have been examined against different actin epitopes. Examination of both ABs against the actin N-end provided similar results: spots inside the nucleus. Double staining with AB against SC35 and actin revealed the colocalization of these proteins in IGCs (interchromatin granule clusters/nuclear speckles/SC35 domains). In contrast, examination of polyclonal AB against peptide at the C-end reveals a different result: actin is localized exclusively in connection with the chromatin. Surprisingly, no forms of actin or topoisomerase II are present as components of the NLB. It was discovered that: (1) lamin B is an NLB component from the beginning of NLB formation, and a major portion of it resides in the NLB at the end of oocyte development; (2) lamin A undergoes rapid movement into the NLB, and a majority of it remains in the NLB; (3) the telomere-binding protein TRF2 resides in the IGCs/nuclear speckles until the end of oocyte development, when significant part of it transfers to the NLB. CONCLUSIONS NLBs do not contain actin or topo II. Lamin B is involved from the beginning of NLB formation. Both Lamin A and TRF2 exhibit rapid movement to the NLB at the end of oogenesis. This dynamic distribution of proteins may reflect the NLB's role in future chromatin organization post-fertilisation.
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Affiliation(s)
| | - Nadya V. Ilicheva
- />Institute of Cytology, Russian Academy of Sciences, St Petersburg, 194064 Russia
| | - Olga I. Podgornaya
- />Institute of Cytology, Russian Academy of Sciences, St Petersburg, 194064 Russia
- />Saint Petersburg State University, St Petersburg, 199034 Russia
- />Far Eastern Federal University, Vladivostok, 690950 Russia
| | - Alexey P. Voronin
- />Institute of Cytology, Russian Academy of Sciences, St Petersburg, 194064 Russia
- />Saint Petersburg State University, St Petersburg, 199034 Russia
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10
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Schmid M, Guttenbach M, Steinlein C, Wanner G, Houben A. Cytogenetic Characterization of the TM4 Mouse Sertoli Cell Line. II. Chromosome Microdissection, FISH, Scanning Electron Microscopy, and Confocal Laser Scanning Microscopy. Cytogenet Genome Res 2016; 147:135-43. [DOI: 10.1159/000444157] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/16/2015] [Indexed: 11/19/2022] Open
Abstract
The chromosomes and interphase cell nuclei of the permanent mouse Sertoli cell line TM4 were examined by chromosome microdissection, FISH, scanning electron microscopy, and confocal laser scanning microscopy. The already known marker chromosomes m1-m5 were confirmed, and 2 new large marker chromosomes m6 and m7 were characterized. The minute heterochromatic marker chromosomes m4 and m5 were microdissected and their DNA amplified by DOP-PCR. FISH of this DNA probe on TM4 metaphase chromosomes demonstrated that the m4 and m5 marker chromosomes have derived from the centromeric regions of normal telocentric mouse chromosomes. Ectopic pairing of the m4 and m5 marker chromosomes with the centromeric region of any of the other chromosomes (centromeric associations) was apparent in ∼60% of the metaphases. Scanning electron microscopy revealed DNA-protein bridges connecting the centromeric regions of normal chromosomes and the associated m4 and m5 marker chromosomes. Interphase cell nuclei of TM4 Sertoli cells did not exhibit the characteristic morphology of Sertoli cells in the testes of adult mice as shown by fluorescence microscopy and confocal laser scanning microscopy.
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11
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Abstract
Nucleoli are formed on the basis of ribosomal genes coding for RNAs of ribosomal particles, but also include a great variety of other DNA regions. In this article, we discuss the characteristics of ribosomal DNA: the structure of the rDNA locus, complex organization and functions of the intergenic spacer, multiplicity of gene copies in one cell, selective silencing of genes and whole gene clusters, relation to components of nucleolar ultrastructure, specific problems associated with replication. We also review current data on the role of non-ribosomal DNA in the organization and function of nucleoli. Finally, we discuss probable causes preventing efficient visualization of DNA in nucleoli.
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12
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Kumar A, Mazzanti M, Mistrik M, Kosar M, Beznoussenko GV, Mironov AA, Garrè M, Parazzoli D, Shivashankar GV, Scita G, Bartek J, Foiani M. ATR mediates a checkpoint at the nuclear envelope in response to mechanical stress. Cell 2015; 158:633-46. [PMID: 25083873 PMCID: PMC4121522 DOI: 10.1016/j.cell.2014.05.046] [Citation(s) in RCA: 155] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2013] [Revised: 04/14/2014] [Accepted: 05/28/2014] [Indexed: 11/16/2022]
Abstract
ATR controls chromosome integrity and chromatin dynamics. We have previously shown that yeast Mec1/ATR promotes chromatin detachment from the nuclear envelope to counteract aberrant topological transitions during DNA replication. Here, we provide evidence that ATR activity at the nuclear envelope responds to mechanical stress. Human ATR associates with the nuclear envelope during S phase and prophase, and both osmotic stress and mechanical stretching relocalize ATR to nuclear membranes throughout the cell cycle. The ATR-mediated mechanical response occurs within the range of physiological forces, is reversible, and is independent of DNA damage signaling. ATR-defective cells exhibit aberrant chromatin condensation and nuclear envelope breakdown. We propose that mechanical forces derived from chromosome dynamics and torsional stress on nuclear membranes activate ATR to modulate nuclear envelope plasticity and chromatin association to the nuclear envelope, thus enabling cells to cope with the mechanical strain imposed by these molecular processes. ATR localizes at the nuclear envelope in S phase and prophase ATR responds to mechanical stress by relocalizing to the nuclear envelope The ATR mechanical response is fast and reversible ATR coordinates chromatin condensation and nuclear envelope breakdown
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Affiliation(s)
- Amit Kumar
- Fondazione Istituto FIRC di Oncologia Molecolare (IFOM), Via Adamello 16, 20139 Milan, Italy
| | | | - Martin Mistrik
- Institute of Molecular and Translational Medicine, Faculty of Medicine and Dentistry, Palacky University, 77115 Olomouc, Czech Republic
| | - Martin Kosar
- Danish Cancer Society Research Center, 2100 Copenhagen, Denmark; Institute of Molecular Genetics, v.v.i., Academy of Sciences of the Czech Republic, 14220 Prague, Czech Republic
| | - Galina V Beznoussenko
- Fondazione Istituto FIRC di Oncologia Molecolare (IFOM), Via Adamello 16, 20139 Milan, Italy
| | - Alexandre A Mironov
- Fondazione Istituto FIRC di Oncologia Molecolare (IFOM), Via Adamello 16, 20139 Milan, Italy
| | - Massimiliano Garrè
- Fondazione Istituto FIRC di Oncologia Molecolare (IFOM), Via Adamello 16, 20139 Milan, Italy
| | - Dario Parazzoli
- Fondazione Istituto FIRC di Oncologia Molecolare (IFOM), Via Adamello 16, 20139 Milan, Italy
| | - G V Shivashankar
- Mechanobiology Institute and Department of Biological Sciences, National University of Singapore, 117411 Singapore, Singapore
| | - Giorgio Scita
- Fondazione Istituto FIRC di Oncologia Molecolare (IFOM), Via Adamello 16, 20139 Milan, Italy; Università degli Studi di Milano, 20122 Milan, Italy
| | - Jiri Bartek
- Institute of Molecular and Translational Medicine, Faculty of Medicine and Dentistry, Palacky University, 77115 Olomouc, Czech Republic; Danish Cancer Society Research Center, 2100 Copenhagen, Denmark; Institute of Molecular Genetics, v.v.i., Academy of Sciences of the Czech Republic, 14220 Prague, Czech Republic.
| | - Marco Foiani
- Fondazione Istituto FIRC di Oncologia Molecolare (IFOM), Via Adamello 16, 20139 Milan, Italy; Università degli Studi di Milano, 20122 Milan, Italy.
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13
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Mandrioli M, Bandinelli S, Manicardi GC. Occurrence of Rabl-like telomere clustering in the holocentric chromosomes of the peach potato aphid Myzus persicae (Hemiptera; Aphididae). Cytogenet Genome Res 2014; 144:68-75. [PMID: 25277538 DOI: 10.1159/000366049] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/12/2014] [Indexed: 11/19/2022] Open
Abstract
Several studies demonstrated that chromosome anchoring to nuclear structures is involved in the organization of the interphase nucleus. The Rabl configuration, a well-studied chromosome organization in the interphase nucleus, has been deeply studied in organisms with monocentric chromosomes but just slightly touched in species with holocentric chromosomes. In the present paper, by means of the isolation and chromosomal mapping of the C0t DNA fraction and chromatin immunoprecipitation with anti-LEM-2 antibodies, we evidenced the presence of few foci where telomeres and subtelomeric regions cluster in the aphid interphase nuclei, suggesting the occurrence of a Rabl-like chromosome configuration. The same experimental approaches also evidenced that most of the repetitive DNA of the 2 X chromosomes is located at the periphery of the nucleus, whereas the ribosomal genes, located at 1 telomere of each X chromosome, are present towards the inner portion of the nucleus, favoring their transcriptional activity.
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Affiliation(s)
- Mauro Mandrioli
- Dipartimento di Scienze della Vita, Università di Modena e Reggio Emilia, Modena, Italy
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14
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Roles, and establishment, maintenance and erasing of the epigenetic cytosine methylation marks in plants. J Genet 2014; 92:629-66. [PMID: 24371187 DOI: 10.1007/s12041-013-0273-8] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Heritable information in plants consists of genomic information in DNA sequence and epigenetic information superimposed on DNA sequence. The latter is in the form of cytosine methylation at CG, CHG and CHH elements (where H = A, T orC) and a variety of histone modifications in nucleosomes. The epialleles arising from cytosine methylation marks on the nuclear genomic loci have better heritability than the epiallelic variation due to chromatin marks. Phenotypic variation is increased manifold by epiallele comprised methylomes. Plants (angiosperms) have highly conserved genetic mechanisms to establish, maintain or erase cytosine methylation from epialleles. The methylation marks in plants fluctuate according to the cell/tissue/organ in the vegetative and reproductive phases of plant life cycle. They also change according to environment. Epialleles arise by gain or loss of cytosine methylation marks on genes. The changes occur due to the imperfection of the processes that establish and maintain the marks and on account of spontaneous and stress imposed removal of marks. Cytosine methylation pattern acquired in response to abiotic or biotic stress is often inherited over one to several subsequent generations.Cytosine methylation marks affect physiological functions of plants via their effect(s) on gene expression levels. They also repress transposable elements that are abundantly present in plant genomes. The density of their distribution along chromosome lengths affects meiotic recombination rate, while their removal increases mutation rate. Transposon activation due to loss of methylation causes rearrangements such that new gene regulatory networks arise and genes for microRNAs may originate. Cytosine methylation dynamics contribute to evolutionary changes. This review presents and discusses the available evidence on origin, removal and roles of cytosine methylation and on related processes, such as RNA directed DNA methylation, imprinting, paramutation and transgenerational memory in plants.
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Wong X, Luperchio TR, Reddy KL. NET gains and losses: the role of changing nuclear envelope proteomes in genome regulation. Curr Opin Cell Biol 2014; 28:105-20. [PMID: 24886773 DOI: 10.1016/j.ceb.2014.04.005] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2014] [Revised: 03/21/2014] [Accepted: 04/11/2014] [Indexed: 01/13/2023]
Abstract
In recent years, our view of the nucleus has changed considerably with an increased awareness of the roles dynamic higher order chromatin structure and nuclear organization play in nuclear function. More recently, proteomics approaches have identified differential expression of nuclear lamina and nuclear envelope transmembrane (NET) proteins. Many NETs have been implicated in a range of developmental disorders as well as cell-type specific biological processes, including genome organization and nuclear morphology. While further studies are needed, it is clear that the differential nuclear envelope proteome contributes to cell-type specific nuclear identity and functions. This review discusses the importance of proteome diversity at the nuclear periphery and highlights the putative roles of NET proteins, with a focus on nuclear architecture.
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Affiliation(s)
- Xianrong Wong
- Johns Hopkins University, School of Medicine, Department of Biological Chemistry and Center for Epigenetics, 855N. Wolfe St., Rangos 574, Baltimore, MD 21044, United States
| | - Teresa R Luperchio
- Johns Hopkins University, School of Medicine, Department of Biological Chemistry and Center for Epigenetics, 855N. Wolfe St., Rangos 574, Baltimore, MD 21044, United States
| | - Karen L Reddy
- Johns Hopkins University, School of Medicine, Department of Biological Chemistry and Center for Epigenetics, 855N. Wolfe St., Rangos 574, Baltimore, MD 21044, United States.
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16
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Błaszczak Z, Kreysing M, Guck J. Direct observation of light focusing by single photoreceptor cell nuclei. OPTICS EXPRESS 2014; 22:11043-11060. [PMID: 24921803 DOI: 10.1364/oe.22.011043] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The vertebrate retina is inverted with respect to its optical function, which requires light to pass through the entire tissue prior to detection. The last significant barrier for photons to overcome is the outer nuclear layer formed by photoreceptor cell (PRC) nuclei. Here we experimentally characterise the optical properties of PRC nuclei using bright-field defocusing microscopy to capture near-field intensity distributions behind individual nuclei. We find that some nuclei efficiently focus incident light confirming earlier predictions based on comparative studies of chromatin organisation in nocturnal and diurnal mammals. The emergence of light focusing during the development of mouse nuclei highlights the acquired nature of the observed lens-like behaviour. Optical characterisation of these nuclei is an important first step towards an improved understanding of how light transmission through the retina is influenced by its constituents.
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Hemmer W, Morawetz W. Karyological Differentiation in Sapindaceae with Special Reference toSerjaniaandCardiospermum. ACTA ACUST UNITED AC 2014. [DOI: 10.1111/j.1438-8677.1990.tb00177.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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18
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Genome regulation at the peripheral zone: lamina associated domains in development and disease. Curr Opin Genet Dev 2014; 25:50-61. [PMID: 24556270 DOI: 10.1016/j.gde.2013.11.021] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2013] [Accepted: 11/29/2013] [Indexed: 12/18/2022]
Abstract
The nuclear periphery has been implicated in gene regulation and it has been proposed that proximity to the nuclear lamina and inner nuclear membrane (INM) leads to gene repression. More recently, it appears that there is a correlation and interdependence between lamina associated domains (LADs), the epigenome and overall three-dimensional architecture of the genome. However, the mechanisms of such organization at the 'peripheral zone' and the functional significance of these associations are poorly understood. The role these domains play in development and disease is an active and exciting area of research, expanding our knowledge of how the three-dimensional (3D) genome is regulated.
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19
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Quin JE, Devlin JR, Cameron D, Hannan KM, Pearson RB, Hannan RD. Targeting the nucleolus for cancer intervention. Biochim Biophys Acta Mol Basis Dis 2014; 1842:802-16. [PMID: 24389329 DOI: 10.1016/j.bbadis.2013.12.009] [Citation(s) in RCA: 173] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2013] [Accepted: 12/17/2013] [Indexed: 12/17/2022]
Abstract
The contribution of the nucleolus to cancer is well established with respect to its traditional role in facilitating ribosome biogenesis and proliferative capacity. More contemporary studies however, infer that nucleoli contribute a much broader role in malignant transformation. Specifically, extra-ribosomal functions of the nucleolus position it as a central integrator of cellular proliferation and stress signaling, and are emerging as important mechanisms for modulating how oncogenes and tumor suppressors operate in normal and malignant cells. The dependence of certain tumor cells to co-opt nucleolar processes to maintain their cancer phenotypes has now clearly been demonstrated by the application of small molecule inhibitors of RNA Polymerase I to block ribosomal DNA transcription and disrupt nucleolar function (Bywater et al., 2012 [1]). These drugs, which selectively kill tumor cells in vivo while sparing normal cells, have now progressed to clinical trials. It is likely that we have only just begun to scratch the surface of the potential of the nucleolus as a new target for cancer therapy, with "suppression of nucleolar stress" representing an emerging "hallmark" of cancer. This article is part of a Special Issue entitled: Role of the Nucleolus in Human Disease.
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Affiliation(s)
- Jaclyn E Quin
- Oncogenic Signalling and Growth Control Program, Peter MacCallum Cancer Centre, East Melbourne, Victoria, Australia; Department of Biochemistry and Molecular Biology, The University of Melbourne, Parkville, Victoria, Australia
| | - Jennifer R Devlin
- Oncogenic Signalling and Growth Control Program, Peter MacCallum Cancer Centre, East Melbourne, Victoria, Australia; Department of Biochemistry and Molecular Biology, The University of Melbourne, Parkville, Victoria, Australia
| | - Donald Cameron
- Oncogenic Signalling and Growth Control Program, Peter MacCallum Cancer Centre, East Melbourne, Victoria, Australia
| | - Kate M Hannan
- Oncogenic Signalling and Growth Control Program, Peter MacCallum Cancer Centre, East Melbourne, Victoria, Australia; Department of Biochemistry and Molecular Biology, The University of Melbourne, Parkville, Victoria, Australia
| | - Richard B Pearson
- Oncogenic Signalling and Growth Control Program, Peter MacCallum Cancer Centre, East Melbourne, Victoria, Australia; Department of Biochemistry and Molecular Biology, The University of Melbourne, Parkville, Victoria, Australia; Sir Peter MacCallum Department of Oncology, The University of Melbourne, Parkville, Victoria, Australia; Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia
| | - Ross D Hannan
- Oncogenic Signalling and Growth Control Program, Peter MacCallum Cancer Centre, East Melbourne, Victoria, Australia; Department of Biochemistry and Molecular Biology, The University of Melbourne, Parkville, Victoria, Australia; Sir Peter MacCallum Department of Oncology, The University of Melbourne, Parkville, Victoria, Australia; Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia; Department of Pathology, The University of Melbourne, Parkville, Victoria, Australia; School of Biomedical Sciences, The University of Queensland, St Lucia, Queensland, Australia.
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20
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Thanisch K, Schneider K, Morbitzer R, Solovei I, Lahaye T, Bultmann S, Leonhardt H. Targeting and tracing of specific DNA sequences with dTALEs in living cells. Nucleic Acids Res 2013; 42:e38. [PMID: 24371265 PMCID: PMC3973286 DOI: 10.1093/nar/gkt1348] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Epigenetic regulation of gene expression involves, besides DNA and histone modifications, the relative positioning of DNA sequences within the nucleus. To trace specific DNA sequences in living cells, we used programmable sequence-specific DNA binding of designer transcription activator-like effectors (dTALEs). We designed a recombinant dTALE (msTALE) with variable repeat domains to specifically bind a 19-bp target sequence of major satellite DNA. The msTALE was fused with green fluorescent protein (GFP) and stably expressed in mouse embryonic stem cells. Hybridization with a major satellite probe (3D-fluorescent in situ hybridization) and co-staining for known cellular structures confirmed in vivo binding of the GFP-msTALE to major satellite DNA present at nuclear chromocenters. Dual tracing of major satellite DNA and the replication machinery throughout S-phase showed co-localization during mid to late S-phase, directly demonstrating the late replication timing of major satellite DNA. Fluorescence bleaching experiments indicated a relatively stable but still dynamic binding, with mean residence times in the range of minutes. Fluorescently labeled dTALEs open new perspectives to target and trace DNA sequences and to monitor dynamic changes in subnuclear positioning as well as interactions with functional nuclear structures during cell cycle progression and cellular differentiation.
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Affiliation(s)
- Katharina Thanisch
- Department of Biology II, Humanbiology and Bioimaging, Center for Integrated Protein Science Munich (CIPSM), Ludwig Maximilians University Munich, 82152 Planegg-Martinsried, Germany and Department of Biology I, Genetics, Ludwig Maximilians University Munich, 82152 Planegg-Martinsried, Germany
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Subnuclear relocalization and silencing of a chromosomal region by an ectopic ribosomal DNA repeat. Proc Natl Acad Sci U S A 2013; 110:E4465-73. [PMID: 24191010 DOI: 10.1073/pnas.1315581110] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Our research addresses the relationship between subnuclear localization and gene expression in fission yeast. We observed the relocalization of a heterochromatic region, the mating-type region, from its natural location at the spindle-pole body to the immediate vicinity of the nucleolus. Relocalization occurred in response to a DNA rearrangement replacing a boundary element (IR-R) with a ribosomal DNA repeat (rDNA-R). Gene expression was strongly silenced in the relocalized mating-type region through mechanisms that differ from those operating in wild type. Also different from the wild-type situation, programmed recombination events failed to take place in the rDNA-R mutant. Increased silencing and perinucleolar localization depended on Reb1, a DNA-binding protein with cognate sites in the rDNA. Reb1 was recently shown to mediate long-range interchromosomal interactions in the nucleus through dimerization, providing a mechanism for the observed relocalization. Replacing the full rDNA repeat with Reb1-binding sites, and using mutants lacking the histone H3K9 methyltransferase Clr4, indicated that the relocalized region was silenced redundantly by heterochromatin and another mechanism, plausibly antisense transcription, achieving a high degree of repression in the rDNA-R strain.
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22
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Fujii Y, Yurkon CR, Maeda J, Genet SC, Okayasu R, Kitamura H, Fujimori A, Kato TA. Influence of track directions on the biological consequences in cells irradiated with high LET heavy ions. Int J Radiat Biol 2013; 89:401-10. [PMID: 23363030 DOI: 10.3109/09553002.2013.767990] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
PURPOSE The impact of the damage distribution to cellular survival and chromosomal aberrations following high Linear Energy Transfer (LET) radiation was investigated. MATERIALS AND METHODS High LET iron-ions (500 MeV/n, LET 200 keV/μm) were delivered to G1-phase synchronized Chinese Hamster Ovary (CHO) cells located at a vertical or horizontal angle relative to the ion beam in order to give same dose but different fluence and damage distribution. RESULTS Horizontal irradiation produced DNA double-strand break (DSB) along each ion track represented as clustered lines, and vertical irradiation produced a greater fluence. The initial damages measured by premature chromosome condensation were equal per dose in both irradiation types. Horizontal irradiation proved to be less effective in cell killing than vertical at doses of more than 3 Gy. Vertical irradiation produced a higher number of metaphase chromosomal aberrations compared to horizontally irradiated samples. In particular, formation of exchange-type aberrations was the same, but that of deletion-type aberrations were significantly higher after vertical irradiation than horizontal irradiation. CONCLUSIONS Therefore, we concluded that high fluence per dose is more effective than low fluence per dose to produce radiation-induced chromosomal aberrations and to kill exposed cells following high LET heavy-ion exposure.
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Affiliation(s)
- Yoshihiro Fujii
- Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, Inage, Chiba, Japan
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23
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Steglich B, Filion GJ, van Steensel B, Ekwall K. The inner nuclear membrane proteins Man1 and Ima1 link to two different types of chromatin at the nuclear periphery in S. pombe. Nucleus 2012; 3:77-87. [PMID: 22156748 DOI: 10.4161/nucl.18825] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Metazoan chromatin at the nuclear periphery is generally characterized by lowly expressed genes and repressive chromatin marks and presents a sub-compartment with properties distinct from the nuclear interior. To test whether the S. pombe nuclear periphery behaves similarly, we used DNA adenine methyltransferase identification (DamID) to map the target loci of two inner nuclear membrane proteins, Ima1 and Man1. We found that peripheral chromatin shows low levels of RNA-Polymerase II and nucleosome occupancy, both characteristic of repressed chromatin regions. Consistently, lowly expressed genes preferentially associate with the periphery and highly expressed genes are depleted from it. When looking at peripheral intergenic regions (IGRs), we found that divergent IGRs are enriched compared with convergent IGRs, indicating that transcription preferentially points away from the periphery rather than toward it. Interestingly, we found that Ima1 and Man1 have common, but also separate target regions in the genome. Ima1-interacting loci were enriched for the RNAi components Dcr1 and Rdp1. This agrees with previous findings that Dcr1 is localized at the nuclear periphery. In contrast, Man1 target loci were bound by the heterochromatin protein Swi6, especially at subtelomeric regions. Subtelomeric chromatin was shown to form a unique chromatin type lacking both repressive and active chromatin features and containing low levels of the histone variant H2A.Z. Thus, we find that the fission yeast nuclear periphery shows similar properties to those of metazoan cells, despite the absence of a nuclear lamina. Our results point to a role of nuclear membrane proteins in organizing chromatin domains and loops.
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Affiliation(s)
- Babett Steglich
- Center for Biosciences, Department of Biosciences and Nutrition, Karolinska Institute, Huddinge, Sweden
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24
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Chaudhuri JP, Walther JU. Nuclear segmentation, condensation and bilateral symmetry in polymorphonuclear leukocytes reflect genomic order and favor immunologic function. Acta Haematol 2012; 129:159-68. [PMID: 23234839 DOI: 10.1159/000343037] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2012] [Accepted: 08/29/2012] [Indexed: 11/19/2022]
Abstract
Segmentation, condensation and bilateral symmetry of the nuclei of polymorphonuclear leukocytes seem related to their function. Segmentation of the nuclei into two or more lobes and their condensation facilitate their passage (diapedesis) through the endothelial layer of blood vessels to the extravasal space and subsequent locomotion through the interstitial compartment of different tissues. Bilateral symmetry of these nuclei along with their association to the cytoskeletal fibers contribute to their efficiency in locomotion by alignment of the axis of nuclear symmetry to the axis of cellular polarity, which orients towards the direction of locomotion in response to cytokines and other stimuli. Observations of the cytogenetic facets of intranuclear order support these assumptions.
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25
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Dialynas G, Flannery KM, Zirbel LN, Nagy PL, Mathews KD, Moore SA, Wallrath LL. LMNA variants cause cytoplasmic distribution of nuclear pore proteins in Drosophila and human muscle. Hum Mol Genet 2011; 21:1544-56. [PMID: 22186027 PMCID: PMC3298278 DOI: 10.1093/hmg/ddr592] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Mutations in the human LMNA gene, encoding A-type lamins, give rise to laminopathies, which include several types of muscular dystrophy. Here, heterozygous sequence variants in LMNA, which result in single amino-acid substitutions, were identified in patients exhibiting muscle weakness. To assess whether the substitutions altered lamin function, we performed in vivo analyses using a Drosophila model. Stocks were generated that expressed mutant forms of the Drosophila A-type lamin modeled after each variant. Larvae were used for motility assays and histochemical staining of the body-wall muscle. In parallel, immunohistochemical analyses were performed on human muscle biopsy samples from the patients. In control flies, muscle-specific expression of the wild-type A-type lamin had no apparent affect. In contrast, expression of the mutant A-type lamins caused dominant larval muscle defects and semi-lethality at the pupal stage. Histochemical staining of larval body wall muscle revealed that the mutant A-type lamin, B-type lamins, the Sad1p, UNC-84 domain protein Klaroid and nuclear pore complex proteins were mislocalized to the cytoplasm. In addition, cytoplasmic actin filaments were disorganized, suggesting links between the nuclear lamina and the cytoskeleton were disrupted. Muscle biopsies from the patients showed dystrophic histopathology and architectural abnormalities similar to the Drosophila larvae, including cytoplasmic distribution of nuclear envelope proteins. These data provide evidence that the Drosophila model can be used to assess the function of novel LMNA mutations and support the idea that loss of cellular compartmentalization of nuclear proteins contributes to muscle disease pathogenesis.
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Affiliation(s)
- George Dialynas
- Department of Biochemistry, University of Iowa, Iowa City, IA 52242, USA
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26
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van Koningsbruggen S, Gierlinski M, Schofield P, Martin D, Barton GJ, Ariyurek Y, den Dunnen JT, Lamond AI. High-resolution whole-genome sequencing reveals that specific chromatin domains from most human chromosomes associate with nucleoli. Mol Biol Cell 2010; 21:3735-48. [PMID: 20826608 PMCID: PMC2965689 DOI: 10.1091/mbc.e10-06-0508] [Citation(s) in RCA: 231] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The nuclear space is mostly occupied by chromosome territories and nuclear bodies. Although this organization of chromosomes affects gene function, relatively little is known about the role of nuclear bodies in the organization of chromosomal regions. The nucleolus is the best-studied subnuclear structure and forms around the rRNA repeat gene clusters on the acrocentric chromosomes. In addition to rDNA, other chromatin sequences also surround the nucleolar surface and may even loop into the nucleolus. These additional nucleolar-associated domains (NADs) have not been well characterized. We present here a whole-genome, high-resolution analysis of chromatin endogenously associated with nucleoli. We have used a combination of three complementary approaches, namely fluorescence comparative genome hybridization, high-throughput deep DNA sequencing and photoactivation combined with time-lapse fluorescence microscopy. The data show that specific sequences from most human chromosomes, in addition to the rDNA repeat units, associate with nucleoli in a reproducible and heritable manner. NADs have in common a high density of AT-rich sequence elements, low gene density and a statistically significant enrichment in transcriptionally repressed genes. Unexpectedly, both the direct DNA sequencing and fluorescence photoactivation data show that certain chromatin loci can specifically associate with either the nucleolus, or the nuclear envelope.
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Affiliation(s)
- Silvana van Koningsbruggen
- Wellcome Trust Centre for Gene Regulation and Expression, College of Life Sciences, University of Dundee, Dundee DD1 5EH, United Kingdom
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Rouquette J, Cremer C, Cremer T, Fakan S. Functional nuclear architecture studied by microscopy: present and future. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2010; 282:1-90. [PMID: 20630466 DOI: 10.1016/s1937-6448(10)82001-5] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
In this review we describe major contributions of light and electron microscopic approaches to the present understanding of functional nuclear architecture. The large gap of knowledge, which must still be bridged from the molecular level to the level of higher order structure, is emphasized by differences of currently discussed models of nuclear architecture. Molecular biological tools represent new means for the multicolor visualization of various nuclear components in living cells. New achievements offer the possibility to surpass the resolution limit of conventional light microscopy down to the nanometer scale and require improved bioinformatics tools able to handle the analysis of large amounts of data. In combination with the much higher resolution of electron microscopic methods, including ultrastructural cytochemistry, correlative microscopy of the same cells in their living and fixed state is the approach of choice to combine the advantages of different techniques. This will make possible future analyses of cell type- and species-specific differences of nuclear architecture in more detail and to put different models to critical tests.
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Affiliation(s)
- Jacques Rouquette
- Biocenter, Ludwig Maximilians University (LMU), Martinsried, Germany
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28
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Mekhail K, Moazed D. The nuclear envelope in genome organization, expression and stability. Nat Rev Mol Cell Biol 2010; 11:317-28. [PMID: 20414256 DOI: 10.1038/nrm2894] [Citation(s) in RCA: 223] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Non-random positioning of chromosomal domains relative to each other and to nuclear landmarks is a common feature of eukaryotic genomes. In particular, the distribution of DNA loci relative to the nuclear periphery has been linked to both transcriptional activation and repression. Nuclear pores and other integral membrane protein complexes are key players in the dynamic organization of the genome in the nucleus, and recent advances in our understanding of the molecular networks that organize genomes at the nuclear periphery point to a further role for non-random locus positioning in DNA repair, recombination and stability.
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Affiliation(s)
- Karim Mekhail
- Department of Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto, 1 Kings College Circle, Toronto, Ontario, Canada.
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30
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Banfalvi G. Chromatin Fiber Structure and Plectonemic Model of Chromosome Condensation inDrosophilaCells. DNA Cell Biol 2008; 27:65-70. [DOI: 10.1089/dna.2007.0671] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Gaspar Banfalvi
- Department of Microbial Biotechnology and Cell Biology, University of Debrecen, Debrecen, Hungary
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31
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Kosak ST, Scalzo D, Alworth SV, Li F, Palmer S, Enver T, Lee JSJ, Groudine M. Coordinate gene regulation during hematopoiesis is related to genomic organization. PLoS Biol 2007; 5:e309. [PMID: 18031200 PMCID: PMC2080650 DOI: 10.1371/journal.pbio.0050309] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2006] [Accepted: 09/25/2007] [Indexed: 01/31/2023] Open
Abstract
Gene loci are found in nuclear subcompartments that are related to their expression status. For instance, silent genes are often localized to heterochromatin and the nuclear periphery, whereas active genes tend to be found in the nuclear center. Evidence also suggests that chromosomes may be specifically positioned within the nucleus; however, the nature of this organization and how it is achieved are not yet fully understood. To examine whether gene regulation is related to a discernible pattern of genomic organization, we analyzed the linear arrangement of co-regulated genes along chromosomes and determined the organization of chromosomes during the differentiation of a hematopoietic progenitor to erythroid and neutrophil cell types. Our analysis reveals that there is a significant tendency for co-regulated genes to be proximal, which is related to the association of homologous chromosomes and the spatial juxtaposition of lineage-specific gene domains. We suggest that proximity in the form of chromosomal gene distribution and homolog association may be the basis for organizing the genome for coordinate gene regulation during cellular differentiation.
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Affiliation(s)
- Steven T Kosak
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
| | - David Scalzo
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
| | - Sam V Alworth
- SVision, Bellevue, Washington, United States of America
| | - Fusheng Li
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
| | - Stephanie Palmer
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
| | - Tariq Enver
- MRC Molecular Haematology Unit, Oxford University, United Kingdom
| | | | - Mark Groudine
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America
- Department of Radiation Oncology, University of Washington School of Medicine, Seattle, Washington, United States of America
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32
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Ahmed S, Brickner JH. Regulation and epigenetic control of transcription at the nuclear periphery. Trends Genet 2007; 23:396-402. [PMID: 17566592 DOI: 10.1016/j.tig.2007.05.009] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2007] [Revised: 05/17/2007] [Accepted: 05/17/2007] [Indexed: 01/25/2023]
Abstract
The localization of DNA within the nucleus influences the regulation of gene transcription. Subnuclear environments at the nuclear periphery promote gene silencing and activation. Silenced regions of the genome, such as centromeres and telomeres, are statically tethered to the nuclear envelope. Recent work in yeast has revealed that certain genes can undergo dynamic recruitment to the periphery upon transcriptional activation. For such genes, localization to the periphery has been suggested to improve mRNA export and favor optimal transcription. In addition, maintenance of peripheral localization confers cellular memory of previous transcriptional activation, enabling cells to adapt rapidly to transcriptional cues.
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Affiliation(s)
- Sara Ahmed
- Department of Biochemistry, Molecular Biology and Cell Biology Northwestern University, Evanston, IL 60208, USA
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33
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Smetana K, Otevřelová P, Kalousek I. Heterochromatin density in the course of cell "dedifferentiation" represented by blastic transformation of human mature T lymphocytes. J Appl Biomed 2007. [DOI: 10.32725/jab.2007.025] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
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GREGORY TRYAN. Coincidence, coevolution, or causation? DNA content, cellsize, and the C-value enigma. Biol Rev Camb Philos Soc 2007. [DOI: 10.1111/j.1469-185x.2000.tb00059.x] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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35
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Thakar R, Gordon G, Csink AK. Dynamics and anchoring of heterochromatic loci during development. J Cell Sci 2006; 119:4165-75. [PMID: 16984972 DOI: 10.1242/jcs.03183] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Positioning a euchromatic gene near heterochromatin can influence its expression. To better understand expression-relevant changes in locus positioning, we monitored in vivo movement of centromeres and a euchromatic locus (with and without a nearby insertion of heterochromatin) in developing Drosophila tissue. In most undifferentiated nuclei, the rate of diffusion and step size of the locus is unaffected by the heterochromatic insertion. Interestingly, although the movement observed here is non directional, the heterochromatic insertion allows the flanking euchromatic region to enter and move within the heterochromatic compartment. This study also finds that a constraint on chromatin movement is imposed which is a factor of distance from the centric heterochromatic compartment. This restraint prevents the heterochromatic locus from moving away from the centric heterochromatin compartment. Therefore, because of the constraint, even distinct and non-random nuclear organizations can be attained from random chromatin movements. We also find a general constraint on chromatin movement is imposed during differentiation, which stabilizes changes in nuclear organization in differentiated nuclei.
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Affiliation(s)
- Rajika Thakar
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA 15213, USA
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36
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Garagna S, Merico V, Sebastiano V, Monti M, Orlandini G, Gatti R, Scandroglio R, Redi CA, Zuccotti M. Three-dimensional localization and dynamics of centromeres in mouse oocytes during folliculogenesis. J Mol Histol 2005; 35:631-8. [PMID: 15614617 DOI: 10.1007/s10735-004-2190-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2003] [Revised: 01/19/2004] [Indexed: 12/13/2022]
Abstract
Very little is known about oocyte nuclear architecture during folliculogenesis. Using antibodies to reveal centromeres, Hoechst-staining to detect the AT-rich pericentromeric heterochromatin (chromocenters), combined with confocal microscopy for the three-dimensional analysis of the nucleus, we demonstrate that during mouse folliculogenesis the oocyte nuclear architecture undergoes dynamic changes. In oocytes isolated from primordial and primary follicles, centromeres and chromocenters were preferentially located at the periphery of the nucleus. During oocyte growth, centromeres and chromocenters were initially found spread within the nucleus and then progressively clustered around the periphery of the nucleolus. Our results indicate that the oocyte nuclear achitecture is developmentally regulated and they contribute to a further understanding of the role of nuclear organization in the regulation of genome functioning during differentiation and development.
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Affiliation(s)
- Silvia Garagna
- Laboratorio di Biologia dello Sviluppo e Centro di Eccellenza in Biologia Applicata, Universita' degli Studi di Pavia, 27100 Pavia, Italy
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37
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Gacsi M, Nagy G, Pinter G, Basnakian AG, Banfalvi G. Condensation of interphase chromatin in nuclei of synchronized chinese hamster ovary (CHO-K1) cells. DNA Cell Biol 2005; 24:43-53. [PMID: 15684719 DOI: 10.1089/dna.2005.24.43] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Reversibly permeabilized cells have been used to visualize interphase chromatin structures in the presence and absence of biotinylated nucleotides. By reversing permeabilization, it was possible to confirm the existence of a flexible chromatin folding pattern through a series of transient geometric forms such as supercoiled, circular forms, chromatin bodies, thin and thick fibers, and elongated chromosomes. Our results show that the incorporation of biotin-11-dUTP interferes with chromatin condensation, leading to the accumulation of decondensed chromatin structures. Chromatin condensation without nucleotide incorporation was also studied in cell populations synchronized by centrifugal elutriation. After reversal of permeabilization, nuclei were isolated and chromatin structures were visualized after DAPI staining by fluorescent microscopy. Decondensed veil-like structures were observed in the early S phase (at an average C-value of 2.21), supercoiled chromatin later in the early S (2, 55 C), fibrous structures in the early mid S phase (2, 76 C), ribboned structures in the mid-S phase (2, 98 C), continuous chromatin strings later in the mid-S phase (3,28), elongated prechromosomes in the late S-phase (3, 72 C), precondensed chromosomes at the end and after the S phase (3, 99 C). Fluorescent microscopy revealed that neither interphase nor metaphase chromosomes are separate entities but form a linear array arranged in a semicircle. Linear arrangement was confirmed by computer image analysis.
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Affiliation(s)
- Mariann Gacsi
- Department of Animal Anatomy and Physiology, University of Debrecen, Debrecen, Hungary
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38
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Tam R, Smith KP, Lawrence JB. The 4q subtelomere harboring the FSHD locus is specifically anchored with peripheral heterochromatin unlike most human telomeres. ACTA ACUST UNITED AC 2004; 167:269-79. [PMID: 15504910 PMCID: PMC2172553 DOI: 10.1083/jcb.200403128] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
This paper investigates the nuclear localization of human telomeres and, specifically, the 4q35 subtelomere mutated in facioscapulohumeral dystrophy (FSHD). FSHD is a common muscular dystrophy that has been linked to contraction of D4Z4 tandem repeats, widely postulated to affect distant gene expression. Most human telomeres, such as 17q and 17p, avoid the nuclear periphery to reside within the internal, euchromatic compartment. In contrast, 4q35 localizes at the peripheral heterochromatin with 4p more internal, generating a reproducible chromosome orientation that we relate to gene expression profiles. Studies of hybrid and translocation cell lines indicate this localization is inherent to the distal tip of 4q. Investigation of heterozygous FSHD myoblasts demonstrated no significant displacement of the mutant allele from the nuclear periphery. However, consistent association of the pathogenic D4Z4 locus with the heterochromatic compartment supports a potential role in regulating the heterochromatic state and makes a telomere positioning effect more likely. Furthermore, D4Z4 repeats on other chromosomes also frequently organize with the heterochromatic compartment at the nuclear or nucleolar periphery, demonstrating a commonality among chromosomes harboring this subtelomere repeat family.
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Affiliation(s)
- Rose Tam
- Department of Cell Biology, University of Massachusetts Medical School, Worcester, MA 01655, USA
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39
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Lowenstein MG, Goddard TD, Sedat JW. Long-range interphase chromosome organization in Drosophila: a study using color barcoded fluorescence in situ hybridization and structural clustering analysis. Mol Biol Cell 2004; 15:5678-92. [PMID: 15371546 PMCID: PMC532046 DOI: 10.1091/mbc.e04-04-0289] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
We have developed a color barcode labeling strategy for use with fluorescence in situ hybridization that enables the discrimination of multiple, identically labeled loci. Barcode labeling of chromosomes provides long-range path information and allows structural analysis at a scale and resolution beyond what was previously possible. Here, we demonstrate the use of a three-color, 13-probe barcode for the structural analysis of Drosophila chromosome 2L in blastoderm stage embryos. We observe the chromosome to be strongly polarized in the Rabl orientation and for some loci to assume defined positions relative to the nuclear envelope. Our analysis indicates packing approximately 15- to 28-fold above the 30-nm fiber, which varies along the chromosome in a pattern conserved across embryos. Using a clustering implementation based on rigid body alignment, our analysis suggests that structures within each embryo represent a single population and are effectively modeled as oriented random coils confined within nuclear boundaries. We also found an increased similarity between homologous chromosomes that have begun to pair. Chromosomes in embryos at equivalent developmental stages were found to share structural features and nuclear localization, although size-related differences that correlate with the cell cycle also were observed. The methodology and tools we describe provide a direct means for identifying developmental and cell type-specific features of higher order chromosome and nuclear organization.
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Affiliation(s)
- Michael G Lowenstein
- Graduate Group in Biophysics, University of California, San Francisco, San Francisco, CA 94143, USA
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40
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Guenatri M, Bailly D, Maison C, Almouzni G. Mouse centric and pericentric satellite repeats form distinct functional heterochromatin. ACTA ACUST UNITED AC 2004; 166:493-505. [PMID: 15302854 PMCID: PMC2172221 DOI: 10.1083/jcb.200403109] [Citation(s) in RCA: 378] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Heterochromatin is thought to play a critical role for centromeric function. However, the respective contributions of the distinct repetitive sequences found in these regions, such as minor and major satellites in the mouse, have remained largely unsolved. We show that these centric and pericentric repeats on the chromosomes have distinct heterochromatic characteristics in the nucleus. Major satellites from different chromosomes form clusters associated with heterochromatin protein 1α, whereas minor satellites are individual entities associated with centromeric proteins. Both regions contain methylated histone H3 (Me-K9 H3) but show different micrococcal nuclease sensitivities. A dinucleosome repeating unit is found specifically associated with major satellites. These domains replicate asynchronously, and chromatid cohesion is sustained for a longer time in major satellites compared with minor satellites. Such prolonged cohesion in major satellites is lost in the absence of Suv39h histone methyltransferases. Thus, we define functionally independent centromeric subdomains, which spatio-temporal isolation is proposed to be important for centromeric cohesion and dissociation during chromosome segregation.
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Affiliation(s)
- Mounia Guenatri
- Institut Curie/Research section, UMR218 du Centre National pour la Recherche Scientifique, 26 rue d'Ulm, 75248 Paris Cedex 05, France
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41
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Lorenz A, Fuchs J, Bürger R, Loidl J. Chromosome pairing does not contribute to nuclear architecture in vegetative yeast cells. EUKARYOTIC CELL 2004; 2:856-66. [PMID: 14555468 PMCID: PMC219365 DOI: 10.1128/ec.2.5.856-866.2003] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
There are several reports of a closer-than-random colocalization of homologous chromosomes in the vegetative nuclei of diploid budding yeast. Here, we studied by fluorescence in situ hybridization (FISH) the nuclear distribution of chromosomes and found a slight tendency toward closer proximity between homologous (allelic) loci than between any nonhomologous chromosomal regions. We show that most of this preferential association is not due to vegetative (also known as somatic) pairing but is caused by the polar orientation of interphase chromosomes (Rabl orientation). We quantified the occasional loss of detectable fluorescence signals that is inherent to the FISH method. Signal loss leads to the occurrence of a single signal that may be misinterpreted as the close association of two homologous chromosomal sites. The nuclear distribution of homologous loci, when corrected for the influence of nuclear architecture and methodological faults, was not different or was only marginally different from a random relative positioning as predicted by computer simulation. We discuss here several possibilities for the residual homologous proximity that do not invoke homology-dependent vegetative pairing, and we conclude that, in diploid budding yeast, constitutive vegetative pairing is a negligible factor for the organization of the interphase nucleus.
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42
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Abstract
A number of recent studies have indicated that the location of a given mammalian chromosome within the interphase nucleus is related to its size, whereas other work has implicated a chromosome's gene density as a factor. Recent investigations of the degree to which an ordered arrangement of mitotic chromosomes on the metaphase plate is inherited and perpetuated during successive cell cycles have also yielded somewhat controversial results. The arrangement of chromosomes in the nucleus also has been investigated by the analysis of chromosomal translocations, with some surprising recent findings.
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Affiliation(s)
- Thoru Pederson
- Program in Cell Dynamics and Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01605, USA.
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43
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Podgornaya OI, Voronin AP, Enukashvily NI, Matveev IV, Lobov IB. Structure-specific DNA-binding proteins as the foundation for three-dimensional chromatin organization. INTERNATIONAL REVIEW OF CYTOLOGY 2003; 224:227-96. [PMID: 12722952 DOI: 10.1016/s0074-7696(05)24006-8] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Any functions of tandem repetitive sequences need proteins that specifically bind to them. Telomere-binding TRF2/MTBP attaches telomeres to the nuclear envelope in interphase due to its rod-domain-like motif. Interphase nuclei organized as a number of sponge-like ruffly round chromosome territories that could be rotated from outside. SAF-A/hnRNP-U and p68-helicase are proteins suitable to do that. Their location in the interchromosome territory space, ATPase domains, and the ability to be bound by satellite DNAs (satDNA) make them part of the wires used to help chromosome territory rotates. In case of active transcription p68-helicase can be involved in the formation of local "gene expression matrices" and due to its satDNA-binding specificity cause the rearrangement of the local chromosome territory. The marks of chromatin rearrangement, which have to be heritable, could be provided by SAF-A/hnRNP-U. During telophase unfolding the proper chromatin arrangement is restored according to these marks. The structural specificity of both proteins to the satDNAs provides a regulative but relatively stable mode of binding. The structural specificity of protein binding could help to find the "magic" centromeric sequence. With future investigations of proteins with the structural specificity of binding during early embryogenesis, when heterochromatin formation goes on, the molecular mechanisms of the "gene gating" hypothesis (Blobel, 1985) will be confirmed.
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Affiliation(s)
- O I Podgornaya
- Institute of Cytology, Russian Academy of Sciences, St. Petersburg 194064, Russia
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44
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Amrichová J, Lukásová E, Kozubek S, Kozubek M. Nuclear and territorial topography of chromosome telomeres in human lymphocytes. Exp Cell Res 2003; 289:11-26. [PMID: 12941600 DOI: 10.1016/s0014-4827(03)00208-8] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Nuclear and territorial positioning of p- and q-telomeres and centromeres of chromosomes 3, 8, 9, 13, and 19 were studied by repeated fluorescence in situ hybridization, high-resolution cytometry, and three-dimensional image analysis in human blood lymphocytes before and after stimulation. Telomeres were found on the opposite side of the territories as compared with the centromeres for all chromosome territories investigated. Mutual distances between telomeres of submetacentric chromosomes were very short, usually shorter than centromere-to-telomere distances, which means that the chromosome territory is nonrandomly folded. Telomeres are, on average, much nearer to the center of the cell nucleus than centromeres; q-telomeres were found, on average, more centrally localized as compared with p-telomeres. Consequently, we directly showed that chromosome territories in the cell nucleus are (1) polar and (2) partially oriented in cell nuclei. The distributions of genetic elements relative to chromosome territories (territorial distributions) can be either narrower or broader than their nuclear distributions, which reflects the degree of adhesion of an element to the territory or to the nucleus. We found no tethering of heterologous telomeres of chromosomes 8, 9, and 19. In contrast, both pairs of homologous telomeres of chromosome 19 (but not in other chromosomes) are tethered (associated) very frequently.
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MESH Headings
- Cell Compartmentation/genetics
- Cell Nucleus/genetics
- Cell Nucleus/ultrastructure
- Cell Polarity/genetics
- Centromere/genetics
- Chromosomes/genetics
- Chromosomes/ultrastructure
- Chromosomes, Human, Pair 13/genetics
- Chromosomes, Human, Pair 13/ultrastructure
- Chromosomes, Human, Pair 19/genetics
- Chromosomes, Human, Pair 19/ultrastructure
- Chromosomes, Human, Pair 3/genetics
- Chromosomes, Human, Pair 3/ultrastructure
- Chromosomes, Human, Pair 8/genetics
- Chromosomes, Human, Pair 8/ultrastructure
- Chromosomes, Human, Pair 9/genetics
- Chromosomes, Human, Pair 9/ultrastructure
- Humans
- Interphase/genetics
- Lymphocytes/cytology
- Lymphocytes/physiology
- Telomere/genetics
- Telomere/ultrastructure
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Affiliation(s)
- Jana Amrichová
- Laboratory of Optical Microscopy, Faculty of Informatics, Masaryk University, Botanická 68a, 602 00, Brno, Czech Republic
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45
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Dolnik AV, Kuznetsova IS, Voronin AP, Podgornaya OI. Telomere-Binding TRF2/MTBP Localization during Mouse Spermatogenesis and Cell Cycle of the Mouse Cells L929. ACTA ACUST UNITED AC 2003; 6:107-21. [PMID: 14614800 DOI: 10.1089/109454503769684784] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Observations of the organization and distribution of telomeres (Tel) in somatic tissues still remain controversial. The Tel topography revealed by modern microscopy shows them to be associated with the nuclear envelope (NE) in a wide variety of eukaryotic cells, although not at the Rabl orientation (peripheral position at one pole of the nucleus at prophase). We used two cell types that have different nuclear architectures. The cell line L929 shows lack of any rigid Tel architecture in the nucleus. In contrast, spermatozoa have a precise architecture established during spermiogenesis. We observed Tel and membrane Tel binding protein (MTBP/TRF2) position by immunoFISH in L929 cells and by immunofluorescence and immunogold electron microscopy, using antibodies against Membrane Tel Binding Protein (MTBP/TRF2), during different stages of spermiogenesis. At all stages of the L929 cell cycle, MTBP/TRF2 is co-localized with Tel. The only Tel order found in this cell type is similar to the Rabl-orientation, probably due to fast divisions. In the mouse pachytene spermatocytes, the membrane structures abut on the synaptonemal complex (SC) attachment sites contain MTBP/TRF2. In fully formed spermatozoa and during spermiogenesis, apart from the expected MTBP/TRF2 position at the nuclear periphery, MTBP/TRF2 unexpectedly localized at the acrosomal membrane that is adjacent to the nucleus. The difference in the MTBP/TRF2 distribution in the oocyte and spermatozoa leads to the suggestion that the MTBP/TRF2 location might reflect preparation for fertilization events. The Tel distribution is not static in cultured cells throughout the cell cycle or during spermatogenesis. When the Tel are attached to the NE, as during SC formation, MTBP/TRF2 is the member of the protein complex, which appears to be responsible for this attachment.
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Affiliation(s)
- A V Dolnik
- Institute of Cytology, Russian Academy of Sciences, St. Petersburg, Russia.
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46
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Loidl J. Chromosomes of the budding yeast Saccharomyces cerevisiae. INTERNATIONAL REVIEW OF CYTOLOGY 2003; 222:141-96. [PMID: 12503849 DOI: 10.1016/s0074-7696(02)22014-8] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The mitotic chromosomes of the baker's yeast, Saccharomyces cerevisiae, cannot be visualized by standard cytological methods. Only the study of meiotic bivalents and the synaptonemal complex and the visualization of chromosome-sized DNA molecules on pulsed-field gels have provided some insight into chromosome structure and behavior. More recently, advanced techniques such as in situ hybridization, the illumination of chromosomal loci by GFP-tagged DNA-binding proteins, and immunostaining of chromosomal proteins have promoted our knowledge about yeast chromosomes. These novel cytological approaches in combination with the yeast's advanced biochemistry and genetics have produced a great wealth of information on the interplay between molecular and cytological processes and have strengthened the role of yeast as a leading cell biological model organism. Recent cytological studies have revealed much about the chromosomal organization in interphase nuclei and have contributed significantly to our current understanding of chromosome condensation, sister chromatid cohesion, and centromere orientation in mitosis. Moreover, important details about the biochemistry and ultrastructure of meiotic pairing and recombination have been revealed by combined cytological and molecular approaches. This article covers several aspects of yeast chromosome structure, including their organization within interphase nuclei and their behavior during mitosis and meiosis.
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Affiliation(s)
- Josef Loidl
- Institute of Botany, University of Vienna, A-1030 Vienna, Austria
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47
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Sýkorová E, Cartagena J, Horáková M, Fukui K, Fajkus J. Characterization of telomere-subtelomere junctions in Silene latifolia. Mol Genet Genomics 2003; 269:13-20. [PMID: 12715149 DOI: 10.1007/s00438-003-0811-9] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2002] [Accepted: 12/30/2002] [Indexed: 11/30/2022]
Abstract
Telomere-associated regions represent boundaries between the relatively homogeneous telomeres and the subtelomeres, which show much greater heterogeneity in chromatin structure and DNA composition. Although a major fraction of subtelomeres is usually formed by a limited number of highly repeated DNA sequence families, their mutual arrangement, attachment to telomeres and the presence of interspersed unique or low-copy-number sequences make these terminal domains chromosome specific. In this study, we describe the structures of junctions between telomeres and a major subtelomeric repeat of the plant Silene latifolia, X43.1. Our results show that on individual chromosome arms, X43.1 is attached to the telomere either directly at sites corresponding to nucleosome boundaries previously mapped in this sequence, or via other spacer sequences, both previously characterized and newly described ones. Sites of telomere junctions are non-random in all the telomere-associated sequences analysed. These data obtained at the molecular level have been verified using in situ hybridization to metaphase chromosomes and extended DNA fibres.
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Affiliation(s)
- E Sýkorová
- Institute of Biophysics, Academy of Sciences of the Czech Republic, Královopolská 135, 61265 Brno, Czech Republic
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48
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Abstract
The notion that the interior of the nucleus is compartmentalized goes back to the discovery of the nucleolus in the 1830s. Today, we know that numerous, discrete domains related to gene expression exist within the interchromatin spaces of the interphase nucleus. These domains might arise from, and thus be positioned by, the transcriptional activity of the chromosomes, themselves tethered to the nuclear envelope, or they might assemble autonomously. Beyond their roles in gene expression or other nuclear functions, the dynamic behaviour of some of these interchromatin domains is providing clues to the modes of mass transport operating in the nucleus, as well as to the long-elusive deep structure of the nucleoplasm.
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Affiliation(s)
- Thoru Pederson
- Department of Biochemistry and Molecular Pharmacology, and Program in Cell Dynamics University of Massachusetts Medical School, Worcester, MA 01605, USA.
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49
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Bunting RW, Selig MK. Localization of DNA in ultrascopic nuclear appendages of polymorphonuclear white blood cells from patients with low serum B(12). J Histochem Cytochem 2002; 50:1381-8. [PMID: 12364571 DOI: 10.1177/002215540205001011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Polymorphonuclear white blood cells from patients with low serum vitamin B(12) (cobalamin) have ultrascopic appendages that project from their nuclear membranes. These appendages are most often found in the shape of blebs and stalks. Cytoplasmic rings that may be separated from the nucleus have also been seen. There is no known function for these appendages. Blood from 11 patients with low serum B(12) was processed for electron microscopic examination. In situ end-labeling of DNA and subsequent electron microscopic examination were performed. DNA was localized in all of the visualized appendages and rings. Treatment with DNases I and II decreased the labeling of these appendages by 63%. These DNA-laden appendages are a unique ultrastructural finding and may function to transfer fragmented DNA, which occurs in vitamin B(12) deficiency, from the nucleus into the cytoplasm.
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Affiliation(s)
- Robert W Bunting
- Department of Pathology, Harvard Medical School, and the James Homer Wright Laboratories of the Massachusetts General Hospital, Boston, Massachusetts 02114, USA.
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50
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Parada LA, McQueen PG, Munson PJ, Misteli T. Conservation of relative chromosome positioning in normal and cancer cells. Curr Biol 2002; 12:1692-7. [PMID: 12361574 DOI: 10.1016/s0960-9822(02)01166-1] [Citation(s) in RCA: 135] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Chromosomes exist in the interphase nucleus as individual chromosome territories. It is unclear to what extent chromosome territories occupy particular positions with respect to each other and how structural rearrangements, such as translocations, affect chromosome organization within the cell nucleus. Here we analyze the relative interphase positioning of chromosomes in mouse lymphoma cells compared to normal splenocytes. We show that in a lymphoma cell line derived from an ATM(-/-) mouse, two translocated chromosomes are preferentially positioned in close proximity to each other. The relative position of the chromosomes involved in these translocations is conserved in normal splenocytes. Relative positioning of chromosomes in normal splenocytes is not due to their random distribution in the interphase nucleus and persists during mitosis. These observations demonstrate that the relative arrangement of chromosomes in the interphase nucleus can be conserved between normal and cancer cells and our data support the notion that physical proximity facilitates rearrangements between chromosomes.
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Affiliation(s)
- Luis A Parada
- National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
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