1
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Cecalev D, Viçoso B, Galupa R. Compensation of gene dosage on the mammalian X. Development 2024; 151:dev202891. [PMID: 39140247 PMCID: PMC11361640 DOI: 10.1242/dev.202891] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/15/2024]
Abstract
Changes in gene dosage can have tremendous evolutionary potential (e.g. whole-genome duplications), but without compensatory mechanisms, they can also lead to gene dysregulation and pathologies. Sex chromosomes are a paradigmatic example of naturally occurring gene dosage differences and their compensation. In species with chromosome-based sex determination, individuals within the same population necessarily show 'natural' differences in gene dosage for the sex chromosomes. In this Review, we focus on the mammalian X chromosome and discuss recent new insights into the dosage-compensation mechanisms that evolved along with the emergence of sex chromosomes, namely X-inactivation and X-upregulation. We also discuss the evolution of the genetic loci and molecular players involved, as well as the regulatory diversity and potentially different requirements for dosage compensation across mammalian species.
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Affiliation(s)
- Daniela Cecalev
- Molecular, Cellular and Developmental Biology (MCD) Unit, Centre de Biologie Intégrative (CBI), University of Toulouse, CNRS, UPS, 31062, Toulouse, France
| | - Beatriz Viçoso
- Institute of Science and Technology Austria (ISTA), Am Campus 1, Klosterneuburg 3400, Austria
| | - Rafael Galupa
- Molecular, Cellular and Developmental Biology (MCD) Unit, Centre de Biologie Intégrative (CBI), University of Toulouse, CNRS, UPS, 31062, Toulouse, France
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2
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Ferrer J, Dimitrova N. Transcription regulation by long non-coding RNAs: mechanisms and disease relevance. Nat Rev Mol Cell Biol 2024; 25:396-415. [PMID: 38242953 PMCID: PMC11045326 DOI: 10.1038/s41580-023-00694-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/11/2023] [Indexed: 01/21/2024]
Abstract
Long non-coding RNAs (lncRNAs) outnumber protein-coding transcripts, but their functions remain largely unknown. In this Review, we discuss the emerging roles of lncRNAs in the control of gene transcription. Some of the best characterized lncRNAs have essential transcription cis-regulatory functions that cannot be easily accomplished by DNA-interacting transcription factors, such as XIST, which controls X-chromosome inactivation, or imprinted lncRNAs that direct allele-specific repression. A growing number of lncRNA transcription units, including CHASERR, PVT1 and HASTER (also known as HNF1A-AS1) act as transcription-stabilizing elements that fine-tune the activity of dosage-sensitive genes that encode transcription factors. Genetic experiments have shown that defects in such transcription stabilizers often cause severe phenotypes. Other lncRNAs, such as lincRNA-p21 (also known as Trp53cor1) and Maenli (Gm29348) contribute to local activation of gene transcription, whereas distinct lncRNAs influence gene transcription in trans. We discuss findings of lncRNAs that elicit a function through either activation of their transcription, transcript elongation and processing or the lncRNA molecule itself. We also discuss emerging evidence of lncRNA involvement in human diseases, and their potential as therapeutic targets.
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Affiliation(s)
- Jorge Ferrer
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology (BIST), Barcelona, Spain.
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Madrid, Spain.
- Department of Metabolism, Digestion and Reproduction, Imperial College London, London, UK.
| | - Nadya Dimitrova
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT, USA.
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3
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Malcore RM, Kalantry S. A Comparative Analysis of Mouse Imprinted and Random X-Chromosome Inactivation. EPIGENOMES 2024; 8:8. [PMID: 38390899 PMCID: PMC10885068 DOI: 10.3390/epigenomes8010008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2024] [Revised: 02/01/2024] [Accepted: 02/06/2024] [Indexed: 02/24/2024] Open
Abstract
The mammalian sexes are distinguished by the X and Y chromosomes. Whereas males harbor one X and one Y chromosome, females harbor two X chromosomes. To equalize X-linked gene expression between the sexes, therian mammals have evolved X-chromosome inactivation as a dosage compensation mechanism. During X-inactivation, most genes on one of the two X chromosomes in females are transcriptionally silenced, thus equalizing X-linked gene expression between the sexes. Two forms of X-inactivation characterize eutherian mammals, imprinted and random. Imprinted X-inactivation is defined by the exclusive inactivation of the paternal X chromosome in all cells, whereas random X-inactivation results in the silencing of genes on either the paternal or maternal X chromosome in individual cells. Both forms of X-inactivation have been studied intensively in the mouse model system, which undergoes both imprinted and random X-inactivation early in embryonic development. Stable imprinted and random X-inactivation requires the induction of the Xist long non-coding RNA. Following its induction, Xist RNA recruits proteins and complexes that silence genes on the inactive-X. In this review, we present a current understanding of the mechanisms of Xist RNA induction, and, separately, the establishment and maintenance of gene silencing on the inactive-X by Xist RNA during imprinted and random X-inactivation.
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Affiliation(s)
| | - Sundeep Kalantry
- Department of Human Genetics, University of Michigan Medical School, Ann Arbor, MI 48105, USA
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4
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Luchsinger-Morcelle SJ, Gribnau J, Mira-Bontenbal H. Orchestrating Asymmetric Expression: Mechanisms behind Xist Regulation. EPIGENOMES 2024; 8:6. [PMID: 38390897 PMCID: PMC10885031 DOI: 10.3390/epigenomes8010006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Revised: 01/19/2024] [Accepted: 01/22/2024] [Indexed: 02/24/2024] Open
Abstract
Compensation for the gene dosage disequilibrium between sex chromosomes in mammals is achieved in female cells by repressing one of its X chromosomes through a process called X chromosome inactivation (XCI), exemplifying the control of gene expression by epigenetic mechanisms. A critical player in this mechanism is Xist, a long, non-coding RNA upregulated from a single X chromosome during early embryonic development in female cells. Over the past few decades, many factors involved at different levels in the regulation of Xist have been discovered. In this review, we hierarchically describe and analyze the different layers of Xist regulation operating concurrently and intricately interacting with each other to achieve asymmetric and monoallelic upregulation of Xist in murine female cells. We categorize these into five different classes: DNA elements, transcription factors, other regulatory proteins, long non-coding RNAs, and the chromatin and topological landscape surrounding Xist.
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Affiliation(s)
| | - Joost Gribnau
- Department of Developmental Biology, Erasmus MC, University Medical Center, 3015 GD Rotterdam, The Netherlands
| | - Hegias Mira-Bontenbal
- Department of Developmental Biology, Erasmus MC, University Medical Center, 3015 GD Rotterdam, The Netherlands
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5
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Schwämmle T, Schulz EG. Regulatory principles and mechanisms governing the onset of random X-chromosome inactivation. Curr Opin Genet Dev 2023; 81:102063. [PMID: 37356341 PMCID: PMC10465972 DOI: 10.1016/j.gde.2023.102063] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Revised: 05/23/2023] [Accepted: 05/24/2023] [Indexed: 06/27/2023]
Abstract
X-chromosome inactivation (XCI) has evolved in mammals to compensate for the difference in X-chromosomal dosage between the sexes. In placental mammals, XCI is initiated during early embryonic development through upregulation of the long noncoding RNA Xist from one randomly chosen X chromosome in each female cell. The Xist locus must thus integrate both X-linked and developmental trans-regulatory factors in a dosage-dependent manner. Furthermore, the two alleles must coordinate to ensure inactivation of exactly one X chromosome per cell. In this review, we summarize the regulatory principles that govern the onset of XCI. We go on to provide an overview over the factors that have been implicated in Xist regulation and discuss recent advances in our understanding of how Xist's cis-regulatory landscape integrates information in a precise fashion.
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Affiliation(s)
- Till Schwämmle
- Otto Warburg Laboratories, Max Planck Institute for Molecular Genetics, Berlin, Germany. https://twitter.com/@TSchwammle
| | - Edda G Schulz
- Otto Warburg Laboratories, Max Planck Institute for Molecular Genetics, Berlin, Germany.
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6
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Abstract
X chromosome inactivation (XCI) is the process of silencing one of the X chromosomes in cells of the female mammal which ensures dosage compensation between the sexes. Although theoretically random in somatic tissues, the choice of which X chromosome is chosen to be inactivated can be biased in mice by genetic element(s) associated with the so-called X-controlling element (Xce). Although the Xce was first described and genetically localized nearly 40 y ago, its mode of action remains elusive. In the approach presented here, we identify a single long noncoding RNA (lncRNA) within the Xce locus, Lppnx, which may be the driving factor in the choice of which X chromosome will be inactivated in the developing female mouse embryo. Comparing weak and strong Xce alleles we show that Lppnx modulates the expression of Xist lncRNA, one of the key factors in XCI, by controlling the occupancy of pluripotency factors at Intron1 of Xist. This effect is counteracted by enhanced binding of Rex1 in DxPas34, another key element in XCI regulating the activity of Tsix lncRNA, the main antagonist of Xist, in the strong but not in the weak Xce allele. These results suggest that the different susceptibility for XCI observed in weak and strong Xce alleles results from differential transcription factor binding of Xist Intron 1 and DxPas34, and that Lppnx represents a decisive factor in explaining the action of the Xce.
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7
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Galupa R, Picard C, Servant N, Nora EP, Zhan Y, van Bemmel JG, El Marjou F, Johanneau C, Borensztein M, Ancelin K, Giorgetti L, Heard E. Inversion of a topological domain leads to restricted changes in its gene expression and affects interdomain communication. Development 2022; 149:275259. [PMID: 35502750 PMCID: PMC9148567 DOI: 10.1242/dev.200568] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Accepted: 02/28/2022] [Indexed: 01/02/2023]
Abstract
The interplay between the topological organization of the genome and the regulation of gene expression remains unclear. Depletion of molecular factors (e.g. CTCF) underlying topologically associating domains (TADs) leads to modest alterations in gene expression, whereas genomic rearrangements involving TAD boundaries disrupt normal gene expression and can lead to pathological phenotypes. Here, we targeted the TAD neighboring that of the noncoding transcript Xist, which controls X-chromosome inactivation. Inverting 245 kb within the TAD led to expected rearrangement of CTCF-based contacts but revealed heterogeneity in the 'contact' potential of different CTCF sites. Expression of most genes therein remained unaffected in mouse embryonic stem cells and during differentiation. Interestingly, expression of Xist was ectopically upregulated. The same inversion in mouse embryos led to biased Xist expression. Smaller inversions and deletions of CTCF clusters led to similar results: rearrangement of contacts and limited changes in local gene expression, but significant changes in Xist expression in embryos. Our study suggests that the wiring of regulatory interactions within a TAD can influence the expression of genes in neighboring TADs, highlighting the existence of mechanisms of inter-TAD communication.
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Affiliation(s)
- Rafael Galupa
- Mammalian Developmental Epigenetics Group, Genetics and Developmental Biology Unit, Institut Curie, PSL Research University, CNRS UMR3215, INSERM U934, Paris 75005, France
| | - Christel Picard
- Mammalian Developmental Epigenetics Group, Genetics and Developmental Biology Unit, Institut Curie, PSL Research University, CNRS UMR3215, INSERM U934, Paris 75005, France
| | - Nicolas Servant
- Bioinformatics, Biostatistics, Epidemiology and Computational Systems Unit, Institut Curie, PSL Research University, INSERM U900, Paris 75005, France.,MINES ParisTech, PSL Research University, CBIO-Centre for Computational Biology, Paris 75006, France
| | - Elphège P Nora
- Mammalian Developmental Epigenetics Group, Genetics and Developmental Biology Unit, Institut Curie, PSL Research University, CNRS UMR3215, INSERM U934, Paris 75005, France
| | - Yinxiu Zhan
- Friedrich Miescher Institute for Biomedical Research, Basel 4058, Switzerland.,University of Basel, Basel 4001, Switzerland
| | - Joke G van Bemmel
- Mammalian Developmental Epigenetics Group, Genetics and Developmental Biology Unit, Institut Curie, PSL Research University, CNRS UMR3215, INSERM U934, Paris 75005, France
| | | | | | - Maud Borensztein
- Mammalian Developmental Epigenetics Group, Genetics and Developmental Biology Unit, Institut Curie, PSL Research University, CNRS UMR3215, INSERM U934, Paris 75005, France
| | - Katia Ancelin
- Mammalian Developmental Epigenetics Group, Genetics and Developmental Biology Unit, Institut Curie, PSL Research University, CNRS UMR3215, INSERM U934, Paris 75005, France
| | - Luca Giorgetti
- Friedrich Miescher Institute for Biomedical Research, Basel 4058, Switzerland
| | - Edith Heard
- Mammalian Developmental Epigenetics Group, Genetics and Developmental Biology Unit, Institut Curie, PSL Research University, CNRS UMR3215, INSERM U934, Paris 75005, France.,Collège de France, Paris 75231, France
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8
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Florini F, Visone JE, Deitsch KW. Shared Mechanisms for Mutually Exclusive Expression and Antigenic Variation by Protozoan Parasites. Front Cell Dev Biol 2022; 10:852239. [PMID: 35350381 PMCID: PMC8957917 DOI: 10.3389/fcell.2022.852239] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Accepted: 02/17/2022] [Indexed: 01/05/2023] Open
Abstract
Cellular decision-making at the level of gene expression is a key process in the development and evolution of every organism. Variations in gene expression can lead to phenotypic diversity and the development of subpopulations with adaptive advantages. A prime example is the mutually exclusive activation of a single gene from within a multicopy gene family. In mammals, this ranges from the activation of one of the two immunoglobulin (Ig) alleles to the choice in olfactory sensory neurons of a single odorant receptor (OR) gene from a family of more than 1,000. Similarly, in parasites like Trypanosoma brucei, Giardia lamblia or Plasmodium falciparum, the process of antigenic variation required to escape recognition by the host immune system involves the monoallelic expression of vsg, vsp or var genes, respectively. Despite the importance of this process, understanding how this choice is made remains an enigma. The development of powerful techniques such as single cell RNA-seq and Hi-C has provided new insights into the mechanisms these different systems employ to achieve monoallelic gene expression. Studies utilizing these techniques have shown how the complex interplay between nuclear architecture, physical interactions between chromosomes and different chromatin states lead to single allele expression. Additionally, in several instances it has been observed that high-level expression of a single gene is preceded by a transient state where multiple genes are expressed at a low level. In this review, we will describe and compare the different strategies that organisms have evolved to choose one gene from within a large family and how parasites employ this strategy to ensure survival within their hosts.
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Affiliation(s)
| | | | - Kirk W. Deitsch
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, NY, United States
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9
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Mechanisms of Choice in X-Chromosome Inactivation. Cells 2022; 11:cells11030535. [PMID: 35159344 PMCID: PMC8833938 DOI: 10.3390/cells11030535] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Revised: 01/30/2022] [Accepted: 01/31/2022] [Indexed: 12/04/2022] Open
Abstract
Early in development, placental and marsupial mammals harbouring at least two X chromosomes per nucleus are faced with a choice that affects the rest of their lives: which of those X chromosomes to transcriptionally inactivate. This choice underlies phenotypical diversity in the composition of tissues and organs and in their response to the environment, and can determine whether an individual will be healthy or affected by an X-linked disease. Here, we review our current understanding of the process of choice during X-chromosome inactivation and its implications, focusing on the strategies evolved by different mammalian lineages and on the known and unknown molecular mechanisms and players involved.
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10
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Gene regulation in time and space during X-chromosome inactivation. Nat Rev Mol Cell Biol 2022; 23:231-249. [PMID: 35013589 DOI: 10.1038/s41580-021-00438-7] [Citation(s) in RCA: 97] [Impact Index Per Article: 48.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/18/2021] [Indexed: 12/21/2022]
Abstract
X-chromosome inactivation (XCI) is the epigenetic mechanism that ensures X-linked dosage compensation between cells of females (XX karyotype) and males (XY). XCI is essential for female embryos to survive through development and requires the accurate spatiotemporal regulation of many different factors to achieve remarkable chromosome-wide gene silencing. As a result of XCI, the active and inactive X chromosomes are functionally and structurally different, with the inactive X chromosome undergoing a major conformational reorganization within the nucleus. In this Review, we discuss the multiple layers of genetic and epigenetic regulation that underlie initiation of XCI during development and then maintain it throughout life, in light of the most recent findings in this rapidly advancing field. We discuss exciting new insights into the regulation of X inactive-specific transcript (XIST), the trigger and master regulator of XCI, and into the mechanisms and dynamics that underlie the silencing of nearly all X-linked genes. Finally, given the increasing interest in understanding the impact of chromosome organization on gene regulation, we provide an overview of the factors that are thought to reshape the 3D structure of the inactive X chromosome and of the relevance of such structural changes for XCI establishment and maintenance.
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11
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Gjaltema RAF, Schwämmle T, Kautz P, Robson M, Schöpflin R, Ravid Lustig L, Brandenburg L, Dunkel I, Vechiatto C, Ntini E, Mutzel V, Schmiedel V, Marsico A, Mundlos S, Schulz EG. Distal and proximal cis-regulatory elements sense X chromosome dosage and developmental state at the Xist locus. Mol Cell 2022; 82:190-208.e17. [PMID: 34932975 DOI: 10.1016/j.molcel.2021.11.023] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 11/22/2021] [Accepted: 11/23/2021] [Indexed: 12/15/2022]
Abstract
Developmental genes such as Xist, which initiates X chromosome inactivation, are controlled by complex cis-regulatory landscapes, which decode multiple signals to establish specific spatiotemporal expression patterns. Xist integrates information on X chromosome dosage and developmental stage to trigger X inactivation in the epiblast specifically in female embryos. Through a pooled CRISPR screen in differentiating mouse embryonic stem cells, we identify functional enhancer elements of Xist at the onset of random X inactivation. Chromatin profiling reveals that X-dosage controls the promoter-proximal region, while differentiation cues activate several distal enhancers. The strongest distal element lies in an enhancer cluster associated with a previously unannotated Xist-enhancing regulatory transcript, which we named Xert. Developmental cues and X-dosage are thus decoded by distinct regulatory regions, which cooperate to ensure female-specific Xist upregulation at the correct developmental time. With this study, we start to disentangle how multiple, functionally distinct regulatory elements interact to generate complex expression patterns in mammals.
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Affiliation(s)
- Rutger A F Gjaltema
- Otto Warburg Laboratories, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany
| | - Till Schwämmle
- Otto Warburg Laboratories, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany
| | - Pauline Kautz
- Otto Warburg Laboratories, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany
| | - Michael Robson
- Development and Disease Group, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany; Medical Research Council Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh EH4 2XU, Edinburgh, UK
| | - Robert Schöpflin
- Development and Disease Group, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany; Institute for Medical and Human Genetics, Charité-Universitätsmedizin Berlin, 13353 Berlin, Germany; Department of Computational Molecular Biology, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany
| | - Liat Ravid Lustig
- Otto Warburg Laboratories, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany
| | - Lennart Brandenburg
- Otto Warburg Laboratories, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany
| | - Ilona Dunkel
- Otto Warburg Laboratories, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany
| | - Carolina Vechiatto
- Otto Warburg Laboratories, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany
| | - Evgenia Ntini
- Otto Warburg Laboratories, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany
| | - Verena Mutzel
- Otto Warburg Laboratories, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany
| | - Vera Schmiedel
- Otto Warburg Laboratories, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany
| | - Annalisa Marsico
- Computational Health Center, Helmholtz Center München, 85764 Neuherberg, Germany
| | - Stefan Mundlos
- Development and Disease Group, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany; Institute for Medical and Human Genetics, Charité-Universitätsmedizin Berlin, 13353 Berlin, Germany
| | - Edda G Schulz
- Otto Warburg Laboratories, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany.
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12
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Robert-Finestra T, Tan BF, Mira-Bontenbal H, Timmers E, Gontan C, Merzouk S, Giaimo BD, Dossin F, van IJcken WFJ, Martens JWM, Borggrefe T, Heard E, Gribnau J. SPEN is required for Xist upregulation during initiation of X chromosome inactivation. Nat Commun 2021; 12:7000. [PMID: 34853312 PMCID: PMC8636516 DOI: 10.1038/s41467-021-27294-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Accepted: 11/08/2021] [Indexed: 01/11/2023] Open
Abstract
At initiation of X chromosome inactivation (XCI), Xist is monoallelically upregulated from the future inactive X (Xi) chromosome, overcoming repression by its antisense transcript Tsix. Xist recruits various chromatin remodelers, amongst them SPEN, which are involved in silencing of X-linked genes in cis and establishment of the Xi. Here, we show that SPEN plays an important role in initiation of XCI. Spen null female mouse embryonic stem cells (ESCs) are defective in Xist upregulation upon differentiation. We find that Xist-mediated SPEN recruitment to the Xi chromosome happens very early in XCI, and that SPEN-mediated silencing of the Tsix promoter is required for Xist upregulation. Accordingly, failed Xist upregulation in Spen-/- ESCs can be rescued by concomitant removal of Tsix. These findings indicate that SPEN is not only required for the establishment of the Xi, but is also crucial in initiation of the XCI process.
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Affiliation(s)
- Teresa Robert-Finestra
- Department of Developmental Biology, Erasmus University Medical Center, Oncode Institute, 3015GD, Rotterdam, The Netherlands
| | - Beatrice F Tan
- Department of Developmental Biology, Erasmus University Medical Center, Oncode Institute, 3015GD, Rotterdam, The Netherlands
| | - Hegias Mira-Bontenbal
- Department of Developmental Biology, Erasmus University Medical Center, Oncode Institute, 3015GD, Rotterdam, The Netherlands
| | - Erika Timmers
- Department of Developmental Biology, Erasmus University Medical Center, Oncode Institute, 3015GD, Rotterdam, The Netherlands
| | - Cristina Gontan
- Department of Developmental Biology, Erasmus University Medical Center, Oncode Institute, 3015GD, Rotterdam, The Netherlands
| | - Sarra Merzouk
- Department of Developmental Biology, Erasmus University Medical Center, Oncode Institute, 3015GD, Rotterdam, The Netherlands
| | | | - François Dossin
- European Molecular Biology Laboratory, Director's Research, 69117, Heidelberg, Germany
| | - Wilfred F J van IJcken
- Center for Biomics, Erasmus University Medical Center, 3015CN, Rotterdam, The Netherlands
| | - John W M Martens
- Department of Medical Oncology, Erasmus MC Cancer Institute and Cancer Genomics Netherlands, Erasmus University Medical Center, 3015CN, Rotterdam, The Netherlands
| | - Tilman Borggrefe
- Institute of Biochemistry, University of Giessen, 35392, Giessen, Germany
| | - Edith Heard
- European Molecular Biology Laboratory, Director's Research, 69117, Heidelberg, Germany
| | - Joost Gribnau
- Department of Developmental Biology, Erasmus University Medical Center, Oncode Institute, 3015GD, Rotterdam, The Netherlands.
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13
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Enervald E, Powell LM, Boteva L, Foti R, Blanes Ruiz N, Kibar G, Piszczek A, Cavaleri F, Vingron M, Cerase A, Buonomo SBC. RIF1 and KAP1 differentially regulate the choice of inactive versus active X chromosomes. EMBO J 2021; 40:e105862. [PMID: 34786738 DOI: 10.15252/embj.2020105862] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2020] [Revised: 10/05/2021] [Accepted: 10/19/2021] [Indexed: 11/09/2022] Open
Abstract
The onset of random X chromosome inactivation in mouse requires the switch from a symmetric to an asymmetric state, where the identities of the future inactive and active X chromosomes are assigned. This process is known as X chromosome choice. Here, we show that RIF1 and KAP1 are two fundamental factors for the definition of this transcriptional asymmetry. We found that at the onset of differentiation of mouse embryonic stem cells (mESCs), biallelic up-regulation of the long non-coding RNA Tsix weakens the symmetric association of RIF1 with the Xist promoter. The Xist allele maintaining the association with RIF1 goes on to up-regulate Xist RNA expression in a RIF1-dependent manner. Conversely, the promoter that loses RIF1 gains binding of KAP1, and KAP1 is required for the increase in Tsix levels preceding the choice. We propose that the mutual exclusion of Tsix and RIF1, and of RIF1 and KAP1, at the Xist promoters establish a self-sustaining loop that transforms an initially stochastic event into a stably inherited asymmetric X-chromosome state.
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Affiliation(s)
- Elin Enervald
- Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, UK.,Epigenetics & Neurobiology Unit, European Molecular Biology Laboratory (EMBL Rome), Monterotondo, Italy
| | - Lynn Marie Powell
- Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, UK
| | - Lora Boteva
- Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, UK
| | - Rossana Foti
- Epigenetics & Neurobiology Unit, European Molecular Biology Laboratory (EMBL Rome), Monterotondo, Italy
| | - Nerea Blanes Ruiz
- Blizard Institute, Centre for Genomics and Child Health, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Gözde Kibar
- Max-Planck-Institut fuer molekulare Genetik, Berlin, Germany
| | - Agnieszka Piszczek
- Epigenetics & Neurobiology Unit, European Molecular Biology Laboratory (EMBL Rome), Monterotondo, Italy
| | - Fatima Cavaleri
- Epigenetics & Neurobiology Unit, European Molecular Biology Laboratory (EMBL Rome), Monterotondo, Italy
| | - Martin Vingron
- Max-Planck-Institut fuer molekulare Genetik, Berlin, Germany
| | - Andrea Cerase
- Blizard Institute, Centre for Genomics and Child Health, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Sara B C Buonomo
- Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, UK.,Epigenetics & Neurobiology Unit, European Molecular Biology Laboratory (EMBL Rome), Monterotondo, Italy
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14
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Szanto A, Aguilar R, Kesner B, Blum R, Wang D, Cifuentes-Rojas C, Del Rosario BC, Kis-Toth K, Lee JT. A disproportionate impact of G9a methyltransferase deficiency on the X chromosome. Genes Dev 2021; 35:1035-1054. [PMID: 34168040 PMCID: PMC8247598 DOI: 10.1101/gad.337592.120] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Accepted: 05/27/2021] [Indexed: 01/05/2023]
Abstract
In this study from Szanto et al., the authors investigated the role of G9a, a histone methyltransferase responsible for the dimethylation of histone H3 at lysine 9 (H3K9me2) that plays key roles in transcriptional silencing of developmentally regulated genes, in X-chromosome inactivation (XCI). They found a female-specific function of G9a and demonstrate that deleting G9a has a disproportionate impact on the X chromosome relative to the rest of the genome, and show RNA tethers G9a for allele-specific targeting of the H3K9me2 modification and the G9a–RNA interaction is essential for XCI. G9a is a histone methyltransferase responsible for the dimethylation of histone H3 at lysine 9 (H3K9me2). G9a plays key roles in transcriptional silencing of developmentally regulated genes, but its role in X-chromosome inactivation (XCI) has been under debate. Here, we uncover a female-specific function of G9a and demonstrate that deleting G9a has a disproportionate impact on the X chromosome relative to the rest of the genome. G9a deficiency causes a failure of XCI and female-specific hypersensitivity to drug inhibition of H3K9me2. We show that G9a interacts with Tsix and Xist RNAs, and that competitive inhibition of the G9a-RNA interaction recapitulates the XCI defect. During XCI, Xist recruits G9a to silence X-linked genes on the future inactive X. In parallel on the future Xa, Tsix recruits G9a to silence Xist in cis. Thus, RNA tethers G9a for allele-specific targeting of the H3K9me2 modification and the G9a-RNA interaction is essential for XCI.
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Affiliation(s)
- Attila Szanto
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts 02114, USA.,Department of Genetics, The Blavatnik Institute, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Rodrigo Aguilar
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts 02114, USA.,Department of Genetics, The Blavatnik Institute, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Barry Kesner
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts 02114, USA.,Department of Genetics, The Blavatnik Institute, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Roy Blum
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts 02114, USA.,Department of Genetics, The Blavatnik Institute, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Danni Wang
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts 02114, USA.,Department of Genetics, The Blavatnik Institute, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Catherine Cifuentes-Rojas
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts 02114, USA.,Department of Genetics, The Blavatnik Institute, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Brian C Del Rosario
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts 02114, USA.,Department of Genetics, The Blavatnik Institute, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Katalin Kis-Toth
- Department of Rheumatology, Beth Israel Deaconess Medical Center, Harvard Medical School Boston, Massachusetts 02115, USA
| | - Jeannie T Lee
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts 02114, USA.,Department of Genetics, The Blavatnik Institute, Harvard Medical School, Boston, Massachusetts 02115, USA
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15
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Yin H, Wei C, Lee JT. Revisiting the consequences of deleting the X inactivation center. Proc Natl Acad Sci U S A 2021; 118:e2102683118. [PMID: 34161282 PMCID: PMC8237661 DOI: 10.1073/pnas.2102683118] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Mammalian cells equalize X-linked dosages between the male (XY) and female (XX) sexes by silencing one X chromosome in the female sex. This process, known as "X chromosome inactivation" (XCI), requires a master switch within the X inactivation center (Xic). The Xic spans several hundred kilobases in the mouse and includes a number of regulatory noncoding genes that produce functional transcripts. Over three decades, transgenic and deletional analyses have demonstrated both the necessity and sufficiency of the Xic to induce XCI, including the steps of X chromosome counting, choice, and initiation of whole-chromosome silencing. One recent study, however, reported that deleting the noncoding sequences of the Xic surprisingly had no effect for XCI and attributed a sufficiency to drive counting to the coding gene, Rnf12/Rlim Here, we revisit the question by creating independent Xic deletion cell lines. Multiple independent clones carrying heterozygous deletions of the Xic display an inability to up-regulate Xist expression, consistent with a counting defect. This defect is rescued by a second site mutation in Tsix occurring in trans, bypassing the defect in counting. These findings reaffirm the essential nature of noncoding Xic elements for the initiation of XCI.
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Affiliation(s)
- Hao Yin
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114
- Department of Genetics, Harvard Medical School, Boston, MA 02114
| | - Chunyao Wei
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114
- Department of Genetics, Harvard Medical School, Boston, MA 02114
| | - Jeannie T Lee
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114;
- Department of Genetics, Harvard Medical School, Boston, MA 02114
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16
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Mutzel V, Schulz EG. Dosage Sensing, Threshold Responses, and Epigenetic Memory: A Systems Biology Perspective on Random X-Chromosome Inactivation. Bioessays 2021; 42:e1900163. [PMID: 32189388 DOI: 10.1002/bies.201900163] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2019] [Revised: 01/27/2020] [Indexed: 02/06/2023]
Abstract
X-chromosome inactivation ensures dosage compensation between the sexes in mammals by randomly choosing one out of the two X chromosomes in females for inactivation. This process imposes a plethora of questions: How do cells count their X chromosome number and ensure that exactly one stays active? How do they randomly choose one of two identical X chromosomes for inactivation? And how do they stably maintain this state of monoallelic expression? Here, different regulatory concepts and their plausibility are evaluated in the context of theoretical studies that have investigated threshold behavior, ultrasensitivity, and bistability through mathematical modeling. It is discussed how a twofold difference between a single and a double dose of X-linked genes might be converted to an all-or-nothing response and how mutually exclusive expression can be initiated and maintained. Finally, candidate factors that might mediate the proposed regulatory principles are reviewed.
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Affiliation(s)
- Verena Mutzel
- Otto Warburg Laboratories, Max Planck Institute for Molecular Genetics, Berlin, 14195, Germany
| | - Edda G Schulz
- Otto Warburg Laboratories, Max Planck Institute for Molecular Genetics, Berlin, 14195, Germany
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17
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Sun KY, Oreper D, Schoenrock SA, McMullan R, Giusti-Rodríguez P, Zhabotynsky V, Miller DR, Tarantino LM, Pardo-Manuel de Villena F, Valdar W. Bayesian modeling of skewed X inactivation in genetically diverse mice identifies a novel Xce allele associated with copy number changes. Genetics 2021; 218:6162162. [PMID: 33693696 DOI: 10.1093/genetics/iyab034] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2020] [Accepted: 02/15/2021] [Indexed: 11/13/2022] Open
Abstract
Female mammals are functional mosaics of their parental X-linked gene expression due to X chromosome inactivation (XCI). This process inactivates one copy of the X chromosome in each cell during embryogenesis and that state is maintained clonally through mitosis. In mice, the choice of which parental X chromosome remains active is determined by the X chromosome controlling element (Xce), which has been mapped to a 176-kb candidate interval. A series of functional Xce alleles has been characterized or inferred for classical inbred strains based on biased, or skewed, inactivation of the parental X chromosomes in crosses between strains. To further explore the function structure basis and location of the Xce, we measured allele-specific expression of X-linked genes in a large population of F1 females generated from Collaborative Cross (CC) strains. Using published sequence data and applying a Bayesian "Pólya urn" model of XCI skew, we report two major findings. First, inter-individual variability in XCI suggests mouse epiblasts contain on average 20-30 cells contributing to brain. Second, CC founder strain NOD/ShiLtJ has a novel and unique functional allele, Xceg, that is the weakest in the Xce allelic series. Despite phylogenetic analysis confirming that NOD/ShiLtJ carries a haplotype almost identical to the well-characterized C57BL/6J (Xceb), we observed unexpected patterns of XCI skewing in females carrying the NOD/ShiLtJ haplotype within the Xce. Copy number variation is common at the Xce locus and we conclude that the observed allelic series is a product of independent and recurring duplications shared between weak Xce alleles.
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Affiliation(s)
- Kathie Y Sun
- Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.,Bioinformatics and Computational Biology Curriculum, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Daniel Oreper
- Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.,Bioinformatics and Computational Biology Curriculum, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Sarah A Schoenrock
- Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.,Neuroscience Curriculum, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Rachel McMullan
- Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.,Genetics and Molecular Biology Curriculum, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Paola Giusti-Rodríguez
- Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Vasyl Zhabotynsky
- Department of Biostatistics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Darla R Miller
- Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.,Lineberger Comprehensive Cancer Center, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Lisa M Tarantino
- Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.,Division of Pharmacotherapy and Experimental Therapeutics, Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Fernando Pardo-Manuel de Villena
- Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.,Lineberger Comprehensive Cancer Center, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - William Valdar
- Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.,Lineberger Comprehensive Cancer Center, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
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18
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Lobato R. A quantum mechanical approach to random X chromosome inactivation. AIMS BIOPHYSICS 2021. [DOI: 10.3934/biophy.2021026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
<abstract>
<p>The X chromosome inactivation is an essential mechanism in mammals' development, that despite having been investigated for 60 years, many questions about its choice process have yet to be fully answered. Therefore, a theoretical model was proposed here for the first time in an attempt to explain this puzzling phenomenon through a quantum mechanical approach. Based on previous data, this work theoretically demonstrates how a shared delocalized proton at a key base pair position could explain the random, instantaneous, and mutually exclusive nature of the choice process in X chromosome inactivation. The main purpose of this work is to contribute to a comprehensive understanding of the X inactivation mechanism with a model proposal that can complement the existent ones, along with introducing a quantum mechanical approach that could be applied to other cell differentiation mechanisms.</p>
</abstract>
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19
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Galupa R, Nora EP, Worsley-Hunt R, Picard C, Gard C, van Bemmel JG, Servant N, Zhan Y, El Marjou F, Johanneau C, Diabangouaya P, Le Saux A, Lameiras S, Pipoli da Fonseca J, Loos F, Gribnau J, Baulande S, Ohler U, Giorgetti L, Heard E. A Conserved Noncoding Locus Regulates Random Monoallelic Xist Expression across a Topological Boundary. Mol Cell 2020; 77:352-367.e8. [PMID: 31759823 PMCID: PMC6964159 DOI: 10.1016/j.molcel.2019.10.030] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Revised: 09/08/2019] [Accepted: 10/17/2019] [Indexed: 12/11/2022]
Abstract
cis-Regulatory communication is crucial in mammalian development and is thought to be restricted by the spatial partitioning of the genome in topologically associating domains (TADs). Here, we discovered that the Xist locus is regulated by sequences in the neighboring TAD. In particular, the promoter of the noncoding RNA Linx (LinxP) acts as a long-range silencer and influences the choice of X chromosome to be inactivated. This is independent of Linx transcription and independent of any effect on Tsix, the antisense regulator of Xist that shares the same TAD as Linx. Unlike Tsix, LinxP is well conserved across mammals, suggesting an ancestral mechanism for random monoallelic Xist regulation. When introduced in the same TAD as Xist, LinxP switches from a silencer to an enhancer. Our study uncovers an unsuspected regulatory axis for X chromosome inactivation and a class of cis-regulatory effects that may exploit TAD partitioning to modulate developmental decisions.
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Affiliation(s)
- Rafael Galupa
- Mammalian Developmental Epigenetics Group, Genetics and Developmental Biology Unit, Institut Curie, PSL Research University, CNRS UMR3215, INSERM U934, Paris, France
| | - Elphège Pierre Nora
- Mammalian Developmental Epigenetics Group, Genetics and Developmental Biology Unit, Institut Curie, PSL Research University, CNRS UMR3215, INSERM U934, Paris, France
| | - Rebecca Worsley-Hunt
- Berlin Institute for Medical Systems Biology, Max Delbruck Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany
| | - Christel Picard
- Mammalian Developmental Epigenetics Group, Genetics and Developmental Biology Unit, Institut Curie, PSL Research University, CNRS UMR3215, INSERM U934, Paris, France
| | - Chris Gard
- Mammalian Developmental Epigenetics Group, Genetics and Developmental Biology Unit, Institut Curie, PSL Research University, CNRS UMR3215, INSERM U934, Paris, France
| | - Joke Gerarda van Bemmel
- Mammalian Developmental Epigenetics Group, Genetics and Developmental Biology Unit, Institut Curie, PSL Research University, CNRS UMR3215, INSERM U934, Paris, France
| | - Nicolas Servant
- Bioinformatics, Biostatistics, Epidemiology and Computational Systems Unit, Institut Curie, PSL Research University, INSERM U900, Paris, France; MINES ParisTech, PSL Research University, Centre for Computational Biology (CBIO), Paris, France
| | - Yinxiu Zhan
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland; University of Basel, Basel, Switzerland
| | | | | | - Patricia Diabangouaya
- Mammalian Developmental Epigenetics Group, Genetics and Developmental Biology Unit, Institut Curie, PSL Research University, CNRS UMR3215, INSERM U934, Paris, France
| | - Agnès Le Saux
- Mammalian Developmental Epigenetics Group, Genetics and Developmental Biology Unit, Institut Curie, PSL Research University, CNRS UMR3215, INSERM U934, Paris, France
| | - Sonia Lameiras
- Institut Curie Genomics of Excellence (ICGex) Platform, Institut Curie, Paris, France
| | | | - Friedemann Loos
- Department of Developmental Biology, Erasmus MC, University Medical Center, Rotterdam, the Netherlands
| | - Joost Gribnau
- Department of Developmental Biology, Erasmus MC, University Medical Center, Rotterdam, the Netherlands
| | - Sylvain Baulande
- Institut Curie Genomics of Excellence (ICGex) Platform, Institut Curie, Paris, France
| | - Uwe Ohler
- Berlin Institute for Medical Systems Biology, Max Delbruck Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany; Department of Biology, Humboldt University, Berlin, Germany
| | - Luca Giorgetti
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
| | - Edith Heard
- Mammalian Developmental Epigenetics Group, Genetics and Developmental Biology Unit, Institut Curie, PSL Research University, CNRS UMR3215, INSERM U934, Paris, France; Collège de France, Paris, France.
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20
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Abstract
In mammals, dosage compensation of sex chromosomal genes between females (XX) and males (XY) is achieved through X-chromosome inactivation (XCI). The X-linked X-inactive-specific transcript (Xist) long noncoding RNA is indispensable for XCI and initiates the process early during development by spreading in cis across the X chromosome from which it is transcribed. During XCI, Xist RNA triggers gene silencing, recruits a plethora of chromatin modifying factors, and drives a major structural reorganization of the X chromosome. Here, we review our knowledge of the multitude of epigenetic events orchestrated by Xist RNA to allow female mammals to survive through embryonic development by establishing and maintaining proper dosage compensation. In particular, we focus on recent studies characterizing the interaction partners of Xist RNA, and we discuss how they have affected the field by addressing long-standing controversies or by giving rise to new research perspectives that are currently being explored. This review is dedicated to the memory of Denise Barlow, pioneer of genomic imprinting and functional long noncoding RNAs (lncRNAs), whose work has revolutionized the epigenetics field and continues to inspire generations of scientists.
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21
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The bipartite TAD organization of the X-inactivation center ensures opposing developmental regulation of Tsix and Xist. Nat Genet 2019; 51:1024-1034. [PMID: 31133748 PMCID: PMC6551226 DOI: 10.1038/s41588-019-0412-0] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2018] [Accepted: 04/04/2019] [Indexed: 01/08/2023]
Abstract
The mouse X-inactivation center (Xic) locus represents a powerful model for understanding the links between genome architecture and gene regulation, with the non-coding genes Xist and Tsix showing opposite developmental expression patterns while being organized as an overlapping sense/antisense unit. The Xic is organized into two topologically associating domains (TADs) but the role of this architecture in orchestrating cis-regulatory information remains elusive. To explore this, we generated genomic inversions that swap the Xist/Tsix transcriptional unit and place their promoters in each other’s TAD. We found that this led to a switch in their expression dynamics: Xist became precociously and ectopically up-regulated, both in male and female pluripotent cells, while Tsix expression aberrantly persisted during differentiation. The topological partitioning of the Xic is thus critical to ensure proper developmental timing of X inactivation. Our study illustrates how the genomic architecture of cis-regulatory landscapes can affect the regulation of mammalian developmental processes.
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22
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Yang F, Wen S, Zhang Y, Xu Y, Lv H, Zhu Y, Wang M, Su P, Huang C, Tian Z. Identifying potential metastasis-related long non-coding RNAs, microRNAs, and message RNAs in the esophageal squamous cell carcinoma. J Cell Biochem 2019; 120:13202-13215. [PMID: 30891809 DOI: 10.1002/jcb.28594] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Revised: 12/20/2018] [Accepted: 01/07/2019] [Indexed: 12/14/2022]
Abstract
Esophageal squamous cell carcinoma (ESCC) is the predominant form with the highest incidence. We aimed to find metastasis-related differentially expressed long noncoding RNAs (lncRNAs), microRNAs (miRNAs), and messenger RNA (mRNAs) in ESCC. We first obtained the lncRNAs, miRNAs, and mRNAs profiles. The differentially expressed lncRNAs, miRNAs, and mRNAs were obtained, followed by the functional annotation. Then the interaction networks of miRNA-mRNA, lncRNA-mRNA coexpression, lncRNA-miRNA, and lncRNA-miRNA-mRNA were constructed. In addition, systematic expression pattern analysis of differentially expressed lncRNAs, miRNA, and mRNA in the normal, metastasis, and nonmetastasis was performed. Survivability of differentially expressed lncRNAs, miRNAs, and mRNA was analyzed. A total of 613 differentially expressed lncRNAs, 35 differentially expressed miRNAs, and 1586 differentially expressed mRNAs were obtained. Several interactions of H19-hsa-mir-222-chromobox 2 (CBX2), H19-hsa-mir-330-phosphoinositide-3-kinase regulatory subunit 4 (PIK3R4), KCNQ1 opposite strand/antisense transcript 1 (KCNQ1OT1)/CTB-89H12.4-hsa-mir-374a-vascular endothelial growth factor A (VEGFA), MALAT1/X inactive specific transcript (XIST)/XIST antisense RNA (TSIX)-hsa-mir-340-tumor necrosis factor receptor superfamily member 10A (NFRSF10A) were identified to play key roles in the metastasis of ESCC. In addition, KCNQ1OT1, TSIX, and XIST were significantly associated with the survival time of patients. In conclusion, our study may be helpful in understanding the pathological mechanism and providing new diagnostic and therapeutic biomarkers for ESCC.
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Affiliation(s)
- Fei Yang
- Department of Otolaryngology, The Fourth Hospital of Hebei Medical University, Shijiazhuang, Hebei, China
| | - Shiwang Wen
- Department of Thoracic Surgery, The Fourth Hospital of Hebei Medical University, Shijiazhuang, Hebei, China
| | - Yuefeng Zhang
- Department of Thoracic Surgery, The Fourth Hospital of Hebei Medical University, Shijiazhuang, Hebei, China
| | - Yanzhao Xu
- Department of Thoracic Surgery, The Fourth Hospital of Hebei Medical University, Shijiazhuang, Hebei, China
| | - Huilai Lv
- Department of Thoracic Surgery, The Fourth Hospital of Hebei Medical University, Shijiazhuang, Hebei, China
| | - Yonggang Zhu
- Department of Thoracic Surgery, The Fourth Hospital of Hebei Medical University, Shijiazhuang, Hebei, China
| | - Mingbo Wang
- Department of Thoracic Surgery, The Fourth Hospital of Hebei Medical University, Shijiazhuang, Hebei, China
| | - Peng Su
- Department of Thoracic Surgery, The Fourth Hospital of Hebei Medical University, Shijiazhuang, Hebei, China
| | - Chao Huang
- Department of Thoracic Surgery, The Fourth Hospital of Hebei Medical University, Shijiazhuang, Hebei, China
| | - Ziqiang Tian
- Department of Thoracic Surgery, The Fourth Hospital of Hebei Medical University, Shijiazhuang, Hebei, China
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23
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Galupa R, Heard E. X-Chromosome Inactivation: A Crossroads Between Chromosome Architecture and Gene Regulation. Annu Rev Genet 2018; 52:535-566. [PMID: 30256677 DOI: 10.1146/annurev-genet-120116-024611] [Citation(s) in RCA: 144] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
In somatic nuclei of female therian mammals, the two X chromosomes display very different chromatin states: One X is typically euchromatic and transcriptionally active, and the other is mostly silent and forms a cytologically detectable heterochromatic structure termed the Barr body. These differences, which arise during female development as a result of X-chromosome inactivation (XCI), have been the focus of research for many decades. Initial approaches to define the structure of the inactive X chromosome (Xi) and its relationship to gene expression mainly involved microscopy-based approaches. More recently, with the advent of genomic techniques such as chromosome conformation capture, molecular details of the structure and expression of the Xi have been revealed. Here, we review our current knowledge of the 3D organization of the mammalian X-chromosome chromatin and discuss its relationship with gene activity in light of the initiation, spreading, and maintenance of XCI, as well as escape from gene silencing.
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Affiliation(s)
- Rafael Galupa
- Genetics and Developmental Biology Unit and Mammalian Developmental Epigenetics Group, Institut Curie, PSL Research University, CNRS UMR3215, INSERM U934, 75248 Paris, France; .,Current affiliation: Developmental Biology Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Edith Heard
- Genetics and Developmental Biology Unit and Mammalian Developmental Epigenetics Group, Institut Curie, PSL Research University, CNRS UMR3215, INSERM U934, 75248 Paris, France; .,Collège de France, 75231 Paris, France
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24
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Sado T. What makes the maternal X chromosome resistant to undergoing imprinted X inactivation? Philos Trans R Soc Lond B Biol Sci 2018; 372:rstb.2016.0365. [PMID: 28947661 DOI: 10.1098/rstb.2016.0365] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/24/2017] [Indexed: 11/12/2022] Open
Abstract
In the mouse, while either X chromosome is chosen for inactivation in a random fashion in the embryonic tissue, the paternally derived X chromosome is preferentially inactivated in the extraembryonic tissues. It has been shown that the maternal X chromosome is imprinted so as not to undergo inactivation in the extraembryonic tissues. X-linked noncoding Xist RNA becomes upregulated on the X chromosome that is to be inactivated. An antisense noncoding RNA, Tsix, which occurs at the Xist locus and has been shown to negatively regulate Xist expression in cis, is imprinted to be expressed from the maternal X in the extraembryonic tissues. Although Tsix appears to be responsible for the imprint laid on the maternal X, those who disagree with this idea would point out the fact that Tsix has not yet been expressed from the maternal X when Xist becomes upregulated on the paternal but not the maternal X at the onset of imprinted X-inactivation in preimplantation embryos. Recent studies have demonstrated, however, that there is a prominent difference in the chromatin structure at the Xist locus depending on the parental origin, which I suggest might account for the repression of maternal Xist in the absence of maternal Tsix at the preimplantation stages.This article is part of the themed issue 'X-chromosome inactivation: a tribute to Mary Lyon'.
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Affiliation(s)
- Takashi Sado
- Department of Bioscience, Graduate School of Agriculture, Kindai University, 3327-204, Nakamachi, Nara 631-8505, Japan
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25
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26
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Wang Y, Li Y, Yue M, Wang J, Kumar S, Wechsler-Reya RJ, Zhang Z, Ogawa Y, Kellis M, Duester G, Zhao JC. N 6-methyladenosine RNA modification regulates embryonic neural stem cell self-renewal through histone modifications. Nat Neurosci 2018; 21:195-206. [PMID: 29335608 PMCID: PMC6317335 DOI: 10.1038/s41593-017-0057-1] [Citation(s) in RCA: 299] [Impact Index Per Article: 49.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2017] [Accepted: 12/04/2017] [Indexed: 12/20/2022]
Abstract
Internal N6-methyladenosine (m6A) modification is widespread in messenger RNAs (mRNAs) and is catalyzed by heterodimers of methyltransferase-like protein 3 (Mettl3) and Mettl14. To understand the role of m6A in development, we deleted Mettl14 in embryonic neural stem cells (NSCs) in a mouse model. Phenotypically, NSCs lacking Mettl14 displayed markedly decreased proliferation and premature differentiation, suggesting that m6A modification enhances NSC self-renewal. Decreases in the NSC pool led to a decreased number of late-born neurons during cortical neurogenesis. Mechanistically, we discovered a genome-wide increase in specific histone modifications in Mettl14 knockout versus control NSCs. These changes correlated with altered gene expression and observed cellular phenotypes, suggesting functional significance of altered histone modifications in knockout cells. Finally, we found that m6A regulates histone modification in part by destabilizing transcripts that encode histone-modifying enzymes. Our results suggest an essential role for m6A in development and reveal m6A-regulated histone modifications as a previously unknown mechanism of gene regulation in mammalian cells.
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Affiliation(s)
- Yang Wang
- Tumor Initiation and Maintenance Program, NCI-designated Cancer Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, USA
| | - Yue Li
- Computer Science and Artificial Intelligence Laboratory, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Minghui Yue
- Division of Reproductive Sciences, Division of Developmental Biology, Perinatal Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
- Department of Pediatrics, University of Cincinnati, Cincinnati, OH, USA
| | - Jun Wang
- Tumor Initiation and Maintenance Program, NCI-designated Cancer Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, USA
| | - Sandeep Kumar
- Development, Aging, and Regeneration Program, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, USA
| | - Robert J Wechsler-Reya
- Tumor Initiation and Maintenance Program, NCI-designated Cancer Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, USA
| | - Zhaolei Zhang
- Department of Molecular Genetics, The Donnelly Centre, University of Toronto, Toronto, Ontario, Canada
| | - Yuya Ogawa
- Division of Reproductive Sciences, Division of Developmental Biology, Perinatal Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
- Department of Pediatrics, University of Cincinnati, Cincinnati, OH, USA
| | - Manolis Kellis
- Computer Science and Artificial Intelligence Laboratory, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Gregg Duester
- Development, Aging, and Regeneration Program, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, USA
| | - Jing Crystal Zhao
- Tumor Initiation and Maintenance Program, NCI-designated Cancer Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, CA, USA.
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Saha P, Verma S, Pathak RU, Mishra RK. Long Noncoding RNAs in Mammalian Development and Diseases. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018; 1008:155-198. [PMID: 28815540 DOI: 10.1007/978-981-10-5203-3_6] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Following analysis of sequenced genomes and transcriptome of many eukaryotes, it is evident that virtually all protein-coding genes have already been discovered. These advances have highlighted an intriguing paradox whereby the relative amount of protein-coding sequences remain constant but nonprotein-coding sequences increase consistently in parallel to increasing evolutionary complexity. It is established that differences between species map to nonprotein-coding regions of the genome that surprisingly is transcribed extensively. These transcripts regulate epigenetic processes and constitute an important layer of regulatory information essential for organismal development and play a causative role in diseases. The noncoding RNA-directed regulatory circuit controls complex characteristics. Sequence variations in noncoding RNAs influence evolution, quantitative traits, and disease susceptibility. This chapter presents an account on a class of such noncoding transcripts that are longer than 200 nucleotides (long noncoding RNA-lncRNA) in mammalian development and diseases.
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Affiliation(s)
- Parna Saha
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad, 500007, India
| | - Shreekant Verma
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad, 500007, India
| | - Rashmi U Pathak
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad, 500007, India.
| | - Rakesh K Mishra
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad, 500007, India.
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28
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Patterson B, Tanaka Y, Park IH. New Advances in Human X chromosome status from a Developmental and Stem Cell Biology. Tissue Eng Regen Med 2017; 14:643-652. [PMID: 29276809 PMCID: PMC5738034 DOI: 10.1007/s13770-017-0096-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Revised: 10/16/2017] [Accepted: 11/03/2017] [Indexed: 11/26/2022] Open
Abstract
Recent advances in stem cell biology have dramatically increased the understanding of molecular and cellular mechanism of pluripotency and cell fate determination. Additionally, pluripotent stem cells (PSCs), including embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs), arose as essential resources for disease modeling and cellular therapeutics. Despite these advancements, the epigenetic dysregulation in pluripotency such as the imprinting status, and X chromosome dosage compensation, and its consequences on future utility of PSCs yet remain unresolved. In this review, we will focus on the X chromosome regulation in human PSCs (hPSCs). We will introduce the previous findings in the dosage compensation process on mouse model, and make comparison with those of human systems. Particularly, the biallelic X chromosome activation status of human preimplantation embryos, and the regulation of the active X chromosome by human specific lincRNA, XACT, will be discussed. We will also discuss the recent findings on higher order X chromosome architecture utilizing Hi-C, and abnormal X chromosome status in hPSCs.
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Affiliation(s)
- Benjamin Patterson
- Department of Genetics, Yale Stem Cell Center, Yale School of Medicine, New Haven, CT 06520 USA
| | - Yoshiaki Tanaka
- Department of Genetics, Yale Stem Cell Center, Yale School of Medicine, New Haven, CT 06520 USA
| | - In-Hyun Park
- Department of Genetics, Yale Stem Cell Center, Yale School of Medicine, New Haven, CT 06520 USA
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29
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Abstract
Extensive 3D folding is required to package a genome into the tiny nuclear space, and this packaging must be compatible with proper gene expression. Thus, in the well-hierarchized nucleus, chromosomes occupy discrete territories and adopt specific 3D organizational structures that facilitate interactions between regulatory elements for gene expression. The mammalian X chromosome exemplifies this structure-function relationship. Recent studies have shown that, upon X-chromosome inactivation, active and inactive X chromosomes localize to different subnuclear positions and adopt distinct chromosomal architectures that reflect their activity states. Here, we review the roles of long non-coding RNAs, chromosomal organizational structures and the subnuclear localization of chromosomes as they relate to X-linked gene expression.
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30
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Xist and Tsix Transcription Dynamics Is Regulated by the X-to-Autosome Ratio and Semistable Transcriptional States. Mol Cell Biol 2016; 36:2656-2667. [PMID: 27528619 PMCID: PMC5064214 DOI: 10.1128/mcb.00183-16] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2016] [Accepted: 07/20/2016] [Indexed: 12/15/2022] Open
Abstract
In female mammals, X chromosome inactivation (XCI) is a key process in the control of gene dosage compensation between X-linked genes and autosomes. Xist and Tsix, two overlapping antisense-transcribed noncoding genes, are central elements of the X inactivation center (Xic) regulating XCI. Xist upregulation results in the coating of the entire X chromosome by Xist RNA in cis, whereas Tsix transcription acts as a negative regulator of Xist. Here, we generated Xist and Tsix reporter mouse embryonic stem (ES) cell lines to study the genetic and dynamic regulation of these genes upon differentiation. Our results revealed mutually antagonistic roles for Tsix on Xist and vice versa and indicate the presence of semistable transcriptional states of the Xic locus predicting the outcome of XCI. These transcriptional states are instructed by the X-to-autosome ratio, directed by regulators of XCI, and can be modulated by tissue culture conditions.
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31
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Li C, Hong T, Webb CH, Karner H, Sun S, Nie Q. A self-enhanced transport mechanism through long noncoding RNAs for X chromosome inactivation. Sci Rep 2016; 6:31517. [PMID: 27527711 PMCID: PMC4985753 DOI: 10.1038/srep31517] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2016] [Accepted: 07/21/2016] [Indexed: 11/09/2022] Open
Abstract
X-chromosome inactivation (XCI) is the mammalian dosage compensation strategy for balancing sex chromosome content between females and males. While works exist on initiation of symmetric breaking, the underlying allelic choice mechanisms and dynamic regulation responsible for the asymmetric fate determination of XCI remain elusive. Here we combine mathematical modeling and experimental data to examine the mechanism of XCI fate decision by analyzing the signaling regulatory circuit associated with long noncoding RNAs (lncRNAs) involved in XCI. We describe three plausible gene network models that incorporate features of lncRNAs in their localized actions and rapid transcriptional turnovers. In particular, we show experimentally that Jpx (a lncRNA) is transcribed biallelically, escapes XCI, and is asymmetrically dispersed between two X's. Subjecting Jpx to our test of model predictions against previous experimental observations, we identify that a self-enhanced transport feedback mechanism is critical to XCI fate decision. In addition, the analysis indicates that an ultrasensitive response of Jpx signal on CTCF is important in this mechanism. Overall, our combined modeling and experimental data suggest that the self-enhanced transport regulation based on allele-specific nature of lncRNAs and their temporal dynamics provides a robust and novel mechanism for bi-directional fate decisions in critical developmental processes.
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Affiliation(s)
- Chunhe Li
- Department of Mathematics, University of California, Irvine, Irvine, CA 92697, USA
- Center for Complex Biological Systems, University of California, Irvine, Irvine, CA 92697, USA
| | - Tian Hong
- Department of Mathematics, University of California, Irvine, Irvine, CA 92697, USA
- Center for Complex Biological Systems, University of California, Irvine, Irvine, CA 92697, USA
| | - Chiu-Ho Webb
- Department of Developmental and Cell Biology, University of California, Irvine, Irvine, CA 92697, USA
| | - Heather Karner
- Department of Developmental and Cell Biology, University of California, Irvine, Irvine, CA 92697, USA
| | - Sha Sun
- Center for Complex Biological Systems, University of California, Irvine, Irvine, CA 92697, USA
- Department of Developmental and Cell Biology, University of California, Irvine, Irvine, CA 92697, USA
| | - Qing Nie
- Department of Mathematics, University of California, Irvine, Irvine, CA 92697, USA
- Center for Complex Biological Systems, University of California, Irvine, Irvine, CA 92697, USA
- Department of Developmental and Cell Biology, University of California, Irvine, Irvine, CA 92697, USA
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32
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Thoughts about SLC16A2, TSIX and XIST gene like sites in the human genome and a potential role in cellular chromosome counting. Mol Cytogenet 2016; 9:56. [PMID: 27504142 PMCID: PMC4976476 DOI: 10.1186/s13039-016-0271-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Accepted: 07/25/2016] [Indexed: 12/12/2022] Open
Abstract
Background Chromosome counting is a process in which cells determine somehow their intrinsic chromosome number(s). The best-studied cellular mechanism that involves chromosome counting is ‘chromosome-kissing’ and X-chromosome inactivation (XCI) mechanism. It is necessary for the well-known dosage compensation between the genders in mammals to balance the number of active X-chromosomes (Xa) with regard to diploid set of autosomes. At the onset of XCI, two X-chromosomes are coming in close proximity and pair physically by a specific segment denominated X-pairing region (Xpr) that involves the SLC16A2 gene. Results An Ensembl BLAST search for human and mouse SLC16A2/Slc16a2 homologues revealed, that highly similar sequences can be found at almost each chromosome in the corresponding genomes. Additionally, a BLAST search for SLC16A2/TSIX/XIST (genes responsible for XCI) reveled that “SLC16A2/TSIX/XIST like sequences” cover equally all chromosomes, too. With respect to this we provide following hypotheses. Hypotheses If a single genomic region containing the SLC16A2 gene on X-chromosome is responsible for maintaining “balanced” active copy numbers, it is possible that similar sequences or gene/s have the same function on other chromosomes (autosomes). SLC16A2 like sequences on autosomes could encompass evolutionary older, but functionally active key regions for chromosome counting in early embryogenesis. Also SLC16A2 like sequence on autosomes could be involved in inappropriate chromosomes pairing and, thereby be involved in aneuploidy formation during embryogenesis and cancer development. Also, “SLC16A2/TSIX/XIST gene like sequence combinations” covering the whole genome, could be important for the determination of X:autosome ratio in cells and chromosome counting. Conclusions SLC16A2 and/or SLC16A2/TSIX/XIST like sequence dispersed across autosomes and X-chromosome(s) could serve as bases for a counting mechanism to determine X:autosome ratio and could potentially be a mechanism by which a cell also counts its autosomes. It could also be that such specific genomic regions have the same function for each specific autosome. As errors during the obviously existing process of chromosome counting are one if not the major origin of germline/somatic aneuploidy the here presented hypotheses should further elaborated and experimentally tested. Electronic supplementary material The online version of this article (doi:10.1186/s13039-016-0271-7) contains supplementary material, which is available to authorized users.
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Vallot C, Ouimette JF, Rougeulle C. Establishment of X chromosome inactivation and epigenomic features of the inactive X depend on cellular contexts. Bioessays 2016; 38:869-80. [PMID: 27389958 DOI: 10.1002/bies.201600121] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
X chromosome inactivation (XCI) is an essential epigenetic process that ensures X-linked gene dosage equilibrium between sexes in mammals. XCI is dynamically regulated during development in a manner that is intimately linked to differentiation. Numerous studies, which we review here, have explored the dynamics of X inactivation and reactivation in the context of development, differentiation and diseases, and the phenotypic and molecular link between the inactive status, and the cellular context. Here, we also assess whether XCI is a uniform mechanism in mammals by analyzing epigenetic signatures of the inactive X (Xi) in different species and cellular contexts. It appears that the timing of XCI and the epigenetic signature of the inactive X greatly vary between species. Surprisingly, even within a given species, various Xi configurations are found across cellular states. We discuss possible mechanisms underlying these variations, and how they might influence the fate of the Xi.
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Affiliation(s)
- Céline Vallot
- Sorbonne Paris Cité, Epigenetics and Cell Fate, Université Paris Diderot, Paris, France
| | | | - Claire Rougeulle
- Sorbonne Paris Cité, Epigenetics and Cell Fate, Université Paris Diderot, Paris, France
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34
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Furlan G, Rougeulle C. Function and evolution of the long noncoding RNA circuitry orchestrating X-chromosome inactivation in mammals. WILEY INTERDISCIPLINARY REVIEWS-RNA 2016; 7:702-22. [PMID: 27173581 DOI: 10.1002/wrna.1359] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2015] [Revised: 03/30/2016] [Accepted: 03/31/2016] [Indexed: 12/20/2022]
Abstract
X-chromosome inactivation (XCI) is a chromosome-wide regulatory process that ensures dosage compensation for X-linked genes in Theria. XCI is established during early embryogenesis and is developmentally regulated. Different XCI strategies exist in mammalian infraclasses and the regulation of this process varies also among closely related species. In Eutheria, initiation of XCI is orchestrated by a cis-acting locus, the X-inactivation center (Xic), which is particularly enriched in genes producing long noncoding RNAs (lncRNAs). Among these, Xist generates a master transcript that coats and propagates along the future inactive X-chromosome in cis, establishing X-chromosome wide transcriptional repression through interaction with several protein partners. Other lncRNAs also participate to the regulation of X-inactivation but the extent to which their function has been maintained in evolution is still poorly understood. In Metatheria, Xist is not conserved, but another, evolutionary independent lncRNA with similar properties, Rsx, has been identified, suggesting that lncRNA-mediated XCI represents an evolutionary advantage. Here, we review current knowledge on the interplay of X chromosome-encoded lncRNAs in ensuring proper establishment and maintenance of chromosome-wide silencing, and discuss the evolutionary implications of the emergence of species-specific lncRNAs in the control of XCI within Theria. WIREs RNA 2016, 7:702-722. doi: 10.1002/wrna.1359 For further resources related to this article, please visit the WIREs website.
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Affiliation(s)
- Giulia Furlan
- Sorbonne Paris Cité, Epigenetics and Cell Fate, UMR7216 CNRS, Université Paris Diderot, Paris, France
| | - Claire Rougeulle
- Sorbonne Paris Cité, Epigenetics and Cell Fate, UMR7216 CNRS, Université Paris Diderot, Paris, France
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35
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Payer B. Developmental regulation of X-chromosome inactivation. Semin Cell Dev Biol 2016; 56:88-99. [PMID: 27112543 DOI: 10.1016/j.semcdb.2016.04.014] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Revised: 04/13/2016] [Accepted: 04/21/2016] [Indexed: 12/01/2022]
Abstract
With the emergence of sex-determination by sex chromosomes, which differ in composition and number between males and females, appeared the need to equalize X-chromosomal gene dosage between the sexes. Mammals have devised the strategy of X-chromosome inactivation (XCI), in which one of the two X-chromosomes is rendered transcriptionally silent in females. In the mouse, the best-studied model organism with respect to XCI, this inactivation process occurs in different forms, imprinted and random, interspersed by periods of X-chromosome reactivation (XCR), which is needed to switch between the different modes of XCI. In this review, I describe the recent advances with respect to the developmental control of XCI and XCR and in particular their link to differentiation and pluripotency. Furthermore, I review the mechanisms, which influence the timing and choice, with which one of the two X-chromosomes is chosen for inactivation during random XCI. This has an impact on how females are mosaics with regard to which X-chromosome is active in different cells, which has implications on the severity of diseases caused by X-linked mutations.
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Affiliation(s)
- Bernhard Payer
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology and Universitat Pompeu Fabra (UPF), Dr. Aiguader, 88, Barcelona 08003, Spain.
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36
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LAKHOTIA SUBHASHC. Divergent actions of long noncoding RNAs on X-chromosome remodelling in mammals and Drosophila achieve the same end result: dosage compensation. J Genet 2015; 94:575-84. [DOI: 10.1007/s12041-015-0566-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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37
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A pathophysiological view of the long non-coding RNA world. Oncotarget 2015; 5:10976-96. [PMID: 25428918 PMCID: PMC4294373 DOI: 10.18632/oncotarget.2770] [Citation(s) in RCA: 142] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2014] [Accepted: 11/14/2014] [Indexed: 12/13/2022] Open
Abstract
Because cells are constantly exposed to micro-environmental changes, they require the ability to adapt to maintain a dynamic equilibrium. Proteins are considered critical for the regulation of gene expression, which is a fundamental process in determining the cellular responses to stimuli. Recently, revolutionary findings in RNA research and the advent of high-throughput genomic technologies have revealed a pervasive transcription of the human genome, which generates many long non-coding RNAs (lncRNAs) whose roles are largely undefined. However, there is evidence that lncRNAs are involved in several cellular physiological processes such as adaptation to stresses, cell differentiation, maintenance of pluripotency and apoptosis. The correct balance of lncRNA levels is crucial for the maintenance of cellular equilibrium, and the dysregulation of lncRNA expression is linked to many disorders; certain transcripts are useful prognostic markers for some of these pathologies. This review revisits the classic concept of cellular homeostasis from the perspective of lncRNAs specifically to understand how this novel class of molecules contributes to cellular balance and how its dysregulated expression can lead to the onset of pathologies such as cancer.
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38
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Hwang JY, Choi KH, Lee DK, Kim SH, Kim EB, Hyun SH, Lee CK. Overexpression of OCT4A ortholog elevates endogenous XIST in porcine parthenogenic blastocysts. J Reprod Dev 2015; 61:533-40. [PMID: 26255835 PMCID: PMC4685219 DOI: 10.1262/jrd.2015-017] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
X-chromosome inactivation (XCI) is an epigenetic process that equalizes expression of X-borne genes between
male and female eutherians. This process is observed in early eutherian embryo development in a
species-specific manner. Until recently, various pluripotent factors have been suggested to regulate the
process of XCI by repressing XIST expression, which is the master inducer for XCI. Recent
insights into the process and its regulation have been restricted in mouse species despite the evolutionary
diversity of the process and molecular mechanism among the species. OCT4A is one of the
represented pluripotent factors, the gate-keeper for maintaining pluripotency, and an XIST
repressor. Therefore, in here, we examined the relation between OCT4A and X-linked genes in
porcine preimplantation embryos. Three X-linked genes, XIST,
LOC102165544, and RLIM, were selected in present study because their
orthologues have been known to regulate XCI in mice. Expression levels of OCT4A were
positively correlated with XIST and LOC102165544 in female blastocysts.
Furthermore, overexpression of exogenous human OCT4A in cleaved parthenotes generated
blastocysts with increased XIST expression levels. However, increased XIST
expression was not observed when exogenous OCT4A was obtained from early blastocysts. These
results suggest the possibility that OCT4A would be directly or indirectly involved in
XIST expression in earlier stage porcine embryos rather than blastocysts.
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Affiliation(s)
- Jae Yeon Hwang
- Department of Agricultural Biotechnology, Animal Biotechnology Major, and Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul 151-921, Republic of Korea
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Yue M, Charles Richard JL, Ogawa Y. Dynamic interplay and function of multiple noncoding genes governing X chromosome inactivation. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2015; 1859:112-20. [PMID: 26260844 DOI: 10.1016/j.bbagrm.2015.07.015] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Revised: 07/07/2015] [Accepted: 07/14/2015] [Indexed: 12/17/2022]
Abstract
There is increasing evidence for the emergence of long noncoding RNAs (lncRNAs) as important components, especially in the regulation of gene expression. In the event of X chromosome inactivation, robust epigenetic marks are established in a long noncoding Xist RNA-dependent manner, giving rise to a distinct epigenetic landscape on the inactive X chromosome (Xi). The X inactivation center (Xic) is essential for induction of X chromosome inactivation and harbors two topologically associated domains (TADs) to regulate monoallelic Xist expression: one at the noncoding Xist gene and its upstream region, and the other at the antisense Tsix and its upstream region. The monoallelic expression of Xist is tightly regulated by these two functionally distinct TADs as well as their constituting lncRNAs and proteins. In this review, we summarize recent updates in our knowledge of lncRNAs found at the Xic and discuss their overall mechanisms of action. We also discuss our current understanding of the molecular mechanism behind Xist RNA-mediated induction of the repressive epigenetic landscape at the Xi. This article is part of a Special Issue entitled: Clues to long noncoding RNA taxonomy1, edited by Dr. Tetsuro Hirose and Dr. Shinichi Nakagawa.
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Affiliation(s)
- Minghui Yue
- Division of Reproductive Sciences, Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue, Cincinnati, OH 45229, USA; Department of Pediatrics, University of Cincinnati College of Medicine, 3333 Burnet Avenue, Cincinnati, OH 45229, USA
| | - John Lalith Charles Richard
- Division of Reproductive Sciences, Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue, Cincinnati, OH 45229, USA; Department of Pediatrics, University of Cincinnati College of Medicine, 3333 Burnet Avenue, Cincinnati, OH 45229, USA
| | - Yuya Ogawa
- Division of Reproductive Sciences, Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue, Cincinnati, OH 45229, USA; Department of Pediatrics, University of Cincinnati College of Medicine, 3333 Burnet Avenue, Cincinnati, OH 45229, USA.
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40
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Xist Exon 7 Contributes to the Stable Localization of Xist RNA on the Inactive X-Chromosome. PLoS Genet 2015; 11:e1005430. [PMID: 26244333 PMCID: PMC4526699 DOI: 10.1371/journal.pgen.1005430] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2015] [Accepted: 07/06/2015] [Indexed: 01/09/2023] Open
Abstract
To equalize X-linked gene dosage between the sexes in mammalian females, Xist RNA inactivates one of the two X-chromosomes. Here, we report the crucial function of Xist exon 7 in X-inactivation. Xist exon 7 is the second-largest exon with a well-conserved repeat E in eutherian mammals, but its role is often overlooked in X-inactivation. Although female ES cells with a targeted truncation of the Xist exon 7 showed no significant differences in their Xist expression levels and RNA stability from control cells expressing wild-type Xist, compromised localization of Xist RNA and incomplete silencing of X-linked genes on the inactive X-chromosome (Xi) were observed in the exon 7-truncated mutant cells. Furthermore, the interaction between the mutant Xist RNA and hnRNP U required for localization of Xist RNA to the Xi was impaired in the Xist exon 7 truncation mutant cells. Our results suggest that exon 7 of Xist RNA plays an important role for stable Xist RNA localization and silencing of the X-linked genes on the Xi, possibly acting through an interaction with hnRNP U. To balance gene expression from X-chromosomes between males and females, one of the two X-chromosomes is inactivated in female mammals. X-chromosome inactivation is a chromosome-wide epigenetic gene silencing mechanism regulated by long non-coding Xist RNA. Mouse Xist RNA is commonly organized into 7 exons, with the extensively studied and known important domains of Xist residing within exon 1. However, the function of exon 7 of Xist RNA, which is the second longest exon, remains poorly understood. Our objective was to clarify the role of this exon in X-inactivation through the use of Xist truncation mutant female ES cells. Here, we provide evidence that Xist exon 7 is required for the stable localization of Xist RNA and X-linked gene silencing on the inactive X-chromosome.
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41
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Abstract
Female mammalian cells compensate dosage of X-linked gene expression through the inactivation of one of their two X chromosomes. X chromosome inactivation (XCI) in eutherians is dependent on the non-coding RNA Xist that is up-regulated from the future inactive X chromosome, coating it and recruiting factors involved in silencing and altering its chromatin state. Xist lies within the X-inactivation center (Xic), a region on the X that is required for XCI, and is regulated in cis by elements on the X chromosome and in trans by diffusible factors. In this review, we summarize the latest results in cis- and trans-regulation of the Xic. We discuss how the organization of the Xic in topologically associating domains is important for XCI (cis-regulation) and how proteins in the pluripotent state and upon development or differentiation of embryonic stem cells control proper inactivation of one X chromosome (trans-regulation).
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42
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Massah S, Beischlag TV, Prefontaine GG. Epigenetic events regulating monoallelic gene expression. Crit Rev Biochem Mol Biol 2015; 50:337-58. [PMID: 26155735 DOI: 10.3109/10409238.2015.1064350] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
In mammals, generally it is assumed that the genes inherited from each parent are expressed to similar levels. However, it is now apparent that in non-sex chromosomes, 6-10% of genes are selected for monoallelic expression. Monoallelic expression or allelic exclusion is established either in an imprinted (parent-of-origin) or a stochastic manner. The stochastic model explains random selection while the imprinted model describes parent-of-origin specific selection of alleles for expression. Allelic exclusion occurs during X chromosome inactivation, parent-of-origin expression of imprinted genes and stochastic monoallelic expression of cell surface molecules, clustered protocadherin (PCDH) genes. Mis-regulation or loss of allelic exclusion contributes to developmental diseases. Epigenetic mechanisms are fundamental players that determine this type of expression despite a homogenous genetic background. DNA methylation and histone modifications are two mediators of the epigenetic phenomena. The majority of DNA methylation is found on cytosines of the CpG dinucleotide in mammals. Several covalent modifications of histones change the electrostatic forces between DNA and histones modifying gene expression. Long-range chromatin interactions organize chromatin into transcriptionally permissive and prohibitive regions leading to simultaneous regulation of gene expression and repression. Non-coding RNAs (ncRNAs) are also players in regulating gene expression. Together, these epigenetic mechanisms fine-tune gene expression levels essential for normal development and survival. In this review, first we discuss what is known about monoallelic gene expression. Then, we focus on the molecular mechanisms that regulate expression of three monoallelically expressed gene classes: the X-linked genes, selected imprinted genes and PCDH genes.
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Affiliation(s)
- Shabnam Massah
- a The Faculty of Health Sciences , Simon Fraser University , Burnaby , BC , Canada
| | - Timothy V Beischlag
- a The Faculty of Health Sciences , Simon Fraser University , Burnaby , BC , Canada
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43
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Zhou HY, Katsman Y, Dhaliwal NK, Davidson S, Macpherson NN, Sakthidevi M, Collura F, Mitchell JA. A Sox2 distal enhancer cluster regulates embryonic stem cell differentiation potential. Genes Dev 2015; 28:2699-711. [PMID: 25512558 PMCID: PMC4265674 DOI: 10.1101/gad.248526.114] [Citation(s) in RCA: 116] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The Sox2 transcription factor must be robustly transcribed in embryonic stem (ES) cells to maintain pluripotency. Zhou et al. identify three novel enhancers that, through the formation of chromatin loops, form a chromatin complex with the Sox2 promoter in ES cells. The distal cluster containing SRR107 and SRR111, located >100 kb downstream from Sox2, is required for cis-regulation of Sox2 in ES cells. The Sox2 transcription factor must be robustly transcribed in embryonic stem (ES) cells to maintain pluripotency. Two gene-proximal enhancers, Sox2 regulatory region 1 (SRR1) and SRR2, display activity in reporter assays, but deleting SRR1 has no effect on pluripotency. We identified and functionally validated the sequences required for Sox2 transcription based on a computational model that predicted transcriptional enhancer elements within 130 kb of Sox2. Our reporter assays revealed three novel enhancers—SRR18, SRR107, and SRR111—that, through the formation of chromatin loops, form a chromatin complex with the Sox2 promoter in ES cells. Using the CRISPR/Cas9 system and F1 ES cells (Mus musculus129 × Mus castaneus), we generated heterozygous deletions of each enhancer region, revealing that only the distal cluster containing SRR107 and SRR111, located >100 kb downstream from Sox2, is required for cis-regulation of Sox2 in ES cells. Furthermore, homozygous deletion of this distal Sox2 control region (SCR) caused significant reduction in Sox2 mRNA and protein levels, loss of ES cell colony morphology, genome-wide changes in gene expression, and impaired neuroectodermal formation upon spontaneous differentiation to embryoid bodies. Together, these data identify a distal control region essential for Sox2 transcription in ES cells.
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Affiliation(s)
- Harry Y Zhou
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario M5S 3G5, Canada
| | - Yulia Katsman
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario M5S 3G5, Canada
| | - Navroop K Dhaliwal
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario M5S 3G5, Canada
| | - Scott Davidson
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario M5S 3G5, Canada
| | - Neil N Macpherson
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario M5S 3G5, Canada
| | - Moorthy Sakthidevi
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario M5S 3G5, Canada
| | - Felicia Collura
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario M5S 3G5, Canada
| | - Jennifer A Mitchell
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario M5S 3G5, Canada; Center for the Analysis of Genome Evolution and Function, University of Toronto, Toronto, Ontario M5S 3G5, Canada
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44
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Kung JT, Kesner B, An JY, Ahn JY, Cifuentes-Rojas C, Colognori D, Jeon Y, Szanto A, del Rosario BC, Pinter SF, Erwin JA, Lee JT. Locus-specific targeting to the X chromosome revealed by the RNA interactome of CTCF. Mol Cell 2015; 57:361-75. [PMID: 25578877 PMCID: PMC4316200 DOI: 10.1016/j.molcel.2014.12.006] [Citation(s) in RCA: 130] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2014] [Revised: 10/28/2014] [Accepted: 11/25/2014] [Indexed: 12/27/2022]
Abstract
CTCF is a master regulator that plays important roles in genome architecture and gene expression. How CTCF is recruited in a locus-specific manner is not fully understood. Evidence from epigenetic processes, such as X chromosome inactivation (XCI), indicates that CTCF associates functionally with RNA. Using genome-wide approaches to investigate the relationship between its RNA interactome and epigenomic landscape, here we report that CTCF binds thousands of transcripts in mouse embryonic stem cells, many in close proximity to CTCF's genomic binding sites. CTCF is a specific and high-affinity RNA-binding protein (Kd < 1 nM). During XCI, CTCF differentially binds the active and inactive X chromosomes and interacts directly with Tsix, Xite, and Xist RNAs. Tsix and Xite RNAs target CTCF to the X inactivation center, thereby inducing homologous X chromosome pairing. Our work elucidates one mechanism by which CTCF is recruited in a locus-specific manner and implicates CTCF-RNA interactions in long-range chromosomal interactions.
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Affiliation(s)
- Johnny T Kung
- Howard Hughes Medical Institute; Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114 USA; Department of Genetics, Harvard Medical School, Boston, MA 02115 USA
| | - Barry Kesner
- Howard Hughes Medical Institute; Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114 USA; Department of Genetics, Harvard Medical School, Boston, MA 02115 USA
| | - Jee Young An
- Howard Hughes Medical Institute; Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114 USA; Department of Genetics, Harvard Medical School, Boston, MA 02115 USA
| | - Janice Y Ahn
- Howard Hughes Medical Institute; Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114 USA; Department of Genetics, Harvard Medical School, Boston, MA 02115 USA; Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138 USA
| | - Catherine Cifuentes-Rojas
- Howard Hughes Medical Institute; Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114 USA; Department of Genetics, Harvard Medical School, Boston, MA 02115 USA
| | - David Colognori
- Howard Hughes Medical Institute; Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114 USA; Department of Genetics, Harvard Medical School, Boston, MA 02115 USA
| | - Yesu Jeon
- Howard Hughes Medical Institute; Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114 USA; Department of Genetics, Harvard Medical School, Boston, MA 02115 USA
| | - Attila Szanto
- Howard Hughes Medical Institute; Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114 USA; Department of Genetics, Harvard Medical School, Boston, MA 02115 USA
| | - Brian C del Rosario
- Howard Hughes Medical Institute; Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114 USA; Department of Genetics, Harvard Medical School, Boston, MA 02115 USA
| | - Stefan F Pinter
- Howard Hughes Medical Institute; Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114 USA; Department of Genetics, Harvard Medical School, Boston, MA 02115 USA
| | - Jennifer A Erwin
- Howard Hughes Medical Institute; Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114 USA; Department of Genetics, Harvard Medical School, Boston, MA 02115 USA
| | - Jeannie T Lee
- Howard Hughes Medical Institute; Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114 USA; Department of Genetics, Harvard Medical School, Boston, MA 02115 USA; Department of Pathology, Massachusetts General Hospital, Boston, MA 02114 USA.
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Richard JLC, Ogawa Y. Understanding the Complex Circuitry of lncRNAs at the X-inactivation Center and Its Implications in Disease Conditions. Curr Top Microbiol Immunol 2015; 394:1-27. [PMID: 25982976 DOI: 10.1007/82_2015_443] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Balanced gene expression is a high priority in order to maintain optimal functioning since alterations and variations could result in acute consequences. X chromosome inactivation (X-inactivation) is one such strategy utilized by mammalian species to silence the extra X chromosome in females to uphold a similar level of expression between the two sexes. A functionally versatile class of molecules called long noncoding RNA (lncRNA) has emerged as key regulators of gene expression and plays important roles during development. An lncRNA that is indispensable for X-inactivation is X-inactive specific transcript (Xist), which induces a repressive epigenetic landscape and creates the inactive X chromosome (Xi). With recent advents in the field of X-inactivation, novel positive and negative lncRNA regulators of Xist such as Jpx and Tsix, respectively, have broadened the regulatory network of X-inactivation. Xist expression failure or dysregulation has been implicated in producing developmental anomalies and disease states. Subsequently, reactivation of the Xi at a later stage of development has also been associated with certain tumors. With the recent influx of information about lncRNA biology and advancements in methods to probe lncRNA, we can now attempt to understand this complex network of Xist regulation in development and disease. It has become clear that the presence of an extra set of genes could be fatal for the organism. Only by understanding the precise ways in which lncRNAs function can treatments be developed to bring aberrations under control. This chapter summarizes our current understanding and knowledge with regard to how lncRNAs are orchestrated at the X-inactivation center (Xic), with a special focus on how genetic diseases come about as a consequence of lncRNA dysregulation.
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Affiliation(s)
- John Lalith Charles Richard
- Division of Reproductive Sciences, Cincinnati Children's Hospital Medical Center; Department of Pediatrics, University of Cincinnati College of Medicine, 3333 Burnet Avenue, Cincinnati, OH, 45229, USA
| | - Yuya Ogawa
- Division of Reproductive Sciences, Cincinnati Children's Hospital Medical Center; Department of Pediatrics, University of Cincinnati College of Medicine, 3333 Burnet Avenue, Cincinnati, OH, 45229, USA.
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46
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Chen LL, Zhao JC. Functional analysis of long noncoding RNAs in development and disease. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2014; 825:129-58. [PMID: 25201105 DOI: 10.1007/978-1-4939-1221-6_4] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Once viewed as part of the "dark matter" of genome, long noncoding RNAs (lncRNAs), which are mRNA-like but lack open reading frames, have emerged as an integral part of the mammalian transcriptome. Recent work demonstrated that lncRNAs play multiple structural and functional roles, and their analysis has become a new frontier in biomedical research. In this chapter, we provide an overview of different lncRNA families, describe methodologies available to study lncRNA-protein and lncRNA-DNA interactions systematically, and use well-studied lncRNAs as examples to illustrate their functional importance during normal development and in disease states.
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Affiliation(s)
- Ling-Ling Chen
- State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, 200031, China,
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47
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Kota SK, Roy Chowdhury D, Rao LK, Padmalatha V, Singh L, Bhadra U. Uncoupling of X-linked gene silencing from XIST binding by DICER1 and chromatin modulation on human inactive X chromosome. Chromosoma 2014; 124:249-62. [PMID: 25428210 DOI: 10.1007/s00412-014-0495-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2014] [Revised: 10/24/2014] [Accepted: 11/07/2014] [Indexed: 12/18/2022]
Abstract
In mammals, X-inactivation process is achieved by the cis-spreading of long noncoding Xist RNA over one of the female X chromosomes. The Xist binding accumulates histones H3 methylation and H4 hypoacetylation required for X inactivation that leads to proper dosage compensation of the X-linked genes. Co-transcription of Tsix, an antisense copy of Xist, blocks the Xist coating on the Xi. In mice ES cells, an RNase III enzyme Dicer1 disrupts Xist binding and methylated H3K27me3 accumulation on the Xi. Later, multiple reports opposed these findings raising a question regarding the possible role of Dicer1 in murine X silencing. Here, we show that reduction of DICER1 in human female cells increases XIST transcripts without compromising the binding of the XIST and histone tail modifications on the Xi. Moreover, DICER1-depleted cells show differential upregulation of many human X-linked genes by binding different amounts of acetylated histone predominantly on their active promoter sites. Therefore, X-linked gene silencing, which is thought to be coupled with the accumulation of XIST and heterochromatin markers on Xi can be disrupted in DICER1 depleted human cells. These results suggest that DICER1 has no apparent effect on the recruitment of heterochromatic markers on the Xi but is required for inactivation of differentially regulated genes for the maintenance of proper dosage compensation in differentiated cells.
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Affiliation(s)
- Satya Keerthi Kota
- Functional Genomics and Gene Silencing Group, Centre For Cellular and Molecular Biology, Uppal Road, Hyderabad, 500 007, India
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48
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Yue M, Charles Richard JL, Yamada N, Ogawa A, Ogawa Y. Quick fluorescent in situ hybridization protocol for Xist RNA combined with immunofluorescence of histone modification in X-chromosome inactivation. J Vis Exp 2014:e52053. [PMID: 25489864 DOI: 10.3791/52053] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Combining RNA fluorescent in situ hybridization (FISH) with immunofluorescence (immuno-FISH) creates a technique that can be employed at the single cell level to detect the spatial dynamics of RNA localization with simultaneous insight into the localization of proteins, epigenetic modifications and other details which can be highlighted by immunofluorescence. X-chromosome inactivation is a paradigm for long non-coding RNA (lncRNA)-mediated gene silencing. X-inactive specific transcript (Xist) lncRNA accumulation (called an Xist cloud) on one of the two X-chromosomes in mammalian females is a critical step to initiate X-chromosome inactivation. Xist RNA directly or indirectly interacts with various chromatin-modifying enzymes and introduces distinct epigenetic landscapes to the inactive X-chromosome (Xi). One known epigenetic hallmark of the Xi is the Histone H3 trimethyl-lysine 27 (H3K27me3) modification. Here, we describe a simple and quick immuno-FISH protocol for detecting Xist RNA using RNA FISH with multiple oligonucleotide probes coupled with immunofluorescence of H3K27me3 to examine the localization of Xist RNA and associated epigenetic modifications. Using oligonucleotide probes results in a shorter incubation time and more sensitive detection of Xist RNA compared to in vitro transcribed RNA probes (riboprobes). This protocol provides a powerful tool for understanding the dynamics of lncRNAs and its associated epigenetic modification, chromatin structure, nuclear organization and transcriptional regulation.
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Affiliation(s)
- Minghui Yue
- Division of Reproductive Sciences, Cincinnati Children's Hospital Medical Center; Department of Pediatrics, University of Cincinnati College of Medicine
| | - John Lalith Charles Richard
- Division of Reproductive Sciences, Cincinnati Children's Hospital Medical Center; Department of Pediatrics, University of Cincinnati College of Medicine
| | - Norishige Yamada
- Division of Reproductive Sciences, Cincinnati Children's Hospital Medical Center; Department of Pediatrics, University of Cincinnati College of Medicine
| | - Akiyo Ogawa
- Division of Reproductive Sciences, Cincinnati Children's Hospital Medical Center
| | - Yuya Ogawa
- Division of Reproductive Sciences, Cincinnati Children's Hospital Medical Center; Department of Pediatrics, University of Cincinnati College of Medicine;
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49
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Payer B, Lee JT. Coupling of X-chromosome reactivation with the pluripotent stem cell state. RNA Biol 2014; 11:798-807. [PMID: 25137047 DOI: 10.4161/rna.29779] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
X-chromosome inactivation (XCI) in female mammals is a dramatic example of epigenetic gene regulation, which entails the silencing of an entire chromosome through a wide range of mechanisms involving noncoding RNAs, chromatin-modifications, and DNA-methylation. While XCI is associated with the differentiated cell state, it is reversed by X-chromosome reactivation (XCR) ex vivo in pluripotent stem cells and in vivo in the early mouse embryo and the germline. Critical in the regulation of XCI vs. XCR is the X-inactivation center, a multigene locus on the X-chromosome harboring several long noncoding RNA genes including, most prominently, Xist and Tsix. These genes, which sit at the top of the XCI hierarchy, are by themselves controlled by pluripotency factors, coupling XCR with the naïve pluripotent stem cell state. In this point-of-view article we review the latest findings regarding this intricate relationship between cell differentiation state and epigenetic control of the X-chromosome. In particular, we discuss the emerging picture of complex multifactorial regulatory mechanisms, ensuring both a fine-tuned and robust X-reactivation process.
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Affiliation(s)
- Bernhard Payer
- Howard Hughes Medical Institute; Department of Molecular Biology; Massachusetts General Hospital; Department of Genetics; Harvard Medical School; Boston, MA USA
| | - Jeannie T Lee
- Howard Hughes Medical Institute; Department of Molecular Biology; Massachusetts General Hospital; Department of Genetics; Harvard Medical School; Boston, MA USA
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50
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Giorgetti L, Galupa R, Nora EP, Piolot T, Lam F, Dekker J, Tiana G, Heard E. Predictive polymer modeling reveals coupled fluctuations in chromosome conformation and transcription. Cell 2014; 157:950-63. [PMID: 24813616 DOI: 10.1016/j.cell.2014.03.025] [Citation(s) in RCA: 327] [Impact Index Per Article: 32.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2013] [Revised: 12/02/2013] [Accepted: 03/06/2014] [Indexed: 11/16/2022]
Abstract
A new level of chromosome organization, topologically associating domains (TADs), was recently uncovered by chromosome conformation capture (3C) techniques. To explore TAD structure and function, we developed a polymer model that can extract the full repertoire of chromatin conformations within TADs from population-based 3C data. This model predicts actual physical distances and to what extent chromosomal contacts vary between cells. It also identifies interactions within single TADs that stabilize boundaries between TADs and allows us to identify and genetically validate key structural elements within TADs. Combining the model's predictions with high-resolution DNA FISH and quantitative RNA FISH for TADs within the X-inactivation center (Xic), we dissect the relationship between transcription and spatial proximity to cis-regulatory elements. We demonstrate that contacts between potential regulatory elements occur in the context of fluctuating structures rather than stable loops and propose that such fluctuations may contribute to asymmetric expression in the Xic during X inactivation.
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Affiliation(s)
- Luca Giorgetti
- Institut Curie, 26 Rue d'Ulm, 75248 Paris Cedex 05, France; CNRS UMR3215, 75248 Paris Cedex 05, France; INSERM U934, 75248 Paris Cedex 05, France
| | - Rafael Galupa
- Institut Curie, 26 Rue d'Ulm, 75248 Paris Cedex 05, France; CNRS UMR3215, 75248 Paris Cedex 05, France; INSERM U934, 75248 Paris Cedex 05, France
| | - Elphège P Nora
- Institut Curie, 26 Rue d'Ulm, 75248 Paris Cedex 05, France
| | - Tristan Piolot
- Institut Curie, 26 Rue d'Ulm, 75248 Paris Cedex 05, France; CNRS UMR3215, 75248 Paris Cedex 05, France; INSERM U934, 75248 Paris Cedex 05, France
| | - France Lam
- Institut Curie, 26 Rue d'Ulm, 75248 Paris Cedex 05, France; CNRS UMR3215, 75248 Paris Cedex 05, France; INSERM U934, 75248 Paris Cedex 05, France
| | - Job Dekker
- Program in Systems Biology, Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, 368 Plantation Street, Worcester, MA 01605-0103, USA
| | - Guido Tiana
- Dipartimento di Fisica, Università degli Studi di Milano and INFN, Via Celoria 16, 20133 Milano, Italy.
| | - Edith Heard
- Institut Curie, 26 Rue d'Ulm, 75248 Paris Cedex 05, France; CNRS UMR3215, 75248 Paris Cedex 05, France; INSERM U934, 75248 Paris Cedex 05, France; Collège de France, 11 place Marcelin-Berthelot, Paris 75005, France.
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