1
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Bansal P, Banda EC, Glatt-Deeley HR, Stoddard CE, Linsley JW, Arora N, Deleschaux C, Ahern DT, Kondaveeti Y, Massey RE, Nicouleau M, Wang S, Sabariego-Navarro M, Dierssen M, Finkbeiner S, Pinter SF. A dynamic in vitro model of Down syndrome neurogenesis with trisomy 21 gene dosage correction. SCIENCE ADVANCES 2024; 10:eadj0385. [PMID: 38848354 PMCID: PMC11160455 DOI: 10.1126/sciadv.adj0385] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2023] [Accepted: 05/03/2024] [Indexed: 06/09/2024]
Abstract
Excess gene dosage from chromosome 21 (chr21) causes Down syndrome (DS), spanning developmental and acute phenotypes in terminal cell types. Which phenotypes remain amenable to intervention after development is unknown. To address this question in a model of DS neurogenesis, we derived trisomy 21 (T21) human induced pluripotent stem cells (iPSCs) alongside, otherwise, isogenic euploid controls from mosaic DS fibroblasts and equipped one chr21 copy with an inducible XIST transgene. Monoallelic chr21 silencing by XIST is near-complete and irreversible in iPSCs. Differential expression reveals that T21 neural lineages and iPSCs share suppressed translation and mitochondrial pathways and activate cellular stress responses. When XIST is induced before the neural progenitor stage, T21 dosage correction suppresses a pronounced skew toward astrogenesis in neural differentiation. Because our transgene remains inducible in postmitotic T21 neurons and astrocytes, we demonstrate that XIST efficiently represses genes even after terminal differentiation, which will empower exploration of cell type-specific T21 phenotypes that remain responsive to chr21 dosage.
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Affiliation(s)
- Prakhar Bansal
- Graduate Program in Genetics and Developmental Biology, UCONN Health, University of Connecticut, Farmington, CT, USA
- Department of Genetics and Genome Sciences, UCONN Health, University of Connecticut, Farmington, CT, USA
| | - Erin C. Banda
- Department of Genetics and Genome Sciences, UCONN Health, University of Connecticut, Farmington, CT, USA
| | - Heather R. Glatt-Deeley
- Department of Genetics and Genome Sciences, UCONN Health, University of Connecticut, Farmington, CT, USA
| | - Christopher E. Stoddard
- Cell and Genome Engineering Core, UCONN Health, University of Connecticut, Farmington, CT, USA
| | - Jeremy W. Linsley
- Center for Systems and Therapeutics, Gladstone Institutes, San Francisco, CA, USA
- Taube/Koret Center for Neurodegenerative Disease, Gladstone Institutes, San Francisco, CA, USA
| | - Neha Arora
- Center for Systems and Therapeutics, Gladstone Institutes, San Francisco, CA, USA
| | - Cécile Deleschaux
- Department of Genetics and Genome Sciences, UCONN Health, University of Connecticut, Farmington, CT, USA
| | - Darcy T. Ahern
- Graduate Program in Genetics and Developmental Biology, UCONN Health, University of Connecticut, Farmington, CT, USA
- Department of Genetics and Genome Sciences, UCONN Health, University of Connecticut, Farmington, CT, USA
| | - Yuvabharath Kondaveeti
- Department of Genetics and Genome Sciences, UCONN Health, University of Connecticut, Farmington, CT, USA
| | - Rachael E. Massey
- Graduate Program in Genetics and Developmental Biology, UCONN Health, University of Connecticut, Farmington, CT, USA
- Department of Genetics and Genome Sciences, UCONN Health, University of Connecticut, Farmington, CT, USA
- Institute for Systems Genomics, University of Connecticut, Farmington, CT, USA
| | - Michael Nicouleau
- Department of Genetics and Genome Sciences, UCONN Health, University of Connecticut, Farmington, CT, USA
| | - Shijie Wang
- Center for Systems and Therapeutics, Gladstone Institutes, San Francisco, CA, USA
| | - Miguel Sabariego-Navarro
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Barcelona, Spain
| | - Mara Dierssen
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Barcelona, Spain
- Universitat Pompeu Fabra (UPF), Barcelona, Spain
- Human Pharmacology and Clinical Neurosciences Research Group, Neurosciences Research Program, Hospital Del Mar Medical Research Institute (IMIM), Barcelona, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, Spain
| | - Steven Finkbeiner
- Center for Systems and Therapeutics, Gladstone Institutes, San Francisco, CA, USA
- Taube/Koret Center for Neurodegenerative Disease, Gladstone Institutes, San Francisco, CA, USA
- Departments of Neurology and Physiology, University of California San Francisco, San Francisco, CA, USA
- Neuroscience and Biomedical Sciences Graduate Programs, University of California San Francisco, San Francisco, CA, USA
| | - Stefan F. Pinter
- Graduate Program in Genetics and Developmental Biology, UCONN Health, University of Connecticut, Farmington, CT, USA
- Department of Genetics and Genome Sciences, UCONN Health, University of Connecticut, Farmington, CT, USA
- Institute for Systems Genomics, University of Connecticut, Farmington, CT, USA
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2
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Lovell CD, Jiwrajka N, Amerman HK, Cancro MP, Anguera MC. Xist Deletion in B Cells Results in Systemic Lupus Erythematosus Phenotypes. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.15.594175. [PMID: 38798403 PMCID: PMC11118349 DOI: 10.1101/2024.05.15.594175] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2024]
Abstract
Systemic lupus erythematosus (SLE) is an autoimmune disease preferentially observed in females. X-linked gene expression in XX females is normalized to that of XY males by X-Chromosome Inactivation (XCI). However, B cells from female SLE patients and mouse models of SLE exhibit mislocalization of Xist RNA, a critical regulator of XCI, and aberrant expression of X-linked genes, suggesting that impairment of XCI may contribute to disease. Here, we find that a subset of female mice harboring a conditional deletion of Xis t in B cells ("Xist cKO") spontaneously develop SLE phenotypes, including expanded activated B cell subsets, disease-specific autoantibodies, and glomerulonephritis. Moreover, pristane-induced SLE-like disease is more severe in Xist cKO mice. Activated B cells from Xist cKO mice with SLE phenotypes have increased expression of proinflammatory X-linked genes implicated in SLE. Together, this work indicates that impaired XCI maintenance in B cells directly contributes to the female-bias of SLE.
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3
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Hauth A, Panten J, Kneuss E, Picard C, Servant N, Rall I, Pérez-Rico YA, Clerquin L, Servaas N, Villacorta L, Jung F, Luong C, Chang HY, Zaugg JB, Stegle O, Odom DT, Loda A, Heard E. Escape from X inactivation is directly modulated by levels of Xist non-coding RNA. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.22.581559. [PMID: 38559194 PMCID: PMC10979913 DOI: 10.1101/2024.02.22.581559] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
In placental females, one copy of the two X chromosomes is largely silenced during a narrow developmental time window, in a process mediated by the non-coding RNA Xist1. Here, we demonstrate that Xist can initiate X-chromosome inactivation (XCI) well beyond early embryogenesis. By modifying its endogenous level, we show that Xist has the capacity to actively silence genes that escape XCI both in neuronal progenitor cells (NPCs) and in vivo, in mouse embryos. We also show that Xist plays a direct role in eliminating TAD-like structures associated with clusters of escapee genes on the inactive X chromosome, and that this is dependent on Xist's XCI initiation partner, SPEN2. We further demonstrate that Xist's function in suppressing gene expression of escapees and topological domain formation is reversible for up to seven days post-induction, but that sustained Xist up-regulation leads to progressively irreversible silencing and CpG island DNA methylation of facultative escapees. Thus, the distinctive transcriptional and regulatory topologies of the silenced X chromosome is actively, directly - and reversibly - controlled by Xist RNA throughout life.
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Affiliation(s)
- Antonia Hauth
- European Molecular Biology Laboratory, Directors' Research, 69117 Heidelberg, Germany
- Collaboration for joint PhD degree between EMBL and Heidelberg University, Germany
| | - Jasper Panten
- Division of Regulatory Genomics and Cancer Evolution, German Cancer Research Centre (DKFZ), 69120, Heidelberg, Germany
- Division of Computational Genomics and Systems Genetics, German Cancer Research Centre (DKFZ), 69120, Heidelberg, Germany
- Faculty of Biosciences, Heidelberg University, 69117, Heidelberg, Germany
| | - Emma Kneuss
- European Molecular Biology Laboratory, Directors' Research, 69117 Heidelberg, Germany
| | - Christel Picard
- European Molecular Biology Laboratory, Directors' Research, 69117 Heidelberg, Germany
- Present address: Institute of Molecular Genetics of Montpellier University of Montpellier, CNRS, 34090 Montpellier, France
| | - Nicolas Servant
- Bioinformatics and Computational Systems Biology of Cancer, INSERM U900, Paris 75005, France
| | - Isabell Rall
- European Molecular Biology Laboratory, Directors' Research, 69117 Heidelberg, Germany
- Present address: Institute of Human Biology (IHB), Roche Innovation Center Basel, 4070 Basel, Switzerland
| | - Yuvia A Pérez-Rico
- European Molecular Biology Laboratory, Directors' Research, 69117 Heidelberg, Germany
| | - Lena Clerquin
- European Molecular Biology Laboratory, Directors' Research, 69117 Heidelberg, Germany
| | - Nila Servaas
- European Molecular Biology Laboratory, Structural and Computational Biology Unit, 69117 Heidelberg, Germany
| | - Laura Villacorta
- European Molecular Biology Laboratory, Genomics Core Facility, 69117 Heidelberg, Germany
| | - Ferris Jung
- European Molecular Biology Laboratory, Genomics Core Facility, 69117 Heidelberg, Germany
| | - Christy Luong
- Center for Personal Dynamic Regulomes, Stanford University, Stanford, CA 94305, USA
| | - Howard Y Chang
- Center for Personal Dynamic Regulomes, Stanford University, Stanford, CA 94305, USA
- Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - Judith B Zaugg
- European Molecular Biology Laboratory, Structural and Computational Biology Unit, 69117 Heidelberg, Germany
- Molecular Medicine Partnership Unit, EMBL-University of Heidelberg, Heidelberg, Germany
| | - Oliver Stegle
- European Molecular Biology Laboratory, Genome Biology Unit, 69117 Heidelberg, Germany
- Division of Computational Genomics and Systems Genetics, German Cancer Research Centre (DKFZ), 69120, Heidelberg, Germany
| | - Duncan T Odom
- Division of Regulatory Genomics and Cancer Evolution, German Cancer Research Centre (DKFZ), 69120, Heidelberg, Germany
- Faculty of Biosciences, Heidelberg University, 69117, Heidelberg, Germany
- Cancer Research UK Cambridge Institute, University of Cambridge, Cambridge, UK
| | - Agnese Loda
- European Molecular Biology Laboratory, Directors' Research, 69117 Heidelberg, Germany
| | - Edith Heard
- European Molecular Biology Laboratory, Directors' Research, 69117 Heidelberg, Germany
- Collège de France, Paris 75005, France
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4
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Forsyth KS, Toothacre NE, Jiwrajka N, Driscoll AM, Shallberg LA, Cunningham-Rundles C, Barmettler S, Farmer J, Verbsky J, Routes J, Beiting DP, Romberg N, May MJ, Anguera MC. NF-κB Signaling is Required for X-Chromosome Inactivation Maintenance Following T cell Activation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.08.579505. [PMID: 38405871 PMCID: PMC10888971 DOI: 10.1101/2024.02.08.579505] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/27/2024]
Abstract
X Chromosome Inactivation (XCI) is a female-specific process which balances X-linked gene dosage between sexes. Unstimulated T cells lack cytological enrichment of Xist RNA and heterochromatic modifications on the inactive X chromosome (Xi), and these modifications become enriched at the Xi after cell stimulation. Here, we examined allele-specific gene expression and the epigenomic profiles of the Xi following T cell stimulation. We found that the Xi in unstimulated T cells is largely dosage compensated and is enriched with the repressive H3K27me3 modification, but not the H2AK119-ubiquitin (Ub) mark, even at promoters of XCI escape genes. Upon CD3/CD28-mediated T cell stimulation, the Xi accumulates H2AK119-Ub and H3K27me3 across the Xi. Next, we examined the T cell signaling pathways responsible for Xist RNA localization to the Xi and found that T cell receptor (TCR) engagement, specifically NF-κB signaling downstream of TCR, is required. Disruption of NF-κB signaling, using inhibitors or genetic deletions, in mice and patients with immunodeficiencies prevents Xist/XIST RNA accumulation at the Xi and alters expression of some X-linked genes. Our findings reveal a novel connection between NF-κB signaling pathways which impact XCI maintenance in female T cells.
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5
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Luchsinger-Morcelle SJ, Gribnau J, Mira-Bontenbal H. Orchestrating Asymmetric Expression: Mechanisms behind Xist Regulation. EPIGENOMES 2024; 8:6. [PMID: 38390897 PMCID: PMC10885031 DOI: 10.3390/epigenomes8010006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Revised: 01/19/2024] [Accepted: 01/22/2024] [Indexed: 02/24/2024] Open
Abstract
Compensation for the gene dosage disequilibrium between sex chromosomes in mammals is achieved in female cells by repressing one of its X chromosomes through a process called X chromosome inactivation (XCI), exemplifying the control of gene expression by epigenetic mechanisms. A critical player in this mechanism is Xist, a long, non-coding RNA upregulated from a single X chromosome during early embryonic development in female cells. Over the past few decades, many factors involved at different levels in the regulation of Xist have been discovered. In this review, we hierarchically describe and analyze the different layers of Xist regulation operating concurrently and intricately interacting with each other to achieve asymmetric and monoallelic upregulation of Xist in murine female cells. We categorize these into five different classes: DNA elements, transcription factors, other regulatory proteins, long non-coding RNAs, and the chromatin and topological landscape surrounding Xist.
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Affiliation(s)
| | - Joost Gribnau
- Department of Developmental Biology, Erasmus MC, University Medical Center, 3015 GD Rotterdam, The Netherlands
| | - Hegias Mira-Bontenbal
- Department of Developmental Biology, Erasmus MC, University Medical Center, 3015 GD Rotterdam, The Netherlands
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6
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Obuse C, Hirose T. Functional domains of nuclear long noncoding RNAs: Insights into gene regulation and intracellular architecture. Curr Opin Cell Biol 2023; 85:102250. [PMID: 37806294 DOI: 10.1016/j.ceb.2023.102250] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Revised: 08/12/2023] [Accepted: 09/07/2023] [Indexed: 10/10/2023]
Abstract
Recent functional research on long noncoding RNAs (lncRNAs) has revealed their significant regulatory roles in gene expression and intracellular architecture. Well-characterized examples of such lncRNAs include Xist and NEAT1_2, which play critical roles in heterochromatin formation of inactive X-chromosomes and paraspeckle assembly, in mammalian cells. Both lncRNAs possess modular domain structures with multiple functionally distinct domains that serve as platforms for specific RNA-binding proteins (RBPs), which dictate the function of each lncRNA. Some of these RBPs bind characteristic RNA structures, which can be targeted by small chemical compounds that modulate lncRNA function by perturbing the interaction of RBPs with the RNA structures. Therefore, RNA structures hidden in lncRNAs represent a novel and potent type of therapeutic target.
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Affiliation(s)
- Chikashi Obuse
- Graduate School of Science, Osaka University, Toyonaka 560-0043, Japan; Institute for Open and Transdisciplinary Research Initiatives (OTRI), Osaka University, Suita 565-0871, Japan
| | - Tetsuro Hirose
- Graduate School of Science, Osaka University, Toyonaka 560-0043, Japan; Graduate School of Frontier Biosciences, Osaka University, Suita 565-0871, Japan; Institute for Open and Transdisciplinary Research Initiatives (OTRI), Osaka University, Suita 565-0871, Japan.
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7
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Keniry A, Blewitt ME. Chromatin-mediated silencing on the inactive X chromosome. Development 2023; 150:dev201742. [PMID: 37991053 DOI: 10.1242/dev.201742] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2023]
Abstract
In mammals, the second X chromosome in females is silenced to enable dosage compensation between XX females and XY males. This essential process involves the formation of a dense chromatin state on the inactive X (Xi) chromosome. There is a wealth of information about the hallmarks of Xi chromatin and the contribution each makes to silencing, leaving the tantalising possibility of learning from this knowledge to potentially remove silencing to treat X-linked diseases in females. Here, we discuss the role of each chromatin feature in the establishment and maintenance of the silent state, which is of crucial relevance for such a goal.
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Affiliation(s)
- Andrew Keniry
- Epigenetics and Development Division, The Walter and Eliza Hall Institute for Medical Research, 1G Royal Parade, Parkville, VIC 3052, Australia
- The Department of Medical Biology, University of Melbourne, Parkville, VIC 3010, Australia
| | - Marnie E Blewitt
- Epigenetics and Development Division, The Walter and Eliza Hall Institute for Medical Research, 1G Royal Parade, Parkville, VIC 3052, Australia
- The Department of Medical Biology, University of Melbourne, Parkville, VIC 3010, Australia
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8
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Sierra I, Pyfrom S, Weiner A, Zhao G, Driscoll A, Yu X, Gregory BD, Vaughan AE, Anguera MC. Unusual X chromosome inactivation maintenance in female alveolar type 2 cells is correlated with increased numbers of X-linked escape genes and sex-biased gene expression. Stem Cell Reports 2023; 18:489-502. [PMID: 36638790 PMCID: PMC9968984 DOI: 10.1016/j.stemcr.2022.12.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Revised: 12/07/2022] [Accepted: 12/08/2022] [Indexed: 01/13/2023] Open
Abstract
Sex differences exist for many lung pathologies, including COVID-19 and pulmonary fibrosis, but the mechanistic basis for this remains unclear. Alveolar type 2 cells (AT2s), which play a key role in alveolar lung regeneration, express the X-linked Ace2 gene that has roles in lung repair and SARS-CoV-2 pathogenesis, suggesting that X chromosome inactivation (XCI) in AT2s might impact sex-biased lung pathology. Here we investigate XCI maintenance and sex-specific gene expression profiles using male and female AT2s. Remarkably, the inactive X chromosome (Xi) lacks robust canonical Xist RNA "clouds" and less enrichment of heterochromatic modifications in human and mouse AT2s. We demonstrate that about 68% of expressed X-linked genes in mouse AT2s, including Ace2, escape XCI. There are genome-wide expression differences between male and female AT2s, likely influencing both lung physiology and pathophysiologic responses. These studies support a renewed focus on AT2s as a potential contributor to sex-biased differences in lung disease.
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Affiliation(s)
- Isabel Sierra
- Department of Biomedical Sciences, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Sarah Pyfrom
- Department of Biomedical Sciences, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Aaron Weiner
- Department of Biomedical Sciences, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Gan Zhao
- Department of Biomedical Sciences, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Amanda Driscoll
- Department of Biomedical Sciences, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Xiang Yu
- Joint International Research Laboratory of Metabolic & Developmental Sciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Brian D Gregory
- Department of Biology, University of Pennsylvania, Philadelphia, PA, USA
| | - Andrew E Vaughan
- Department of Biomedical Sciences, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, USA; Institute for Regenerative Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Penn Lung Biology Institute, University of Pennsylvania, Philadelphia, PA 19104, USA.
| | - Montserrat C Anguera
- Department of Biomedical Sciences, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, USA; Institute for Regenerative Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
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9
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Grimm NB, Lee JT. Selective Xi reactivation and alternative methods to restore MECP2 function in Rett syndrome. Trends Genet 2022; 38:920-943. [PMID: 35248405 PMCID: PMC9915138 DOI: 10.1016/j.tig.2022.01.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 01/15/2022] [Accepted: 01/19/2022] [Indexed: 10/19/2022]
Abstract
The human X-chromosome harbors only 4% of our genome but carries over 20% of genes associated with intellectual disability. Given that they inherit only one X-chromosome, males are more frequently affected by X-linked neurodevelopmental genetic disorders than females. However, despite inheriting two X-chromosomes, females can also be affected because X-chromosome inactivation enables only one of two X-chromosomes to be expressed per cell. For Rett syndrome and similar X-linked disorders affecting females, disease-specific treatments have remained elusive. However, a cure may be found within their own cells because every sick cell carries a healthy copy of the affected gene on the inactive X (Xi). Therefore, selective Xi reactivation may be a viable approach that would address the root cause of various X-linked disorders. Here, we discuss Rett syndrome and compare current approaches in the pharmaceutical pipeline to restore MECP2 function. We then focus on Xi reactivation and review available methods, lessons learned, and future directions.
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Affiliation(s)
- Niklas-Benedikt Grimm
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA, USA; Department of Genetics, The Blavatnik Institute, Harvard Medical School, Boston, MA, USA; Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Barcelona, Spain; Universitat Pompeu Fabra (UPF), Barcelona, Spain
| | - Jeannie T Lee
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA, USA; Department of Genetics, The Blavatnik Institute, Harvard Medical School, Boston, MA, USA.
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10
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XIST loss impairs mammary stem cell differentiation and increases tumorigenicity through Mediator hyperactivation. Cell 2022; 185:2164-2183.e25. [PMID: 35597241 DOI: 10.1016/j.cell.2022.04.034] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Revised: 01/10/2022] [Accepted: 04/27/2022] [Indexed: 12/27/2022]
Abstract
X inactivation (XCI) is triggered by upregulation of XIST, which coats the chromosome in cis, promoting formation of a heterochromatic domain (Xi). XIST role beyond initiation of XCI is only beginning to be elucidated. Here, we demonstrate that XIST loss impairs differentiation of human mammary stem cells (MaSCs) and promotes emergence of highly tumorigenic and metastatic carcinomas. On the Xi, XIST deficiency triggers epigenetic changes and reactivation of genes overlapping Polycomb domains, including Mediator subunit MED14. MED14 overdosage results in increased Mediator levels and hyperactivation of the MaSC enhancer landscape and transcriptional program, making differentiation less favorable. We further demonstrate that loss of XIST and Xi transcriptional instability is common among human breast tumors of poor prognosis. We conclude that XIST is a gatekeeper of human mammary epithelium homeostasis, thus unveiling a paradigm in the control of somatic cell identity with potential consequences for our understanding of gender-specific malignancies.
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11
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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: 45] [Impact Index Per Article: 22.5] [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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12
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Matoba S, Kozuka C, Miura K, Inoue K, Kumon M, Hayashi R, Ohhata T, Ogura A, Inoue A. Noncanonical imprinting sustains embryonic development and restrains placental overgrowth. Genes Dev 2022; 36:483-494. [PMID: 35483741 PMCID: PMC9067403 DOI: 10.1101/gad.349390.122] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2022] [Accepted: 04/08/2022] [Indexed: 01/23/2023]
Abstract
In this study, Matoba et al. use a combinatorial maternal KO of Xist, a noncanonical imprinted gene whose LOI causes aberrant transient maternal X-chromosome inactivation (XCI) at preimplantation, and show that prevention of the transient maternal XCI greatly restores the development of Eed matKO embryos. Their findings provide evidence that Xist imprinting sustains embryonic development and that autosomal noncanonical imprinting restrains placental overgrowth. Genomic imprinting regulates parental origin-dependent monoallelic gene expression. It is mediated by either germline differential methylation of DNA (canonical imprinting) or oocyte-derived H3K27me3 (noncanonical imprinting) in mice. Depletion of Eed, an essential component of Polycomb repressive complex 2, results in genome-wide loss of H3K27me3 in oocytes, which causes loss of noncanonical imprinting (LOI) in embryos. Although Eed maternal KO (matKO) embryos show partial lethality after implantation, it is unknown whether LOI itself contributes to the developmental phenotypes of these embryos, which makes it unclear whether noncanonical imprinting is developmentally relevant. Here, by combinatorial matKO of Xist, a noncanonical imprinted gene whose LOI causes aberrant transient maternal X-chromosome inactivation (XCI) at preimplantation, we show that prevention of the transient maternal XCI greatly restores the development of Eed matKO embryos. Moreover, we found that the placentae of Eed matKO embryos are remarkably enlarged in a manner independent of Xist LOI. Heterozygous deletion screening of individual autosomal noncanonical imprinted genes suggests that LOI of the Sfmbt2 miRNA cluster chromosome 2 miRNA cluster (C2MC), solute carrier family 38 member 4 (Slc38a4), and Gm32885 contributes to the placental enlargement. Taken together, our study provides evidence that Xist imprinting sustains embryonic development and that autosomal noncanonical imprinting restrains placental overgrowth.
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Affiliation(s)
- Shogo Matoba
- Bioresource Engineering Division, RIKEN Bioresource Research Center, Tsukuba 305-0074, Japan.,Cooperative Division of Veterinary Sciences, Tokyo University of Agriculture and Technology, Fuchu 183-8509, Japan
| | - Chisayo Kozuka
- Young Chief Investigator (YCI) Laboratory for Metabolic Epigenetics, RIKEN Center for Integrative Medical Sciences, Yokohama 230-0045, Japan
| | - Kento Miura
- Bioresource Engineering Division, RIKEN Bioresource Research Center, Tsukuba 305-0074, Japan.,Department of Disease Model, Research Institute of Radiation Biology and Medicine, Hiroshima University, Hiroshima 734-8553, Japan
| | - Kimiko Inoue
- Bioresource Engineering Division, RIKEN Bioresource Research Center, Tsukuba 305-0074, Japan.,Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba 305-8572, Japan
| | - Mami Kumon
- Young Chief Investigator (YCI) Laboratory for Metabolic Epigenetics, RIKEN Center for Integrative Medical Sciences, Yokohama 230-0045, Japan
| | - Ryoya Hayashi
- Young Chief Investigator (YCI) Laboratory for Metabolic Epigenetics, RIKEN Center for Integrative Medical Sciences, Yokohama 230-0045, Japan.,Tokyo Metropolitan University, Hachioji 192-0397, Japan
| | - Tatsuya Ohhata
- Department of Molecular Biology, Hamamatsu University School of Medicine, Hamamatsu 431-3192, Japan
| | - Atsuo Ogura
- Bioresource Engineering Division, RIKEN Bioresource Research Center, Tsukuba 305-0074, Japan.,Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba 305-8572, Japan.,The Center for Disease Biology and Integrative Medicine, Faculty of Medicine, University of Tokyo, Tokyo 113-0033, Japan.,RIKEN Cluster for Pioneering Research, Wako 351-0198, Japan
| | - Azusa Inoue
- Young Chief Investigator (YCI) Laboratory for Metabolic Epigenetics, RIKEN Center for Integrative Medical Sciences, Yokohama 230-0045, Japan.,Tokyo Metropolitan University, Hachioji 192-0397, Japan
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13
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Creamer KM, Larsen EC, Lawrence JB. ZNF146/OZF and ZNF507 target LINE-1 sequences. G3 (BETHESDA, MD.) 2022; 12:jkac002. [PMID: 35100360 PMCID: PMC8896011 DOI: 10.1093/g3journal/jkac002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/03/2021] [Accepted: 12/03/2021] [Indexed: 06/14/2023]
Abstract
Repetitive sequences including transposable elements and transposon-derived fragments account for nearly half of the human genome. While transposition-competent transposable elements must be repressed to maintain genomic stability, mutated and fragmented transposable elements comprising the bulk of repetitive sequences can also contribute to regulation of host gene expression and broader genome organization. Here, we analyzed published ChIP-seq data sets to identify proteins broadly enriched on transposable elements in the human genome. We show 2 of the proteins identified, C2H2 zinc finger-containing proteins ZNF146 (also known as OZF) and ZNF507, are targeted to distinct sites within LINE-1 ORF2 at thousands of locations in the genome. ZNF146 binding sites are found at old and young LINE-1 elements. In contrast, ZNF507 preferentially binds at young LINE-1 sequences correlated to sequence changes in LINE-1 elements at ZNF507's binding site. To gain further insight into ZNF146 and ZNF507 function, we disrupt their expression in HEK293 cells using CRISPR/Cas9 and perform RNA sequencing, finding modest gene expression changes in cells where ZNF507 has been disrupted. We further identify a physical interaction between ZNF507 and PRMT5, suggesting ZNF507 may target arginine methylation activity to LINE-1 sequences.
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Affiliation(s)
- Kevin M Creamer
- Department of Neurology and Pediatrics, University of Massachusetts Medical School, Worcester, MA 01655, USA
| | - Eric C Larsen
- Department of Neurology and Pediatrics, University of Massachusetts Medical School, Worcester, MA 01655, USA
| | - Jeanne B Lawrence
- Department of Neurology and Pediatrics, University of Massachusetts Medical School, Worcester, MA 01655, USA
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14
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Mira-Bontenbal H, Tan B, Gontan C, Goossens S, Boers RG, Boers JB, Dupont C, van Royen ME, IJcken WFJ, French P, Bedalov A, Gribnau J. Genetic and epigenetic determinants of reactivation of Mecp2 and the inactive X chromosome in neural stem cells. Stem Cell Reports 2022; 17:693-706. [PMID: 35148843 PMCID: PMC9039756 DOI: 10.1016/j.stemcr.2022.01.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Revised: 01/10/2022] [Accepted: 01/10/2022] [Indexed: 01/17/2023] Open
Abstract
Rett syndrome may be treated by reactivating the silent copy of Mecp2 from the inactive X chromosome in female cells. Most studies that model Mecp2 reactivation have used mouse fibroblasts rather than neural cells, which would be critical for phenotypic reversal, and rely on fluorescent reporters that lack adequate sensitivity. Here, we present a mouse model based on a dual bioluminescent and fluorescent reporter to assess the level of reactivation of Mecp2 and the inactive X chromosome by treating neural stem cells with 5-azacytidine and Xist knockdown. We show that reactivation of Mecp2 and other X-linked genes correlates with CpG density, with distance from escapees, and, very strongly, with the presence of short interspersed nuclear elements. In addition, X-linked genes reactivated in neural stem cells overlap substantially with early reactivating genes by induced pluripotent stem cell reprogramming of fibroblasts or neuronal progenitors, indicating that X chromosome reactivation follows similar paths regardless of the technique or cell type used.
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Affiliation(s)
- H Mira-Bontenbal
- Oncode Institue, Department of Developmental Biology, Erasmus MC, Rotterdam, the Netherlands.
| | - B Tan
- Oncode Institue, Department of Developmental Biology, Erasmus MC, Rotterdam, the Netherlands
| | - C Gontan
- Oncode Institue, Department of Developmental Biology, Erasmus MC, Rotterdam, the Netherlands
| | - S Goossens
- Oncode Institue, Department of Developmental Biology, Erasmus MC, Rotterdam, the Netherlands
| | - R G Boers
- Oncode Institue, Department of Developmental Biology, Erasmus MC, Rotterdam, the Netherlands
| | - J B Boers
- Oncode Institue, Department of Developmental Biology, Erasmus MC, Rotterdam, the Netherlands
| | - C Dupont
- Oncode Institue, Department of Developmental Biology, Erasmus MC, Rotterdam, the Netherlands
| | - M E van Royen
- Department of Pathology, Erasmus MC, Rotterdam, the Netherlands
| | - W F J IJcken
- Center for Biomics, Department of Cell Biology, Erasmus MC, Rotterdam, the Netherlands
| | - P French
- Department of Neurology, Erasmus MC Cancer Institute, University Medical Center, Rotterdam, the Netherlands
| | - A Bedalov
- Clinical Research Division, Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue N., Seattle, WA 98109, USA
| | - J Gribnau
- Oncode Institue, Department of Developmental Biology, Erasmus MC, Rotterdam, the Netherlands.
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15
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Gene regulation in time and space during X-chromosome inactivation. Nat Rev Mol Cell Biol 2022; 23:231-249. [PMID: 35013589 DOI: 10.1038/s41580-021-00438-7] [Citation(s) in RCA: 80] [Impact Index Per Article: 40.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/18/2021] [Indexed: 12/21/2022]
Abstract
X-chromosome inactivation (XCI) is the epigenetic mechanism that ensures X-linked dosage compensation between cells of females (XX karyotype) and males (XY). XCI is essential for female embryos to survive through development and requires the accurate spatiotemporal regulation of many different factors to achieve remarkable chromosome-wide gene silencing. As a result of XCI, the active and inactive X chromosomes are functionally and structurally different, with the inactive X chromosome undergoing a major conformational reorganization within the nucleus. In this Review, we discuss the multiple layers of genetic and epigenetic regulation that underlie initiation of XCI during development and then maintain it throughout life, in light of the most recent findings in this rapidly advancing field. We discuss exciting new insights into the regulation of X inactive-specific transcript (XIST), the trigger and master regulator of XCI, and into the mechanisms and dynamics that underlie the silencing of nearly all X-linked genes. Finally, given the increasing interest in understanding the impact of chromosome organization on gene regulation, we provide an overview of the factors that are thought to reshape the 3D structure of the inactive X chromosome and of the relevance of such structural changes for XCI establishment and maintenance.
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16
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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] [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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17
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Early reactivation of clustered genes on the inactive X chromosome during somatic cell reprogramming. Stem Cell Reports 2021; 17:53-67. [PMID: 34919813 PMCID: PMC8758948 DOI: 10.1016/j.stemcr.2021.11.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2020] [Revised: 11/16/2021] [Accepted: 11/16/2021] [Indexed: 12/04/2022] Open
Abstract
Reprogramming of murine female somatic cells to induced pluripotent stem cells (iPSCs) is accompanied by X chromosome reactivation (XCR), by which the inactive X chromosome (Xi) in female somatic cells becomes reactivated. However, how Xi initiates reactivation during reprogramming remains poorly defined. Here, we used a Sendai virus-based reprogramming system to generate partially reprogrammed iPSCs that appear to be undergoing the initial phase of XCR. Allele-specific RNA-seq of these iPSCs revealed that XCR initiates at a subset of genes clustered near the centromere region. The initial phase of XCR occurs when the cells transit through mesenchymal-epithelial transition (MET) before complete shutoff of Xist expression. Moreover, regulatory regions of these genes display dynamic changes in lysine-demethylase 1a (KDM1A) occupancy. Our results identified clustered genes on the Xi that show reactivation in the initial phase of XCR during reprogramming and suggest a possible role for histone demethylation in this process. Partially reprogrammed iPSCs enabled analyses of early events in XCR XCR initiates at a subset of genes clustered near the centromere region XCR occurs before complete shutoff of Xist expression during reprogramming KDM1A inhibition appears to directly reactivate transcription from the Xi
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18
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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: 10] [Impact Index Per Article: 3.3] [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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19
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Bansal P, Ahern DT, Kondaveeti Y, Qiu CW, Pinter SF. Contiguous erosion of the inactive X in human pluripotency concludes with global DNA hypomethylation. Cell Rep 2021; 35:109215. [PMID: 34107261 PMCID: PMC8267460 DOI: 10.1016/j.celrep.2021.109215] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Revised: 08/18/2020] [Accepted: 05/13/2021] [Indexed: 01/21/2023] Open
Abstract
Female human pluripotent stem cells (hPSCs) routinely undergo inactive X (Xi) erosion. This progressive loss of key repressive features follows the loss of XIST expression, the long non-coding RNA driving X inactivation, and causes reactivation of silenced genes across the eroding X (Xe). To date, the sporadic and progressive nature of erosion has obscured its scale, dynamics, and key transition events. To address this problem, we perform an integrated analysis of DNA methylation (DNAme), chromatin accessibility, and gene expression across hundreds of hPSC samples. Differential DNAme orders female hPSCs across a trajectory from initiation to terminal Xi erosion. Our results identify a cis-regulatory element crucial for XIST expression, trace contiguously growing reactivated domains to a few euchromatic origins, and indicate that the late-stage Xe impairs DNAme genome-wide. Surprisingly, from this altered regulatory landscape emerge select features of naive pluripotency, suggesting that its link to X dosage may be partially conserved in human embryonic development. Reactivation of the silenced X in human female iPSC/ESCs compromises their utility. Bansal et al. perform an integrated genomics analysis to reveal a prevalent X erosion trajectory that they validate in long-term culture. Starting with XIST loss, this trajectory indicates that reactivation may spread contiguously from escapees to silenced genes.
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Affiliation(s)
- Prakhar Bansal
- Graduate Program in Genetics and Developmental Biology, UCONN Health, University of Connecticut, Farmington, CT, USA; Department of Genetics and Genome Sciences, UCONN Health, University of Connecticut, Farmington, CT, USA
| | - Darcy T Ahern
- Graduate Program in Genetics and Developmental Biology, UCONN Health, University of Connecticut, Farmington, CT, USA; Department of Genetics and Genome Sciences, UCONN Health, University of Connecticut, Farmington, CT, USA
| | - Yuvabharath Kondaveeti
- Department of Genetics and Genome Sciences, UCONN Health, University of Connecticut, Farmington, CT, USA
| | - Catherine W Qiu
- Department of Genetics and Genome Sciences, UCONN Health, University of Connecticut, Farmington, CT, USA
| | - Stefan F Pinter
- Graduate Program in Genetics and Developmental Biology, UCONN Health, University of Connecticut, Farmington, CT, USA; Department of Genetics and Genome Sciences, UCONN Health, University of Connecticut, Farmington, CT, USA; Institute for Systems Genomics, University of Connecticut, Farmington, CT, USA.
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20
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Mutzel V, Schulz EG. Dosage Sensing, Threshold Responses, and Epigenetic Memory: A Systems Biology Perspective on Random X-Chromosome Inactivation. Bioessays 2021; 42:e1900163. [PMID: 32189388 DOI: 10.1002/bies.201900163] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2019] [Revised: 01/27/2020] [Indexed: 02/06/2023]
Abstract
X-chromosome inactivation ensures dosage compensation between the sexes in mammals by randomly choosing one out of the two X chromosomes in females for inactivation. This process imposes a plethora of questions: How do cells count their X chromosome number and ensure that exactly one stays active? How do they randomly choose one of two identical X chromosomes for inactivation? And how do they stably maintain this state of monoallelic expression? Here, different regulatory concepts and their plausibility are evaluated in the context of theoretical studies that have investigated threshold behavior, ultrasensitivity, and bistability through mathematical modeling. It is discussed how a twofold difference between a single and a double dose of X-linked genes might be converted to an all-or-nothing response and how mutually exclusive expression can be initiated and maintained. Finally, candidate factors that might mediate the proposed regulatory principles are reviewed.
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Affiliation(s)
- Verena Mutzel
- Otto Warburg Laboratories, Max Planck Institute for Molecular Genetics, Berlin, 14195, Germany
| | - Edda G Schulz
- Otto Warburg Laboratories, Max Planck Institute for Molecular Genetics, Berlin, 14195, Germany
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21
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Giaimo BD, Robert-Finestra T, Oswald F, Gribnau J, Borggrefe T. Chromatin Regulator SPEN/SHARP in X Inactivation and Disease. Cancers (Basel) 2021; 13:cancers13071665. [PMID: 33916248 PMCID: PMC8036811 DOI: 10.3390/cancers13071665] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Revised: 03/26/2021] [Accepted: 03/26/2021] [Indexed: 12/14/2022] Open
Abstract
Simple Summary Carcinogenesis is a multistep process involving not only the activation of oncogenes and disabling tumor suppressor genes, but also epigenetic modulation of gene expression. X chromosome inactivation (XCI) is a paradigm to study heterochromatin formation and maintenance. The double dosage of X chromosomal genes in female mammals is incompatible with early development. XCI is an excellent model system for understanding the establishment of facultative heterochromatin initiated by the expression of a 17,000 nt long non-coding RNA, known as Xinactivespecifictranscript (Xist), on the X chromosome. This review focuses on the molecular mechanisms of how epigenetic modulators act in a step-wise manner to establish facultative heterochromatin, and we put these in the context of cancer biology and disease. An in depth understanding of XCI will allow a better characterization of particular types of cancer and hopefully facilitate the development of novel epigenetic therapies. Abstract Enzymes, such as histone methyltransferases and demethylases, histone acetyltransferases and deacetylases, and DNA methyltransferases are known as epigenetic modifiers that are often implicated in tumorigenesis and disease. One of the best-studied chromatin-based mechanism is X chromosome inactivation (XCI), a process that establishes facultative heterochromatin on only one X chromosome in females and establishes the right dosage of gene expression. The specificity factor for this process is the long non-coding RNA Xinactivespecifictranscript (Xist), which is upregulated from one X chromosome in female cells. Subsequently, Xist is bound by the corepressor SHARP/SPEN, recruiting and/or activating histone deacetylases (HDACs), leading to the loss of active chromatin marks such as H3K27ac. In addition, polycomb complexes PRC1 and PRC2 establish wide-spread accumulation of H3K27me3 and H2AK119ub1 chromatin marks. The lack of active marks and establishment of repressive marks set the stage for DNA methyltransferases (DNMTs) to stably silence the X chromosome. Here, we will review the recent advances in understanding the molecular mechanisms of how heterochromatin formation is established and put this into the context of carcinogenesis and disease.
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Affiliation(s)
- Benedetto Daniele Giaimo
- Institute of Biochemistry, University of Giessen, Friedrichstrasse 24, 35392 Giessen, Germany
- Correspondence: (B.D.G.); (T.B.); Tel.: +49-641-9947-400 (T.B.)
| | - Teresa Robert-Finestra
- Department of Developmental Biology, Erasmus MC, Oncode Institute, Wytemaweg 80, 3015 CN Rotterdam, The Netherlands; (T.R.-F.); (J.G.)
| | - Franz Oswald
- Center for Internal Medicine, Department of Internal Medicine I, University Medical Center Ulm, Albert-Einstein-Allee 23, 89081 Ulm, Germany;
| | - Joost Gribnau
- Department of Developmental Biology, Erasmus MC, Oncode Institute, Wytemaweg 80, 3015 CN Rotterdam, The Netherlands; (T.R.-F.); (J.G.)
| | - Tilman Borggrefe
- Institute of Biochemistry, University of Giessen, Friedrichstrasse 24, 35392 Giessen, Germany
- Correspondence: (B.D.G.); (T.B.); Tel.: +49-641-9947-400 (T.B.)
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22
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Westervelt N, Yoest A, Sayed S, Von Zimmerman M, Kaps K, Chadwick BP. Deletion of the XIST promoter from the human inactive X chromosome compromises polycomb heterochromatin maintenance. Chromosoma 2021; 130:177-197. [PMID: 33745031 DOI: 10.1007/s00412-021-00754-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Revised: 02/01/2021] [Accepted: 02/21/2021] [Indexed: 10/21/2022]
Abstract
Silencing most gene expression from all but one X chromosome in female mammals provides a means to overcome X-linked gene expression imbalances with males. Central to establishing gene silencing on the inactivated X chromosome are the actions of the long non-coding RNA XIST that triggers the repackaging of the chosen X into facultative heterochromatin. While understanding the mechanisms through which XIST expression is regulated and mediates its affects has been a major focus of research since its discovery, less is known about the role XIST plays in maintaining chromatin at the human inactive X chromosome (Xi). Here, we use genome engineering to delete the promoter of XIST to knockout expression from the Xi in non-cancerous diploid human somatic cells. Although some heterochromatin features exhibit limited change at the Xi, two of those assessed showed significant reductions including histone H2A monoubiquitylation at lysine 119 and histone H3 trimethylation at lysine 27, both of which are covalent histone modifications catalyzed by the polycomb repressive complexes 1 and 2 respectively. Coupled with these reductions, we observed an occasional gain of euchromatin signatures on Xp, but despite these signs of chromatin instability, we did not observe appreciable changes in the reactivation of genes from the Xi. Collectively, these data are consistent with maintenance of dosage compensation at the Xi involving multiple redundant layers of gene silencing.
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Affiliation(s)
- Natalia Westervelt
- Department of Biological Science, Florida State University, 319 Stadium Drive, King 3076, Tallahassee, FL, 32306-4295, USA
| | - Andrea Yoest
- Department of Biological Science, Florida State University, 319 Stadium Drive, King 3076, Tallahassee, FL, 32306-4295, USA
| | - Sadia Sayed
- Department of Biological Science, Florida State University, 319 Stadium Drive, King 3076, Tallahassee, FL, 32306-4295, USA
| | - Marina Von Zimmerman
- Department of Biological Science, Florida State University, 319 Stadium Drive, King 3076, Tallahassee, FL, 32306-4295, USA
| | - Kelly Kaps
- Department of Biological Science, Florida State University, 319 Stadium Drive, King 3076, Tallahassee, FL, 32306-4295, USA
| | - Brian P Chadwick
- Department of Biological Science, Florida State University, 319 Stadium Drive, King 3076, Tallahassee, FL, 32306-4295, USA.
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23
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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: 94] [Impact Index Per Article: 31.3] [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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24
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Ohhata T, Yamazawa K, Miura-Kamio A, Takahashi S, Sakai S, Tamura Y, Uchida C, Kitagawa K, Niida H, Hiratani I, Kobayashi H, Kimura H, Wutz A, Kitagawa M. Dynamics of transcription-mediated conversion from euchromatin to facultative heterochromatin at the Xist promoter by Tsix. Cell Rep 2021; 34:108912. [PMID: 33789104 DOI: 10.1016/j.celrep.2021.108912] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Revised: 10/08/2020] [Accepted: 03/05/2021] [Indexed: 02/07/2023] Open
Abstract
The fine-scale dynamics from euchromatin (EC) to facultative heterochromatin (fHC) has remained largely unclear. Here, we focus on Xist and its silencing initiator Tsix as a paradigm of transcription-mediated conversion from EC to fHC. In mouse epiblast stem cells, induction of Tsix recapitulates the conversion at the Xist promoter. Investigating the dynamics reveals that the conversion proceeds in a stepwise manner. Initially, a transient opened chromatin structure is observed. In the second step, gene silencing is initiated and dependent on Tsix, which is reversible and accompanied by simultaneous changes in multiple histone modifications. At the last step, maintenance of silencing becomes independent of Tsix and irreversible, which correlates with occupation of the -1 position of the transcription start site by a nucleosome and initiation of DNA methylation introduction. This study highlights the hierarchy of multiple chromatin events upon stepwise gene silencing establishment.
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Affiliation(s)
- Tatsuya Ohhata
- Department of Molecular Biology, Hamamatsu University School of Medicine, Hamamatsu 431-3192, Japan.
| | - Kazuki Yamazawa
- Medical Genetics Center, National Hospital Organization Tokyo Medical Center, Tokyo 152-8902, Japan
| | - Asuka Miura-Kamio
- NODAI Genome Research Center, Tokyo University of Agriculture, Tokyo 156-8502, Japan
| | - Saori Takahashi
- Laboratory for Developmental Epigenetics, RIKEN Center for Biosystems Dynamics Research (BDR), Kobe 650-0047, Japan
| | - Satoshi Sakai
- Department of Molecular Biology, Hamamatsu University School of Medicine, Hamamatsu 431-3192, Japan
| | - Yuka Tamura
- Department of Molecular Biology, Hamamatsu University School of Medicine, Hamamatsu 431-3192, Japan
| | - Chiharu Uchida
- Advanced Research Facilities & Services, Preeminent Medical Photonics Education & Research Center, Hamamatsu University School of Medicine, Hamamatsu 431-3192, Japan
| | - Kyoko Kitagawa
- Department of Molecular Biology, Hamamatsu University School of Medicine, Hamamatsu 431-3192, Japan
| | - Hiroyuki Niida
- Department of Molecular Biology, Hamamatsu University School of Medicine, Hamamatsu 431-3192, Japan
| | - Ichiro Hiratani
- Laboratory for Developmental Epigenetics, RIKEN Center for Biosystems Dynamics Research (BDR), Kobe 650-0047, Japan
| | - Hisato Kobayashi
- NODAI Genome Research Center, Tokyo University of Agriculture, Tokyo 156-8502, Japan
| | - Hiroshi Kimura
- Cell Biology Center, Institute of Innovative Research, Tokyo Institute of Technology, Yokohama 226-8503, Japan
| | - Anton Wutz
- Institute of Molecular Health Sciences, Swiss Federal Institute of Technology, ETH Hönggerberg, Otto-Stern-Weg 7, 8093 Zurich, Switzerland
| | - Masatoshi Kitagawa
- Department of Molecular Biology, Hamamatsu University School of Medicine, Hamamatsu 431-3192, Japan.
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25
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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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26
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Moscatelli M, Rougeulle C. [Latest insights on X-chromosome inactivation: When general principles should be revisited]. Med Sci (Paris) 2021; 37:152-158. [PMID: 33591258 DOI: 10.1051/medsci/2020278] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The inactivation of one of the two X chromosomes of female mammals is a vital process and a paradigm for epigenetic regulations. X-inactivation is triggered, early during embryo development, by the accumulation of a peculiar noncoding RNA, XIST, which interacts with a plethora of molecular complexes and ultimately protects the coated chromosome from the expression machinery. Once installed, the inactive state is locked by multiple layers of chromatin modifications, ensuring its stable perpetuation across cell divisions. However, recent discoveries made in various model organisms urge us to revisit some of the general principles of the X-inactivation process.
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Affiliation(s)
- Madeleine Moscatelli
- Université de Paris, Épigénétique et Destin Cellulaire, CNRS, F-75006 Paris, France
| | - Claire Rougeulle
- Université de Paris, Épigénétique et Destin Cellulaire, CNRS, F-75006 Paris, France
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27
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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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28
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Panda A, Zylicz JJ, Pasque V. New Insights into X-Chromosome Reactivation during Reprogramming to Pluripotency. Cells 2020; 9:E2706. [PMID: 33348832 PMCID: PMC7766869 DOI: 10.3390/cells9122706] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2020] [Revised: 12/08/2020] [Accepted: 12/10/2020] [Indexed: 02/06/2023] Open
Abstract
Dosage compensation between the sexes results in one X chromosome being inactivated during female mammalian development. Chromosome-wide transcriptional silencing from the inactive X chromosome (Xi) in mammalian cells is erased in a process termed X-chromosome reactivation (XCR), which has emerged as a paradigm for studying the reversal of chromatin silencing. XCR is linked with germline development and induction of naive pluripotency in the epiblast, and also takes place upon reprogramming somatic cells to induced pluripotency. XCR depends on silencing of the long non-coding RNA (lncRNA) X inactive specific transcript (Xist) and is linked with the erasure of chromatin silencing. Over the past years, the advent of transcriptomics and epigenomics has provided new insights into the transcriptional and chromatin dynamics with which XCR takes place. However, multiple questions remain unanswered about how chromatin and transcription related processes enable XCR. Here, we review recent work on establishing the transcriptional and chromatin kinetics of XCR, as well as discuss a model by which transcription factors mediate XCR not only via Xist repression, but also by direct targeting of X-linked genes.
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Affiliation(s)
- Amitesh Panda
- Laboratory of Cellular Reprogramming and Epigenetic Regulation, Department of Development and Regeneration, Leuven Stem Cell Institute, KU Leuven-University of Leuven, 3000 Leuven, Belgium;
| | - Jan J. Zylicz
- The Novo Nordisk Foundation Center for Stem Cell Biology, University of Copenhagen, 2200 Copenhagen, Denmark;
| | - Vincent Pasque
- Laboratory of Cellular Reprogramming and Epigenetic Regulation, Department of Development and Regeneration, Leuven Stem Cell Institute, KU Leuven-University of Leuven, 3000 Leuven, Belgium;
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Hagen SH, Henseling F, Hennesen J, Savel H, Delahaye S, Richert L, Ziegler SM, Altfeld M. Heterogeneous Escape from X Chromosome Inactivation Results in Sex Differences in Type I IFN Responses at the Single Human pDC Level. Cell Rep 2020; 33:108485. [PMID: 33296655 PMCID: PMC7833293 DOI: 10.1016/j.celrep.2020.108485] [Citation(s) in RCA: 68] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Revised: 09/11/2020] [Accepted: 11/12/2020] [Indexed: 12/28/2022] Open
Abstract
Immune responses differ between women and men, and type I interferon (IFN) responses following Toll-like receptor 7 (TLR7) stimulation are higher in women. The precise mechanisms driving these sex differences in immunity are unknown. To investigate possible genetic factors, we quantify escape from X chromosome inactivation (XCI) for TLR7 and four other genes (RPS6KA3, CYBB, BTK, and IL13RA1) at the single plasmacytoid dendritic cell (pDC) level. We observe escape from XCI for all investigated genes, leading to biallelic expression patterns. pDCs with biallelic gene expression have significantly higher mRNA levels of the respective genes. Unstimulated pDCs with biallelic TLR7 expression exhibit significantly higher IFNα/β mRNA levels, and IFNα exposure results in significantly increased IFNα/β protein production by pDCs. These results identify unanticipated heterogeneity in escape from XCI of several genes in pDCs and highlight the important contribution of X chromosome factors to sex differences in type I IFN responses, which might explain observed sex differences in human diseases.
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Affiliation(s)
- Sven Hendrik Hagen
- Research Department Virus Immunology, Heinrich Pette Institute, Leibniz Institute for Experimental Virology, Martinistrasse 52, Hamburg 20251, Germany
| | - Florian Henseling
- Research Department Virus Immunology, Heinrich Pette Institute, Leibniz Institute for Experimental Virology, Martinistrasse 52, Hamburg 20251, Germany
| | - Jana Hennesen
- Technology Platform Flow Cytometry/FACS, Heinrich Pette Institute, Leibniz Institute for Experimental Virology, Martinistrasse 52, Hamburg 20251, Germany
| | - Hélène Savel
- University of Bordeaux, Inserm, Bordeaux Population Health Research Center, UMR1219 and Inria, team SISTM, Bordeaux, France
| | - Solenne Delahaye
- University of Bordeaux, Inserm, Bordeaux Population Health Research Center, UMR1219 and Inria, team SISTM, Bordeaux, France
| | - Laura Richert
- University of Bordeaux, Inserm, Bordeaux Population Health Research Center, UMR1219 and Inria, team SISTM, Bordeaux, France
| | - Susanne Maria Ziegler
- Research Department Virus Immunology, Heinrich Pette Institute, Leibniz Institute for Experimental Virology, Martinistrasse 52, Hamburg 20251, Germany
| | - Marcus Altfeld
- Research Department Virus Immunology, Heinrich Pette Institute, Leibniz Institute for Experimental Virology, Martinistrasse 52, Hamburg 20251, Germany.
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30
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Wang D, Tang L, Wu Y, Fan C, Zhang S, Xiang B, Zhou M, Li X, Li Y, Li G, Xiong W, Zeng Z, Guo C. Abnormal X chromosome inactivation and tumor development. Cell Mol Life Sci 2020; 77:2949-2958. [PMID: 32040694 PMCID: PMC11104905 DOI: 10.1007/s00018-020-03469-z] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2019] [Revised: 01/17/2020] [Accepted: 01/21/2020] [Indexed: 12/13/2022]
Abstract
During embryonic development, one of the two X chromosomes of a mammalian female cell is randomly inactivated by the X chromosome inactivation mechanism, which is mainly dependent on the regulation of the non-coding RNA X-inactive specific transcript at the X chromosome inactivation center. There are three proteins that are essential for X-inactive specific transcript to function properly: scaffold attachment factor-A, lamin B receptor, and SMRT- and HDAC-associated repressor protein. In addition, the absence of X-inactive specific transcript expression promotes tumor development. During the process of chromosome inactivation, some tumor suppressor genes escape inactivation of the X chromosome and thereby continue to play a role in tumor suppression. A well-functioning tumor suppressor gene on the idle X chromosome in women is one of the reasons they have a lower propensity to develop cancer than men, women thereby benefit from this enhanced tumor suppression. This review will explore the mechanism of X chromosome inactivation, discuss the relationship between X chromosome inactivation and tumorigenesis, and consider the consequent sex differences in cancer.
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Affiliation(s)
- Dan Wang
- Department of Stomatology, NHC Key Laboratory of Carcinogenesis, Xiangya Hospital, Central South University, Changsha, Hunan, China
- Key Laboratory of Carcinogenesis and Cancer Invasion of the Chinese Ministry of Education, Cancer Research Institute, Central South University, Changsha, Hunan, China
- Hunan Key Laboratory of Nonresolving Inflammation and Cancer, Disease Genome Research Center, The Third Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Le Tang
- Key Laboratory of Carcinogenesis and Cancer Invasion of the Chinese Ministry of Education, Cancer Research Institute, Central South University, Changsha, Hunan, China
| | - Yingfen Wu
- Key Laboratory of Carcinogenesis and Cancer Invasion of the Chinese Ministry of Education, Cancer Research Institute, Central South University, Changsha, Hunan, China
| | - Chunmei Fan
- Key Laboratory of Carcinogenesis and Cancer Invasion of the Chinese Ministry of Education, Cancer Research Institute, Central South University, Changsha, Hunan, China
| | - Shanshan Zhang
- Department of Stomatology, NHC Key Laboratory of Carcinogenesis, Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Bo Xiang
- Key Laboratory of Carcinogenesis and Cancer Invasion of the Chinese Ministry of Education, Cancer Research Institute, Central South University, Changsha, Hunan, China
| | - Ming Zhou
- Key Laboratory of Carcinogenesis and Cancer Invasion of the Chinese Ministry of Education, Cancer Research Institute, Central South University, Changsha, Hunan, China
| | - Xiaoling Li
- Key Laboratory of Carcinogenesis and Cancer Invasion of the Chinese Ministry of Education, Cancer Research Institute, Central South University, Changsha, Hunan, China
| | - Yong Li
- Department of Medicine, Dan L Duncan Comprehensive Cancer Center, Baylor College of Medicine, Houston, Texas, USA
| | - Guiyuan Li
- Key Laboratory of Carcinogenesis and Cancer Invasion of the Chinese Ministry of Education, Cancer Research Institute, Central South University, Changsha, Hunan, China
| | - Wei Xiong
- Key Laboratory of Carcinogenesis and Cancer Invasion of the Chinese Ministry of Education, Cancer Research Institute, Central South University, Changsha, Hunan, China
| | - Zhaoyang Zeng
- Key Laboratory of Carcinogenesis and Cancer Invasion of the Chinese Ministry of Education, Cancer Research Institute, Central South University, Changsha, Hunan, China
| | - Can Guo
- Department of Stomatology, NHC Key Laboratory of Carcinogenesis, Xiangya Hospital, Central South University, Changsha, Hunan, China.
- Key Laboratory of Carcinogenesis and Cancer Invasion of the Chinese Ministry of Education, Cancer Research Institute, Central South University, Changsha, Hunan, China.
- Hunan Key Laboratory of Nonresolving Inflammation and Cancer, Disease Genome Research Center, The Third Xiangya Hospital, Central South University, Changsha, Hunan, China.
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31
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Żylicz JJ, Heard E. Molecular Mechanisms of Facultative Heterochromatin Formation: An X-Chromosome Perspective. Annu Rev Biochem 2020; 89:255-282. [PMID: 32259458 DOI: 10.1146/annurev-biochem-062917-012655] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Facultative heterochromatin (fHC) concerns the developmentally regulated heterochromatinization of different regions of the genome and, in the case of the mammalian X chromosome and imprinted loci, of only one allele of a homologous pair. The formation of fHC participates in the timely repression of genes, by resisting strong trans activators. In this review, we discuss the molecular mechanisms underlying the establishment and maintenance of fHC in mammals using a mouse model. We focus on X-chromosome inactivation (XCI) as a paradigm for fHC but also relate it to genomic imprinting and homeobox (Hox) gene cluster repression. A vital role for noncoding transcription and/or transcripts emerges as the general principle of triggering XCI and canonical imprinting. However, other types of fHC are established through an unknown mechanism, independent of noncoding transcription (Hox clusters and noncanonical imprinting). We also extensively discuss polycomb-group repressive complexes (PRCs), which frequently play a vital role in fHC maintenance.
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Affiliation(s)
- Jan J Żylicz
- Mammalian Developmental Epigenetics Group, Institut Curie, CNRS UMR 3215, INSERM U934, PSL University, 75248 Paris Cedex 05, France.,Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3EL, United Kingdom
| | - Edith Heard
- Directors' Research, EMBL Heidelberg, 69117 Heidelberg, Germany;
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32
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Strehle M, Guttman M. Xist drives spatial compartmentalization of DNA and protein to orchestrate initiation and maintenance of X inactivation. Curr Opin Cell Biol 2020; 64:139-147. [PMID: 32535328 DOI: 10.1016/j.ceb.2020.04.009] [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: 01/13/2020] [Revised: 04/13/2020] [Accepted: 04/23/2020] [Indexed: 12/15/2022]
Abstract
X chromosome inactivation (XCI) is the process whereby one of the X chromosomes in female mammalian cells is silenced to equalize X-linked gene expression with males. XCI depends on the long noncoding RNA Xist, which coats the inactive X chromosome in cis and triggers a cascade of events that ultimately lead to chromosome-wide transcriptional silencing that is stable for the lifetime of an organism. In recent years, the discovery of proteins that interact with Xist have led to new insights into how the initiation of XCI occurs. Nevertheless, there are still various unknowns about the mechanisms by which Xist orchestrates and maintains stable X-linked silencing. Here, we review recent work elucidating the role of Xist and its protein partners in mediating chromosome-wide transcriptional repression, as well as discuss a model by which Xist may compartmentalize proteins across the inactive X chromosome to enable both the initiation and maintenance of XCI.
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Affiliation(s)
- Mackenzie Strehle
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Mitchell Guttman
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA.
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33
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Abstract
The X inactive-specific transcript (Xist) gene is the master regulator of X chromosome inactivation in mammals. Xist produces a long noncoding (lnc)RNA that accumulates over the entire length of the chromosome from which it is transcribed, recruiting factors to modify underlying chromatin and silence X-linked genes in cis Recent years have seen significant progress in identifying important functional elements in Xist RNA, their associated RNA-binding proteins (RBPs), and the downstream pathways for chromatin modification and gene silencing. In this review, we summarize progress in understanding both how these pathways function in Xist-mediated silencing and the complex interplay between them.
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Affiliation(s)
- Neil Brockdorff
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, United Kingdom
| | - Joseph S Bowness
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, United Kingdom
| | - Guifeng Wei
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, United Kingdom
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34
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Wistuba J, Beumer C, Brehm R, Gromoll J. 41,XX Y * male mice: An animal model for Klinefelter syndrome. AMERICAN JOURNAL OF MEDICAL GENETICS PART C-SEMINARS IN MEDICAL GENETICS 2020; 184:267-278. [PMID: 32432406 DOI: 10.1002/ajmg.c.31796] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2020] [Revised: 04/28/2020] [Accepted: 04/29/2020] [Indexed: 12/25/2022]
Abstract
Klinefelter syndrome (KS, 47,XXY) is the most frequent male chromosomal aneuploidy resulting in a highly heterogeneous clinical phenotype associated with hormonal dysbalance, increased rate of co-morbidities, and reduced lifespan. Two hallmarks of KS-affecting testicular functions are consistently observed: Hypergonadotropic hypogonadism and germ cell (GC) loss resulting in infertility. Although KS is being studied for decades, the underlying mechanisms for the observed pathophysiology are still unclear. Due to ethical restrictions, studies in humans are limited, and consequently, suitable animal models are needed to address the consequences of a supernumerary X chromosome. Mouse strains with comparable aneuploidies have been generated and yielded highly relevant insights into KS. We briefly describe the establishment of the KS mouse models, summarize the knowledge gained by their use, compare findings from the mouse models to those obtained in clinical studies, and also reflect on limitations of the currently used models derived from the B6Ei.Lt-Y* mouse strain, in which the Y chromosome is altered and its centromere position changed into a more distal location provoking meiotic non-disjunction. Breeding such as XY* males to XX females, the target 41,XXY *, and 41,XXY males are generated. Here, we summarize features of both models but report in particular findings from our 41,XXY * mice including some novel data on Sertoli cell characteristics.
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Affiliation(s)
- Joachim Wistuba
- Institute of Reproductive and Regenerative Biology, Centre of Reproductive Medicine and Andrology, University of Münster, Münster, Germany
| | - Cristin Beumer
- Institute of Reproductive and Regenerative Biology, Centre of Reproductive Medicine and Andrology, University of Münster, Münster, Germany
| | - Ralph Brehm
- Functional Histology and Cell Biology, Institute for Anatomy, University of Veterinary Medicine Hannover, Foundation, Hannover, Germany
| | - Jörg Gromoll
- Institute of Reproductive and Regenerative Biology, Centre of Reproductive Medicine and Andrology, University of Münster, Münster, Germany
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35
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Widespread organ tolerance to Xist loss and X reactivation except under chronic stress in the gut. Proc Natl Acad Sci U S A 2020; 117:4262-4272. [PMID: 32041873 DOI: 10.1073/pnas.1917203117] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Long thought to be dispensable after establishing X chromosome inactivation (XCI), Xist RNA is now known to also maintain the inactive X (Xi). To what extent somatic X reactivation causes physiological abnormalities is an active area of inquiry. Here, we use multiple mouse models to investigate in vivo consequences. First, when Xist is deleted systemically in post-XCI embryonic cells using the Meox2-Cre driver, female pups exhibit no morbidity or mortality despite partial X reactivation. Second, when Xist is conditionally deleted in epithelial cells using Keratin14-Cre or in B cells using CD19-Cre, female mice have a normal life span without obvious illness. Third, when Xist is deleted in gut using Villin-Cre, female mice remain healthy despite significant X-autosome dosage imbalance. Finally, when the gut is acutely stressed by azoxymethane/dextran sulfate (AOM/DSS) exposure, both Xist-deleted and wild-type mice develop gastrointestinal tumors. Intriguingly, however, under prolonged stress, mutant mice develop larger tumors and have a higher tumor burden. The effect is female specific. Altogether, these observations reveal a surprising systemic tolerance to Xist loss but importantly reveal that Xist and XCI are protective to females during chronic stress.
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36
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Bansal P, Kondaveeti Y, Pinter SF. Forged by DXZ4, FIRRE, and ICCE: How Tandem Repeats Shape the Active and Inactive X Chromosome. Front Cell Dev Biol 2020; 7:328. [PMID: 32076600 PMCID: PMC6985041 DOI: 10.3389/fcell.2019.00328] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Accepted: 11/26/2019] [Indexed: 12/11/2022] Open
Abstract
Recent efforts in mapping spatial genome organization have revealed three evocative and conserved structural features of the inactive X in female mammals. First, the chromosomal conformation of the inactive X reveals a loss of topologically associated domains (TADs) present on the active X. Second, the macrosatellite DXZ4 emerges as a singular boundary that suppresses physical interactions between two large TAD-depleted "megadomains." Third, DXZ4 reaches across several megabases to form "superloops" with two other X-linked tandem repeats, FIRRE and ICCE, which also loop to each other. Although all three structural features are conserved across rodents and primates, deletion of mouse and human orthologs of DXZ4 and FIRRE from the inactive X have revealed limited impact on X chromosome inactivation (XCI) and escape in vitro. In contrast, loss of Xist or SMCHD1 have been shown to impair TAD erasure and gene silencing on the inactive X. In this perspective, we summarize these results in the context of new research describing disruption of X-linked tandem repeats in vivo, and discuss their possible molecular roles through the lens of evolutionary conservation and clinical genetics. As a null hypothesis, we consider whether the conservation of some structural features on the inactive X may reflect selection for X-linked tandem repeats on account of necessary cis- and trans-regulatory roles they may play on the active X, rather than the inactive X. Additional hypotheses invoking a role for X-linked tandem repeats on X reactivation, for example in the germline or totipotency, remain to be assessed in multiple developmental models spanning mammalian evolution.
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Affiliation(s)
- Prakhar Bansal
- Department of Genetics and Genome Sciences, School of Medicine, UCONN Health, University of Connecticut, Farmington, CT, United States
- Institute for Systems Genomics, University of Connecticut, Farmington, CT, United States
| | - Yuvabharath Kondaveeti
- Department of Genetics and Genome Sciences, School of Medicine, UCONN Health, University of Connecticut, Farmington, CT, United States
- Institute for Systems Genomics, University of Connecticut, Farmington, CT, United States
| | - Stefan F. Pinter
- Department of Genetics and Genome Sciences, School of Medicine, UCONN Health, University of Connecticut, Farmington, CT, United States
- Institute for Systems Genomics, University of Connecticut, Farmington, CT, United States
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37
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Talon I, Janiszewski A, Chappell J, Vanheer L, Pasque V. Recent Advances in Understanding the Reversal of Gene Silencing During X Chromosome Reactivation. Front Cell Dev Biol 2019; 7:169. [PMID: 31552244 PMCID: PMC6733891 DOI: 10.3389/fcell.2019.00169] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Accepted: 08/07/2019] [Indexed: 12/24/2022] Open
Abstract
Dosage compensation between XX female and XY male cells is achieved by a process known as X chromosome inactivation (XCI) in mammals. XCI is initiated early during development in female cells and is subsequently stably maintained in most somatic cells. Despite its stability, the robust transcriptional silencing of XCI is reversible, in the embryo and also in a number of reprogramming settings. Although XCI has been intensively studied, the dynamics, factors, and mechanisms of X chromosome reactivation (XCR) remain largely unknown. In this review, we discuss how new sequencing technologies and reprogramming approaches have enabled recent advances that revealed the timing of transcriptional activation during XCR. We also discuss the factors and chromatin features that might be important to understand the dynamics and mechanisms of the erasure of transcriptional gene silencing on the inactive X chromosome (Xi).
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Affiliation(s)
| | | | | | | | - Vincent Pasque
- Department of Development and Regeneration, Leuven Stem Cell Institute, KU Leuven, Leuven, Belgium
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38
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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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39
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Sato H, Wu B, Delahaye F, Singer RH, Greally JM. Retargeting of macroH2A following mitosis to cytogenetic-scale heterochromatic domains. J Cell Biol 2019; 218:1810-1823. [PMID: 31110057 PMCID: PMC6548134 DOI: 10.1083/jcb.201811109] [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: 11/20/2018] [Revised: 03/20/2019] [Accepted: 04/19/2019] [Indexed: 12/12/2022] Open
Abstract
How macroH2A, a histone variant involved in silencing gene expression, is inherited from parent to daughter cells is unclear. Using a combination of imaging, biochemical, and genomic approaches, Sato et al. describe how newly synthesized macroH2A is incorporated predominantly in the G1 phase of human mitosis, targeting heterochromatic regions. The heritability of chromatin states through cell division is a potential contributor to the epigenetic maintenance of cellular memory of prior states. The macroH2A histone variant has properties of a regulator of epigenetic cell memory, including roles controlling gene silencing and cell differentiation. Its mechanisms of regional genomic targeting and maintenance through cell division are unknown. Here, we combined in vivo imaging with biochemical and genomic approaches to show that human macroH2A is incorporated into chromatin in the G1 phase of the cell cycle following DNA replication. The newly incorporated macroH2A retargets the same large heterochromatic domains where macroH2A was already enriched in the previous cell cycle. It remains heterotypic, targeting individual nucleosomes that do not already contain a macroH2A molecule. The pattern observed resembles that of a new deposition of centromeric histone variants during the cell cycle, indicating mechanistic similarities for macrodomain-scale regulation of epigenetic properties of the cell.
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Affiliation(s)
- Hanae Sato
- Center for Epigenomics and Department of Genetics, Albert Einstein College of Medicine, Bronx, NY.,Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, NY
| | - Bin Wu
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, NY.,Gruss Lipper Biophotonics Center, Albert Einstein College of Medicine, Bronx, NY
| | - Fabien Delahaye
- Center for Epigenomics and Department of Genetics, Albert Einstein College of Medicine, Bronx, NY.,Department of Obstetrics and Gynecology and Women's Health, Albert Einstein College of Medicine, Bronx, NY
| | - Robert H Singer
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, NY .,Gruss Lipper Biophotonics Center, Albert Einstein College of Medicine, Bronx, NY.,Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY.,Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA
| | - John M Greally
- Center for Epigenomics and Department of Genetics, Albert Einstein College of Medicine, Bronx, NY
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40
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Sierra I, Anguera MC. Enjoy the silence: X-chromosome inactivation diversity in somatic cells. Curr Opin Genet Dev 2019; 55:26-31. [PMID: 31108425 DOI: 10.1016/j.gde.2019.04.012] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Revised: 03/19/2019] [Accepted: 04/15/2019] [Indexed: 12/15/2022]
Abstract
The imbalance of sex chromosomes between females (XX) and males (XY) necessitates strict regulation of X-linked gene expression. X-Chromosome Inactivation (XCI) selects one X for transcriptional silencing in the early embryo, generating an epigenetically distinct and transcriptionally silent X that is maintained into adulthood. Some genes on the inactive X escape XCI, and human somatic cells have a greater number of escape genes compared to mice. Advances with single-cell technologies have revealed human-specific escape genes in fibroblasts and immune cells, some of which exhibit cell and tissue specificity. Here, we review recent discoveries of dynamic XCI in female immune cells, which have changed our understanding of XCI maintenance, and discuss how some X-linked genes might become overexpressed in female-biased autoimmunity.
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Affiliation(s)
- Isabel Sierra
- Department of Biomedical Sciences, School of Veterinary Medicine, University of Pennsylvania, PA 19104, USA
| | - Montserrat C Anguera
- Department of Biomedical Sciences, School of Veterinary Medicine, University of Pennsylvania, PA 19104, USA.
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41
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Histone variant macroH2A: from chromatin deposition to molecular function. Essays Biochem 2019; 63:59-74. [DOI: 10.1042/ebc20180062] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2019] [Revised: 02/28/2019] [Accepted: 03/01/2019] [Indexed: 01/01/2023]
Abstract
Abstract
The eukaryotic genome is regulated in the context of chromatin. Specialized histones, known as histone variants, incorporate into chromatin to replace their canonical counterparts and represent an important layer of regulation to diversify the structural characteristics and functional outputs of chromatin. MacroH2A is an unusual histone variant with a bulky C-terminal non-histone domain that distinguishes it from all other histones. It is a critical player in stabilizing differentiated cell identity by posing as a barrier to somatic cell reprogramming toward pluripotency and acts as a tumor suppressor in a wide range of cancers. MacroH2A histones are generally regarded as repressive variants that are enriched at the inactive X chromosome (Xi) and broad domains across autosomal chromatin. Recent studies have shed light on to how macroH2A influences transcriptional outputs within distinct genomic contexts and revealed new intriguing molecular functions of macroH2A variants beyond transcriptional regulation. Furthermore, the mechanisms of its mysterious chromatin deposition are beginning to be unraveled, facilitating our understanding of its complex regulation of genome function.
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42
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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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43
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Xist/Tsix expression dynamics during mouse peri-implantation development revealed by whole-mount 3D RNA-FISH. Sci Rep 2019; 9:3637. [PMID: 30842444 PMCID: PMC6403393 DOI: 10.1038/s41598-019-38807-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Accepted: 12/11/2018] [Indexed: 12/31/2022] Open
Abstract
During peri-implantation development in mice, X chromosome inactivation (XCI) status changes dynamically. Here, we examined the expression of Xist and its antisense partner, Tsix, via whole-mount 3D RNA-FISH using strand-specific probes and evaluated XCI status. The results indicate that Xist expression disappears completely by embryonic day (E) 4.5 without Tsix activation in the ICM and that Xist re-expression occurs at E4.75 in some cells, suggesting that random XCI is already initiated in these cells. Intriguingly, epiblast cells exhibiting biallelic Xist expression were observed frequently (~15%) at E5.25 and E5.5. Immunostaining analysis of epigenetic modifications suggests that global change in epigenomic status occurs concomitantly with the transition from imprinted to random XCI. However, global upregulation of H3K27me3 modifications initiated earlier than other modifications, occurring specifically in ICM during progression of Xist erasure. Although both Xist expression and imprinted XCI are thought to be stable in the primitive endoderm/visceral endoderm and trophectoderm/extraembryonic ectoderm lineages, transient loss of Xist clouds was noted only in a subset of extraembryonic ectodermal cells, suggesting distinct features of Xist regulation among the three different embryonic tissue layers. These results will serve as a basis for future functional studies of XCI regulation in vivo.
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44
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Peeters SB, Korecki AJ, Simpson EM, Brown CJ. Human cis-acting elements regulating escape from X-chromosome inactivation function in mouse. Hum Mol Genet 2019; 27:1252-1262. [PMID: 29401310 PMCID: PMC6159535 DOI: 10.1093/hmg/ddy039] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2017] [Accepted: 01/29/2018] [Indexed: 12/18/2022] Open
Abstract
A long-standing question concerning X-chromosome inactivation (XCI) has been how some genes avoid the otherwise stable chromosome-wide heterochromatinization of the inactive X chromosome. As 20% or more of human X-linked genes escape from inactivation, such genes are an important contributor to sex differences in gene expression. Although both human and mouse have genes that escape from XCI, more genes escape in humans than mice, with human escape genes often clustering in larger domains than the single escape genes of mouse. Mouse models offer a well-characterized and readily manipulated system in which to study XCI, but given the differences in genes that escape it is unclear whether the mechanism of escape gene regulation is conserved. To address conservation of the process and the potential to identify elements by modelling human escape gene regulation using mouse, we integrated a human and a mouse BAC each containing an escape gene and flanking subject genes at the mouse X-linked Hprt gene. Escape-level expression and corresponding low promoter DNA methylation of human genes RPS4X and CITED1 demonstrated that the mouse system is capable of recognizing human elements and therefore can be used as a model for further refinement of critical elements necessary for escape from XCI in humans.
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Affiliation(s)
- Samantha B Peeters
- Department of Medical Genetics, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - Andrea J Korecki
- Centre for Molecular Medicine and Therapeutics at British Columbia Children's Hospital, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - Elizabeth M Simpson
- Centre for Molecular Medicine and Therapeutics at British Columbia Children's Hospital, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
| | - Carolyn J Brown
- Department of Medical Genetics, University of British Columbia, Vancouver, BC V6T 1Z4, Canada
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45
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Jégu T, Blum R, Cochrane JC, Yang L, Wang CY, Gilles ME, Colognori D, Szanto A, Marr SK, Kingston RE, Lee JT. Xist RNA antagonizes the SWI/SNF chromatin remodeler BRG1 on the inactive X chromosome. Nat Struct Mol Biol 2019; 26:96-109. [PMID: 30664740 PMCID: PMC6421574 DOI: 10.1038/s41594-018-0176-8] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Accepted: 12/03/2018] [Indexed: 02/08/2023]
Abstract
The noncoding RNA Xist recruits silencing factors to the inactive X chromosome (Xi) and facilitates re-organization of Xi structure. Here, we examine the mouse epigenomic landscape of Xi and assess how Xist alters chromatin accessibility. Interestingly, Xist deletion triggers a gain of accessibility of selective chromatin regions that is regulated by BRG1, an ATPase subunit of the SWI/SNF chromatin remodeling complex. In vitro, RNA binding inhibits nucleosome remodeling and ATPase activities of BRG1, while in cell culture Xist directly interacts with BRG1 and expels BRG1 from the Xi. Xist ablation leads to a selective return of BRG1 in cis, starting from pre-existing BRG1 sites that are free of Xist. BRG1 re-association correlates with cohesin binding and restoration of topologically associated domains (TADs), and results in formation of de novo Xi “superloops.” Thus, Xist binding inhibits BRG1’s nucleosome remodeling activity and results in expulsion of the SWI/SNF complex from the Xi.
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Affiliation(s)
- Teddy Jégu
- Howard Hughes Medical Institute, Boston, MA, USA.,Department of Molecular Biology, Massachusetts General Hospital, Boston, MA, USA.,Department of Genetics, Harvard Medical School, Boston, MA, USA
| | - Roy Blum
- Howard Hughes Medical Institute, Boston, MA, USA.,Department of Molecular Biology, Massachusetts General Hospital, Boston, MA, USA.,Department of Genetics, Harvard Medical School, Boston, MA, USA
| | - Jesse C Cochrane
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA, USA.,Department of Genetics, Harvard Medical School, Boston, MA, USA
| | - Lin Yang
- Howard Hughes Medical Institute, Boston, MA, USA.,Department of Molecular Biology, Massachusetts General Hospital, Boston, MA, USA.,Department of Genetics, Harvard Medical School, Boston, MA, USA
| | - Chen-Yu Wang
- Howard Hughes Medical Institute, Boston, MA, USA.,Department of Molecular Biology, Massachusetts General Hospital, Boston, MA, USA.,Department of Genetics, Harvard Medical School, Boston, MA, USA
| | - Maud-Emmanuelle Gilles
- Institute for RNA Medicine, Department of Pathology, Cancer Center, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - David Colognori
- Howard Hughes Medical Institute, Boston, MA, USA.,Department of Molecular Biology, Massachusetts General Hospital, Boston, MA, USA.,Department of Genetics, Harvard Medical School, Boston, MA, USA
| | - Attila Szanto
- Howard Hughes Medical Institute, Boston, MA, USA.,Department of Molecular Biology, Massachusetts General Hospital, Boston, MA, USA.,Department of Genetics, Harvard Medical School, Boston, MA, USA
| | - Sharon K Marr
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA, USA.,Department of Genetics, Harvard Medical School, Boston, MA, USA
| | - Robert E Kingston
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA, USA.,Department of Genetics, Harvard Medical School, Boston, MA, USA
| | - Jeannie T Lee
- Howard Hughes Medical Institute, Boston, MA, USA. .,Department of Molecular Biology, Massachusetts General Hospital, Boston, MA, USA. .,Department of Genetics, Harvard Medical School, Boston, MA, USA.
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46
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MacroH2A1 chromatin specification requires its docking domain and acetylation of H2B lysine 20. Nat Commun 2018; 9:5143. [PMID: 30510186 PMCID: PMC6277393 DOI: 10.1038/s41467-018-07189-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2017] [Accepted: 10/13/2018] [Indexed: 12/23/2022] Open
Abstract
The histone variant macroH2A1 localizes to two functionally distinct chromatin subtypes marked by either H3K27me3 or H2B acetylations, where it is thought to directly regulate transcription. The recent finding, that macroH2A1 regulates mitochondrial respiration by globally dampening PARP activity, requires the field to re-evaluate which functions of macroH2A1 are due to global effects on cellular metabolism and which are direct effects determined by macroH2A1 chromatin localization. Here, we demonstrate macroH2A1 incorporation into H2B-acetylated chromatin requires a feature in its histone-fold domain, distinguishing this process from incorporation into H3K27me3-containing chromatin in which multiple features of macroH2A1 are sufficient for targeting. In addition, we identify H2BK20 acetylation as a critical modification required to target macroH2A1 to H2B-acetylated chromatin. Our findings have allowed us to definitively establish that macroH2A1's regulation of an important transcriptional program, the senescence-associated secretory phenotype (SASP), requires its accurate genomic localization.
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47
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Galupa R, Heard E. X-Chromosome Inactivation: A Crossroads Between Chromosome Architecture and Gene Regulation. Annu Rev Genet 2018; 52:535-566. [PMID: 30256677 DOI: 10.1146/annurev-genet-120116-024611] [Citation(s) in RCA: 144] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
In somatic nuclei of female therian mammals, the two X chromosomes display very different chromatin states: One X is typically euchromatic and transcriptionally active, and the other is mostly silent and forms a cytologically detectable heterochromatic structure termed the Barr body. These differences, which arise during female development as a result of X-chromosome inactivation (XCI), have been the focus of research for many decades. Initial approaches to define the structure of the inactive X chromosome (Xi) and its relationship to gene expression mainly involved microscopy-based approaches. More recently, with the advent of genomic techniques such as chromosome conformation capture, molecular details of the structure and expression of the Xi have been revealed. Here, we review our current knowledge of the 3D organization of the mammalian X-chromosome chromatin and discuss its relationship with gene activity in light of the initiation, spreading, and maintenance of XCI, as well as escape from gene silencing.
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Affiliation(s)
- Rafael Galupa
- Genetics and Developmental Biology Unit and Mammalian Developmental Epigenetics Group, Institut Curie, PSL Research University, CNRS UMR3215, INSERM U934, 75248 Paris, France; .,Current affiliation: Developmental Biology Unit, European Molecular Biology Laboratory, 69117 Heidelberg, Germany
| | - Edith Heard
- Genetics and Developmental Biology Unit and Mammalian Developmental Epigenetics Group, Institut Curie, PSL Research University, CNRS UMR3215, INSERM U934, 75248 Paris, France; .,Collège de France, 75231 Paris, France
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48
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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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49
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Xing F, Liu Y, Wu SY, Wu K, Sharma S, Mo YY, Feng J, Sanders S, Jin G, Singh R, Vidi PA, Tyagi A, Chan MD, Ruiz J, Debinski W, Pasche BC, Lo HW, Metheny-Barlow LJ, D'Agostino RB, Watabe K. Loss of XIST in Breast Cancer Activates MSN-c-Met and Reprograms Microglia via Exosomal miRNA to Promote Brain Metastasis. Cancer Res 2018; 78:4316-4330. [PMID: 30026327 PMCID: PMC6072593 DOI: 10.1158/0008-5472.can-18-1102] [Citation(s) in RCA: 213] [Impact Index Per Article: 35.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Revised: 05/25/2018] [Accepted: 06/05/2018] [Indexed: 12/15/2022]
Abstract
Up to 30% of patients with metastatic breast cancer eventually develop brain metastasis, yet the pathologic mechanism behind this development remains poorly understood. Here, we profiled long noncoding RNAs in brain metastatic tumors from patients with breast cancer and found that the X-inactive-specific transcript (XIST) was significantly downregulated in these tissues. XIST expression levels inversely correlated with brain metastasis, but not with bone metastasis in patients. Silencing of XIST preferentially promoted brain metastatic growth of XISThigh cells in our xenograft models. Moreover, knockout of XIST in mice mammary glands accelerated primary tumor growth as well as metastases in the brain. Decreased expression of XIST stimulated epithelial-mesenchymal transition and activated c-Met via MSN-mediated protein stabilization, which resulted in the promotion of stemness in the tumor cells. Loss of XIST also augmented secretion of exosomal miRNA-503, which triggered M1-M2 polarization of microglia. This M1-M2 conversion upregulated immune suppressive cytokines in microglia that suppressed T-cell proliferation. Furthermore, we screened an FDA-approved drug library and identified fludarabine as a synthetic lethal drug for XISTlow breast tumor cells and found that fludarabine blocked brain metastasis in our animal model. Our results indicate that XIST plays a critical role in brain metastasis in breast cancer by affecting both tumor cells and the tumor microenvironment and that the XIST-mediated pathway may serve as an effective target for treating brain metastasis.Significance: These findings describe mechanisms of how loss of the lncRNA XIST promotes brain metastasis in breast cancer and identify fludarabine as a potential therapeutic agent that specifically eliminates XISTlow tumor cells in the brain. Cancer Res; 78(15); 4316-30. ©2018 AACR.
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Affiliation(s)
- Fei Xing
- Department of Cancer Biology, Wake Forest School of Medicine, Winston Salem, North Carolina.
| | - Yin Liu
- Department of Cancer Biology, Wake Forest School of Medicine, Winston Salem, North Carolina
| | - Shih-Ying Wu
- Department of Cancer Biology, Wake Forest School of Medicine, Winston Salem, North Carolina
| | - Kerui Wu
- Department of Cancer Biology, Wake Forest School of Medicine, Winston Salem, North Carolina
| | - Sambad Sharma
- Department of Cancer Biology, Wake Forest School of Medicine, Winston Salem, North Carolina
| | - Yin-Yuan Mo
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson, Mississippi
| | - Jiamei Feng
- Mammary Department, Shuguang Hospital affiliated to Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Stephanie Sanders
- Department of Cancer Biology, Wake Forest School of Medicine, Winston Salem, North Carolina
| | - Guangxu Jin
- Department of Cancer Biology, Wake Forest School of Medicine, Winston Salem, North Carolina
| | - Ravi Singh
- Department of Cancer Biology, Wake Forest School of Medicine, Winston Salem, North Carolina
| | - Pierre-Alexandre Vidi
- Department of Cancer Biology, Wake Forest School of Medicine, Winston Salem, North Carolina
| | - Abhishek Tyagi
- Department of Cancer Biology, Wake Forest School of Medicine, Winston Salem, North Carolina
| | - Michael D Chan
- Department of Radiation Oncology, Wake Forest School of Medicine, Winston Salem, North Carolina
| | - Jimmy Ruiz
- Department of Hematology & Oncology, Wake Forest School of Medicine, Winston Salem, North Carolina
| | - Waldemar Debinski
- Department of Cancer Biology, Wake Forest School of Medicine, Winston Salem, North Carolina
| | - Boris C Pasche
- Department of Cancer Biology, Wake Forest School of Medicine, Winston Salem, North Carolina
| | - Hui-Wen Lo
- Department of Cancer Biology, Wake Forest School of Medicine, Winston Salem, North Carolina
| | - Linda J Metheny-Barlow
- Department of Cancer Biology, Wake Forest School of Medicine, Winston Salem, North Carolina
| | - Ralph B D'Agostino
- Biostatistical Sciences Institute for Regenerative Medicine, Wake Forest School of Medicine, Winston Salem, NC
| | - Kounosuke Watabe
- Department of Cancer Biology, Wake Forest School of Medicine, Winston Salem, North Carolina.
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50
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Sahakyan A, Yang Y, Plath K. The Role of Xist in X-Chromosome Dosage Compensation. Trends Cell Biol 2018; 28:999-1013. [PMID: 29910081 DOI: 10.1016/j.tcb.2018.05.005] [Citation(s) in RCA: 91] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Revised: 05/16/2018] [Accepted: 05/22/2018] [Indexed: 01/15/2023]
Abstract
In each somatic cell of a female mammal one X chromosome is transcriptionally silenced via X-chromosome inactivation (XCI), initiating early in development. Although XCI events are conserved in mouse and human postimplantation development, regulation of X-chromosome dosage in preimplantation development occurs differently. In preimplantation development, mouse embryos undergo imprinted form of XCI, yet humans lack imprinted XCI and instead regulate gene expression of both X chromosomes by dampening transcription. The long non-coding RNA Xist/XIST is expressed in mouse and human preimplantation and postimplantation development to orchestrate XCI, but its role in dampening is unclear. In this review, we discuss recent advances in our understanding of the role of Xist in X chromosome dosage compensation in mouse and human.
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Affiliation(s)
- Anna Sahakyan
- David Geffen School of Medicine, Department of Biological Chemistry, Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, Jonsson Comprehensive Cancer Center, Molecular Biology Institute, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Yihao Yang
- David Geffen School of Medicine, Department of Biological Chemistry, Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, Jonsson Comprehensive Cancer Center, Molecular Biology Institute, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Kathrin Plath
- David Geffen School of Medicine, Department of Biological Chemistry, Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, Jonsson Comprehensive Cancer Center, Molecular Biology Institute, University of California Los Angeles, Los Angeles, CA 90095, USA.
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