1
|
He J, Huo X, Pei G, Jia Z, Yan Y, Yu J, Qu H, Xie Y, Yuan J, Zheng Y, Hu Y, Shi M, You K, Li T, Ma T, Zhang MQ, Ding S, Li P, Li Y. Dual-role transcription factors stabilize intermediate expression levels. Cell 2024; 187:2746-2766.e25. [PMID: 38631355 DOI: 10.1016/j.cell.2024.03.023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Revised: 12/08/2023] [Accepted: 03/18/2024] [Indexed: 04/19/2024]
Abstract
Precise control of gene expression levels is essential for normal cell functions, yet how they are defined and tightly maintained, particularly at intermediate levels, remains elusive. Here, using a series of newly developed sequencing, imaging, and functional assays, we uncover a class of transcription factors with dual roles as activators and repressors, referred to as condensate-forming level-regulating dual-action transcription factors (TFs). They reduce high expression but increase low expression to achieve stable intermediate levels. Dual-action TFs directly exert activating and repressing functions via condensate-forming domains that compartmentalize core transcriptional unit selectively. Clinically relevant mutations in these domains, which are linked to a range of developmental disorders, impair condensate selectivity and dual-action TF activity. These results collectively address a fundamental question in expression regulation and demonstrate the potential of level-regulating dual-action TFs as powerful effectors for engineering controlled expression levels.
Collapse
Affiliation(s)
- Jinnan He
- The IDG/McGovern Institute for Brain Research, MOE Key Laboratory of Bioinformatics, State Key Lab of Molecular Oncology, Center for Synthetic and Systems Biology, Tsinghua University, Beijing 100084, China; School of Pharmaceutical Sciences, Tsinghua University, Beijing 100084, China
| | - Xiangru Huo
- The IDG/McGovern Institute for Brain Research, MOE Key Laboratory of Bioinformatics, State Key Lab of Molecular Oncology, Center for Synthetic and Systems Biology, Tsinghua University, Beijing 100084, China; School of Pharmaceutical Sciences, Tsinghua University, Beijing 100084, China
| | - Gaofeng Pei
- State Key Laboratory of Membrane Biology, Frontier Research Center for Biological Structure, School of Life Sciences, Tsinghua University, Beijing 100084, China; Tsinghua University-Peking University Joint Center for Life Sciences, Beijing 100084, China
| | - Zeran Jia
- The IDG/McGovern Institute for Brain Research, MOE Key Laboratory of Bioinformatics, State Key Lab of Molecular Oncology, Center for Synthetic and Systems Biology, Tsinghua University, Beijing 100084, China; School of Pharmaceutical Sciences, Tsinghua University, Beijing 100084, China
| | - Yiming Yan
- The IDG/McGovern Institute for Brain Research, MOE Key Laboratory of Bioinformatics, State Key Lab of Molecular Oncology, Center for Synthetic and Systems Biology, Tsinghua University, Beijing 100084, China; School of Pharmaceutical Sciences, Tsinghua University, Beijing 100084, China
| | - Jiawei Yu
- The IDG/McGovern Institute for Brain Research, MOE Key Laboratory of Bioinformatics, State Key Lab of Molecular Oncology, Center for Synthetic and Systems Biology, Tsinghua University, Beijing 100084, China; School of Pharmaceutical Sciences, Tsinghua University, Beijing 100084, China
| | - Haozhi Qu
- The IDG/McGovern Institute for Brain Research, MOE Key Laboratory of Bioinformatics, State Key Lab of Molecular Oncology, Center for Synthetic and Systems Biology, Tsinghua University, Beijing 100084, China; School of Pharmaceutical Sciences, Tsinghua University, Beijing 100084, China
| | - Yunxin Xie
- The IDG/McGovern Institute for Brain Research, MOE Key Laboratory of Bioinformatics, State Key Lab of Molecular Oncology, Center for Synthetic and Systems Biology, Tsinghua University, Beijing 100084, China; School of Pharmaceutical Sciences, Tsinghua University, Beijing 100084, China
| | - Junsong Yuan
- The IDG/McGovern Institute for Brain Research, MOE Key Laboratory of Bioinformatics, State Key Lab of Molecular Oncology, Center for Synthetic and Systems Biology, Tsinghua University, Beijing 100084, China; School of Pharmaceutical Sciences, Tsinghua University, Beijing 100084, China
| | - Yuan Zheng
- The IDG/McGovern Institute for Brain Research, MOE Key Laboratory of Bioinformatics, State Key Lab of Molecular Oncology, Center for Synthetic and Systems Biology, Tsinghua University, Beijing 100084, China; School of Pharmaceutical Sciences, Tsinghua University, Beijing 100084, China
| | - Yanyan Hu
- School of Pharmaceutical Sciences, Tsinghua University, Beijing 100084, China; Tsinghua University-Peking University Joint Center for Life Sciences, Beijing 100084, China
| | - Minglei Shi
- Bioinformatics Division, National Research Center for Information Science and Technology, School of Medicine, Tsinghua University, Beijing 100084, China
| | - Kaiqiang You
- Department of Biomedical Informatics, School of Basic Medical Sciences, Peking University Health Science Center, Beijing 100191, China
| | - Tingting Li
- Department of Biomedical Informatics, School of Basic Medical Sciences, Peking University Health Science Center, Beijing 100191, China
| | - Tianhua Ma
- School of Pharmaceutical Sciences, Tsinghua University, Beijing 100084, China; Tsinghua University-Peking University Joint Center for Life Sciences, Beijing 100084, China
| | - Michael Q Zhang
- Bioinformatics Division, National Research Center for Information Science and Technology, School of Medicine, Tsinghua University, Beijing 100084, China; Department of Biological Sciences, Center for Systems Biology, The University of Texas, Dallas, TX 75080-3021, USA
| | - Sheng Ding
- School of Pharmaceutical Sciences, Tsinghua University, Beijing 100084, China; Tsinghua University-Peking University Joint Center for Life Sciences, Beijing 100084, China
| | - Pilong Li
- State Key Laboratory of Membrane Biology, Frontier Research Center for Biological Structure, School of Life Sciences, Tsinghua University, Beijing 100084, China; Tsinghua University-Peking University Joint Center for Life Sciences, Beijing 100084, China.
| | - Yinqing Li
- The IDG/McGovern Institute for Brain Research, MOE Key Laboratory of Bioinformatics, State Key Lab of Molecular Oncology, Center for Synthetic and Systems Biology, Tsinghua University, Beijing 100084, China; School of Pharmaceutical Sciences, Tsinghua University, Beijing 100084, China.
| |
Collapse
|
2
|
Knoch TA. How Genomes Emerge, Function, and Evolve: Living Systems Emergence-Genotype-Phenotype-Multilism-Genome/Systems Ecology. Results Probl Cell Differ 2022; 70:103-156. [PMID: 36348106 DOI: 10.1007/978-3-031-06573-6_4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
What holds together the world in its innermost, what life is, how it emerges, functions, and evolves, has not only been an epic matter of endless romantic sunset poetry and philosophy, but also manifests explicitly in its perhaps most central organization unit-genomes. Their 3D architecture and dynamics, including the interaction networks of regulatory elements, obviously co-evolved as inseparable systems allowing the physical storage, expression, and replication of genetic information. Since we were able to fill finally the much-debated centennial gaps in their 3D architecture and dynamics, now entire new perspectives open beyond epigenetics reaching as far as a general understanding of living systems: besides the previously known DNA double helix and nucleosome structure, the latter compact into a chromatin quasi-fibre folded into stable loops forming stable multi-loop aggregates/rosettes connected by linkers, creating hence the again already known chromosome arms and entire chromosomes forming the cell nucleus. Instantly and for the first time this leads now to a consistent and cross-proven systems statistical mechanics genomics framework elucidating genome intrinsic function and regulation including various components. It balances stability/flexibility ensuring genome integrity, enabling expression/regulation of genetic information, as well as genome replication/spread. Furthermore, genotype and phenotype are multiplisticly entangled being evolutionarily the outcome of both Darwinian natural selection and Lamarckian self-referenced manipulation-all embedded in even broader genome ecology (autopoietic) i(!)n- and environmental scopes. This allows formulating new meta-level functional semantics of genomics, i.e. notions as communication of genes, genomes, and information networks, architectural and dynamic spaces for creativity and innovation, or genomes as central geno-/phenotype entanglements. Beyond and most fundamentally, the paradoxical-seeming local equilibrium substance stability in its entity though far from a universal heat-death-like equilibrium is solved, and system irreversibility, time directionality, and thus the emergence of existence are clarified. Consequently, real deep understandings of genomes, life, and complex systems in general appear in evolutionary perspectives as well as from systems analyses, via system damage/disease (its repair/cure and manipulation) as far as the understanding of extraterrestrial life, the de novo creation and thus artificial life, and even the raison d'etre.
Collapse
Affiliation(s)
- Tobias A Knoch
- Biophysical Genomics, TAKnoch Joined Operations Administrative Office, Mannheim, Germany.
- Human Ecology and Complex Systems, German Society for Human Ecology (DGH), TAKnoch Joined Operations Administrative Office, Mannheim, Germany.
- TAK Renewable Energy UG, TAKnoch Joined Operations Administrative Office, Mannheim, Germany.
| |
Collapse
|
3
|
Knoch TA. Simulation of Different Three-Dimensional Models of Whole Interphase Nuclei Compared to Experiments - A Consistent Scale-Bridging Simulation Framework for Genome Organization. Results Probl Cell Differ 2022; 70:495-549. [PMID: 36348120 DOI: 10.1007/978-3-031-06573-6_18] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
The three-dimensional architecture of chromosomes, their arrangement, and dynamics within cell nuclei are still subject of debate. Obviously, the function of genomes-the storage, replication, and transcription of genetic information-has closely coevolved with this architecture and its dynamics, and hence are closely connected. In this work a scale-bridging framework investigates how of the 30 nm chromatin fibre organizes into chromosomes including their arrangement and morphology in the simulation of whole nuclei. Therefore, mainly two different topologies were simulated with corresponding parameter variations and comparing them to experiments: The Multi-Loop-Subcompartment (MLS) model, in which (stable) small loops form (stable) rosettes, connected by chromatin linkers, and the Random-Walk/Giant-Loop (RW/GL) model, in which large loops are attached to a flexible non-protein backbone, were simulated for various loop and linker sizes. The 30 nm chromatin fibre was modelled as a polymer chain with stretching, bending and excluded volume interactions. A spherical boundary potential simulated the confinement to nuclei with different radii. Simulated annealing and Brownian Dynamics methods were applied in a four-step decondensation procedure to generate from metaphase decondensated interphase configurations at thermodynamical equilibrium. Both the MLS and the RW/GL models form chromosome territories, with different morphologies: The MLS rosettes result in distinct subchromosomal domains visible in electron and confocal laser scanning microscopic images. In contrast, the big RW/GL loops lead to a mostly homogeneous chromatin distribution. Even small changes of the model parameters induced significant rearrangements of the chromatin morphology. The low overlap of chromosomes, arms, and subchromosomal domains observed in experiments agrees only with the MLS model. The chromatin density distribution in CLSM image stacks reveals a bimodal behaviour in agreement with recent experiments. Combination of these results with a variety of (spatial distance) measurements favour an MLS like model with loops and linkers of 63 to 126 kbp. The predicted large spaces between the chromatin fibres allow typically sized biological molecules to reach nearly every location in the nucleus by moderately obstructed diffusion and is in disagreement with the much simplified assumption that defined channels between territories for molecular transport as in the Interchromosomal Domain (ICD) hypothesis exist and are necessary for transport. All this is also in agreement with recent selective high-resolution chromosome interaction capture (T2C) experiments, the scaling behaviour of the DNA sequence, the dynamics of the chromatin fibre, the diffusion of molecules, and other measurements. Also all other chromosome topologies can in principle be excluded. In summary, polymer simulations of whole nuclei compared to experimental data not only clearly favour only a stable loop aggregate/rosette like genome architecture whose local topology is tightly connected to the global morphology and dynamics of the cell nucleus and hence can be used for understanding genome organization also in respect to diagnosis and treatment. This is in agreement with and also leads to a general novel framework of genome emergence, function, and evolution.
Collapse
Affiliation(s)
- Tobias A Knoch
- Biophysical Genomics, TAKnoch Joined Operations Administrative Office, Mannheim, Germany.
- Human Ecology and Complex Systems, German Society for Human Ecology (DGH), TAKnoch Joined Operations Administrative Office, Mannheim, Germany.
- TAK Renewable Energy UG, TAKnoch Joined Operations Administrative Office, Mannheim, Germany.
| |
Collapse
|
4
|
Maslova A, Krasikova A. FISH Going Meso-Scale: A Microscopic Search for Chromatin Domains. Front Cell Dev Biol 2021; 9:753097. [PMID: 34805161 PMCID: PMC8597843 DOI: 10.3389/fcell.2021.753097] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Accepted: 10/08/2021] [Indexed: 12/14/2022] Open
Abstract
The intimate relationships between genome structure and function direct efforts toward deciphering three-dimensional chromatin organization within the interphase nuclei at different genomic length scales. For decades, major insights into chromatin structure at the level of large-scale euchromatin and heterochromatin compartments, chromosome territories, and subchromosomal regions resulted from the evolution of light microscopy and fluorescence in situ hybridization. Studies of nanoscale nucleosomal chromatin organization benefited from a variety of electron microscopy techniques. Recent breakthroughs in the investigation of mesoscale chromatin structures have emerged from chromatin conformation capture methods (C-methods). Chromatin has been found to form hierarchical domains with high frequency of local interactions from loop domains to topologically associating domains and compartments. During the last decade, advances in super-resolution light microscopy made these levels of chromatin folding amenable for microscopic examination. Here we are reviewing recent developments in FISH-based approaches for detection, quantitative measurements, and validation of contact chromatin domains deduced from C-based data. We specifically focus on the design and application of Oligopaint probes, which marked the latest progress in the imaging of chromatin domains. Vivid examples of chromatin domain FISH-visualization by means of conventional, super-resolution light and electron microscopy in different model organisms are provided.
Collapse
Affiliation(s)
| | - Alla Krasikova
- Laboratory of Nuclear Structure and Dynamics, Cytology and Histology Department, Saint Petersburg State University, Saint Petersburg, Russia
| |
Collapse
|
5
|
McNamara G, Difilippantonio M, Ried T, Bieber FR. Microscopy and Image Analysis. ACTA ACUST UNITED AC 2018; 94:4.4.1-4.4.89. [DOI: 10.1002/cphg.42] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
| | - Michael Difilippantonio
- Division of Cancer Treatment and Diagnosis National Cancer Institute, National Institutes of Health Bethesda Maryland
| | - Thomas Ried
- Section of Cancer Genomics Genetics Branch Center for Cancer Research National Cancer Institute, National Institutes of Health Bethesda Maryland
| | | |
Collapse
|
6
|
Fabre PJ, Leleu M, Mormann BH, Lopez-Delisle L, Noordermeer D, Beccari L, Duboule D. Large scale genomic reorganization of topological domains at the HoxD locus. Genome Biol 2017; 18:149. [PMID: 28784160 PMCID: PMC5547506 DOI: 10.1186/s13059-017-1278-z] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Accepted: 07/14/2017] [Indexed: 01/22/2023] Open
Abstract
BACKGROUND The transcriptional activation of HoxD genes during mammalian limb development involves dynamic interactions with two topologically associating domains (TADs) flanking the HoxD cluster. In particular, the activation of the most posterior HoxD genes in developing digits is controlled by regulatory elements located in the centromeric TAD (C-DOM) through long-range contacts. RESULTS To assess the structure-function relationships underlying such interactions, we measured compaction levels and TAD discreteness using a combination of chromosome conformation capture (4C-seq) and DNA FISH. We assessed the robustness of the TAD architecture by using a series of genomic deletions and inversions that impact the integrity of this chromatin domain and that remodel long-range contacts. We report multi-partite associations between HoxD genes and up to three enhancers. We find that the loss of native chromatin topology leads to the remodeling of TAD structure following distinct parameters. CONCLUSIONS Our results reveal that the recomposition of TAD architectures after large genomic re-arrangements is dependent on a boundary-selection mechanism in which CTCF mediates the gating of long-range contacts in combination with genomic distance and sequence specificity. Accordingly, the building of a recomposed TAD at this locus depends on distinct functional and constitutive parameters.
Collapse
Affiliation(s)
- Pierre J Fabre
- School of Life Sciences, Ecole Polytechnique Fédérale, 1015, Lausanne, Switzerland
| | - Marion Leleu
- School of Life Sciences, Ecole Polytechnique Fédérale, 1015, Lausanne, Switzerland
| | - Benjamin H Mormann
- School of Life Sciences, Ecole Polytechnique Fédérale, 1015, Lausanne, Switzerland
| | | | - Daan Noordermeer
- School of Life Sciences, Ecole Polytechnique Fédérale, 1015, Lausanne, Switzerland.,Present address: Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-sud, University Paris-Saclay, 1 Avenue de la terrasse, 91198, Gif-sur-Yvette, France
| | - Leonardo Beccari
- Department of Genetics and Evolution, University of Geneva, 1211, Geneva 4, Switzerland
| | - Denis Duboule
- School of Life Sciences, Ecole Polytechnique Fédérale, 1015, Lausanne, Switzerland. .,Department of Genetics and Evolution, University of Geneva, 1211, Geneva 4, Switzerland.
| |
Collapse
|
7
|
How does chromatin package DNA within nucleus and regulate gene expression? Int J Biol Macromol 2017; 101:862-881. [PMID: 28366861 DOI: 10.1016/j.ijbiomac.2017.03.165] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Revised: 03/28/2017] [Accepted: 03/28/2017] [Indexed: 01/26/2023]
Abstract
The human body is made up of 60 trillion cells, each cell containing 2 millions of genomic DNA in its nucleus. How is this genomic deoxyribonucleic acid [DNA] organised into nuclei? Around 1880, W. Flemming discovered a nuclear substance that was clearly visible on staining under primitive light microscopes and named it 'chromatin'; this is now thought to be the basic unit of genomic DNA organization. Since long before DNA was known to carry genetic information, chromatin has fascinated biologists. DNA has a negatively charged phosphate backbone that produces electrostatic repulsion between adjacent DNA regions, making it difficult for DNA to fold upon itself. In this article, we will try to shed light on how does chromatin package DNA within nucleus and regulate gene expression?
Collapse
|
8
|
Knoch TA, Wachsmuth M, Kepper N, Lesnussa M, Abuseiris A, Ali Imam AM, Kolovos P, Zuin J, Kockx CEM, Brouwer RWW, van de Werken HJG, van IJcken WFJ, Wendt KS, Grosveld FG. The detailed 3D multi-loop aggregate/rosette chromatin architecture and functional dynamic organization of the human and mouse genomes. Epigenetics Chromatin 2016; 9:58. [PMID: 28035242 PMCID: PMC5192698 DOI: 10.1186/s13072-016-0089-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2016] [Accepted: 09/01/2016] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND The dynamic three-dimensional chromatin architecture of genomes and its co-evolutionary connection to its function-the storage, expression, and replication of genetic information-is still one of the central issues in biology. Here, we describe the much debated 3D architecture of the human and mouse genomes from the nucleosomal to the megabase pair level by a novel approach combining selective high-throughput high-resolution chromosomal interaction capture (T2C), polymer simulations, and scaling analysis of the 3D architecture and the DNA sequence. RESULTS The genome is compacted into a chromatin quasi-fibre with ~5 ± 1 nucleosomes/11 nm, folded into stable ~30-100 kbp loops forming stable loop aggregates/rosettes connected by similar sized linkers. Minor but significant variations in the architecture are seen between cell types and functional states. The architecture and the DNA sequence show very similar fine-structured multi-scaling behaviour confirming their co-evolution and the above. CONCLUSIONS This architecture, its dynamics, and accessibility, balance stability and flexibility ensuring genome integrity and variation enabling gene expression/regulation by self-organization of (in)active units already in proximity. Our results agree with the heuristics of the field and allow "architectural sequencing" at a genome mechanics level to understand the inseparable systems genomic properties.
Collapse
Affiliation(s)
- Tobias A. Knoch
- Biophysical Genomics, Department of Cell Biology and Genetics, Erasmus MC, Wytemaweg 80, 3015 CN Rotterdam, The Netherlands
| | - Malte Wachsmuth
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Meyerhofstr. 1, 69117 Heidelberg, Germany
| | - Nick Kepper
- Biophysical Genomics, Department of Cell Biology and Genetics, Erasmus MC, Wytemaweg 80, 3015 CN Rotterdam, The Netherlands
- Genome Organization and Function, BioQuant and German Cancer Research Center, Im Neuenheimer Feld 267, 69120 Heidelberg, Germany
| | - Michael Lesnussa
- Biophysical Genomics, Department of Cell Biology and Genetics, Erasmus MC, Wytemaweg 80, 3015 CN Rotterdam, The Netherlands
| | - Anis Abuseiris
- Biophysical Genomics, Department of Cell Biology and Genetics, Erasmus MC, Wytemaweg 80, 3015 CN Rotterdam, The Netherlands
| | - A. M. Ali Imam
- Biophysical Genomics, Department of Cell Biology and Genetics, Erasmus MC, Wytemaweg 80, 3015 CN Rotterdam, The Netherlands
- Cell Biology, Department Cell Biology and Genetics, Erasmus MC, Dr. Molewaterplein 50, 3015 GE Rotterdam, The Netherlands
| | - Petros Kolovos
- Biophysical Genomics, Department of Cell Biology and Genetics, Erasmus MC, Wytemaweg 80, 3015 CN Rotterdam, The Netherlands
- Cell Biology, Department Cell Biology and Genetics, Erasmus MC, Dr. Molewaterplein 50, 3015 GE Rotterdam, The Netherlands
| | - Jessica Zuin
- Cohesin in Chromatin Structure and Gene Regulation, Department of Cell Biology and Genetics, Erasmus MC, Dr. Molewaterplein 50, 3015 GE Rotterdam, The Netherlands
| | - Christel E. M. Kockx
- Center for Biomics, Department of Cell Biology and Genetics, Erasmus MC, Dr. Molewaterplein 50, 3015 GE Rotterdam, The Netherlands
| | - Rutger W. W. Brouwer
- Center for Biomics, Department of Cell Biology and Genetics, Erasmus MC, Dr. Molewaterplein 50, 3015 GE Rotterdam, The Netherlands
| | - Harmen J. G. van de Werken
- Cell Biology, Department Cell Biology and Genetics, Erasmus MC, Dr. Molewaterplein 50, 3015 GE Rotterdam, The Netherlands
| | - Wilfred F. J. van IJcken
- Center for Biomics, Department of Cell Biology and Genetics, Erasmus MC, Dr. Molewaterplein 50, 3015 GE Rotterdam, The Netherlands
| | - Kerstin S. Wendt
- Cohesin in Chromatin Structure and Gene Regulation, Department of Cell Biology and Genetics, Erasmus MC, Dr. Molewaterplein 50, 3015 GE Rotterdam, The Netherlands
| | - Frank G. Grosveld
- Cell Biology, Department Cell Biology and Genetics, Erasmus MC, Dr. Molewaterplein 50, 3015 GE Rotterdam, The Netherlands
| |
Collapse
|
9
|
Dickerson D, Gierliński M, Singh V, Kitamura E, Ball G, Tanaka TU, Owen-Hughes T. High resolution imaging reveals heterogeneity in chromatin states between cells that is not inherited through cell division. BMC Cell Biol 2016; 17:33. [PMID: 27609610 PMCID: PMC5016949 DOI: 10.1186/s12860-016-0111-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Accepted: 08/25/2016] [Indexed: 01/23/2023] Open
Abstract
Background Genomes of eukaryotes exist as chromatin, and it is known that different chromatin states can influence gene regulation. Chromatin is not a static structure, but is known to be dynamic and vary between cells. In order to monitor the organisation of chromatin in live cells we have engineered fluorescent fusion proteins which recognize specific operator sequences to tag pairs of syntenic gene loci. The separation of these loci was then tracked in three dimensions over time using fluorescence microscopy. Results We established a work flow for measuring the distance between two fluorescently tagged, syntenic gene loci with a mean measurement error of 63 nm. In general, physical separation was observed to increase with increasing genomic separations. However, the extent to which chromatin is compressed varies for different genomic regions. No correlation was observed between compaction and the distribution of chromatin markers from genomic datasets or with contacts identified using capture based approaches. Variation in spatial separation was also observed within cells over time and between cells. Differences in the conformation of individual loci can persist for minutes in individual cells. Separation of reporter loci was found to be similar in related and unrelated daughter cell pairs. Conclusions The directly observed physical separation of reporter loci in live cells is highly dynamic both over time and from cell to cell. However, consistent differences in separation are observed over some chromosomal regions that do not correlate with factors known to influence chromatin states. We conclude that as yet unidentified parameters influence chromatin configuration. We also find that while heterogeneity in chromatin states can be maintained for minutes between cells, it is not inherited through cell division. This may contribute to cell-to-cell transcriptional heterogeneity. Electronic supplementary material The online version of this article (doi:10.1186/s12860-016-0111-y) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- David Dickerson
- Centre for Gene Regulation and Expression, College of Life Sciences, University of Dundee, Dundee, DD1 5EH, UK
| | - Marek Gierliński
- Centre for Gene Regulation and Expression, College of Life Sciences, University of Dundee, Dundee, DD1 5EH, UK
| | - Vijender Singh
- Centre for Gene Regulation and Expression, College of Life Sciences, University of Dundee, Dundee, DD1 5EH, UK
| | - Etsushi Kitamura
- Centre for Gene Regulation and Expression, College of Life Sciences, University of Dundee, Dundee, DD1 5EH, UK
| | - Graeme Ball
- Centre for Gene Regulation and Expression, College of Life Sciences, University of Dundee, Dundee, DD1 5EH, UK
| | - Tomoyuki U Tanaka
- Centre for Gene Regulation and Expression, College of Life Sciences, University of Dundee, Dundee, DD1 5EH, UK
| | - Tom Owen-Hughes
- Centre for Gene Regulation and Expression, College of Life Sciences, University of Dundee, Dundee, DD1 5EH, UK. .,Wellcome Trust Building, University of Dundee, Dow Street, Dundee, DD1 5EH, UK.
| |
Collapse
|
10
|
Williamson I, Berlivet S, Eskeland R, Boyle S, Illingworth RS, Paquette D, Dostie J, Bickmore WA. Spatial genome organization: contrasting views from chromosome conformation capture and fluorescence in situ hybridization. Genes Dev 2014; 28:2778-91. [PMID: 25512564 PMCID: PMC4265680 DOI: 10.1101/gad.251694.114] [Citation(s) in RCA: 190] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2014] [Accepted: 10/30/2014] [Indexed: 01/28/2023]
Abstract
Although important for gene regulation, most studies of genome organization use either fluorescence in situ hybridization (FISH) or chromosome conformation capture (3C) methods. FISH directly visualizes the spatial relationship of sequences but is usually applied to a few loci at a time. The frequency at which sequences are ligated together by formaldehyde cross-linking can be measured genome-wide by 3C methods, with higher frequencies thought to reflect shorter distances. FISH and 3C should therefore give the same views of genome organization, but this has not been tested extensively. We investigated the murine HoxD locus with 3C carbon copy (5C) and FISH in different developmental and activity states and in the presence or absence of epigenetic regulators. We identified situations in which the two data sets are concordant but found other conditions under which chromatin topographies extrapolated from 5C or FISH data are not compatible. We suggest that products captured by 3C do not always reflect spatial proximity, with ligation occurring between sequences located hundreds of nanometers apart, influenced by nuclear environment and chromatin composition. We conclude that results obtained at high resolution with either 3C methods or FISH alone must be interpreted with caution and that views about genome organization should be validated by independent methods.
Collapse
Affiliation(s)
- Iain Williamson
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh EH4 2XU, United Kingdom
| | - Soizik Berlivet
- Department of Biochemistry, Goodman Cancer Research Center, McGill University, Montréal, Québec H3G1Y6, Canada
| | - Ragnhild Eskeland
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh EH4 2XU, United Kingdom
| | - Shelagh Boyle
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh EH4 2XU, United Kingdom
| | - Robert S Illingworth
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh EH4 2XU, United Kingdom
| | | | | | - Wendy A Bickmore
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh EH4 2XU, United Kingdom;
| |
Collapse
|
11
|
Andreadis C, Nikolaou C, Fragiadakis GS, Tsiliki G, Alexandraki D. Rad9 interacts with Aft1 to facilitate genome surveillance in fragile genomic sites under non-DNA damage-inducing conditions in S. cerevisiae. Nucleic Acids Res 2014; 42:12650-67. [PMID: 25300486 PMCID: PMC4227768 DOI: 10.1093/nar/gku915] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022] Open
Abstract
DNA damage response and repair proteins are centrally involved in genome maintenance pathways. Yet, little is known about their functional role under non-DNA damage-inducing conditions. Here we show that Rad9 checkpoint protein, known to mediate the damage signal from upstream to downstream essential kinases, interacts with Aft1 transcription factor in the budding yeast. Aft1 regulates iron homeostasis and is also involved in genome integrity having additional iron-independent functions. Using genome-wide expression and chromatin immunoprecipitation approaches, we found Rad9 to be recruited to 16% of the yeast genes, often related to cellular growth and metabolism, while affecting the transcription of ∼2% of the coding genome in the absence of exogenously induced DNA damage. Importantly, Rad9 is recruited to fragile genomic regions (transcriptionally active, GC rich, centromeres, meiotic recombination hotspots and retrotransposons) non-randomly and in an Aft1-dependent manner. Further analyses revealed substantial genome-wide parallels between Rad9 binding patterns to the genome and major activating histone marks, such as H3K36me, H3K79me and H3K4me. Thus, our findings suggest that Rad9 functions together with Aft1 on DNA damage-prone chromatin to facilitate genome surveillance, thereby ensuring rapid and effective response to possible DNA damage events.
Collapse
Affiliation(s)
- Christos Andreadis
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-HELLAS, Crete 70013, Greece Department of Biology, University of Crete, Crete 70013, Greece
| | | | - George S Fragiadakis
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-HELLAS, Crete 70013, Greece
| | - Georgia Tsiliki
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-HELLAS, Crete 70013, Greece
| | - Despina Alexandraki
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-HELLAS, Crete 70013, Greece Department of Biology, University of Crete, Crete 70013, Greece
| |
Collapse
|
12
|
Nolen LD, Boyle S, Ansari M, Pritchard E, Bickmore WA. Regional chromatin decompaction in Cornelia de Lange syndrome associated with NIPBL disruption can be uncoupled from cohesin and CTCF. Hum Mol Genet 2013; 22:4180-93. [PMID: 23760082 PMCID: PMC3781641 DOI: 10.1093/hmg/ddt265] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2013] [Accepted: 06/03/2013] [Indexed: 01/09/2023] Open
Abstract
Cornelia de Lange syndrome (CdLS) is a developmental disorder caused by mutations in NIPBL, a protein which has functionally been associated with the cohesin complex. Mutations in core cohesin complex components have also been reported in individuals with CdLS-like phenotypes. In addition to its role in sister chromatid cohesion, cohesin is thought to play a role in regulating gene expression during development. The mechanism of this gene regulation remains unclear, but NIPBL and cohesin have been reported to affect long-range chromosomal interactions, both independently and through interactions with CTCF. We used fluorescence in situ hybridization to investigate whether the disruption of NIPBL affects chromosome architecture. We show that cells from CdLS patients exhibit visible chromatin decompaction, that is most pronounced across gene-rich regions of the genome. Cells carrying mutations predicted to have a more severe effect on NIPBL function show more extensive chromatin decompaction than those carrying milder mutations. This cellular phenotype was reproduced in normal cells depleted for NIPBL with siRNA, but was not seen following the knockdown of either the cohesin component SMC3, or CTCF. We conclude that NIPBL has a function in modulating chromatin architecture, particularly for gene-rich areas of the chromosome, that is not dependent on SMC3/cohesin or CTCF, raising the possibility that the aetiology of disorders associated with the mutation of core cohesin components is distinct from that associated with the disruption of NIPBL itself in classical CdLS.
Collapse
Affiliation(s)
| | | | | | | | - Wendy A. Bickmore
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Crewe Road, Edinburgh EH4 2XU, UK
| |
Collapse
|
13
|
Abstract
In vivo, the human genome functions as a complex, folded, three-dimensional chromatin polymer. Understanding how the human genome is spatially organized and folded inside the cell nucleus is therefore central to understanding how genes are regulated in normal development and dysregulated in disease. Established light microscopy-based approaches and more recent molecular chromosome conformation capture methods are now combining to give us unprecedented insight into this fascinating aspect of human genomics.
Collapse
Affiliation(s)
- Wendy A Bickmore
- MRC Human Genetics Unit, MRC Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh EH4 2XU, United Kingdom;
| |
Collapse
|
14
|
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.
Collapse
|
15
|
Borghese B, Barbaux S, Mondon F, Santulli P, Pierre G, Vinci G, Chapron C, Vaiman D. Research resource: genome-wide profiling of methylated promoters in endometriosis reveals a subtelomeric location of hypermethylation. Mol Endocrinol 2010; 24:1872-85. [PMID: 20685852 DOI: 10.1210/me.2010-0160] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Several lines of evidence indicate that endometriosis could be partially due to selective epigenetic deregulations. Promoter hypermethylation of some key genes, such as progesterone receptor and aromatase, has been associated with the silencing of these genes and might contribute to the disease. However, it is unknown whether global alterations in DNA methylation patterns occur in endometriosis and to what extent they are involved in its pathogenesis. We conducted a whole-genome scanning of methylation status in more than 25,000 promoters, using methylated DNA immunoprecipitation with hybridization to promoter microarrays. We detailed the methylation profiles for each subtype of the disease (superficial endometriosis, endometriomas, and deep infiltrating endometriosis) and compared them with the profile obtained for the eutopic endometrium. In line with the current theory of the endometrial origin of endometriosis, the overall methylation profile was highly similar between the endometrium and the lesions. It showed promoter regions consistently hypomethylated or hypermethylated (more than 1.5-times, as compared with endometrium) and others specific to one given subtype. Albeit there was no systematic correlation between promoter methylation and expression of nearby genes, 35 genes had both methylation and expressional alterations in the lesions. These genes, reported here for the first time, might be of interest in the development of endometriosis. In addition, hypermethylated regions were located at the ends of the chromosomes, whereas hypomethylated regions were randomly distributed all along the chromosomes. We postulated that this original observation might participate to the chromosomal stability and protect the endometriotic lesion against malignancy.
Collapse
Affiliation(s)
- Bruno Borghese
- Département Génétique et Développement, Institut Cochin, 24 rue du Faubourg Saint-Jacques, 75014 Paris, France.
| | | | | | | | | | | | | | | |
Collapse
|
16
|
Eskeland R, Leeb M, Grimes GR, Kress C, Boyle S, Sproul D, Gilbert N, Fan Y, Skoultchi AI, Wutz A, Bickmore WA. Ring1B compacts chromatin structure and represses gene expression independent of histone ubiquitination. Mol Cell 2010; 38:452-64. [PMID: 20471950 DOI: 10.1016/j.molcel.2010.02.032] [Citation(s) in RCA: 420] [Impact Index Per Article: 30.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2009] [Revised: 11/04/2009] [Accepted: 02/15/2010] [Indexed: 10/19/2022]
Abstract
How polycomb group proteins repress gene expression in vivo is not known. While histone-modifying activities of the polycomb repressive complexes (PRCs) have been studied extensively, in vitro data have suggested a direct activity of the PRC1 complex in compacting chromatin. Here, we investigate higher-order chromatin compaction of polycomb targets in vivo. We show that PRCs are required to maintain a compact chromatin state at Hox loci in embryonic stem cells (ESCs). There is specific decompaction in the absence of PRC2 or PRC1. This is due to a PRC1-like complex, since decompaction occurs in Ring1B null cells that still have PRC2-mediated H3K27 methylation. Moreover, we show that the ability of Ring1B to restore a compact chromatin state and to repress Hox gene expression is not dependent on its histone ubiquitination activity. We suggest that Ring1B-mediated chromatin compaction acts to directly limit transcription in vivo.
Collapse
Affiliation(s)
- Ragnhild Eskeland
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Crewe Road, Edinburgh EH4 2XU, UK
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
17
|
Bizari L, Tajara EH, Silva AE. Peripheral position of CCND1 and HER-2/neu oncogenes within chromosome territories in esophageal and gastric cancers non-related to amplification and overexpression. Genet Mol Biol 2009; 32:242-50. [PMID: 21637674 PMCID: PMC3036938 DOI: 10.1590/s1415-47572009005000034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2008] [Accepted: 11/10/2008] [Indexed: 12/02/2022] Open
Abstract
Interphase chromosomes have been shown to occupy discrete regions of the nucleus denominated chromosome territories (CTs), their active genes being preferentially positioned on the surfaces of these CTs, where they are accessible to transcriptional machinery. By means of FISH (Fluorescence in situ Hybridization), we analyzed the CCND1 and HER-2/neu gene positions within the CTs and their relationship with gene amplification and protein over-expression in esophageal and gastric cancers. The CCND1 and HER-2/Neu genes were more often positioned at the periphery (mean frequency of 60%-83%) of the CTs in tumor tissues of the esophagus and stomach. Moreover, this positioning revealed no association with either gene amplification or the protein over-expression status of these genes, although, in esophageal carcinoma, Kappa statistics showed a moderate agreement between amplification of the CCND1 gene (Kappa = 0.400) and its location within the CT, as well as with over-expression of the corresponding protein (Kappa = 0.444). Thus, our results suggest that gene positioning in interphase chromosomes does not follow a definitive pattern neither does it depend only on gene transcriptional activity. Apparently, this positioning could be both gene- and tissue-specific, and depends on other factors acting together, such as dense-gene, chromosome size, chromatin structure, and the level and stability of its expression.
Collapse
Affiliation(s)
- Lucimari Bizari
- Universidade Estadual Paulista Júlio de Mesquita Filho, Brazil
| | | | | |
Collapse
|
18
|
Dekker J. Mapping in vivo chromatin interactions in yeast suggests an extended chromatin fiber with regional variation in compaction. J Biol Chem 2008; 283:34532-40. [PMID: 18930918 PMCID: PMC2596406 DOI: 10.1074/jbc.m806479200] [Citation(s) in RCA: 128] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2008] [Revised: 09/29/2008] [Indexed: 11/06/2022] Open
Abstract
The higher order arrangement of nucleosomes and the level of compaction of the chromatin fiber play important roles in the control of gene expression and other genomic activities. Analysis of chromatin in vitro has suggested that under near physiological conditions chromatin fibers can become highly compact and that the level of compaction can be modulated by histone modifications. However, less is known about the organization of chromatin fibers in living cells. Here, we combine chromosome conformation capture (3C) data with distance measurements and polymer modeling to determine the in vivo mass density of a transcriptionally active 95-kb GC-rich domain on chromosome III of the yeast Saccharomyces cerevisiae. In contrast to previous reports, we find that yeast does not form a compact fiber but that chromatin is extended with a mass per unit length that is consistent with a rather loose arrangement of nucleosomes. Analysis of 3C data from a neighboring AT-rich chromosomal domain indicates that chromatin in this domain is more compact, but that mass density is still well below that of a canonical 30 nm fiber. Our approach should be widely applicable to scale 3C data to real spatial dimensions, which will facilitate the quantification of the effects of chromatin modifications and transcription on chromatin fiber organization.
Collapse
Affiliation(s)
- Job Dekker
- Program in Gene Function and Expression and Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts 01605-0103, USA.
| |
Collapse
|
19
|
Morey C, Da Silva NR, Kmita M, Duboule D, Bickmore WA. Ectopic nuclear reorganisation driven by a Hoxb1 transgene transposed into Hoxd. J Cell Sci 2008; 121:571-7. [PMID: 18252796 DOI: 10.1242/jcs.023234] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The extent to which the nuclear organisation of a gene impacts on its ability to be expressed, or whether nuclear organisation merely reflects gene expression states, remains an important but unresolved issue. A model system that has been instrumental in investigating this question utilises the murine Hox gene clusters encoding homeobox-containing proteins. Nuclear reorganisation and chromatin decondensation, initiated towards the 3' end of the clusters, accompanies activation of Hox genes in both differentiation and development, and might be linked to mechanisms underlying colinearity. To investigate this, and to delineate the cis-acting elements involved, here we analyse the nuclear behaviour of a 3' Hoxb1 transgene transposed to the 5' end of the Hoxd cluster. We show that this transgene contains the cis-acting elements sufficient to initiate ectopic local nuclear reorganisation and chromatin decondensation and to break Hoxd colinearity in the primitive streak region of the early embryo. Significantly, in rhombomere 4, the transgene is able to induce attenuated nuclear reorganisation and decondensation of Hoxd even though there is no detectable expression of the transgene at this site. This shows that reorganisation of chromosome territories and chromatin decondensation can be uncoupled from transcription itself and suggests that they can therefore operate upstream of gene expression.
Collapse
Affiliation(s)
- Céline Morey
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, Edinburgh University, Crewe Road, Edinburgh EH4 2XU, UK
| | | | | | | | | |
Collapse
|
20
|
Chapter 2 Polycomb Group Proteins and Long‐Range Gene Regulation. LONG-RANGE CONTROL OF GENE EXPRESSION 2008; 61:45-66. [DOI: 10.1016/s0065-2660(07)00002-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
|
21
|
Matarazzo MR, Boyle S, D'Esposito M, Bickmore WA. Chromosome territory reorganization in a human disease with altered DNA methylation. Proc Natl Acad Sci U S A 2007; 104:16546-51. [PMID: 17923676 PMCID: PMC2034264 DOI: 10.1073/pnas.0702924104] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2007] [Indexed: 02/07/2023] Open
Abstract
Chromosome territory (CT) organization and chromatin condensation have been linked to gene expression. Although individual genes can be transcribed from inside CTs, some regions that have constitutively high expression or are coordinately activated loop out from CTs and decondense. The relationship between epigenetic marks, such as DNA methylation, and higher-order chromatin structures is largely unexplored. DNMT3B mutations in immunodeficiency centromeric instability facial anomalies (ICF) syndrome result in loss of DNA methylation at particular sites, including CpG islands on the inactive X chromosome (Xi). This allows the specific effects of DNA methylation on CTs to be examined. Using fluorescence in situ hybridization, we reveal a differential organization of the human pseudoautosomal region (PAR)2 between the CTs of the X and Y in normal males and the active X (Xa) and the Xi in females. There is also a more condensed chromatin structure on Xi compared with Xa in this region. PAR2 genes are relocalized toward the outside of the Y and Xi CTs in ICF, and on the Xi, we show that this can extend to genes distant from the site of DNA hypomethylation itself. This reorganization is not simply a reflection of the transcriptional activation of the relocalized genes. This report of altered CT organization in a human genetic disease illustrates that DNA hypomethylation at restricted sites in the genome can lead to more extensive changes in nuclear organization away from the original site of epigenetic change.
Collapse
Affiliation(s)
- Maria R. Matarazzo
- *Institute of Genetics and Biophysics “Adriano Buzzati Traverso,” Consiglio Nazionale delle Ricerche, Via P. Castellino 111, 80131 Naples, Italy; and
| | - Shelagh Boyle
- Medical Research Council Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Crewe Road, Edinburgh EH4 2XU, United Kingdom
| | - Maurizio D'Esposito
- *Institute of Genetics and Biophysics “Adriano Buzzati Traverso,” Consiglio Nazionale delle Ricerche, Via P. Castellino 111, 80131 Naples, Italy; and
| | - Wendy A. Bickmore
- Medical Research Council Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Crewe Road, Edinburgh EH4 2XU, United Kingdom
| |
Collapse
|
22
|
Goetze S, Mateos-Langerak J, Gierman HJ, de Leeuw W, Giromus O, Indemans MHG, Koster J, Ondrej V, Versteeg R, van Driel R. The three-dimensional structure of human interphase chromosomes is related to the transcriptome map. Mol Cell Biol 2007; 27:4475-87. [PMID: 17420274 PMCID: PMC1900058 DOI: 10.1128/mcb.00208-07] [Citation(s) in RCA: 123] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The three-dimensional (3D) organization of the chromosomal fiber in the human interphase nucleus is an important but poorly understood aspect of gene regulation. Here we quantitatively analyze and compare the 3D structures of two types of genomic domains as defined by the human transcriptome map. While ridges are gene dense and show high expression levels, antiridges, on the other hand, are gene poor and carry genes that are expressed at low levels. We show that ridges are in general less condensed, more irregularly shaped, and located more closely to the nuclear center than antiridges. Six human cell lines that display different gene expression patterns and karyotypes share these structural parameters of chromatin. This shows that the chromatin structures of these two types of genomic domains are largely independent of tissue-specific variations in gene expression and differentiation state. Moreover, we show that there is remarkably little intermingling of chromatin from different parts of the same chromosome in a chromosome territory, neither from adjacent nor from distant parts. This suggests that the chromosomal fiber has a compact structure that sterically suppresses intermingling. Together, our results reveal novel general aspects of 3D chromosome architecture that are related to genome structure and function.
Collapse
Affiliation(s)
- Sandra Goetze
- Swammerdam Institute for Life Sciences, University of Amsterdam, Kruislaan 318, Amsterdam, The Netherlands
| | | | | | | | | | | | | | | | | | | |
Collapse
|
23
|
Dekker J. GC- and AT-rich chromatin domains differ in conformation and histone modification status and are differentially modulated by Rpd3p. Genome Biol 2007; 8:R116. [PMID: 17577398 PMCID: PMC2394764 DOI: 10.1186/gb-2007-8-6-r116] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2007] [Accepted: 06/18/2007] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Base-composition varies throughout the genome and is related to organization of chromosomes in distinct domains (isochores). Isochore domains differ in gene expression levels, replication timing, levels of meiotic recombination and chromatin structure. The molecular basis for these differences is poorly understood. RESULTS We have compared GC- and AT-rich isochores of yeast with respect to chromatin conformation, histone modification status and transcription. Using 3C analysis we show that, along chromosome III, GC-rich isochores have a chromatin structure that is characterized by lower chromatin interaction frequencies compared to AT-rich isochores, which may point to a more extended chromatin conformation. In addition, we find that throughout the genome, GC-rich and AT-rich genes display distinct levels of histone modifications. Interestingly, elimination of the histone deacetylase Rpd3p differentially affects conformation of GC- and AT-rich domains. Further, deletion of RPD3 activates expression of GC-rich genes more strongly than AT-rich genes. Analyses of effects of the histone deacetylase inhibitor trichostatin A, global patterns of Rpd3p binding and effects of deletion of RPD3 on histone H4 acetylation confirmed that conformation and activity of GC-rich chromatin are more sensitive to Rpd3p-mediated deacetylation than AT-rich chromatin. CONCLUSION We find that GC-rich and AT-rich chromatin domains display distinct chromatin conformations and are marked by distinct patterns of histone modifications. We identified the histone deacetylase Rpd3p as an attenuator of these base composition-dependent differences in chromatin status. We propose that GC-rich chromatin domains tend to occur in a more active conformation and that Rpd3p activity represses this propensity throughout the genome.
Collapse
Affiliation(s)
- Job Dekker
- Program in Gene Function and Expression and Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Plantation Street, Worcester, MA 01605-4321, USA.
| |
Collapse
|
24
|
Cohen SM, Furey TS, Doggett NA, Kaufman DG. Genome-wide sequence and functional analysis of early replicating DNA in normal human fibroblasts. BMC Genomics 2006; 7:301. [PMID: 17134498 PMCID: PMC1702361 DOI: 10.1186/1471-2164-7-301] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2006] [Accepted: 11/29/2006] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND The replication of mammalian genomic DNA during the S phase is a highly coordinated process that occurs in a programmed manner. Recent studies have begun to elucidate the pattern of replication timing on a genomic scale. Using a combination of experimental and computational techniques, we identified a genome-wide set of the earliest replicating sequences. This was accomplished by first creating a cosmid library containing DNA enriched in sequences that replicate early in the S phase of normal human fibroblasts. Clone ends were then sequenced and aligned to the human genome. RESULTS By clustering adjacent or overlapping early replicating clones, we identified 1759 "islands" averaging 100 kb in length, allowing us to perform the most detailed analysis to date of DNA characteristics and genes contained within early replicating DNA. Islands are enriched in open chromatin, transcription related elements, and Alu repetitive elements, with an underrepresentation of LINE elements. In addition, we found a paucity of LTR retroposons, DNA transposon sequences, and an enrichment in all classes of tandem repeats, except for dinucleotides. CONCLUSION An analysis of genes associated with islands revealed that nearly half of all genes in the WNT family, and a number of genes in the base excision repair pathway, including four of ten DNA glycosylases, were associated with island sequences. Also, we found an overrepresentation of members of apoptosis-associated genes in very early replicating sequences from both fibroblast and lymphoblastoid cells. These data suggest that there is a temporal pattern of replication for some functionally related genes.
Collapse
Affiliation(s)
- Stephanie M Cohen
- Department of Pathology and Laboratory Medicine, University of North Carolina, Chapel Hill, North Carolina 27599, USA
| | - Terrence S Furey
- Institute for Genome Sciences and Policy, Duke University, Durham, NC, 27708, USA
| | - Norman A Doggett
- Bioscience Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - David G Kaufman
- Department of Pathology and Laboratory Medicine, University of North Carolina, Chapel Hill, North Carolina 27599, USA
| |
Collapse
|
25
|
Würtele H, Chartrand P. Genome-wide scanning of HoxB1-associated loci in mouse ES cells using an open-ended Chromosome Conformation Capture methodology. Chromosome Res 2006; 14:477-95. [PMID: 16823611 DOI: 10.1007/s10577-006-1075-0] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2006] [Accepted: 05/05/2006] [Indexed: 12/18/2022]
Abstract
Spatial proximity between genomic loci can play important roles in their function and regulation. We have developed an open-ended method based on Chromosome Conformation Capture technology allowing us to perform genome-wide scanning of the loci that form the spatial environment of a given locus at a given time. As a proof of principle we present the use of this methodology to investigate the dynamics of the spatial environment of the HoxB1 gene before and after the induction of its expression in mouse embryonic stem cells. Our results indicate that the HoxB1 locus' immediate spatial environment can be divided roughly into three parts: a first part is represented by a domain of immediate proximity on each side of the HoxB1 locus covering approximately 110 kb, a second part extends to a domain of 800 kb and a third part consists of distal intra-chromosomal and inter-chromosomal interactions. Consistent with FISH studies showing the decondensation and repositioning of HoxB1 outside of its chromosomal territory during its expression, the proportion of inter-chromosomal interactions between HoxB1 and the rest of the genome increases after its induction, while interactions with distal intra-chromosomal loci become less frequent. These results indicate that this technique can be used to determine the dynamics of loci interactions on a genome-wide scale.
Collapse
Affiliation(s)
- Hugo Würtele
- Molecular Biology Program, Université de Montreal, CP 6128, succ. Centre-ville, Montréal, Québec, H3C 3J7, Canada
| | | |
Collapse
|
26
|
Codina-Pascual M, Campillo M, Kraus J, Speicher MR, Egozcue J, Navarro J, Benet J. Crossover frequency and synaptonemal complex length: their variability and effects on human male meiosis. Mol Hum Reprod 2006; 12:123-33. [PMID: 16449239 DOI: 10.1093/molehr/gal007] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
In this study, immunocytogenetics has been used in combination with the subtelomere-specific multiplex-fluorescent in-situ hybridization (stM-FISH) assay to identify 4681 autosomal synaptonemal complexes (SCs) of two fertile men. Comparisons of crossover maps for each individual SC between two men with extremely different meiotic crossover frequencies show that a low crossover frequency results in (i) a higher frequency of XY pairs and of small SCs without MLH1 foci and (ii) lower frequency of crossovers in the proximity of centromeres. In both cases, the bivalents which most frequently lacked MLH1 foci were the XY pair and the SC21. Analysis of SC length showed that SC arms can be longer or shorter than the corresponding mitotic one. Moreover, for a given SC, the variation in length found in one arm was independent of the variation observed in the other one (e.g. SC1p arms are longer than SC1q arms). The results confirmed that reduction in the crossover frequency may increase the risk of achiasmate small bivalents and that interindividual differences in crossover frequency could explain the variability in the frequencies of aneuploidy in human sperm. How MLH1 foci are positioned within the SC is discussed based on detailed MLH1 foci distributions and interfoci distances. Finally, evidence that the variation of the SC arm length may reflect the abundance of open and of compact chromatin fibers in the arm is shown.
Collapse
Affiliation(s)
- M Codina-Pascual
- Unitat de Biologia Cellular i Genètica Mèdica, Departament de Biologia Cellular, Fisiologia i Immunologia, Universitat Autònoma de Barcelona, Bellaterra 08193, Spain
| | | | | | | | | | | | | |
Collapse
|
27
|
Murmann AE, Gao J, Encinosa M, Gautier M, Peter ME, Eils R, Lichter P, Rowley JD. Local gene density predicts the spatial position of genetic loci in the interphase nucleus. Exp Cell Res 2005; 311:14-26. [PMID: 16202404 DOI: 10.1016/j.yexcr.2005.07.020] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2005] [Revised: 07/19/2005] [Accepted: 07/20/2005] [Indexed: 12/12/2022]
Abstract
Specific chromosomal translocations are hallmarks of many human leukemias. The basis for these translocation events is poorly understood, but it has been assumed that spatial positioning of genes in the nucleus of hematopoietic cells is a contributing factor. Analysis of the nuclear 3D position of the gene MLL, frequently involved in chromosomal translocations and five of its translocation partners (AF4, AF6, AF9, ENL and ELL), and two control loci revealed a characteristic radial distribution pattern in all hematopoietic cells studied. Genes in areas of high local gene density were found positioned towards the nuclear center, whereas genes in regions of low gene density were detected closer to the nuclear periphery. The gene density within a 2 Mbp window was found to be a better predictor for the relative positioning of a genomic locus within the cell nucleus than the gene density of entire chromosomes. Analysis of the position of MLL, AF4, AF6 and AF9 in cell lines carrying chromosomal translocations involving these genes revealed that the position of the normal genes was different from that of the fusion genes, and this was again consistent with the changes in local gene density within a 2 Mbp window. Thus, alterations in gene density directly at translocation junctions could explain the change in the position of affected genes in leukemia cells.
Collapse
Affiliation(s)
- Andrea E Murmann
- Department of Medicine, Section Hematology/Oncology, University of Chicago, Chicago, IL 60637, USA
| | | | | | | | | | | | | | | |
Collapse
|
28
|
McNamara G, Difilippantonio MJ, Ried T. Microscopy and image analysis. CURRENT PROTOCOLS IN HUMAN GENETICS 2005; Chapter 4:Unit 4.4. [PMID: 18428379 PMCID: PMC4772429 DOI: 10.1002/0471142905.hg0404s46] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
This unit provides an overview of light microscopy, including objectives, light sources, filters, film, and color photography for fluorescence microscopy and fluorescence in situ hybridization (FISH). Computerized image-analysis systems currently used in clinical cytogenetics are also discussed.
Collapse
Affiliation(s)
- George McNamara
- Childrens Hospital Los Angeles, Los Angeles, California, USA
| | | | | |
Collapse
|
29
|
Gilbert N, Boyle S, Fiegler H, Woodfine K, Carter NP, Bickmore WA. Chromatin architecture of the human genome: gene-rich domains are enriched in open chromatin fibers. Cell 2004; 118:555-66. [PMID: 15339661 DOI: 10.1016/j.cell.2004.08.011] [Citation(s) in RCA: 360] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2004] [Revised: 07/08/2004] [Accepted: 07/13/2004] [Indexed: 10/26/2022]
Abstract
We present an analysis of chromatin fiber structure across the human genome. Compact and open chromatin fiber structures were separated by sucrose sedimentation and their distributions analyzed by hybridization to metaphase chromosomes and genomic microarrays. We show that compact chromatin fibers originate from some sites of heterochromatin (C-bands), and G-bands (euchromatin). Open chromatin fibers correlate with regions of highest gene density, but not with gene expression since inactive genes can be in domains of open chromatin, and active genes in regions of low gene density can be embedded in compact chromatin fibers. Moreover, we show that chromatin fiber structure impacts on further levels of chromatin condensation. Regions of open chromatin fibers are cytologically decondensed and have a distinctive nuclear organization. We suggest that domains of open chromatin may create an environment that facilitates transcriptional activation and could provide an evolutionary constraint to maintain clusters of genes together along chromosomes.
Collapse
Affiliation(s)
- Nick Gilbert
- MRC Human Genetics Unit, Edinburgh, EH4 2XU, Scotland
| | | | | | | | | | | |
Collapse
|
30
|
Chambeyron S, Bickmore WA. Chromatin decondensation and nuclear reorganization of the HoxB locus upon induction of transcription. Genes Dev 2004; 18:1119-30. [PMID: 15155579 PMCID: PMC415637 DOI: 10.1101/gad.292104] [Citation(s) in RCA: 491] [Impact Index Per Article: 24.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The colinearity of genes in Hox clusters suggests a role for chromosome structure in gene regulation. We reveal programmed changes in chromatin structure and nuclear organization upon induction of Hoxb expression by retinoic acid. There is an early increase in the histone modifications that are marks of active chromatin at both the early expressed gene Hoxb1, and also at Hoxb9 that is not expressed until much later. There is also a visible decondensation of the chromatin between Hoxb1 and Hoxb9 at this early stage. However, a further change in higher-order chromatin structure, looping out of genes from the chromosome territory, occurs in synchrony with the execution of the gene expression program. We suggest that higher-order chromatin structure regulates the expression of the HoxB cluster at several levels. Locus-wide changes in chromatin structure (histone modification and chromatin decondensation) may establish a transcriptionally poised state but are not sufficient for the temporal program of gene expression. The choreographed looping out of decondensed chromatin from chromosome territories may then allow for activation of high levels of transcription from the sequence of genes along the cluster.
Collapse
|
31
|
Lukásová E, Kozubek S, Falk M, Kozubek M, Zaloudík J, Vagunda V, Pavlovský Z. Topography of genetic loci in the nuclei of cells of colorectal carcinoma and adjacent tissue of colonic epithelium. Chromosoma 2004; 112:221-30. [PMID: 14722711 DOI: 10.1007/s00412-003-0263-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2002] [Revised: 08/25/2003] [Accepted: 10/02/2003] [Indexed: 01/08/2023]
Abstract
To determine the influence of increased gene expression and amplification in colorectal carcinoma on chromatin structure, the nuclear distances between pairs of bacterial artificial chromosome (BAC) clones with genomic separation from 800 to 29,000 kb were measured and compared between the tumor and parallel epithelial cells of six patients. The nuclear distances were measured between the loci in chromosomal bands 7p22.3-7p21.3; 7q35-7q36.3; 11p15.5-11p15.4; 20p13; 20p12.2; 20q11.21 and 20q12 where increased expression had been found in all types of colorectal carcinoma. The loci were visualized by three-dimensional fluorescence in situ hybridization using 22 BAC clones. Our results show that for short genomic separations, mean nuclear distance increases linearly with increased genomic separation. The results for some pairs of loci fell outside this linear slope, indicating the existence of different levels of chromatin folding. For the same genomic separations the nuclear distances were frequently shorter for tumor as compared with epithelial cells. Above the initial growing phase of the nuclear distances, a plateau phase was observed in both cell types where the increase in genomic separation was not accompanied by an increase in nuclear distance. The ratio of the mean nuclear distances between the corresponding loci in tumor and epithelium cells decreases with increasing amplification of loci. Our results further show that the large-scale chromatin folding might differ for specific regions of chromosomes and that it is basically preserved in tumor cells in spite of the amplification of many loci.
Collapse
Affiliation(s)
- Emilie Lukásová
- Institute of Biophysics, Czech Academy of Sciences, Královopolská 135, 612 65 Brno, Czech Republic
| | | | | | | | | | | | | |
Collapse
|
32
|
Bickmore WA, Mahy NL, Chambeyron S. Do higher-order chromatin structure and nuclear reorganization play a role in regulating Hox gene expression during development? COLD SPRING HARBOR SYMPOSIA ON QUANTITATIVE BIOLOGY 2004; 69:251-7. [PMID: 16117656 DOI: 10.1101/sqb.2004.69.251] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Affiliation(s)
- W A Bickmore
- MRC Human Genetics Unit, Edinburgh EH4 2XU, Scotland, United Kingdom
| | | | | |
Collapse
|
33
|
Blat Y, Protacio RU, Hunter N, Kleckner N. Physical and functional interactions among basic chromosome organizational features govern early steps of meiotic chiasma formation. Cell 2002; 111:791-802. [PMID: 12526806 DOI: 10.1016/s0092-8674(02)01167-4] [Citation(s) in RCA: 265] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Analysis of meiotic recombination by functional genomic approaches reveals prominent spatial and functional interactions among diverse organizational determinants. Recombination occurs between chromatin loop sequences; however, these sequences are spatially tethered to underlying chromosome axes via their recombinosomes. Meiotic chromosomal protein, Red1, localizes to chromosome axes; however, Red1 loading is modulated by R/G-bands isochores and thus by bulk chromatin state. Recombination is also modulated by isochore determinants: R-bands differentially favor double-strand break (DSB) formation but disfavor subsequent loading of meiotic RecA homolog, Dmc1. Red1 promotes DSB formation in both R- and G-bands and then promotes Dmc1 loading, specifically counteracting disfavoring R-band effects. These complexities are discussed in the context of chiasma formation as a series of coordinated local changes at the DNA and chromosome-axis levels.
Collapse
Affiliation(s)
- Yuval Blat
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA
| | | | | | | |
Collapse
|
34
|
Saccone S, Federico C, Bernardi G. Localization of the gene-richest and the gene-poorest isochores in the interphase nuclei of mammals and birds. Gene 2002; 300:169-78. [PMID: 12468098 DOI: 10.1016/s0378-1119(02)01038-7] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
At a resolution of 850 bands, human chromosomes comprise two subsets of bands, the GC-richest H3(+) and the GC-poorest L1(+) bands, accounting for about 17 and 26%, respectively, of all bands. The former are a subset of the R bands and the latter are a subset of the G bands. These bands showed the highest and the lowest gene densities, respectively, as well as a number of other distinct features. Here we report that human and chicken interphase nuclei are characterized by the following features. (1) The gene-richest/GC-richest chromosomal regions are predominantly distributed in internal locations, whereas the gene-poorest/GC-poorest DNA regions are close to the nuclear envelope. (2) The interphase chromosomes seem to be characterized by a polar arrangement, because the gene-richest/GC-richest bands and the gene-poorest/GC-poorest bands are predominantly located in the distal and proximal regions, respectively, of chromosomes, and because interphase chromosomes are extremely long. While this polar arrangement is evident in the larger chromosomes, it is not displayed by the chicken microchromosomes and by some small human chromosomes, namely by chromosomes that are almost only composed by GC-rich or by GC-poor DNA. (3) The gene-richest chromosomal regions display a much more spread-out conformation compared to the gene-poorest regions in human nuclei. This finding has interesting implications for the formation of GC-rich isochores of warm-blooded vertebrates.
Collapse
Affiliation(s)
- Salvatore Saccone
- Dipartimento di Biologia Animale, University of Catania, via Androne 81, 95124, Catania, Italy
| | | | | |
Collapse
|
35
|
Saccone S, Pavlicek A, Federico C, Paces J, Bernard G. Genes, isochores and bands in human chromosomes 21 and 22. Chromosome Res 2002; 9:533-9. [PMID: 11721952 DOI: 10.1023/a:1012443217627] [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] [Indexed: 11/12/2022]
Abstract
The recently available DNA sequences from chromosomes 21 and 22 enabled us to define the relationships of different band types with isochores and with gene concentration and to compare these relationships with previous results. We showed that chromosomal bands appear as Giemsa or Reverse bands depending not on their absolute GC level, but on the composition GC level relative to those of adjacent contiguous bands. We also demonstrated that the GC-richest, and gene-richest H3+ bands are characterized by a lower DNA compaction compared with the GC-poorest, gene-poorest L1+ bands. Moreover, our results indicate that the human genome contains about 30,000 genes.
Collapse
Affiliation(s)
- S Saccone
- Dipartimento di Protezione e Valorizzazione Agroalimentare, University of Bologna, Reggio Emilia, Italy
| | | | | | | | | |
Collapse
|
36
|
Ostashevsky J. A polymer model for large-scale chromatin organization in lower eukaryotes. Mol Biol Cell 2002; 13:2157-69. [PMID: 12058077 PMCID: PMC117632 DOI: 10.1091/mbc.02-01-0608] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2002] [Revised: 02/28/2002] [Accepted: 03/08/2002] [Indexed: 11/11/2022] Open
Abstract
A quantitative model of large-scale chromatin organization was applied to nuclei of fission yeast Schizosaccharomyces pombe (meiotic prophase and G2 phase), budding yeast Saccharomyces cerevisiae (young and senescent cells), Drosophila (embryonic cycles 10 and 14, and polytene tissues) and Caenorhabditis elegans (G1 phase). The model is based on the coil-like behavior of chromosomal fibers and the tight packing of discrete chromatin domains in a nucleus. Intrachromosomal domains are formed by chromatin anchoring to nuclear structures (e.g., the nuclear envelope). The observed sizes for confinement of chromatin diffusional motion are similar to the estimated sizes of corresponding domains. The model correctly predicts chromosome configurations (linear, Rabl, loop) and chromosome associations (homologous pairing, centromere and telomere clusters) on the basis of the geometrical constraints imposed by nuclear size and shape. Agreement between the model predictions and literature observations supports the notion that the average linear density of the 30-nm chromatin fiber is approximately 4 nucleosomes per 10 nm contour length.
Collapse
Affiliation(s)
- Joseph Ostashevsky
- Department of Radiation Oncology, SUNY Downstate Medical Center, Brooklyn, New York 11203, USA.
| |
Collapse
|
37
|
Mahy NL, Perry PE, Gilchrist S, Baldock RA, Bickmore WA. Spatial organization of active and inactive genes and noncoding DNA within chromosome territories. J Cell Biol 2002; 157:579-89. [PMID: 11994314 PMCID: PMC2173868 DOI: 10.1083/jcb.200111071] [Citation(s) in RCA: 183] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The position of genes within the nucleus has been correlated with their transcriptional activity. The interchromosome domain model of nuclear organization suggests that genes preferentially locate at the surface of chromosome territories. Conversely, high resolution analysis of chromatin fibers suggests that chromosome territories do not present accessibility barriers to transcription machinery. To clarify the relationship between the organization of chromosome territories and gene expression, we have used fluorescence in situ hybridization to analyze the spatial organization of a contiguous approximately 1 Mb stretch of the Wilms' tumor, aniridia, genitourinary anomalies, mental retardation syndrome region of the human genome and the syntenic region in the mouse. These regions contain constitutively expressed genes, genes with tissue-restricted patterns of expression, and substantial regions of intergenic DNA. We find that there is a spatial organization within territories that is conserved between mouse and humans: certain sequences do preferentially locate at the periphery of the chromosome territories in both species. However, we do not detect genes necessarily at the periphery of chromosome territories or at the surface of subchromosomal domains. Intraterritory organization is not different among cell types that express different combinations of the genes under study. Our data demonstrate that transcription of both ubiquitous and tissue-restricted genes is not confined to the periphery of chromosome territories, suggesting that the basal transcription machinery and transcription factors can readily gain access to the chromosome interior.
Collapse
Affiliation(s)
- Nicola L Mahy
- Medical Research Council Human Genetics Unit, Edinburgh EH4 2XU, United Kingdom
| | | | | | | | | |
Collapse
|
38
|
Niimura Y, Gojobori T. In silico chromosome staining: reconstruction of Giemsa bands from the whole human genome sequence. Proc Natl Acad Sci U S A 2002; 99:797-802. [PMID: 11792839 PMCID: PMC117385 DOI: 10.1073/pnas.022437999] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2001] [Indexed: 11/18/2022] Open
Abstract
Giemsa staining has been used for identifying individual human chromosomes. Giemsa-dark and -light bands generally are thought to correspond to GC-poor and GC-rich regions; however, several experiments showed that the correspondence is quite poor. To elucidate the precise relationship between GC content and Giemsa banding patterns, we developed an "in silico chromosome staining" method for reconstructing Giemsa bands computationally from the whole human genome sequence. Here we show that 850-level Giemsa bands are best correlated with the difference in GC content between a local window of 2.5 megabases and a regional window of 9.3 megabases along a chromosome. The correlations are of strong statistical significance for almost all 43 chromosomal arms. Our results clearly show that Giemsa-dark bands are locally GC-poor regions compared with the flanking regions. These findings are consistent with the model that matrix-associated regions, which are known to be AT-rich, are present more densely in Giemsa-dark bands than in -light bands.
Collapse
Affiliation(s)
- Yoshihito Niimura
- Center for Information Biology and DNA Data Bank of Japan, National Institute of Genetics, 1111, Yata, Mishima, Shizuoka 411-8540, Japan
| | | |
Collapse
|
39
|
Williams RRE, Broad S, Sheer D, Ragoussis J. Subchromosomal positioning of the epidermal differentiation complex (EDC) in keratinocyte and lymphoblast interphase nuclei. Exp Cell Res 2002; 272:163-75. [PMID: 11777341 DOI: 10.1006/excr.2001.5400] [Citation(s) in RCA: 161] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The epidermal differentiation complex (EDC) at 1q21 is host to many structurally and functionally related genes coding for proteins involved in the differentiation process of keratinocytes. The grouping together of these genes which share spatial and temporal expression and interrelated functions is a remarkable genomic feature which has led to suggestions that the region may have a coordinated transcription control mechanism. With the growing awareness that the organization of the genome within the interphase nucleus is relevant to transcriptional activity, we have investigated the spatial organization of the EDC in the nuclei of keratinocytes, where the EDC genes are highly expressed, and lymphoblasts, where they are silent. Using 2D and 3D FISH we find that in keratinocyte nuclei the EDC is frequently positioned external to the chromosome 1 territory compared to lymphoblasts where the EDC more often adopts a peripheral or internal location. It has been previously shown that the MHC region can extend from the chromosome 6 territory in relation to transcriptional activity. This study of the EDC thus provides a further example of a gene-dense complex capable of assuming extraterritorial positioning in relation to cell type/transcription status.
Collapse
Affiliation(s)
- Ruth R E Williams
- Genomics Laboratory, King's College London, London, SE1 9RT, England, UK.
| | | | | | | |
Collapse
|
40
|
Carvalho C, Pereira HM, Ferreira J, Pina C, Mendonça D, Rosa AC, Carmo-Fonseca M. Chromosomal G-dark bands determine the spatial organization of centromeric heterochromatin in the nucleus. Mol Biol Cell 2001; 12:3563-72. [PMID: 11694589 PMCID: PMC60276 DOI: 10.1091/mbc.12.11.3563] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Gene expression can be silenced by proximity to heterochromatin blocks containing centromeric alpha-satellite DNA. This has been shown experimentally through cis-acting chromosome rearrangements resulting in linear genomic proximity, or through trans-acting changes resulting in intranuclear spatial proximity. Although it has long been been established that centromeres are nonrandomly distributed during interphase, little is known of what determines the three-dimensional organization of these silencing domains in the nucleus. Here, we propose a model that predicts the intranuclear positioning of centromeric heterochromatin for each individual chromosome. With the use of fluorescence in situ hybridization and confocal microscopy, we show that the distribution of centromeric alpha-satellite DNA in human lymphoid cells synchronized at G(0)/G(1) is unique for most individual chromosomes. Regression analysis reveals a tight correlation between nuclear distribution of centromeric alpha-satellite DNA and the presence of G-dark bands in the corresponding chromosome. Centromeres surrounded by G-dark bands are preferentially located at the nuclear periphery, whereas centromeres of chromosomes with a lower content of G-dark bands tend to be localized at the nucleolus. Consistent with the model, a t(11; 14) translocation that removes G-dark bands from chromosome 11 causes a repositioning of the centromere, which becomes less frequently localized at the nuclear periphery and more frequently associated with the nucleolus. The data suggest that "chromosomal environment" plays a key role in the intranuclear organization of centromeric heterochromatin. Our model further predicts that facultative heterochromatinization of distinct genomic regions may contribute to cell-type specific patterns of centromere localization.
Collapse
Affiliation(s)
- C Carvalho
- Instituto de Histologia e Embriologia, Faculdade de Medicina, Universidade de Lisboa, 1649-028 Lisboa, Portugal
| | | | | | | | | | | | | |
Collapse
|
41
|
Abstract
By using a fluorescence in situ hybridization technique we revealed that for nine different q-arm telomere markers the positioning of chromosomes in human G(1) interphase nuclei was chromosome size-dependent. The q-arm telomeres of large chromosomes are more peripherally located than telomeres on small chromosomes. This highly organized arrangement of chromatin within the human nucleus was discovered by determining the x and y coordinates of the hybridization sites and calculating the root-mean-square radial distance to the nuclear centers in human fibroblasts. We demonstrate here that global organization within the G(1) interphase nucleus is affected by one of the most fundamental physical quantities-chromosome size or mass-and propose two biophysical models, a volume exclusion model and a mitotic preset model, to explain our finding.
Collapse
Affiliation(s)
- H B Sun
- Biomedical Engineering Program, Indiana University Purdue University at Indianapolis, Indianapolis, Indiana 46202, USA
| | | | | |
Collapse
|
42
|
Volpi EV, Chevret E, Jones T, Vatcheva R, Williamson J, Beck S, Campbell RD, Goldsworthy M, Powis SH, Ragoussis J, Trowsdale J, Sheer D. Large-scale chromatin organization of the major histocompatibility complex and other regions of human chromosome 6 and its response to interferon in interphase nuclei. J Cell Sci 2000; 113 ( Pt 9):1565-76. [PMID: 10751148 DOI: 10.1242/jcs.113.9.1565] [Citation(s) in RCA: 315] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The large-scale chromatin organization of the major histocompatibility complex and other regions of chromosome 6 was studied by three-dimensional image analysis in human cell types with major differences in transcriptional activity. Entire gene clusters were visualized by fluorescence in situ hybridization with multiple locus-specific probes. Individual genomic regions showed distinct configurations in relation to the chromosome 6 terrritory. Large chromatin loops containing several megabases of DNA were observed extending outwards from the surface of the domain defined by the specific chromosome 6 paint. The frequency with which a genomic region was observed on an external chromatin loop was cell type dependent and appeared to be related to the number of active genes in that region. Transcriptional up-regulation of genes in the major histocompatibility complex by interferon-gamma led to an increase in the frequency with which this large gene cluster was found on an external chromatin loop. Our data are consistent with an association between large-scale chromatin organization of specific genomic regions and their transcriptional status.
Collapse
Affiliation(s)
- E V Volpi
- Human Cytogenetics Laboratory, Imperial Cancer Research Fund, London WC2A 3PX, UK
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
43
|
Sun HB, Yokota H. Correlated positioning of homologous chromosomes in daughter fibroblast cells. Chromosome Res 2000; 7:603-10. [PMID: 10628661 DOI: 10.1023/a:1009279918034] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
A new method of analyzing chromosome segregation in pairs of daughter human fibroblasts revealed that the positioning of chromosomes in daughter nuclei was closely correlated with their relative positions during the G1 interphase. Two topographic values, namely distance and the angular separation between a pair of homologous chromosomes, were determined using fluorescence in-situ hybridization with four different centromeric DNA probes. These topographical values exhibited a broad distribution as a population, but, to our surprise, both were strongly correlated within each pair of cells derived from the same mother cell (daughters). This correlation was not affected by cell-to-cell distances between daughter cells. We demonstrate in this report that the positioning of chromosomes at G1 interphase is chiefly determined by their configuration at mitosis, consistent with the nuclear architecture model in which chromosomes are immobile at a global scale in the G1 interphase nuclei.
Collapse
Affiliation(s)
- H B Sun
- Department of Mechanical Engineering, Indiana University Purdue University at Indianapolis, 46202, USA
| | | |
Collapse
|
44
|
Tumbar T, Sudlow G, Belmont AS. Large-scale chromatin unfolding and remodeling induced by VP16 acidic activation domain. J Cell Biol 1999; 145:1341-54. [PMID: 10385516 PMCID: PMC2133171 DOI: 10.1083/jcb.145.7.1341] [Citation(s) in RCA: 261] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Analysis of the relationship between transcriptional activators and chromatin organization has focused largely on lower levels of chromatin structure. Here we describe striking remodeling of large-scale chromatin structure induced by a strong transcriptional activator. A VP16-lac repressor fusion protein targeted the VP16 acidic activation domain to chromosome regions containing lac operator repeats. Targeting was accompanied by increased transcription, localized histone hyperacetylation, and recruitment of at least three different histone acetyltransferases. Observed effects on large-scale chromatin structure included unfolding of a 90-Mbp heterochromatic chromosome arm into an extended 25-40-micrometers chromonema fiber, remodeling of this fiber into a novel subnuclear domain, and propagation of large-scale chromatin unfolding over hundreds of kilobase pairs. These changes in large-scale chromatin structure occurred even with inhibition of ongoing transcription by alpha-amanitin. Our results suggest a functional link between recruitment of the transcriptional machinery and changes in large-scale chromatin structure. Based on the observed long-range propagation of changes in large-scale chromatin structure, we suggest a possible rationale for the observed clustering of housekeeping genes within Mbp-sized chromosome bands.
Collapse
Affiliation(s)
- T Tumbar
- Program in Biophysics and Computational Biology, University of Illinois, Urbana-Champaign, Urbana, Illinois 61801, USA
| | | | | |
Collapse
|
45
|
Croft JA, Bridger JM, Boyle S, Perry P, Teague P, Bickmore WA. Differences in the localization and morphology of chromosomes in the human nucleus. J Biophys Biochem Cytol 1999; 145:1119-31. [PMID: 10366586 PMCID: PMC2133153 DOI: 10.1083/jcb.145.6.1119] [Citation(s) in RCA: 659] [Impact Index Per Article: 26.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Using fluorescence in situ hybridization we show striking differences in nuclear position, chromosome morphology, and interactions with nuclear substructure for human chromosomes 18 and 19. Human chromosome 19 is shown to adopt a more internal position in the nucleus than chromosome 18 and to be more extensively associated with the nuclear matrix. The more peripheral localization of chromosome 18 is established early in the cell cycle and is maintained thereafter. We show that the preferential localization of chromosomes 18 and 19 in the nucleus is reflected in the orientation of translocation chromosomes in the nucleus. Lastly, we show that the inhibition of transcription can have gross, but reversible, effects on chromosome architecture. Our data demonstrate that the distribution of genomic sequences between chromosomes has implications for nuclear structure and we discuss our findings in relation to a model of the human nucleus that is functionally compartmentalized.
Collapse
MESH Headings
- Cell Cycle/drug effects
- Cell Line
- Cell Nucleus/drug effects
- Cell Nucleus/genetics
- Cell Nucleus/metabolism
- Cells, Cultured
- Centromere/metabolism
- Centromere/ultrastructure
- Chromosomes, Human, Pair 18/chemistry
- Chromosomes, Human, Pair 18/genetics
- Chromosomes, Human, Pair 18/metabolism
- Chromosomes, Human, Pair 18/ultrastructure
- Chromosomes, Human, Pair 19/chemistry
- Chromosomes, Human, Pair 19/genetics
- Chromosomes, Human, Pair 19/metabolism
- Chromosomes, Human, Pair 19/ultrastructure
- DNA/metabolism
- Dactinomycin/pharmacology
- Dichlororibofuranosylbenzimidazole/pharmacology
- Fibroblasts/cytology
- Fibroblasts/drug effects
- Fibroblasts/metabolism
- Histone Deacetylase Inhibitors
- Histone Deacetylases/metabolism
- Humans
- Hydroxamic Acids/pharmacology
- In Situ Hybridization, Fluorescence
- Lymphocytes/cytology
- Lymphocytes/drug effects
- Lymphocytes/metabolism
- Nuclear Matrix/drug effects
- Nuclear Matrix/genetics
- Nuclear Matrix/metabolism
- RNA Polymerase II/antagonists & inhibitors
- RNA Polymerase II/metabolism
- Telomere/metabolism
- Telomere/ultrastructure
- Transcription, Genetic/drug effects
- Translocation, Genetic
Collapse
Affiliation(s)
- J A Croft
- MRC Human Genetics Unit, Western General Hospital, Edinburgh EH4 2XU, United Kingdom
| | | | | | | | | | | |
Collapse
|
46
|
Ostashevsky J. A polymer model for the structural organization of chromatin loops and minibands in interphase chromosomes. Mol Biol Cell 1998; 9:3031-40. [PMID: 9802894 PMCID: PMC25584 DOI: 10.1091/mbc.9.11.3031] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
A quantitative model of interphase chromosome higher-order structure is presented based on the isochore model of the genome and results obtained in the field of copolymer research. G1 chromosomes are approximated in the model as multiblock copolymers of the 30-nm chromatin fiber, which alternately contain two types of 0.5- to 1-Mbp blocks (R and G minibands) differing in GC content and DNA-bound proteins. A G1 chromosome forms a single-chain string of loop clusters (micelles), with each loop approximately 1-2 Mbp in size. The number of approximately 20 loops per micelle was estimated from the dependence of geometrical versus genomic distances between two points on a G1 chromosome. The greater degree of chromatin extension in R versus G minibands and a difference in the replication time for these minibands (early S phase for R versus late S phase for G) are explained in this model as a result of the location of R minibands at micelle cores and G minibands at loop apices. The estimated number of micelles per nucleus is close to the observed number of replication clusters at the onset of S phase. A relationship between chromosomal and nuclear sizes for several types of higher eukaryotic cells (insects, plants, and mammals) is well described through the micelle structure of interphase chromosomes. For yeast cells, this relationship is described by a linear coil configuration of chromosomes.
Collapse
Affiliation(s)
- J Ostashevsky
- Department of Radiation Oncology, State University of New York, Health Science Center at Brooklyn, Brooklyn, New York 11203, USA.
| |
Collapse
|
47
|
Abstract
The first complete genomic sequence of a eukaryote (Saccharomyces cerevisiae) has already been accomplished. It is estimated that the sequence of the human genome will be known early in the next millennium. Yet it is already apparent that, despite their immense length, these linear primary sequence maps will be inadequate descriptions of the eukaryotic genome, be it of a budding yeast or a human. To reflect our growing awareness of the importance of spatial context in chromosome function and in gene expression we argue that a more complete map of the genome should seek to embody the richness of information that we expect of the maps we use to navigate our way around the outside world.
Collapse
|