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Shin J, Wallingford MC, Gallant J, Marcho C, Jiao B, Byron M, Bossenz M, Lawrence JB, Jones SN, Mager J, Bach I. RLIM is dispensable for X-chromosome inactivation in the mouse embryonic epiblast. Nature 2014; 511:86-9. [PMID: 24870238 PMCID: PMC4105192 DOI: 10.1038/nature13286] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2013] [Accepted: 03/26/2014] [Indexed: 01/12/2023]
Abstract
In female mice, two forms of X-chromosome inactivation (XCI) ensure the selective silencing of female sex chromosomes during mouse embryogenesis. Beginning at the four-cell stage, imprinted XCI (iXCI) exclusively silences the paternal X chromosome. Later, around implantation, epiblast cells of the inner cell mass that give rise to the embryo reactivate the paternal X chromosome and undergo a random form of XCI (rXCI). Xist, a long non-coding RNA crucial for both forms of XCI, is activated by the ubiquitin ligase RLIM (also known as Rnf12). Although RLIM is required for triggering iXCI in mice, its importance for rXCI has been controversial. Here we show that RLIM levels are downregulated in embryonic cells undergoing rXCI. Using mouse genetics we demonstrate that female cells lacking RLIM from pre-implantation stages onwards show hallmarks of XCI, including Xist clouds and H3K27me3 foci, and have full embryogenic potential. These results provide evidence that RLIM is dispensable for rXCI, indicating that in mice an RLIM-independent mechanism activates Xist in the embryo proper.
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Affiliation(s)
- JongDae Shin
- Program in Gene Function and Expression, University of Massachusetts Medical School (UMMS), Worcester, Massachusetts 01605, USA
| | - Mary C Wallingford
- Veterinary & Animal Sciences, University of Massachusetts Amherst, Amherst, Massachusetts 01003, USA
| | - Judith Gallant
- Department of Cell and Developmental Biology, UMMS, Worcester, Massachusetts 01605, USA
| | - Chelsea Marcho
- Veterinary & Animal Sciences, University of Massachusetts Amherst, Amherst, Massachusetts 01003, USA
| | - Baowei Jiao
- 1] Program in Gene Function and Expression, University of Massachusetts Medical School (UMMS), Worcester, Massachusetts 01605, USA [2] Kunming Institute of Zoology, Chinese Academy of Science, Kunming 650223, China
| | - Meg Byron
- Department of Cell and Developmental Biology, UMMS, Worcester, Massachusetts 01605, USA
| | - Michael Bossenz
- Ortenau Klinikum Lahr-Ettenheim, Institut für Pathologie, 77933 Lahr, Germany
| | - Jeanne B Lawrence
- Department of Cell and Developmental Biology, UMMS, Worcester, Massachusetts 01605, USA
| | - Stephen N Jones
- Department of Cell and Developmental Biology, UMMS, Worcester, Massachusetts 01605, USA
| | - Jesse Mager
- Veterinary & Animal Sciences, University of Massachusetts Amherst, Amherst, Massachusetts 01003, USA
| | - Ingolf Bach
- 1] Program in Gene Function and Expression, University of Massachusetts Medical School (UMMS), Worcester, Massachusetts 01605, USA [2] Program in Molecular Medicine, UMMS, Worcester, Massachusetts 01605, USA
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52
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Eckersley-Maslin MA, Spector DL. Random monoallelic expression: regulating gene expression one allele at a time. Trends Genet 2014; 30:237-44. [PMID: 24780084 DOI: 10.1016/j.tig.2014.03.003] [Citation(s) in RCA: 74] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2014] [Revised: 03/24/2014] [Accepted: 03/25/2014] [Indexed: 10/25/2022]
Abstract
Monoallelic gene expression is a remarkable process in which transcription occurs from only one of two homologous alleles in a diploid cell. Interestingly, between 0.5% and 15% of autosomal genes exhibit random monoallelic gene expression, in which different cells express only one allele independently of the underlying genomic sequence, in a cell type-specific manner. Recently, genome-wide studies have increased our understanding of the cell type-specific incidence of random monoallelic gene expression, and how the imbalance in allelic expression is distinguished within the cell and potentially maintained across cell generations. Monoallelic gene expression is likely generated through stochastic independent regulation of the two alleles upon differentiation, and has varied implications for the cell and organism, in particular with respect to disease.
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Affiliation(s)
- Mélanie A Eckersley-Maslin
- Watson School of Biological Sciences, Cold Spring Harbor Laboratory, One Bungtown Road, Cold Spring Harbor, NY 11724, USA
| | - David L Spector
- Watson School of Biological Sciences, Cold Spring Harbor Laboratory, One Bungtown Road, Cold Spring Harbor, NY 11724, USA.
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53
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Abstract
While large portions of the mammalian genome are known to replicate sequentially in a distinct, tissue-specific order, recent studies suggest that the inactive X chromosome is duplicated rapidly via random, synchronous DNA synthesis at numerous adjacent regions. The rapid duplication of the inactive X chromosome was observed in high-resolution studies visualizing DNA replication patterns in the nucleus, and by allele-specific DNA sequencing studies measuring the extent of DNA synthesis. These studies conclude that inactive X chromosomes complete replication earlier than previously thought and suggest that the strict order of DNA replication detected in the majority of genomic regions is not preserved in non-transcribed, "silent" chromatin. These observations alter current concepts about the regulation of DNA replication in non-transcribed portions of the genome in general and in the inactive X-chromosome in particular.
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Affiliation(s)
- Mirit I Aladjem
- Developmental Therapeutic Branch, Center for Cancer Research, National Cancer Institute, Bethesda, MD, USA
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54
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Pessia E, Engelstädter J, Marais GAB. The evolution of X chromosome inactivation in mammals: the demise of Ohno's hypothesis? Cell Mol Life Sci 2014; 71:1383-94. [PMID: 24173285 PMCID: PMC11113734 DOI: 10.1007/s00018-013-1499-6] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2013] [Revised: 10/11/2013] [Accepted: 10/14/2013] [Indexed: 12/24/2022]
Abstract
Ohno's hypothesis states that dosage compensation in mammals evolved in two steps: a twofold hyperactivation of the X chromosome in both sexes to compensate for gene losses on the Y chromosome, and silencing of one X (X-chromosome inactivation, XCI) in females to restore optimal dosage. Recent tests of this hypothesis have returned contradictory results. In this review, we explain this ongoing controversy and argue that a novel view on dosage compensation evolution in mammals is starting to emerge. Ohno's hypothesis may be true for a few, dosage-sensitive genes only. If so few genes are compensated, then why has XCI evolved as a chromosome-wide mechanism? This and several other questions raised by the new data in mammals are discussed, and future research directions are proposed.
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Affiliation(s)
- Eugénie Pessia
- Laboratoire de Biométrie et Biologie Évolutive, Centre National de la Recherche Scientifique, Université Lyon 1, Bat. Gregor Mendel, 16 rue Raphaël Dubois, 69622, Villeurbanne Cedex, France,
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55
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Abramowitz LK, Olivier-Van Stichelen S, Hanover JA. Chromosome imbalance as a driver of sex disparity in disease. J Genomics 2014; 2:77-88. [PMID: 25031659 PMCID: PMC4091450 DOI: 10.7150/jgen.8123] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
It has long been recognized that men and women exhibit different risks for diverse disorders ranging from metabolic to autoimmune diseases. However, the underlying causes of these disparities remain obscure. Analysis of patients with chromosomal abnormalities, including Turner syndrome (45X) and Klinefelter syndrome (47XXY), has highlighted the importance of X-linked gene dosage as a contributing factor for disease susceptibility. Escape from X-inactivation and X-linked imprinting can result in transcriptional differences between normal men and women as well as in patients with sex chromosome abnormalities. Animal models support a role for X-linked gene dosage in disease with O-linked N-acetylglucosamine transferase (OGT) emerging as a prime candidate for a pleiotropic effector. OGT encodes a highly regulated nutrient-sensing epigenetic modifier with established links to immunity, metabolism and development.
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Affiliation(s)
- Lara K Abramowitz
- Laboratory of Cell and Molecular Biology, NIDDK, National Institutes of Health, Bethesda, MD 20892-0851, USA
| | | | - John A Hanover
- Laboratory of Cell and Molecular Biology, NIDDK, National Institutes of Health, Bethesda, MD 20892-0851, USA
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56
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Eckersley-Maslin MA, Thybert D, Bergmann JH, Marioni JC, Flicek P, Spector DL. Random monoallelic gene expression increases upon embryonic stem cell differentiation. Dev Cell 2014; 28:351-65. [PMID: 24576421 PMCID: PMC3955261 DOI: 10.1016/j.devcel.2014.01.017] [Citation(s) in RCA: 92] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2013] [Revised: 12/21/2013] [Accepted: 01/21/2014] [Indexed: 11/23/2022]
Abstract
Random autosomal monoallelic gene expression refers to the transcription of a gene from one of two homologous alleles. We assessed the dynamics of monoallelic expression during development through an allele-specific RNA-sequencing screen in clonal populations of hybrid mouse embryonic stem cells (ESCs) and neural progenitor cells (NPCs). We identified 67 and 376 inheritable autosomal random monoallelically expressed genes in ESCs and NPCs, respectively, a 5.6-fold increase upon differentiation. Although DNA methylation and nuclear positioning did not distinguish the active and inactive alleles, specific histone modifications were differentially enriched between the two alleles. Interestingly, expression levels of 8% of the monoallelically expressed genes remained similar between monoallelic and biallelic clones. These results support a model in which random monoallelic expression occurs stochastically during differentiation and, for some genes, is compensated for by the cell to maintain the required transcriptional output of these genes.
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Affiliation(s)
- Mélanie A Eckersley-Maslin
- Cold Spring Harbor Laboratory, One Bungtown Road, Cold Spring Harbor, NY 11724, USA; Watson School of Biological Sciences, Cold Spring Harbor Laboratory, One Bungtown Road, Cold Spring Harbor, NY 11724, USA
| | - David Thybert
- European Molecular Biology Laboratory, European Bioinformatics Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge CB10 1SD, UK
| | - Jan H Bergmann
- Cold Spring Harbor Laboratory, One Bungtown Road, Cold Spring Harbor, NY 11724, USA
| | - John C Marioni
- European Molecular Biology Laboratory, European Bioinformatics Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge CB10 1SD, UK
| | - Paul Flicek
- European Molecular Biology Laboratory, European Bioinformatics Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge CB10 1SD, UK
| | - David L Spector
- Cold Spring Harbor Laboratory, One Bungtown Road, Cold Spring Harbor, NY 11724, USA; Watson School of Biological Sciences, Cold Spring Harbor Laboratory, One Bungtown Road, Cold Spring Harbor, NY 11724, USA.
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57
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Schulz EG, Meisig J, Nakamura T, Okamoto I, Sieber A, Picard C, Borensztein M, Saitou M, Blüthgen N, Heard E. The two active X chromosomes in female ESCs block exit from the pluripotent state by modulating the ESC signaling network. Cell Stem Cell 2014; 14:203-16. [PMID: 24506884 DOI: 10.1016/j.stem.2013.11.022] [Citation(s) in RCA: 117] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2013] [Revised: 10/18/2013] [Accepted: 11/26/2013] [Indexed: 01/18/2023]
Abstract
During early development of female mouse embryos, both X chromosomes are transiently active. X gene dosage is then equalized between the sexes through the process of X chromosome inactivation (XCI). Whether the double dose of X-linked genes in females compared with males leads to sex-specific developmental differences has remained unclear. Using embryonic stem cells with distinct sex chromosome compositions as a model system, we show that two X chromosomes stabilize the naive pluripotent state by inhibiting MAPK and Gsk3 signaling and stimulating the Akt pathway. Since MAPK signaling is required to exit the pluripotent state, differentiation is paused in female cells as long as both X chromosomes are active. By preventing XCI or triggering it precociously, we demonstrate that this differentiation block is released once XX cells have undergone X inactivation. We propose that double X dosage interferes with differentiation, thus ensuring a tight coupling between X chromosome dosage compensation and development.
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Affiliation(s)
- Edda G Schulz
- Mammalian Developmental Epigenetics Group, Institut Curie, CNRS UMR 3215, INSERM U934, Paris 75248, France.
| | - Johannes Meisig
- Institute of Pathology, Charité-Universitätsmedizin, 10117 Berlin, Germany; Integrative Research Institute for the Life Sciences and Institute for Theoretical Biology, Humboldt Universität, 10115 Berlin, Germany
| | - Tomonori Nakamura
- Department of Anatomy and Cell Biology, Graduate School of Medicine, Kyoto University, Yoshida-Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan; JST, ERATO, Yoshida-Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan
| | - Ikuhiro Okamoto
- Department of Anatomy and Cell Biology, Graduate School of Medicine, Kyoto University, Yoshida-Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan; JST, ERATO, Yoshida-Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan
| | - Anja Sieber
- Institute of Pathology, Charité-Universitätsmedizin, 10117 Berlin, Germany; Integrative Research Institute for the Life Sciences and Institute for Theoretical Biology, Humboldt Universität, 10115 Berlin, Germany
| | - Christel Picard
- Mammalian Developmental Epigenetics Group, Institut Curie, CNRS UMR 3215, INSERM U934, Paris 75248, France
| | - Maud Borensztein
- Mammalian Developmental Epigenetics Group, Institut Curie, CNRS UMR 3215, INSERM U934, Paris 75248, France
| | - Mitinori Saitou
- Department of Anatomy and Cell Biology, Graduate School of Medicine, Kyoto University, Yoshida-Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan; JST, ERATO, Yoshida-Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan; Center for iPS Cell Research and Application, Kyoto University, 53 Kawahara-cho, Shogoin Yoshida, Sakyo-ku, Kyoto 606-8507, Japan; Institute for Integrated Cell-Material Sciences, Kyoto University, Yoshida-Ushinomiya-cho, Sakyo-ku, Kyoto 606-8501, Japan
| | - Nils Blüthgen
- Institute of Pathology, Charité-Universitätsmedizin, 10117 Berlin, Germany; Integrative Research Institute for the Life Sciences and Institute for Theoretical Biology, Humboldt Universität, 10115 Berlin, Germany
| | - Edith Heard
- Mammalian Developmental Epigenetics Group, Institut Curie, CNRS UMR 3215, INSERM U934, Paris 75248, France.
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58
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Ferrari F, Alekseyenko AA, Park PJ, Kuroda MI. Transcriptional control of a whole chromosome: emerging models for dosage compensation. Nat Struct Mol Biol 2014; 21:118-25. [PMID: 24500429 PMCID: PMC4342042 DOI: 10.1038/nsmb.2763] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2013] [Accepted: 12/16/2013] [Indexed: 12/24/2022]
Abstract
Males and females of many animal species differ in their sex-chromosome karyotype, and this creates imbalances between X-chromosome and autosomal gene products that require compensation. Although distinct molecular mechanisms have evolved in three highly studied systems, they all achieve coordinate regulation of an entire chromosome by differential RNA-polymerase occupancy at X-linked genes. High-throughput genome-wide methods have been pivotal in driving the latest progress in the field. Here we review the emerging models for dosage compensation in mammals, flies and nematodes, with a focus on mechanisms affecting RNA polymerase II activity on the X chromosome.
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Affiliation(s)
- Francesco Ferrari
- Center for Biomedical Informatics, Harvard Medical School, Boston, Massachusetts, USA
| | - Artyom A Alekseyenko
- 1] Department of Medicine, Division of Genetics, Brigham and Women's Hospital, Boston, Massachusetts, USA. [2] Department of Genetics, Harvard Medical School, Boston, Massachusetts, USA
| | - Peter J Park
- 1] Center for Biomedical Informatics, Harvard Medical School, Boston, Massachusetts, USA. [2] Department of Medicine, Division of Genetics, Brigham and Women's Hospital, Boston, Massachusetts, USA
| | - Mitzi I Kuroda
- 1] Department of Medicine, Division of Genetics, Brigham and Women's Hospital, Boston, Massachusetts, USA. [2] Department of Genetics, Harvard Medical School, Boston, Massachusetts, USA
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59
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Chery J, Larschan E. X-marks the spot: X-chromosome identification during dosage compensation. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2014; 1839:234-40. [PMID: 24406325 DOI: 10.1016/j.bbagrm.2013.12.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2013] [Revised: 12/29/2013] [Accepted: 12/30/2013] [Indexed: 12/11/2022]
Abstract
Dosage compensation is the essential process that equalizes the dosage of X-linked genes between the sexes in heterogametic species. Because all of the genes along the length of a single chromosome are co-regulated, dosage compensation serves as a model system for understanding how domains of coordinate gene regulation are established. Dosage compensation has been best studied in mammals, flies and worms. Although dosage compensation systems are seemingly diverse across species, there are key shared principles of nucleation and spreading that are critical for accurate targeting of the dosage compensation complex to the X-chromosome(s). We will highlight the mechanisms by which long non-coding RNAs function together with DNA sequence elements to tether dosage compensation complexes to the X-chromosome. This article is part of a Special Issue entitled: Chromatin and epigenetic regulation of animal development.
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Affiliation(s)
- Jessica Chery
- Department of Molecular Biology, Cellular Biology, and Biochemistry, Brown University, 185 Meeting Street, Providence, RI 02912, USA
| | - Erica Larschan
- Department of Molecular Biology, Cellular Biology, and Biochemistry, Brown University, 185 Meeting Street, Providence, RI 02912, USA.
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60
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Leeb M, Wutz A. Haploid genomes illustrate epigenetic constraints and gene dosage effects in mammals. Epigenetics Chromatin 2013; 6:41. [PMID: 24305551 PMCID: PMC4175507 DOI: 10.1186/1756-8935-6-41] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2013] [Accepted: 11/18/2013] [Indexed: 11/10/2022] Open
Abstract
Sequencing projects have revealed the information of many animal genomes and thereby enabled the exploration of genome evolution. Insights into how genomes have been repeatedly modified provide a basis for understanding evolutionary innovation and the ever increasing complexity of animal developmental programs. Animal genomes are diploid in most cases, suggesting that redundant information in two copies of the genome increases evolutionary fitness. Genomes are well adapted to a diploid state. Changes of ploidy can be accommodated early in development but they rarely permit successful development into adulthood. In mammals, epigenetic mechanisms including imprinting and X inactivation restrict haploid development. These restrictions are relaxed in an early phase of development suggesting that dosage regulation appears less critical. Here we review the recent literature on haploid genomes and dosage effects and try to embed recent findings in an evolutionary perspective.
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Affiliation(s)
- Martin Leeb
- Wellcome Trust-Medical Research Council Stem Cell Institute, University of Cambridge, Tennis Court Road, Cambridge CB2 1QR, UK.
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