1
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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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2
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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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3
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X-chromosome reactivation: a concise review. Biochem Soc Trans 2021; 49:2797-2805. [PMID: 34821360 DOI: 10.1042/bst20210777] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Revised: 11/03/2021] [Accepted: 11/05/2021] [Indexed: 12/14/2022]
Abstract
Mammalian females (XX) silence transcription on one of the two X chromosomes to compensate the expression dosage with males (XY). This process - named X-chromosome inactivation - entails a variety of epigenetic modifications that act synergistically to maintain silencing and make it heritable through cell divisions. Genes along the inactive X chromosome are, indeed, refractory to reactivation. Nonetheless, X-chromosome reactivation can occur alongside with epigenome reprogramming or by perturbing multiple silencing pathways. Here we review the events associated with X-chromosome reactivation during in vivo and in vitro reprogramming and highlight recent efforts in inducing Xi reactivation by molecular perturbations. This provides us with a first understanding of the mechanisms underlying X-chromosome reactivation, which could be tackled for therapeutic purposes.
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4
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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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5
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Song Z, Lin J, Li Z, Huang C. The nuclear functions of long noncoding RNAs come into focus. Noncoding RNA Res 2021; 6:70-79. [PMID: 33898883 PMCID: PMC8053782 DOI: 10.1016/j.ncrna.2021.03.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Revised: 03/18/2021] [Accepted: 03/22/2021] [Indexed: 12/16/2022] Open
Abstract
Long noncoding RNAs (lncRNAs), defined as untranslated and tightly-regulated transcripts with a length exceeding 200 nt, are common outputs of the eukaryotic genome. It is becoming increasingly apparent that many lncRNAs likely serve as important regulators in a variety of biological processes. In particular, some of them accumulate in the nucleus and function in diverse nuclear events, including chromatin remodeling, transcriptional regulation, RNA processing, DNA damage repair, etc. Here, we unite recent progresses on the functions of nuclear lncRNAs and provide insights into the future research directions of this field.
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Affiliation(s)
- Zhenxing Song
- School of Life Sciences, Chongqing University, Chongqing, 401331, China
- Center of Plant Functional Genomics, Institute of Advanced Interdisciplinary Studies, Chongqing University, Chongqing, 401331, China
| | - Jiamei Lin
- School of Life Sciences, Chongqing University, Chongqing, 401331, China
- Center of Plant Functional Genomics, Institute of Advanced Interdisciplinary Studies, Chongqing University, Chongqing, 401331, China
| | - Zhengguo Li
- School of Life Sciences, Chongqing University, Chongqing, 401331, China
- Center of Plant Functional Genomics, Institute of Advanced Interdisciplinary Studies, Chongqing University, Chongqing, 401331, China
| | - Chuan Huang
- School of Life Sciences, Chongqing University, Chongqing, 401331, China
- Center of Plant Functional Genomics, Institute of Advanced Interdisciplinary Studies, Chongqing University, Chongqing, 401331, China
- Corresponding author. School of Life Sciences, Chongqing University, Chongqing, 401331, China.
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Sas-Nowosielska H, Magalska A. Long Noncoding RNAs-Crucial Players Organizing the Landscape of the Neuronal Nucleus. Int J Mol Sci 2021; 22:ijms22073478. [PMID: 33801737 PMCID: PMC8037058 DOI: 10.3390/ijms22073478] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Revised: 03/22/2021] [Accepted: 03/24/2021] [Indexed: 12/25/2022] Open
Abstract
The ability to regulate chromatin organization is particularly important in neurons, which dynamically respond to external stimuli. Accumulating evidence shows that lncRNAs play important architectural roles in organizing different nuclear domains like inactive chromosome X, splicing speckles, paraspeckles, and Gomafu nuclear bodies. LncRNAs are abundantly expressed in the nervous system where they may play important roles in compartmentalization of the cell nucleus. In this review we will describe the architectural role of lncRNAs in the nuclei of neuronal cells.
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7
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Abstract
The subcellular localization of RNAs correlates with their function and how they are regulated. Most protein-coding mRNAs are exported into the cytoplasm for protein synthesis, while some mRNA species, long noncoding RNAs, and some regulatory element-associated unstable transcripts tend to be retained in the nucleus, where they function as a regulatory unit and/or are regulated by nuclear surveillance pathways. While the mechanisms regulating mRNA export and localization have been well summarized, the mechanisms governing nuclear retention of RNAs, especially of noncoding RNAs, are seldomly reviewed. In this review, we summarize recent advances in the mechanistic study of RNA nuclear retention, especially for noncoding RNAs, from the angle of cis-acting elements embedded in RNA transcripts and their interaction with trans-acting factors. We also try to illustrate the general principles of RNA nuclear retention and we discuss potential areas for future investigation.
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Affiliation(s)
- Chong Tong
- Department of Cell Biology and Department of Cardiology of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Yafei Yin
- Department of Cell Biology and Department of Cardiology of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
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8
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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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9
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Xu Y, Li Z. CRISPR-Cas systems: Overview, innovations and applications in human disease research and gene therapy. Comput Struct Biotechnol J 2020; 18:2401-2415. [PMID: 33005303 PMCID: PMC7508700 DOI: 10.1016/j.csbj.2020.08.031] [Citation(s) in RCA: 89] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Revised: 08/31/2020] [Accepted: 08/31/2020] [Indexed: 02/08/2023] Open
Abstract
Genome editing is the modification of genomic DNA at a specific target site in a wide variety of cell types and organisms, including insertion, deletion and replacement of DNA, resulting in inactivation of target genes, acquisition of novel genetic traits and correction of pathogenic gene mutations. Due to the advantages of simple design, low cost, high efficiency, good repeatability and short-cycle, CRISPR-Cas systems have become the most widely used genome editing technology in molecular biology laboratories all around the world. In this review, an overview of the CRISPR-Cas systems will be introduced, including the innovations, the applications in human disease research and gene therapy, as well as the challenges and opportunities that will be faced in the practical application of CRISPR-Cas systems.
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Affiliation(s)
- Yuanyuan Xu
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Animal Science, Jilin University, Changchun 130062, China
| | - Zhanjun Li
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Animal Science, Jilin University, Changchun 130062, China
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10
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Patrat C, Ouimette JF, Rougeulle C. X chromosome inactivation in human development. Development 2020; 147:147/1/dev183095. [PMID: 31900287 DOI: 10.1242/dev.183095] [Citation(s) in RCA: 74] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
X chromosome inactivation (XCI) is a key developmental process taking place in female mammals to compensate for the imbalance in the dosage of X-chromosomal genes between sexes. It is a formidable example of concerted gene regulation and a paradigm for epigenetic processes. Although XCI has been substantially deciphered in the mouse model, how this process is initiated in humans has long remained unexplored. However, recent advances in the experimental capacity to access human embryonic-derived material and in the laws governing ethical considerations of human embryonic research have allowed us to enlighten this black box. Here, we will summarize the current knowledge of human XCI, mainly based on the analyses of embryos derived from in vitro fertilization and of pluripotent stem cells, and highlight any unanswered questions.
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Affiliation(s)
- Catherine Patrat
- Université de Paris, UMR 1016, Institut Cochin, 75014 Paris, France .,Service de Biologie de la Reproduction - CECOS, Paris Centre Hospital, APHP.centre, 75014 Paris, France
| | | | - Claire Rougeulle
- Université de Paris, Epigenetics and Cell Fate, CNRS, F-75013 Paris, France
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11
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Bousard A, Raposo AC, Żylicz JJ, Picard C, Pires VB, Qi Y, Gil C, Syx L, Chang HY, Heard E, da Rocha ST. The role of Xist-mediated Polycomb recruitment in the initiation of X-chromosome inactivation. EMBO Rep 2019; 20:e48019. [PMID: 31456285 PMCID: PMC6776897 DOI: 10.15252/embr.201948019] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Revised: 07/29/2019] [Accepted: 08/06/2019] [Indexed: 12/22/2022] Open
Abstract
Xist RNA has been established as the master regulator of X-chromosome inactivation (XCI) in female eutherian mammals, but its mechanism of action remains unclear. By creating novel Xist-inducible mutants at the endogenous locus in male mouse embryonic stem (ES) cells, we dissect the role of the conserved A-B-C-F repeats in the initiation of XCI. We find that transcriptional silencing can be largely uncoupled from Polycomb repressive complex 1 and complex 2 (PRC1/2) recruitment, which requires B and C repeats. Xist ΔB+C RNA specifically loses interaction with PCGF3/5 subunits of PRC1, while binding of other Xist partners is largely unaffected. However, a slight relaxation of transcriptional silencing in Xist ΔB+C indicates a role for PRC1/2 proteins in early stabilization of gene repression. Distinct modules within the Xist RNA are therefore involved in the convergence of independent chromatin modification and gene repression pathways. In this context, Polycomb recruitment seems to be of moderate relevance in the initiation of silencing.
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Affiliation(s)
- Aurélie Bousard
- Mammalian Developmental Epigenetics GroupInstitut CurieCNRS UMR3215, INSERM U934PSL UniversityParisFrance
| | - Ana Cláudia Raposo
- Instituto de Medicina MolecularJoão Lobo AntunesFaculdade de MedicinaUniversidade de LisboaLisboaPortugal
| | - Jan Jakub Żylicz
- Mammalian Developmental Epigenetics GroupInstitut CurieCNRS UMR3215, INSERM U934PSL UniversityParisFrance
- Department of Physiology, Development and NeuroscienceUniversity of CambridgeCambridgeUK
| | - Christel Picard
- Mammalian Developmental Epigenetics GroupInstitut CurieCNRS UMR3215, INSERM U934PSL UniversityParisFrance
| | - Vanessa Borges Pires
- Instituto de Medicina MolecularJoão Lobo AntunesFaculdade de MedicinaUniversidade de LisboaLisboaPortugal
- Instituto de Ciências Biomédicas Abel SalazarUniversidade do PortoPortoPortugal
| | - Yanyan Qi
- Center for Dynamic Personal RegulomesStanford UniversityStanfordCAUSA
| | - Cláudia Gil
- Instituto de Medicina MolecularJoão Lobo AntunesFaculdade de MedicinaUniversidade de LisboaLisboaPortugal
| | - Laurène Syx
- Mammalian Developmental Epigenetics GroupInstitut CurieCNRS UMR3215, INSERM U934PSL UniversityParisFrance
| | - Howard Y Chang
- Center for Dynamic Personal RegulomesStanford UniversityStanfordCAUSA
- Howard Hughes Medical InstituteStanford UniversityStanfordCAUSA
| | - Edith Heard
- Mammalian Developmental Epigenetics GroupInstitut CurieCNRS UMR3215, INSERM U934PSL UniversityParisFrance
| | - Simão Teixeira da Rocha
- Mammalian Developmental Epigenetics GroupInstitut CurieCNRS UMR3215, INSERM U934PSL UniversityParisFrance
- Instituto de Medicina MolecularJoão Lobo AntunesFaculdade de MedicinaUniversidade de LisboaLisboaPortugal
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12
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Lee HJ, Gopalappa R, Sunwoo H, Choi SW, Ramakrishna S, Lee JT, Kim HH, Nam JW. En bloc and segmental deletions of human XIST reveal X chromosome inactivation-involving RNA elements. Nucleic Acids Res 2019; 47:3875-3887. [PMID: 30783652 PMCID: PMC6486550 DOI: 10.1093/nar/gkz109] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Revised: 02/07/2019] [Accepted: 02/13/2019] [Indexed: 12/13/2022] Open
Abstract
The XIST RNA is a non-coding RNA that induces X chromosome inactivation (XCI). Unlike the mouse Xist RNA, how the human XIST RNA controls XCI in female cells is less well characterized, and its functional motifs remain unclear. To systematically decipher the XCI-involving elements of XIST RNA, 11 smaller XIST segments, including repeats A, D and E; human-specific repeat elements; the promoter; and non-repetitive exons, as well as the entire XIST gene, were homozygously deleted in K562 cells using the Cas9 nuclease and paired guide RNAs at high efficiencies, followed by high-throughput RNA sequencing and RNA fluorescence in situ hybridization experiments. Clones containing en bloc and promoter deletions that consistently displayed no XIST RNAs and a global up-regulation of X-linked genes confirmed that the deletion of XIST reactivates the inactive X chromosome. Systematic analyses of segmental deletions delineated that exon 5 harboring the non-repeat element is important for X-inactivation maintenance, whereas exons 2, 3 and 4 as well as the other repeats in exon 1 are less important, a different situation from that of mouse Xist. This Cas9-assisted dissection of XIST allowed us to understand the unique functional domains within the human XIST RNA.
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MESH Headings
- Alternative Splicing
- Animals
- Base Sequence
- CRISPR-Associated Protein 9/genetics
- CRISPR-Associated Protein 9/metabolism
- CRISPR-Cas Systems
- Chromosomes, Human, X/chemistry
- Chromosomes, Human, X/metabolism
- Clone Cells
- Exons
- Gene Editing/methods
- Genome, Human
- Humans
- K562 Cells
- Mice
- Promoter Regions, Genetic
- RNA, Long Noncoding/genetics
- RNA, Long Noncoding/metabolism
- Sequence Deletion
- Species Specificity
- Whole Genome Sequencing
- X Chromosome Inactivation
- RNA, Guide, CRISPR-Cas Systems
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Affiliation(s)
- Hyeon J Lee
- Department of Life Science, College of Natural Sciences, Hanyang University, Seoul 04763, Republic of Korea
| | - Ramu Gopalappa
- Department of Pharmacology, Yonsei University College of Medicine, Seoul 03722, Republic of Korea
| | - Hongjae Sunwoo
- Department of Molecular Biology, Massachusetts General Hospital, Department of Genetics, Harvard Medical School, Boston MA 02114, USA
| | - Seo-Won Choi
- Department of Life Science, College of Natural Sciences, Hanyang University, Seoul 04763, Republic of Korea
| | - Suresh Ramakrishna
- Graduate School of Biomedical Science and Engineering, Hanyang University, Seoul 04763, Republic of Korea
- College of Medicine, Hanyang University, Seoul 04763, Republic of Korea
| | - Jeannie T Lee
- Department of Molecular Biology, Massachusetts General Hospital, Department of Genetics, Harvard Medical School, Boston MA 02114, USA
| | - Hyongbum H Kim
- Department of Pharmacology, Yonsei University College of Medicine, Seoul 03722, Republic of Korea
- Brain Korea 21 Plus Project for Medical Sciences, Yonsei University College of Medicine, Seoul 03722, Republic of Korea
- Severance Biomedical Science Institute, Yonsei University College of Medicine, Seoul 03722, Republic of Korea
- Center for Nanomedicine, Institute for Basic Science (IBS), Seoul 34126, Republic of Korea
| | - Jin-Wu Nam
- Department of Life Science, College of Natural Sciences, Hanyang University, Seoul 04763, Republic of Korea
- Research Institute for Convergence of Basic Sciences, Hanyang University, Seoul 04763, Republic of Korea
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13
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Monfort A, Wutz A. Progress in understanding the molecular mechanism of Xist RNA function through genetics. Philos Trans R Soc Lond B Biol Sci 2018; 372:rstb.2016.0368. [PMID: 28947663 DOI: 10.1098/rstb.2016.0368] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/09/2017] [Indexed: 01/06/2023] Open
Abstract
The Xist gene produces a long noncoding RNA that initiates chromosome-wide gene repression on the inactive X chromosome in female mammals. Recent progress has advanced the understanding of Xist function at the molecular level. This review provides an overview of insights from genetic approaches and puts the new data in the context of an emerging mechanistic model as well as the existing literature. Some consideration is given on how independent biochemical studies on X inactivation help to advance on the wider question of chromatin regulation in the mammalian dosage compensation system.This article is part of the themed issue 'X-chromosome inactivation: a tribute to Mary Lyon'.
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Affiliation(s)
- Asun Monfort
- Institute of Molecular Health Sciences, Department of Biology, Swiss Federal Institute of Technology, ETH Hönggerberg, Otto-Stern-Weg 7, 8049 Zurich, Switzerland
| | - Anton Wutz
- Institute of Molecular Health Sciences, Department of Biology, Swiss Federal Institute of Technology, ETH Hönggerberg, Otto-Stern-Weg 7, 8049 Zurich, Switzerland
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14
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Ma W, Wang H, Jing W, Zhou F, Chang L, Hong Z, Liu H, Liu Z, Yuan Y. Downregulation of long non-coding RNAs JPX and XIST is associated with the prognosis of hepatocellular carcinoma. Clin Res Hepatol Gastroenterol 2017; 41:163-170. [PMID: 27776968 DOI: 10.1016/j.clinre.2016.09.002] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Revised: 08/18/2016] [Accepted: 09/02/2016] [Indexed: 02/04/2023]
Abstract
BACKGROUND The expression profiles and biological relevance of long non-coding RNA XIST and its activator JPX in hepatocellular carcinoma (HCC) are not well elucidated. We measured JPX and XIST expression levels in HCC, evaluated their clinical significance in HCC progression, and verified their potential as biomarkers for diagnosing HCC. METHODS JPX and XIST expression in 68 HCC tissues and adjacent normal tissues were evaluated by quantitative reverse transcription-PCR (qRT-PCR); their association with pathologic features and overall survival was analyzed. Plasma JPX/XIST levels in 42 patients with HCC and 68 healthy controls were measured by qRT-PCR to determine their potential as biomarkers. RESULTS JPX and XIST levels were significantly decreased in HCC and associated with histological grade and tumor-node-metastasis stage (P<0.05). Low JPX and XIST expression resulted in significantly poor overall survival of HCC. Multivariate Cox regression analysis demonstrated that JPX/XIST expression levels were independent prognostic factors for HCC overall survival rates. Moreover, plasma JPX levels in patients were lower than that in controls; JPX yielded an area under the receiver operating characteristic curve of 0.814 and the combination of JPX and AFP possessed a promoted ability for discrimination between HCC patients and controls (AUC 0.905, 72.2% specificity, 97.1% sensitivity). CONCLUSIONS Downregulated JPX and XIST may serve as novel biomarkers of poor prognosis in HCC.
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Affiliation(s)
- Weijie Ma
- Department of Hepatobiliary and Pancreatic Surgery, Zhongnan Hospital of Wuhan University, Donghu Road 169#, Wuhan 430071, China
| | - Haitao Wang
- Department of Hepatobiliary and Pancreatic Surgery, Zhongnan Hospital of Wuhan University, Donghu Road 169#, Wuhan 430071, China
| | - Wei Jing
- Department of Clinical Laboratory Medicine and Center for Gene Diagnosis, Zhongnan Hospital of Wuhan University, Wuhan, China
| | - Fuling Zhou
- Department of Clinical Hematology, Zhongnan Hospital of Wuhan University, Wuhan, China
| | - Lei Chang
- Department of Hepatobiliary and Pancreatic Surgery, Zhongnan Hospital of Wuhan University, Donghu Road 169#, Wuhan 430071, China
| | - Zhenfei Hong
- Department of Hepatobiliary and Pancreatic Surgery, Zhongnan Hospital of Wuhan University, Donghu Road 169#, Wuhan 430071, China
| | - Hailing Liu
- Department of Clinical Hematology, Second Affiliated Hospital, Medical School of Xi'an Jiaotong University, Xi'an 710004, China
| | - Zhisu Liu
- Department of Hepatobiliary and Pancreatic Surgery, Zhongnan Hospital of Wuhan University, Donghu Road 169#, Wuhan 430071, China
| | - Yufeng Yuan
- Department of Hepatobiliary and Pancreatic Surgery, Zhongnan Hospital of Wuhan University, Donghu Road 169#, Wuhan 430071, China.
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15
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Li R, Zhu H, Luo Y. Understanding the Functions of Long Non-Coding RNAs through Their Higher-Order Structures. Int J Mol Sci 2016; 17:ijms17050702. [PMID: 27196897 PMCID: PMC4881525 DOI: 10.3390/ijms17050702] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2016] [Revised: 04/28/2016] [Accepted: 05/04/2016] [Indexed: 02/08/2023] Open
Abstract
Although thousands of long non-coding RNAs (lncRNAs) have been discovered in eukaryotes, very few molecular mechanisms have been characterized due to an insufficient understanding of lncRNA structure. Therefore, investigations of lncRNA structure and subsequent elucidation of the regulatory mechanisms are urgently needed. However, since lncRNA are high molecular weight molecules, which makes their crystallization difficult, obtaining information about their structure is extremely challenging, and the structures of only several lncRNAs have been determined so far. Here, we review the structure-function relationships of the widely studied lncRNAs found in the animal and plant kingdoms, focusing on the principles and applications of both in vitro and in vivo technologies for the study of RNA structures, including dimethyl sulfate-sequencing (DMS-seq), selective 2'-hydroxyl acylation analyzed by primer extension-sequencing (SHAPE-seq), parallel analysis of RNA structure (PARS), and fragmentation sequencing (FragSeq). The aim of this review is to provide a better understanding of lncRNA biological functions by studying them at the structural level.
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Affiliation(s)
- Rui Li
- Department of Food Biotechnology, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China.
| | - Hongliang Zhu
- Department of Food Biotechnology, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China.
| | - Yunbo Luo
- Department of Food Biotechnology, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China.
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Pinter SF. A Tale of Two Cities: How Xist and its partners localize to and silence the bicompartmental X. Semin Cell Dev Biol 2016; 56:19-34. [PMID: 27072488 DOI: 10.1016/j.semcdb.2016.03.023] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2016] [Revised: 03/30/2016] [Accepted: 03/30/2016] [Indexed: 10/22/2022]
Abstract
Sex chromosomal dosage compensation in mammals takes the form of X chromosome inactivation (XCI), driven by the non-coding RNA Xist. In contrast to dosage compensation systems of flies and worms, mammalian XCI has to restrict its function to the Xist-producing X chromosome, while leaving autosomes and active X untouched. The mechanisms behind the long-range yet cis-specific localization and silencing activities of Xist have long been enigmatic, but genomics, proteomics, super-resolution microscopy, and innovative genetic approaches have produced significant new insights in recent years. In this review, I summarize and integrate these findings with a particular focus on the redundant yet mutually reinforcing pathways that enable long-term transcriptional repression throughout the soma. This includes an exploration of concurrent epigenetic changes acting in parallel within two distinct compartments of the inactive X. I also examine how Polycomb repressive complexes 1 and 2 and macroH2A may bridge XCI establishment and maintenance. XCI is a remarkable phenomenon that operates across multiple scales, combining changes in nuclear architecture, chromosome topology, chromatin compaction, and nucleosome/nucleotide-level epigenetic cues. Learning how these pathways act in concert likely holds the answer to the riddle posed by Cattanach's and other autosomal translocations: What makes the X especially receptive to XCI?
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Affiliation(s)
- Stefan F Pinter
- Department of Genetics and Genome Sciences, Institute for Systems Genomics, University of Connecticut Health Center, 263 Farmington Ave, Farmington, CT 06030-6403, USA.
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