1
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Dror I, Tan T, Plath K. A critical role for X-chromosome architecture in mammalian X-chromosome dosage compensation. Curr Opin Genet Dev 2024; 87:102235. [PMID: 39053028 DOI: 10.1016/j.gde.2024.102235] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2024] [Revised: 07/02/2024] [Accepted: 07/05/2024] [Indexed: 07/27/2024]
Abstract
To regulate gene expression, the macromolecular components of the mammalian interphase nucleus are spatially organized into a myriad of functional compartments. Over the past decade, increasingly sophisticated genomics, microscopy, and functional approaches have probed this organization in unprecedented detail. These investigations have linked chromatin-associated noncoding RNAs to specific nuclear compartments and uncovered mechanisms by which these RNAs establish such domains. In this review, we focus on the long non-coding RNA Xist and summarize new evidence demonstrating the significance of chromatin reconfiguration in creating the inactive X-chromosome compartment. Differences in chromatin compaction correlate with distinct levels of gene repression on the X-chromosome, potentially explaining how human XIST can induce chromosome-wide dampening and silencing of gene expression at different stages of human development.
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Affiliation(s)
- Iris Dror
- Department of Biological Chemistry, David Geffen School of Medicine at the University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Tiao Tan
- Department of Biological Chemistry, David Geffen School of Medicine at the University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Kathrin Plath
- Department of Biological Chemistry, David Geffen School of Medicine at the University of California Los Angeles, Los Angeles, CA 90095, USA; Molecular Biology Institute, Jonsson Comprehensive Cancer Center, Brain Research Institute, Graduate Program in the Biosciences, Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, University of California Los Angeles, Los Angeles, CA 90095, USA.
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2
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Bansal P, Banda EC, Glatt-Deeley HR, Stoddard CE, Linsley JW, Arora N, Deleschaux C, Ahern DT, Kondaveeti Y, Massey RE, Nicouleau M, Wang S, Sabariego-Navarro M, Dierssen M, Finkbeiner S, Pinter SF. A dynamic in vitro model of Down syndrome neurogenesis with trisomy 21 gene dosage correction. SCIENCE ADVANCES 2024; 10:eadj0385. [PMID: 38848354 PMCID: PMC11160455 DOI: 10.1126/sciadv.adj0385] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2023] [Accepted: 05/03/2024] [Indexed: 06/09/2024]
Abstract
Excess gene dosage from chromosome 21 (chr21) causes Down syndrome (DS), spanning developmental and acute phenotypes in terminal cell types. Which phenotypes remain amenable to intervention after development is unknown. To address this question in a model of DS neurogenesis, we derived trisomy 21 (T21) human induced pluripotent stem cells (iPSCs) alongside, otherwise, isogenic euploid controls from mosaic DS fibroblasts and equipped one chr21 copy with an inducible XIST transgene. Monoallelic chr21 silencing by XIST is near-complete and irreversible in iPSCs. Differential expression reveals that T21 neural lineages and iPSCs share suppressed translation and mitochondrial pathways and activate cellular stress responses. When XIST is induced before the neural progenitor stage, T21 dosage correction suppresses a pronounced skew toward astrogenesis in neural differentiation. Because our transgene remains inducible in postmitotic T21 neurons and astrocytes, we demonstrate that XIST efficiently represses genes even after terminal differentiation, which will empower exploration of cell type-specific T21 phenotypes that remain responsive to chr21 dosage.
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Affiliation(s)
- Prakhar Bansal
- Graduate Program in Genetics and Developmental Biology, UCONN Health, University of Connecticut, Farmington, CT, USA
- Department of Genetics and Genome Sciences, UCONN Health, University of Connecticut, Farmington, CT, USA
| | - Erin C. Banda
- Department of Genetics and Genome Sciences, UCONN Health, University of Connecticut, Farmington, CT, USA
| | - Heather R. Glatt-Deeley
- Department of Genetics and Genome Sciences, UCONN Health, University of Connecticut, Farmington, CT, USA
| | - Christopher E. Stoddard
- Cell and Genome Engineering Core, UCONN Health, University of Connecticut, Farmington, CT, USA
| | - Jeremy W. Linsley
- Center for Systems and Therapeutics, Gladstone Institutes, San Francisco, CA, USA
- Taube/Koret Center for Neurodegenerative Disease, Gladstone Institutes, San Francisco, CA, USA
| | - Neha Arora
- Center for Systems and Therapeutics, Gladstone Institutes, San Francisco, CA, USA
| | - Cécile Deleschaux
- Department of Genetics and Genome Sciences, UCONN Health, University of Connecticut, Farmington, CT, USA
| | - Darcy T. Ahern
- Graduate Program in Genetics and Developmental Biology, UCONN Health, University of Connecticut, Farmington, CT, USA
- Department of Genetics and Genome Sciences, UCONN Health, University of Connecticut, Farmington, CT, USA
| | - Yuvabharath Kondaveeti
- Department of Genetics and Genome Sciences, UCONN Health, University of Connecticut, Farmington, CT, USA
| | - Rachael E. Massey
- Graduate Program in Genetics and Developmental Biology, UCONN Health, University of Connecticut, Farmington, CT, USA
- Department of Genetics and Genome Sciences, UCONN Health, University of Connecticut, Farmington, CT, USA
- Institute for Systems Genomics, University of Connecticut, Farmington, CT, USA
| | - Michael Nicouleau
- Department of Genetics and Genome Sciences, UCONN Health, University of Connecticut, Farmington, CT, USA
| | - Shijie Wang
- Center for Systems and Therapeutics, Gladstone Institutes, San Francisco, CA, USA
| | - Miguel Sabariego-Navarro
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Barcelona, Spain
| | - Mara Dierssen
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Barcelona, Spain
- Universitat Pompeu Fabra (UPF), Barcelona, Spain
- Human Pharmacology and Clinical Neurosciences Research Group, Neurosciences Research Program, Hospital Del Mar Medical Research Institute (IMIM), Barcelona, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain
| | - Steven Finkbeiner
- Center for Systems and Therapeutics, Gladstone Institutes, San Francisco, CA, USA
- Taube/Koret Center for Neurodegenerative Disease, Gladstone Institutes, San Francisco, CA, USA
- Departments of Neurology and Physiology, University of California San Francisco, San Francisco, CA, USA
- Neuroscience and Biomedical Sciences Graduate Programs, University of California San Francisco, San Francisco, CA, USA
| | - Stefan F. Pinter
- Graduate Program in Genetics and Developmental Biology, UCONN Health, University of Connecticut, Farmington, CT, USA
- Department of Genetics and Genome Sciences, UCONN Health, University of Connecticut, Farmington, CT, USA
- Institute for Systems Genomics, University of Connecticut, Farmington, CT, USA
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3
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Ferrer J, Dimitrova N. Transcription regulation by long non-coding RNAs: mechanisms and disease relevance. Nat Rev Mol Cell Biol 2024; 25:396-415. [PMID: 38242953 PMCID: PMC11045326 DOI: 10.1038/s41580-023-00694-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/11/2023] [Indexed: 01/21/2024]
Abstract
Long non-coding RNAs (lncRNAs) outnumber protein-coding transcripts, but their functions remain largely unknown. In this Review, we discuss the emerging roles of lncRNAs in the control of gene transcription. Some of the best characterized lncRNAs have essential transcription cis-regulatory functions that cannot be easily accomplished by DNA-interacting transcription factors, such as XIST, which controls X-chromosome inactivation, or imprinted lncRNAs that direct allele-specific repression. A growing number of lncRNA transcription units, including CHASERR, PVT1 and HASTER (also known as HNF1A-AS1) act as transcription-stabilizing elements that fine-tune the activity of dosage-sensitive genes that encode transcription factors. Genetic experiments have shown that defects in such transcription stabilizers often cause severe phenotypes. Other lncRNAs, such as lincRNA-p21 (also known as Trp53cor1) and Maenli (Gm29348) contribute to local activation of gene transcription, whereas distinct lncRNAs influence gene transcription in trans. We discuss findings of lncRNAs that elicit a function through either activation of their transcription, transcript elongation and processing or the lncRNA molecule itself. We also discuss emerging evidence of lncRNA involvement in human diseases, and their potential as therapeutic targets.
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Affiliation(s)
- Jorge Ferrer
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology (BIST), Barcelona, Spain.
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Madrid, Spain.
- Department of Metabolism, Digestion and Reproduction, Imperial College London, London, UK.
| | - Nadya Dimitrova
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT, USA.
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4
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Hauth A, Panten J, Kneuss E, Picard C, Servant N, Rall I, Pérez-Rico YA, Clerquin L, Servaas N, Villacorta L, Jung F, Luong C, Chang HY, Zaugg JB, Stegle O, Odom DT, Loda A, Heard E. Escape from X inactivation is directly modulated by levels of Xist non-coding RNA. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.22.581559. [PMID: 38559194 PMCID: PMC10979913 DOI: 10.1101/2024.02.22.581559] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
In placental females, one copy of the two X chromosomes is largely silenced during a narrow developmental time window, in a process mediated by the non-coding RNA Xist1. Here, we demonstrate that Xist can initiate X-chromosome inactivation (XCI) well beyond early embryogenesis. By modifying its endogenous level, we show that Xist has the capacity to actively silence genes that escape XCI both in neuronal progenitor cells (NPCs) and in vivo, in mouse embryos. We also show that Xist plays a direct role in eliminating TAD-like structures associated with clusters of escapee genes on the inactive X chromosome, and that this is dependent on Xist's XCI initiation partner, SPEN2. We further demonstrate that Xist's function in suppressing gene expression of escapees and topological domain formation is reversible for up to seven days post-induction, but that sustained Xist up-regulation leads to progressively irreversible silencing and CpG island DNA methylation of facultative escapees. Thus, the distinctive transcriptional and regulatory topologies of the silenced X chromosome is actively, directly - and reversibly - controlled by Xist RNA throughout life.
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Affiliation(s)
- Antonia Hauth
- European Molecular Biology Laboratory, Directors' Research, 69117 Heidelberg, Germany
- Collaboration for joint PhD degree between EMBL and Heidelberg University, Germany
| | - Jasper Panten
- Division of Regulatory Genomics and Cancer Evolution, German Cancer Research Centre (DKFZ), 69120, Heidelberg, Germany
- Division of Computational Genomics and Systems Genetics, German Cancer Research Centre (DKFZ), 69120, Heidelberg, Germany
- Faculty of Biosciences, Heidelberg University, 69117, Heidelberg, Germany
| | - Emma Kneuss
- European Molecular Biology Laboratory, Directors' Research, 69117 Heidelberg, Germany
| | - Christel Picard
- European Molecular Biology Laboratory, Directors' Research, 69117 Heidelberg, Germany
- Present address: Institute of Molecular Genetics of Montpellier University of Montpellier, CNRS, 34090 Montpellier, France
| | - Nicolas Servant
- Bioinformatics and Computational Systems Biology of Cancer, INSERM U900, Paris 75005, France
| | - Isabell Rall
- European Molecular Biology Laboratory, Directors' Research, 69117 Heidelberg, Germany
- Present address: Institute of Human Biology (IHB), Roche Innovation Center Basel, 4070 Basel, Switzerland
| | - Yuvia A Pérez-Rico
- European Molecular Biology Laboratory, Directors' Research, 69117 Heidelberg, Germany
| | - Lena Clerquin
- European Molecular Biology Laboratory, Directors' Research, 69117 Heidelberg, Germany
| | - Nila Servaas
- European Molecular Biology Laboratory, Structural and Computational Biology Unit, 69117 Heidelberg, Germany
| | - Laura Villacorta
- European Molecular Biology Laboratory, Genomics Core Facility, 69117 Heidelberg, Germany
| | - Ferris Jung
- European Molecular Biology Laboratory, Genomics Core Facility, 69117 Heidelberg, Germany
| | - Christy Luong
- Center for Personal Dynamic Regulomes, Stanford University, Stanford, CA 94305, USA
| | - Howard Y Chang
- Center for Personal Dynamic Regulomes, Stanford University, Stanford, CA 94305, USA
- Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - Judith B Zaugg
- European Molecular Biology Laboratory, Structural and Computational Biology Unit, 69117 Heidelberg, Germany
- Molecular Medicine Partnership Unit, EMBL-University of Heidelberg, Heidelberg, Germany
| | - Oliver Stegle
- European Molecular Biology Laboratory, Genome Biology Unit, 69117 Heidelberg, Germany
- Division of Computational Genomics and Systems Genetics, German Cancer Research Centre (DKFZ), 69120, Heidelberg, Germany
| | - Duncan T Odom
- Division of Regulatory Genomics and Cancer Evolution, German Cancer Research Centre (DKFZ), 69120, Heidelberg, Germany
- Faculty of Biosciences, Heidelberg University, 69117, Heidelberg, Germany
- Cancer Research UK Cambridge Institute, University of Cambridge, Cambridge, UK
| | - Agnese Loda
- European Molecular Biology Laboratory, Directors' Research, 69117 Heidelberg, Germany
| | - Edith Heard
- European Molecular Biology Laboratory, Directors' Research, 69117 Heidelberg, Germany
- Collège de France, Paris 75005, France
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5
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Gupta K, Czerminski JT, Lawrence JB. Trisomy silencing by XIST: translational prospects and challenges. Hum Genet 2024:10.1007/s00439-024-02651-8. [PMID: 38459355 DOI: 10.1007/s00439-024-02651-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Accepted: 01/25/2024] [Indexed: 03/10/2024]
Abstract
XIST RNA is heavily studied for its role in fundamental epigenetics and X-chromosome inactivation; however, the translational potential of this singular RNA has been much less explored. This article combines elements of a review on XIST biology with our perspective on the translational prospects and challenges of XIST transgenics. We first briefly review aspects of XIST RNA basic biology that are key to its translational relevance, and then discuss recent efforts to develop translational utility of XIST for chromosome dosage disorders, particularly Down syndrome (DS). Remarkably, it was shown in vitro that expression of an XIST transgene inserted into one chromosome 21 can comprehensively silence that chromosome and "dosage compensate" Trisomy 21, the cause of DS. Here we summarize recent findings and discuss potential paths whereby ability to induce "trisomy silencing" can advance translational research for new therapeutic strategies. Despite its common nature, the underlying biology for various aspects of DS, including cell types and pathways impacted (and when), is poorly understood. Recent studies show that an inducible iPSC system to dosage-correct chromosome 21 can provide a powerful approach to unravel the cells and pathways directly impacted, and the developmental timing, information key to design pharmacotherapeutics. In addition, we discuss prospects of a more far-reaching and challenging possibility that XIST itself could be developed into a therapeutic agent, for targeted cellular "chromosome therapy". A few rare case studies of imbalanced X;autosome translocations indicate that natural XIST can rescue an otherwise lethal trisomy. The potential efficacy of XIST transgenes later in development faces substantial biological and technical challenges, although recent findings are encouraging, and technology is rapidly evolving. Hence, it is compelling to consider the transformative possibility that XIST-mediated chromosome therapy may ultimately be developed, for specific pathologies seen in DS, or other duplication disorders.
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Affiliation(s)
- Khusali Gupta
- Department of Neurology, University of Massachusetts Chan Medical School, Worcester, MA, 01655, USA
| | - Jan T Czerminski
- Department of Neurology, University of Massachusetts Chan Medical School, Worcester, MA, 01655, USA
- Medical Scientist Training Program, University of Massachusetts Chan Medical School, Worcester, MA, 01655, USA
| | - Jeanne B Lawrence
- Department of Neurology, University of Massachusetts Chan Medical School, Worcester, MA, 01655, USA.
- Department of Pediatrics, University of Massachusetts Chan Medical School, Worcester, MA, 01655, USA.
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6
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Dror I, Chitiashvili T, Tan SYX, Cano CT, Sahakyan A, Markaki Y, Chronis C, Collier AJ, Deng W, Liang G, Sun Y, Afasizheva A, Miller J, Xiao W, Black DL, Ding F, Plath K. XIST directly regulates X-linked and autosomal genes in naive human pluripotent cells. Cell 2024; 187:110-129.e31. [PMID: 38181737 PMCID: PMC10783549 DOI: 10.1016/j.cell.2023.11.033] [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] [Received: 12/21/2020] [Revised: 04/01/2023] [Accepted: 11/28/2023] [Indexed: 01/07/2024]
Abstract
X chromosome inactivation (XCI) serves as a paradigm for RNA-mediated regulation of gene expression, wherein the long non-coding RNA XIST spreads across the X chromosome in cis to mediate gene silencing chromosome-wide. In female naive human pluripotent stem cells (hPSCs), XIST is in a dispersed configuration, and XCI does not occur, raising questions about XIST's function. We found that XIST spreads across the X chromosome and induces dampening of X-linked gene expression in naive hPSCs. Surprisingly, XIST also targets specific autosomal regions, where it induces repressive chromatin changes and gene expression dampening. Thereby, XIST equalizes X-linked gene dosage between male and female cells while inducing differences in autosomes. The dispersed Xist configuration and autosomal localization also occur transiently during XCI initiation in mouse PSCs. Together, our study identifies XIST as the regulator of X chromosome dampening, uncovers an evolutionarily conserved trans-acting role of XIST/Xist, and reveals a correlation between XIST/Xist dispersal and autosomal targeting.
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Affiliation(s)
- Iris Dror
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Tsotne Chitiashvili
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Shawn Y X Tan
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Clara T Cano
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Anna Sahakyan
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Yolanda Markaki
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA; Institute for Structural and Chemical Biology & Department of Molecular and Cell Biology, University of Leicester, Leicester LE1 7RH, UK
| | - Constantinos Chronis
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA; Department of Biochemistry and Molecular Genetics, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Amanda J Collier
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Weixian Deng
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Guohao Liang
- Department of Biomedical Engineering, University of California Irvine, Irvine, CA 92697, USA
| | - Yu Sun
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Anna Afasizheva
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Jarrett Miller
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Wen Xiao
- Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Douglas L Black
- Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Fangyuan Ding
- Department of Biomedical Engineering, University of California Irvine, Irvine, CA 92697, USA; Department of Developmental and Cell Biology, Department of Pharmaceutical Sciences, University of California Irvine, Irvine, CA 92697, USA
| | - Kathrin Plath
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA.
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7
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Abstract
The eukaryotic nucleus displays a variety of membraneless compartments with distinct biomolecular composition and specific cellular activities. Emerging evidence indicates that protein-based liquid-liquid phase separation (LLPS) plays an essential role in the formation and dynamic regulation of heterochromatin compartmentalization. This feature is especially conspicuous at the pericentric heterochromatin domains. In this review, we will describe our understanding of heterochromatin organization and LLPS. In addition, we will highlight the increasing importance of multivalent weak homo- and heteromolecular interactions in LLPS-mediated heterochromatin compartmentalization in the complex environment inside living cells.
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Affiliation(s)
- Hui Zhang
- Cell Biology and Epigenetics, Department of Biology, Technical University of Darmstadt, Darmstadt, Germany
| | - Weihua Qin
- Human Biology and Bioimaging, Faculty of Biology, Ludwig Maximilians University Munich, Planegg-Martinsried, Germany
| | - Hector Romero
- Cell Biology and Epigenetics, Department of Biology, Technical University of Darmstadt, Darmstadt, Germany
| | - Heinrich Leonhardt
- Human Biology and Bioimaging, Faculty of Biology, Ludwig Maximilians University Munich, Planegg-Martinsried, Germany
| | - M. Cristina Cardoso
- Cell Biology and Epigenetics, Department of Biology, Technical University of Darmstadt, Darmstadt, Germany,CONTACT M. Cristina Cardoso Cell Biology and Epigenetics, Department of Biology, Technical University of Darmstadt, Schnittspahnstr. 10, 64287Darmstadt, Germany
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8
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Keniry A, Blewitt ME. Chromatin-mediated silencing on the inactive X chromosome. Development 2023; 150:dev201742. [PMID: 37991053 DOI: 10.1242/dev.201742] [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: 11/23/2023]
Abstract
In mammals, the second X chromosome in females is silenced to enable dosage compensation between XX females and XY males. This essential process involves the formation of a dense chromatin state on the inactive X (Xi) chromosome. There is a wealth of information about the hallmarks of Xi chromatin and the contribution each makes to silencing, leaving the tantalising possibility of learning from this knowledge to potentially remove silencing to treat X-linked diseases in females. Here, we discuss the role of each chromatin feature in the establishment and maintenance of the silent state, which is of crucial relevance for such a goal.
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Affiliation(s)
- Andrew Keniry
- Epigenetics and Development Division, The Walter and Eliza Hall Institute for Medical Research, 1G Royal Parade, Parkville, VIC 3052, Australia
- The Department of Medical Biology, University of Melbourne, Parkville, VIC 3010, Australia
| | - Marnie E Blewitt
- Epigenetics and Development Division, The Walter and Eliza Hall Institute for Medical Research, 1G Royal Parade, Parkville, VIC 3052, Australia
- The Department of Medical Biology, University of Melbourne, Parkville, VIC 3010, Australia
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9
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Valledor M, Byron M, Dumas B, Carone DM, Hall LL, Lawrence JB. Early chromosome condensation by XIST builds A-repeat RNA density that facilitates gene silencing. Cell Rep 2023; 42:112686. [PMID: 37384527 PMCID: PMC10461597 DOI: 10.1016/j.celrep.2023.112686] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Revised: 10/31/2022] [Accepted: 06/08/2023] [Indexed: 07/01/2023] Open
Abstract
XIST RNA triggers chromosome-wide gene silencing and condenses an active chromosome into a Barr body. Here, we use inducible human XIST to examine early steps in the process, showing that XIST modifies cytoarchitecture before widespread gene silencing. In just 2-4 h, barely visible transcripts populate the large "sparse zone" surrounding the smaller "dense zone"; importantly, density zones exhibit different chromatin impacts. Sparse transcripts immediately trigger immunofluorescence for H2AK119ub and CIZ1, a matrix protein. H3K27me3 appears hours later in the dense zone, which enlarges with chromosome condensation. Genes examined are silenced after compaction of the RNA/DNA territory. Insights into this come from the findings that the A-repeat alone can silence genes and rapidly, but only where dense RNA supports sustained histone deacetylation. We propose that sparse XIST RNA quickly impacts architectural elements to condense the largely non-coding chromosome, coalescing RNA density that facilitates an unstable, A-repeat-dependent step required for gene silencing.
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Affiliation(s)
- Melvys Valledor
- Department of Neurology, University of Massachusetts Chan Medical School, Worcester, MA 01655, USA
| | - Meg Byron
- Department of Neurology, University of Massachusetts Chan Medical School, Worcester, MA 01655, USA
| | - Brett Dumas
- Department of Medicine, Boston University Medical Center, Boston, MA 02118, USA
| | - Dawn M Carone
- Department of Biology, Swarthmore College, Swarthmore, PA 19081, USA
| | - Lisa L Hall
- Department of Neurology, University of Massachusetts Chan Medical School, Worcester, MA 01655, USA.
| | - Jeanne B Lawrence
- Department of Neurology, University of Massachusetts Chan Medical School, Worcester, MA 01655, USA; Department of Pediatrics, University of Massachusetts Chan Medical School, Worcester, MA 01655, USA.
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10
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Segal D, Dostie J. The Talented LncRNAs: Meshing into Transcriptional Regulatory Networks in Cancer. Cancers (Basel) 2023; 15:3433. [PMID: 37444543 DOI: 10.3390/cancers15133433] [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: 05/25/2023] [Revised: 06/22/2023] [Accepted: 06/23/2023] [Indexed: 07/15/2023] Open
Abstract
As a group of diseases characterized by uncontrollable cell growth, cancer is highly multifaceted in how it overrides checkpoints controlling proliferation. Amongst the regulators of these checkpoints, long non-coding RNAs (lncRNAs) can have key roles in why natural biological processes go haywire. LncRNAs represent a large class of regulatory transcripts that can localize anywhere in cells. They were found to affect gene expression on many levels from transcription to mRNA translation and even protein stability. LncRNA participation in such control mechanisms can depend on cell context, with given transcripts sometimes acting as oncogenes or tumor suppressors. Importantly, the tissue-specificity and low expression levels of lncRNAs make them attractive therapeutic targets or biomarkers. Here, we review the various cellular processes affected by lncRNAs and outline molecular strategies they use to control gene expression, particularly in cancer and in relation to transcription factors.
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Affiliation(s)
- Dana Segal
- Department of Biochemistry, McGill University, Montréal, QC H3G 1Y6, Canada
- Rosalind and Morris Goodman Cancer Institute, McGill University, Montréal, QC H3A 1A3, Canada
| | - Josée Dostie
- Department of Biochemistry, McGill University, Montréal, QC H3G 1Y6, Canada
- Rosalind and Morris Goodman Cancer Institute, McGill University, Montréal, QC H3A 1A3, Canada
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11
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Jali I, Vanamamalai VK, Garg P, Navarrete P, Gutiérrez-Adán A, Sharma S. Identification and differential expression of long non-coding RNAs and their association with XIST gene during early embryonic developmental stages of Bos taurus. Int J Biol Macromol 2023; 229:896-908. [PMID: 36572076 DOI: 10.1016/j.ijbiomac.2022.12.221] [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: 07/25/2022] [Revised: 10/07/2022] [Accepted: 12/20/2022] [Indexed: 12/26/2022]
Abstract
X-chromosomes inactivation (XCI) is a phenomenon that aims to equalize the dosage of X-linked gene products between XY males and XX females in mammals. XIST gene is the master regulator of X chromosome inactivation during early embryonic developmental stages of Bos taurus. Biological molecule such as lncRNA plays significant role in the control of XCI, by RNA-based regulatory mechanisms and are non-coding regions of the genome. In our study, using in-silico transcriptome data analysis approach, we analysed RNA-seq data of E35, E39 and E43 samples from bovine genital ridges of early embryonic stages, and identified lncRNA transcripts. More than 7 lakh lncRNA transcripts were identified. Further, our study identified DE-lncRNAs and genes between male and female and studied their co-expression. More than four thousand differentially expressed lncRNAs identified. The co-expression and RT-PCR study in the result showed that there exists an association between the XIST and DE-lncRNAs in early embryonic gonads of bovine at E35. In this study, the association between DE-lncRNAs and XIST gene indicates, the potentially important role of DE-lncRNAs during embryo development in bovine. In conclusion, this study shows there exist an interplay between genes and lncRNAs at transcriptome level of bovine during early embryonic days.
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Affiliation(s)
- Itishree Jali
- National Institute of Animal Biotechnology (NIAB), Opp. Journalist Colony, Near Gowlidoddi, Extended Q City Road, Gachibowli, Hyderabad 500 032, Telangana, India; DBT-Regional Centre for Biotechnology (RCB), Faridabad 121001, Haryana, India
| | - Venkata Krishna Vanamamalai
- National Institute of Animal Biotechnology (NIAB), Opp. Journalist Colony, Near Gowlidoddi, Extended Q City Road, Gachibowli, Hyderabad 500 032, Telangana, India; DBT-Regional Centre for Biotechnology (RCB), Faridabad 121001, Haryana, India
| | - Priyanka Garg
- National Institute of Animal Biotechnology (NIAB), Opp. Journalist Colony, Near Gowlidoddi, Extended Q City Road, Gachibowli, Hyderabad 500 032, Telangana, India
| | - Paula Navarrete
- INIA-CSIC Centro Nacional Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA)-Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
| | - Alfonso Gutiérrez-Adán
- INIA-CSIC Centro Nacional Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA)-Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
| | - Shailesh Sharma
- National Institute of Animal Biotechnology (NIAB), Opp. Journalist Colony, Near Gowlidoddi, Extended Q City Road, Gachibowli, Hyderabad 500 032, Telangana, India; DBT-Regional Centre for Biotechnology (RCB), Faridabad 121001, Haryana, India.
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12
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Shevchenko AI, Rifel NA, Zakian SM, Zakharova IS. Constitutive heterochromatin propagation contributes to the X chromosome inactivation. Chromosome Res 2022; 30:289-307. [PMID: 35920963 DOI: 10.1007/s10577-022-09706-4] [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: 04/27/2022] [Revised: 07/08/2022] [Accepted: 07/15/2022] [Indexed: 01/25/2023]
Abstract
Imprinted X chromosome inactivation (iXCI) balances the expression of X-linked genes in preimplantation embryos and extraembryonic tissues in rodents. Long noncoding Xist RNA drives iXCI, silencing genes and recruiting Xist-dependent chromatin repressors. Some domains on the inactive X chromosome include repressive modifications specific to constitutive heterochromatin, which show no direct link to Xist RNA. We explored the relationship between Xist RNA and chromatin silencing during iXCI in vole Microtus levis. We performed locus-specific activation of Xist transcription on the only active X chromosome using the dCas9-SAM system in XO vole trophoblast stem cells (TSCs), which allow modeling iXCI events to some extent. The artificially activated endogenous vole Xist transcript is truncated and restricted ~ 6.6 kb of the exon 1. Ectopic Xist RNA accumulates on the X chromosome and recruits Xist-dependent modifications during TSC differentiation, yet is incapable by itself repressing X-linked genes. Transcriptional silencing occurs upon ectopic Xist upregulation only when repressive marks spread from the massive telomeric constitutive heterochromatin to the X chromosome region containing genes. We hypothesize that the Xist RNA-induced propagation of repressive marks from the constitutive heterochromatin could be a mechanism involved in X chromosome inactivation.
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Affiliation(s)
- Alexander I Shevchenko
- Federal Research Center, "Institute of Cytology and Genetics of the Siberian Branch of the Russian Academy of Sciences", Novosibirsk, 630090, Russia.,Institute of Chemical Biology and Fundamental Medicine of the Siberian Branch of the Russian Academy of Sciences, Novosibirsk, 630090, Russia.,E.N. Meshalkin National Medical Research Center, Ministry of Health Care of Russian Federation, Novosibirsk, 630055, Russia
| | - Nikita A Rifel
- Federal Research Center, "Institute of Cytology and Genetics of the Siberian Branch of the Russian Academy of Sciences", Novosibirsk, 630090, Russia
| | - Suren M Zakian
- Federal Research Center, "Institute of Cytology and Genetics of the Siberian Branch of the Russian Academy of Sciences", Novosibirsk, 630090, Russia.,Institute of Chemical Biology and Fundamental Medicine of the Siberian Branch of the Russian Academy of Sciences, Novosibirsk, 630090, Russia.,E.N. Meshalkin National Medical Research Center, Ministry of Health Care of Russian Federation, Novosibirsk, 630055, Russia
| | - Irina S Zakharova
- Federal Research Center, "Institute of Cytology and Genetics of the Siberian Branch of the Russian Academy of Sciences", Novosibirsk, 630090, Russia. .,Institute of Chemical Biology and Fundamental Medicine of the Siberian Branch of the Russian Academy of Sciences, Novosibirsk, 630090, Russia. .,E.N. Meshalkin National Medical Research Center, Ministry of Health Care of Russian Federation, Novosibirsk, 630055, Russia.
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13
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Grimm NB, Lee JT. Selective Xi reactivation and alternative methods to restore MECP2 function in Rett syndrome. Trends Genet 2022; 38:920-943. [PMID: 35248405 PMCID: PMC9915138 DOI: 10.1016/j.tig.2022.01.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 01/15/2022] [Accepted: 01/19/2022] [Indexed: 10/19/2022]
Abstract
The human X-chromosome harbors only 4% of our genome but carries over 20% of genes associated with intellectual disability. Given that they inherit only one X-chromosome, males are more frequently affected by X-linked neurodevelopmental genetic disorders than females. However, despite inheriting two X-chromosomes, females can also be affected because X-chromosome inactivation enables only one of two X-chromosomes to be expressed per cell. For Rett syndrome and similar X-linked disorders affecting females, disease-specific treatments have remained elusive. However, a cure may be found within their own cells because every sick cell carries a healthy copy of the affected gene on the inactive X (Xi). Therefore, selective Xi reactivation may be a viable approach that would address the root cause of various X-linked disorders. Here, we discuss Rett syndrome and compare current approaches in the pharmaceutical pipeline to restore MECP2 function. We then focus on Xi reactivation and review available methods, lessons learned, and future directions.
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Affiliation(s)
- Niklas-Benedikt Grimm
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA, USA; Department of Genetics, The Blavatnik Institute, Harvard Medical School, Boston, MA, USA; Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Barcelona, Spain; Universitat Pompeu Fabra (UPF), Barcelona, Spain
| | - Jeannie T Lee
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA, USA; Department of Genetics, The Blavatnik Institute, Harvard Medical School, Boston, MA, USA.
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14
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Wanigasuriya I, Kinkel SA, Beck T, Roper EA, Breslin K, Lee HJ, Keniry A, Ritchie ME, Blewitt ME, Gouil Q. Maternal SMCHD1 controls both imprinted Xist expression and imprinted X chromosome inactivation. Epigenetics Chromatin 2022; 15:26. [PMID: 35843975 PMCID: PMC9290310 DOI: 10.1186/s13072-022-00458-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Accepted: 06/21/2022] [Indexed: 12/13/2022] Open
Abstract
Embryonic development is dependent on the maternal supply of proteins through the oocyte, including factors setting up the adequate epigenetic patterning of the zygotic genome. We previously reported that one such factor is the epigenetic repressor SMCHD1, whose maternal supply controls autosomal imprinted expression in mouse preimplantation embryos and mid-gestation placenta. In mouse preimplantation embryos, X chromosome inactivation is also an imprinted process. Combining genomics and imaging, we show that maternal SMCHD1 is required not only for the imprinted expression of Xist in preimplantation embryos, but also for the efficient silencing of the inactive X in both the preimplantation embryo and mid-gestation placenta. These results expand the role of SMCHD1 in enforcing the silencing of Polycomb targets. The inability of zygotic SMCHD1 to fully restore imprinted X inactivation further points to maternal SMCHD1’s role in setting up the appropriate chromatin environment during preimplantation development, a critical window of epigenetic remodelling.
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Affiliation(s)
- Iromi Wanigasuriya
- Walter and Eliza Hall Institute of Medical Research, Parkville, Australia.,The Department of Medical Biology, The University of Melbourne, Parkville, Australia
| | - Sarah A Kinkel
- Walter and Eliza Hall Institute of Medical Research, Parkville, Australia.,The Department of Medical Biology, The University of Melbourne, Parkville, Australia
| | - Tamara Beck
- Walter and Eliza Hall Institute of Medical Research, Parkville, Australia.,The Department of Medical Biology, The University of Melbourne, Parkville, Australia
| | - Ellise A Roper
- The School of Biomedical Sciences and Pharmacy, The University of Newcastle, Newcastle, Australia
| | - Kelsey Breslin
- Walter and Eliza Hall Institute of Medical Research, Parkville, Australia.,The Department of Medical Biology, The University of Melbourne, Parkville, Australia
| | - Heather J Lee
- The School of Biomedical Sciences and Pharmacy, The University of Newcastle, Newcastle, Australia
| | - Andrew Keniry
- Walter and Eliza Hall Institute of Medical Research, Parkville, Australia.,The Department of Medical Biology, The University of Melbourne, Parkville, Australia
| | - Matthew E Ritchie
- Walter and Eliza Hall Institute of Medical Research, Parkville, Australia.,The Department of Medical Biology, The University of Melbourne, Parkville, Australia.,The Department of Mathematics and Statistics, The University of Melbourne, Parkville, Australia
| | - Marnie E Blewitt
- Walter and Eliza Hall Institute of Medical Research, Parkville, Australia. .,The Department of Medical Biology, The University of Melbourne, Parkville, Australia.
| | - Quentin Gouil
- Walter and Eliza Hall Institute of Medical Research, Parkville, Australia. .,The Department of Medical Biology, The University of Melbourne, Parkville, Australia.
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15
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A lifelong duty: how Xist maintains the inactive X chromosome. Curr Opin Genet Dev 2022; 75:101927. [PMID: 35717799 PMCID: PMC9472561 DOI: 10.1016/j.gde.2022.101927] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Revised: 05/10/2022] [Accepted: 05/14/2022] [Indexed: 11/22/2022]
Abstract
Female eutherians transcriptionally silence one X chromosome to balance gene dosage between the sexes. X-chromosome inactivation (XCI) is initiated by the lncRNA Xist, which assembles many proteins within the inactive X chromosome (Xi) to trigger gene silencing and heterochromatin formation. It is well established that gene silencing on the Xi is maintained through repressive epigenetic processes, including histone deacetylation and DNA methylation. Recent studies revealed a new mechanism where RNA-binding proteins that interact directly with the RNA contribute to the maintenance of Xist localization and gene silencing. In addition, a surprising plasticity of the Xi was uncovered with many genes becoming upregulated upon experimental deletion of Xist. Intriguingly, immune cells normally lose Xist from the Xi, suggesting that thisXist dependence is utilized in vivo to dynamically regulate gene expression from the Xi. These new studies expose fundamental regulatory mechanisms for the chromatin association of RNAs, highlight the need for studying the maintenance of XCI and Xist localization in a gene- and cell-type-specific manner, and are likely to have clinical impact.
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16
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XIST loss impairs mammary stem cell differentiation and increases tumorigenicity through Mediator hyperactivation. Cell 2022; 185:2164-2183.e25. [PMID: 35597241 DOI: 10.1016/j.cell.2022.04.034] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Revised: 01/10/2022] [Accepted: 04/27/2022] [Indexed: 12/27/2022]
Abstract
X inactivation (XCI) is triggered by upregulation of XIST, which coats the chromosome in cis, promoting formation of a heterochromatic domain (Xi). XIST role beyond initiation of XCI is only beginning to be elucidated. Here, we demonstrate that XIST loss impairs differentiation of human mammary stem cells (MaSCs) and promotes emergence of highly tumorigenic and metastatic carcinomas. On the Xi, XIST deficiency triggers epigenetic changes and reactivation of genes overlapping Polycomb domains, including Mediator subunit MED14. MED14 overdosage results in increased Mediator levels and hyperactivation of the MaSC enhancer landscape and transcriptional program, making differentiation less favorable. We further demonstrate that loss of XIST and Xi transcriptional instability is common among human breast tumors of poor prognosis. We conclude that XIST is a gatekeeper of human mammary epithelium homeostasis, thus unveiling a paradigm in the control of somatic cell identity with potential consequences for our understanding of gender-specific malignancies.
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17
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Abstract
It has long been proposed that nuclear RNAs might play an important role in organizing the structure of the nucleus. Initial experiments performed more than 30 years ago found that global disruption of RNA led to visible rearrangements of nuclear organization. Yet, this idea remained controversial for many years, in large part because it was unclear what specific RNAs might be involved, and which specific nuclear structures might be dependent on RNA. Over the past few years, the contributions of RNA to organizing nuclear structures have become clearer with the discovery that many nuclear bodies are enriched for specific noncoding RNAs (ncRNAs); in specific cases, ncRNAs have been shown to be essential for establishment and maintenance of these nuclear structures. More recently, many different ncRNAs have been shown to play critical roles in initiating the three-dimensional (3D) spatial organization of DNA, RNA, and protein molecules in the nucleus. These examples, combined with global imaging and genomic experiments, have begun to paint a picture of a broader role for RNA in nuclear organization and to uncover a unifying mechanism that may explain why RNA is a uniquely suited molecule for this role. In this review, we provide an overview of the history of RNA and nuclear structure and discuss key examples of RNA-mediated bodies, the global roles of ncRNAs in shaping nuclear structure, and emerging insights into mechanisms of RNA-mediated nuclear organization.
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Affiliation(s)
- Sofia A Quinodoz
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125, USA
| | - Mitchell Guttman
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125, USA
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18
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Substoichiometric action of long noncoding RNAs. Nat Cell Biol 2022; 24:608-615. [PMID: 35562482 DOI: 10.1038/s41556-022-00911-1] [Citation(s) in RCA: 27] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Accepted: 04/01/2022] [Indexed: 11/08/2022]
Abstract
Low expression levels and stoichiometric imbalances of long noncoding RNAs (lncRNAs) are often used as evidence for their probable lack of function or for limiting the scope of their potential influence. Recent advances in our understanding of the substoichiometric functions of lncRNAs challenge these notions and suggest routes through which unabundant lncRNAs can affect cellular functions and gene regulatory networks.
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19
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Sofi S, Williamson L, Turvey GL, Scoynes C, Hirst C, Godwin J, Brockdorff N, Ainscough J, Coverley D. Prion-like domains drive CIZ1 assembly formation at the inactive X chromosome. J Biophys Biochem Cytol 2022; 221:213067. [PMID: 35289833 PMCID: PMC8927971 DOI: 10.1083/jcb.202103185] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 11/11/2021] [Accepted: 12/10/2021] [Indexed: 12/30/2022] Open
Abstract
CIZ1 forms large assemblies at the inactive X chromosome (Xi) in female fibroblasts in an Xist lncRNA-dependent manner and is required for accurate maintenance of polycomb targets genome-wide. Here we address requirements for assembly formation and show that CIZ1 undergoes two direct interactions with Xist, via independent N- and C-terminal domains. Interaction with Xist, assembly at Xi, and complexity of self-assemblies formed in vitro are modulated by two alternatively spliced glutamine-rich prion-like domains (PLD1 and 2). PLD2 is dispensable for accumulation at existing CIZ1-Xi assemblies in wild-type cells but is required in CIZ1-null cells where targeting, assembly, and enrichment for H3K27me3 and H2AK119ub occur de novo. In contrast, PLD1 is required for both de novo assembly and accumulation at preexisting assemblies and, in vitro, drives formation of a stable fibrillar network. Together they impart affinity for RNA and a complex relationship with repeat E of Xist. These data show that alternative splicing of two PLDs modulates CIZ1's ability to build large RNA-protein assemblies.
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Affiliation(s)
- Sajad Sofi
- Department of Biology, University of York, York, UK.,York Biomedical Research Institute, University of York, York, UK
| | - Louisa Williamson
- Department of Biology, University of York, York, UK.,York Biomedical Research Institute, University of York, York, UK
| | - Gabrielle L Turvey
- Department of Biology, University of York, York, UK.,York Biomedical Research Institute, University of York, York, UK
| | - Charlotte Scoynes
- Department of Biology, University of York, York, UK.,College of Science and Engineering, University of Edinburgh, Edinburgh, UK
| | - Claire Hirst
- Department of Biology, University of York, York, UK
| | - Jonathan Godwin
- Department of Biochemistry, University of Oxford, Oxford, UK
| | - Neil Brockdorff
- Department of Biochemistry, University of Oxford, Oxford, UK
| | - Justin Ainscough
- Department of Biology, University of York, York, UK.,York Biomedical Research Institute, University of York, York, UK
| | - Dawn Coverley
- Department of Biology, University of York, York, UK.,York Biomedical Research Institute, University of York, York, UK
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20
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From genotype to phenotype: genetics of mammalian long non-coding RNAs in vivo. Nat Rev Genet 2022; 23:229-243. [PMID: 34837040 DOI: 10.1038/s41576-021-00427-8] [Citation(s) in RCA: 48] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/15/2021] [Indexed: 12/14/2022]
Abstract
Genome-wide sequencing has led to the discovery of thousands of long non-coding RNA (lncRNA) loci in the human genome, but evidence of functional significance has remained controversial for many lncRNAs. Genetically engineered model organisms are considered the gold standard for linking genotype to phenotype. Recent advances in CRISPR-Cas genome editing have led to a rapid increase in the use of mouse models to more readily survey lncRNAs for functional significance. Here, we review strategies to investigate the physiological relevance of lncRNA loci by highlighting studies that have used genetic mouse models to reveal key in vivo roles for lncRNAs, from fertility to brain development. We illustrate how an investigative approach, starting with whole-gene deletion followed by transcription termination and/or transgene rescue strategies, can provide definitive evidence for the in vivo function of mammalian lncRNAs.
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21
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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: 20] [Impact Index Per Article: 10.0] [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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22
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Di Minin G, Holzner M, Grison A, Dumeau CE, Chan W, Monfort A, Jerome-Majewska LA, Roelink H, Wutz A. TMED2 binding restricts SMO to the ER and Golgi compartments. PLoS Biol 2022; 20:e3001596. [PMID: 35353806 PMCID: PMC9000059 DOI: 10.1371/journal.pbio.3001596] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Revised: 04/11/2022] [Accepted: 03/07/2022] [Indexed: 11/30/2022] Open
Abstract
Hedgehog (HH) signaling is important for embryonic pattering and stem cell differentiation. The G protein–coupled receptor (GPCR) Smoothened (SMO) is the key HH signal transducer modulating both transcription-dependent and transcription-independent responses. We show that SMO protects naive mouse embryonic stem cells (ESCs) from dissociation-induced cell death. We exploited this SMO dependency to perform a genetic screen in haploid ESCs where we identify the Golgi proteins TMED2 and TMED10 as factors for SMO regulation. Super-resolution microscopy shows that SMO is normally retained in the endoplasmic reticulum (ER) and Golgi compartments, and we demonstrate that TMED2 binds to SMO, preventing localization to the plasma membrane. Mutation of TMED2 allows SMO accumulation at the plasma membrane, recapitulating early events after HH stimulation. We demonstrate the physiologic relevance of this interaction in neural differentiation, where TMED2 functions to repress HH signal strength. Identification of TMED2 as a binder and upstream regulator of SMO opens the way for unraveling the events in the ER–Golgi leading to HH signaling activation. Hedgehog signals orchestrate tissue patterning by binding the receptor Patched and restricting the signal transducer Smoothened. A genetic screen reveals Tmed2 as a new interactor of Smoothened that is required for regulating Smoothened transport from the endoplasmic reticulum and Golgi to the plasma membrane and hence modulating the strength of Hedgehog signal transduction.
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Affiliation(s)
- Giulio Di Minin
- Institute of Molecular Health Sciences, Department of Biology, Swiss Federal Institute of Technology ETH Hönggerberg, Zurich, Switzerland
- * E-mail: (GDM); (AW)
| | - Markus Holzner
- Institute of Molecular Health Sciences, Department of Biology, Swiss Federal Institute of Technology ETH Hönggerberg, Zurich, Switzerland
| | - Alice Grison
- Department of Biomedicine, University of Basel, Basel, Switzerland
| | - Charles E. Dumeau
- Institute of Molecular Health Sciences, Department of Biology, Swiss Federal Institute of Technology ETH Hönggerberg, Zurich, Switzerland
| | - Wesley Chan
- Department Anatomy and Cell Biology, Human Genetics and McGill University, Montreal, Canada
- Department of Pediatrics, Human Genetics and McGill University, Montreal, Canada
| | - Asun Monfort
- Institute of Molecular Health Sciences, Department of Biology, Swiss Federal Institute of Technology ETH Hönggerberg, Zurich, Switzerland
| | - Loydie A. Jerome-Majewska
- Department Anatomy and Cell Biology, Human Genetics and McGill University, Montreal, Canada
- Department of Pediatrics, Human Genetics and McGill University, Montreal, Canada
| | - Henk Roelink
- Department of Molecular and Cell Biology, University of California, Berkeley, California, United States of America
| | - Anton Wutz
- Institute of Molecular Health Sciences, Department of Biology, Swiss Federal Institute of Technology ETH Hönggerberg, Zurich, Switzerland
- * E-mail: (GDM); (AW)
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23
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BAF complex-mediated chromatin relaxation is required for establishment of X chromosome inactivation. Nat Commun 2022; 13:1658. [PMID: 35351876 PMCID: PMC8964718 DOI: 10.1038/s41467-022-29333-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2021] [Accepted: 03/10/2022] [Indexed: 12/12/2022] Open
Abstract
The process of epigenetic silencing, while fundamentally important, is not yet completely understood. Here we report a replenishable female mouse embryonic stem cell (mESC) system, Xmas, that allows rapid assessment of X chromosome inactivation (XCI), the epigenetic silencing mechanism of one of the two X chromosomes that enables dosage compensation in female mammals. Through a targeted genetic screen in differentiating Xmas mESCs, we reveal that the BAF complex is required to create nucleosome-depleted regions at promoters on the inactive X chromosome during the earliest stages of establishment of XCI. Without this action gene silencing fails. Xmas mESCs provide a tractable model for screen-based approaches that enable the discovery of unknown facets of the female-specific process of XCI and epigenetic silencing more broadly. Female embryonic stem cells (ESCs) are the ideal model to study X chromosome inactivation (XCI) establishment; however, these cells are challenging to keep in culture. Here the authors create fluorescent ‘Xmas’ reporter mice as a renewable source of ESCs and show nucleosome remodelers Smarcc1 and Smarca4 create a nucleosome-free promoter region prior to the establishment of silencing.
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24
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Florini F, Visone JE, Deitsch KW. Shared Mechanisms for Mutually Exclusive Expression and Antigenic Variation by Protozoan Parasites. Front Cell Dev Biol 2022; 10:852239. [PMID: 35350381 PMCID: PMC8957917 DOI: 10.3389/fcell.2022.852239] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Accepted: 02/17/2022] [Indexed: 01/05/2023] Open
Abstract
Cellular decision-making at the level of gene expression is a key process in the development and evolution of every organism. Variations in gene expression can lead to phenotypic diversity and the development of subpopulations with adaptive advantages. A prime example is the mutually exclusive activation of a single gene from within a multicopy gene family. In mammals, this ranges from the activation of one of the two immunoglobulin (Ig) alleles to the choice in olfactory sensory neurons of a single odorant receptor (OR) gene from a family of more than 1,000. Similarly, in parasites like Trypanosoma brucei, Giardia lamblia or Plasmodium falciparum, the process of antigenic variation required to escape recognition by the host immune system involves the monoallelic expression of vsg, vsp or var genes, respectively. Despite the importance of this process, understanding how this choice is made remains an enigma. The development of powerful techniques such as single cell RNA-seq and Hi-C has provided new insights into the mechanisms these different systems employ to achieve monoallelic gene expression. Studies utilizing these techniques have shown how the complex interplay between nuclear architecture, physical interactions between chromosomes and different chromatin states lead to single allele expression. Additionally, in several instances it has been observed that high-level expression of a single gene is preceded by a transient state where multiple genes are expressed at a low level. In this review, we will describe and compare the different strategies that organisms have evolved to choose one gene from within a large family and how parasites employ this strategy to ensure survival within their hosts.
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25
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Xist spatially amplifies SHARP/SPEN recruitment to balance chromosome-wide silencing and specificity to the X chromosome. Nat Struct Mol Biol 2022; 29:239-249. [PMID: 35301492 DOI: 10.1038/s41594-022-00739-1] [Citation(s) in RCA: 45] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Accepted: 01/28/2022] [Indexed: 11/08/2022]
Abstract
Although thousands of long non-coding RNAs (lncRNAs) are encoded in mammalian genomes, their mechanisms of action are poorly understood, in part because they are often expressed at lower levels than their proposed targets. One such lncRNA is Xist, which mediates chromosome-wide gene silencing on one of the two X chromosomes (X) to achieve gene expression balance between males and females. How a limited number of Xist molecules can mediate robust silencing of a much larger number of target genes while maintaining specificity exclusively to genes on the X within each cell is not well understood. Here, we show that Xist drives non-stoichiometric recruitment of the essential silencing protein SHARP (also known as SPEN) to amplify its abundance across the inactive X, including at regions not directly occupied by Xist. This amplification is achieved through concentration-dependent homotypic assemblies of SHARP on the X and is required for chromosome-wide silencing. Expression of Xist at higher levels leads to increased localization at autosomal regions, demonstrating that low levels of Xist are critical for ensuring its specificity to the X. We show that Xist (through SHARP) acts to suppress production of its own RNA which may act to constrain overall RNA levels and restrict its ability to spread beyond the X. Together, our results demonstrate a spatial amplification mechanism that allows Xist to achieve two essential but countervailing regulatory objectives: chromosome-wide gene silencing and specificity to the X. This suggests a more general mechanism by which other low-abundance lncRNAs could balance specificity to, and robust control of, their regulatory targets.
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26
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Carlini V, Policarpi C, Hackett JA. Epigenetic inheritance is gated by naïve pluripotency and Dppa2. EMBO J 2022; 41:e108677. [PMID: 35199868 PMCID: PMC8982627 DOI: 10.15252/embj.2021108677] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2021] [Revised: 01/12/2022] [Accepted: 01/17/2022] [Indexed: 12/14/2022] Open
Abstract
Environmental factors can trigger cellular responses that propagate across mitosis or even generations. Perturbations to the epigenome could underpin such acquired changes, however, the extent and contexts in which modified chromatin states confer heritable memory in mammals is unclear. Here, we exploit a precision epigenetic editing strategy and forced Xist activity to programme de novo heterochromatin domains (epialleles) at endogenous loci and track their inheritance in a developmental model. We find that naïve pluripotent phases systematically erase ectopic domains of heterochromatin via active mechanisms, which likely acts as an intergenerational safeguard against transmission of epialleles. Upon lineage specification, however, acquired chromatin states can be probabilistically inherited under selectively favourable conditions, including propagation of p53 silencing through in vivo development. Using genome‐wide CRISPR screening, we identify molecular factors that restrict heritable memory of epialleles in naïve pluripotent cells, and demonstrate that removal of chromatin factor Dppa2 unlocks the potential for epigenetic inheritance uncoupled from DNA sequence. Our study outlines a mechanistic basis for how epigenetic inheritance is constrained in mammals, and reveals genomic and developmental contexts in which heritable memory is feasible.
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Affiliation(s)
- Valentina Carlini
- Epigenetics & Neurobiology Unit, European Molecular Biology Laboratory (EMBL), Rome, Italy.,Faculty of Biosciences, Collaboration for Joint PhD Degree between EMBL and Heidelberg University, Heidelberg, Germany
| | - Cristina Policarpi
- Epigenetics & Neurobiology Unit, European Molecular Biology Laboratory (EMBL), Rome, Italy
| | - Jamie A Hackett
- Epigenetics & Neurobiology Unit, European Molecular Biology Laboratory (EMBL), Rome, Italy
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27
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Camilleri-Robles C, Amador R, Klein CC, Guigó R, Corominas M, Ruiz-Romero M. Genomic and functional conservation of lncRNAs: lessons from flies. Mamm Genome 2022; 33:328-342. [PMID: 35098341 PMCID: PMC9114055 DOI: 10.1007/s00335-021-09939-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Accepted: 12/09/2021] [Indexed: 12/18/2022]
Abstract
Over the last decade, the increasing interest in long non-coding RNAs (lncRNAs) has led to the discovery of these transcripts in multiple organisms. LncRNAs tend to be specifically, and often lowly, expressed in certain tissues, cell types and biological contexts. Although lncRNAs participate in the regulation of a wide variety of biological processes, including development and disease, most of their functions and mechanisms of action remain unknown. Poor conservation of the DNA sequences encoding for these transcripts makes the identification of lncRNAs orthologues among different species very challenging, especially between evolutionarily distant species such as flies and humans or mice. However, the functions of lncRNAs are unexpectedly preserved among different species supporting the idea that conservation occurs beyond DNA sequences and reinforcing the potential of characterising lncRNAs in animal models. In this review, we describe the features and roles of lncRNAs in the fruit fly Drosophila melanogaster, focusing on genomic and functional comparisons with human and mouse lncRNAs. We also discuss the current state of advances and limitations in the study of lncRNA conservation and future perspectives.
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28
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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: 83] [Impact Index Per Article: 41.5] [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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29
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X-chromosome reactivation: a concise review. Biochem Soc Trans 2021; 49:2797-2805. [PMID: 34821360 DOI: 10.1042/bst20210777] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Revised: 11/03/2021] [Accepted: 11/05/2021] [Indexed: 12/14/2022]
Abstract
Mammalian females (XX) silence transcription on one of the two X chromosomes to compensate the expression dosage with males (XY). This process - named X-chromosome inactivation - entails a variety of epigenetic modifications that act synergistically to maintain silencing and make it heritable through cell divisions. Genes along the inactive X chromosome are, indeed, refractory to reactivation. Nonetheless, X-chromosome reactivation can occur alongside with epigenome reprogramming or by perturbing multiple silencing pathways. Here we review the events associated with X-chromosome reactivation during in vivo and in vitro reprogramming and highlight recent efforts in inducing Xi reactivation by molecular perturbations. This provides us with a first understanding of the mechanisms underlying X-chromosome reactivation, which could be tackled for therapeutic purposes.
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30
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Xist nucleates local protein gradients to propagate silencing across the X chromosome. Cell 2021; 184:6174-6192.e32. [PMID: 34813726 PMCID: PMC8671326 DOI: 10.1016/j.cell.2021.10.022] [Citation(s) in RCA: 47] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Revised: 07/29/2021] [Accepted: 10/11/2021] [Indexed: 02/08/2023]
Abstract
The lncRNA Xist forms ∼50 diffraction-limited foci to transcriptionally silence one X chromosome. How this small number of RNA foci and interacting proteins regulate a much larger number of X-linked genes is unknown. We show that Xist foci are locally confined, contain ∼2 RNA molecules, and nucleate supramolecular complexes (SMACs) that include many copies of the critical silencing protein SPEN. Aggregation and exchange of SMAC proteins generate local protein gradients that regulate broad, proximal chromatin regions. Partitioning of numerous SPEN molecules into SMACs is mediated by their intrinsically disordered regions and essential for transcriptional repression. Polycomb deposition via SMACs induces chromatin compaction and the increase in SMACs density around genes, which propagates silencing across the X chromosome. Our findings introduce a mechanism for functional nuclear compartmentalization whereby crowding of transcriptional and architectural regulators enables the silencing of many target genes by few RNA molecules.
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31
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Loh CH, van Genesen S, Perino M, Bark MR, Veenstra GJC. Loss of PRC2 subunits primes lineage choice during exit of pluripotency. Nat Commun 2021; 12:6985. [PMID: 34848733 PMCID: PMC8632979 DOI: 10.1038/s41467-021-27314-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2020] [Accepted: 11/09/2021] [Indexed: 12/11/2022] Open
Abstract
Polycomb Repressive Complex 2 (PRC2) is crucial for the coordinated expression of genes during early embryonic development, catalyzing histone H3 lysine 27 trimethylation. Two distinct PRC2 complexes, PRC2.1 and PRC2.2, contain respectively MTF2 and JARID2 in embryonic stem cells (ESCs). In this study, we explored their roles in lineage specification and commitment, using single-cell transcriptomics and mouse embryoid bodies derived from Mtf2 and Jarid2 null ESCs. We observe that the loss of Mtf2 results in enhanced and faster differentiation towards cell fates from all germ layers, while the Jarid2 null cells are predominantly directed towards early differentiating precursors, with reduced efficiency towards mesendodermal lineages. These effects are caused by derepression of developmental regulators that are poised for activation in pluripotent cells and gain H3K4me3 at their promoters in the absence of PRC2 repression. Upon lineage commitment, the differentiation trajectories are relatively similar to those of wild-type cells. Together, our results uncover a major role for MTF2-containing PRC2.1 in balancing poised lineage-specific gene activation, whereas the contribution of JARID2-containing PRC2 is more selective in nature compared to MTF2. These data explain how PRC2 imposes thresholds for lineage choice during the exit of pluripotency.
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Affiliation(s)
- Chet H. Loh
- grid.5590.90000000122931605Department of Molecular Developmental Biology, Faculty of Science, Radboud Institute for Molecular Life Sciences, Radboud University, Nijmegen, The Netherlands
| | - Siebe van Genesen
- grid.5590.90000000122931605Department of Molecular Developmental Biology, Faculty of Science, Radboud Institute for Molecular Life Sciences, Radboud University, Nijmegen, The Netherlands
| | - Matteo Perino
- grid.5590.90000000122931605Department of Molecular Developmental Biology, Faculty of Science, Radboud Institute for Molecular Life Sciences, Radboud University, Nijmegen, The Netherlands ,grid.4709.a0000 0004 0495 846XPresent Address: Genome Biology Unit, European Molecular Biology Laboratory (EMBL), Heidelberg, Germany
| | - Magnus R. Bark
- grid.5590.90000000122931605Department of Molecular Developmental Biology, Faculty of Science, Radboud Institute for Molecular Life Sciences, Radboud University, Nijmegen, The Netherlands
| | - Gert Jan C. Veenstra
- grid.5590.90000000122931605Department of Molecular Developmental Biology, Faculty of Science, Radboud Institute for Molecular Life Sciences, Radboud University, Nijmegen, The Netherlands
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32
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Enervald E, Powell LM, Boteva L, Foti R, Blanes Ruiz N, Kibar G, Piszczek A, Cavaleri F, Vingron M, Cerase A, Buonomo SBC. RIF1 and KAP1 differentially regulate the choice of inactive versus active X chromosomes. EMBO J 2021; 40:e105862. [PMID: 34786738 DOI: 10.15252/embj.2020105862] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2020] [Revised: 10/05/2021] [Accepted: 10/19/2021] [Indexed: 11/09/2022] Open
Abstract
The onset of random X chromosome inactivation in mouse requires the switch from a symmetric to an asymmetric state, where the identities of the future inactive and active X chromosomes are assigned. This process is known as X chromosome choice. Here, we show that RIF1 and KAP1 are two fundamental factors for the definition of this transcriptional asymmetry. We found that at the onset of differentiation of mouse embryonic stem cells (mESCs), biallelic up-regulation of the long non-coding RNA Tsix weakens the symmetric association of RIF1 with the Xist promoter. The Xist allele maintaining the association with RIF1 goes on to up-regulate Xist RNA expression in a RIF1-dependent manner. Conversely, the promoter that loses RIF1 gains binding of KAP1, and KAP1 is required for the increase in Tsix levels preceding the choice. We propose that the mutual exclusion of Tsix and RIF1, and of RIF1 and KAP1, at the Xist promoters establish a self-sustaining loop that transforms an initially stochastic event into a stably inherited asymmetric X-chromosome state.
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Affiliation(s)
- Elin Enervald
- Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, UK.,Epigenetics & Neurobiology Unit, European Molecular Biology Laboratory (EMBL Rome), Monterotondo, Italy
| | - Lynn Marie Powell
- Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, UK
| | - Lora Boteva
- Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, UK
| | - Rossana Foti
- Epigenetics & Neurobiology Unit, European Molecular Biology Laboratory (EMBL Rome), Monterotondo, Italy
| | - Nerea Blanes Ruiz
- Blizard Institute, Centre for Genomics and Child Health, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Gözde Kibar
- Max-Planck-Institut fuer molekulare Genetik, Berlin, Germany
| | - Agnieszka Piszczek
- Epigenetics & Neurobiology Unit, European Molecular Biology Laboratory (EMBL Rome), Monterotondo, Italy
| | - Fatima Cavaleri
- Epigenetics & Neurobiology Unit, European Molecular Biology Laboratory (EMBL Rome), Monterotondo, Italy
| | - Martin Vingron
- Max-Planck-Institut fuer molekulare Genetik, Berlin, Germany
| | - Andrea Cerase
- Blizard Institute, Centre for Genomics and Child Health, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Sara B C Buonomo
- Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, UK.,Epigenetics & Neurobiology Unit, European Molecular Biology Laboratory (EMBL Rome), Monterotondo, Italy
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33
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Trigiante G, Blanes Ruiz N, Cerase A. Emerging Roles of Repetitive and Repeat-Containing RNA in Nuclear and Chromatin Organization and Gene Expression. Front Cell Dev Biol 2021; 9:735527. [PMID: 34722514 PMCID: PMC8552494 DOI: 10.3389/fcell.2021.735527] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Accepted: 09/09/2021] [Indexed: 12/14/2022] Open
Abstract
Genomic repeats have been intensely studied as regulatory elements controlling gene transcription, splicing and genome architecture. Our understanding of the role of the repetitive RNA such as the RNA coming from genomic repeats, or repetitive sequences embedded in mRNA/lncRNAs, in nuclear and cellular functions is instead still limited. In this review we discuss evidence supporting the multifaceted roles of repetitive RNA and RNA binding proteins in nuclear organization, gene regulation, and in the formation of dynamic membrane-less aggregates. We hope that our review will further stimulate research in the consolidating field of repetitive RNA biology.
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Affiliation(s)
| | | | - Andrea Cerase
- Centre for Genomics and Child Health, Barts and The London School of Medicine and Dentistry, Blizard Institute, Queen Mary University of London, London, United Kingdom
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34
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Nuclear compartmentalization as a mechanism of quantitative control of gene expression. Nat Rev Mol Cell Biol 2021; 22:653-670. [PMID: 34341548 DOI: 10.1038/s41580-021-00387-1] [Citation(s) in RCA: 115] [Impact Index Per Article: 38.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/28/2021] [Indexed: 01/08/2023]
Abstract
Gene regulation requires the dynamic coordination of hundreds of regulatory factors at precise genomic and RNA targets. Although many regulatory factors have specific affinity for their nucleic acid targets, molecular diffusion and affinity models alone cannot explain many of the quantitative features of gene regulation in the nucleus. One emerging explanation for these quantitative properties is that DNA, RNA and proteins organize within precise, 3D compartments in the nucleus to concentrate groups of functionally related molecules. Recently, nucleic acids and proteins involved in many important nuclear processes have been shown to engage in cooperative interactions, which lead to the formation of condensates that partition the nucleus. In this Review, we discuss an emerging perspective of gene regulation, which moves away from classic models of stoichiometric interactions towards an understanding of how spatial compartmentalization can lead to non-stoichiometric molecular interactions and non-linear regulatory behaviours. We describe key mechanisms of nuclear compartment formation, including emerging roles for non-coding RNAs in facilitating their formation, and discuss the functional role of nuclear compartments in transcription regulation, co-transcriptional and post-transcriptional RNA processing, and higher-order chromatin regulation. More generally, we discuss how compartmentalization may explain important quantitative aspects of gene regulation.
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35
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Tamura Y, Ohhata T, Niida H, Sakai S, Uchida C, Masumoto K, Katou F, Wutz A, Kitagawa M. Homologous recombination is reduced in female embryonic stem cells by two active X chromosomes. EMBO Rep 2021; 22:e52190. [PMID: 34309165 DOI: 10.15252/embr.202052190] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2020] [Revised: 06/21/2021] [Accepted: 06/22/2021] [Indexed: 12/16/2022] Open
Abstract
The reactivation of X-linked genes is observed in some primary breast tumors. Two active X chromosomes are also observed in female embryonic stem cells (ESCs), but whether double doses of X-linked genes affect DNA repair efficiency remains unclear. Here, we establish isogenic female/male ESCs and show that the female ESCs are more sensitive to camptothecin and have lower gene targeting efficiency than male ESCs, suggesting that homologous recombination (HR) efficiency is reduced in female ESCs. We also generate Xist-inducible female ESCs and show that the lower HR efficiency is restored when X chromosome inactivation is induced. Finally, we assess the X-linked genes with a role in DNA repair and find that Brcc3 is one of the genes involved in a network promoting proper HR. Our findings link the double doses of X-linked genes with lower DNA repair activity, and this may have relevance for common diseases in female patients, such as breast cancer.
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Affiliation(s)
- Yuka Tamura
- Department of Molecular Biology, Hamamatsu University School of Medicine, Hamamatsu, Japan.,Department of Oral and Maxillofacial Surgery, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Tatsuya Ohhata
- Department of Molecular Biology, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Hiroyuki Niida
- Department of Molecular Biology, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Satoshi Sakai
- Department of Molecular Biology, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Chiharu Uchida
- Advanced Research Facilities & Services, Preeminent Medical Photonics Education & Research Center, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Kazuma Masumoto
- Department of Oral and Maxillofacial Surgery, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Fuminori Katou
- Department of Oral and Maxillofacial Surgery, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Anton Wutz
- Institute of Molecular Health Sciences, ETH Zürich, Zurich, Switzerland
| | - Masatoshi Kitagawa
- Department of Molecular Biology, Hamamatsu University School of Medicine, Hamamatsu, Japan
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36
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A Novel cis Regulatory Element Regulates Human XIST in a CTCF-Dependent Manner. Mol Cell Biol 2021; 41:e0038220. [PMID: 34060915 DOI: 10.1128/mcb.00382-20] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
The long noncoding RNA XIST is the master regulator for the process of X chromosome inactivation (XCI) in mammalian females. Here, we report the existence of a hitherto-uncharacterized cis regulatory element (cRE) within the first exon of human XIST, which determines the transcriptional status of XIST during the initiation and maintenance phases of XCI. In the initiation phase, pluripotency factors bind to this cRE and keep XIST repressed. In the maintenance phase of XCI, the cRE is enriched for CTCF, which activates XIST transcription. By employing a CRISPR-dCas9-KRAB-based interference strategy, we demonstrate that binding of CTCF to the newly identified cRE is critical for regulating XIST in a YY1-dependent manner. Collectively, our study uncovers the combinatorial effect of multiple transcriptional regulators influencing XIST expression during the initiation and maintenance phases of XCI.
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37
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Rodermund L, Coker H, Oldenkamp R, Wei G, Bowness J, Rajkumar B, Nesterova T, Susano Pinto DM, Schermelleh L, Brockdorff N. Time-resolved structured illumination microscopy reveals key principles of Xist RNA spreading. Science 2021; 372:372/6547/eabe7500. [PMID: 34112668 DOI: 10.1126/science.abe7500] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Accepted: 05/07/2021] [Indexed: 01/23/2023]
Abstract
X-inactive specific transcript (Xist) RNA directs the process of X chromosome inactivation in mammals by spreading in cis along the chromosome from which it is transcribed and recruiting chromatin modifiers to silence gene transcription. To elucidate mechanisms of Xist RNA cis-confinement, we established a sequential dual-color labeling, super-resolution imaging approach to trace individual Xist RNA molecules over time, which enabled us to define fundamental parameters of spreading. We demonstrate a feedback mechanism linking Xist RNA synthesis and degradation and an unexpected physical coupling between preceding and newly synthesized Xist RNA molecules. Additionally, we find that the protein SPEN, a key factor for Xist-mediated gene silencing, has a distinct function in Xist RNA localization, stability, and coupling behaviors. Our results provide insights toward understanding the distinct dynamic properties of Xist RNA.
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Affiliation(s)
- Lisa Rodermund
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
| | - Heather Coker
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
| | - Roel Oldenkamp
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
| | - Guifeng Wei
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
| | - Joseph Bowness
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
| | - Bramman Rajkumar
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
| | - Tatyana Nesterova
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
| | | | | | - Neil Brockdorff
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK.
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38
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Kawatani K, Nambara T, Nawa N, Yoshimatsu H, Kusakabe H, Hirata K, Tanave A, Sumiyama K, Banno K, Taniguchi H, Arahori H, Ozono K, Kitabatake Y. A human isogenic iPSC-derived cell line panel identifies major regulators of aberrant astrocyte proliferation in Down syndrome. Commun Biol 2021; 4:730. [PMID: 34127780 PMCID: PMC8203796 DOI: 10.1038/s42003-021-02242-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Accepted: 05/18/2021] [Indexed: 12/15/2022] Open
Abstract
Astrocytes exert adverse effects on the brains of individuals with Down syndrome (DS). Although a neurogenic-to-gliogenic shift in the fate-specification step has been reported, the mechanisms and key regulators underlying the accelerated proliferation of astrocyte precursor cells (APCs) in DS remain elusive. Here, we established a human isogenic cell line panel based on DS-specific induced pluripotent stem cells, the XIST-mediated transcriptional silencing system in trisomic chromosome 21, and genome/chromosome-editing technologies to eliminate phenotypic fluctuations caused by genetic variation. The transcriptional responses of genes observed upon XIST induction and/or downregulation are not uniform, and only a small subset of genes show a characteristic expression pattern, which is consistent with the proliferative phenotypes of DS APCs. Comparative analysis and experimental verification using gene modification reveal dose-dependent proliferation-promoting activity of DYRK1A and PIGP on DS APCs. Our collection of human isogenic cell lines provides a comprehensive set of cellular models for further DS investigations. Keiji Kawatani et al. developed a panel of Down syndrome (DS) isogenic astrocytes derived from iPSCs to observe the consequence of DS on astrocyte precursor proliferation, differentiation, and gene expression. Their results suggest a dose-dependent effect of DYRK1A and PIGP on DS-derived astrocyte precursor proliferation, and represent a valuable resource and cellular model for future DS research.
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Affiliation(s)
- Keiji Kawatani
- Department of Pediatrics, Graduate School of Medicine, Osaka University, Suita, Osaka, Japan
| | - Toshihiko Nambara
- Department of Pediatrics, Graduate School of Medicine, Osaka University, Suita, Osaka, Japan
| | - Nobutoshi Nawa
- Department of Pediatrics, Graduate School of Medicine, Osaka University, Suita, Osaka, Japan
| | - Hidetaka Yoshimatsu
- Department of Pediatrics, Graduate School of Medicine, Osaka University, Suita, Osaka, Japan
| | - Haruna Kusakabe
- Department of Pediatrics, Graduate School of Medicine, Osaka University, Suita, Osaka, Japan
| | - Katsuya Hirata
- Department of Pediatrics, Graduate School of Medicine, Osaka University, Suita, Osaka, Japan.,Department of Neonatal Medicine, Osaka Women's and Children's Hospital, Izumi, Osaka, Japan
| | - Akira Tanave
- Laboratory for Mouse Genetic Engineering, RIKEN Center for Biosystems Dynamics Research, Suita, Osaka, Japan
| | - Kenta Sumiyama
- Laboratory for Mouse Genetic Engineering, RIKEN Center for Biosystems Dynamics Research, Suita, Osaka, Japan
| | - Kimihiko Banno
- Department of Pediatrics, Graduate School of Medicine, Osaka University, Suita, Osaka, Japan.,Department of Physiology II, Nara Medical University, Kashihara, Nara, Japan
| | - Hidetoshi Taniguchi
- Department of Pediatrics, Graduate School of Medicine, Osaka University, Suita, Osaka, Japan
| | - Hitomi Arahori
- Department of Pediatrics, Graduate School of Medicine, Osaka University, Suita, Osaka, Japan
| | - Keiichi Ozono
- Department of Pediatrics, Graduate School of Medicine, Osaka University, Suita, Osaka, Japan
| | - Yasuji Kitabatake
- Department of Pediatrics, Graduate School of Medicine, Osaka University, Suita, Osaka, Japan.
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39
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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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40
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Bansal P, Ahern DT, Kondaveeti Y, Qiu CW, Pinter SF. Contiguous erosion of the inactive X in human pluripotency concludes with global DNA hypomethylation. Cell Rep 2021; 35:109215. [PMID: 34107261 PMCID: PMC8267460 DOI: 10.1016/j.celrep.2021.109215] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Revised: 08/18/2020] [Accepted: 05/13/2021] [Indexed: 01/21/2023] Open
Abstract
Female human pluripotent stem cells (hPSCs) routinely undergo inactive X (Xi) erosion. This progressive loss of key repressive features follows the loss of XIST expression, the long non-coding RNA driving X inactivation, and causes reactivation of silenced genes across the eroding X (Xe). To date, the sporadic and progressive nature of erosion has obscured its scale, dynamics, and key transition events. To address this problem, we perform an integrated analysis of DNA methylation (DNAme), chromatin accessibility, and gene expression across hundreds of hPSC samples. Differential DNAme orders female hPSCs across a trajectory from initiation to terminal Xi erosion. Our results identify a cis-regulatory element crucial for XIST expression, trace contiguously growing reactivated domains to a few euchromatic origins, and indicate that the late-stage Xe impairs DNAme genome-wide. Surprisingly, from this altered regulatory landscape emerge select features of naive pluripotency, suggesting that its link to X dosage may be partially conserved in human embryonic development. Reactivation of the silenced X in human female iPSC/ESCs compromises their utility. Bansal et al. perform an integrated genomics analysis to reveal a prevalent X erosion trajectory that they validate in long-term culture. Starting with XIST loss, this trajectory indicates that reactivation may spread contiguously from escapees to silenced genes.
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Affiliation(s)
- Prakhar Bansal
- Graduate Program in Genetics and Developmental Biology, UCONN Health, University of Connecticut, Farmington, CT, USA; Department of Genetics and Genome Sciences, UCONN Health, University of Connecticut, Farmington, CT, USA
| | - Darcy T Ahern
- Graduate Program in Genetics and Developmental Biology, UCONN Health, University of Connecticut, Farmington, CT, USA; Department of Genetics and Genome Sciences, UCONN Health, University of Connecticut, Farmington, CT, USA
| | - Yuvabharath Kondaveeti
- Department of Genetics and Genome Sciences, UCONN Health, University of Connecticut, Farmington, CT, USA
| | - Catherine W Qiu
- Department of Genetics and Genome Sciences, UCONN Health, University of Connecticut, Farmington, CT, USA
| | - Stefan F Pinter
- Graduate Program in Genetics and Developmental Biology, UCONN Health, University of Connecticut, Farmington, CT, USA; Department of Genetics and Genome Sciences, UCONN Health, University of Connecticut, Farmington, CT, USA; Institute for Systems Genomics, University of Connecticut, Farmington, CT, USA.
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41
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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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42
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Ohhata T, Yamazawa K, Miura-Kamio A, Takahashi S, Sakai S, Tamura Y, Uchida C, Kitagawa K, Niida H, Hiratani I, Kobayashi H, Kimura H, Wutz A, Kitagawa M. Dynamics of transcription-mediated conversion from euchromatin to facultative heterochromatin at the Xist promoter by Tsix. Cell Rep 2021; 34:108912. [PMID: 33789104 DOI: 10.1016/j.celrep.2021.108912] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Revised: 10/08/2020] [Accepted: 03/05/2021] [Indexed: 02/07/2023] Open
Abstract
The fine-scale dynamics from euchromatin (EC) to facultative heterochromatin (fHC) has remained largely unclear. Here, we focus on Xist and its silencing initiator Tsix as a paradigm of transcription-mediated conversion from EC to fHC. In mouse epiblast stem cells, induction of Tsix recapitulates the conversion at the Xist promoter. Investigating the dynamics reveals that the conversion proceeds in a stepwise manner. Initially, a transient opened chromatin structure is observed. In the second step, gene silencing is initiated and dependent on Tsix, which is reversible and accompanied by simultaneous changes in multiple histone modifications. At the last step, maintenance of silencing becomes independent of Tsix and irreversible, which correlates with occupation of the -1 position of the transcription start site by a nucleosome and initiation of DNA methylation introduction. This study highlights the hierarchy of multiple chromatin events upon stepwise gene silencing establishment.
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Affiliation(s)
- Tatsuya Ohhata
- Department of Molecular Biology, Hamamatsu University School of Medicine, Hamamatsu 431-3192, Japan.
| | - Kazuki Yamazawa
- Medical Genetics Center, National Hospital Organization Tokyo Medical Center, Tokyo 152-8902, Japan
| | - Asuka Miura-Kamio
- NODAI Genome Research Center, Tokyo University of Agriculture, Tokyo 156-8502, Japan
| | - Saori Takahashi
- Laboratory for Developmental Epigenetics, RIKEN Center for Biosystems Dynamics Research (BDR), Kobe 650-0047, Japan
| | - Satoshi Sakai
- Department of Molecular Biology, Hamamatsu University School of Medicine, Hamamatsu 431-3192, Japan
| | - Yuka Tamura
- Department of Molecular Biology, Hamamatsu University School of Medicine, Hamamatsu 431-3192, Japan
| | - Chiharu Uchida
- Advanced Research Facilities & Services, Preeminent Medical Photonics Education & Research Center, Hamamatsu University School of Medicine, Hamamatsu 431-3192, Japan
| | - Kyoko Kitagawa
- Department of Molecular Biology, Hamamatsu University School of Medicine, Hamamatsu 431-3192, Japan
| | - Hiroyuki Niida
- Department of Molecular Biology, Hamamatsu University School of Medicine, Hamamatsu 431-3192, Japan
| | - Ichiro Hiratani
- Laboratory for Developmental Epigenetics, RIKEN Center for Biosystems Dynamics Research (BDR), Kobe 650-0047, Japan
| | - Hisato Kobayashi
- NODAI Genome Research Center, Tokyo University of Agriculture, Tokyo 156-8502, Japan
| | - Hiroshi Kimura
- Cell Biology Center, Institute of Innovative Research, Tokyo Institute of Technology, Yokohama 226-8503, Japan
| | - Anton Wutz
- Institute of Molecular Health Sciences, Swiss Federal Institute of Technology, ETH Hönggerberg, Otto-Stern-Weg 7, 8093 Zurich, Switzerland
| | - Masatoshi Kitagawa
- Department of Molecular Biology, Hamamatsu University School of Medicine, Hamamatsu 431-3192, Japan.
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43
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Moscatelli M, Rougeulle C. [Latest insights on X-chromosome inactivation: When general principles should be revisited]. Med Sci (Paris) 2021; 37:152-158. [PMID: 33591258 DOI: 10.1051/medsci/2020278] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The inactivation of one of the two X chromosomes of female mammals is a vital process and a paradigm for epigenetic regulations. X-inactivation is triggered, early during embryo development, by the accumulation of a peculiar noncoding RNA, XIST, which interacts with a plethora of molecular complexes and ultimately protects the coated chromosome from the expression machinery. Once installed, the inactive state is locked by multiple layers of chromatin modifications, ensuring its stable perpetuation across cell divisions. However, recent discoveries made in various model organisms urge us to revisit some of the general principles of the X-inactivation process.
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Affiliation(s)
- Madeleine Moscatelli
- Université de Paris, Épigénétique et Destin Cellulaire, CNRS, F-75006 Paris, France
| | - Claire Rougeulle
- Université de Paris, Épigénétique et Destin Cellulaire, CNRS, F-75006 Paris, France
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44
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Ramírez-Colmenero A, Oktaba K, Fernandez-Valverde SL. Evolution of Genome-Organizing Long Non-coding RNAs in Metazoans. Front Genet 2020; 11:589697. [PMID: 33329735 PMCID: PMC7734150 DOI: 10.3389/fgene.2020.589697] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Accepted: 11/09/2020] [Indexed: 12/28/2022] Open
Abstract
Long non-coding RNAs (lncRNAs) have important regulatory functions across eukarya. It is now clear that many of these functions are related to gene expression regulation through their capacity to recruit epigenetic modifiers and establish chromatin interactions. Several lncRNAs have been recently shown to participate in modulating chromatin within the spatial organization of the genome in the three-dimensional space of the nucleus. The identification of lncRNA candidates is challenging, as it is their functional characterization. Conservation signatures of lncRNAs are different from those of protein-coding genes, making identifying lncRNAs under selection a difficult task, and the homology between lncRNAs may not be readily apparent. Here, we review the evidence for these higher-order genome organization functions of lncRNAs in animals and the evolutionary signatures they display.
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Affiliation(s)
- América Ramírez-Colmenero
- Unidad de Genómica Avanzada (Langebio), Centro de Investigación y de Estudios Avanzados del IPN, Irapuato, México
| | - Katarzyna Oktaba
- Unidad Irapuato, Centro de Investigación y de Estudios Avanzados del IPN, Irapuato, México
| | - Selene L Fernandez-Valverde
- Unidad de Genómica Avanzada (Langebio), Centro de Investigación y de Estudios Avanzados del IPN, Irapuato, México
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45
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Panda A, Zylicz JJ, Pasque V. New Insights into X-Chromosome Reactivation during Reprogramming to Pluripotency. Cells 2020; 9:E2706. [PMID: 33348832 PMCID: PMC7766869 DOI: 10.3390/cells9122706] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2020] [Revised: 12/08/2020] [Accepted: 12/10/2020] [Indexed: 02/06/2023] Open
Abstract
Dosage compensation between the sexes results in one X chromosome being inactivated during female mammalian development. Chromosome-wide transcriptional silencing from the inactive X chromosome (Xi) in mammalian cells is erased in a process termed X-chromosome reactivation (XCR), which has emerged as a paradigm for studying the reversal of chromatin silencing. XCR is linked with germline development and induction of naive pluripotency in the epiblast, and also takes place upon reprogramming somatic cells to induced pluripotency. XCR depends on silencing of the long non-coding RNA (lncRNA) X inactive specific transcript (Xist) and is linked with the erasure of chromatin silencing. Over the past years, the advent of transcriptomics and epigenomics has provided new insights into the transcriptional and chromatin dynamics with which XCR takes place. However, multiple questions remain unanswered about how chromatin and transcription related processes enable XCR. Here, we review recent work on establishing the transcriptional and chromatin kinetics of XCR, as well as discuss a model by which transcription factors mediate XCR not only via Xist repression, but also by direct targeting of X-linked genes.
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Affiliation(s)
- Amitesh Panda
- Laboratory of Cellular Reprogramming and Epigenetic Regulation, Department of Development and Regeneration, Leuven Stem Cell Institute, KU Leuven-University of Leuven, 3000 Leuven, Belgium;
| | - Jan J. Zylicz
- The Novo Nordisk Foundation Center for Stem Cell Biology, University of Copenhagen, 2200 Copenhagen, Denmark;
| | - Vincent Pasque
- Laboratory of Cellular Reprogramming and Epigenetic Regulation, Department of Development and Regeneration, Leuven Stem Cell Institute, KU Leuven-University of Leuven, 3000 Leuven, Belgium;
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46
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Hagen SH, Henseling F, Hennesen J, Savel H, Delahaye S, Richert L, Ziegler SM, Altfeld M. Heterogeneous Escape from X Chromosome Inactivation Results in Sex Differences in Type I IFN Responses at the Single Human pDC Level. Cell Rep 2020; 33:108485. [PMID: 33296655 PMCID: PMC7833293 DOI: 10.1016/j.celrep.2020.108485] [Citation(s) in RCA: 68] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Revised: 09/11/2020] [Accepted: 11/12/2020] [Indexed: 12/28/2022] Open
Abstract
Immune responses differ between women and men, and type I interferon (IFN) responses following Toll-like receptor 7 (TLR7) stimulation are higher in women. The precise mechanisms driving these sex differences in immunity are unknown. To investigate possible genetic factors, we quantify escape from X chromosome inactivation (XCI) for TLR7 and four other genes (RPS6KA3, CYBB, BTK, and IL13RA1) at the single plasmacytoid dendritic cell (pDC) level. We observe escape from XCI for all investigated genes, leading to biallelic expression patterns. pDCs with biallelic gene expression have significantly higher mRNA levels of the respective genes. Unstimulated pDCs with biallelic TLR7 expression exhibit significantly higher IFNα/β mRNA levels, and IFNα exposure results in significantly increased IFNα/β protein production by pDCs. These results identify unanticipated heterogeneity in escape from XCI of several genes in pDCs and highlight the important contribution of X chromosome factors to sex differences in type I IFN responses, which might explain observed sex differences in human diseases.
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Affiliation(s)
- Sven Hendrik Hagen
- Research Department Virus Immunology, Heinrich Pette Institute, Leibniz Institute for Experimental Virology, Martinistrasse 52, Hamburg 20251, Germany
| | - Florian Henseling
- Research Department Virus Immunology, Heinrich Pette Institute, Leibniz Institute for Experimental Virology, Martinistrasse 52, Hamburg 20251, Germany
| | - Jana Hennesen
- Technology Platform Flow Cytometry/FACS, Heinrich Pette Institute, Leibniz Institute for Experimental Virology, Martinistrasse 52, Hamburg 20251, Germany
| | - Hélène Savel
- University of Bordeaux, Inserm, Bordeaux Population Health Research Center, UMR1219 and Inria, team SISTM, Bordeaux, France
| | - Solenne Delahaye
- University of Bordeaux, Inserm, Bordeaux Population Health Research Center, UMR1219 and Inria, team SISTM, Bordeaux, France
| | - Laura Richert
- University of Bordeaux, Inserm, Bordeaux Population Health Research Center, UMR1219 and Inria, team SISTM, Bordeaux, France
| | - Susanne Maria Ziegler
- Research Department Virus Immunology, Heinrich Pette Institute, Leibniz Institute for Experimental Virology, Martinistrasse 52, Hamburg 20251, Germany
| | - Marcus Altfeld
- Research Department Virus Immunology, Heinrich Pette Institute, Leibniz Institute for Experimental Virology, Martinistrasse 52, Hamburg 20251, Germany.
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47
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A protein assembly mediates Xist localization and gene silencing. Nature 2020; 587:145-151. [PMID: 32908311 PMCID: PMC7644664 DOI: 10.1038/s41586-020-2703-0] [Citation(s) in RCA: 103] [Impact Index Per Article: 25.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2019] [Accepted: 06/17/2020] [Indexed: 12/22/2022]
Abstract
Nuclear compartments play diverse roles in regulating gene expression, yet the molecular forces and components driving compartment formation remain largely unclear1. The long non-coding RNA Xist establishes an intra-chromosomal compartment by localizing at a high concentration in a territory spatially close to its transcription locus2 and binding diverse proteins3–5 to achieve X-chromosome inactivation (XCI)6,7. The XCI-process therefore serves as paradigm for understanding how RNA-mediated recruitment of diffusible proteins induces a functional compartment. Interestingly, the properties of the inactive X (Xi)-compartment change over time because upon initial Xist spreading and transcriptional shutoff a state is reached where gene silencing remains stable even if Xist is turned off8. Here, we show that the Xist RNA-binding-proteins (RBPs) PTBP19, MATR310, TDP4311, and CELF112 assemble on the multivalent E-repeat-element of Xist7 and, via self-aggregation and heterotypic protein-protein interactions, form a condensate1 in the Xi. This condensate is required for gene silencing and anchoring of Xist to the Xi-territory and can be sustained in the absence of Xist. Notably, these E-repeat-binding RBPs become essential coincident with transition to the Xist-independent XCI-phase8, indicating that the condensate seeded by the E-repeat underlies the developmental switch from Xist-dependence to Xist-independence. Taken together, our data reveal that Xist forms the Xi-compartment by seeding a heteromeric condensate consisting of ubiquitous RBPs and uncover an unanticipated mechanism for heritable gene silencing.
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48
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Wang D, Tang L, Wu Y, Fan C, Zhang S, Xiang B, Zhou M, Li X, Li Y, Li G, Xiong W, Zeng Z, Guo C. Abnormal X chromosome inactivation and tumor development. Cell Mol Life Sci 2020; 77:2949-2958. [PMID: 32040694 PMCID: PMC11104905 DOI: 10.1007/s00018-020-03469-z] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2019] [Revised: 01/17/2020] [Accepted: 01/21/2020] [Indexed: 12/13/2022]
Abstract
During embryonic development, one of the two X chromosomes of a mammalian female cell is randomly inactivated by the X chromosome inactivation mechanism, which is mainly dependent on the regulation of the non-coding RNA X-inactive specific transcript at the X chromosome inactivation center. There are three proteins that are essential for X-inactive specific transcript to function properly: scaffold attachment factor-A, lamin B receptor, and SMRT- and HDAC-associated repressor protein. In addition, the absence of X-inactive specific transcript expression promotes tumor development. During the process of chromosome inactivation, some tumor suppressor genes escape inactivation of the X chromosome and thereby continue to play a role in tumor suppression. A well-functioning tumor suppressor gene on the idle X chromosome in women is one of the reasons they have a lower propensity to develop cancer than men, women thereby benefit from this enhanced tumor suppression. This review will explore the mechanism of X chromosome inactivation, discuss the relationship between X chromosome inactivation and tumorigenesis, and consider the consequent sex differences in cancer.
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Affiliation(s)
- Dan Wang
- Department of Stomatology, NHC Key Laboratory of Carcinogenesis, Xiangya Hospital, Central South University, Changsha, Hunan, China
- Key Laboratory of Carcinogenesis and Cancer Invasion of the Chinese Ministry of Education, Cancer Research Institute, Central South University, Changsha, Hunan, China
- Hunan Key Laboratory of Nonresolving Inflammation and Cancer, Disease Genome Research Center, The Third Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Le Tang
- Key Laboratory of Carcinogenesis and Cancer Invasion of the Chinese Ministry of Education, Cancer Research Institute, Central South University, Changsha, Hunan, China
| | - Yingfen Wu
- Key Laboratory of Carcinogenesis and Cancer Invasion of the Chinese Ministry of Education, Cancer Research Institute, Central South University, Changsha, Hunan, China
| | - Chunmei Fan
- Key Laboratory of Carcinogenesis and Cancer Invasion of the Chinese Ministry of Education, Cancer Research Institute, Central South University, Changsha, Hunan, China
| | - Shanshan Zhang
- Department of Stomatology, NHC Key Laboratory of Carcinogenesis, Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Bo Xiang
- Key Laboratory of Carcinogenesis and Cancer Invasion of the Chinese Ministry of Education, Cancer Research Institute, Central South University, Changsha, Hunan, China
| | - Ming Zhou
- Key Laboratory of Carcinogenesis and Cancer Invasion of the Chinese Ministry of Education, Cancer Research Institute, Central South University, Changsha, Hunan, China
| | - Xiaoling Li
- Key Laboratory of Carcinogenesis and Cancer Invasion of the Chinese Ministry of Education, Cancer Research Institute, Central South University, Changsha, Hunan, China
| | - Yong Li
- Department of Medicine, Dan L Duncan Comprehensive Cancer Center, Baylor College of Medicine, Houston, Texas, USA
| | - Guiyuan Li
- Key Laboratory of Carcinogenesis and Cancer Invasion of the Chinese Ministry of Education, Cancer Research Institute, Central South University, Changsha, Hunan, China
| | - Wei Xiong
- Key Laboratory of Carcinogenesis and Cancer Invasion of the Chinese Ministry of Education, Cancer Research Institute, Central South University, Changsha, Hunan, China
| | - Zhaoyang Zeng
- Key Laboratory of Carcinogenesis and Cancer Invasion of the Chinese Ministry of Education, Cancer Research Institute, Central South University, Changsha, Hunan, China
| | - Can Guo
- Department of Stomatology, NHC Key Laboratory of Carcinogenesis, Xiangya Hospital, Central South University, Changsha, Hunan, China.
- Key Laboratory of Carcinogenesis and Cancer Invasion of the Chinese Ministry of Education, Cancer Research Institute, Central South University, Changsha, Hunan, China.
- Hunan Key Laboratory of Nonresolving Inflammation and Cancer, Disease Genome Research Center, The Third Xiangya Hospital, Central South University, Changsha, Hunan, China.
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49
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Żylicz JJ, Heard E. Molecular Mechanisms of Facultative Heterochromatin Formation: An X-Chromosome Perspective. Annu Rev Biochem 2020; 89:255-282. [PMID: 32259458 DOI: 10.1146/annurev-biochem-062917-012655] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Facultative heterochromatin (fHC) concerns the developmentally regulated heterochromatinization of different regions of the genome and, in the case of the mammalian X chromosome and imprinted loci, of only one allele of a homologous pair. The formation of fHC participates in the timely repression of genes, by resisting strong trans activators. In this review, we discuss the molecular mechanisms underlying the establishment and maintenance of fHC in mammals using a mouse model. We focus on X-chromosome inactivation (XCI) as a paradigm for fHC but also relate it to genomic imprinting and homeobox (Hox) gene cluster repression. A vital role for noncoding transcription and/or transcripts emerges as the general principle of triggering XCI and canonical imprinting. However, other types of fHC are established through an unknown mechanism, independent of noncoding transcription (Hox clusters and noncanonical imprinting). We also extensively discuss polycomb-group repressive complexes (PRCs), which frequently play a vital role in fHC maintenance.
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Affiliation(s)
- Jan J Żylicz
- Mammalian Developmental Epigenetics Group, Institut Curie, CNRS UMR 3215, INSERM U934, PSL University, 75248 Paris Cedex 05, France.,Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3EL, United Kingdom
| | - Edith Heard
- Directors' Research, EMBL Heidelberg, 69117 Heidelberg, Germany;
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50
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Xist Repeats A and B Account for Two Distinct Phases of X Inactivation Establishment. Dev Cell 2020; 54:21-32.e5. [PMID: 32531209 DOI: 10.1016/j.devcel.2020.05.021] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Revised: 02/16/2020] [Accepted: 05/14/2020] [Indexed: 11/20/2022]
Abstract
X chromosome inactivation (XCI) is a global silencing mechanism by which XX and XY mammals equalize X-linked gene dosages. XCI begins with an establishment phase during which Xist RNA spreads and induces de novo heterochromatinization across a female X chromosome and is followed by a maintenance phase when multiple epigenetic pathways lock down the inactive X (Xi) state. Involvement of Polycomb repressive complexes 1 and 2 in XCI has been intensively studied but with conflicting conclusions regarding their recruitment and role in Xi silencing. Here, we reveal that establishment of XCI has two phases and reconcile the roles that Xist repeats A and B play in gene silencing and Polycomb recruitment. Repeat A initiates both processes, whereas repeat B bolsters or stabilizes them thereafter. Once established, XCI no longer requires repeat A during maintenance. These findings integrate disparate studies and present a unified view of Xist's role in Polycomb-mediated silencing.
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