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Kumar P, Gholamalamdari O, Zhang Y, Zhang L, Vertii A, van Schaik T, Peric-Hupkes D, Sasaki T, Gilbert DM, van Steensel B, Ma J, Kaufman PD, Belmont AS. Nucleolus and centromere TSA-Seq reveals variable localization of heterochromatin in different cell types. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.29.564613. [PMID: 37961445 PMCID: PMC10634939 DOI: 10.1101/2023.10.29.564613] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
Genome differential positioning within interphase nuclei remains poorly explored. We extended and validated TSA-seq to map genomic regions near nucleoli and pericentric heterochromatin in four human cell lines. Our study confirmed that smaller chromosomes localize closer to nucleoli but further deconvolved this by revealing a preference for chromosome arms below 36-46 Mbp in length. We identified two lamina associated domain subsets through their differential nuclear lamina versus nucleolar positioning in different cell lines which showed distinctive patterns of DNA replication timing and gene expression across all cell lines. Unexpectedly, active, nuclear speckle-associated genomic regions were found near typically repressive nuclear compartments, which is attributable to the close proximity of nuclear speckles and nucleoli in some cell types, and association of centromeres with nuclear speckles in hESCs. Our study points to a more complex and variable nuclear genome organization than suggested by current models, as revealed by our TSA-seq methodology.
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2
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Wittmeier A, Bernhardt M, Robisch AL, Cassini C, Osterhoff M, Salditt T, Köster S. Combined optical fluorescence microscopy and X-ray tomography reveals substructures in cell nuclei in 3D. BIOMEDICAL OPTICS EXPRESS 2022; 13:4954-4969. [PMID: 36187264 PMCID: PMC9484410 DOI: 10.1364/boe.462493] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Revised: 07/08/2022] [Accepted: 07/27/2022] [Indexed: 06/16/2023]
Abstract
The function of a biological cell is fundamentally defined by the structural architecture of packaged DNA in the nucleus. Elucidating information about the packaged DNA is facilitated by high-resolution imaging. Here, we combine and correlate hard X-ray propagation-based phase contrast tomography and visible light confocal microscopy in three dimensions to probe DNA in whole cell nuclei of NIH-3T3 fibroblasts. In this way, unlabeled and fluorescently labeled substructures within the cell are visualized in a complementary manner. Our approach enables the quantification of the electron density, volume and optical fluorescence intensity of nuclear material. By joining all of this information, we are able to spatially localize and physically characterize both active and inactive heterochromatin, euchromatin, pericentric heterochromatin foci and nucleoli.
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Affiliation(s)
- Andrew Wittmeier
- Institute for X-Ray Physics, University of Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Marten Bernhardt
- Institute for X-Ray Physics, University of Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Anna-Lena Robisch
- Institute for X-Ray Physics, University of Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Chiara Cassini
- Institute for X-Ray Physics, University of Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
- Cluster of Excellence “Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells” (MBExC), University of Göttingen, Germany
| | - Markus Osterhoff
- Institute for X-Ray Physics, University of Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - Tim Salditt
- Institute for X-Ray Physics, University of Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
- Cluster of Excellence “Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells” (MBExC), University of Göttingen, Germany
| | - Sarah Köster
- Institute for X-Ray Physics, University of Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
- Cluster of Excellence “Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells” (MBExC), University of Göttingen, Germany
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3
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Belmont AS. Nuclear Compartments: An Incomplete Primer to Nuclear Compartments, Bodies, and Genome Organization Relative to Nuclear Architecture. Cold Spring Harb Perspect Biol 2022; 14:a041268. [PMID: 34400557 PMCID: PMC9248822 DOI: 10.1101/cshperspect.a041268] [Citation(s) in RCA: 38] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
This work reviews nuclear compartments, defined broadly to include distinct nuclear structures, bodies, and chromosome domains. It first summarizes original cytological observations before comparing concepts of nuclear compartments emerging from microscopy versus genomic approaches and then introducing new multiplexed imaging approaches that promise in the future to meld both approaches. I discuss how previous models of radial distribution of chromosomes or the binary division of the genome into A and B compartments are now being refined by the recognition of more complex nuclear compartmentalization. The poorly understood question of how these nuclear compartments are established and maintained is then discussed, including through the modern perspective of phase separation, before moving on to address possible functions of nuclear compartments, using the possible role of nuclear speckles in modulating gene expression as an example. Finally, the review concludes with a discussion of future questions for this field.
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Affiliation(s)
- Andrew S Belmont
- Department of Cell and Developmental Biology, University of Illinois, Urbana-Champaign, Urbana, Illinois 61801, USA
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4
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Brändle F, Frühbauer B, Jagannathan M. Principles and functions of pericentromeric satellite DNA clustering into chromocenters. Semin Cell Dev Biol 2022; 128:26-39. [PMID: 35144860 DOI: 10.1016/j.semcdb.2022.02.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2022] [Revised: 02/03/2022] [Accepted: 02/03/2022] [Indexed: 12/29/2022]
Abstract
Simple non-coding tandem repeats known as satellite DNA are observed widely across eukaryotes. These repeats occupy vast regions at the centromere and pericentromere of chromosomes but their contribution to cellular function has remained incompletely understood. Here, we review the literature on pericentromeric satellite DNA and discuss its organization and functions across eukaryotic species. We specifically focus on chromocenters, DNA-dense nuclear foci that contain clustered pericentromeric satellite DNA repeats from multiple chromosomes. We first discuss chromocenter formation and the roles that epigenetic modifications, satellite DNA transcripts and sequence-specific satellite DNA-binding play in this process. We then review the newly emerging functions of chromocenters in genome encapsulation, the maintenance of cell fate and speciation. We specifically highlight how the rapid divergence of satellite DNA repeats impacts reproductive isolation between closely related species. Together, we underline the importance of this so-called 'junk DNA' in fundamental biological processes.
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Affiliation(s)
- Franziska Brändle
- Institute of Biochemistry, ETH Zürich, Otto-Stern-Weg 3, Zürich CH-8093, Switzerland
| | - Benjamin Frühbauer
- Institute of Biochemistry, ETH Zürich, Otto-Stern-Weg 3, Zürich CH-8093, Switzerland
| | - Madhav Jagannathan
- Institute of Biochemistry, ETH Zürich, Otto-Stern-Weg 3, Zürich CH-8093, Switzerland.
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5
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Pongubala JMR, Murre C. Spatial Organization of Chromatin: Transcriptional Control of Adaptive Immune Cell Development. Front Immunol 2021; 12:633825. [PMID: 33854505 PMCID: PMC8039525 DOI: 10.3389/fimmu.2021.633825] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Accepted: 03/03/2021] [Indexed: 12/11/2022] Open
Abstract
Higher-order spatial organization of the genome into chromatin compartments (permissive and repressive), self-associating domains (TADs), and regulatory loops provides structural integrity and offers diverse gene regulatory controls. In particular, chromatin regulatory loops, which bring enhancer and associated transcription factors in close spatial proximity to target gene promoters, play essential roles in regulating gene expression. The establishment and maintenance of such chromatin loops are predominantly mediated involving CTCF and the cohesin machinery. In recent years, significant progress has been made in revealing how loops are assembled and how they modulate patterns of gene expression. Here we will discuss the mechanistic principles that underpin the establishment of three-dimensional (3D) chromatin structure and how changes in chromatin structure relate to alterations in gene programs that establish immune cell fate.
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Affiliation(s)
| | - Cornelis Murre
- Division of Biological Sciences, University of California, San Diego, La Jolla, CA, United States
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6
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Epigenetic Factors That Control Pericentric Heterochromatin Organization in Mammals. Genes (Basel) 2020; 11:genes11060595. [PMID: 32481609 PMCID: PMC7349813 DOI: 10.3390/genes11060595] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Revised: 05/17/2020] [Accepted: 05/25/2020] [Indexed: 12/11/2022] Open
Abstract
Pericentric heterochromatin (PCH) is a particular form of constitutive heterochromatin that is localized to both sides of centromeres and that forms silent compartments enriched in repressive marks. These genomic regions contain species-specific repetitive satellite DNA that differs in terms of nucleotide sequences and repeat lengths. In spite of this sequence diversity, PCH is involved in many biological phenomena that are conserved among species, including centromere function, the preservation of genome integrity, the suppression of spurious recombination during meiosis, and the organization of genomic silent compartments in the nucleus. PCH organization and maintenance of its repressive state is tightly regulated by a plethora of factors, including enzymes (e.g., DNA methyltransferases, histone deacetylases, and histone methyltransferases), DNA and histone methylation binding factors (e.g., MECP2 and HP1), chromatin remodeling proteins (e.g., ATRX and DAXX), and non-coding RNAs. This evidence helps us to understand how PCH organization is crucial for genome integrity. It then follows that alterations to the molecular signature of PCH might contribute to the onset of many genetic pathologies and to cancer progression. Here, we describe the most recent updates on the molecular mechanisms known to underlie PCH organization and function.
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7
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Grigoryev SA, Popova EY. Attraction of Likenesses: Mechanisms of Self-Association and Compartmentalization of Eukaryotic Chromatin. Mol Biol 2019. [DOI: 10.1134/s0026893319060050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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8
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Ding Y, Zhang B, Payne JL, Song C, Ge Z, Gowda C, Iyer S, Dhanyamraju PK, Dorsam G, Reeves ME, Desai D, Huang S, Payne KJ, Yue F, Dovat S. Ikaros tumor suppressor function includes induction of active enhancers and super-enhancers along with pioneering activity. Leukemia 2019; 33:2720-2731. [PMID: 31073152 PMCID: PMC6842075 DOI: 10.1038/s41375-019-0474-0] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2018] [Revised: 02/15/2019] [Accepted: 03/19/2019] [Indexed: 12/12/2022]
Abstract
Ikaros encodes a transcription factor that functions as a tumor suppressor in T-cell acute lymphoblastic leukemia (T-ALL). The mechanisms through which Ikaros regulates gene expression and cellular proliferation in T-ALL are unknown. Re-introduction of Ikaros into Ikaros-null T-ALL cells resulted in cessation of cellular proliferation and induction of T-cell differentiation. We performed dynamic, global, epigenomic and gene expression analyses to determine the mechanisms of Ikaros tumor suppressor activity. Our results identified novel Ikaros functions in the epigenetic regulation of gene expression: Ikaros directly regulates de novo formation and depletion of enhancers, de novo formation of active enhancers and activation of poised enhancers; Ikaros directly induces the formation of super-enhancers; and Ikaros demonstrates pioneering activity by directly regulating chromatin accessibility. Dynamic analyses demonstrate the long-lasting effects of Ikaros DNA binding on enhancer activation, de novo formation of enhancers and super-enhancers, and chromatin accessibility. Our results establish that Ikaros’ tumor suppressor function occurs via global regulation of the enhancer and super-enhancer landscape and through pioneering activity. Expression analysis identified a large number of novel signaling pathways that are directly regulated by Ikaros and Ikaros-induced enhancers, and that are responsible for the cessation of proliferation and induction of T-cell differentiation in T-ALL cells.
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Affiliation(s)
- Yali Ding
- Depatment of Pediatrics, Pennsylvania State University College of Medicine, Hershey, PA, USA
| | - Bo Zhang
- Department of Biochemistry and Molecular Biology, Pennsylvania State University College of Medicine, Hershey, PA, USA
| | - Jonathon L Payne
- Depatment of Pediatrics, Pennsylvania State University College of Medicine, Hershey, PA, USA.,Loma Linda University School of Medicine, Loma Linda, CA, 92354, USA
| | - Chunhua Song
- Depatment of Pediatrics, Pennsylvania State University College of Medicine, Hershey, PA, USA
| | - Zheng Ge
- Department of Hematology, Zhongda Hospital Southeast University, Institute of Hematology Southeast University, 210009, Nanjing, China
| | - Chandrika Gowda
- Depatment of Pediatrics, Pennsylvania State University College of Medicine, Hershey, PA, USA
| | - Soumya Iyer
- Depatment of Pediatrics, Pennsylvania State University College of Medicine, Hershey, PA, USA
| | - Pavan K Dhanyamraju
- Depatment of Pediatrics, Pennsylvania State University College of Medicine, Hershey, PA, USA
| | - Glenn Dorsam
- Department of Microbiological Sciences, North Dakota State University, Fargo, ND, 58102, USA
| | - Mark E Reeves
- Loma Linda University School of Medicine, Loma Linda, CA, 92354, USA
| | - Dhimant Desai
- Department of Pharmacology, Pennsylvania State University College of Medicine, Hershey, PA, USA
| | - Suming Huang
- Depatment of Pediatrics, Pennsylvania State University College of Medicine, Hershey, PA, USA
| | - Kimberly J Payne
- Loma Linda University School of Medicine, Loma Linda, CA, 92354, USA
| | - Feng Yue
- Department of Biochemistry and Molecular Biology, Pennsylvania State University College of Medicine, Hershey, PA, USA.
| | - Sinisa Dovat
- Depatment of Pediatrics, Pennsylvania State University College of Medicine, Hershey, PA, USA. .,Department of Biochemistry and Molecular Biology, Pennsylvania State University College of Medicine, Hershey, PA, USA.
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10
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Naik AK, Byrd AT, Lucander ACK, Krangel MS. Hierarchical assembly and disassembly of a transcriptionally active RAG locus in CD4 +CD8 + thymocytes. J Exp Med 2018; 216:231-243. [PMID: 30545902 PMCID: PMC6314527 DOI: 10.1084/jem.20181402] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Revised: 10/29/2018] [Accepted: 11/21/2018] [Indexed: 01/17/2023] Open
Abstract
Naik et al. show that GATA3, Runx1, and E2A are essential for hierarchical assembly of a transcriptionally active RAG locus chromatin hub in CD4+CD8+ thymocytes. Signal-dependent down-regulation of RAG expression is associated with hub disassembly and depends on Ikaros. Expression of Rag1 and Rag2 is tightly regulated in developing T cells to mediate TCR gene assembly. Here we have investigated the molecular mechanisms governing the assembly and disassembly of a transcriptionally active RAG locus chromatin hub in CD4+CD8+ thymocytes. Rag1 and Rag2 gene expression in CD4+CD8+ thymocytes depends on Rag1 and Rag2 promoter activation by a distant antisilencer element (ASE). We identify GATA3 and E2A as critical regulators of the ASE, and Runx1 and E2A as critical regulators of the Rag1 promoter. We reveal hierarchical assembly of a transcriptionally active chromatin hub containing the ASE and RAG promoters, with Rag2 recruitment and expression dependent on assembly of a functional ASE–Rag1 framework. Finally, we show that signal-dependent down-regulation of RAG gene expression in CD4+CD8+ thymocytes depends on Ikaros and occurs with disassembly of the RAG locus chromatin hub. Our results provide important new insights into the molecular mechanisms that orchestrate RAG gene expression in developing T cells.
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Affiliation(s)
- Abani Kanta Naik
- Department of Immunology, Duke University Medical Center, Durham, NC
| | - Aaron T Byrd
- Department of Immunology, Duke University Medical Center, Durham, NC
| | | | - Michael S Krangel
- Department of Immunology, Duke University Medical Center, Durham, NC
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11
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Szczesny SE, Mauck RL. The Nuclear Option: Evidence Implicating the Cell Nucleus in Mechanotransduction. J Biomech Eng 2017; 139:2592356. [PMID: 27918797 DOI: 10.1115/1.4035350] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Indexed: 02/06/2023]
Abstract
Biophysical stimuli presented to cells via microenvironmental properties (e.g., alignment and stiffness) or external forces have a significant impact on cell function and behavior. Recently, the cell nucleus has been identified as a mechanosensitive organelle that contributes to the perception and response to mechanical stimuli. However, the specific mechanotransduction mechanisms that mediate these effects have not been clearly established. Here, we offer a comprehensive review of the evidence supporting (and refuting) three hypothetical nuclear mechanotransduction mechanisms: physical reorganization of chromatin, signaling at the nuclear envelope, and altered cytoskeletal structure/tension due to nuclear remodeling. Our goal is to provide a reference detailing the progress that has been made and the areas that still require investigation regarding the role of nuclear mechanotransduction in cell biology. Additionally, we will briefly discuss the role that mathematical models of cell mechanics can play in testing these hypotheses and in elucidating how biophysical stimulation of the nucleus drives changes in cell behavior. While force-induced alterations in signaling pathways involving lamina-associated polypeptides (LAPs) (e.g., emerin and histone deacetylase 3 (HDAC3)) and transcription factors (TFs) located at the nuclear envelope currently appear to be the most clearly supported mechanism of nuclear mechanotransduction, additional work is required to examine this process in detail and to more fully test alternative mechanisms. The combination of sophisticated experimental techniques and advanced mathematical models is necessary to enhance our understanding of the role of the nucleus in the mechanotransduction processes driving numerous critical cell functions.
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Affiliation(s)
- Spencer E Szczesny
- Department of Orthopaedic Surgery, University of Pennsylvania, 424 Stemmler Hall, 36th Street and Hamilton Walk, Philadelphia, PA 19104; Translational Musculoskeletal Research Center, Corporal Michael J. Crescenz Veterans Affairs Medical Center, 3900 Woodland Avenue, Philadelphia, PA 19104
| | - Robert L Mauck
- Department of Orthopaedic Surgery, University of Pennsylvania, 424 Stemmler Hall, 36th Street and Hamilton Walk, Philadelphia, PA 19104; Translational Musculoskeletal Research Center, Corporal Michael J. Crescenz Veterans Affairs Medical Center, 3900 Woodland Avenue, Philadelphia, PA 19104;Department of Bioengineering, University of Pennsylvania, 240 Skirkanich Hall, 210 South 33rd Street, Philadelphia, PA 19104 e-mail:
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12
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Coyle KM, Boudreau JE, Marcato P. Genetic Mutations and Epigenetic Modifications: Driving Cancer and Informing Precision Medicine. BIOMED RESEARCH INTERNATIONAL 2017; 2017:9620870. [PMID: 28685150 PMCID: PMC5480027 DOI: 10.1155/2017/9620870] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/07/2016] [Revised: 04/06/2017] [Accepted: 05/10/2017] [Indexed: 12/21/2022]
Abstract
Cancer treatment is undergoing a significant revolution from "one-size-fits-all" cytotoxic therapies to tailored approaches that precisely target molecular alterations. Precision strategies for drug development and patient stratification, based on the molecular features of tumors, are the next logical step in a long history of approaches to cancer therapy. In this review, we discuss the history of cancer treatment from generic natural extracts and radical surgical procedures to site-specific and combinatorial treatment regimens, which have incrementally improved patient outcomes. We discuss the related contributions of genetics and epigenetics to cancer progression and the response to targeted therapies and identify challenges and opportunities for the success of precision medicine. The identification of patients who will benefit from targeted therapies is more complex than simply identifying patients whose tumors harbour the targeted aberration, and intratumoral heterogeneity makes it difficult to determine if a precision therapy is successful during treatment. This heterogeneity enables tumors to develop resistance to targeted approaches; therefore, the rational combination of therapeutic agents will limit the threat of acquired resistance to therapeutic success. By incorporating the view of malignant transformation modulated by networks of genetic and epigenetic interactions, molecular strategies will enable precision medicine for effective treatment across cancer subtypes.
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Affiliation(s)
| | - Jeanette E. Boudreau
- Department of Pathology, Dalhousie University, Halifax, NS, Canada
- Department of Microbiology & Immunology, Dalhousie University, Halifax, NS, Canada
| | - Paola Marcato
- Department of Pathology, Dalhousie University, Halifax, NS, Canada
- Department of Microbiology & Immunology, Dalhousie University, Halifax, NS, Canada
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13
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Denker A, de Laat W. The second decade of 3C technologies: detailed insights into nuclear organization. Genes Dev 2017; 30:1357-82. [PMID: 27340173 PMCID: PMC4926860 DOI: 10.1101/gad.281964.116] [Citation(s) in RCA: 225] [Impact Index Per Article: 32.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The relevance of three-dimensional (3D) genome organization for transcriptional regulation and thereby for cellular fate at large is now widely accepted. Our understanding of the fascinating architecture underlying this function is based on microscopy studies as well as the chromosome conformation capture (3C) methods, which entered the stage at the beginning of the millennium. The first decade of 3C methods rendered unprecedented insights into genome topology. Here, we provide an update of developments and discoveries made over the more recent years. As we discuss, established and newly developed experimental and computational methods enabled identification of novel, functionally important chromosome structures. Regulatory and architectural chromatin loops throughout the genome are being cataloged and compared between cell types, revealing tissue invariant and developmentally dynamic loops. Architectural proteins shaping the genome were disclosed, and their mode of action is being uncovered. We explain how more detailed insights into the 3D genome increase our understanding of transcriptional regulation in development and misregulation in disease. Finally, to help researchers in choosing the approach best tailored for their specific research question, we explain the differences and commonalities between the various 3C-derived methods.
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Affiliation(s)
- Annette Denker
- Hubrecht Institute-Koninklijke Nederlandse Akademie van Wetenschappen (KNAW) and University Medical Center Utrecht, 3584CT Utrecht, the Netherlands
| | - Wouter de Laat
- Hubrecht Institute-Koninklijke Nederlandse Akademie van Wetenschappen (KNAW) and University Medical Center Utrecht, 3584CT Utrecht, the Netherlands
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14
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Liang Z, Brown KE, Carroll T, Taylor B, Vidal IF, Hendrich B, Rueda D, Fisher AG, Merkenschlager M. A high-resolution map of transcriptional repression. eLife 2017; 6. [PMID: 28318487 PMCID: PMC5373822 DOI: 10.7554/elife.22767] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Accepted: 03/15/2017] [Indexed: 11/20/2022] Open
Abstract
Turning genes on and off is essential for development and homeostasis, yet little is known about the sequence and causal role of chromatin state changes during the repression of active genes. This is surprising, as defective gene silencing underlies developmental abnormalities and disease. Here we delineate the sequence and functional contribution of transcriptional repression mechanisms at high temporal resolution. Inducible entry of the NuRD-interacting transcriptional regulator Ikaros into mouse pre-B cell nuclei triggered immediate binding to target gene promoters. Rapid RNAP2 eviction, transcriptional shutdown, nucleosome invasion, and reduced transcriptional activator binding required chromatin remodeling by NuRD-associated Mi2beta/CHD4, but were independent of HDAC activity. Histone deacetylation occurred after transcriptional repression. Nevertheless, HDAC activity contributed to stable gene silencing. Hence, high resolution mapping of transcriptional repression reveals complex and interdependent mechanisms that underpin rapid transitions between transcriptional states, and elucidates the temporal order, functional role and mechanistic separation of NuRD-associated enzymatic activities. DOI:http://dx.doi.org/10.7554/eLife.22767.001
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Affiliation(s)
- Ziwei Liang
- Lymphocyte Development Group, MRC London Institute of Medical Sciences, Faculty of Medicine, Imperial College London, London, United Kingdom.,Epigenetics Section, MRC London Institute of Medical Sciences, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - Karen E Brown
- Lymphocyte Development Group, MRC London Institute of Medical Sciences, Faculty of Medicine, Imperial College London, London, United Kingdom.,Epigenetics Section, MRC London Institute of Medical Sciences, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - Thomas Carroll
- Epigenetics Section, MRC London Institute of Medical Sciences, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - Benjamin Taylor
- Lymphocyte Development Group, MRC London Institute of Medical Sciences, Faculty of Medicine, Imperial College London, London, United Kingdom.,Epigenetics Section, MRC London Institute of Medical Sciences, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - Isabel Ferreirós Vidal
- Lymphocyte Development Group, MRC London Institute of Medical Sciences, Faculty of Medicine, Imperial College London, London, United Kingdom.,Epigenetics Section, MRC London Institute of Medical Sciences, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - Brian Hendrich
- Wellcome Trust - Medical Research Council Stem Cell Institute, Cambridge, United Kingdom.,Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
| | - David Rueda
- Single Molecule Imaging Group, MRC London Institute of Medical Sciences, Faculty of Medicine, Imperial College London, London, United Kingdom.,Integrative Biology Section, MRC London Institute of Medical Sciences, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - Amanda G Fisher
- Lymphocyte Development Group, MRC London Institute of Medical Sciences, Faculty of Medicine, Imperial College London, London, United Kingdom.,Epigenetics Section, MRC London Institute of Medical Sciences, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - Matthias Merkenschlager
- Lymphocyte Development Group, MRC London Institute of Medical Sciences, Faculty of Medicine, Imperial College London, London, United Kingdom.,Epigenetics Section, MRC London Institute of Medical Sciences, Faculty of Medicine, Imperial College London, London, United Kingdom.,Integrative Biology Section, MRC London Institute of Medical Sciences, Faculty of Medicine, Imperial College London, London, United Kingdom
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15
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Lomonte P. Herpesvirus Latency: On the Importance of Positioning Oneself. ADVANCES IN ANATOMY, EMBRYOLOGY, AND CELL BIOLOGY 2017; 223:95-117. [PMID: 28528441 DOI: 10.1007/978-3-319-53168-7_5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The nucleus is composed of multiple compartments and domains, which directly or indirectly influence many cellular processes including gene expression, RNA splicing and maturation, protein post-translational modifications, and chromosome segregation. Nuclear-replicating viruses, especially herpesviruses, have co-evolved with the cell, adopting strategies to counteract and eventually hijack this hostile environment for their own benefit. This allows them to persist in the host for the entire life of an individual and to ensure their maintenance in the target species. Herpesviruses establish latency in dividing or postmitotic cells from which they can efficiently reactivate after sometimes years of a seemingly dormant state. Therefore, herpesviruses circumvent the threat of permanent silencing by reactivating their dormant genomes just enough to escape extinction, but not too much to avoid life-threatening damage to the host. In addition, herpesviruses that establish latency in dividing cells must adopt strategies to maintain their genomes in the daughter cells to avoid extinction by dilution of their genomes following multiple cell divisions. From a biochemical point of view, reactivation and maintenance of viral genomes in dividing cells occur successfully because the viral genomes interact with the nuclear architecture in a way that allows the genomes to be transmitted faithfully and to benefit from the nuclear micro-environments that allow reactivation following specific stimuli. Therefore, spatial positioning of the viral genomes within the nucleus is likely to be essential for the success of the latent infection and, beyond that, for the maintenance of herpesviruses in their respective hosts.
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Affiliation(s)
- Patrick Lomonte
- Univ Lyon, Université Claude Bernard Lyon 1, CNRS UMR-5310, INSERM U-1217, LabEx DEVweCAN, Institut NeuroMyoGène (INMG), team Chromatin Assembly, Nuclear Domains, Virus, 69008, Lyon, France.
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16
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Meaburn KJ. Spatial Genome Organization and Its Emerging Role as a Potential Diagnosis Tool. Front Genet 2016; 7:134. [PMID: 27507988 PMCID: PMC4961005 DOI: 10.3389/fgene.2016.00134] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Accepted: 07/13/2016] [Indexed: 12/12/2022] Open
Abstract
In eukaryotic cells the genome is highly spatially organized. Functional relevance of higher order genome organization is implied by the fact that specific genes, and even whole chromosomes, alter spatial position in concert with functional changes within the nucleus, for example with modifications to chromatin or transcription. The exact molecular pathways that regulate spatial genome organization and the full implication to the cell of such an organization remain to be determined. However, there is a growing realization that the spatial organization of the genome can be used as a marker of disease. While global genome organization patterns remain largely conserved in disease, some genes and chromosomes occupy distinct nuclear positions in diseased cells compared to their normal counterparts, with the patterns of reorganization differing between diseases. Importantly, mapping the spatial positioning patterns of specific genomic loci can distinguish cancerous tissue from benign with high accuracy. Genome positioning is an attractive novel biomarker since additional quantitative biomarkers are urgently required in many cancer types. Current diagnostic techniques are often subjective and generally lack the ability to identify aggressive cancer from indolent, which can lead to over- or under-treatment of patients. Proof-of-principle for the use of genome positioning as a diagnostic tool has been provided based on small scale retrospective studies. Future large-scale studies are required to assess the feasibility of bringing spatial genome organization-based diagnostics to the clinical setting and to determine if the positioning patterns of specific loci can be useful biomarkers for cancer prognosis. Since spatial reorganization of the genome has been identified in multiple human diseases, it is likely that spatial genome positioning patterns as a diagnostic biomarker may be applied to many diseases.
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Affiliation(s)
- Karen J. Meaburn
- Cell Biology of Genomes Group, National Cancer Institute, National Institutes of HealthBethesda, MD, USA
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Della Ragione F, Vacca M, Fioriniello S, Pepe G, D'Esposito M. MECP2, a multi-talented modulator of chromatin architecture. Brief Funct Genomics 2016; 15:420-431. [PMID: 27296483 DOI: 10.1093/bfgp/elw023] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
It has been a long trip from 1992, the year of the discovery of MECP2, to the present day. What is surprising is that some of the pivotal roles of MeCP2 were already postulated at that time, such as repression of inappropriate expression from repetitive elements and the regulation of pericentric heterochromatin condensation. However, MeCP2 performs many more functions. MeCP2 is a reader of epigenetic information contained in methylated (and hydroxymethylated) DNA, moving from the 'classical' CpG doublet to the more complex view addressed by the non-CpG methylation, which is a feature of the postnatal brain. MECP2 is a transcriptional repressor, although when it forms complexes with the appropriate molecules, it can become a transcriptional activator. For all of these aspects, Rett syndrome, which is caused by MECP2 mutations, is considered a paradigmatic example of a 'chromatin disorder'. Even if the hunt for bona-fide MECP2 target genes is far from concluded today, the role of MeCP2 in the maintenance of chromatin architecture appears to be clearly established. Taking a cue from the non-scientific literature, we can firmly attest that MeCP2 is a player with 'a great future behind it'*.*V. Gassmann 'Un grande avvenire dietro le spalle'. TEA Eds.
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18
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Toneatto J, Charó NL, Galigniana NM, Piwien-Pilipuk G. Adipogenesis is under surveillance of Hsp90 and the high molecular weight Immunophilin FKBP51. Adipocyte 2015; 4:239-47. [PMID: 26451279 DOI: 10.1080/21623945.2015.1049401] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/05/2015] [Revised: 04/30/2015] [Accepted: 05/01/2015] [Indexed: 01/21/2023] Open
Abstract
Adipose tissue plays a central role in the control of energy balance as well as in the maintenance of metabolic homeostasis. It was not until recently that the first evidences of the role of heat shock protein (Hsp) 90 and high molecular weight immunophilin FKBP51 have been described in the process of adipocyte differentiation. Recent reports describe their role in the regulation of PPARγ, a key transcription factor in the control of adipogenesis and the maintenance of the adipocyte phenotype. In addition, novel roles have been uncovered for FKBP51 in the organization of the architecture of the nucleus through its participation in the reorganization of the nuclear lamina. Therefore, the aim of this review is to integrate and discuss the recent advances in the field, with special emphasis on the roles of Hsp90 and FKBP51 in the process of adipocyte differentiation.
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Outters P, Jaeger S, Zaarour N, Ferrier P. Long-Range Control of V(D)J Recombination & Allelic Exclusion: Modeling Views. Adv Immunol 2015; 128:363-413. [PMID: 26477371 DOI: 10.1016/bs.ai.2015.08.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Allelic exclusion of immunoglobulin (Ig) and T-cell receptor (TCR) genes ensures the development of B and T lymphocytes operating under the mode of clonal selection. This phenomenon associates asynchronous V(D)J recombination events at Ig or TCR alleles and inhibitory feedback control. Despite years of intense research, however, the mechanisms that sustain asymmetric choice in random Ig/TCR dual allele usage and the production of Ig/TCR monoallelic expressing B and T lymphocytes remain unclear and open for debate. In this chapter, we first recapitulate the biological evidence that almost from the start appeared to link V(D)J recombination and allelic exclusion. We review the theoretical models previously proposed to explain this connection. Finally, we introduce our own mathematical modeling views based on how the developmental dynamics of individual lymphoid cells combine to sustain allelic exclusion.
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Affiliation(s)
- Pernelle Outters
- Centre d'Immunologie de Marseille-Luminy, Aix-Marseille Université UM2, Inserm, U1104, CNRS UMR7280, 13288 Marseille, France
| | - Sébastien Jaeger
- Centre d'Immunologie de Marseille-Luminy, Aix-Marseille Université UM2, Inserm, U1104, CNRS UMR7280, 13288 Marseille, France
| | - Nancy Zaarour
- Centre d'Immunologie de Marseille-Luminy, Aix-Marseille Université UM2, Inserm, U1104, CNRS UMR7280, 13288 Marseille, France
| | - Pierre Ferrier
- Centre d'Immunologie de Marseille-Luminy, Aix-Marseille Université UM2, Inserm, U1104, CNRS UMR7280, 13288 Marseille, France.
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20
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Proudhon C, Hao B, Raviram R, Chaumeil J, Skok JA. Long-Range Regulation of V(D)J Recombination. Adv Immunol 2015; 128:123-82. [PMID: 26477367 DOI: 10.1016/bs.ai.2015.07.003] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Given their essential role in adaptive immunity, antigen receptor loci have been the focus of analysis for many years and are among a handful of the most well-studied genes in the genome. Their investigation led initially to a detailed knowledge of linear structure and characterization of regulatory elements that confer control of their rearrangement and expression. However, advances in DNA FISH and imaging combined with new molecular approaches that interrogate chromosome conformation have led to a growing appreciation that linear structure is only one aspect of gene regulation and in more recent years, the focus has switched to analyzing the impact of locus conformation and nuclear organization on control of recombination. Despite decades of work and intense effort from numerous labs, we are still left with an incomplete picture of how the assembly of antigen receptor loci is regulated. This chapter summarizes our advances to date and points to areas that need further investigation.
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Affiliation(s)
- Charlotte Proudhon
- Department of Pathology, New York University School of Medicine, New York, USA
| | - Bingtao Hao
- Department of Pathology, New York University School of Medicine, New York, USA
| | - Ramya Raviram
- Department of Pathology, New York University School of Medicine, New York, USA
| | - Julie Chaumeil
- Institut Curie, CNRS UMR3215, INSERM U934, Paris, France
| | - Jane A Skok
- Department of Pathology, New York University School of Medicine, New York, USA.
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21
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Wijchers PJ, Geeven G, Eyres M, Bergsma AJ, Janssen M, Verstegen M, Zhu Y, Schell Y, Vermeulen C, de Wit E, de Laat W. Characterization and dynamics of pericentromere-associated domains in mice. Genome Res 2015; 25:958-69. [PMID: 25883320 PMCID: PMC4484393 DOI: 10.1101/gr.186643.114] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2014] [Accepted: 04/13/2015] [Indexed: 01/01/2023]
Abstract
Despite recent progress in genome topology knowledge, the role of repeats, which make up the majority of mammalian genomes, remains elusive. Satellite repeats are highly abundant sequences that cluster around centromeres, attract pericentromeric heterochromatin, and aggregate into nuclear chromocenters. These nuclear landmark structures are assumed to form a repressive compartment in the nucleus to which genes are recruited for silencing. We have designed a strategy for genome-wide identification of pericentromere-associated domains (PADs) in different mouse cell types. The ∼1000 PADs and non-PADs have similar chromatin states in embryonic stem cells, but during lineage commitment, chromocenters progressively associate with constitutively inactive genomic regions at the nuclear periphery. This suggests that PADs are not actively recruited to chromocenters, but that chromocenters are themselves attracted to inactive chromatin compartments. However, we also found that experimentally induced proximity of an active locus to chromocenters was sufficient to cause gene repression. Collectively, our data suggest that rather than driving nuclear organization, pericentromeric satellite repeats mostly co-segregate with inactive genomic regions into nuclear compartments where they can contribute to stable maintenance of the repressed status of proximal chromosomal regions.
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Affiliation(s)
- Patrick J Wijchers
- Hubrecht Institute-KNAW & University Medical Center Utrecht, 3584 CT Utrecht, The Netherlands
| | - Geert Geeven
- Hubrecht Institute-KNAW & University Medical Center Utrecht, 3584 CT Utrecht, The Netherlands
| | - Michael Eyres
- Hubrecht Institute-KNAW & University Medical Center Utrecht, 3584 CT Utrecht, The Netherlands
| | - Atze J Bergsma
- Hubrecht Institute-KNAW & University Medical Center Utrecht, 3584 CT Utrecht, The Netherlands
| | - Mark Janssen
- Hubrecht Institute-KNAW & University Medical Center Utrecht, 3584 CT Utrecht, The Netherlands
| | - Marjon Verstegen
- Hubrecht Institute-KNAW & University Medical Center Utrecht, 3584 CT Utrecht, The Netherlands
| | - Yun Zhu
- Hubrecht Institute-KNAW & University Medical Center Utrecht, 3584 CT Utrecht, The Netherlands
| | - Yori Schell
- Hubrecht Institute-KNAW & University Medical Center Utrecht, 3584 CT Utrecht, The Netherlands
| | - Carlo Vermeulen
- Hubrecht Institute-KNAW & University Medical Center Utrecht, 3584 CT Utrecht, The Netherlands
| | - Elzo de Wit
- Hubrecht Institute-KNAW & University Medical Center Utrecht, 3584 CT Utrecht, The Netherlands
| | - Wouter de Laat
- Hubrecht Institute-KNAW & University Medical Center Utrecht, 3584 CT Utrecht, The Netherlands
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22
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Myosin VI regulates gene pairing and transcriptional pause release in T cells. Proc Natl Acad Sci U S A 2015; 112:E1587-93. [PMID: 25770220 DOI: 10.1073/pnas.1502461112] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Naive CD4 T cells differentiate into several effector lineages, which generate a stronger and more rapid response to previously encountered immunological challenges. Although effector function is a key feature of adaptive immunity, the molecular basis of this process is poorly understood. Here, we investigated the spatiotemporal regulation of cytokine gene expression in resting and restimulated effector T helper 1 (Th1) cells. We found that the Lymphotoxin (LT)/TNF alleles, which encode TNF-α, were closely juxtaposed shortly after T-cell receptor (TCR) engagement, when transcription factors are limiting. Allelic pairing required a nuclear myosin, myosin VI, which is rapidly recruited to the LT/TNF locus upon restimulation. Furthermore, transcription was paused at the TNF locus and other related genes in resting Th1 cells and released in a myosin VI-dependent manner following activation. We propose that homologous pairing and myosin VI-mediated transcriptional pause release account for the rapid and efficient expression of genes induced by an external stimulus.
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23
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Chromatin-Driven Behavior of Topologically Associating Domains. J Mol Biol 2015; 427:608-25. [DOI: 10.1016/j.jmb.2014.09.013] [Citation(s) in RCA: 82] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2014] [Revised: 09/17/2014] [Accepted: 09/23/2014] [Indexed: 12/19/2022]
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24
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Toneatto J, Charó NL, Naselli A, Muñoz-Bernart M, Lombardi A, Piwien-Pilipuk G. Corticosteroid Receptors, Their Chaperones and Cochaperones: How Do They Modulate Adipogenesis? NUCLEAR RECEPTOR RESEARCH 2014. [DOI: 10.11131/2014/101092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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25
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Bian Q, Khanna N, Alvikas J, Belmont AS. β-Globin cis-elements determine differential nuclear targeting through epigenetic modifications. ACTA ACUST UNITED AC 2013; 203:767-83. [PMID: 24297746 PMCID: PMC3857487 DOI: 10.1083/jcb.201305027] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Multiple cis-elements surrounding the β-globin gene locus combine to target this locus to the nuclear periphery through at least two different epigenetic marks. Increasing evidence points to nuclear compartmentalization as a contributing mechanism for gene regulation, yet mechanisms for compartmentalization remain unclear. In this paper, we use autonomous targeting of bacterial artificial chromosome (BAC) transgenes to reveal cis requirements for peripheral targeting. Three peripheral targeting regions (PTRs) within an HBB BAC bias a competition between pericentric versus peripheral heterochromatin targeting toward the nuclear periphery, which correlates with increased H3K9me3 across the β-globin gene cluster and locus control region. Targeting to both heterochromatin compartments is dependent on Suv39H-mediated H3K9me3 methylation. In different chromosomal contexts, PTRs confer no targeting, targeting to pericentric heterochromatin, or targeting to the periphery. A combination of fluorescent in situ hybridization, BAC transgenesis, and knockdown experiments reveals that peripheral tethering of the endogenous HBB locus depends both on Suv39H-mediated H3K9me3 methylation over hundreds of kilobases surrounding HBB and on G9a-mediated H3K9me2 methylation over flanking sequences in an adjacent lamin-associated domain. Our results demonstrate that multiple cis-elements regulate the overall balance of specific epigenetic marks and peripheral gene targeting.
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Affiliation(s)
- Qian Bian
- Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801
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26
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Insights into chromatin structure and dynamics in plants. BIOLOGY 2013; 2:1378-410. [PMID: 24833230 PMCID: PMC4009787 DOI: 10.3390/biology2041378] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/30/2013] [Revised: 11/15/2013] [Accepted: 11/18/2013] [Indexed: 11/17/2022]
Abstract
The packaging of chromatin into the nucleus of a eukaryotic cell requires an extraordinary degree of compaction and physical organization. In recent years, it has been shown that this organization is dynamically orchestrated to regulate responses to exogenous stimuli as well as to guide complex cell-type-specific developmental programs. Gene expression is regulated by the compartmentalization of functional domains within the nucleus, by distinct nucleosome compositions accomplished via differential modifications on the histone tails and through the replacement of core histones by histone variants. In this review, we focus on these aspects of chromatin organization and discuss novel approaches such as live cell imaging and photobleaching as important tools likely to give significant insights into our understanding of the very dynamic nature of chromatin and chromatin regulatory processes. We highlight the contribution plant studies have made in this area showing the potential advantages of plants as models in understanding this fundamental aspect of biology.
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27
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Yokota T, Sudo T, Ishibashi T, Doi Y, Ichii M, Orirani K, Kanakura Y. Complementary regulation of early B-lymphoid differentiation by genetic and epigenetic mechanisms. Int J Hematol 2013; 98:382-9. [PMID: 23999941 DOI: 10.1007/s12185-013-1424-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2013] [Revised: 08/21/2013] [Accepted: 08/23/2013] [Indexed: 02/02/2023]
Abstract
Although B lymphopoiesis is one of the best-defined paradigms in cell differentiation, our knowledge of the regulatory mechanisms underlying its earliest processes, in which hematopoietic stem cells (HSCs) enter the B lineage, is limited. However, recent methodological advances in sorting progenitor cells and monitoring their epigenetic features have increased our understanding of HSC activities. It is now known that even the highly enriched HSC fraction is heterogeneous in terms of lymphopoietic potential. While surface markers and reporter proteins provide information on the sequential differentiation of B-lineage progenitors, complex interactions between transcription factors have also been shown to play a major role in this process. Epigenetic regulation of histones, nucleosomes, and chromatin appears to play a crucial background role in this elaborate transcription network. In this review, we summarize recent findings on the physiological processes of early B-lineage differentiation, which provides a new paradigm for understanding the harmonious action of genetic and epigenetic mechanisms.
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Affiliation(s)
- Takafumi Yokota
- Department of Hematology and Oncology, Osaka University Graduate School of Medicine, 2-2 Yamada-oka, Suita, Osaka, 565-0871, Japan,
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28
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Ritland Politz JC, Scalzo D, Groudine M. Something silent this way forms: the functional organization of the repressive nuclear compartment. Annu Rev Cell Dev Biol 2013; 29:241-70. [PMID: 23834025 PMCID: PMC3999972 DOI: 10.1146/annurev-cellbio-101512-122317] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The repressive compartment of the nucleus is comprised primarily of telomeric and centromeric regions, the silent portion of ribosomal RNA genes, the majority of transposable element repeats, and facultatively repressed genes specific to different cell types. This compartment localizes into three main regions: the peripheral heterochromatin, perinucleolar heterochromatin, and pericentromeric heterochromatin. Both chromatin remodeling proteins and transcription of noncoding RNAs are involved in maintenance of repression in these compartments. Global reorganization of the repressive compartment occurs at each cell division, during early development, and during terminal differentiation. Differential action of chromatin remodeling complexes and boundary element looping activities are involved in mediating these organizational changes. We discuss the evidence that heterochromatin formation and compartmentalization may drive nuclear organization.
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Affiliation(s)
| | - David Scalzo
- Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109
| | - Mark Groudine
- Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109
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29
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Wei Z, Huang D, Gao F, Chang WH, An W, Coetzee GA, Wang K, Lu W. Biological implications and regulatory mechanisms of long-range chromosomal interactions. J Biol Chem 2013; 288:22369-77. [PMID: 23779110 DOI: 10.1074/jbc.r113.485292] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Development of high-throughput sequencing-based methods has enabled us to examine nuclear architecture at unprecedented resolution, allowing further examination of the function of long-range chromosomal interactions. Here, we review methods used to investigate novel long-range chromosomal interactions and genome-wide organization of chromatin. We further discuss transcriptional activation and silencing in relation to organization and positioning of gene loci and regulation of chromatin organization through protein complexes and noncoding RNAs.
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Affiliation(s)
- Zong Wei
- Eli and Edythe Broad Center for Regenerative Medicine and Stem Cell Research, Keck School of Medicine, University of Southern California, Los Angeles, California 90033, USA
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30
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Mehta I, Chakraborty S, Rao BJ. IMACULAT - an open access package for the quantitative analysis of chromosome localization in the nucleus. PLoS One 2013; 8:e61386. [PMID: 23577217 PMCID: PMC3620108 DOI: 10.1371/journal.pone.0061386] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2012] [Accepted: 03/07/2013] [Indexed: 01/16/2023] Open
Abstract
The alteration in the location of the chromosomes within the nucleus upon action of internal or external stimuli has been implicated in altering genome function. The effect of stimuli at a whole genome level is studied by using two-dimensional fluorescence in situ hybridization (FISH) to delineate whole chromosome territories within a cell nucleus, followed by a quantitative analysis of the spatial distribution of the chromosome. However, to the best of our knowledge, open access software capable of quantifying spatial distribution of whole chromosomes within cell nucleus is not available. In the current work, we present a software package that computes localization of whole chromosomes - Image Analysis of Chromosomes for computing localization (IMACULAT). We partition the nucleus into concentric elliptical compartments of equal area and the variance in the quantity of any chromosome in these shells is used to determine its localization in the nucleus. The images are pre-processed to remove the smudges outside the cell boundary. Automation allows high throughput analysis for deriving statistics. Proliferating normal human dermal fibroblasts were subjected to standard a two-dimensional FISH to delineate territories for all human chromosomes. Approximately 100 images from each chromosome were analyzed using IMACULAT. The analysis corroborated that these chromosome territories have non-random gene density based organization within the interphase nuclei of human fibroblasts. The ImageMagick Perl API has been used for pre-processing the images. The source code is made available at www.sanchak.com/imaculat.html.
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Affiliation(s)
- Ishita Mehta
- Department of Biological Sciences, Tata Institute of Fundamental Research, Mumbai, India
| | - Sandeep Chakraborty
- Department of Biological Sciences, Tata Institute of Fundamental Research, Mumbai, India
| | - Basuthkar J. Rao
- Department of Biological Sciences, Tata Institute of Fundamental Research, Mumbai, India
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31
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Chaumeil J, Micsinai M, Ntziachristos P, Deriano L, Wang JMH, Ji Y, Nora EP, Rodesch MJ, Jeddeloh JA, Aifantis I, Kluger Y, Schatz DG, Skok JA. Higher-order looping and nuclear organization of Tcra facilitate targeted rag cleavage and regulated rearrangement in recombination centers. Cell Rep 2013; 3:359-70. [PMID: 23416051 DOI: 10.1016/j.celrep.2013.01.024] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2012] [Revised: 01/01/2013] [Accepted: 01/16/2013] [Indexed: 11/16/2022] Open
Abstract
V(D)J recombination is essential for generating a diverse array of B and T cell receptors that can recognize and combat foreign antigens. As with any recombination event, tight control is essential to prevent the occurrence of genetic anomalies that drive cellular transformation. One important aspect of regulation is directed targeting of the RAG recombinase. Indeed, RAG accumulates at the 3' end of individual antigen receptor loci poised for rearrangement; however, it is not known whether focal binding is involved in regulating cleavage, and what mechanisms lead to enrichment of RAG in this region. Here, we show that monoallelic looping out of the 3' end of the T cell receptor α (Tcra) locus, coupled with transcription and increased chromatin/nuclear accessibility, is linked to focal RAG binding and ATM-mediated regulation of monoallelic cleavage on looped-out 3' regions. Our data identify higher-order loop formation as a key determinant of directed RAG targeting and the maintenance of genome stability.
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Affiliation(s)
- Julie Chaumeil
- Department of Pathology, New York University School of Medicine, New York, NY 10016, USA
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32
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Chaumeil J, Micsinai M, Skok JA. Combined immunofluorescence and DNA FISH on 3D-preserved interphase nuclei to study changes in 3D nuclear organization. J Vis Exp 2013:e50087. [PMID: 23407477 DOI: 10.3791/50087] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Fluorescent in situ hybridization using DNA probes on 3-dimensionally preserved nuclei followed by 3D confocal microscopy (3D DNA FISH) represents the most direct way to visualize the location of gene loci, chromosomal sub-regions or entire territories in individual cells. This type of analysis provides insight into the global architecture of the nucleus as well as the behavior of specific genomic loci and regions within the nuclear space. Immunofluorescence, on the other hand, permits the detection of nuclear proteins (modified histones, histone variants and modifiers, transcription machinery and factors, nuclear sub-compartments, etc). The major challenge in combining immunofluorescence and 3D DNA FISH is, on the one hand to preserve the epitope detected by the antibody as well as the 3D architecture of the nucleus, and on the other hand, to allow the penetration of the DNA probe to detect gene loci or chromosome territories (1-5). Here we provide a protocol that combines visualization of chromatin modifications with genomic loci in 3D preserved nuclei.
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Affiliation(s)
- Julie Chaumeil
- Department of Pathology, New York University School of Medicine, NY, USA
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33
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Rubtsov NB. Organization of eukaryotic chromosomes: From Kol’tsov’s studies up to present day. RUSS J GENET+ 2013. [DOI: 10.1134/s1022795413010109] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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34
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Yang CX, Liu Z, Fleurot R, Adenot P, Duranthon V, Vignon X, Zhou Q, Renard JP, Beaujean N. Heterochromatin reprogramming in rabbit embryos after fertilization, intra-, and inter-species SCNT correlates with preimplantation development. Reproduction 2013; 145:149-59. [PMID: 23221012 DOI: 10.1530/rep-11-0421] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
To investigate the embryonic genome organization upon fertilization and somatic cell nuclear transfer (SCNT), we tracked HP1β and CENP, two well-characterized protein markers of pericentric and centromeric compartments respectively, in four types of embryos produced by rabbit in vivo fertilization, rabbit parthenogenesis, rabbit-to-rabbit, and bovine-to-rabbit SCNT. In the interphase nuclei of rabbit cultured fibroblasts, centromeres and associated pericentric heterochromatin are usually isolated. Clustering into higher-order chromatin structures, such as the chromocenters seen in mouse and bovine somatic cells, could not be observed in rabbit fibroblasts. After fertilization, centromeres and associated pericentric heterochromatin are quite dispersed in rabbit embryos. The somatic-like organization is progressively established and completed only by the 8/16-cell stage, a stage that corresponds to major embryonic genome activation in this species. In SCNT embryos, pericentric heterochromatin distribution typical for rabbit and bovine somatic cells was incompletely reverted into the 1-cell embryonic form with remnants of heterochromatin clusters in 100% of bovine-to-rabbit embryos. Subsequently, the donor cell nuclear organization was rapidly re-established by the 4-cell stage. Remarkably, the incomplete remodeling of bovine-to-rabbit 1-cell embryos was associated with delayed transcriptional activation compared with rabbit-to-rabbit embryos. Together, the results confirm that pericentric heterochromatin spatio-temporal reorganization is an important step of embryonic genome reprogramming. It also appears that genome reorganization in SCNT embryos is mainly dependent on the nuclear characteristics of the donor cells, not on the recipient cytoplasm.
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Affiliation(s)
- Cai-Xia Yang
- INRA, UMR 1198 Biologie du Developpement et Reproduction, F-78350 Jouy en Josas, France
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Hakim O, Sung MH, Nakayamada S, Voss TC, Baek S, Hager GL. Spatial congregation of STAT binding directs selective nuclear architecture during T-cell functional differentiation. Genome Res 2012; 23:462-72. [PMID: 23212947 PMCID: PMC3589535 DOI: 10.1101/gr.147652.112] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Higher-order genome organization shows tissue-specific patterns. However, functional relevance and the mechanisms shaping the genome architecture are poorly understood. Here we report a profound shift from promiscuous to highly selective genome organization that accompanies the effector lineage choice of differentiating T cells. As multipotent naive cells receive antigenic signals and commit to a T helper (Th) pathway, the genome-wide contacts of a lineage-specific cytokine locus are preferentially enriched for functionally relevant genes. Despite the establishment of divergent interactomes and global reprogramming of transcription in Th1 versus Th2, the overall expression status of the contact genes is surprisingly similar between the two lineages. Importantly, during differentiation, the genomic contacts are retained and strengthened precisely at DNA binding sites of the specific lineage-determining STAT transcription factor. In cells from the specific STAT knock-out mouse, the signature cytokine locus is unable to shed the promiscuous contacts established in the naive T cells, indicating the importance of genomic STAT binding. Altogether, the global aggregation of STAT binding loci from genic and nongenic regions highlights a new role for differentiation-promoting transcription factors in direct specification of higher-order nuclear architecture through interacting with regulatory regions. Such subnuclear environments have significant implications for efficient functioning of the mature effector lymphocytes.
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Affiliation(s)
- Ofir Hakim
- Laboratory of Receptor Biology and Gene Expression, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA.
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36
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Holwerda S, de Laat W. Chromatin loops, gene positioning, and gene expression. Front Genet 2012; 3:217. [PMID: 23087710 PMCID: PMC3473233 DOI: 10.3389/fgene.2012.00217] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2012] [Accepted: 10/01/2012] [Indexed: 01/09/2023] Open
Abstract
Technological developments and intense research over the last years have led to a better understanding of the 3D structure of the genome and its influence on genome function inside the cell nucleus. We will summarize topological studies performed on four model gene loci: the α- and β-globin gene loci, the antigen receptor loci, the imprinted H19-Igf2 locus and the Hox gene clusters. Collectively, these studies show that regulatory DNA sequences physically contact genes to control their transcription. Proteins set up the 3D configuration of the genome and we will discuss the roles of the key structural organizers CTCF and cohesin, the nuclear lamina and the transcription machinery. Finally, genes adopt non-random positions in the nuclear interior. We will review studies on gene positioning and propose that cell-specific genome conformations can juxtapose a regulatory sequence on one chromosome to a responsive gene on another chromosome to cause altered gene expression in subpopulations of cells.
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Affiliation(s)
- Sjoerd Holwerda
- Hubrecht Institute, Royal Netherlands Academy of Arts and Sciences, University Medical Center Utrecht Utrecht, Netherlands
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37
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Global changes in the nuclear positioning of genes and intra- and interdomain genomic interactions that orchestrate B cell fate. Nat Immunol 2012; 13:1196-204. [PMID: 23064439 PMCID: PMC3501570 DOI: 10.1038/ni.2432] [Citation(s) in RCA: 217] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2012] [Accepted: 08/27/2012] [Indexed: 12/14/2022]
Abstract
The genome is folded into domains located in either transcriptionally inert or permissive compartments. Here we used genome-wide strategies to characterize domains during B cell development. Structured Interaction Matrix Analysis revealed that CTCF occupancy was primarily associated with intra-domain interactions, whereas p300, E2A and PU.1 bound sites were associated with intra- and inter-domain interactions that are developmentally regulated. We identified a spectrum of genes that switched nuclear location during early B cell development. In progenitors the transcriptionally inactive Ebf1 locus was sequestered at the nuclear lamina, thereby preserving multipotency. Upon development into the pro-B cell stage Ebf1 and other genes switched compartments to establish de novo intra- and inter-domain interactions that are associated with a B lineage specific transcription signature.
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Gross S, Catez F, Masumoto H, Lomonte P. Centromere architecture breakdown induced by the viral E3 ubiquitin ligase ICP0 protein of herpes simplex virus type 1. PLoS One 2012; 7:e44227. [PMID: 23028505 PMCID: PMC3447814 DOI: 10.1371/journal.pone.0044227] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2012] [Accepted: 07/30/2012] [Indexed: 01/20/2023] Open
Abstract
The viral E3 ubiquitin ligase ICP0 protein has the unique property to temporarily localize at interphase and mitotic centromeres early after infection of cells by the herpes simplex virus type 1 (HSV-1). As a consequence ICP0 induces the proteasomal degradation of several centromeric proteins (CENPs), namely CENP-A, the centromeric histone H3 variant, CENP-B and CENP-C. Following ICP0-induced centromere modification cells trigger a specific response to centromeres called interphase Centromere Damage Response (iCDR). The biological significance of the iCDR is unknown; so is the degree of centromere structural damage induced by ICP0. Interphase centromeres are complex structures made of proximal and distal protein layers closely associated to CENP-A-containing centromeric chromatin. Using several cell lines constitutively expressing GFP-tagged CENPs, we investigated the extent of the centromere destabilization induced by ICP0. We show that ICP0 provokes the disappearance from centromeres, and the proteasomal degradation of several CENPs from the NAC (CENP-A nucleosome associated) and CAD (CENP-A Distal) complexes. We then investigated the nucleosomal occupancy of the centromeric chromatin in ICP0-expressing cells by micrococcal nuclease (MNase) digestion analysis. ICP0 expression either following infection or in cell lines constitutively expressing ICP0 provokes significant modifications of the centromeric chromatin structure resulting in higher MNase accessibility. Finally, using human artificial chromosomes (HACs), we established that ICP0-induced iCDR could also target exogenous centromeres. These results demonstrate that, in addition to the protein complexes, ICP0 also destabilizes the centromeric chromatin resulting in the complete breakdown of the centromere architecture, which consequently induces iCDR.
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Affiliation(s)
- Sylvain Gross
- Virus and Centromere Team, Centre de Génétique et de Physiologie Moléculaire et Cellulaire CNRS, UMR5534, Villeurbanne, France
- Université de Lyon 1, Lyon, France
- Laboratoire d'excellence, Labex DEVweCAN, Lyon, France
| | - Frédéric Catez
- Virus and Centromere Team, Centre de Génétique et de Physiologie Moléculaire et Cellulaire CNRS, UMR5534, Villeurbanne, France
- Université de Lyon 1, Lyon, France
| | - Hiroshi Masumoto
- Laboratory of Cell Engineering, Kazusa DNA Research Institute, Chiba, Japan
| | - Patrick Lomonte
- Virus and Centromere Team, Centre de Génétique et de Physiologie Moléculaire et Cellulaire CNRS, UMR5534, Villeurbanne, France
- Université de Lyon 1, Lyon, France
- Laboratoire d'excellence, Labex DEVweCAN, Lyon, France
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HSV-1 genome subnuclear positioning and associations with host-cell PML-NBs and centromeres regulate LAT locus transcription during latency in neurons. PLoS Pathog 2012; 8:e1002852. [PMID: 22912575 PMCID: PMC3415458 DOI: 10.1371/journal.ppat.1002852] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2012] [Accepted: 06/26/2012] [Indexed: 02/04/2023] Open
Abstract
Major human pathologies are caused by nuclear replicative viruses establishing life-long latent infection in their host. During latency the genomes of these viruses are intimately interacting with the cell nucleus environment. A hallmark of herpes simplex virus type 1 (HSV-1) latency establishment is the shutdown of lytic genes expression and the concomitant induction of the latency associated (LAT) transcripts. Although the setting up and the maintenance of the latent genetic program is most likely dependent on a subtle interplay between viral and nuclear factors, this remains uninvestigated. Combining the use of in situ fluorescent-based approaches and high-resolution microscopic analysis, we show that HSV-1 genomes adopt specific nuclear patterns in sensory neurons of latently infected mice (28 days post-inoculation, d.p.i.). Latent HSV-1 genomes display two major patterns, called “Single” and “Multiple”, which associate with centromeres, and with promyelocytic leukemia nuclear bodies (PML-NBs) as viral DNA-containing PML-NBs (DCP-NBs). 3D-image reconstruction of DCP-NBs shows that PML forms a shell around viral genomes and associated Daxx and ATRX, two PML partners within PML-NBs. During latency establishment (6 d.p.i.), infected mouse TGs display, at the level of the whole TG and in individual cells, a substantial increase of PML amount consistent with the interferon-mediated antiviral role of PML. “Single” and “Multiple” patterns are reminiscent of low and high-viral genome copy-containing neurons. We show that LAT expression is significantly favored within the “Multiple” pattern, which underlines a heterogeneity of LAT expression dependent on the viral genome copy number, pattern acquisition, and association with nuclear domains. Infection of PML-knockout mice demonstrates that PML/PML-NBs are involved in virus nuclear pattern acquisition, and negatively regulate the expression of the LAT. This study demonstrates that nuclear domains including PML-NBs and centromeres are functionally involved in the control of HSV-1 latency, and represent a key level of host/virus interaction. After an initial lytic infection, many viruses establish a lifelong latent infection that hides them from the host immune system activity until reactivation. To understand the resurgence of the associated diseases, it is indispensable to acquire a better knowledge of the different mechanisms involved in the antiviral defense. During latency, viral genomes of nuclear-replicative viruses, such as herpes simplex virus type 1 (HSV-1), are stored in the nucleus of host cells in a non-integrated form. Latency establishment is associated with a drastic change in HSV-1 gene expression program that is maintained until reactivation occurs. The last two decades of research has revealed that the functional organization of the cell nucleus, so-called nuclear architecture, is a major factor of regulation of cellular genes expression. Nonetheless, the role of nuclear architecture on HSV-1 gene expression has been widely overlooked. Here we describe that the genome of HSV-1 selectively interacts with two major nuclear structures, the promyelocytic nuclear bodies (PMLNBs or ND10) and the centromeres. We provide evidence supporting that these nuclear domains directly influence the behavior of latent viral genomes and their transcriptional activity. Overall, this study demonstrates that nuclear architecture is a major parameter driving the highly complex HSV-1 latency process.
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Brandt VL, Hewitt SL, Skok JA. It takes two: communication between homologous alleles preserves genomic stability during V(D)J recombination. Nucleus 2012; 1:23-9. [PMID: 21327101 DOI: 10.4161/nucl.1.1.10595] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2009] [Accepted: 11/11/2009] [Indexed: 01/14/2023] Open
Abstract
Chromosome pairing is involved in X chromosome inactivation, a classic instance of monoallelic gene expression. Antigen receptor genes are also monoallelically expressed ("allelically excluded") by B and T lymphocytes, and we asked whether pairing contributed to the regulation of V(D)J recombination at these loci. We found that homologous immunoglobulin (Ig) alleles pair up during recombination. Homologous Ig pairing is substantially reduced in the absence of the RAG1/RAG2 recombinase, but a transgene expressing an active site RAG1 mutant (which binds but does not cleave DNA) rescues pairing in Rag1(-/-) developing B cells. RAG-mediated cleavage on one allele induces the other allele to relocate to pericentromeric heterochromatin (PCH), likely to ensure that only one allele is cut at a time. This relocation to PCH requires the DNA damage sensor ATM (ataxia telengiectasia mutated). In the absence of ATM, repositioning at PCH is diminished and the incidence of cleavage on both alleles is significantly increased. ATM appears to be activated by the introduction of a double-strand break on one allele to act in trans on the uncleaved allele, repositioning or maintaining it at PCH, to prevent bi-allelic recombination and chromosomal translocations.
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Affiliation(s)
- Vicky L Brandt
- Department of Pathology, New York University School of Medicine, New York, NY, USA
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41
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Johnson K, Chaumeil J, Micsinai M, Wang JMH, Ramsey LB, Baracho GV, Rickert RC, Strino F, Kluger Y, Farrar MA, Skok JA. IL-7 functionally segregates the pro-B cell stage by regulating transcription of recombination mediators across cell cycle. THE JOURNAL OF IMMUNOLOGY 2012; 188:6084-92. [PMID: 22581861 DOI: 10.4049/jimmunol.1200368] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Ag receptor diversity involves the introduction of DNA double-stranded breaks during lymphocyte development. To ensure fidelity, cleavage is confined to the G(0)-G(1) phase of the cell cycle. One established mechanism of regulation is through periodic degradation of the RAG2 recombinase protein. However, there are additional levels of protection. In this paper, we show that cyclical changes in the IL-7R signaling pathway functionally segregate pro-B cells according to cell cycle status. In consequence, the level of a downstream effector of IL-7 signaling, phospho-STAT5, is inversely correlated with cell cycle expression of Rag, a key gene involved in recombination. Higher levels of phopho-STAT5 in S-G(2) correlate with decreased Rag expression and Rag relocalization to pericentromeric heterochromatin. These cyclical changes in transcription and locus repositioning are ablated upon transformation with v-Abl, which renders STAT5 constitutively active across the cell cycle. We propose that this activity of the IL-7R/STAT5 pathway plays a critical protective role in development, complementing regulation of RAG2 at the protein level, to ensure that recombination does not occur during replication. Our data, suggesting that pro-B cells are not a single homogeneous population, explain inconsistencies in the role of IL-7 signaling in regulating Igh recombination.
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Affiliation(s)
- Kristen Johnson
- Department of Pathology, New York University School of Medicine, New York, NY 10016, USA
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42
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Hakim O, Resch W, Yamane A, Klein I, Kieffer-Kwon KR, Jankovic M, Oliveira T, Bothmer A, Voss TC, Ansarah-Sobrinho C, Mathe E, Liang G, Cobell J, Nakahashi H, Robbiani DF, Nussenzweig A, Hager GL, Nussenzweig MC, Casellas R. DNA damage defines sites of recurrent chromosomal translocations in B lymphocytes. Nature 2012; 484:69-74. [PMID: 22314321 DOI: 10.1038/nature10909] [Citation(s) in RCA: 168] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2011] [Accepted: 01/31/2012] [Indexed: 01/07/2023]
Abstract
Recurrent chromosomal translocations underlie both haematopoietic and solid tumours. Their origin has been ascribed to selection of random rearrangements, targeted DNA damage, or frequent nuclear interactions between translocation partners; however, the relative contribution of each of these elements has not been measured directly or on a large scale. Here we examine the role of nuclear architecture and frequency of DNA damage in the genesis of chromosomal translocations by measuring these parameters simultaneously in cultured mouse B lymphocytes. In the absence of recurrent DNA damage, translocations between Igh or Myc and all other genes are directly related to their contact frequency. Conversely, translocations associated with recurrent site-directed DNA damage are proportional to the rate of DNA break formation, as measured by replication protein A accumulation at the site of damage. Thus, non-targeted rearrangements reflect nuclear organization whereas DNA break formation governs the location and frequency of recurrent translocations, including those driving B-cell malignancies.
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Affiliation(s)
- Ofir Hakim
- Laboratory of Receptor Biology and Gene Expression, NCI, National Institutes of Health, Bethesda, Maryland 20892, USA
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43
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Volz J, Bártfai R, Petter M, Langer C, Josling G, Tsuboi T, Schwach F, Baum J, Rayner J, Stunnenberg H, Duffy M, Cowman A. PfSET10, a Plasmodium falciparum Methyltransferase, Maintains the Active var Gene in a Poised State during Parasite Division. Cell Host Microbe 2012; 11:7-18. [DOI: 10.1016/j.chom.2011.11.011] [Citation(s) in RCA: 104] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2011] [Revised: 10/27/2011] [Accepted: 11/30/2011] [Indexed: 11/25/2022]
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44
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Chason RJ, Csokmay J, Segars JH, DeCherney AH, Armant DR. Environmental and epigenetic effects upon preimplantation embryo metabolism and development. Trends Endocrinol Metab 2011; 22:412-20. [PMID: 21741268 PMCID: PMC3183171 DOI: 10.1016/j.tem.2011.05.005] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/05/2011] [Revised: 05/10/2011] [Accepted: 05/25/2011] [Indexed: 12/20/2022]
Abstract
In vitro fertilization has provided a unique window into the metabolic processes that drive embryonic growth and development from a fertilized ovum to a competent blastocyst. Post-fertilization development is dependent upon a dramatic reshuffling of the parental genomes during meiosis, as well as epigenetic changes that provide a new and autonomous set of instructions to guide cellular differentiation both in the embryo and beyond. Although early literature focused simply on the substrates and culture conditions required for progress through embryonic development, more recent insights lead us to suggest that the surrounding environment can alter the epigenome, which can, in turn, impact upon embryonic metabolism and developmental competence.
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Affiliation(s)
- Rebecca J Chason
- Program in Reproductive and Adult Endocrinology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
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45
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Dai Z, Dai X. Nuclear colocalization of transcription factor target genes strengthens coregulation in yeast. Nucleic Acids Res 2011; 40:27-36. [PMID: 21880591 PMCID: PMC3245921 DOI: 10.1093/nar/gkr689] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Eukaryotic chromosomes are not randomly distributed in the interphase nucleus, but instead occupy distinct territories. Nonetheless, the genome-wide relationships of gene regulation to gene nuclear location remain poorly understood in yeast. In the three-dimensional view of gene regulation, we found that a considerable number of transcription factors (TFs) regulate genes that are colocalized in the nucleus. Colocalized TF target genes are more strongly coregulated compared with the other TF target genes. Target genes of chromatin regulators are also colocalized. These results demonstrate that colocalization of coregulated genes is a common process, and three-dimensional gene positioning is an important part of gene regulation. Our findings will have implications in understanding nuclear architecture and function.
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Affiliation(s)
- Zhiming Dai
- Department of Electronics, School of Information Science and Technology, Sun Yat-Sen University, Guangzhou 510006, China
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46
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Collins A, Hewitt S, Chaumeil J, Sellars M, Micsinai M, Allinne J, Parisi F, Nora EP, Bolland D, Corcoran A, Kluger Y, Bosselut R, Ellmeier W, Chong M, Littman D, Skok J. RUNX transcription factor-mediated association of Cd4 and Cd8 enables coordinate gene regulation. Immunity 2011; 34:303-14. [PMID: 21435585 PMCID: PMC3101577 DOI: 10.1016/j.immuni.2011.03.004] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2010] [Revised: 09/07/2010] [Accepted: 12/21/2010] [Indexed: 01/24/2023]
Abstract
T cell fate is associated with mutually exclusive expression of CD4 or CD8 in helper and cytotoxic T cells, respectively. How expression of one locus is temporally coordinated with repression of the other has been a long-standing enigma, though we know RUNX transcription factors activate the Cd8 locus, silence the Cd4 locus, and repress the Zbtb7b locus (encoding the transcription factor ThPOK), which is required for CD4 expression. Here we found that nuclear organization was altered by interplay among members of this transcription factor circuitry: RUNX binding mediated association of Cd4 and Cd8 whereas ThPOK binding kept the loci apart. Moreover, targeted deletions within Cd4 modulated CD8 expression and pericentromeric repositioning of Cd8. Communication between Cd4 and Cd8 thus appears to enable long-range epigenetic regulation to ensure that expression of one excludes the other in mature CD4 or CD8 single-positive (SP) cells.
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Affiliation(s)
- Amélie Collins
- Molecular Pathogenesis Program, The Kimmel Center for Biology and Medicine of the Skirball Institute, New York University School of Medicine, 550 First Avenue, New York, NY 10016, USA
| | - Susannah L. Hewitt
- Department of Pathology, New York University School of Medicine, 550 First Avenue, New York, NY 10016, USA
| | - Julie Chaumeil
- Department of Pathology, New York University School of Medicine, 550 First Avenue, New York, NY 10016, USA
| | - MacLean Sellars
- Molecular Pathogenesis Program, The Kimmel Center for Biology and Medicine of the Skirball Institute, New York University School of Medicine, 550 First Avenue, New York, NY 10016, USA
| | - Mariann Micsinai
- New York University Center for Health Informatics and Bioinformatics, New York University School of Medicine, 550 First Avenue, New York, NY 10016, USA
- NYU Cancer Institute, New York University School of Medicine, 550 First Avenue, New York, NY 10016, USA
- Department of Pathology and Yale Cancer Center, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA
| | - Jeanne Allinne
- Department of Pathology, New York University School of Medicine, 550 First Avenue, New York, NY 10016, USA
| | - Fabio Parisi
- Department of Pathology and Yale Cancer Center, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA
| | - Elphège P. Nora
- Institut Curie, CNRS UMR3215, INSERM U934, 75724 Paris Cedex 05, France
| | - Dan J. Bolland
- The Babraham Institute, Babraham Research Campus, Cambridge, CB22 3AT, UK
| | - Anne E. Corcoran
- The Babraham Institute, Babraham Research Campus, Cambridge, CB22 3AT, UK
| | - Yuval Kluger
- Department of Pathology and Yale Cancer Center, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA
| | - Remy Bosselut
- Laboratory of Immune Cell Biology, Center for Cancer Research (CCR), NCI, NIH, Bethesda, MD 20892-4259, USA
| | - Wilfried Ellmeier
- Division of Immunobiology, Institute of Immunology, Medical University of Vienna, Lazarettgasse 19, A-1090 Vienna, Austria
| | - Mark M.W. Chong
- Molecular Pathogenesis Program, The Kimmel Center for Biology and Medicine of the Skirball Institute, New York University School of Medicine, 550 First Avenue, New York, NY 10016, USA
| | - Dan R. Littman
- Molecular Pathogenesis Program, The Kimmel Center for Biology and Medicine of the Skirball Institute, New York University School of Medicine, 550 First Avenue, New York, NY 10016, USA
- Howard Hughes Medical Institute
| | - Jane A. Skok
- Department of Pathology, New York University School of Medicine, 550 First Avenue, New York, NY 10016, USA
- Division of Infection and Immunity, The Department of Immunology and Molecular Pathology, University College London, London W1T 4JF, UK
- Corresponding author
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47
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Herpesviral replication compartments move and coalesce at nuclear speckles to enhance export of viral late mRNA. Proc Natl Acad Sci U S A 2011; 108:E136-44. [PMID: 21555562 DOI: 10.1073/pnas.1103411108] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The role of the intranuclear movement of chromatin in gene expression is not well-understood. Herpes simplex virus forms replication compartments (RCs) in infected cell nuclei as sites of viral DNA replication and late gene transcription. These structures develop from small compartments that grow in size, move, and coalesce. Quantitative analysis of RC trajectories, derived from 4D images, shows that most RCs move by directed motion. Directed movement is impaired in the presence of actin and myosin inhibitors as well as a transcription inhibitor. In addition, RCs coalesce at and reorganize nuclear speckles. Lastly, distinct effects of actin and myosin inhibitors on viral gene expression suggest that RC movement is not required for transcription, but rather, movement results in the bridging of transcriptionally active RCs with nuclear speckles to form structures that enhance export of viral late mRNAs.
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48
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Acquistapace A, Bru T, Lesault PF, Figeac F, Coudert AE, Le Coz O, Christov C, Baudin X, Auber F, Yiou R, Dubois-Randé JL, Rodriguez AM. Human mesenchymal stem cells reprogram adult cardiomyocytes toward a progenitor-like state through partial cell fusion and mitochondria transfer. Stem Cells 2011; 29:812-24. [PMID: 21433223 PMCID: PMC3346716 DOI: 10.1002/stem.632] [Citation(s) in RCA: 192] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Because stem cells are often found to improve repair tissue including heart without evidence of engraftment or differentiation, mechanisms underlying wound healing are still elusive. Several studies have reported that stem cells can fuse with cardiomyocytes either by permanent or partial cell fusion processes. However, the respective physiological impact of these two processes remains unknown in part because of the lack of knowledge of the resulting hybrid cells. To further characterize cell fusion, we cocultured mouse fully differentiated cardiomyocytes with human multipotent adipose-derived stem (hMADS) cells as a model of adult stem cells. We found that heterologous cell fusion promoted cardiomyocyte reprogramming back to a progenitor-like state. The resulting hybrid cells expressed early cardiac commitment and proliferation markers such as GATA-4, myocyte enhancer factor 2C, Nkx2.5, and Ki67 and exhibited a mouse genotype. Interestingly, human bone marrow-derived stem cells shared similar reprogramming properties than hMADS cells but not human fibroblasts, which suggests that these features might be common to multipotent cells. Furthermore, cardiac hybrid cells were preferentially generated by partial rather than permanent cell fusion and that intercellular structures composed of f-actin and microtubule filaments were involved in the process. Finally, we showed that stem cell mitochondria were transferred into cardiomyocytes, persisted in hybrids and were required for somatic cell reprogramming. In conclusion, by providing new insights into previously reported cell fusion processes, our data might contribute to a better understanding of stem cell-mediated regenerative mechanisms and thus, the development of more efficient stem cell-based heart therapies.
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Affiliation(s)
- Adrien Acquistapace
- Institut Mondor de Recherche Biomédicale
INSERM : U955Université Paris XII Val de MarneIFR1094010 Créteil, FR
| | - Thierry Bru
- Institut Mondor de Recherche Biomédicale
INSERM : U955Université Paris XII Val de MarneIFR1094010 Créteil, FR
| | - Pierre-François Lesault
- Institut Mondor de Recherche Biomédicale
INSERM : U955Université Paris XII Val de MarneIFR1094010 Créteil, FR
| | - Florence Figeac
- Institut Mondor de Recherche Biomédicale
INSERM : U955Université Paris XII Val de MarneIFR1094010 Créteil, FR
| | - Amélie E. Coudert
- Institut Mondor de Recherche Biomédicale
INSERM : U955Université Paris XII Val de MarneIFR1094010 Créteil, FR
| | - Olivier Le Coz
- Institut Mondor de Recherche Biomédicale
INSERM : U955Université Paris XII Val de MarneIFR1094010 Créteil, FR
| | - Christo Christov
- Institut Mondor de Recherche Biomédicale
INSERM : U955Université Paris XII Val de MarneIFR1094010 Créteil, FR
| | - Xavier Baudin
- IJM, Institut Jacques Monod
CNRS : UMR7592Université Paris Diderot - Paris 7Batiment Buffon 15 rue Hélène Brion 75205 Paris cédex 13,FR
| | - Fréderic Auber
- Service de chirurgie pédiatrique viscérale et néonatale
Assistance publique - Hôpitaux de Paris (AP-HP)Hôpital Armand Trousseau75012 Paris,FR
| | - René Yiou
- Institut Mondor de Recherche Biomédicale
INSERM : U955Université Paris XII Val de MarneIFR1094010 Créteil, FR
| | - Jean-Luc Dubois-Randé
- Institut Mondor de Recherche Biomédicale
INSERM : U955Université Paris XII Val de MarneIFR1094010 Créteil, FR
| | - Anne-Marie Rodriguez
- Institut Mondor de Recherche Biomédicale
INSERM : U955Université Paris XII Val de MarneIFR1094010 Créteil, FR
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49
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Patra SK, Deb M, Patra A. Molecular marks for epigenetic identification of developmental and cancer stem cells. Clin Epigenetics 2011; 2:27-53. [PMID: 22704268 PMCID: PMC3365374 DOI: 10.1007/s13148-010-0016-0] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2010] [Accepted: 11/24/2010] [Indexed: 12/18/2022] Open
Abstract
UNLABELLED Epigenetic regulations of genes by reversible methylation of DNA (at the carbon-5 of cytosine) and numerous reversible modifications of histones play important roles in normal physiology and development, and epigenetic deregulations are associated with developmental disorders and various disease states, including cancer. Stem cells have the capacity to self-renew indefinitely. Similar to stem cells, some malignant cells have the capacity to divide indefinitely and are referred to as cancer stem cells. In recent times, direct correlation between epigenetic modifications and reprogramming of stem cell and cancer stem cell is emerging. Major discoveries were made with investigations on reprogramming gene products, also known as master regulators of totipotency and inducer of pluoripotency, namely, OCT4, NANOG, cMYC, SOX2, Klf4, and LIN28. The challenge to induce pluripotency is the insertion of four reprogramming genes (Oct4, Sox2, Klf4, and c-Myc) into the genome. There are always risks of silencing of these genes by epigenetic modifications in the host cells, particularly, when introduced through retroviral techniques. In this contribution, we will discuss some of the major discoveries on epigenetic modifications within the chromatin of various genes associated with cancer progression and cancer stem cells in comparison to normal development of stem cell. These modifications may be considered as molecular signatures for predicting disorders of development and for identifying disease states. ELECTRONIC SUPPLEMENTARY MATERIAL The online version of this article (doi:10.1007/s13148-010-0016-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Samir Kumar Patra
- Epigenetics and Cancer Research Laboratory, Department of Life Science, National Institute of Technology, Rourkela, Orissa 769008 India
| | - Moonmoon Deb
- Epigenetics and Cancer Research Laboratory, Department of Life Science, National Institute of Technology, Rourkela, Orissa 769008 India
| | - Aditi Patra
- Department of Animal Science, Bidhan Chandra Krishi Viswavidyalaya, Mohanpur, Nadia, West Bengal India
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50
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Georgiev P, Chlamydas S, Akhtar A. Drosophila dosage compensation: males are from Mars, females are from Venus. Fly (Austin) 2011; 5:147-54. [PMID: 21339706 DOI: 10.4161/fly.5.2.14934] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Dosage compensation of X-linked genes is a phenomenon of concerted, chromosome-wide regulation of gene expression underpinned by sustained and tightly regulated histone modifications and chromatin remodeling, coupled with constrains of nuclear architecture. This elaborate process allows the accomplishment of regulated expression of genes on the single male X chromosome to levels comparable to those expressed from the two X chromosomes in females. The ribonucleoprotein Male Specific Lethal (MSL) complex is enriched on the male X chromosome and is intricately involved in this process in Drosophila melanogaster. In this review we discuss the recent advances that highlight the complexity lying behind regulation of gene expression by just two-fold.
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Affiliation(s)
- Plamen Georgiev
- Max Planck Institute of Immunobiology and Epigenetics, Freiburg, Germany
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