301
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Gesson K, Vidak S, Foisner R. Lamina-associated polypeptide (LAP)2α and nucleoplasmic lamins in adult stem cell regulation and disease. Semin Cell Dev Biol 2013; 29:116-24. [PMID: 24374133 PMCID: PMC4053830 DOI: 10.1016/j.semcdb.2013.12.009] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2013] [Revised: 12/10/2013] [Accepted: 12/15/2013] [Indexed: 10/25/2022]
Abstract
A-type lamins are components of the lamina network at the nuclear envelope, which mediates nuclear stiffness and anchors chromatin to the nuclear periphery. However, A-type lamins are also found in the nuclear interior. Here we review the roles of the chromatin-associated, nucleoplasmic LEM protein, lamina-associated polypeptide 2α (LAP2α) in the regulation of A-type lamins in the nuclear interior. The lamin A/C-LAP2α complex may be involved in the regulation of the retinoblastoma protein-mediated pathway and other signaling pathways balancing proliferation and differentiation, and in the stabilization of higher-order chromatin organization throughout the nucleus. Loss of LAP2α in mice leads to selective depletion of the nucleoplasmic A-type lamin pool, promotes the proliferative stem cell phenotype of tissue progenitor cells, and delays stem cell differentiation. These findings support the hypothesis that LAP2α and nucleoplasmic lamins are regulators of adult stem cell function and tissue homeostasis. Finally, we discuss potential implications of this concept for defining the molecular disease mechanisms of lamin-linked diseases such as muscular dystrophy and premature aging syndromes.
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Affiliation(s)
- Kevin Gesson
- Max F. Perutz Laboratories, Department of Medical Biochemistry, Medical University Vienna, Dr. Bohr-Gasse 9, 1030 Vienna, Austria
| | - Sandra Vidak
- Max F. Perutz Laboratories, Department of Medical Biochemistry, Medical University Vienna, Dr. Bohr-Gasse 9, 1030 Vienna, Austria
| | - Roland Foisner
- Max F. Perutz Laboratories, Department of Medical Biochemistry, Medical University Vienna, Dr. Bohr-Gasse 9, 1030 Vienna, Austria.
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302
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Koch AJ, Holaska JM. Emerin in health and disease. Semin Cell Dev Biol 2013; 29:95-106. [PMID: 24365856 DOI: 10.1016/j.semcdb.2013.12.008] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Revised: 12/02/2013] [Accepted: 12/15/2013] [Indexed: 12/27/2022]
Abstract
Emery-Dreifuss muscular dystrophy (EDMD) is caused by mutations in the genes encoding emerin, lamins A and C and FHL1. Additional EDMD-like syndromes are caused by mutations in nesprins and LUMA. This review will specifically focus on emerin function and the current thinking for how loss or mutations in emerin cause EDMD. Emerin is a well-conserved, ubiquitously expressed protein of the inner nuclear membrane. Emerin has been shown to have diverse functions, including the regulation of gene expression, cell signaling, nuclear structure and chromatin architecture. This review will focus on the relationships between these functions and the EDMD disease phenotype. Additionally it will highlight open questions concerning emerin's roles in cell and nuclear biology and disease.
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Affiliation(s)
- Adam J Koch
- Committee on Genetics, Genomics and Systems Biology, The University of Chicago, Chicago, IL 60637, USA.
| | - James M Holaska
- Committee on Genetics, Genomics and Systems Biology, The University of Chicago, Chicago, IL 60637, USA; Committee on Developmental, Regeneration and Stem Cell Biology, The University of Chicago, Chicago, IL 60637, USA.
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303
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Seitan VC, Faure AJ, Zhan Y, McCord RP, Lajoie BR, Ing-Simmons E, Lenhard B, Giorgetti L, Heard E, Fisher AG, Flicek P, Dekker J, Merkenschlager M. Cohesin-based chromatin interactions enable regulated gene expression within preexisting architectural compartments. Genome Res 2013; 23:2066-77. [PMID: 24002784 PMCID: PMC3847776 DOI: 10.1101/gr.161620.113] [Citation(s) in RCA: 256] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2013] [Accepted: 08/28/2013] [Indexed: 01/09/2023]
Abstract
Chromosome conformation capture approaches have shown that interphase chromatin is partitioned into spatially segregated Mb-sized compartments and sub-Mb-sized topological domains. This compartmentalization is thought to facilitate the matching of genes and regulatory elements, but its precise function and mechanistic basis remain unknown. Cohesin controls chromosome topology to enable DNA repair and chromosome segregation in cycling cells. In addition, cohesin associates with active enhancers and promoters and with CTCF to form long-range interactions important for gene regulation. Although these findings suggest an important role for cohesin in genome organization, this role has not been assessed on a global scale. Unexpectedly, we find that architectural compartments are maintained in noncycling mouse thymocytes after genetic depletion of cohesin in vivo. Cohesin was, however, required for specific long-range interactions within compartments where cohesin-regulated genes reside. Cohesin depletion diminished interactions between cohesin-bound sites, whereas alternative interactions between chromatin features associated with transcriptional activation and repression became more prominent, with corresponding changes in gene expression. Our findings indicate that cohesin-mediated long-range interactions facilitate discrete gene expression states within preexisting chromosomal compartments.
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Affiliation(s)
- Vlad C. Seitan
- Lymphocyte Development Group, MRC Clinical Sciences Centre, Imperial College London, London W12 0NN, United Kingdom
| | - Andre J. Faure
- European Molecular Biology Laboratory, European Bioinformatics Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge CB10 1SD, United Kingdom
| | - Ye Zhan
- Program in Systems Biology, Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
| | - Rachel Patton McCord
- Program in Systems Biology, Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
| | - Bryan R. Lajoie
- Program in Systems Biology, Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
| | - Elizabeth Ing-Simmons
- Lymphocyte Development Group, MRC Clinical Sciences Centre, Imperial College London, London W12 0NN, United Kingdom
- Computational Regulatory Genomics Group, MRC Clinical Sciences Centre, Imperial College London, London W12 0NN, United Kingdom
| | - Boris Lenhard
- Computational Regulatory Genomics Group, MRC Clinical Sciences Centre, Imperial College London, London W12 0NN, United Kingdom
| | | | | | - Amanda G. Fisher
- Lymphocyte Development Group, MRC Clinical Sciences Centre, Imperial College London, London W12 0NN, United Kingdom
| | - Paul Flicek
- European Molecular Biology Laboratory, European Bioinformatics Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge CB10 1SD, United Kingdom
- Wellcome Trust Sanger Institute, Hinxton, Cambridge CB10 1SA, United Kingdom
| | - Job Dekker
- Program in Systems Biology, Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
| | - Matthias Merkenschlager
- Lymphocyte Development Group, MRC Clinical Sciences Centre, Imperial College London, London W12 0NN, United Kingdom
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304
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Collas P, Lund EG, Oldenburg AR. Closing the (nuclear) envelope on the genome: how nuclear lamins interact with promoters and modulate gene expression. Bioessays 2013; 36:75-83. [PMID: 24272858 DOI: 10.1002/bies.201300138] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The nuclear envelope shapes the functional organization of the nucleus. Increasing evidence indicates that one of its main components, the nuclear lamina, dynamically interacts with the genome, including the promoter region of specific genes. This seems to occur in a manner that accords developmental significance to these interactions. This essay addresses key issues raised by recent data on the association of nuclear lamins with the genome. We discuss how lamins interact with large chromatin domains and with spatially restricted regions on gene promoters. We address the relationship between these interactions, chromatin modifications and gene expression outcomes. Lamin-genome contacts are redistributed after cell division and during stem cell differentiation, with evidence of lineage specificity. Thus, we also speculate on a developmental role of lamin interactions with specific genes. Finally, we highlight how concepts arising from this recent work lay the foundations of future challenges and investigations.
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Affiliation(s)
- Philippe Collas
- Stem Cell Epigenetics Laboratory, Faculty of Medicine, Institute of Basic Medical Sciences, Norwegian Center for Stem Cell Research, University of Oslo, Oslo, Norway
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305
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Alsarraj J, Faraji F, Geiger TR, Mattaini KR, Williams M, Wu J, Ha NH, Merlino T, Walker RC, Bosley AD, Xiao Z, Andresson T, Esposito D, Smithers N, Lugo D, Prinjha R, Day A, Crawford NPS, Ozato K, Gardner K, Hunter KW. BRD4 short isoform interacts with RRP1B, SIPA1 and components of the LINC complex at the inner face of the nuclear membrane. PLoS One 2013; 8:e80746. [PMID: 24260471 PMCID: PMC3834312 DOI: 10.1371/journal.pone.0080746] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2013] [Accepted: 10/07/2013] [Indexed: 11/25/2022] Open
Abstract
Recent studies suggest that BET inhibitors are effective anti-cancer therapeutics. Here we show that BET inhibitors are effective against murine primary mammary tumors, but not pulmonary metastases. BRD4, a target of BET inhibitors, encodes two isoforms with opposite effects on tumor progression. To gain insights into why BET inhibition was ineffective against metastases the pro-metastatic short isoform of BRD4 was characterized using mass spectrometry and cellular fractionation. Our data show that the pro-metastatic short isoform interacts with the LINC complex and the metastasis-associated proteins RRP1B and SIPA1 at the inner face of the nuclear membrane. Furthermore, histone binding arrays revealed that the short isoform has a broader acetylated histone binding pattern relative to the long isoform. These differential biochemical and nuclear localization properties revealed in our study provide novel insights into the opposing roles of BRD4 isoforms in metastatic breast cancer progression.
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Affiliation(s)
- Jude Alsarraj
- Laboratory of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Farhoud Faraji
- Laboratory of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, United States of America
- Department of Biochemistry and Molecular Biology, School of Medicine, Saint Louis University, Saint Louis, Missouri, United States of America
| | - Thomas R. Geiger
- Laboratory of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Katherine R. Mattaini
- Laboratory of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Mia Williams
- Laboratory of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Josephine Wu
- Laboratory of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Ngoc-Han Ha
- Laboratory of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Tyler Merlino
- Laboratory of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Renard C. Walker
- Laboratory of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Allen D. Bosley
- Laboratory of Proteomics and Analytical Technologies, Frederick National Laboratory for Cancer Research, Frederick, Maryland, United States of America
| | - Zhen Xiao
- Laboratory of Proteomics and Analytical Technologies, Frederick National Laboratory for Cancer Research, Frederick, Maryland, United States of America
| | - Thorkell Andresson
- Laboratory of Proteomics and Analytical Technologies, Frederick National Laboratory for Cancer Research, Frederick, Maryland, United States of America
| | - Dominic Esposito
- Laboratory of Proteomics and Analytical Technologies, Frederick National Laboratory for Cancer Research, Frederick, Maryland, United States of America
| | - Nicholas Smithers
- Epinova DPU and Quantitative Pharmacology, Immuno-Inflammation Therapeutic Area, GlaxoSmithKline, Stevenage, United Kingdom
| | - Dave Lugo
- Epinova DPU and Quantitative Pharmacology, Immuno-Inflammation Therapeutic Area, GlaxoSmithKline, Stevenage, United Kingdom
| | - Rab Prinjha
- Epinova DPU and Quantitative Pharmacology, Immuno-Inflammation Therapeutic Area, GlaxoSmithKline, Stevenage, United Kingdom
| | - Anup Day
- Laboratory of Molecular Growth Regulation, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Nigel P. S. Crawford
- Cancer Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Keiko Ozato
- Laboratory of Molecular Growth Regulation, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Kevin Gardner
- Genetic Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Kent W. Hunter
- Laboratory of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, United States of America
- * E-mail:
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306
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Peripheral subnuclear positioning suppresses Tcrb recombination and segregates Tcrb alleles from RAG2. Proc Natl Acad Sci U S A 2013; 110:E4628-37. [PMID: 24218622 DOI: 10.1073/pnas.1310846110] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Allelic exclusion requires that the two alleles at antigen-receptor loci attempt to recombine variable (V), diversity (D), and joining (J) gene segments [V(D)J recombination] asynchronously in nuclei of developing lymphocytes. It previously was shown that T-cell receptor β (Tcrb) alleles frequently and stochastically associate with the nuclear lamina and pericentromeric heterochromatin in CD4(-)CD8(-) thymocytes. Moreover, rearranged alleles were underrepresented at these locations. Here we used 3D immunofluorescence in situ hybridization to identify recently rearranged Tcrb alleles based on the accumulation of the DNA-repair protein 53BP1. We found that Tcrb alleles recombine asynchronously in double-negative thymocytes and that V(D)J recombination is suppressed on peripheral as compared with central Tcrb alleles. Moreover, the recombination events that did take place at the nuclear periphery preferentially occurred on Tcrb alleles that were partially dissociated from the nuclear lamina. To understand better the mechanism by which V(D)J recombination is suppressed at the nuclear periphery, we evaluated the subnuclear distribution of recombination-activating gene 2 (RAG2) protein. We found that RAG2 abundance was reduced at the nuclear periphery. Moreover, RAG2 was distributed differently from RNA polymerase II and histone H3K4 trimethylation. Our data suggest that the nuclear periphery suppresses V(D)J recombination, at least in part, by segregating Tcrb alleles from RAG proteins.
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307
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Abstract
The nuclear lamina guards the genome and in many ways contributes to regulating nuclear function. Increasing evidence indicates that the lamina dynamically interacts with chromatin mainly through large repressive domains, and recent data suggest that at least some of the lamin-genome contacts may be developmentally significant. In an attempt to provide an additional meaning to lamin-genome contacts, a recent study characterized the association of gene promoters with A-type lamins in progenitor and differentiated cells. Here, we discuss how A-type lamins interact with spatially defined promoter regions, and the relationship between these interactions, associated chromatin marks and gene expression outputs. We discuss the impact of A-type lamins on nucleus-wide and local chromatin organization. We also address how lamin-promoter interactions are redistributed during differentiation of adipocyte progenitors into adipocytes. Finally, we propose a model of lineage-specific "unlocking" of developmentally regulated loci and its significance in cellular differentiation.
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Affiliation(s)
- Eivind Lund
- Stem Cell Epigenetics Laboratory; Institute of Basic Medical Sciences; Faculty of Medicine; University of Oslo, and Norwegian Center for Stem Cell Research; Oslo, Norway
| | - Philippe Collas
- Stem Cell Epigenetics Laboratory; Institute of Basic Medical Sciences; Faculty of Medicine; University of Oslo, and Norwegian Center for Stem Cell Research; Oslo, Norway
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308
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Swift J, Ivanovska IL, Buxboim A, Harada T, Dingal PCDP, Pinter J, Pajerowski JD, Spinler KR, Shin JW, Tewari M, Rehfeldt F, Speicher DW, Discher DE. Nuclear lamin-A scales with tissue stiffness and enhances matrix-directed differentiation. Science 2013; 341:1240104. [PMID: 23990565 DOI: 10.1126/science.1240104] [Citation(s) in RCA: 1295] [Impact Index Per Article: 117.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Tissues can be soft like fat, which bears little stress, or stiff like bone, which sustains high stress, but whether there is a systematic relationship between tissue mechanics and differentiation is unknown. Here, proteomics analyses revealed that levels of the nucleoskeletal protein lamin-A scaled with tissue elasticity, E, as did levels of collagens in the extracellular matrix that determine E. Stem cell differentiation into fat on soft matrix was enhanced by low lamin-A levels, whereas differentiation into bone on stiff matrix was enhanced by high lamin-A levels. Matrix stiffness directly influenced lamin-A protein levels, and, although lamin-A transcription was regulated by the vitamin A/retinoic acid (RA) pathway with broad roles in development, nuclear entry of RA receptors was modulated by lamin-A protein. Tissue stiffness and stress thus increase lamin-A levels, which stabilize the nucleus while also contributing to lineage determination.
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Affiliation(s)
- Joe Swift
- Molecular and Cell Biophysics Laboratory, University of Pennsylvania, Philadelphia, PA 19104, USA
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309
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Li Y, Huang W, Niu L, Umbach DM, Covo S, Li L. Characterization of constitutive CTCF/cohesin loci: a possible role in establishing topological domains in mammalian genomes. BMC Genomics 2013; 14:553. [PMID: 23945083 PMCID: PMC3765723 DOI: 10.1186/1471-2164-14-553] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2013] [Accepted: 07/26/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Recent studies suggested that human/mammalian genomes are divided into large, discrete domains that are units of chromosome organization. CTCF, a CCCTC binding factor, has a diverse role in genome regulation including transcriptional regulation, chromosome-boundary insulation, DNA replication, and chromatin packaging. It remains unclear whether a subset of CTCF binding sites plays a functional role in establishing/maintaining chromatin topological domains. RESULTS We systematically analysed the genomic, transcriptomic and epigenetic profiles of the CTCF binding sites in 56 human cell lines from ENCODE. We identified ~24,000 CTCF sites (referred to as constitutive sites) that were bound in more than 90% of the cell lines. Our analysis revealed: 1) constitutive CTCF loci were located in constitutive open chromatin and often co-localized with constitutive cohesin loci; 2) most constitutive CTCF loci were distant from transcription start sites and lacked CpG islands but were enriched with the full-spectrum CTCF motifs: a recently reported 33/34-mer and two other potentially novel (22/26-mer); 3) more importantly, most constitutive CTCF loci were present in CTCF-mediated chromatin interactions detected by ChIA-PET and these pair-wise interactions occurred predominantly within, but not between, topological domains identified by Hi-C. CONCLUSIONS Our results suggest that the constitutive CTCF sites may play a role in organizing/maintaining the recently identified topological domains that are common across most human cells.
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Affiliation(s)
- Yuanyuan Li
- Biostatistics Branch, National Institute of Environmental Health Sciences, Research Triangle Park, Durham, NC 27709, USA.
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310
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Lund E, Oldenburg AR, Delbarre E, Freberg CT, Duband-Goulet I, Eskeland R, Buendia B, Collas P. Lamin A/C-promoter interactions specify chromatin state-dependent transcription outcomes. Genome Res 2013; 23:1580-9. [PMID: 23861385 PMCID: PMC3787256 DOI: 10.1101/gr.159400.113] [Citation(s) in RCA: 141] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The nuclear lamina is implicated in the organization of the eukaryotic nucleus. Association of nuclear lamins with the genome occurs through large chromatin domains including mostly, but not exclusively, repressed genes. How lamin interactions with regulatory elements modulate gene expression in different cellular contexts is unknown. We show here that in human adipose tissue stem cells, lamin A/C interacts with distinct spatially restricted subpromoter regions, both within and outside peripheral and intra-nuclear lamin-rich domains. These localized interactions are associated with distinct transcriptional outcomes in a manner dependent on local chromatin modifications. Down-regulation of lamin A/C leads to dissociation of lamin A/C from promoters and remodels repressive and permissive histone modifications by enhancing transcriptional permissiveness, but is not sufficient to elicit gene activation. Adipogenic differentiation resets a large number of lamin-genome associations globally and at subpromoter levels and redefines associated transcription outputs. We propose that lamin A/C acts as a modulator of local gene expression outcome through interaction with adjustable sites on promoters, and that these position-dependent transcriptional readouts may be reset upon differentiation.
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Affiliation(s)
- Eivind Lund
- Stem Cell Epigenetics Laboratory, Institute of Basic Medical Sciences, Faculty of Medicine, University of Oslo, and Norwegian Center for Stem Cell Research, Blindern, 0317 Oslo, Norway
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311
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Shapiro JA. How life changes itself: the Read-Write (RW) genome. Phys Life Rev 2013; 10:287-323. [PMID: 23876611 DOI: 10.1016/j.plrev.2013.07.001] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2013] [Accepted: 07/02/2013] [Indexed: 01/06/2023]
Abstract
The genome has traditionally been treated as a Read-Only Memory (ROM) subject to change by copying errors and accidents. In this review, I propose that we need to change that perspective and understand the genome as an intricately formatted Read-Write (RW) data storage system constantly subject to cellular modifications and inscriptions. Cells operate under changing conditions and are continually modifying themselves by genome inscriptions. These inscriptions occur over three distinct time-scales (cell reproduction, multicellular development and evolutionary change) and involve a variety of different processes at each time scale (forming nucleoprotein complexes, epigenetic formatting and changes in DNA sequence structure). Research dating back to the 1930s has shown that genetic change is the result of cell-mediated processes, not simply accidents or damage to the DNA. This cell-active view of genome change applies to all scales of DNA sequence variation, from point mutations to large-scale genome rearrangements and whole genome duplications (WGDs). This conceptual change to active cell inscriptions controlling RW genome functions has profound implications for all areas of the life sciences.
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Affiliation(s)
- James A Shapiro
- Dept. of Biochemistry and Molecular Biology, University of Chicago, GCIS W123B, 979 E. 57th Street, Chicago, IL 60637, USA. http://www.huffingtonpost.com/james-a-shapiro
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312
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Ritland Politz JC, Scalzo D, Groudine M. Something silent this way forms: the functional organization of the repressive nuclear compartment. Annu Rev Cell Dev Biol 2013; 29:241-70. [PMID: 23834025 PMCID: PMC3999972 DOI: 10.1146/annurev-cellbio-101512-122317] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The repressive compartment of the nucleus is comprised primarily of telomeric and centromeric regions, the silent portion of ribosomal RNA genes, the majority of transposable element repeats, and facultatively repressed genes specific to different cell types. This compartment localizes into three main regions: the peripheral heterochromatin, perinucleolar heterochromatin, and pericentromeric heterochromatin. Both chromatin remodeling proteins and transcription of noncoding RNAs are involved in maintenance of repression in these compartments. Global reorganization of the repressive compartment occurs at each cell division, during early development, and during terminal differentiation. Differential action of chromatin remodeling complexes and boundary element looping activities are involved in mediating these organizational changes. We discuss the evidence that heterochromatin formation and compartmentalization may drive nuclear organization.
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Affiliation(s)
| | - David Scalzo
- Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109
| | - Mark Groudine
- Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109
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313
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Abstract
Cancer arises as a consequence of cumulative disruptions to cellular growth control with Darwinian selection for those heritable changes that provide the greatest clonal advantage. These traits can be acquired and stably maintained by either genetic or epigenetic means. Here, we explore the ways in which alterations in the genome and epigenome influence each other and cooperate to promote oncogenic transformation. Disruption of epigenomic control is pervasive in malignancy and can be classified as an enabling characteristic of cancer cells, akin to genome instability and mutation.
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Affiliation(s)
- Hui Shen
- USC Epigenome Center, University of Southern California, Room G511B, 1450 Biggy Street, Los Angeles, CA 90089-9061, USA
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314
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Abstract
Spatiotemporal changes in nuclear lamina composition underlie cell-type-specific chromatin organization and cell fate, suggesting that the lamina forms a dynamic framework critical for genome function, cellular identity, and developmental potential.
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315
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Abstract
The architecture of interphase chromosomes is important for the regulation of gene expression and genome maintenance. Chromosomes are linearly segmented into hundreds of domains with different protein compositions. Furthermore, the spatial organization of chromosomes is nonrandom and is characterized by many local and long-range contacts among genes and other sequence elements. A variety of genome-wide mapping techniques have made it possible to chart these properties at high resolution. Combined with microscopy and computational modeling, the results begin to yield a more coherent picture that integrates linear and three-dimensional (3D) views of chromosome organization in relation to gene regulation and other nuclear functions.
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316
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Kind J, Pagie L, Ortabozkoyun H, Boyle S, de Vries SS, Janssen H, Amendola M, Nolen LD, Bickmore WA, van Steensel B. Single-cell dynamics of genome-nuclear lamina interactions. Cell 2013; 153:178-92. [PMID: 23523135 DOI: 10.1016/j.cell.2013.02.028] [Citation(s) in RCA: 473] [Impact Index Per Article: 43.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2012] [Revised: 12/17/2012] [Accepted: 02/05/2013] [Indexed: 12/15/2022]
Abstract
The nuclear lamina (NL) interacts with hundreds of large genomic regions termed lamina associated domains (LADs). The dynamics of these interactions and the relation to epigenetic modifications are poorly understood. We visualized the fate of LADs in single cells using a "molecular contact memory" approach. In each nucleus, only ~30% of LADs are positioned at the periphery; these LADs are in intermittent molecular contact with the NL but remain constrained to the periphery. Upon mitosis, LAD positioning is not detectably inherited but instead is stochastically reshuffled. Contact of individual LADs with the NL is linked to transcriptional repression and H3K9 dimethylation in single cells. Furthermore, we identify the H3K9 methyltransferase G9a as a regulator of NL contacts. Collectively, these results highlight principles of the dynamic spatial architecture of chromosomes in relation to gene regulation.
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Affiliation(s)
- Jop Kind
- Division of Gene Regulation, Netherlands Cancer Institute, Amsterdam, 1066 CX, The Netherlands.
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317
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Sharma R, Meister P. Nuclear organization in the nematode C. elegans. Curr Opin Cell Biol 2013; 25:395-402. [PMID: 23481208 DOI: 10.1016/j.ceb.2013.02.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2012] [Accepted: 02/05/2013] [Indexed: 11/30/2022]
Abstract
With its invariant cell lineage, easy genetics and small genome, the nematode Caenorhabditis elegans has emerged as one of the prime models in developmental biology over the last 50 years. Surprisingly however, until a decade ago very little was known about nuclear organization in worms, even though it is an ideal model system to explore the link between nuclear organization and cell fate determination. Here, we review the latest findings that exploit the repertoire of genetic tools developed in worms, leading to the identification of important sequences and signals governing the changes in chromatin tridimensional architecture. We also highlight parallels and differences to other model systems.
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Affiliation(s)
- Rahul Sharma
- Cell Fate and Nuclear Organization, Institute of Cell Biology, University of Bern, CH-3012 Bern, Switzerland
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318
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Abstract
The genome is dynamically organized in the nuclear space in a manner that reflects and influences nuclear functions. Developmental processes that govern the formation and maintenance of epigenetic memories are also tightly linked to adaptive changes in the physical and functional landscape of the nuclear architecture. Biological and biophysical principles governing the three-dimensional folding of chromatin are therefore central to our understanding of epigenetic regulation during adaptive responses and in complex diseases, such as cancer. Accumulating evidence points to the direction that global alterations in nuclear architecture and chromatin folding conspire with unstable epigenetic states of the primary chromatin fiber to drive the phenotypic plasticity of cancer cells.
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Affiliation(s)
- Anita Göndör
- Microbiology, Tumor and Cell Biology, Karolinska Institutet, Nobels väg 16, KI Solna Campus, Box 280, SE-171 77 Stockholm, Sweden.
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Reddy KL, Feinberg AP. Higher order chromatin organization in cancer. Semin Cancer Biol 2012; 23:109-15. [PMID: 23266653 DOI: 10.1016/j.semcancer.2012.12.001] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2012] [Accepted: 12/12/2012] [Indexed: 01/30/2023]
Abstract
In spite of our increased understanding of how genomes are dysregulated in cancer and a plethora of molecular diagnostic tools, the front line and 'gold standard' detection of cancer remains the pathologist's detection of gross changes in cellular and tissue structure, most strikingly nuclear dis-organization. In fact, for over 140 years it has been noted that nuclear morphology is often disrupted in cancer. Even today, nuclear morphology measures include nuclear size, shape, DNA content (ploidy) and 'chromatin organization'. Given the importance of nuclear shape to diagnoses of cancer phenotypes, it is surprising and frustrating that we currently lack a detailed understanding to explain these changes and how they might arise and relate to molecular events in the cell. It is an implicit hypothesis that perturbation of chromatin and epigenetic signatures may lead to alterations in nuclear structure (or vice versa) and that these perturbations lie at the heart of cancer genesis. In this review, we attempt to synthesize research leading to our current understanding on how chromatin interactions at the nuclear lamina, epigenetic modulation and gene regulation may intersect in cancer and offer a perspective on critical experiments that would help clarify how nuclear architecture may contribute to the cancerous phenotype. We also discuss the historical understanding of nuclear structure in normal cells and as a diagnostic in cancer.
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Affiliation(s)
- Karen L Reddy
- Center for Epigenetics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, United States.
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