1
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Kanata E, Duffié R, Schulz EG. Establishment and maintenance of random monoallelic expression. Development 2024; 151:dev201741. [PMID: 38813842 PMCID: PMC11166465 DOI: 10.1242/dev.201741] [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: 05/31/2024]
Abstract
This Review elucidates the regulatory principles of random monoallelic expression by focusing on two well-studied examples: the X-chromosome inactivation regulator Xist and the olfactory receptor gene family. Although the choice of a single X chromosome or olfactory receptor occurs in different developmental contexts, common gene regulatory principles guide monoallelic expression in both systems. In both cases, an event breaks the symmetry between genetically and epigenetically identical copies of the gene, leading to the expression of one single random allele, stabilized through negative feedback control. Although many regulatory steps that govern the establishment and maintenance of monoallelic expression have been identified, key pieces of the puzzle are still missing. We provide an overview of the current knowledge and models for the monoallelic expression of Xist and olfactory receptors. We discuss their similarities and differences, and highlight open questions and approaches that could guide the study of other monoallelically expressed genes.
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Affiliation(s)
- Eleni Kanata
- Systems Epigenetics, Otto Warburg Laboratories, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany
| | - Rachel Duffié
- Department of Biochemistry and Molecular Biophysics, Mortimer B. Zuckerman Mind, Brain, and Behavior Institute, Columbia University, New York, NY 10027, USA
| | - Edda G. Schulz
- Systems Epigenetics, Otto Warburg Laboratories, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany
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2
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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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3
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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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4
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Johansson J, Lidéus S, Höijer I, Ameur A, Gudmundsson S, Annerén G, Bondeson ML, Wilbe M. A novel quantitative targeted analysis of X-chromosome inactivation (XCI) using nanopore sequencing. Sci Rep 2023; 13:12856. [PMID: 37553382 PMCID: PMC10409790 DOI: 10.1038/s41598-023-34413-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Accepted: 04/29/2023] [Indexed: 08/10/2023] Open
Abstract
X-chromosome inactivation (XCI) analyses often assist in diagnostics of X-linked traits, however accurate assessment remains challenging with current methods. We developed a novel strategy using amplification-free Cas9 enrichment and Oxford nanopore technologies sequencing called XCI-ONT, to investigate and rigorously quantify XCI in human androgen receptor gene (AR) and human X-linked retinitis pigmentosa 2 gene (RP2). XCI-ONT measures methylation over 116 CpGs in AR and 58 CpGs in RP2, and separate parental X-chromosomes without PCR bias. We show the usefulness of the XCI-ONT strategy over the PCR-based golden standard XCI technique that only investigates one or two CpGs per gene. The results highlight the limitations of using the golden standard technique when the XCI pattern is partially skewed and the advantages of XCI-ONT to rigorously quantify XCI. This study provides a universal XCI-method on DNA, which is highly valuable in clinical and research framework of X-linked traits.
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Affiliation(s)
- Josefin Johansson
- Department of Immunology, Genetics and Pathology, Science for Life Laboratory, Uppsala University, Husargatan 3, Box 815, SE-751 08, Uppsala, Sweden
| | - Sarah Lidéus
- Department of Immunology, Genetics and Pathology, Science for Life Laboratory, Uppsala University, Husargatan 3, Box 815, SE-751 08, Uppsala, Sweden
| | - Ida Höijer
- Department of Immunology, Genetics and Pathology, Science for Life Laboratory, Uppsala University, Husargatan 3, Box 815, SE-751 08, Uppsala, Sweden
| | - Adam Ameur
- Department of Immunology, Genetics and Pathology, Science for Life Laboratory, Uppsala University, Husargatan 3, Box 815, SE-751 08, Uppsala, Sweden
| | - Sanna Gudmundsson
- Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Division of Genetics and Genomics, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA
| | - Göran Annerén
- Department of Immunology, Genetics and Pathology, Science for Life Laboratory, Uppsala University, Husargatan 3, Box 815, SE-751 08, Uppsala, Sweden
| | - Marie-Louise Bondeson
- Department of Immunology, Genetics and Pathology, Science for Life Laboratory, Uppsala University, Husargatan 3, Box 815, SE-751 08, Uppsala, Sweden
| | - Maria Wilbe
- Department of Immunology, Genetics and Pathology, Science for Life Laboratory, Uppsala University, Husargatan 3, Box 815, SE-751 08, Uppsala, Sweden.
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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: 1] [Impact Index Per Article: 1.0] [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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Noviello G, Gjaltema RAF, Schulz EG. CasTuner is a degron and CRISPR/Cas-based toolkit for analog tuning of endogenous gene expression. Nat Commun 2023; 14:3225. [PMID: 37270532 DOI: 10.1038/s41467-023-38909-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Accepted: 05/22/2023] [Indexed: 06/05/2023] Open
Abstract
Certain cellular processes are dose-dependent, requiring specific quantities or stoichiometries of gene products, as exemplified by haploinsufficiency and sex-chromosome dosage compensation. Understanding dosage-sensitive processes requires tools to quantitatively modulate protein abundance. Here we present CasTuner, a CRISPR-based toolkit for analog tuning of endogenous gene expression. The system exploits Cas-derived repressors that are quantitatively tuned by ligand titration through a FKBP12F36V degron domain. CasTuner can be applied at the transcriptional or post-transcriptional level using a histone deacetylase (hHDAC4) fused to dCas9, or the RNA-targeting CasRx, respectively. We demonstrate analog tuning of gene expression homogeneously across cells in mouse and human cells, as opposed to KRAB-dependent CRISPR-interference systems, which exhibit digital repression. Finally, we quantify the system's dynamics and use it to measure dose-response relationships of NANOG and OCT4 with their target genes and with the cellular phenotype. CasTuner thus provides an easy-to-implement tool to study dose-responsive processes in their physiological context.
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Affiliation(s)
- Gemma Noviello
- Systems Epigenetics, Otto Warburg Laboratories, Max Planck Institute for Molecular Genetics, 14195, Berlin, Germany
| | - Rutger A F Gjaltema
- Systems Epigenetics, Otto Warburg Laboratories, Max Planck Institute for Molecular Genetics, 14195, Berlin, Germany
- Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 904, 1098 XH, Amsterdam, The Netherlands
| | - Edda G Schulz
- Systems Epigenetics, Otto Warburg Laboratories, Max Planck Institute for Molecular Genetics, 14195, Berlin, Germany.
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7
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Li J, Ming Z, Yang L, Wang T, Liu G, Ma Q. Long noncoding RNA XIST: Mechanisms for X chromosome inactivation, roles in sex-biased diseases, and therapeutic opportunities. Genes Dis 2022; 9:1478-1492. [PMID: 36157489 PMCID: PMC9485286 DOI: 10.1016/j.gendis.2022.04.007] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Revised: 04/16/2022] [Accepted: 04/18/2022] [Indexed: 11/30/2022] Open
Abstract
Sexual dimorphism has been reported in various human diseases including autoimmune diseases, neurological diseases, pulmonary arterial hypertension, and some types of cancers, although the underlying mechanisms remain poorly understood. The long noncoding RNA (lncRNA) X-inactive specific transcript (XIST) is involved in X chromosome inactivation (XCI) in female placental mammals, a process that ensures the balanced expression dosage of X-linked genes between sexes. XIST is abnormally expressed in many sex-biased diseases. In addition, escape from XIST-mediated XCI and skewed XCI also contribute to sex-biased diseases. Therefore, its expression or modification can be regarded as a biomarker for the diagnosis and prognosis of many sex-biased diseases. Genetic manipulation of XIST expression can inhibit the progression of some of these diseases in animal models, and therefore XIST has been proposed as a potential therapeutic target. In this manuscript, we summarize the current knowledge about the mechanisms for XIST-mediated XCI and the roles of XIST in sex-biased diseases, and discuss potential therapeutic strategies targeting XIST.
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8
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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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9
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Mira-Bontenbal H, Tan B, Gontan C, Goossens S, Boers RG, Boers JB, Dupont C, van Royen ME, IJcken WFJ, French P, Bedalov A, Gribnau J. Genetic and epigenetic determinants of reactivation of Mecp2 and the inactive X chromosome in neural stem cells. Stem Cell Reports 2022; 17:693-706. [PMID: 35148843 PMCID: PMC9039756 DOI: 10.1016/j.stemcr.2022.01.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Revised: 01/10/2022] [Accepted: 01/10/2022] [Indexed: 01/17/2023] Open
Abstract
Rett syndrome may be treated by reactivating the silent copy of Mecp2 from the inactive X chromosome in female cells. Most studies that model Mecp2 reactivation have used mouse fibroblasts rather than neural cells, which would be critical for phenotypic reversal, and rely on fluorescent reporters that lack adequate sensitivity. Here, we present a mouse model based on a dual bioluminescent and fluorescent reporter to assess the level of reactivation of Mecp2 and the inactive X chromosome by treating neural stem cells with 5-azacytidine and Xist knockdown. We show that reactivation of Mecp2 and other X-linked genes correlates with CpG density, with distance from escapees, and, very strongly, with the presence of short interspersed nuclear elements. In addition, X-linked genes reactivated in neural stem cells overlap substantially with early reactivating genes by induced pluripotent stem cell reprogramming of fibroblasts or neuronal progenitors, indicating that X chromosome reactivation follows similar paths regardless of the technique or cell type used.
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Affiliation(s)
- H Mira-Bontenbal
- Oncode Institue, Department of Developmental Biology, Erasmus MC, Rotterdam, the Netherlands.
| | - B Tan
- Oncode Institue, Department of Developmental Biology, Erasmus MC, Rotterdam, the Netherlands
| | - C Gontan
- Oncode Institue, Department of Developmental Biology, Erasmus MC, Rotterdam, the Netherlands
| | - S Goossens
- Oncode Institue, Department of Developmental Biology, Erasmus MC, Rotterdam, the Netherlands
| | - R G Boers
- Oncode Institue, Department of Developmental Biology, Erasmus MC, Rotterdam, the Netherlands
| | - J B Boers
- Oncode Institue, Department of Developmental Biology, Erasmus MC, Rotterdam, the Netherlands
| | - C Dupont
- Oncode Institue, Department of Developmental Biology, Erasmus MC, Rotterdam, the Netherlands
| | - M E van Royen
- Department of Pathology, Erasmus MC, Rotterdam, the Netherlands
| | - W F J IJcken
- Center for Biomics, Department of Cell Biology, Erasmus MC, Rotterdam, the Netherlands
| | - P French
- Department of Neurology, Erasmus MC Cancer Institute, University Medical Center, Rotterdam, the Netherlands
| | - A Bedalov
- Clinical Research Division, Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue N., Seattle, WA 98109, USA
| | - J Gribnau
- Oncode Institue, Department of Developmental Biology, Erasmus MC, Rotterdam, the Netherlands.
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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: 65] [Impact Index Per Article: 32.5] [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: 18] [Impact Index Per Article: 9.0] [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: 15] [Impact Index Per Article: 5.0] [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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Aizawa E, Kaufmann C, Sting S, Boigner S, Freimann R, Di Minin G, Wutz A. Haploid mouse germ cell precursors from embryonic stem cells reveal Xist activation from a single X chromosome. Stem Cell Reports 2021; 17:43-52. [PMID: 34919812 PMCID: PMC8758942 DOI: 10.1016/j.stemcr.2021.11.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Revised: 11/15/2021] [Accepted: 11/15/2021] [Indexed: 12/03/2022] Open
Abstract
Mammalian haploid cells have applications for genetic screening and substituting gametic genomes. Here, we characterize a culture system for obtaining haploid primordial germ cell-like cells (PGCLCs) from haploid mouse embryonic stem cells (ESCs). We find that haploid cells show predisposition for PGCLCs, whereas a large fraction of somatic cells becomes diploid. Characterization of the differentiating haploid ESCs (haESCs) reveals that Xist is activated from and colocalizes with the single X chromosome. This observation suggests that X chromosome inactivation (XCI) is initiated in haploid cells consistent with a model where autosomal blocking factors set a threshold for X-linked activators. We further find that Xist expression is lost at later timepoints in differentiation, which likely reflects the loss of X-linked activators. In vitro differentiation of haploid PGCLCs can be a useful approach for future studies of potential X-linked activators of Xist. A culture system for obtaining haploid PGCLCs Predisposition of haploid cells in the germline over somatic lineages A single X chromosome in haploid cells leads to activation of Xist Mutation of Xist is insufficient to prevent diploidization of haESCs
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Affiliation(s)
- Eishi Aizawa
- Institute of Molecular Health Sciences, Swiss Federal Institute of Technology, ETH Zurich, Zurich, Switzerland
| | - Corinne Kaufmann
- Institute of Molecular Health Sciences, Swiss Federal Institute of Technology, ETH Zurich, Zurich, Switzerland
| | - Sarah Sting
- Institute of Molecular Health Sciences, Swiss Federal Institute of Technology, ETH Zurich, Zurich, Switzerland
| | - Sarah Boigner
- Institute of Molecular Health Sciences, Swiss Federal Institute of Technology, ETH Zurich, Zurich, Switzerland
| | - Remo Freimann
- Institute of Molecular Health Sciences, Swiss Federal Institute of Technology, ETH Zurich, Zurich, Switzerland
| | - Giulio Di Minin
- Institute of Molecular Health Sciences, Swiss Federal Institute of Technology, ETH Zurich, Zurich, Switzerland
| | - Anton Wutz
- Institute of Molecular Health Sciences, Swiss Federal Institute of Technology, ETH Zurich, Zurich, Switzerland.
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14
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Barreto VM, Kubasova N, Alves-Pereira CF, Gendrel AV. X-Chromosome Inactivation and Autosomal Random Monoallelic Expression as "Faux Amis". Front Cell Dev Biol 2021; 9:740937. [PMID: 34631717 PMCID: PMC8495168 DOI: 10.3389/fcell.2021.740937] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Accepted: 08/30/2021] [Indexed: 12/23/2022] Open
Abstract
X-chromosome inactivation (XCI) and random monoallelic expression of autosomal genes (RMAE) are two paradigms of gene expression regulation where, at the single cell level, genes can be expressed from either the maternal or paternal alleles. X-chromosome inactivation takes place in female marsupial and placental mammals, while RMAE has been described in mammals and also other species. Although the outcome of both processes results in random monoallelic expression and mosaicism at the cellular level, there are many important differences. We provide here a brief sketch of the history behind the discovery of XCI and RMAE. Moreover, we review some of the distinctive features of these two phenomena, with respect to when in development they are established, their roles in dosage compensation and cellular phenotypic diversity, and the molecular mechanisms underlying their initiation and stability.
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Affiliation(s)
- Vasco M Barreto
- Chronic Diseases Research Centre, CEDOC, Nova Medical School, Lisbon, Portugal
| | - Nadiya Kubasova
- Chronic Diseases Research Centre, CEDOC, Nova Medical School, Lisbon, Portugal
| | - Clara F Alves-Pereira
- Department of Genetics, Smurfit Institute of Genetics, Trinity College Dublin, University of Dublin, Dublin, Ireland
| | - Anne-Valerie Gendrel
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina da Universidade de Lisboa, Lisbon, Portugal
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15
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Abstract
Nuclei are central hubs for information processing in eukaryotic cells. The need to fit large genomes into small nuclei imposes severe restrictions on genome organization and the mechanisms that drive genome-wide regulatory processes. How a disordered polymer such as chromatin, which has vast heterogeneity in its DNA and histone modification profiles, folds into discernibly consistent patterns is a fundamental question in biology. Outstanding questions include how genomes are spatially and temporally organized to regulate cellular processes with high precision and whether genome organization is causally linked to transcription regulation. The advent of next-generation sequencing, super-resolution imaging, multiplexed fluorescent in situ hybridization, and single-molecule imaging in individual living cells has caused a resurgence in efforts to understand the spatiotemporal organization of the genome. In this review, we discuss structural and mechanistic properties of genome organization at different length scales and examine changes in higher-order chromatin organization during important developmental transitions.
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Affiliation(s)
- Rajarshi P Ghosh
- Department of Molecular and Cell Biology and Howard Hughes Medical Institute, University of California, Berkeley, California 94720, USA; ,
| | - Barbara J Meyer
- Department of Molecular and Cell Biology and Howard Hughes Medical Institute, University of California, Berkeley, California 94720, USA; ,
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16
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Bonora G, Ramani V, Singh R, Fang H, Jackson DL, Srivatsan S, Qiu R, Lee C, Trapnell C, Shendure J, Duan Z, Deng X, Noble WS, Disteche CM. Single-cell landscape of nuclear configuration and gene expression during stem cell differentiation and X inactivation. Genome Biol 2021; 22:279. [PMID: 34579774 PMCID: PMC8474932 DOI: 10.1186/s13059-021-02432-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Accepted: 07/07/2021] [Indexed: 11/25/2022] Open
Abstract
BACKGROUND Mammalian development is associated with extensive changes in gene expression, chromatin accessibility, and nuclear structure. Here, we follow such changes associated with mouse embryonic stem cell differentiation and X inactivation by integrating, for the first time, allele-specific data from these three modalities obtained by high-throughput single-cell RNA-seq, ATAC-seq, and Hi-C. RESULTS Allele-specific contact decay profiles obtained by single-cell Hi-C clearly show that the inactive X chromosome has a unique profile in differentiated cells that have undergone X inactivation. Loss of this inactive X-specific structure at mitosis is followed by its reappearance during the cell cycle, suggesting a "bookmark" mechanism. Differentiation of embryonic stem cells to follow the onset of X inactivation is associated with changes in contact decay profiles that occur in parallel on both the X chromosomes and autosomes. Single-cell RNA-seq and ATAC-seq show evidence of a delay in female versus male cells, due to the presence of two active X chromosomes at early stages of differentiation. The onset of the inactive X-specific structure in single cells occurs later than gene silencing, consistent with the idea that chromatin compaction is a late event of X inactivation. Single-cell Hi-C highlights evidence of discrete changes in nuclear structure characterized by the acquisition of very long-range contacts throughout the nucleus. Novel computational approaches allow for the effective alignment of single-cell gene expression, chromatin accessibility, and 3D chromosome structure. CONCLUSIONS Based on trajectory analyses, three distinct nuclear structure states are detected reflecting discrete and profound simultaneous changes not only to the structure of the X chromosomes, but also to that of autosomes during differentiation. Our study reveals that long-range structural changes to chromosomes appear as discrete events, unlike progressive changes in gene expression and chromatin accessibility.
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Affiliation(s)
- Giancarlo Bonora
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
| | - Vijay Ramani
- Department of Biochemistry & Biophysics, University of California San Francisco, San Francisco, CA, USA
| | - Ritambhara Singh
- Department of Computer Science, Brown University, Providence, RI, USA
- Center for Computational Molecular Biology, Brown University, Providence, RI, USA
| | - He Fang
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA, USA
| | - Dana L Jackson
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
| | - Sanjay Srivatsan
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
| | - Ruolan Qiu
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
| | - Choli Lee
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
| | - Cole Trapnell
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
- Brotman Baty Institute for Precision Medicine, Seattle, WA, USA
- Allen Discovery Center for Cell Lineage Tracing, Seattle, WA, USA
| | - Jay Shendure
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
- Brotman Baty Institute for Precision Medicine, Seattle, WA, USA
- Allen Discovery Center for Cell Lineage Tracing, Seattle, WA, USA
- Howard Hughes Medical Institute, Seattle, WA, USA
| | - Zhijun Duan
- Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, USA
- Division of Hematology, Department of Medicine, University of Washington, Seattle, USA
| | - Xinxian Deng
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA, USA.
| | - William S Noble
- Department of Genome Sciences, University of Washington, Seattle, WA, USA.
- Paul G. Allen School of Computer Science and Engineering, University of Washington, Seattle, WA, USA.
| | - Christine M Disteche
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA, USA.
- Brotman Baty Institute for Precision Medicine, Seattle, WA, USA.
- Department of Medicine, University of Washington, Seattle, WA, USA.
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17
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Pereira G, Dória S. X-chromosome inactivation: implications in human disease. J Genet 2021. [DOI: 10.1007/s12041-021-01314-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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18
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Pacini G, Dunkel I, Mages N, Mutzel V, Timmermann B, Marsico A, Schulz EG. Integrated analysis of Xist upregulation and X-chromosome inactivation with single-cell and single-allele resolution. Nat Commun 2021; 12:3638. [PMID: 34131144 PMCID: PMC8206119 DOI: 10.1038/s41467-021-23643-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Accepted: 05/11/2021] [Indexed: 12/20/2022] Open
Abstract
To ensure dosage compensation between the sexes, one randomly chosen X chromosome is silenced in each female cell in the process of X-chromosome inactivation (XCI). XCI is initiated during early development through upregulation of the long non-coding RNA Xist, which mediates chromosome-wide gene silencing. Cell differentiation, Xist upregulation and gene silencing are thought to be coupled at multiple levels to ensure inactivation of exactly one out of two X chromosomes. Here we perform an integrated analysis of all three processes through allele-specific single-cell RNA-sequencing. Specifically, we assess the onset of random XCI in differentiating mouse embryonic stem cells, and develop dedicated analysis approaches. By exploiting the inter-cellular heterogeneity of XCI onset, we identify putative Xist regulators. Moreover, we show that transient Xist upregulation from both X chromosomes results in biallelic gene silencing right before transitioning to the monoallelic state, confirming a prediction of the stochastic model of XCI. Finally, we show that genetic variation modulates the XCI process at multiple levels, providing a potential explanation for the long-known X-controlling element (Xce) effect, which leads to preferential inactivation of a specific X chromosome in inter-strain crosses. We thus draw a detailed picture of the different levels of regulation that govern the initiation of XCI. The experimental and computational strategies we have developed here will allow us to profile random XCI in more physiological contexts, including primary human cells in vivo.
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Affiliation(s)
- Guido Pacini
- Otto Warburg Laboratories, Max Planck Institute for Molecular Genetics, Berlin, Germany
| | - Ilona Dunkel
- Otto Warburg Laboratories, Max Planck Institute for Molecular Genetics, Berlin, Germany
| | - Norbert Mages
- Sequencing core facility, Max Planck Institute for Molecular Genetics, Berlin, Germany
| | - Verena Mutzel
- Otto Warburg Laboratories, Max Planck Institute for Molecular Genetics, Berlin, Germany
| | - Bernd Timmermann
- Sequencing core facility, Max Planck Institute for Molecular Genetics, Berlin, Germany
| | - Annalisa Marsico
- Institute for Computational Biology, Helmholtz Center, München, Germany.
| | - Edda G Schulz
- Otto Warburg Laboratories, Max Planck Institute for Molecular Genetics, Berlin, Germany.
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19
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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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20
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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: 16] [Impact Index Per Article: 5.3] [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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21
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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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22
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Aeby E, Lee HG, Lee YW, Kriz A, del Rosario BC, Oh HJ, Boukhali M, Haas W, Lee JT. Decapping enzyme 1A breaks X-chromosome symmetry by controlling Tsix elongation and RNA turnover. Nat Cell Biol 2020; 22:1116-1129. [PMID: 32807903 DOI: 10.1038/s41556-020-0558-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Accepted: 07/09/2020] [Indexed: 12/27/2022]
Abstract
How allelic asymmetry is generated remains a major unsolved problem in epigenetics. Here we model the problem using X-chromosome inactivation by developing "BioRBP", an enzymatic RNA-proteomic method that enables probing of low-abundance interactions and an allelic RNA-depletion and -tagging system. We identify messenger RNA-decapping enzyme 1A (DCP1A) as a key regulator of Tsix, a noncoding RNA implicated in allelic choice through X-chromosome pairing. DCP1A controls Tsix half-life and transcription elongation. Depleting DCP1A causes accumulation of X-X pairs and perturbs the transition to monoallelic Tsix expression required for Xist upregulation. While ablating DCP1A causes hyperpairing, forcing Tsix degradation resolves pairing and enables Xist upregulation. We link pairing to allelic partitioning of CCCTC-binding factor (CTCF) and show that tethering DCP1A to one Tsix allele is sufficient to drive monoallelic Xist expression. Thus, DCP1A flips a bistable switch for the mutually exclusive determination of active and inactive Xs.
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23
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Markodimitraki CM, Rang FJ, Rooijers K, de Vries SS, Chialastri A, de Luca KL, Lochs SJA, Mooijman D, Dey SS, Kind J. Simultaneous quantification of protein-DNA interactions and transcriptomes in single cells with scDam&T-seq. Nat Protoc 2020; 15:1922-1953. [PMID: 32350457 PMCID: PMC7779467 DOI: 10.1038/s41596-020-0314-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Accepted: 02/17/2020] [Indexed: 12/31/2022]
Abstract
Protein-DNA interactions are essential for establishing cell type-specific chromatin architecture and gene expression. We recently developed scDam&T-seq, a multi-omics method that can simultaneously quantify protein-DNA interactions and the transcriptome in single cells. The method effectively combines two existing methods: DNA adenine methyltransferase identification (DamID) and CEL-Seq2. DamID works through the tethering of a protein of interest (POI) to the Escherichia coli DNA adenine methyltransferase (Dam). Upon expression of this fusion protein, DNA in proximity to the POI is methylated by Dam and can be selectively digested and amplified. CEL-Seq2, in contrast, makes use of poly-dT primers to reverse transcribe mRNA, followed by linear amplification through in vitro transcription. scDam&T-seq is the first technique capable of providing a combined readout of protein-DNA contact and transcription from single-cell samples. Once suitable cell lines have been established, the protocol can be completed in 5 d, with a throughput of hundreds to thousands of cells. The processing of raw sequencing data takes an additional 1-2 d. Our method can be used to understand the transcriptional changes a cell undergoes upon the DNA binding of a POI. It can be performed in any laboratory with access to FACS, robotic and high-throughput-sequencing facilities.
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Affiliation(s)
- Corina M Markodimitraki
- Oncode Institute, Hubrecht Institute-KNAW and University Medical Center Utrecht, Utrecht, the Netherlands
| | - Franka J Rang
- Oncode Institute, Hubrecht Institute-KNAW and University Medical Center Utrecht, Utrecht, the Netherlands
| | - Koos Rooijers
- Oncode Institute, Hubrecht Institute-KNAW and University Medical Center Utrecht, Utrecht, the Netherlands
| | - Sandra S de Vries
- Oncode Institute, Hubrecht Institute-KNAW and University Medical Center Utrecht, Utrecht, the Netherlands
| | - Alex Chialastri
- Department of Chemical Engineering, University of California Santa Barbara, Santa Barbara, CA, USA
- Center for Bioengineering, University of California Santa Barbara, Santa Barbara, CA, USA
| | - Kim L de Luca
- Oncode Institute, Hubrecht Institute-KNAW and University Medical Center Utrecht, Utrecht, the Netherlands
| | - Silke J A Lochs
- Oncode Institute, Hubrecht Institute-KNAW and University Medical Center Utrecht, Utrecht, the Netherlands
| | - Dylan Mooijman
- Oncode Institute, Hubrecht Institute-KNAW and University Medical Center Utrecht, Utrecht, the Netherlands
- Genome Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Siddharth S Dey
- Department of Chemical Engineering, University of California Santa Barbara, Santa Barbara, CA, USA.
- Center for Bioengineering, University of California Santa Barbara, Santa Barbara, CA, USA.
| | - Jop Kind
- Oncode Institute, Hubrecht Institute-KNAW and University Medical Center Utrecht, Utrecht, the Netherlands.
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24
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Distinct features of nucleolus-associated domains in mouse embryonic stem cells. Chromosoma 2020; 129:121-139. [PMID: 32219510 DOI: 10.1007/s00412-020-00734-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Revised: 03/09/2020] [Accepted: 03/12/2020] [Indexed: 10/24/2022]
Abstract
Heterochromatin in eukaryotic interphase cells frequently localizes to the nucleolar periphery (nucleolus-associated domains (NADs)) and the nuclear lamina (lamina-associated domains (LADs)). Gene expression in somatic cell NADs is generally low, but NADs have not been characterized in mammalian stem cells. Here, we generated the first genome-wide map of NADs in mouse embryonic stem cells (mESCs) via deep sequencing of chromatin associated with biochemically purified nucleoli. As we had observed in mouse embryonic fibroblasts (MEFs), the large type I subset of NADs overlaps with constitutive LADs and is enriched for features of constitutive heterochromatin, including late replication timing and low gene density and expression levels. Conversely, the type II NAD subset overlaps with loci that are not lamina-associated, but in mESCs, type II NADs are much less abundant than in MEFs. mESC NADs are also much less enriched in H3K27me3 modified regions than are NADs in MEFs. Additionally, comparision of MEF and mESC NADs revealed enrichment of developmentally regulated genes in cell-type-specific NADs. Together, these data indicate that NADs are a developmentally dynamic component of heterochromatin. These studies implicate association with the nucleolar periphery as a mechanism for developmentally regulated gene expression and will facilitate future studies of NADs during mESC differentiation.
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25
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Wang F, Bach I. Rlim/Rnf12, Rex1, and X Chromosome Inactivation. Front Cell Dev Biol 2019; 7:258. [PMID: 31737626 PMCID: PMC6834644 DOI: 10.3389/fcell.2019.00258] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Accepted: 10/16/2019] [Indexed: 12/28/2022] Open
Abstract
RLIM/Rnf12 is an E3 ubiquitin ligase that has originally been identified as a transcriptional cofactor associated with LIM domain transcription factors. Indeed, this protein modulates transcriptional activities and multiprotein complexes recruited by several classes of transcription factors thereby enhancing or repressing transcription. Around 10 years ago, RLIM/Rnf12 has been identified as a major regulator for the process of X chromosome inactivation (XCI), the transcriptional silencing of one of the two X chromosomes in female mice and ESCs. However, the precise roles of RLIM during XCI have been controversial. Here, we discuss the cellular and developmental functions of RLIM as an E3 ubiquitin ligase and its roles during XCI in conjunction with its target protein Rex1.
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Affiliation(s)
- Feng Wang
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Medical School, Worcester, MA, United States
| | - Ingolf Bach
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Medical School, Worcester, MA, United States
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26
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Stork C, Li Z, Lin L, Zheng S. Developmental Xist induction is mediated by enhanced splicing. Nucleic Acids Res 2019; 47:1532-1543. [PMID: 30496473 PMCID: PMC6379716 DOI: 10.1093/nar/gky1198] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Revised: 11/12/2018] [Accepted: 11/15/2018] [Indexed: 11/12/2022] Open
Abstract
X-inactive-specific transcript (Xist) is a long noncoding RNA (lncRNA) essential for inactivating one of the two X chromosomes in mammalian females. Random X chromosome inactivation is mediated by Xist RNA expressed from the inactive X chromosome. We found that Xist RNA is unspliced in naïve embryonic stem (ES) cells. Upon differentiation, Xist splicing becomes efficient across all exons independent of transcription, suggesting interdependent or coordinated removal of Xist introns. In female cells with mutated polypyrimidine tract binding protein 1 (Ptbp1), differentiation fails to substantially upregulate mature Xist RNA because of a defect in Xist splicing. We further found both Xist129 and XistCAS RNA are unspliced in Mus musculus 129SvJ/Mus castaneous (CAS) hybrid female ES cells. Upon differentiation, Xist129 exhibits a higher splicing efficiency than XistCAS, likely contributing to preferential inhibition of the X129 chromosome. Single cell analysis shows that the allelic choice of Xist splicing is linked to the inactive X chromosome. We conclude post-transcriptional control of Xist RNA splicing is an essential regulatory step of Xist induction. Our studies shed light on the developmental roles of splicing for nuclear-retained Xist lncRNA and suggest inefficient Xist splicing is an additional fail-safe mechanism to prevent Xist activity in ES cells.
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Affiliation(s)
- Cheryl Stork
- Graduate Program in Cell, Molecular and Developmental Biology, University of California, Riverside, Riverside, CA 92521, USA
| | - Zhelin Li
- Graduate Program in Genetics, Genomics and Bioinformatics, University of California, Riverside, Riverside, CA 92521, USA
| | - Lin Lin
- Division of Biomedical Sciences, University of California, Riverside, Riverside, CA 92521, USA
| | - Sika Zheng
- Graduate Program in Cell, Molecular and Developmental Biology, University of California, Riverside, Riverside, CA 92521, USA.,Graduate Program in Genetics, Genomics and Bioinformatics, University of California, Riverside, Riverside, CA 92521, USA.,Division of Biomedical Sciences, University of California, Riverside, Riverside, CA 92521, USA
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27
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Simultaneous quantification of protein-DNA contacts and transcriptomes in single cells. Nat Biotechnol 2019; 37:766-772. [PMID: 31209373 PMCID: PMC6609448 DOI: 10.1038/s41587-019-0150-y] [Citation(s) in RCA: 61] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Revised: 04/26/2019] [Accepted: 05/09/2019] [Indexed: 01/08/2023]
Abstract
Protein-DNA interactions are critical to the regulation of gene expression, but it remains challenging to define how cell-to-cell heterogeneity in protein-DNA binding influences gene expression variability. Here we report a method for the simultaneous quantification of protein-DNA contacts by combining single-cell DNA adenine methyltransferase identification (DamID) with messenger RNA sequencing of the same cell (scDam&T-seq). We apply scDam&T-seq to reveal how genome-lamina contacts or chromatin accessibility correlate with gene expression in individual cells. Furthermore, we provide single-cell genome-wide interaction data on a polycomb-group protein, RING1B, and the associated transcriptome. Our results show that scDam&T-seq is sensitive enough to distinguish mouse embryonic stem cells cultured under different conditions and their different chromatin landscapes. Our method will enable the analysis of protein-mediated mechanisms that regulate cell-type-specific transcriptional programs in heterogeneous tissues.
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28
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Laskowski AI, Neems DS, Laster K, Strojny-Okyere C, Rice EL, Konieczna IM, Voss JH, Mathew JM, Leventhal JR, Ramsey-Goldman R, Smith ED, Kosak ST. Varying levels of X chromosome coalescence in female somatic cells alters the balance of X-linked dosage compensation and is implicated in female-dominant systemic lupus erythematosus. Sci Rep 2019; 9:8011. [PMID: 31142749 PMCID: PMC6541617 DOI: 10.1038/s41598-019-44229-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Accepted: 05/08/2019] [Indexed: 11/25/2022] Open
Abstract
The three-dimensional organization of the genome in mammalian interphase nuclei is intrinsically linked to the regulation of gene expression. Whole chromosome territories and their encoded gene loci occupy preferential positions within the nucleus that changes according to the expression profile of a given cell lineage or stage. To further illuminate the relationship between chromosome organization, epigenetic environment, and gene expression, here we examine the functional organization of chromosome X and corresponding X-linked genes in a variety of healthy human and disease state X diploid (XX) cells. We observe high frequencies of homologous chromosome X colocalization (or coalescence), typically associated with initiation of X-chromosome inactivation, occurring in XX cells outside of early embryogenesis. Moreover, during chromosome X coalescence significant changes in Xist, H3K27me3, and X-linked gene expression occur, suggesting the potential exchange of gene regulatory information between the active and inactive X chromosomes. We also observe significant differences in chromosome X coalescence in disease-implicated lymphocytes isolated from systemic lupus erythematosus (SLE) patients compared to healthy controls. These results demonstrate that X chromosomes can functionally interact outside of embryogenesis when X inactivation is initiated and suggest a potential gene regulatory mechanism aberration underlying the increased frequency of autoimmunity in XX individuals.
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Affiliation(s)
- Agnieszka I Laskowski
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA
| | - Daniel S Neems
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA
| | - Kyle Laster
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA
| | - Chelsee Strojny-Okyere
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA
| | - Ellen L Rice
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA
| | - Iwona M Konieczna
- Comprehensive Transplant Center, Department of Medicine, Surgery Division, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA
| | - Jessica H Voss
- Comprehensive Transplant Center, Department of Medicine, Surgery Division, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA
| | - James M Mathew
- Comprehensive Transplant Center, Department of Medicine, Surgery Division, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA
| | - Joseph R Leventhal
- Comprehensive Transplant Center, Department of Medicine, Surgery Division, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA
| | - Rosalind Ramsey-Goldman
- Deparment of Medicine, Rheumatology Division, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA
| | - Erica D Smith
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA
| | - Steven T Kosak
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, Chicago, IL, 60611, USA.
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29
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Genome-lamina interactions are established de novo in the early mouse embryo. Nature 2019; 569:729-733. [PMID: 31118510 PMCID: PMC6546605 DOI: 10.1038/s41586-019-1233-0] [Citation(s) in RCA: 75] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Accepted: 04/12/2019] [Indexed: 01/08/2023]
Abstract
In mammals, the emergence of totipotency after fertilization involves extensive rearrangements of the spatial positioning of the genome1,2. However, the contribution of spatial genome organization to the regulation of developmental programs is unclear3. Here we generate high-resolution maps of genomic interactions with the nuclear lamina (a filamentous meshwork that lines the inner nuclear membrane) in mouse pre-implantation embryos. We reveal that nuclear organization is not inherited from the maternal germline but is instead established de novo shortly after fertilization. The two parental genomes establish lamina-associated domains (LADs)4 with different features that converge after the 8-cell stage. We find that the mechanism of LAD establishment is unrelated to DNA replication. Instead, we show that paternal LAD formation in zygotes is prevented by ectopic expression of Kdm5b, which suggests that LAD establishment may be dependent on remodelling of H3K4 methylation. Our data suggest a step-wise assembly model whereby early LAD formation precedes consolidation of topologically associating domains.
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30
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Mutzel V, Okamoto I, Dunkel I, Saitou M, Giorgetti L, Heard E, Schulz EG. A symmetric toggle switch explains the onset of random X inactivation in different mammals. Nat Struct Mol Biol 2019; 26:350-360. [PMID: 30962582 PMCID: PMC6558282 DOI: 10.1038/s41594-019-0214-1] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2018] [Accepted: 03/07/2019] [Indexed: 12/31/2022]
Abstract
Gene-regulatory networks control establishment and maintenance of alternative gene expression states during development. A particular challenge is the acquisition of opposing states by two copies of the same gene, as it is the case in mammals for Xist at the onset of random X-chromosome inactivation (XCI). The regulatory principles that lead to stable mono-allelic expression of Xist remain unknown. Here, we uncovered the minimal Xist regulatory network, by combining mathematical modeling and experimental validation of central model predictions. We identified a symmetric toggle switch as the basis for random mono-allelic Xist up-regulation, which reproduces data from several mutant, aneuploid and polyploid murine cell lines with various Xist expression patterns. Moreover, this toggle switch explains the diversity of strategies employed by different species at the onset of XCI. In addition to providing a unifying conceptual framework to explore X-chromosome inactivation across mammals, our study sets the stage for identifying the molecular mechanisms required to initiate random XCI.
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Affiliation(s)
- Verena Mutzel
- Otto Warburg Laboratories, Max Planck Institute for Molecular Genetics, Berlin, Germany
| | - Ikuhiro Okamoto
- Department of Anatomy and Cell Biology, Graduate School of Medicine, Kyoto University, Kyoto, Japan.,Japan Science and Technology (JST), Exploratory Research for Advanced Technology (ERATO), Kyoto, Japan
| | - Ilona Dunkel
- Otto Warburg Laboratories, Max Planck Institute for Molecular Genetics, Berlin, Germany
| | - Mitinori Saitou
- Institute for the Advanced Study of Human Biology (ASHBi), Kyoto University, Kyoto, Japan.,Department of Anatomy and Cell Biology, Graduate School of Medicine, Kyoto University, Kyoto, Japan.,Center for iPS Cell Research and Application (CiRA), Kyoto University, Kyoto, Japan
| | - Luca Giorgetti
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
| | - Edith Heard
- Institut Curie, PSL Research University, CNRS UMR3215, INSERM U934, Paris, France.,European Molecular Biology Laboratory (EMBL), Directors' research unit, Heidelberg, Germany
| | - Edda G Schulz
- Otto Warburg Laboratories, Max Planck Institute for Molecular Genetics, Berlin, Germany.
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31
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Loss of p53 Causes Stochastic Aberrant X-Chromosome Inactivation and Female-Specific Neural Tube Defects. Cell Rep 2019; 27:442-454.e5. [DOI: 10.1016/j.celrep.2019.03.048] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Revised: 02/11/2019] [Accepted: 03/13/2019] [Indexed: 12/13/2022] Open
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32
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Xist/Tsix expression dynamics during mouse peri-implantation development revealed by whole-mount 3D RNA-FISH. Sci Rep 2019; 9:3637. [PMID: 30842444 PMCID: PMC6403393 DOI: 10.1038/s41598-019-38807-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Accepted: 12/11/2018] [Indexed: 12/31/2022] Open
Abstract
During peri-implantation development in mice, X chromosome inactivation (XCI) status changes dynamically. Here, we examined the expression of Xist and its antisense partner, Tsix, via whole-mount 3D RNA-FISH using strand-specific probes and evaluated XCI status. The results indicate that Xist expression disappears completely by embryonic day (E) 4.5 without Tsix activation in the ICM and that Xist re-expression occurs at E4.75 in some cells, suggesting that random XCI is already initiated in these cells. Intriguingly, epiblast cells exhibiting biallelic Xist expression were observed frequently (~15%) at E5.25 and E5.5. Immunostaining analysis of epigenetic modifications suggests that global change in epigenomic status occurs concomitantly with the transition from imprinted to random XCI. However, global upregulation of H3K27me3 modifications initiated earlier than other modifications, occurring specifically in ICM during progression of Xist erasure. Although both Xist expression and imprinted XCI are thought to be stable in the primitive endoderm/visceral endoderm and trophectoderm/extraembryonic ectoderm lineages, transient loss of Xist clouds was noted only in a subset of extraembryonic ectodermal cells, suggesting distinct features of Xist regulation among the three different embryonic tissue layers. These results will serve as a basis for future functional studies of XCI regulation in vivo.
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33
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Sima J, Chakraborty A, Dileep V, Michalski M, Klein KN, Holcomb NP, Turner JL, Paulsen MT, Rivera-Mulia JC, Trevilla-Garcia C, Bartlett DA, Zhao PA, Washburn BK, Nora EP, Kraft K, Mundlos S, Bruneau BG, Ljungman M, Fraser P, Ay F, Gilbert DM. Identifying cis Elements for Spatiotemporal Control of Mammalian DNA Replication. Cell 2019; 176:816-830.e18. [PMID: 30595451 PMCID: PMC6546437 DOI: 10.1016/j.cell.2018.11.036] [Citation(s) in RCA: 106] [Impact Index Per Article: 21.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Revised: 10/01/2018] [Accepted: 11/21/2018] [Indexed: 01/09/2023]
Abstract
The temporal order of DNA replication (replication timing [RT]) is highly coupled with genome architecture, but cis-elements regulating either remain elusive. We created a series of CRISPR-mediated deletions and inversions of a pluripotency-associated topologically associating domain (TAD) in mouse ESCs. CTCF-associated domain boundaries were dispensable for RT. CTCF protein depletion weakened most TAD boundaries but had no effect on RT or A/B compartmentalization genome-wide. By contrast, deletion of three intra-TAD CTCF-independent 3D contact sites caused a domain-wide early-to-late RT shift, an A-to-B compartment switch, weakening of TAD architecture, and loss of transcription. The dispensability of TAD boundaries and the necessity of these "early replication control elements" (ERCEs) was validated by deletions and inversions at additional domains. Our results demonstrate that discrete cis-regulatory elements orchestrate domain-wide RT, A/B compartmentalization, TAD architecture, and transcription, revealing fundamental principles linking genome structure and function.
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Affiliation(s)
- Jiao Sima
- Department of Biological Science, Florida State University, Tallahassee, FL 32306, USA
| | | | - Vishnu Dileep
- Department of Biological Science, Florida State University, Tallahassee, FL 32306, USA
| | - Marco Michalski
- Nuclear Dynamics Program, The Babraham Institute, Cambridge CB22 3AT, UK
| | - Kyle N Klein
- Department of Biological Science, Florida State University, Tallahassee, FL 32306, USA
| | - Nicolas P Holcomb
- Department of Biological Science, Florida State University, Tallahassee, FL 32306, USA
| | - Jesse L Turner
- Department of Biological Science, Florida State University, Tallahassee, FL 32306, USA
| | - Michelle T Paulsen
- Departments of Radiation Oncology and Environmental Health Sciences, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | | | | | - Daniel A Bartlett
- Department of Biological Science, Florida State University, Tallahassee, FL 32306, USA
| | - Peiyao A Zhao
- Department of Biological Science, Florida State University, Tallahassee, FL 32306, USA
| | - Brian K Washburn
- Department of Biological Science, Florida State University, Tallahassee, FL 32306, USA
| | - Elphège P Nora
- Gladstone Institute of Cardiovascular Disease and Roddenberry Center for Stem Cell Biology and Medicine, San Francisco, CA 94158, USA
| | - Katerina Kraft
- Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany; Institute for Medical and Human Genetics, Charité Universitäts Medizin Berlin, 13353 Berlin, Germany
| | - Stefan Mundlos
- Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany; Institute for Medical and Human Genetics, Charité Universitäts Medizin Berlin, 13353 Berlin, Germany
| | - Benoit G Bruneau
- Gladstone Institute of Cardiovascular Disease and Roddenberry Center for Stem Cell Biology and Medicine, San Francisco, CA 94158, USA; Department of Pediatrics, Cardiovascular Research Institute, University of California at San Francisco, San Francisco, CA 94158, USA; Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Mats Ljungman
- Departments of Radiation Oncology and Environmental Health Sciences, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Peter Fraser
- Department of Biological Science, Florida State University, Tallahassee, FL 32306, USA; Nuclear Dynamics Program, The Babraham Institute, Cambridge CB22 3AT, UK
| | - Ferhat Ay
- La Jolla Institute for Allergy and Immunology, La Jolla, CA 92037, USA; UC San Diego, School of Medicine, La Jolla, CA 92037, USA
| | - David M Gilbert
- Department of Biological Science, Florida State University, Tallahassee, FL 32306, USA.
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34
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REX1 is the critical target of RNF12 in imprinted X chromosome inactivation in mice. Nat Commun 2018; 9:4752. [PMID: 30420655 PMCID: PMC6232137 DOI: 10.1038/s41467-018-07060-w] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Accepted: 10/05/2018] [Indexed: 01/15/2023] Open
Abstract
In mice, imprinted X chromosome inactivation (iXCI) of the paternal X in the pre-implantation embryo and extraembryonic tissues is followed by X reactivation in the inner cell mass (ICM) of the blastocyst to facilitate initiation of random XCI (rXCI) in all embryonic tissues. RNF12 is an E3 ubiquitin ligase that plays a key role in XCI. RNF12 targets pluripotency protein REX1 for degradation to initiate rXCI in embryonic stem cells (ESCs) and loss of the maternal copy of Rnf12 leads to embryonic lethality due to iXCI failure. Here, we show that loss of Rex1 rescues the rXCI phenotype observed in Rnf12−/− ESCs, and that REX1 is the prime target of RNF12 in ESCs. Genetic ablation of Rex1 in Rnf12−/− mice rescues the Rnf12−/− iXCI phenotype, and results in viable and fertile Rnf12−/−:Rex1−/− female mice displaying normal iXCI and rXCI. Our results show that REX1 is the critical target of RNF12 in XCI. REX1 has been shown to regulate pluripotency of ESCs, genomic imprinting and preimplantation development in mice. Here the authors provide evidence that REX1 is the prime target of RNF12 E3 ubiquitin ligase and that Rex1 removal rescues the Rnf12 knockout phenotype in imprinted X chromosome inactivation in mice.
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35
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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: 142] [Impact Index Per Article: 23.7] [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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36
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Sousa EJ, Stuart HT, Bates LE, Ghorbani M, Nichols J, Dietmann S, Silva JCR. Exit from Naive Pluripotency Induces a Transient X Chromosome Inactivation-like State in Males. Cell Stem Cell 2018; 22:919-928.e6. [PMID: 29804891 PMCID: PMC5989057 DOI: 10.1016/j.stem.2018.05.001] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Revised: 12/21/2017] [Accepted: 05/01/2018] [Indexed: 02/06/2023]
Abstract
A hallmark of naive pluripotency is the presence of two active X chromosomes in females. It is not clear whether prevention of X chromosome inactivation (XCI) is mediated by gene networks that preserve the naive state. Here, we show that robust naive pluripotent stem cell (nPSC) self-renewal represses expression of Xist, the master regulator of XCI. We found that nPSCs accumulate Xist on the male X chromosome and on both female X chromosomes as they become NANOG negative at the onset of differentiation. This is accompanied by the appearance of a repressive chromatin signature and partial X-linked gene silencing, suggesting a transient and rapid XCI-like state in male nPSCs. In the embryo, Xist is transiently expressed in males and in females from both X chromosomes at the onset of naive epiblast differentiation. In conclusion, we propose that XCI initiation is gender independent and triggered by destabilization of naive identity, suggesting that gender-specific mechanisms follow, rather than precede, XCI initiation.
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Affiliation(s)
- Elsa J Sousa
- Wellcome-MRC Cambridge Stem Cell Institute, University of Cambridge, Cambridge CB2 1QR, UK; Graduate Program in Areas of Basic and Applied Biology, Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, 4050-313 Porto, Portugal
| | - Hannah T Stuart
- Wellcome-MRC Cambridge Stem Cell Institute, University of Cambridge, Cambridge CB2 1QR, UK; Department of Biochemistry, University of Cambridge, Cambridge CB2 1GA, UK
| | - Lawrence E Bates
- Wellcome-MRC Cambridge Stem Cell Institute, University of Cambridge, Cambridge CB2 1QR, UK; Department of Biochemistry, University of Cambridge, Cambridge CB2 1GA, UK
| | | | - Jennifer Nichols
- Wellcome-MRC Cambridge Stem Cell Institute, University of Cambridge, Cambridge CB2 1QR, UK; Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3EG, UK
| | - Sabine Dietmann
- Wellcome-MRC Cambridge Stem Cell Institute, University of Cambridge, Cambridge CB2 1QR, UK
| | - José C R Silva
- Wellcome-MRC Cambridge Stem Cell Institute, University of Cambridge, Cambridge CB2 1QR, UK; Department of Biochemistry, University of Cambridge, Cambridge CB2 1GA, UK.
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37
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Rivera-Mulia JC, Dimond A, Vera D, Trevilla-Garcia C, Sasaki T, Zimmerman J, Dupont C, Gribnau J, Fraser P, Gilbert DM. Allele-specific control of replication timing and genome organization during development. Genome Res 2018; 28:800-811. [PMID: 29735606 PMCID: PMC5991511 DOI: 10.1101/gr.232561.117] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Accepted: 04/26/2018] [Indexed: 12/14/2022]
Abstract
DNA replication occurs in a defined temporal order known as the replication-timing (RT) program. RT is regulated during development in discrete chromosomal units, coordinated with transcriptional activity and 3D genome organization. Here, we derived distinct cell types from F1 hybrid musculus × castaneus mouse crosses and exploited the high single-nucleotide polymorphism (SNP) density to characterize allelic differences in RT (Repli-seq), genome organization (Hi-C and promoter-capture Hi-C), gene expression (total nuclear RNA-seq), and chromatin accessibility (ATAC-seq). We also present HARP, a new computational tool for sorting SNPs in phased genomes to efficiently measure allele-specific genome-wide data. Analysis of six different hybrid mESC clones with different genomes (C57BL/6, 129/sv, and CAST/Ei), parental configurations, and gender revealed significant RT asynchrony between alleles across ∼12% of the autosomal genome linked to subspecies genomes but not to parental origin, growth conditions, or gender. RT asynchrony in mESCs strongly correlated with changes in Hi-C compartments between alleles but not as strongly with SNP density, gene expression, imprinting, or chromatin accessibility. We then tracked mESC RT asynchronous regions during development by analyzing differentiated cell types, including extraembryonic endoderm stem (XEN) cells, four male and female primary mouse embryonic fibroblasts (MEFs), and neural precursor cells (NPCs) differentiated in vitro from mESCs with opposite parental configurations. We found that RT asynchrony and allelic discordance in Hi-C compartments seen in mESCs were largely lost in all differentiated cell types, accompanied by novel sites of allelic asynchrony at a considerably smaller proportion of the genome, suggesting that genome organization of homologs converges to similar folding patterns during cell fate commitment.
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Affiliation(s)
- Juan Carlos Rivera-Mulia
- Department of Biological Science, Florida State University, Tallahassee, Florida 32306-4295, USA
| | - Andrew Dimond
- The Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, United Kingdom
| | - Daniel Vera
- Center for Genomics and Personalized Medicine, Florida State University, Tallahassee, Florida 32306, USA
| | - Claudia Trevilla-Garcia
- Department of Biological Science, Florida State University, Tallahassee, Florida 32306-4295, USA
| | - Takayo Sasaki
- Department of Biological Science, Florida State University, Tallahassee, Florida 32306-4295, USA
| | - Jared Zimmerman
- Department of Biological Science, Florida State University, Tallahassee, Florida 32306-4295, USA
| | - Catherine Dupont
- Department of Reproduction and Development, Erasmus MC, University Medical Center, 3015GE Rotterdam, The Netherlands
| | - Joost Gribnau
- Department of Reproduction and Development, Erasmus MC, University Medical Center, 3015GE Rotterdam, The Netherlands
| | - Peter Fraser
- Department of Biological Science, Florida State University, Tallahassee, Florida 32306-4295, USA
- The Babraham Institute, Babraham Research Campus, Cambridge CB22 3AT, United Kingdom
- Center for Genomics and Personalized Medicine, Florida State University, Tallahassee, Florida 32306, USA
| | - David M Gilbert
- Department of Biological Science, Florida State University, Tallahassee, Florida 32306-4295, USA
- Center for Genomics and Personalized Medicine, Florida State University, Tallahassee, Florida 32306, USA
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38
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de Hoon B, Splinter E, Eussen B, Douben JCW, Rentmeester E, van de Heijning M, Laven JSE, de Klein JEMM, Liebelt J, Gribnau J. X chromosome inactivation in a female carrier of a 1.28 Mb deletion encompassing the human X inactivation centre. Philos Trans R Soc Lond B Biol Sci 2018; 372:rstb.2016.0359. [PMID: 28947658 PMCID: PMC5627161 DOI: 10.1098/rstb.2016.0359] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/14/2017] [Indexed: 11/12/2022] Open
Abstract
X chromosome inactivation (XCI) is a mechanism specifically initiated in female cells to silence one X chromosome, thereby equalizing the dose of X-linked gene products between male and female cells. XCI is regulated by a locus on the X chromosome termed the X-inactivation centre (XIC). Located within the XIC is XIST, which acts as a master regulator of XCI. During XCI, XIST is upregulated on the inactive X chromosome and chromosome-wide cis spreading of XIST leads to inactivation. In mouse, the Xic comprises Xist and all cis-regulatory elements and genes involved in Xist regulation. The activity of the XIC is regulated by trans-acting factors located elsewhere in the genome: X-encoded XCI activators positively regulating XCI, and autosomally encoded XCI inhibitors providing the threshold for XCI initiation. Whether human XCI is regulated through a similar mechanism, involving trans-regulatory factors acting on the XIC has remained elusive so far. Here, we describe a female individual with ovarian dysgenesis and a small X chromosomal deletion of the XIC. SNP-array and targeted locus amplification (TLA) analysis defined the deletion to a 1.28 megabase region, including XIST and all elements and genes that perform cis-regulatory functions in mouse XCI. Cells carrying this deletion still initiate XCI on the unaffected X chromosome, indicating that XCI can be initiated in the presence of only one XIC. Our results indicate that the trans-acting factors required for XCI initiation are located outside the deletion, providing evidence that the regulatory mechanisms of XCI are conserved between mouse and human. This article is part of the themed issue ‘X-chromosome inactivation: a tribute to Mary Lyon’.
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Affiliation(s)
- B de Hoon
- Department of Developmental Biology, Rotterdam, The Netherlands
| | | | - B Eussen
- Department of Clinical Genetics, Rotterdam, The Netherlands
| | - J C W Douben
- Department of Clinical Genetics, Rotterdam, The Netherlands
| | - E Rentmeester
- Department of Developmental Biology, Rotterdam, The Netherlands
| | | | - J S E Laven
- Department of Obstetrics and Gynaecology, Erasmus MC, Rotterdam, The Netherlands
| | | | - J Liebelt
- Division of Genetics and Molecular Pathology, Women's and Children's Hospital, North Adelaide, South Australia, Australia
| | - J Gribnau
- Department of Developmental Biology, Rotterdam, The Netherlands
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39
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Abstract
Marsupials and monotremes differ from eutherian mammals in many features of their reproduction and development. Some features appear to be representative of transitional stages in evolution from therapsid reptiles to humans and mice, particularly with respect to the extraembryonic tissues that have undergone remarkable modifications to accommodate reduced egg size and quantity of yolk/deutoplasm, and increasing emphasis on viviparity and placentation. Trophoblast and hypoblast contribute the epithelial layers in most of the extraembryonic membranes and are the first two lineages to differentiate from the embryonic lineage. How they are specified varies greatly among mammals, perhaps largely due to heterochrony in the stage at which they must function. Differences probably also exist in the stage at which lineages are specified relative to the stage at which they fully commit to differentiation. The dogma of sequential commitment to trophoblast and hypoblast with progressive loss of potency may not be a fundamental feature of early mammalian development, but merely a recently acquired developmental pattern in eutherians, or at least mice.
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40
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Veyrunes F, Perez J. X inactivation in a mammal species with three sex chromosomes. Chromosoma 2017; 127:261-267. [PMID: 29256059 DOI: 10.1007/s00412-017-0657-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Revised: 12/08/2017] [Accepted: 12/12/2017] [Indexed: 11/30/2022]
Abstract
X inactivation is a fundamental mechanism in eutherian mammals to restore a balance of X-linked gene products between XY males and XX females. However, it has never been extensively studied in a eutherian species with a sex determination system that deviates from the ubiquitous XX/XY. In this study, we explore the X inactivation process in the African pygmy mouse Mus minutoides, that harbours a polygenic sex determination with three sex chromosomes: Y, X, and a feminizing mutant X, named X*; females can thus be XX, XX*, or X*Y, and all males are XY. Using immunofluorescence, we investigated histone modification patterns between the two X chromosome types. We found that the X and X* chromosomes are randomly inactivated in XX* females, while no histone modifications were detected in X*Y females. Furthermore, in M. minutoides, X and X* chromosomes are fused to different autosomes, and we were able to show that the X inactivation never spreads into the autosomal segments. Evaluation of X inactivation by immunofluorescence is an excellent quantitative procedure, but it is only applicable when there is a structural difference between the two chromosomes that allows them to be distinguished.
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Affiliation(s)
- Frédéric Veyrunes
- Institut des Sciences de l'Evolution, ISEM UMR 5554 (CNRS / Université Montpellier / IRD / EPHE), Montpellier, France.
| | - Julie Perez
- Institut des Sciences de l'Evolution, ISEM UMR 5554 (CNRS / Université Montpellier / IRD / EPHE), Montpellier, France
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41
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Sakata Y, Nagao K, Hoki Y, Sasaki H, Obuse C, Sado T. Defects in dosage compensation impact global gene regulation in the mouse trophoblast. Development 2017; 144:2784-2797. [PMID: 28684628 DOI: 10.1242/dev.149138] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2017] [Accepted: 06/27/2017] [Indexed: 12/11/2022]
Abstract
Xist RNA, which is responsible for X inactivation, is a key epigenetic player in the embryogenesis of female mammals. Of the several repeats conserved in Xist RNA, the A-repeat has been shown to be essential for its silencing function in differentiating embryonic stem cells. Here, we introduced a new Xist allele into mouse that produces mutated Xist RNA lacking the A-repeat (XistCAGΔ5' ). XistCAGΔ5' RNA expressed in the embryo coated the X chromosome but failed to silence it. Although imprinted X inactivation was substantially compromised upon paternal transmission, allele-specific RNA-seq in the trophoblast revealed that XistCAGΔ5' RNA still retained some silencing ability. Furthermore, the failure of imprinted X inactivation had more significant impacts than expected on genome-wide gene expression. It is likely that dosage compensation is required not only for equalizing X-linked gene expression between the sexes but also for proper global gene regulation in differentiated female somatic cells.
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Affiliation(s)
- Yuka Sakata
- Department of Bioscience, Graduate School of Agriculture, Kindai University, 3327-204, Nakamachi, Nara 631-8505, Japan.,Division of Epigenomics, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Koji Nagao
- Graduate School of Life Science, Hokkaido University, Sapporo, Hokkaido 001-0021, Japan.,Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
| | - Yuko Hoki
- Division of Epigenomics, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Hiroyuki Sasaki
- Division of Epigenomics, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Chikashi Obuse
- Graduate School of Life Science, Hokkaido University, Sapporo, Hokkaido 001-0021, Japan.,Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
| | - Takashi Sado
- Department of Bioscience, Graduate School of Agriculture, Kindai University, 3327-204, Nakamachi, Nara 631-8505, Japan .,Division of Epigenomics, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
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42
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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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Yang T, Yildirim E. Epigenetic and LncRNA-Mediated Regulation of X Chromosome Inactivation and Its Impact on Pathogenesis. CURRENT PATHOBIOLOGY REPORTS 2017. [DOI: 10.1007/s40139-017-0120-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Dupont C, Maduro C, Den Braanker H, Boers R, Kurek D, Gribnau J. Characterization of Histone Modifications Associated with Inactive X-Chromosome in Trophoblast Stem Cells, eXtra-Embryonic Endoderm Cells and in In Vitro Derived Undifferentiated and Differentiated Epiblast Like Stem Cells. PLoS One 2016; 11:e0167154. [PMID: 27977710 PMCID: PMC5157996 DOI: 10.1371/journal.pone.0167154] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Accepted: 11/09/2016] [Indexed: 11/30/2022] Open
Abstract
In mouse, X-chromosome inactivation (XCI) can either be imprinted or random. Imprinted XCI (iXCI) is considered unstable and depending on continuous Xist expression, whereas random XCI (rXCI) is stably maintained even in the absence of Xist. Here we have systematically examined epigenetic modifications associated with the inactive X-chromosome (Xi) in Trophoblast Stem cells, eXtra-Embryonic Endoderm Cells, undifferentiated and differentiated Epiblast Like Stem Cells in order to understand intrinsic differences in epigenetic mechanisms involved in silencing of the inactive X-chromosome in lineages presenting iXCI and rXCI. Whereas euchromatic histone modifications are predominantly lost from the Xi territory in all cell types, the accumulation of heterochromatic modifications diverges in between the analysed cell lineages. Particularly, only the Xi of multipotent Trophoblast (iXCI) and Epiblast stem cells (rXCI) display a visible accumulation of Polycomb Repressive Complexes (PRCs), in contrast to the Xi in differentiated Epiblast Like Stem Cells and eXtra-embryonic Endoderm cells. Despite this, the histone modifications catalysed by PRCs, ubH2AK119 and H3K27me3, remain the best heterochromatic markers for the Xi in all assessed lineages. Heterochromatic chromatin modifications associated with the Xi are a reflection of the epigenetic landscape of the entire genome of the assessed cell regardless whether XCI is imprinted or random.
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Affiliation(s)
- Cathérine Dupont
- Erasmus MC, Department of Developmental Biology, Rotterdam, The Netherlands
| | - Cheryl Maduro
- Erasmus MC, Department of Developmental Biology, Rotterdam, The Netherlands
| | | | - Ruben Boers
- Erasmus MC, Department of Developmental Biology, Rotterdam, The Netherlands
| | - Dorota Kurek
- Erasmus MC, Department of Developmental Biology, Rotterdam, The Netherlands
| | - Joost Gribnau
- Erasmus MC, Department of Developmental Biology, Rotterdam, The Netherlands
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Abstract
X-chromosome inactivation, which was discovered by Mary Lyon in 1961 results in random silencing of one X chromosome in female mammals. This review is dedicated to Mary Lyon, who passed away last year. She predicted many of the features of X inactivation, for e.g., the existence of an X inactivation center, the role of L1 elements in spreading of silencing and the existence of genes that escape X inactivation. Starting from her published work here we summarize advances in the field.
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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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Goodrich L, Panning B, Leung KN. Activators and repressors: A balancing act for X-inactivation. Semin Cell Dev Biol 2016; 56:3-8. [DOI: 10.1016/j.semcdb.2016.05.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Revised: 05/06/2016] [Accepted: 05/06/2016] [Indexed: 10/21/2022]
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48
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Pinter SF. A Tale of Two Cities: How Xist and its partners localize to and silence the bicompartmental X. Semin Cell Dev Biol 2016; 56:19-34. [PMID: 27072488 DOI: 10.1016/j.semcdb.2016.03.023] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2016] [Revised: 03/30/2016] [Accepted: 03/30/2016] [Indexed: 10/22/2022]
Abstract
Sex chromosomal dosage compensation in mammals takes the form of X chromosome inactivation (XCI), driven by the non-coding RNA Xist. In contrast to dosage compensation systems of flies and worms, mammalian XCI has to restrict its function to the Xist-producing X chromosome, while leaving autosomes and active X untouched. The mechanisms behind the long-range yet cis-specific localization and silencing activities of Xist have long been enigmatic, but genomics, proteomics, super-resolution microscopy, and innovative genetic approaches have produced significant new insights in recent years. In this review, I summarize and integrate these findings with a particular focus on the redundant yet mutually reinforcing pathways that enable long-term transcriptional repression throughout the soma. This includes an exploration of concurrent epigenetic changes acting in parallel within two distinct compartments of the inactive X. I also examine how Polycomb repressive complexes 1 and 2 and macroH2A may bridge XCI establishment and maintenance. XCI is a remarkable phenomenon that operates across multiple scales, combining changes in nuclear architecture, chromosome topology, chromatin compaction, and nucleosome/nucleotide-level epigenetic cues. Learning how these pathways act in concert likely holds the answer to the riddle posed by Cattanach's and other autosomal translocations: What makes the X especially receptive to XCI?
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Affiliation(s)
- Stefan F Pinter
- Department of Genetics and Genome Sciences, Institute for Systems Genomics, University of Connecticut Health Center, 263 Farmington Ave, Farmington, CT 06030-6403, USA.
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Maduro C, de Hoon B, Gribnau J. Fitting the Puzzle Pieces: the Bigger Picture of XCI. Trends Biochem Sci 2016; 41:138-147. [DOI: 10.1016/j.tibs.2015.12.003] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Revised: 12/08/2015] [Accepted: 12/08/2015] [Indexed: 01/06/2023]
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Abstract
X-inactive specific transcript (Xist) long noncoding RNA (lncRNA) is thought to catalyze silencing of X-linked genes in cis during X-chromosome inactivation, which equalizes X-linked gene dosage between male and female mammals. To test the impact of Xist RNA on X-linked gene silencing, we ectopically induced endogenous Xist by ablating the antisense repressor Tsix in mice. We find that ectopic Xist RNA induction and subsequent X-linked gene silencing is sex specific in embryos and in differentiating embryonic stem cells (ESCs) and epiblast stem cells (EpiSCs). A higher frequency of X(ΔTsix)Y male cells displayed ectopic Xist RNA coating compared with X(ΔTsix)X female cells. This increase reflected the inability of X(ΔTsix)Y cells to efficiently silence X-linked genes compared with X(ΔTsix)X cells, despite equivalent Xist RNA induction and coating. Silencing of genes on both Xs resulted in significantly reduced proliferation and increased cell death in X(ΔTsix)X female cells relative to X(ΔTsix)Y male cells. Thus, whereas Xist RNA can inactivate the X chromosome in females it may not do so in males. We further found comparable silencing in differentiating X(ΔTsix)Y and 39,X(ΔTsix) (X(ΔTsix)O) ESCs, excluding the Y chromosome and instead implicating the X-chromosome dose as the source of the sex-specific differences. Because X(ΔTsix)X female embryonic epiblast cells and EpiSCs harbor an inactivated X chromosome prior to ectopic inactivation of the active X(ΔTsix) X chromosome, we propose that the increased expression of one or more X-inactivation escapees activates Xist and, separately, helps trigger X-linked gene silencing.
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