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Gupta K, Czerminski JT, Lawrence JB. Trisomy silencing by XIST: translational prospects and challenges. Hum Genet 2024; 143:843-855. [PMID: 38459355 PMCID: PMC11294271 DOI: 10.1007/s00439-024-02651-8] [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] [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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2
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Naseer QA, Malik A, Zhang F, Chen S. Exploring the enigma: history, present, and future of long non-coding RNAs in cancer. Discov Oncol 2024; 15:214. [PMID: 38847897 PMCID: PMC11161455 DOI: 10.1007/s12672-024-01077-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/23/2024] [Accepted: 06/03/2024] [Indexed: 06/10/2024] Open
Abstract
Long noncoding RNAs (lncRNAs), which are more than 200 nucleotides in length and do not encode proteins, play crucial roles in governing gene expression at both the transcriptional and posttranscriptional levels. These molecules demonstrate specific expression patterns in various tissues and developmental stages, suggesting their involvement in numerous developmental processes and diseases, notably cancer. Despite their widespread acknowledgment and the growing enthusiasm surrounding their potential as diagnostic and prognostic biomarkers, the precise mechanisms through which lncRNAs function remain inadequately understood. A few lncRNAs have been studied in depth, providing valuable insights into their biological activities and suggesting emerging functional themes and mechanistic models. However, the extent to which the mammalian genome is transcribed into functional noncoding transcripts is still a matter of debate. This review synthesizes our current understanding of lncRNA biogenesis, their genomic contexts, and their multifaceted roles in tumorigenesis, highlighting their potential in cancer-targeted therapy. By exploring historical perspectives alongside recent breakthroughs, we aim to illuminate the diverse roles of lncRNA and reflect on the broader implications of their study for understanding genome evolution and function, as well as for advancing clinical applications.
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Affiliation(s)
- Qais Ahmad Naseer
- Department of Laboratory Medicine, School of Medicine, Jiangsu University, 301 Xuefu Road, Zhenjiang, 212013, China
| | - Abdul Malik
- Department of Laboratory Medicine, School of Medicine, Jiangsu University, 301 Xuefu Road, Zhenjiang, 212013, China
| | - Fengyuan Zhang
- Department of Laboratory Medicine, School of Medicine, Jiangsu University, 301 Xuefu Road, Zhenjiang, 212013, China
| | - Shengxia Chen
- Department of Laboratory Medicine, School of Medicine, Jiangsu University, 301 Xuefu Road, Zhenjiang, 212013, China.
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3
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Tomikawa J. Potential roles of inter-chromosomal interactions in cell fate determination. Front Cell Dev Biol 2024; 12:1397807. [PMID: 38774644 PMCID: PMC11106443 DOI: 10.3389/fcell.2024.1397807] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2024] [Accepted: 04/23/2024] [Indexed: 05/24/2024] Open
Abstract
Mammalian genomic DNA is packed in a small nucleus, and its folding and organization in the nucleus are critical for gene regulation and cell fate determination. In interphase, chromosomes are compartmentalized into certain nuclear spaces and territories that are considered incompatible with each other. The regulation of gene expression is influenced by the epigenetic characteristics of topologically associated domains and A/B compartments within chromosomes (intrachromosomal). Previously, interactions among chromosomes detected via chromosome conformation capture-based methods were considered noise or artificial errors. However, recent studies based on newly developed ligation-independent methods have shown that inter-chromosomal interactions play important roles in gene regulation. This review summarizes the recent understanding of spatial genomic organization in mammalian interphase nuclei and discusses the potential mechanisms that determine cell identity. In addition, this review highlights the potential role of inter-chromosomal interactions in early mouse development.
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Affiliation(s)
- Junko Tomikawa
- Department of Maternal-Fetal Biology, National Research Institute for Child Health and Development, Tokyo, Japan
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4
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Schwämmle T, Schulz EG. Regulatory principles and mechanisms governing the onset of random X-chromosome inactivation. Curr Opin Genet Dev 2023; 81:102063. [PMID: 37356341 PMCID: PMC10465972 DOI: 10.1016/j.gde.2023.102063] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Revised: 05/23/2023] [Accepted: 05/24/2023] [Indexed: 06/27/2023]
Abstract
X-chromosome inactivation (XCI) has evolved in mammals to compensate for the difference in X-chromosomal dosage between the sexes. In placental mammals, XCI is initiated during early embryonic development through upregulation of the long noncoding RNA Xist from one randomly chosen X chromosome in each female cell. The Xist locus must thus integrate both X-linked and developmental trans-regulatory factors in a dosage-dependent manner. Furthermore, the two alleles must coordinate to ensure inactivation of exactly one X chromosome per cell. In this review, we summarize the regulatory principles that govern the onset of XCI. We go on to provide an overview over the factors that have been implicated in Xist regulation and discuss recent advances in our understanding of how Xist's cis-regulatory landscape integrates information in a precise fashion.
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Affiliation(s)
- Till Schwämmle
- Otto Warburg Laboratories, Max Planck Institute for Molecular Genetics, Berlin, Germany. https://twitter.com/@TSchwammle
| | - Edda G Schulz
- Otto Warburg Laboratories, Max Planck Institute for Molecular Genetics, Berlin, Germany.
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5
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Nickbarg EB, Spencer KB, Mortison JD, Lee JT. Targeting RNA with small molecules: lessons learned from Xist RNA. RNA (NEW YORK, N.Y.) 2023; 29:463-472. [PMID: 36725318 PMCID: PMC10019374 DOI: 10.1261/rna.079523.122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Although more than 98% of the human genome is noncoding, nearly all drugs on the market target one of about 700 disease-related proteins. However, an increasing number of diseases are now being attributed to noncoding RNA and the ability to target them would vastly expand the chemical space for drug development. We recently devised a screening strategy based upon affinity-selection mass spectrometry and succeeded in identifying bioactive compounds for the noncoding RNA prototype, Xist. One such compound, termed X1, has drug-like properties and binds specifically to the RepA motif of Xist in vitro and in vivo. Small-angle X-ray scattering analysis reveals that X1 changes the conformation of RepA in solution, thereby explaining the displacement of cognate interacting protein factors (PRC2 and SPEN) and inhibition of X-chromosome inactivation. In this Perspective, we discuss lessons learned from these proof-of-concept experiments and suggest that RNA can be systematically targeted by drug-like compounds to disrupt RNA structure and function.
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Affiliation(s)
| | | | | | - Jeannie T Lee
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts 02114, USA
- Department of Genetics, The Blavatnik Institute, Harvard Medical School, Boston, Massachusetts 02115, USA
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6
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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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7
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Yamamoto R, Sato G, Amai T, Ueda M, Kuroda K. Development of Artificial System to Induce Chromatin Loosening in Saccharomyces cerevisiae. Biomolecules 2022; 12:1138. [PMID: 36009033 PMCID: PMC9406041 DOI: 10.3390/biom12081138] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Accepted: 08/16/2022] [Indexed: 12/05/2022] Open
Abstract
In eukaryotic cells, loosening of chromatin causes changes in transcription and DNA replication. The artificial conversion of tightly packed chromatin (heterochromatin) to loosely packed chromatin (euchromatin) enables gene expression and regulates cell differentiation. Although some chemicals convert chromatin structures through histone modifications, they lack sequence specificity. This study attempted to establish a novel technology for inducing chromatin loosening in target regions of Saccharomyces cerevisiae. We focused on histone acetylation, which is one of the mechanisms of euchromatin induction. The sequence-recognizing ability of the dead Cas9 (dCas9) and guide RNA (gRNA) complex was used to promote histone acetylation at a targeted genomic locus. We constructed a plasmid to produce a fusion protein consisting of dCas9 and histone acetyltransferase Gcn5 and a plasmid to express gRNA recognizing the upstream region of heterochromatic URA3. Confocal microscopy revealed that the fusion proteins were localized in the nucleus. The yeast strain producing the fusion protein and gRNA grew well in the uracil-deficient medium, while the strain harboring empty plasmids or the strain containing the mutations that cause loss of nucleosomal histone acetylation activity of Gcn5 did not. This suggests that the heterochromatin was loosened as much as euchromatin through nucleosomal histone acetylation. The amount of euchromatic DNA at the target locus increased, indicating that chromatin loosening was induced by our system. Nucleosomal histone acetylation in heterochromatic loci by our developed system is a promising method for inducing euchromatic state in a target locus.
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Affiliation(s)
| | | | | | | | - Kouichi Kuroda
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan
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8
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Ichihara S, Nagao K, Sakaguchi T, Obuse C, Sado T. SmcHD1 underlies the formation of H3K9me3 blocks on the inactive X chromosome in mice. Development 2022; 149:dev200864. [PMID: 38771307 DOI: 10.1242/dev.200864] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Accepted: 06/30/2022] [Indexed: 12/12/2022]
Abstract
Stable silencing of the inactive X chromosome (Xi) in female mammals is crucial for the development of embryos and their postnatal health. SmcHD1 is essential for stable silencing of the Xi, and its functional deficiency results in derepression of many X-inactivated genes. Although SmcHD1 has been suggested to play an important role in the formation of higher-order chromatin structure of the Xi, the underlying mechanism is largely unknown. Here, we explore the epigenetic state of the Xi in SmcHD1-deficient epiblast stem cells and mouse embryonic fibroblasts in comparison with their wild-type counterparts. The results suggest that SmcHD1 underlies the formation of H3K9me3-enriched blocks on the Xi, which, although the importance of H3K9me3 has been largely overlooked in mice, play a crucial role in the establishment of the stably silenced state. We propose that the H3K9me3 blocks formed on the Xi facilitate robust heterochromatin formation in combination with H3K27me3, and that the substantial loss of H3K9me3 caused by SmcHD1 deficiency leads to aberrant distribution of H3K27me3 on the Xi and derepression of X-inactivated genes.
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Affiliation(s)
- Saya Ichihara
- Department of Advanced Bioscience, Graduate School of Agriculture, Kindai University, Nara 631-8505, Japan
| | - Koji Nagao
- Department of Biological Science, Graduate School of Science, Osaka University, Toyonaka 560-0043, Japan
| | - Takehisa Sakaguchi
- Medical Institute of Bioregulation, Kyushu University, Fukuoka 812-8582, Japan
| | - Chikashi Obuse
- Department of Biological Science, Graduate School of Science, Osaka University, Toyonaka 560-0043, Japan
| | - Takashi Sado
- Department of Advanced Bioscience, Graduate School of Agriculture, Kindai University, Nara 631-8505, Japan
- Agricultural Technology and Innovation Research Institute, Kindai University, Nara 631-8505, Japan
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9
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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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10
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Gjaltema RAF, Schwämmle T, Kautz P, Robson M, Schöpflin R, Ravid Lustig L, Brandenburg L, Dunkel I, Vechiatto C, Ntini E, Mutzel V, Schmiedel V, Marsico A, Mundlos S, Schulz EG. Distal and proximal cis-regulatory elements sense X chromosome dosage and developmental state at the Xist locus. Mol Cell 2022; 82:190-208.e17. [PMID: 34932975 DOI: 10.1016/j.molcel.2021.11.023] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 11/22/2021] [Accepted: 11/23/2021] [Indexed: 12/15/2022]
Abstract
Developmental genes such as Xist, which initiates X chromosome inactivation, are controlled by complex cis-regulatory landscapes, which decode multiple signals to establish specific spatiotemporal expression patterns. Xist integrates information on X chromosome dosage and developmental stage to trigger X inactivation in the epiblast specifically in female embryos. Through a pooled CRISPR screen in differentiating mouse embryonic stem cells, we identify functional enhancer elements of Xist at the onset of random X inactivation. Chromatin profiling reveals that X-dosage controls the promoter-proximal region, while differentiation cues activate several distal enhancers. The strongest distal element lies in an enhancer cluster associated with a previously unannotated Xist-enhancing regulatory transcript, which we named Xert. Developmental cues and X-dosage are thus decoded by distinct regulatory regions, which cooperate to ensure female-specific Xist upregulation at the correct developmental time. With this study, we start to disentangle how multiple, functionally distinct regulatory elements interact to generate complex expression patterns in mammals.
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Affiliation(s)
- Rutger A F Gjaltema
- Otto Warburg Laboratories, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany
| | - Till Schwämmle
- Otto Warburg Laboratories, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany
| | - Pauline Kautz
- Otto Warburg Laboratories, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany
| | - Michael Robson
- Development and Disease Group, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany; Medical Research Council Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh EH4 2XU, Edinburgh, UK
| | - Robert Schöpflin
- Development and Disease Group, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany; Institute for Medical and Human Genetics, Charité-Universitätsmedizin Berlin, 13353 Berlin, Germany; Department of Computational Molecular Biology, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany
| | - Liat Ravid Lustig
- Otto Warburg Laboratories, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany
| | - Lennart Brandenburg
- Otto Warburg Laboratories, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany
| | - Ilona Dunkel
- Otto Warburg Laboratories, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany
| | - Carolina Vechiatto
- Otto Warburg Laboratories, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany
| | - Evgenia Ntini
- Otto Warburg Laboratories, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany
| | - Verena Mutzel
- Otto Warburg Laboratories, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany
| | - Vera Schmiedel
- Otto Warburg Laboratories, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany
| | - Annalisa Marsico
- Computational Health Center, Helmholtz Center München, 85764 Neuherberg, Germany
| | - Stefan Mundlos
- Development and Disease Group, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany; Institute for Medical and Human Genetics, Charité-Universitätsmedizin Berlin, 13353 Berlin, Germany
| | - Edda G Schulz
- Otto Warburg Laboratories, Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany.
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11
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Raposo AC, Casanova M, Gendrel AV, da Rocha ST. The tandem repeat modules of Xist lncRNA: a swiss army knife for the control of X-chromosome inactivation. Biochem Soc Trans 2021; 49:2549-2560. [PMID: 34882219 PMCID: PMC8786293 DOI: 10.1042/bst20210253] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Revised: 11/19/2021] [Accepted: 11/23/2021] [Indexed: 12/16/2022]
Abstract
X-inactive-specific transcript (Xist) is a long non-coding RNA (lncRNA) essential for X-chromosome inactivation (XCI) in female placental mammals. Thirty years after its discovery, it is still puzzling how this lncRNA triggers major structural and transcriptional changes leading to the stable silencing of an entire chromosome. Recently, a series of studies in mouse cells have uncovered domains of functional specialization within Xist mapping to conserved tandem repeat regions, known as Repeats A-to-F. These functional domains interact with various RNA binding proteins (RBPs) and fold into distinct RNA structures to execute specific tasks in a synergistic and coordinated manner during the inactivation process. This modular organization of Xist is mostly conserved in humans, but recent data point towards differences regarding functional specialization of the tandem repeats between the two species. In this review, we summarize the recent progress on understanding the role of Xist repetitive blocks and their involvement in the molecular mechanisms underlying XCI. We also discuss these findings in the light of the similarities and differences between mouse and human Xist.
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Affiliation(s)
- Ana Cláudia Raposo
- Departamento de Bioengenharia e Instituto de Bioengenharia e Biociências, Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal
- Associate Laboratory i4HB - Institute for Health and Bioeconomy, Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
| | - Miguel Casanova
- Departamento de Bioengenharia e Instituto de Bioengenharia e Biociências, Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal
- Associate Laboratory i4HB - Institute for Health and Bioeconomy, Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
| | - Anne-Valerie Gendrel
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
| | - Simão Teixeira da Rocha
- Departamento de Bioengenharia e Instituto de Bioengenharia e Biociências, Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal
- Associate Laboratory i4HB - Institute for Health and Bioeconomy, Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisbon, Portugal
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12
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Robert-Finestra T, Tan BF, Mira-Bontenbal H, Timmers E, Gontan C, Merzouk S, Giaimo BD, Dossin F, van IJcken WFJ, Martens JWM, Borggrefe T, Heard E, Gribnau J. SPEN is required for Xist upregulation during initiation of X chromosome inactivation. Nat Commun 2021; 12:7000. [PMID: 34853312 PMCID: PMC8636516 DOI: 10.1038/s41467-021-27294-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Accepted: 11/08/2021] [Indexed: 01/11/2023] Open
Abstract
At initiation of X chromosome inactivation (XCI), Xist is monoallelically upregulated from the future inactive X (Xi) chromosome, overcoming repression by its antisense transcript Tsix. Xist recruits various chromatin remodelers, amongst them SPEN, which are involved in silencing of X-linked genes in cis and establishment of the Xi. Here, we show that SPEN plays an important role in initiation of XCI. Spen null female mouse embryonic stem cells (ESCs) are defective in Xist upregulation upon differentiation. We find that Xist-mediated SPEN recruitment to the Xi chromosome happens very early in XCI, and that SPEN-mediated silencing of the Tsix promoter is required for Xist upregulation. Accordingly, failed Xist upregulation in Spen-/- ESCs can be rescued by concomitant removal of Tsix. These findings indicate that SPEN is not only required for the establishment of the Xi, but is also crucial in initiation of the XCI process.
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Affiliation(s)
- Teresa Robert-Finestra
- Department of Developmental Biology, Erasmus University Medical Center, Oncode Institute, 3015GD, Rotterdam, The Netherlands
| | - Beatrice F Tan
- Department of Developmental Biology, Erasmus University Medical Center, Oncode Institute, 3015GD, Rotterdam, The Netherlands
| | - Hegias Mira-Bontenbal
- Department of Developmental Biology, Erasmus University Medical Center, Oncode Institute, 3015GD, Rotterdam, The Netherlands
| | - Erika Timmers
- Department of Developmental Biology, Erasmus University Medical Center, Oncode Institute, 3015GD, Rotterdam, The Netherlands
| | - Cristina Gontan
- Department of Developmental Biology, Erasmus University Medical Center, Oncode Institute, 3015GD, Rotterdam, The Netherlands
| | - Sarra Merzouk
- Department of Developmental Biology, Erasmus University Medical Center, Oncode Institute, 3015GD, Rotterdam, The Netherlands
| | | | - François Dossin
- European Molecular Biology Laboratory, Director's Research, 69117, Heidelberg, Germany
| | - Wilfred F J van IJcken
- Center for Biomics, Erasmus University Medical Center, 3015CN, Rotterdam, The Netherlands
| | - John W M Martens
- Department of Medical Oncology, Erasmus MC Cancer Institute and Cancer Genomics Netherlands, Erasmus University Medical Center, 3015CN, Rotterdam, The Netherlands
| | - Tilman Borggrefe
- Institute of Biochemistry, University of Giessen, 35392, Giessen, Germany
| | - Edith Heard
- European Molecular Biology Laboratory, Director's Research, 69117, Heidelberg, Germany
| | - Joost Gribnau
- Department of Developmental Biology, Erasmus University Medical Center, Oncode Institute, 3015GD, Rotterdam, The Netherlands.
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13
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Trotman JB, Braceros KCA, Cherney RE, Murvin MM, Calabrese JM. The control of polycomb repressive complexes by long noncoding RNAs. WILEY INTERDISCIPLINARY REVIEWS. RNA 2021; 12:e1657. [PMID: 33861025 PMCID: PMC8500928 DOI: 10.1002/wrna.1657] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 01/12/2021] [Accepted: 03/19/2021] [Indexed: 02/06/2023]
Abstract
The polycomb repressive complexes 1 and 2 (PRCs; PRC1 and PRC2) are conserved histone-modifying enzymes that often function cooperatively to repress gene expression. The PRCs are regulated by long noncoding RNAs (lncRNAs) in complex ways. On the one hand, specific lncRNAs cause the PRCs to engage with chromatin and repress gene expression over genomic regions that can span megabases. On the other hand, the PRCs bind RNA with seemingly little sequence specificity, and at least in the case of PRC2, direct RNA-binding has the effect of inhibiting the enzyme. Thus, some RNAs appear to promote PRC activity, while others may inhibit it. The reasons behind this apparent dichotomy are unclear. The most potent PRC-activating lncRNAs associate with chromatin and are predominantly unspliced or harbor unusually long exons. Emerging data imply that these lncRNAs promote PRC activity through internal RNA sequence elements that arise and disappear rapidly in evolutionary time. These sequence elements may function by interacting with common subsets of RNA-binding proteins that recruit or stabilize PRCs on chromatin. This article is categorized under: RNA Interactions with Proteins and Other Molecules > Protein-RNA Recognition RNA Interactions with Proteins and Other Molecules > RNA-Protein Complexes RNA Interactions with Proteins and Other Molecules > Protein-RNA Interactions: Functional Implications.
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Affiliation(s)
- Jackson B. Trotman
- Department of Pharmacology and Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Keean C. A. Braceros
- Department of Pharmacology and Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
- Curriculum in Mechanistic, Interdisciplinary Studies of Biological Systems, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Rachel E. Cherney
- Department of Pharmacology and Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
- Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - McKenzie M. Murvin
- Department of Pharmacology and Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
- Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - J. Mauro Calabrese
- Department of Pharmacology and Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
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14
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Micheel J, Safrastyan A, Wollny D. Advances in Non-Coding RNA Sequencing. Noncoding RNA 2021; 7:70. [PMID: 34842804 PMCID: PMC8628893 DOI: 10.3390/ncrna7040070] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Revised: 10/22/2021] [Accepted: 10/26/2021] [Indexed: 12/11/2022] Open
Abstract
Non-coding RNAs (ncRNAs) comprise a set of abundant and functionally diverse RNA molecules. Since the discovery of the first ncRNA in the 1960s, ncRNAs have been shown to be involved in nearly all steps of the central dogma of molecular biology. In recent years, the pace of discovery of novel ncRNAs and their cellular roles has been greatly accelerated by high-throughput sequencing. Advances in sequencing technology, library preparation protocols as well as computational biology helped to greatly expand our knowledge of which ncRNAs exist throughout the kingdoms of life. Moreover, RNA sequencing revealed crucial roles of many ncRNAs in human health and disease. In this review, we discuss the most recent methodological advancements in the rapidly evolving field of high-throughput sequencing and how it has greatly expanded our understanding of ncRNA biology across a large number of different organisms.
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Affiliation(s)
| | | | - Damian Wollny
- RNA Bioinformatics/High Throughput Analysis, Faculty of Mathematics and Computer Science, Friedrich Schiller University, 07743 Jena, Germany; (J.M.); (A.S.)
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15
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ArcRNAs and the formation of nuclear bodies. Mamm Genome 2021; 33:382-401. [PMID: 34085114 DOI: 10.1007/s00335-021-09881-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Accepted: 05/25/2021] [Indexed: 01/13/2023]
Abstract
Long noncoding RNAs (lncRNAs) have long been collectively and passively defined as transcripts that do not encode proteins. However, extensive functional studies performed over the last decade have enabled the classification of lncRNAs into multiple categories according to their functions and/or molecular properties. Architectual RNAs (arcRNAs) are a group of lncRNAs that serve as architectural components of submicron-scale cellular bodies or nonmembranous organelles, which are composed of specific sets of proteins and nucleic acids involved in particular molecular processes. In this review, we focus on arcRNAs that function in the nucleus, which provide a structural basis for the formation of nuclear bodies, nonmembranous organelles in the cell nucleus. We will summarize the current list of arcRNAs and proteins associated with classic and more recently discovered nuclear bodies and discuss general rules that govern the formation of nuclear bodies, emphasizing weak multivalent interactions mediated by innately flexible biomolecules.
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16
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Mutzel V, Schulz EG. Dosage Sensing, Threshold Responses, and Epigenetic Memory: A Systems Biology Perspective on Random X-Chromosome Inactivation. Bioessays 2021; 42:e1900163. [PMID: 32189388 DOI: 10.1002/bies.201900163] [Citation(s) in RCA: 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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17
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Song Z, Lin J, Li Z, Huang C. The nuclear functions of long noncoding RNAs come into focus. Noncoding RNA Res 2021; 6:70-79. [PMID: 33898883 PMCID: PMC8053782 DOI: 10.1016/j.ncrna.2021.03.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Revised: 03/18/2021] [Accepted: 03/22/2021] [Indexed: 12/16/2022] Open
Abstract
Long noncoding RNAs (lncRNAs), defined as untranslated and tightly-regulated transcripts with a length exceeding 200 nt, are common outputs of the eukaryotic genome. It is becoming increasingly apparent that many lncRNAs likely serve as important regulators in a variety of biological processes. In particular, some of them accumulate in the nucleus and function in diverse nuclear events, including chromatin remodeling, transcriptional regulation, RNA processing, DNA damage repair, etc. Here, we unite recent progresses on the functions of nuclear lncRNAs and provide insights into the future research directions of this field.
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Affiliation(s)
- Zhenxing Song
- School of Life Sciences, Chongqing University, Chongqing, 401331, China
- Center of Plant Functional Genomics, Institute of Advanced Interdisciplinary Studies, Chongqing University, Chongqing, 401331, China
| | - Jiamei Lin
- School of Life Sciences, Chongqing University, Chongqing, 401331, China
- Center of Plant Functional Genomics, Institute of Advanced Interdisciplinary Studies, Chongqing University, Chongqing, 401331, China
| | - Zhengguo Li
- School of Life Sciences, Chongqing University, Chongqing, 401331, China
- Center of Plant Functional Genomics, Institute of Advanced Interdisciplinary Studies, Chongqing University, Chongqing, 401331, China
| | - Chuan Huang
- School of Life Sciences, Chongqing University, Chongqing, 401331, China
- Center of Plant Functional Genomics, Institute of Advanced Interdisciplinary Studies, Chongqing University, Chongqing, 401331, China
- Corresponding author. School of Life Sciences, Chongqing University, Chongqing, 401331, China.
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18
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Sas-Nowosielska H, Magalska A. Long Noncoding RNAs-Crucial Players Organizing the Landscape of the Neuronal Nucleus. Int J Mol Sci 2021; 22:ijms22073478. [PMID: 33801737 PMCID: PMC8037058 DOI: 10.3390/ijms22073478] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Revised: 03/22/2021] [Accepted: 03/24/2021] [Indexed: 12/25/2022] Open
Abstract
The ability to regulate chromatin organization is particularly important in neurons, which dynamically respond to external stimuli. Accumulating evidence shows that lncRNAs play important architectural roles in organizing different nuclear domains like inactive chromosome X, splicing speckles, paraspeckles, and Gomafu nuclear bodies. LncRNAs are abundantly expressed in the nervous system where they may play important roles in compartmentalization of the cell nucleus. In this review we will describe the architectural role of lncRNAs in the nuclei of neuronal cells.
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19
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Yu B, Qi Y, Li R, Shi Q, Satpathy AT, Chang HY. B cell-specific XIST complex enforces X-inactivation and restrains atypical B cells. Cell 2021; 184:1790-1803.e17. [PMID: 33735607 DOI: 10.1016/j.cell.2021.02.015] [Citation(s) in RCA: 95] [Impact Index Per Article: 31.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Revised: 12/07/2020] [Accepted: 02/04/2021] [Indexed: 12/16/2022]
Abstract
The long non-coding RNA (lncRNA) XIST establishes X chromosome inactivation (XCI) in female cells in early development and thereafter is thought to be largely dispensable. Here, we show XIST is continually required in adult human B cells to silence a subset of X-linked immune genes such as TLR7. XIST-dependent genes lack promoter DNA methylation and require continual XIST-dependent histone deacetylation. XIST RNA-directed proteomics and CRISPRi screen reveal distinctive somatic cell-type-specific XIST complexes and identify TRIM28 that mediates Pol II pausing at promoters of X-linked genes in B cells. Single-cell transcriptome data of female patients with either systemic lupus erythematosus or COVID-19 infection revealed XIST dysregulation, reflected by escape of XIST-dependent genes, in CD11c+ atypical memory B cells (ABCs). XIST inactivation with TLR7 agonism suffices to promote isotype-switched ABCs. These results indicate cell-type-specific diversification and function for lncRNA-protein complexes and suggest expanded roles for XIST in sex-differences in biology and medicine.
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Affiliation(s)
- Bingfei Yu
- Center for Personal Dynamic Regulomes, Stanford University, Stanford, CA 94305, USA
| | - Yanyan Qi
- Center for Personal Dynamic Regulomes, Stanford University, Stanford, CA 94305, USA
| | - Rui Li
- Center for Personal Dynamic Regulomes, Stanford University, Stanford, CA 94305, USA
| | - Quanming Shi
- 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.
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20
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Dixon-McDougall T, Brown CJ. Independent domains for recruitment of PRC1 and PRC2 by human XIST. PLoS Genet 2021; 17:e1009123. [PMID: 33750950 PMCID: PMC8016261 DOI: 10.1371/journal.pgen.1009123] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 04/01/2021] [Accepted: 03/07/2021] [Indexed: 01/08/2023] Open
Abstract
XIST establishes inactivation across its chromosome of origin, even when expressed from autosomal transgenes. To identify the regions of human XIST essential for recruiting heterochromatic marks we generated a series of overlapping deletions in an autosomal inducible XIST transgene present in 8p of the HT1080 male fibrosarcoma cell line. We examined the ability of each construct to enrich its unified XIST territory with the histone marks established by PRC1 and PRC2 as well as the heterochromatin factors MacroH2A and SMCHD1. Chromatin enrichment of ubH2A by PRC1 required four distinct regions of XIST, and these were completely distinct from the two domains crucial for enrichment of H3K27me3 by PRC2. Both the domains required, as well as the impact of PRC1 and PRC2 inhibitors, suggest that PRC1 is required for SMCHD1 while PRC2 function is necessary for MacroH2A recruitment, although incomplete overlap of regions implicates roles for additional factors. This cooperativity between factors contributes to the requirement for multiple separate domains being required for each feature examined. The independence of the PRC1/PRC2 pathways was observed when XIST was expressed both autosomally or from the X chromosome suggesting that these observations are not purely a result of the context in which XIST operates. Although independent domains were required for the PRC1 and PRC2 pathways overall all regions tested were important for some aspect of XIST functionality, demonstrating both modularity and cooperativity across the XIST lncRNA.
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Affiliation(s)
- Thomas Dixon-McDougall
- Department of Medical Genetics, University of British Columbia, Vancouver, British Columbia, Canada
| | - Carolyn J. Brown
- Department of Medical Genetics, University of British Columbia, Vancouver, British Columbia, Canada
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21
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Yu B, Qi Y, Li R, Shi Q, Satpathy A, Chang HY. B cell-specific XIST complex enforces X-inactivation and restrains atypical B cells. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2021. [PMID: 33442682 PMCID: PMC7805439 DOI: 10.1101/2021.01.03.425167] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The long noncoding RNA (lncRNA) XIST establishes X chromosome inactivation (XCI) in female cells in early development and thereafter is thought to be largely dispensable. Here we show XIST is continually required in adult human B cells to silence a subset of X-linked immune genes such as TLR7 . XIST-dependent genes lack promoter DNA methylation and require continual XIST-dependent histone deacetylation. XIST RNA-directed proteomics and CRISPRi screen reveal distinctive somatic cell-specific XIST complexes, and identify TRIM28 that mediates Pol II pausing at promoters of X-linked genes in B cells. XIST dysregylation, reflected by escape of XIST-dependent genes, occurs in CD11c+ atypical memory B cells across single-cell transcriptome data in patients with female-biased autoimmunity and COVID-19 infection. XIST inactivation with TLR7 agonism suffices to promote isotype-switched atypical B cells. These results suggest cell-type-specific diversification of lncRNA-protein complexes increase lncRNA functionalities, and expand roles for XIST in sex-differences in biology and medicine. HIGHLIGHTS XIST prevents escape of genes with DNA hypomethylated promoters in B cells.XIST maintains X-inactivation through continuous deacetylation of H3K27ac.XIST ChIRP-MS and allelic CRISPRi screen reveal a B cell-specific XIST cofactor TRIM28.XIST loss and TLR7 stimulation promotes CD11c+ atypical B cell formation.
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22
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Trotman JB, Lee DM, Cherney RE, Kim SO, Inoue K, Schertzer MD, Bischoff SR, Cowley DO, Calabrese J. Elements at the 5' end of Xist harbor SPEN-independent transcriptional antiterminator activity. Nucleic Acids Res 2020; 48:10500-10517. [PMID: 32986830 PMCID: PMC7544216 DOI: 10.1093/nar/gkaa789] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Revised: 08/20/2020] [Accepted: 09/12/2020] [Indexed: 12/22/2022] Open
Abstract
The Xist lncRNA requires Repeat A, a conserved RNA element located in its 5' end, to induce gene silencing during X-chromosome inactivation. Intriguingly, Repeat A is also required for production of Xist. While silencing by Repeat A requires the protein SPEN, how Repeat A promotes Xist production remains unclear. We report that in mouse embryonic stem cells, expression of a transgene comprising the first two kilobases of Xist (Xist-2kb) causes transcriptional readthrough of downstream polyadenylation sequences. Readthrough required Repeat A and the ∼750 nucleotides downstream, did not require SPEN, and was attenuated by splicing. Despite associating with SPEN and chromatin, Xist-2kb did not robustly silence transcription, whereas a 5.5-kb Xist transgene robustly silenced transcription and read through its polyadenylation sequence. Longer, spliced Xist transgenes also induced robust silencing yet terminated efficiently. Thus, in contexts examined here, Xist requires sequence elements beyond its first two kilobases to robustly silence transcription, and the 5' end of Xist harbors SPEN-independent transcriptional antiterminator activity that can repress proximal cleavage and polyadenylation. In endogenous contexts, this antiterminator activity may help produce full-length Xist RNA while rendering the Xist locus resistant to silencing by the same repressive complexes that the lncRNA recruits to other genes.
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Affiliation(s)
- Jackson B Trotman
- Department of Pharmacology and Lineberger Comprehensive Cancer Center, Chapel Hill, NC 27599, USA
| | - David M Lee
- Department of Pharmacology and Lineberger Comprehensive Cancer Center, Chapel Hill, NC 27599, USA
- Curriculum in Genetics and Molecular Biology, Chapel Hill, NC 27599, USA
| | - Rachel E Cherney
- Department of Pharmacology and Lineberger Comprehensive Cancer Center, Chapel Hill, NC 27599, USA
- Curriculum in Genetics and Molecular Biology, Chapel Hill, NC 27599, USA
| | - Susan O Kim
- Department of Pharmacology and Lineberger Comprehensive Cancer Center, Chapel Hill, NC 27599, USA
| | - Kaoru Inoue
- Department of Pharmacology and Lineberger Comprehensive Cancer Center, Chapel Hill, NC 27599, USA
| | - Megan D Schertzer
- Department of Pharmacology and Lineberger Comprehensive Cancer Center, Chapel Hill, NC 27599, USA
- Curriculum in Genetics and Molecular Biology, Chapel Hill, NC 27599, USA
| | - Steven R Bischoff
- Animal Models Core, University of North Carolina at Chapel Hill, 120 Mason Farm Road, Chapel Hill, NC 27599, USA
| | - Dale O Cowley
- Animal Models Core, University of North Carolina at Chapel Hill, 120 Mason Farm Road, Chapel Hill, NC 27599, USA
| | - J Mauro Calabrese
- Department of Pharmacology and Lineberger Comprehensive Cancer Center, Chapel Hill, NC 27599, USA
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23
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Ntini E, Marsico A. Functional impacts of non-coding RNA processing on enhancer activity and target gene expression. J Mol Cell Biol 2020; 11:868-879. [PMID: 31169884 PMCID: PMC6884709 DOI: 10.1093/jmcb/mjz047] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Revised: 04/03/2019] [Accepted: 04/04/2019] [Indexed: 01/06/2023] Open
Abstract
Tight regulation of gene expression is orchestrated by enhancers. Through recent research advancements, it is becoming clear that enhancers are not solely distal regulatory elements harboring transcription factor binding sites and decorated with specific histone marks, but they rather display signatures of active transcription, showing distinct degrees of transcription unit organization. Thereby, a substantial fraction of enhancers give rise to different species of non-coding RNA transcripts with an unprecedented range of potential functions. In this review, we bring together data from recent studies indicating that non-coding RNA transcription from active enhancers, as well as enhancer-produced long non-coding RNA transcripts, may modulate or define the functional regulatory potential of the cognate enhancer. In addition, we summarize supporting evidence that RNA processing of the enhancer-associated long non-coding RNA transcripts may constitute an additional layer of regulation of enhancer activity, which contributes to the control and final outcome of enhancer-targeted gene expression.
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Affiliation(s)
- Evgenia Ntini
- Max Planck Institute for Molecular Genetics, Berlin, Germany.,Free University Berlin, Berlin, Germany
| | - Annalisa Marsico
- Max Planck Institute for Molecular Genetics, Berlin, Germany.,Free University Berlin, Berlin, Germany.,Institute of Computational Biology, Helmholtz Zentrum München, München, Germany
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24
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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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25
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Coker H, Wei G, Moindrot B, Mohammed S, Nesterova T, Brockdorff N. The role of the Xist 5' m6A region and RBM15 in X chromosome inactivation. Wellcome Open Res 2020; 5:31. [PMID: 32258426 PMCID: PMC7097882 DOI: 10.12688/wellcomeopenres.15711.1] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/07/2020] [Indexed: 12/14/2022] Open
Abstract
Background: X chromosome inactivation in mammals is regulated by the non-coding (nc) RNA, Xist, which represses the chromosome from which it is transcribed. High levels of the N6-methyladenosine (m6A) RNA modification occur within Xist exon I, close to the 5' end of the transcript, and also further 3', in Xist exon VII. The m6A modification is catalysed by the METTL3/14 complex that is directed to specific targets, including Xist, by the RNA binding protein RBM15/15B. m6A modification of Xist RNA has been reported to be important for Xist-mediated gene silencing. Methods: We use CRISPR/Cas9 mediated mutagenesis to delete sequences around the 5' m6A region in interspecific XX mouse embryonic stem cells (mESCs). Following induction of Xist RNA expression, we assay chromosome silencing using allelic RNA-seq and Xist m6A distribution using m6A-seq. Additionally, we use Xist RNA FISH to analyse the effect of deleting the 5' m6A region on the function of the endogenous Xist promoter. We purify epitope tagged RBM15 from mESCs, and then apply MS/MS analysis to define the RBM15 interactome. Results: We show that a deletion encompassing the entire Xist 5' m6A region results in a modest reduction in Xist-mediated silencing, and that the 5' m6A region overlaps essential DNA elements required for activation of the endogenous Xist promoter. Deletion of the Xist A-repeat, to which RBM15 binds, entirely abolishes deposition of m6A in the Xist 5' m6A region without affecting the modification in exon VII. We show that in mESCs, RBM15 interacts with the m6A complex, the SETD1B histone modifying complex, and several proteins linked to RNA metabolism. Conclusions: Our findings support that RBM15 binding to the Xist A-repeat recruits the m6A complex to the 5' Xist m6A region and that this region plays a role in Xist-mediated chromosome silencing.
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Affiliation(s)
- Heather Coker
- Developmental Epigenetics, Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK
| | - Guifeng Wei
- Developmental Epigenetics, Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK
| | - Benoit Moindrot
- Developmental Epigenetics, Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), Gif-sur-Yvette, 91198, France
| | - Shabaz Mohammed
- Proteomics Technology Development and Application, Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK
| | - Tatyana Nesterova
- Developmental Epigenetics, Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK
| | - Neil Brockdorff
- Developmental Epigenetics, Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK
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26
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Yao B, Liang M, Liu H, Sui T, Song Y, Zhang Y, Deng J, Xu Y, Lai L, Li Z. The minimal promoter (P1) of Xist is non-essential for X chromosome inactivation. RNA Biol 2020; 17:623-629. [PMID: 32036747 DOI: 10.1080/15476286.2020.1725725] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
Abstract
The previous report shows the minimal promoter (P1) contributes to the Xist RNA activation in cells, while the role of the Xist P1 has not yet been investigated in animal individuals. Here, female Xist P1 knockout rabbits (Xist P1-/-) were generated for the studies. The results showed that there is no significant difference in transmission ratio, Xist and X-linked genes expression, and Xist RNA localization between the female wild type (WT) and Xist P1-/- rabbits, suggesting that P1 is non-essential for Xist expression and XCI in rabbits. Our study has explored the function of Xist P1 in animal level for the first time, and the results provide new ideas for future studies of XCI mechanisms.
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Affiliation(s)
- Bing Yao
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Animal Science, Jilin University, Changchun, China
| | - Mingming Liang
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Animal Science, Jilin University, Changchun, China
| | - Hongmei Liu
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Animal Science, Jilin University, Changchun, China
| | - Tingting Sui
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Animal Science, Jilin University, Changchun, China
| | - Yuning Song
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Animal Science, Jilin University, Changchun, China
| | - Yuxin Zhang
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Animal Science, Jilin University, Changchun, China
| | - Jichao Deng
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Animal Science, Jilin University, Changchun, China
| | - Yuxin Xu
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Animal Science, Jilin University, Changchun, China
| | - Liangxue Lai
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Animal Science, Jilin University, Changchun, China.,CAS Key Laboratory of Regenerative Biology, Guangdong Provincial Key Laboratory of Stem Cell and Regenerative Medicine, South China Institute for Stem Cell Biology and Regenerative Medicine, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou, China.,Guangzhou Regenerative Medicine and Health Guang Dong Laboratory (GRMH-GDL), Guangzhou, China.,Institute for Stem Cell and Regeneration, Chinese Academy of Sciences, Beijing, China
| | - Zhanjun Li
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Animal Science, Jilin University, Changchun, China
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27
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28
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Fukuda A, Motosugi N, Ando M, Kimura M, Umezawa A, Akutsu H. Imprinted X-chromosome inactivation impacts primitive endoderm differentiation in mouse blastocysts. FEBS Lett 2019; 594:913-923. [PMID: 31721177 DOI: 10.1002/1873-3468.13676] [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: 07/19/2019] [Revised: 10/29/2019] [Accepted: 11/03/2019] [Indexed: 11/05/2022]
Abstract
Epigenetic and transcriptome alterations are essential for lineage specification, represented by imprinted X-chromosome inactivation (iXCI) in female mouse preimplantation embryos. However, how various factors affect transcriptome states and lineage commitment remains unclear. We found that in vitro culture duration strongly influences transcriptional variation compared to iXCI loss. Single-cell analysis of the inner cell mass (ICM) for major transcription and epigenomic factors revealed that sex-specific differences in expression are diminished by loss of iXCI in the primitive endoderm (PrE) but not in the epiblast. Females had a higher proportion of ICM compared to that in males, and PrE development was affected by iXCI states in female embryos. Our findings provide insight into sex differences and iXCI function in lineage specification.
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Affiliation(s)
- Atsushi Fukuda
- Medical Division, Institute of Innovative Science and Technology, Tokai University, Isehara, Japan.,Center for Regenerative Medicine, National Center for Child Health and Development, Tokyo, Japan
| | - Nami Motosugi
- Medical Division, Institute of Innovative Science and Technology, Tokai University, Isehara, Japan
| | - Mikiko Ando
- Medical Division, Institute of Innovative Science and Technology, Tokai University, Isehara, Japan
| | - Minoru Kimura
- Institute of Medical Sciences, Tokai University, Isehara, Japan
| | - Akihiro Umezawa
- Center for Regenerative Medicine, National Center for Child Health and Development, Tokyo, Japan
| | - Hidenori Akutsu
- Center for Regenerative Medicine, National Center for Child Health and Development, Tokyo, Japan
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29
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Bousard A, Raposo AC, Żylicz JJ, Picard C, Pires VB, Qi Y, Gil C, Syx L, Chang HY, Heard E, da Rocha ST. The role of Xist-mediated Polycomb recruitment in the initiation of X-chromosome inactivation. EMBO Rep 2019; 20:e48019. [PMID: 31456285 PMCID: PMC6776897 DOI: 10.15252/embr.201948019] [Citation(s) in RCA: 64] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Revised: 07/29/2019] [Accepted: 08/06/2019] [Indexed: 12/22/2022] Open
Abstract
Xist RNA has been established as the master regulator of X-chromosome inactivation (XCI) in female eutherian mammals, but its mechanism of action remains unclear. By creating novel Xist-inducible mutants at the endogenous locus in male mouse embryonic stem (ES) cells, we dissect the role of the conserved A-B-C-F repeats in the initiation of XCI. We find that transcriptional silencing can be largely uncoupled from Polycomb repressive complex 1 and complex 2 (PRC1/2) recruitment, which requires B and C repeats. Xist ΔB+C RNA specifically loses interaction with PCGF3/5 subunits of PRC1, while binding of other Xist partners is largely unaffected. However, a slight relaxation of transcriptional silencing in Xist ΔB+C indicates a role for PRC1/2 proteins in early stabilization of gene repression. Distinct modules within the Xist RNA are therefore involved in the convergence of independent chromatin modification and gene repression pathways. In this context, Polycomb recruitment seems to be of moderate relevance in the initiation of silencing.
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Affiliation(s)
- Aurélie Bousard
- Mammalian Developmental Epigenetics GroupInstitut CurieCNRS UMR3215, INSERM U934PSL UniversityParisFrance
| | - Ana Cláudia Raposo
- Instituto de Medicina MolecularJoão Lobo AntunesFaculdade de MedicinaUniversidade de LisboaLisboaPortugal
| | - Jan Jakub Żylicz
- Mammalian Developmental Epigenetics GroupInstitut CurieCNRS UMR3215, INSERM U934PSL UniversityParisFrance
- Department of Physiology, Development and NeuroscienceUniversity of CambridgeCambridgeUK
| | - Christel Picard
- Mammalian Developmental Epigenetics GroupInstitut CurieCNRS UMR3215, INSERM U934PSL UniversityParisFrance
| | - Vanessa Borges Pires
- Instituto de Medicina MolecularJoão Lobo AntunesFaculdade de MedicinaUniversidade de LisboaLisboaPortugal
- Instituto de Ciências Biomédicas Abel SalazarUniversidade do PortoPortoPortugal
| | - Yanyan Qi
- Center for Dynamic Personal RegulomesStanford UniversityStanfordCAUSA
| | - Cláudia Gil
- Instituto de Medicina MolecularJoão Lobo AntunesFaculdade de MedicinaUniversidade de LisboaLisboaPortugal
| | - Laurène Syx
- Mammalian Developmental Epigenetics GroupInstitut CurieCNRS UMR3215, INSERM U934PSL UniversityParisFrance
| | - Howard Y Chang
- Center for Dynamic Personal RegulomesStanford UniversityStanfordCAUSA
- Howard Hughes Medical InstituteStanford UniversityStanfordCAUSA
| | - Edith Heard
- Mammalian Developmental Epigenetics GroupInstitut CurieCNRS UMR3215, INSERM U934PSL UniversityParisFrance
| | - Simão Teixeira da Rocha
- Mammalian Developmental Epigenetics GroupInstitut CurieCNRS UMR3215, INSERM U934PSL UniversityParisFrance
- Instituto de Medicina MolecularJoão Lobo AntunesFaculdade de MedicinaUniversidade de LisboaLisboaPortugal
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30
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Abstract
In mammals, dosage compensation of sex chromosomal genes between females (XX) and males (XY) is achieved through X-chromosome inactivation (XCI). The X-linked X-inactive-specific transcript (Xist) long noncoding RNA is indispensable for XCI and initiates the process early during development by spreading in cis across the X chromosome from which it is transcribed. During XCI, Xist RNA triggers gene silencing, recruits a plethora of chromatin modifying factors, and drives a major structural reorganization of the X chromosome. Here, we review our knowledge of the multitude of epigenetic events orchestrated by Xist RNA to allow female mammals to survive through embryonic development by establishing and maintaining proper dosage compensation. In particular, we focus on recent studies characterizing the interaction partners of Xist RNA, and we discuss how they have affected the field by addressing long-standing controversies or by giving rise to new research perspectives that are currently being explored. This review is dedicated to the memory of Denise Barlow, pioneer of genomic imprinting and functional long noncoding RNAs (lncRNAs), whose work has revolutionized the epigenetics field and continues to inspire generations of scientists.
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31
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Stork C, Li Z, Lin L, Zheng S. Developmental Xist induction is mediated by enhanced splicing. Nucleic Acids Res 2019; 47:1532-1543. [PMID: 30496473 PMCID: PMC6379716 DOI: 10.1093/nar/gky1198] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Revised: 11/12/2018] [Accepted: 11/15/2018] [Indexed: 11/12/2022] Open
Abstract
X-inactive-specific transcript (Xist) is a long noncoding RNA (lncRNA) essential for inactivating one of the two X chromosomes in mammalian females. Random X chromosome inactivation is mediated by Xist RNA expressed from the inactive X chromosome. We found that Xist RNA is unspliced in naïve embryonic stem (ES) cells. Upon differentiation, Xist splicing becomes efficient across all exons independent of transcription, suggesting interdependent or coordinated removal of Xist introns. In female cells with mutated polypyrimidine tract binding protein 1 (Ptbp1), differentiation fails to substantially upregulate mature Xist RNA because of a defect in Xist splicing. We further found both Xist129 and XistCAS RNA are unspliced in Mus musculus 129SvJ/Mus castaneous (CAS) hybrid female ES cells. Upon differentiation, Xist129 exhibits a higher splicing efficiency than XistCAS, likely contributing to preferential inhibition of the X129 chromosome. Single cell analysis shows that the allelic choice of Xist splicing is linked to the inactive X chromosome. We conclude post-transcriptional control of Xist RNA splicing is an essential regulatory step of Xist induction. Our studies shed light on the developmental roles of splicing for nuclear-retained Xist lncRNA and suggest inefficient Xist splicing is an additional fail-safe mechanism to prevent Xist activity in ES cells.
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Affiliation(s)
- Cheryl Stork
- Graduate Program in Cell, Molecular and Developmental Biology, University of California, Riverside, Riverside, CA 92521, USA
| | - Zhelin Li
- Graduate Program in Genetics, Genomics and Bioinformatics, University of California, Riverside, Riverside, CA 92521, USA
| | - Lin Lin
- Division of Biomedical Sciences, University of California, Riverside, Riverside, CA 92521, USA
| | - Sika Zheng
- Graduate Program in Cell, Molecular and Developmental Biology, University of California, Riverside, Riverside, CA 92521, USA.,Graduate Program in Genetics, Genomics and Bioinformatics, University of California, Riverside, Riverside, CA 92521, USA.,Division of Biomedical Sciences, University of California, Riverside, Riverside, CA 92521, USA
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32
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Sprague D, Waters SA, Kirk JM, Wang JR, Samollow PB, Waters PD, Calabrese JM. Nonlinear sequence similarity between the Xist and Rsx long noncoding RNAs suggests shared functions of tandem repeat domains. RNA (NEW YORK, N.Y.) 2019; 25:1004-1019. [PMID: 31097619 PMCID: PMC6633197 DOI: 10.1261/rna.069815.118] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Accepted: 05/14/2019] [Indexed: 05/30/2023]
Abstract
The marsupial inactive X chromosome expresses a long noncoding RNA (lncRNA) called Rsx that has been proposed to be the functional analog of eutherian Xist Despite the possibility that Xist and Rsx encode related functions, the two lncRNAs harbor no linear sequence similarity. However, both lncRNAs harbor domains of tandemly repeated sequence. In Xist, these repeat domains are known to be critical for function. Using k-mer based comparison, we show that the repeat domains of Xist and Rsx unexpectedly partition into two major clusters that each harbor substantial levels of nonlinear sequence similarity. Xist Repeats B, C, and D were most similar to each other and to Rsx Repeat 1, whereas Xist Repeats A and E were most similar to each other and to Rsx Repeats 2, 3, and 4. Similarities at the level of k-mers corresponded to domain-specific enrichment of protein-binding motifs. Within individual domains, protein-binding motifs were often enriched to extreme levels. Our data support the hypothesis that Xist and Rsx encode similar functions through different spatial arrangements of functionally analogous protein-binding domains. We propose that the two clusters of repeat domains in Xist and Rsx function in part to cooperatively recruit PRC1 and PRC2 to chromatin. The physical manner in which these domains engage with protein cofactors may be just as critical to the function of the domains as the protein cofactors themselves. The general approaches we outline in this report should prove useful in the study of any set of RNAs.
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Affiliation(s)
- Daniel Sprague
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
- Curriculum in Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
| | - Shafagh A Waters
- School of Biotechnology and Biomolecular Sciences, Faculty of Science, University of New South Wales, Sydney, New South Wales 2052, Australia
- School of Women's and Children's Health, Faculty of Medicine, University of New South Wales, Sydney, New South Wales 2052, Australia
| | - Jessime M Kirk
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
- Curriculum in Bioinformatics and Computational Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
| | - Jeremy R Wang
- Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
| | - Paul B Samollow
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, Texas 77843, USA
| | - Paul D Waters
- School of Biotechnology and Biomolecular Sciences, Faculty of Science, University of New South Wales, Sydney, New South Wales 2052, Australia
| | - J Mauro Calabrese
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
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33
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Lee DM, Trotman JB, Cherney RE, Inoue K, Schertzer MD, Bischoff SR, Cowley DO, Calabrese JM. RETRACTED: A 5' fragment of Xist can sequester RNA produced from adjacent genes on chromatin. Nucleic Acids Res 2019; 47:7049-7062. [PMID: 31114903 PMCID: PMC6648342 DOI: 10.1093/nar/gkz432] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2019] [Revised: 04/18/2019] [Accepted: 05/09/2019] [Indexed: 12/15/2022] Open
Abstract
Xist requires Repeat-A, a protein-binding module in its first two kilobases (2kb), to repress transcription. We report that when expressed as a standalone transcript in mouse embryonic stem cells (ESCs), the first 2kb of Xist (Xist-2kb) does not induce transcriptional silencing. Instead, Xist-2kb sequesters RNA produced from adjacent genes on chromatin. Sequestration does not spread beyond adjacent genes, requires the same sequence elements in Repeat-A that full-length Xist requires to repress transcription and can be induced by lncRNAs with similar sequence composition to Xist-2kb. We did not detect sequestration by full-length Xist, but we did detect it by mutant forms of Xist with attenuated transcriptional silencing capability. Xist-2kb associated with SPEN, a Repeat-A binding protein required for Xist-induced transcriptional silencing, but SPEN was not necessary for sequestration. Thus, when expressed in mouse ESCs, a 5' fragment of Xist that contains Repeat-A sequesters RNA from adjacent genes on chromatin and associates with the silencing factor SPEN, but it does not induce transcriptional silencing. Instead, Xist-induced transcriptional silencing requires synergy between Repeat-A and additional sequence elements in Xist. We propose that sequestration is mechanistically related to the Repeat-A dependent stabilization and tethering of Xist near actively transcribed regions of chromatin.
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Affiliation(s)
- David M Lee
- Department of Pharmacology and Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599, USA
- Curriculum in Genetics and Molecular Biology, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Jackson B Trotman
- Department of Pharmacology and Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Rachel E Cherney
- Department of Pharmacology and Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599, USA
- Curriculum in Genetics and Molecular Biology, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Kaoru Inoue
- Department of Pharmacology and Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Megan D Schertzer
- Department of Pharmacology and Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599, USA
- Curriculum in Genetics and Molecular Biology, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Steven R Bischoff
- Animal Models Core, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Dale O Cowley
- Animal Models Core, University of North Carolina, Chapel Hill, NC 27599, USA
| | - J Mauro Calabrese
- Department of Pharmacology and Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599, USA
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34
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Yue M, Ogawa Y. CRISPR/Cas9-mediated modulation of splicing efficiency reveals short splicing isoform of Xist RNA is sufficient to induce X-chromosome inactivation. Nucleic Acids Res 2019; 46:e26. [PMID: 29237010 PMCID: PMC5861412 DOI: 10.1093/nar/gkx1227] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Accepted: 11/29/2017] [Indexed: 12/11/2022] Open
Abstract
Alternative splicing of mRNA precursors results in multiple protein variants from a single gene and is critical for diverse cellular processes and development. Xist encodes a long noncoding RNA which is a central player to induce X-chromosome inactivation in female mammals and has two major splicing variants: long and short isoforms of Xist RNA. Although a differentiation-specific and a female-specific expression of Xist isoforms have been reported, the functional role of each Xist RNA isoform is largely unexplored. Using CRISPR/Cas9-mediated targeted modification of the 5' splice site in Xist intron 7, we create mutant female ES cell lines which dominantly express the long- or short-splicing isoform of Xist RNA from the inactive X-chromosome (Xi) upon differentiation. Successful execution of CRISPR/Cas-based splicing modulation indicates that our CRISPR/Cas-based targeted modification of splicing sites is a useful approach to study specific isoforms of a transcript generated by alternative splicing. Upon differentiation of splicing-mutant Xist female ES cells, we find that both long and short Xist isoforms can induce X-chromosome inactivation normally during ES cell differentiation, suggesting that the short splicing isoform of Xist RNA is sufficient to induce X-chromosome inactivation.
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Affiliation(s)
- Minghui Yue
- Division of Reproductive Sciences, Division of Developmental Biology, Perinatal Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA.,Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA
| | - Yuya Ogawa
- Division of Reproductive Sciences, Division of Developmental Biology, Perinatal Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA.,Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA
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35
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Abstract
X chromosome inactivation silences one X chromosome in female mammals. However, this silencing is incomplete, and some genes escape X inactivation. We describe methods to determine the chromosome-wide X inactivation status of genes in tissues or cell lines derived from mice using a combination of skewing of X inactivation and allele-specific analyses of gene expression based on RNA-seq.
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36
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Karami K, Zerehdaran S, Javadmanesh A, Shariati MM, Fallahi H. Characterization of bovine (Bos taurus) imprinted genes from genomic to amino acid attributes by data mining approaches. PLoS One 2019; 14:e0217813. [PMID: 31170205 PMCID: PMC6553745 DOI: 10.1371/journal.pone.0217813] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2018] [Accepted: 05/21/2019] [Indexed: 01/05/2023] Open
Abstract
Genomic imprinting results in monoallelic expression of genes in mammals and flowering plants. Understanding the function of imprinted genes improves our knowledge of the regulatory processes in the genome. In this study, we have employed classification and clustering algorithms with attribute weighting to specify the unique attributes of both imprinted (monoallelic) and biallelic expressed genes. We have obtained characteristics of 22 known monoallelically expressed (imprinted) and 8 biallelic expressed genes that have been experimentally validated alongside 208 randomly selected genes in bovine (Bos taurus). Attribute weighting methods and various supervised and unsupervised algorithms in machine learning were applied. Unique characteristics were discovered and used to distinguish mono and biallelic expressed genes from each other in bovine. To obtain the accuracy of classification, 10-fold cross-validation with concerning each combination of attribute weighting (feature selection) and machine learning algorithms, was used. Our approach was able to accurately predict mono and biallelic genes using the genomics and proteomics attributes.
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Affiliation(s)
- Keyvan Karami
- Department of Animal Science, Faculty of Agriculture, Ferdowsi University of Mashhad, Mashhad, Iran
| | - Saeed Zerehdaran
- Department of Animal Science, Faculty of Agriculture, Ferdowsi University of Mashhad, Mashhad, Iran
| | - Ali Javadmanesh
- Department of Animal Science, Faculty of Agriculture, Ferdowsi University of Mashhad, Mashhad, Iran
| | - Mohammad Mahdi Shariati
- Department of Animal Science, Faculty of Agriculture, Ferdowsi University of Mashhad, Mashhad, Iran
| | - Hossein Fallahi
- Department of Biology, School of Sciences, Razi University, Kermanshah, Iran
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37
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Loss of p53 Causes Stochastic Aberrant X-Chromosome Inactivation and Female-Specific Neural Tube Defects. Cell Rep 2019; 27:442-454.e5. [DOI: 10.1016/j.celrep.2019.03.048] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Revised: 02/11/2019] [Accepted: 03/13/2019] [Indexed: 12/13/2022] Open
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38
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Colognori D, Sunwoo H, Kriz AJ, Wang CY, Lee JT. Xist Deletional Analysis Reveals an Interdependency between Xist RNA and Polycomb Complexes for Spreading along the Inactive X. Mol Cell 2019; 74:101-117.e10. [PMID: 30827740 DOI: 10.1016/j.molcel.2019.01.015] [Citation(s) in RCA: 104] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Revised: 11/21/2018] [Accepted: 01/10/2019] [Indexed: 12/16/2022]
Abstract
During X-inactivation, Xist RNA spreads along an entire chromosome to establish silencing. However, the mechanism and functional RNA elements involved in spreading remain undefined. By performing a comprehensive endogenous Xist deletion screen, we identify Repeat B as crucial for spreading Xist and maintaining Polycomb repressive complexes 1 and 2 (PRC1/PRC2) along the inactive X (Xi). Unexpectedly, spreading of these three factors is inextricably linked. Deleting Repeat B or its direct binding partner, HNRNPK, compromises recruitment of PRC1 and PRC2. In turn, ablating PRC1 or PRC2 impairs Xist spreading. Therefore, Xist and Polycomb complexes require each other to propagate along the Xi, suggesting a positive feedback mechanism between RNA initiator and protein effectors. Perturbing Xist/Polycomb spreading causes failure of de novo Xi silencing, with partial compensatory downregulation of the active X, and also disrupts topological Xi reconfiguration. Thus, Repeat B is a multifunctional element that integrates interdependent Xist/Polycomb spreading, silencing, and changes in chromosome architecture.
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Affiliation(s)
- David Colognori
- Howard Hughes Medical Institute; Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114, USA; Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Hongjae Sunwoo
- Howard Hughes Medical Institute; Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114, USA; Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Andrea J Kriz
- Howard Hughes Medical Institute; Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114, USA; Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Chen-Yu Wang
- Howard Hughes Medical Institute; Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114, USA; Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Jeannie T Lee
- Howard Hughes Medical Institute; Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114, USA; Department of Genetics, Harvard Medical School, Boston, MA 02115, USA.
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39
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Abstract
Despite essential roles played by long noncoding RNAs (lncRNAs) in development and disease, methods to determine lncRNA cis-elements are lacking. Here, we developed a screening method named “Tiling CRISPR” to identify lncRNA functional domains. Using this approach, we identified Xist A-Repeats as the silencing domain, an observation in agreement with published work, suggesting Tiling CRISPR feasibility. Mechanistic analysis suggested a novel function for Xist A-repeats in promoting Xist transcription. Overall, our method allows mapping of lncRNA functional domains in an unbiased and potentially high-throughput manner to facilitate the understanding of lncRNA functions.
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40
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Sakakibara Y, Nagao K, Blewitt M, Sasaki H, Obuse C, Sado T. Role of SmcHD1 in establishment of epigenetic states required for the maintenance of the X-inactivated state in mice. Development 2018; 145:dev.166462. [PMID: 30126901 DOI: 10.1242/dev.166462] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2018] [Accepted: 08/10/2018] [Indexed: 01/01/2023]
Abstract
X inactivation in mammals is regulated by epigenetic modifications. Functional deficiency of SmcHD1 has been shown to cause de-repression of X-inactivated genes in post-implantation female mouse embryos, suggesting a role of SmcHD1 in the maintenance of X inactivation. Here, we show that de-repression of X-inactivated genes accompanied a local reduction in the enrichment of H3K27me3 in mouse embryonic fibroblasts deficient for SmcHD1. Furthermore, many of these genes overlapped with those having a significantly lower enrichment of H3K27me3 at the blastocyst stage in wild type. Intriguingly, however, depletion of SmcHD1 did not compromise the X-inactivated state in immortalized female mouse embryonic fibroblasts, in which X inactivation had been established and maintained. Taking all these findings together, we suggest that SmcHD1 facilitates the incorporation of H3K27me3 and perhaps other epigenetic modifications at gene loci that are silenced even with the lower enrichment of H3K27me3 at the early stage of X inactivation. The epigenetic state at these loci would, however, remain as it is at the blastocyst stage in the absence of SmcHD1 after implantation, which would eventually compromise the maintenance of the X-inactivated state at later stages.
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Affiliation(s)
- Yuki Sakakibara
- Medical Institute of Bioregulation, Kyushu University, 3-1-1, Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan
| | - Koji Nagao
- Department of Biological Science, Graduate School of Science, Osaka University, Toyonaka, Japan
| | - Marnie Blewitt
- The Walter and Eliza Hall Institute of Medical Research, 1G Royal Pde, Parkville 3052 VIC, Australia; The Department of Medical Biology, University of Melbourne, Parkville 3052, VIC, Australia
| | - Hiroyuki Sasaki
- Medical Institute of Bioregulation, Kyushu University, 3-1-1, Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan
| | - Chikashi Obuse
- Department of Biological Science, Graduate School of Science, Osaka University, Toyonaka, Japan
| | - Takashi Sado
- Medical Institute of Bioregulation, Kyushu University, 3-1-1, Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan .,Department of Advanced Bioscience, Graduate School of Agriculture, Kindai University, 3327-204, Nakamachi, Nara, 630-8505, Japan
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41
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Adrianse RL, Smith K, Gatbonton-Schwager T, Sripathy SP, Lao U, Foss EJ, Boers RG, Boers JB, Gribnau J, Bedalov A. Perturbed maintenance of transcriptional repression on the inactive X-chromosome in the mouse brain after Xist deletion. Epigenetics Chromatin 2018; 11:50. [PMID: 30170615 PMCID: PMC6118007 DOI: 10.1186/s13072-018-0219-8] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2018] [Accepted: 08/16/2018] [Indexed: 01/22/2023] Open
Abstract
Background The long noncoding RNA Xist is critical for initiation and establishment of X-chromosome inactivation during embryogenesis in mammals, but it is unclear whether its continued expression is required for maintaining X-inactivation in vivo. Results By using an inactive X-chromosome-linked MeCP2-GFP reporter, which allowed us to enumerate reactivation events in the mouse brain even when they occur in very few cells, we found that deletion of Xist in the brain after establishment of X-chromosome inactivation leads to reactivation in 2–5% of neurons and in a smaller fraction of astrocytes. In contrast to global loss of both H3 lysine 27 trimethylation (H3K27m3) and histone H2A lysine 119 monoubiquitylation (H2AK119ub1) we observed upon Xist deletion, alterations in CpG methylation were subtle, and this was mirrored by only minor alterations in X-chromosome-wide gene expression levels, with highly expressed genes more prone to both derepression and demethylation compared to genes with low expression level. Conclusion Our results demonstrate that Xist plays a role in the maintenance of histone repressive marks, DNA methylation and transcriptional repression on the inactive X-chromosome, but that partial loss of X-dosage compensation in the absence of Xist in the brain is well tolerated. Electronic supplementary material The online version of this article (10.1186/s13072-018-0219-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Robin L Adrianse
- Clinical Research Division, Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue N., Seattle, WA, 98109, USA
| | - Kaleb Smith
- Clinical Research Division, Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue N., Seattle, WA, 98109, USA
| | - Tonibelle Gatbonton-Schwager
- Clinical Research Division, Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue N., Seattle, WA, 98109, USA
| | - Smitha P Sripathy
- Clinical Research Division, Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue N., Seattle, WA, 98109, USA
| | - Uyen Lao
- Clinical Research Division, Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue N., Seattle, WA, 98109, USA
| | - Eric J Foss
- Clinical Research Division, Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue N., Seattle, WA, 98109, USA
| | - Ruben G Boers
- Department of Developmental Biology, Erasmus MC, 3015 CN, Rotterdam, The Netherlands.,Department of Obstetrics and Gynaecology, Erasmus MC, 3015 CN, Rotterdam, The Netherlands
| | - Joachim B Boers
- Department of Developmental Biology, Erasmus MC, 3015 CN, Rotterdam, The Netherlands.,Delft Diagnostic Laboratories, 2288 ER, Rijswijk, The Netherlands
| | - Joost Gribnau
- Department of Developmental Biology, Erasmus MC, 3015 CN, Rotterdam, The Netherlands
| | - Antonio Bedalov
- Clinical Research Division, Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue N., Seattle, WA, 98109, USA. .,Department of Biochemistry, University of Washington, Seattle, WA, 98195, USA. .,Department of Medicine, University of Washington, Seattle, WA, 98195, USA.
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42
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Monfort A, Wutz A. Progress in understanding the molecular mechanism of Xist RNA function through genetics. Philos Trans R Soc Lond B Biol Sci 2018; 372:rstb.2016.0368. [PMID: 28947663 DOI: 10.1098/rstb.2016.0368] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/09/2017] [Indexed: 01/06/2023] Open
Abstract
The Xist gene produces a long noncoding RNA that initiates chromosome-wide gene repression on the inactive X chromosome in female mammals. Recent progress has advanced the understanding of Xist function at the molecular level. This review provides an overview of insights from genetic approaches and puts the new data in the context of an emerging mechanistic model as well as the existing literature. Some consideration is given on how independent biochemical studies on X inactivation help to advance on the wider question of chromatin regulation in the mammalian dosage compensation system.This article is part of the themed issue 'X-chromosome inactivation: a tribute to Mary Lyon'.
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Affiliation(s)
- Asun Monfort
- Institute of Molecular Health Sciences, Department of Biology, Swiss Federal Institute of Technology, ETH Hönggerberg, Otto-Stern-Weg 7, 8049 Zurich, Switzerland
| | - Anton Wutz
- Institute of Molecular Health Sciences, Department of Biology, Swiss Federal Institute of Technology, ETH Hönggerberg, Otto-Stern-Weg 7, 8049 Zurich, Switzerland
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43
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Sakata Y, Nagao K, Hoki Y, Sasaki H, Obuse C, Sado T. Defects in dosage compensation impact global gene regulation in the mouse trophoblast. Development 2017; 144:2784-2797. [PMID: 28684628 DOI: 10.1242/dev.149138] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2017] [Accepted: 06/27/2017] [Indexed: 12/11/2022]
Abstract
Xist RNA, which is responsible for X inactivation, is a key epigenetic player in the embryogenesis of female mammals. Of the several repeats conserved in Xist RNA, the A-repeat has been shown to be essential for its silencing function in differentiating embryonic stem cells. Here, we introduced a new Xist allele into mouse that produces mutated Xist RNA lacking the A-repeat (XistCAGΔ5' ). XistCAGΔ5' RNA expressed in the embryo coated the X chromosome but failed to silence it. Although imprinted X inactivation was substantially compromised upon paternal transmission, allele-specific RNA-seq in the trophoblast revealed that XistCAGΔ5' RNA still retained some silencing ability. Furthermore, the failure of imprinted X inactivation had more significant impacts than expected on genome-wide gene expression. It is likely that dosage compensation is required not only for equalizing X-linked gene expression between the sexes but also for proper global gene regulation in differentiated female somatic cells.
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Affiliation(s)
- Yuka Sakata
- Department of Bioscience, Graduate School of Agriculture, Kindai University, 3327-204, Nakamachi, Nara 631-8505, Japan.,Division of Epigenomics, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Koji Nagao
- Graduate School of Life Science, Hokkaido University, Sapporo, Hokkaido 001-0021, Japan.,Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
| | - Yuko Hoki
- Division of Epigenomics, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Hiroyuki Sasaki
- Division of Epigenomics, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Chikashi Obuse
- Graduate School of Life Science, Hokkaido University, Sapporo, Hokkaido 001-0021, Japan.,Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
| | - Takashi Sado
- Department of Bioscience, Graduate School of Agriculture, Kindai University, 3327-204, Nakamachi, Nara 631-8505, Japan .,Division of Epigenomics, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
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44
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Abstract
Nucleus is the residence and place of work for a plethora of long noncoding RNAs. Here, we provide a summary of the functions and functional mechanisms of several relatively well studied examples of nuclear long noncoding RNAs (lncRNAs) in the nucleus, such as Xist, NEAT1, MALAT1 and TERRA. The recently identified novel EIciRNA is also highlighted. These nuclear lncRNAs play a variety of roles with diverse molecular mechanisms in animal cells. We also discuss insights and concerns about current and future studies of nuclear lnc RNAs.
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Affiliation(s)
- Bin Yu
- a The CAS Key Laboratory of Innate Immunity and Chronic Disease , CAS Center for Excellence in Molecular Cell Science , School of Life Sciences , University of Science and Technology of China , Hefei , Anhui Province , China
| | - Ge Shan
- a The CAS Key Laboratory of Innate Immunity and Chronic Disease , CAS Center for Excellence in Molecular Cell Science , School of Life Sciences , University of Science and Technology of China , Hefei , Anhui Province , China
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45
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Allele-specific non-CG DNA methylation marks domains of active chromatin in female mouse brain. Proc Natl Acad Sci U S A 2017; 114:E2882-E2890. [PMID: 28320934 DOI: 10.1073/pnas.1611905114] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
DNA methylation at gene promoters in a CG context is associated with transcriptional repression, including at genes silenced on the inactive X chromosome in females. Non-CG methylation (mCH) is a distinct feature of the neuronal epigenome that is differentially distributed between males and females on the X chromosome. However, little is known about differences in mCH on the active (Xa) and inactive (Xi) X chromosomes because stochastic X-chromosome inactivation (XCI) confounds allele-specific epigenomic profiling. We used whole-genome bisulfite sequencing in a mouse model with nonrandom XCI to examine allele-specific DNA methylation in frontal cortex. Xi was largely devoid of mCH, whereas Xa contained abundant mCH similar to the male X chromosome and the autosomes. In contrast to the repressive association of DNA methylation at CG dinucleotides (mCG), mCH accumulates on Xi in domains with transcriptional activity, including the bodies of most genes that escape XCI and at the X-inactivation center, validating this epigenetic mark as a signature of transcriptional activity. Escape genes showing CH hypermethylation were the only genes with CG-hypomethylated promoters on Xi, a well-known mark of active transcription. Finally, we found extensive allele-specific mCH and mCG at autosomal imprinted regions, some with a negative correlation between methylation in the two contexts, further supporting their distinct functions. Our findings show that neuronal mCH functions independently of mCG and is a highly dynamic epigenomic correlate of allele-specific gene regulation.
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46
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Yang T, Yildirim E. Epigenetic and LncRNA-Mediated Regulation of X Chromosome Inactivation and Its Impact on Pathogenesis. CURRENT PATHOBIOLOGY REPORTS 2017. [DOI: 10.1007/s40139-017-0120-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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47
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Lv Q, Yuan L, Song Y, Sui T, Li Z, Lai L. D-repeat in the XIST gene is required for X chromosome inactivation. RNA Biol 2016; 13:172-6. [PMID: 26786668 DOI: 10.1080/15476286.2015.1137420] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
XIST is a long non-coding RNA, which expressed exclusively from the inactive X chromosome. Although it has been revealed that the A-repeat contributes to the X chromosome inactivation (X-inactivation), the role of the longest D-repeat has not yet been investigated. Here, a sgRNA directed CRISPR/Cas9 system which have multiple target sites within repeat D of XIST, were used to generate D-repeat deletion and studied its roles on X-inactivation. The results showed that the deletion of D-repeat caused a significantly decreased expression of XIST, and up regulated expression of X-linked genes, suggesting that the D-repeat may play an important role in the regulation of XIST expression and silencing of the X-linked genes, which could provide a new idea in the molecular mechanisms of X-inactivation.
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Affiliation(s)
- Qingyan Lv
- a Jilin Provincial Key Laboratory of Animal Embryo Engineering, Jilin University , Changchun , 130062 , China
| | - Lin Yuan
- a Jilin Provincial Key Laboratory of Animal Embryo Engineering, Jilin University , Changchun , 130062 , China
| | - Yuning Song
- a Jilin Provincial Key Laboratory of Animal Embryo Engineering, Jilin University , Changchun , 130062 , China
| | - Tingting Sui
- a Jilin Provincial Key Laboratory of Animal Embryo Engineering, Jilin University , Changchun , 130062 , China
| | - Zhanjun Li
- a Jilin Provincial Key Laboratory of Animal Embryo Engineering, Jilin University , Changchun , 130062 , China
| | - Liangxue Lai
- a Jilin Provincial Key Laboratory of Animal Embryo Engineering, Jilin University , Changchun , 130062 , China
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48
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Fukuda A, Mitani A, Miyashita T, Sado T, Umezawa A, Akutsu H. Maintenance of Xist Imprinting Depends on Chromatin Condensation State and Rnf12 Dosage in Mice. PLoS Genet 2016; 12:e1006375. [PMID: 27788132 PMCID: PMC5082930 DOI: 10.1371/journal.pgen.1006375] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2016] [Accepted: 09/20/2016] [Indexed: 12/30/2022] Open
Abstract
In female mammals, activation of Xist (X-inactive specific transcript) is essential for establishment of X chromosome inactivation. During early embryonic development in mice, paternal Xist is preferentially expressed whereas maternal Xist (Xm-Xist) is silenced. Unlike autosomal imprinted genes, Xist imprinting for Xm-Xist silencing was erased in cloned or parthenogenetic but not fertilized embryos. However, the molecular mechanism underlying the variable nature of Xm-Xist imprinting is poorly understood. Here, we revealed that Xm-Xist silencing depends on chromatin condensation states at the Xist/Tsix genomic region and on Rnf12 expression levels. In early preimplantation, chromatin decondensation via H3K9me3 loss and histone acetylation gain caused Xm-Xist derepression irrespective of embryo type. Although the presence of the paternal genome during pronuclear formation impeded Xm-Xist derepression, Xm-Xist was robustly derepressed when the maternal genome was decondensed before fertilization. Once Xm-Xist was derepressed by chromatin alterations, the derepression was stably maintained and rescued XmXpΔ lethality, indicating that loss of Xm-Xist imprinting was irreversible. In late preimplantation, Oct4 served as a chromatin opener to create transcriptional permissive states at Xm-Xist/Tsix genomic loci. In parthenogenetic embryos, Rnf12 overdose caused Xm-Xist derepression via Xm-Tsix repression; physiological Rnf12 levels were essential for Xm-Xist silencing maintenance in fertilized embryos. Thus, chromatin condensation and fine-tuning of Rnf12 dosage were crucial for Xist imprint maintenance by silencing Xm-Xist. X-inactive specific transcript (Xist) is essential a large non-coding RNA for establishment of X chromosome inactivation in female mammals. The aberrant X chromosome inactivation critically affects cellular viability. Therefore, spatiotemporal regulation of Xist expression is required for proper development. In mice, Xist expression is imprinted in early embryonic development and maternal Xist is never expressed during preimplantation phases irrespective of the presence of Xist activator, maternal Rnf12. Generally, parental origin-specific expression pattern of autosomal imprinted genes is maintained in various types of embryos. However, Xist imprinting for transcriptional silencing of maternal Xist was erased in cloned or parthenogenetic but not fertilized embryos. Here, we dissect the molecular mechanism underlying the variable nature of Xist imprinting. We show that in fertilized embryos, chromatin condensation states are essential maternal Xist repression in early preimplantation phases, whereas at late preimplantation stages, pluripotency factor Oct4 serves as a chromatin opener and the maintenance of Xist silencing depends on Rnf12 expression dosage. Although the Oct4 mediated chromatin decondensation also occurs in parthenogetic embryos, Rnf12 overdose causes maternal Xist derepression at late preimplantation phases. Thus these findings reveal that the chromatin regulation by pluripotency factor and Xist activator dose define Xist imprinting state.
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Affiliation(s)
- Atsushi Fukuda
- Center for Regenerative Medicine, National Research Institute for Child Health and Development, Okura, Setagaya, Tokyo, Japan
| | - Atsushi Mitani
- Center for Regenerative Medicine, National Research Institute for Child Health and Development, Okura, Setagaya, Tokyo, Japan
- Department of Molecular Genetics, Kitasato University Graduate School of Medical Sciences, Kitasato, Minami, Sagamihara, Kanagawa, Japan
| | - Toshiyuki Miyashita
- Department of Molecular Genetics, Kitasato University Graduate School of Medical Sciences, Kitasato, Minami, Sagamihara, Kanagawa, Japan
| | - Takashi Sado
- Department of Advanced Bioscience, Graduate School of Agriculture, Kindai University, Nakamachi, Nara, Japan
| | - Akihiro Umezawa
- Center for Regenerative Medicine, National Research Institute for Child Health and Development, Okura, Setagaya, Tokyo, Japan
| | - Hidenori Akutsu
- Center for Regenerative Medicine, National Research Institute for Child Health and Development, Okura, Setagaya, Tokyo, Japan
- Department of Stem Cell Research, Fukushima Medical University, Hikarigaoka, Fukushima City, Fukushima, Japan
- * E-mail:
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49
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Yang L, Kirby JE, Sunwoo H, Lee JT. Female mice lacking Xist RNA show partial dosage compensation and survive to term. Genes Dev 2016; 30:1747-60. [PMID: 27542829 PMCID: PMC5002979 DOI: 10.1101/gad.281162.116] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2016] [Accepted: 07/22/2016] [Indexed: 11/25/2022]
Abstract
X-chromosome inactivation (XCI) compensates for differences in X-chromosome number between male and female mammals. XCI is orchestrated by Xist RNA, whose expression in early development leads to transcriptional silencing of one X chromosome in the female. Knockout studies have established a requirement for Xist with inviability of female embryos that inherit an Xist deletion from the father. Here, we report that female mice lacking Xist RNA can, surprisingly, develop and survive to term. Xist-null females are born at lower frequency and are smaller at birth, but organogenesis is mostly normal. Transcriptomic analysis indicates significant overexpression of hundreds of X-linked genes across multiple tissues. Therefore, Xist-null mice can develop to term in spite of a deficiency of dosage compensation. However, the degree of X-autosomal dosage imbalance was less than anticipated (1.14-fold to 1.36-fold). Thus, partial dosage compensation can be achieved without Xist, supporting the idea of inherent genome balance. Nevertheless, to date, none of the mutant mice has survived beyond weaning stage. Sudden death is associated with failure of postnatal organ maturation. Our data suggest Xist-independent mechanisms of dosage compensation and demonstrate that small deviations from X-autosomal balance can have profound effects on overall fitness.
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Affiliation(s)
- Lin Yang
- Howard Hughes Medical Institute, Massachusetts General Hospital, Boston, Massachusetts 02114, USA; Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts 02114, USA; Department of Genetics, Harvard Medical School, Boston, Massachusetts 02114, USA
| | - James E Kirby
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02114, USA
| | - Hongjae Sunwoo
- Howard Hughes Medical Institute, Massachusetts General Hospital, Boston, Massachusetts 02114, USA; Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts 02114, USA; Department of Genetics, Harvard Medical School, Boston, Massachusetts 02114, USA
| | - Jeannie T Lee
- Howard Hughes Medical Institute, Massachusetts General Hospital, Boston, Massachusetts 02114, USA; Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts 02114, USA; Department of Genetics, Harvard Medical School, Boston, Massachusetts 02114, USA
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50
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Casanova M, Liyakat Ali TM, Rougeulle C. Enlightening the contribution of the dark matter to the X chromosome inactivation process in mammals. Semin Cell Dev Biol 2016; 56:48-57. [PMID: 27174438 DOI: 10.1016/j.semcdb.2016.05.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Revised: 05/04/2016] [Accepted: 05/04/2016] [Indexed: 02/07/2023]
Abstract
X-chromosome inactivation (XCI) in mammals represents an exceptional example of transcriptional co-regulation occurring at the level of an entire chromosome. XCI is considered as a means to compensate for gene dosage imbalance between sexes, yet the largest part of the chromosome is composed of repeated elements of different nature and origins. Here we consider XCI from a repeat point of view, interrogating the mechanisms for inactivating X chromosome-derived repeated sequences and discussing the contribution of repetitive elements to the silencing process itself and to its evolution.
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Affiliation(s)
- Miguel Casanova
- Sorbonne Paris Cité, Epigenetics and Cell Fate, UMR 7216 CNRS, Université Paris Diderot, Paris, France
| | | | - Claire Rougeulle
- Sorbonne Paris Cité, Epigenetics and Cell Fate, UMR 7216 CNRS, Université Paris Diderot, Paris, France.
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