101
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Tomita S, Abdalla MOA, Fujiwara S, Yamamoto T, Iwase H, Nakao M, Saitoh N. Roles of long noncoding RNAs in chromosome domains. WILEY INTERDISCIPLINARY REVIEWS-RNA 2016; 8. [DOI: 10.1002/wrna.1384] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2016] [Revised: 06/30/2016] [Accepted: 07/07/2016] [Indexed: 12/26/2022]
Affiliation(s)
- Saori Tomita
- Department of Medical Cell Biology, Institute of Molecular Embryology and Genetics; Kumamoto University; Kumamoto Japan
- Department of Breast and Endocrine Surgery, Graduate School of Medical Sciences; Kumamoto University; Kumamoto Japan
| | - Mohamed Osama Ali Abdalla
- Department of Medical Cell Biology, Institute of Molecular Embryology and Genetics; Kumamoto University; Kumamoto Japan
- Department of Clinical Pathology, Faculty of Medicine; Suez Canal University; Ismailia Egypt
| | - Saori Fujiwara
- Department of Medical Cell Biology, Institute of Molecular Embryology and Genetics; Kumamoto University; Kumamoto Japan
- Department of Breast and Endocrine Surgery, Graduate School of Medical Sciences; Kumamoto University; Kumamoto Japan
| | - Tatsuro Yamamoto
- Department of Medical Cell Biology, Institute of Molecular Embryology and Genetics; Kumamoto University; Kumamoto Japan
| | - Hirotaka Iwase
- Department of Breast and Endocrine Surgery, Graduate School of Medical Sciences; Kumamoto University; Kumamoto Japan
| | - Mitsuyoshi Nakao
- Department of Medical Cell Biology, Institute of Molecular Embryology and Genetics; Kumamoto University; Kumamoto Japan
- Core Research for Evolutional Science and Technology (CREST), Japan Agency for Medical Research and Development; Tokyo Japan
| | - Noriko Saitoh
- Department of Medical Cell Biology, Institute of Molecular Embryology and Genetics; Kumamoto University; Kumamoto Japan
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102
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Nguyen Q, Carninci P. Expression Specificity of Disease-Associated lncRNAs: Toward Personalized Medicine. Curr Top Microbiol Immunol 2016; 394:237-58. [PMID: 26318140 DOI: 10.1007/82_2015_464] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Long noncoding RNAs (lncRNAs) perform diverse regulatory functions in transcription, translation' chromatin modification, and cellular organization. Misregulation of lncRNAs is found linked to various human diseases. Compared to protein-coding RNAs' lncRNAs are more specific to organs, tissues, cell types, developmental stages, and disease conditions' making them promising candidates as diagnostic and prognostic biomarkers and as gene therapy targets. The functional annotation of mammalian genome (FANTOM) consortium utilizes cap analysis of gene expression (CAGE) method to quantify genome-wide activities of promoters and enhancers of coding and noncoding RNAs across a large collection of human and mouse tissues' cell types' diseases, and time-courses. The project discovered widespread transcription of major lncRNA classes, including lncRNAs derived from enhancers' bidirectional promoters' antisense lncRNAs' and repetitive elements. Results from FANTOM project enable assessment of lncRNA expression specificity across tissue and disease conditions' based on differential promoter and enhancer usage. More than 85 % of disease-related SNPs are within noncoding regions and are strikingly overrepresented in enhancer and promoter regions, suggestive of the importance of lncRNA loci at these SNP harboring regions to human diseases. In this chapter' we discuss lncRNA expression specificity' review diverse functions of disease-associated lncRNAs' and present perspectives on their potential therapeutic applications for personalized medicine. The future development of lncRNA applications relies on technologies to identify and validate their functions' structures' and mechanisms. Comprehensive understanding of genome-wide interaction networks of lncRNAs with proteins, chromatins, and other RNAs in regulating cellular processes will allow personalized medicine to use lncRNAs as highly specific biomarkers in diagnosis' prognosis, and therapeutic targets.
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Affiliation(s)
- Quan Nguyen
- Division of Genomic Technologies, RIKEN Yokohama Campus, RIKEN Center for Life Science Technologies, 1-7-22 Suehiro-Cho, Tsurumi-Ku, Yokohama City, Kanagawa, 230-0045, Japan
| | - Piero Carninci
- Division of Genomic Technologies, RIKEN Yokohama Campus, RIKEN Center for Life Science Technologies, 1-7-22 Suehiro-Cho, Tsurumi-Ku, Yokohama City, Kanagawa, 230-0045, Japan.
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103
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Aranda-Anzaldo A, Dent MAR. Why Cortical Neurons Cannot Divide, and Why Do They Usually Die in the Attempt? J Neurosci Res 2016; 95:921-929. [PMID: 27402311 DOI: 10.1002/jnr.23765] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Revised: 03/25/2016] [Accepted: 04/25/2016] [Indexed: 12/19/2022]
Abstract
Cortical neurons are prime examples of terminally differentiated, postmitotic cells. However, under experimental or pathological conditions, they can re-enter the cell cycle and replicate DNA but are unable to divide, dying by apoptosis or becoming either polyploid or aneuploid. Any cellular state that depends on the action of genes and their products can be reverted or bypassed by spontaneous or induced mutations, yet there are currently no reports of dividing cortical neurons. Thus, it seems unlikely that the remarkably stable postmitotic condition of cortical neurons depends on specific gene functions. This Review summarizes evidence that the postmitotic state of cortical neurons depends on the high stability of its underlying nuclear structure that results from an entropy-driven process aimed at dissipating the intrinsic structural stress present in chromosomal DNA in such a way that the structural stability of the neuronal nucleus becomes an insurmountable energy barrier for karyokinesis and mitosis. From this perspective, the integral properties of the nuclear higher order structure in neurons provide an explanation not only for why cortical neurons cannot divide but also for why they usually die if they happen to replicate their DNA. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Armando Aranda-Anzaldo
- Laboratorio de Biología Molecular y Neurociencias, Facultad de Medicina, Universidad Autónoma del Estado de México, Toluca, Estado México, México
| | - Myrna A R Dent
- Laboratorio de Biología Molecular y Neurociencias, Facultad de Medicina, Universidad Autónoma del Estado de México, Toluca, Estado México, México
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104
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Abstract
Transcription termination is a fundamental process in which RNA polymerase ceases RNA chain extension and dissociates from the chromatin template, thereby defining the end of the transcription unit. Our understanding of the biological role and functional importance of termination by RNA polymerase II and the range of processes in which it is involved has grown significantly in recent years. A large set of nucleic acid-binding proteins and enzymes have been identified as part of the termination machinery. A greater appreciation for the coupling of termination to RNA processing and metabolism has been recognized. In addition to serving as an essential step at the end of the transcription cycle, termination is involved in the regulation of a broad range of cellular processes. More recently, a role for termination in pervasive transcription, non-coding RNA regulation, genetic stability, chromatin remodeling, the immune response, and disease has come to the fore. Interesting mechanistic questions remain, but the last several years have resulted in significant insights into termination and an increasing recognition of its biological importance.
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Affiliation(s)
- Travis J Loya
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA, 30322, USA
| | - Daniel Reines
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA, 30322, USA
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105
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Hall LL, Lawrence JB. RNA as a fundamental component of interphase chromosomes: could repeats prove key? Curr Opin Genet Dev 2016; 37:137-147. [PMID: 27218204 DOI: 10.1016/j.gde.2016.04.005] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2015] [Revised: 04/01/2016] [Accepted: 04/06/2016] [Indexed: 11/29/2022]
Abstract
Beginning with the precedent of XIST RNA as a 'chromosomal RNA' (cRNA), there is growing interest in the possibility that a diversity of non-coding RNAs may function in chromatin. We review findings which lead us to suggest that RNA is essentially a widespread component of interphase chromosomes. Further, RNA likely contributes to architecture and regulation, with repeat-rich 'junk' RNA in euchromatin (ecRNA) promoting a more open chromatin state. Thousands of low-abundance nuclear RNAs have been reported, however it remains a challenge to determine which of these may function in chromatin. Recent findings indicate that repetitive sequences are enriched in chromosome-associated non-coding RNAs, and repeat-rich RNA shows unusual properties, including localization and stability, with similarities to XIST RNA. We suggest two frontiers in genome biology are emerging and may intersect: the broad contribution of RNA to interphase chromosomes and the distinctive properties of repeat-rich intronic or intergenic junk sequences that may play a role in chromosome structure and regulation.
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Affiliation(s)
- Lisa L Hall
- Department of Cell & Developmental Biology, University of Massachusetts Medical School, 55 Lake Avenue North, Worcester, MA 01655, USA
| | - Jeanne B Lawrence
- Department of Cell & Developmental Biology, University of Massachusetts Medical School, 55 Lake Avenue North, Worcester, MA 01655, USA.
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106
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Casanova M, Liyakat Ali TM, Rougeulle C. Enlightening the contribution of the dark matter to the X chromosome inactivation process in mammals. Semin Cell Dev Biol 2016; 56:48-57. [PMID: 27174438 DOI: 10.1016/j.semcdb.2016.05.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Revised: 05/04/2016] [Accepted: 05/04/2016] [Indexed: 02/07/2023]
Abstract
X-chromosome inactivation (XCI) in mammals represents an exceptional example of transcriptional co-regulation occurring at the level of an entire chromosome. XCI is considered as a means to compensate for gene dosage imbalance between sexes, yet the largest part of the chromosome is composed of repeated elements of different nature and origins. Here we consider XCI from a repeat point of view, interrogating the mechanisms for inactivating X chromosome-derived repeated sequences and discussing the contribution of repetitive elements to the silencing process itself and to its evolution.
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Affiliation(s)
- Miguel Casanova
- Sorbonne Paris Cité, Epigenetics and Cell Fate, UMR 7216 CNRS, Université Paris Diderot, Paris, France
| | | | - Claire Rougeulle
- Sorbonne Paris Cité, Epigenetics and Cell Fate, UMR 7216 CNRS, Université Paris Diderot, Paris, France.
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107
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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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108
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Carvalho NDM, Carmo E, Neves RO, Schneider CH, Gross MC. Differential repetitive DNA composition in the centromeric region of chromosomes of Amazonian lizard species in the family Teiidae. COMPARATIVE CYTOGENETICS 2016; 10:203-217. [PMID: 27551343 PMCID: PMC4977797 DOI: 10.3897/compcytogen.v10i2.7081] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/04/2015] [Accepted: 02/18/2016] [Indexed: 06/06/2023]
Abstract
Differences in heterochromatin distribution patterns and its composition were observed in Amazonian teiid species. Studies have shown repetitive DNA harbors heterochromatic blocks which are located in centromeric and telomeric regions in Ameiva ameiva (Linnaeus, 1758), Kentropyx calcarata (Spix, 1825), Kentropyx pelviceps (Cope, 1868), and Tupinambis teguixin (Linnaeus, 1758). In Cnemidophorus sp.1, repetitive DNA has multiple signals along all chromosomes. The aim of this study was to characterize moderately and highly repetitive DNA sequences by C ot1-DNA from Ameiva ameiva and Cnemidophorus sp.1 genomes through cloning and DNA sequencing, as well as mapping them chromosomally to better understand its organization and genome dynamics. The results of sequencing of DNA libraries obtained by C ot1-DNA showed that different microsatellites, transposons, retrotransposons, and some gene families also comprise the fraction of repetitive DNA in the teiid species. FISH using C ot1-DNA probes isolated from both Ameiva ameiva and Cnemidophorus sp.1 showed these sequences mainly located in heterochromatic centromeric, and telomeric regions in Ameiva ameiva, Kentropyx calcarata, Kentropyx pelviceps, and Tupinambis teguixin chromosomes, indicating they play structural and functional roles in the genome of these species. In Cnemidophorus sp.1, C ot1-DNA probe isolated from Ameiva ameiva had multiple interstitial signals on chromosomes, whereas mapping of C ot1-DNA isolated from the Ameiva ameiva and Cnemidophorus sp.1 highlighted centromeric regions of some chromosomes. Thus, the data obtained showed that many repetitive DNA classes are part of the genome of Ameiva ameiva, Cnemidophorus sp.1, Kentroyx calcarata, Kentropyx pelviceps, and Tupinambis teguixin, and these sequences are shared among the analyzed teiid species, but they were not always allocated at the same chromosome position.
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Affiliation(s)
- Natalia D. M. Carvalho
- Laboratório de Citogenômica Animal, Universidade Federal do Amazonas, Instituto de Ciências Biológicas, Estrada do Contorno 3000, Aleixo, CEP 69077-000 - Manaus, AM – Brazil
| | - Edson Carmo
- Laboratório de Tecnologia de DNA, Universidade Federal do Amazonas, Instituto de Ciências Biológicas, Estrada do Contorno 3000, Aleixo, CEP 69077-000 - Manaus, AM – Brazil
| | - Rogerio O. Neves
- Laboratório de Tecnologia de DNA, Universidade Federal do Amazonas, Instituto de Ciências Biológicas, Estrada do Contorno 3000, Aleixo, CEP 69077-000 - Manaus, AM – Brazil
| | - Carlos Henrique Schneider
- Laboratório de Citogenômica Animal, Universidade Federal do Amazonas, Instituto de Ciências Biológicas, Estrada do Contorno 3000, Aleixo, CEP 69077-000 - Manaus, AM – Brazil
| | - Maria Claudia Gross
- Laboratório de Citogenômica Animal, Universidade Federal do Amazonas, Instituto de Ciências Biológicas, Estrada do Contorno 3000, Aleixo, CEP 69077-000 - Manaus, AM – Brazil
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109
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Pandya-Jones A, Plath K. The "lnc" between 3D chromatin structure and X chromosome inactivation. Semin Cell Dev Biol 2016; 56:35-47. [PMID: 27062886 DOI: 10.1016/j.semcdb.2016.04.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2016] [Revised: 04/01/2016] [Accepted: 04/04/2016] [Indexed: 12/01/2022]
Abstract
The long non-coding RNA Xist directs a remarkable instance of developmentally regulated, epigenetic change known as X Chromosome Inactivation (XCI). By spreading in cis across the X chromosome from which it is expressed, Xist RNA facilitates the creation of a heritably silent, heterochromatic nuclear territory that displays a three-dimensional structure distinct from that of the active X chromosome. How Xist RNA attaches to and propagates across a chromosome and its influence over the three-dimensional (3D) structure of the inactive X are aspects of XCI that have remained largely unclear. Here, we discuss studies that have made significant contributions towards answering these open questions.
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Affiliation(s)
- Amy Pandya-Jones
- Department of Biological Chemistry, Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, Jonsson Comprehensive Cancer Center, David Geffen School of Medicine at the University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Kathrin Plath
- Department of Biological Chemistry, Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, Jonsson Comprehensive Cancer Center, David Geffen School of Medicine at the University of California Los Angeles, Los Angeles, CA 90095, USA.
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110
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Meng Y, Yi X, Li X, Hu C, Wang J, Bai L, Czajkowsky DM, Shao Z. The non-coding RNA composition of the mitotic chromosome by 5'-tag sequencing. Nucleic Acids Res 2016; 44:4934-46. [PMID: 27016738 PMCID: PMC4889943 DOI: 10.1093/nar/gkw195] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Accepted: 03/15/2016] [Indexed: 12/16/2022] Open
Abstract
Mitotic chromosomes are one of the most commonly recognized sub-cellular structures in eukaryotic cells. Yet basic information necessary to understand their structure and assembly, such as their composition, is still lacking. Recent proteomic studies have begun to fill this void, identifying hundreds of RNA-binding proteins bound to mitotic chromosomes. However, by contrast, there are only two RNA species (U3 snRNA and rRNA) that are known to be associated with the mitotic chromosome, suggesting that there are many mitotic chromosome-associated RNAs (mCARs) not yet identified. Here, using a targeted protocol based on 5'-tag sequencing to profile the mammalian mCAR population, we report the identification of 1279 mCARs, the majority of which are ncRNAs, including lncRNAs that exhibit greater conservation across 60 vertebrate species than the entire population of lncRNAs. There is also a significant enrichment of snoRNAs and specific SINE RNAs. Finally, ∼40% of the mCARs are presently unannotated, many of which are as abundant as the annotated mCARs, suggesting that there are also many novel ncRNAs in the mCARs. Overall, the mCARs identified here, together with the previous proteomic and genomic data, constitute the first comprehensive catalogue of the molecular composition of the eukaryotic mitotic chromosomes.
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Affiliation(s)
- Yicong Meng
- Shanghai Center for Systems Biomedicine, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Xianfu Yi
- School of Biomedical Engineering, Tianjin Medical University, Tianjin 300070, China
| | - Xinhui Li
- Bio-ID Center, School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Chuansheng Hu
- Bio-ID Center, School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Ju Wang
- School of Biomedical Engineering, Tianjin Medical University, Tianjin 300070, China
| | - Ling Bai
- Bio-ID Center, School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Daniel M Czajkowsky
- Bio-ID Center, School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Zhifeng Shao
- Bio-ID Center, School of Biomedical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China State Key Laboratory of Oncogenes & Related Genes, Shanghai Jiao Tong University, Shanghai 200240, China
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111
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Abstract
The recognition of functional roles for transcribed long non-coding RNA (lncRNA) has provided a new dimension to our understanding of cellular physiology and disease pathogenesis. LncRNAs are a large group of structurally complex RNA genes that can interact with DNA, RNA, or protein molecules to modulate gene expression and to exert cellular effects through diverse mechanisms. The emerging knowledge regarding their functional roles and their aberrant expression in disease states emphasizes the potential for lncRNA to serve as targets for therapeutic intervention. In this concise review, we outline the mechanisms of action of lncRNAs, their functional cellular roles, and their involvement in disease. Using liver cancer as an example, we provide an overview of the emerging opportunities and potential approaches to target lncRNA-dependent mechanisms for therapeutic purposes.
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112
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Abstract
In recent years, the realization that most of the genome is transcribed has transformed the study of mammalian gene expression. Much effort has gone into investigating how this pervasive transcription is regulated and what the functions of the resulting transcripts are, if any. We recently discovered that stress-induced transcriptional readthrough generates very long downstream of gene containing transcripts (DoGs), which may explain up to 20% of intergenic transcription. DoGs are induced by osmotic stress at the level of transcription by a mechanism that depends on calcium release from the endoplasmic reticulum mediated by IP3 receptors. Here, we discuss DoG induction and function in the context of the literature, with special focus on 2 outstanding questions. First, we discuss possible molecular mechanisms underlying DoG induction through reduced transcription termination. Second, we explore how DoGs may function in maintaining euchromatin after nuclear scaffold stress. In short, we review important aspects of DoG biogenesis and function, and provide an outlook for continued DoG study.
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Affiliation(s)
- Anna Vilborg
- a Department of Molecular Biophysics and Biochemistry , Howard Hughes Medical Institute, University School of Medicine , New Haven , CT , USA.,b Boyer Center for Molecular Medicine , Yale University School of Medicine , New Haven , CT , USA
| | - Joan A Steitz
- a Department of Molecular Biophysics and Biochemistry , Howard Hughes Medical Institute, University School of Medicine , New Haven , CT , USA.,b Boyer Center for Molecular Medicine , Yale University School of Medicine , New Haven , CT , USA
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113
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Vilborg A, Passarelli MC, Steitz JA. Calcium signaling and transcription: elongation, DoGs, and eRNAs. ACTA ACUST UNITED AC 2016; 3. [PMID: 29147672 DOI: 10.14800/rci.1169] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The calcium ion (Ca2+) is a key intracellular signaling molecule with far-reaching effects on many cellular processes. One of the most important such Ca2+ regulated processes is transcription. A body of literature describes the effect of Ca2+ signaling on transcription initiation as occurring mainly through activation of gene-specific transcription factors by Ca2+-induced signaling cascades. However, the reach of Ca2+ extends far beyond the first step of transcription. In fact, Ca2+ can regulate all phases of transcription, with additional effects on transcription-associated events such as alternative splicing. Importantly, Ca2+ signaling mediates reduced transcription termination in response to certain stress conditions. This reduction allows readthrough transcription, generating a highly inducible and diverse class of downstream of gene containing transcripts (DoGs) that we have recently described.
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Affiliation(s)
- Anna Vilborg
- Department of Molecular Biophysics and Biochemistry, Howard Hughes Medical Institute Boyer Center for Molecular Medicine, Yale University School of Medicine, 295 Congress Avenue, New Haven, CT 06536, USA
| | - Maria C Passarelli
- Department of Molecular Biophysics and Biochemistry, Howard Hughes Medical Institute Boyer Center for Molecular Medicine, Yale University School of Medicine, 295 Congress Avenue, New Haven, CT 06536, USA
| | - Joan A Steitz
- Department of Molecular Biophysics and Biochemistry, Howard Hughes Medical Institute Boyer Center for Molecular Medicine, Yale University School of Medicine, 295 Congress Avenue, New Haven, CT 06536, USA
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114
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Coelho MB, Attig J, Ule J, Smith CWJ. Matrin3: connecting gene expression with the nuclear matrix. WILEY INTERDISCIPLINARY REVIEWS-RNA 2016; 7:303-15. [PMID: 26813864 DOI: 10.1002/wrna.1336] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2015] [Revised: 12/18/2015] [Accepted: 12/18/2015] [Indexed: 01/06/2023]
Abstract
As indicated by its name, Matrin3 was discovered as a component of the nuclear matrix, an insoluble fibrogranular network that structurally organizes the nucleus. Matrin3 possesses both DNA- and RNA-binding domains and, consistent with this, has been shown to function at a number of stages in the life cycle of messenger RNAs. These numerous activities indicate that Matrin3, and indeed the nuclear matrix, do not just provide a structural framework for nuclear activities but also play direct functional roles in these activities. Here, we review the structure, functions, and molecular interactions of Matrin3 and of Matrin3-related proteins, and the pathologies that can arise upon mutation of Matrin3. WIREs RNA 2016, 7:303-315. doi: 10.1002/wrna.1336 For further resources related to this article, please visit the WIREs website.
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Affiliation(s)
- Miguel B Coelho
- Department of Biochemistry, University of Cambridge, Cambridge, UK
| | - Jan Attig
- Department of Molecular Neuroscience, UCL Institute of Neurology, London, UK
| | - Jernej Ule
- Department of Molecular Neuroscience, UCL Institute of Neurology, London, UK
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115
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Aranda-Anzaldo A. The interphase mammalian chromosome as a structural system based on tensegrity. J Theor Biol 2016; 393:51-9. [PMID: 26780650 DOI: 10.1016/j.jtbi.2016.01.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2015] [Revised: 12/11/2015] [Accepted: 01/04/2016] [Indexed: 10/22/2022]
Abstract
Each mammalian chromosome is constituted by a DNA fiber of macroscopic length that needs to be fitted in a microscopic nucleus. The DNA fiber is subjected at physiological temperature to random thermal bending and looping that must be constrained so as achieve structural stability thus avoiding spontaneous rupturing of the fiber. Standard textbooks assume that chromatin proteins are primarily responsible for the packaging of DNA and so of its protection against spontaneous breakage. Yet the dynamic nature of the interactions between chromatin proteins and DNA is unlikely to provide the necessary long-term structural stability for the chromosomal DNA. On the other hand, longstanding evidence indicates that stable interactions between DNA and constituents of a nuclear compartment commonly known as the nuclear matrix organize the chromosomal DNA as a series of topologically constrained, supercoiled loops during interphase. This results in a primary level of DNA condensation and packaging within the nucleus, as well as in protection against spontaneous DNA breakage, independently of chromatin proteins which nevertheless increase and dynamically modulate the degree of DNA packaging and its role in the regulation of DNA function. Thus current evidence, presented hereunder, supports a model for the organization of the interphase chromosome as resilient system that satisfies the principles of structural tensegrity.
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Affiliation(s)
- Armando Aranda-Anzaldo
- Laboratorio de Biología Molecular y Neurociencias, Facultad de Medicina, Universidad Autónoma del Estado de México, Paseo Tollocan y Jesús Carranza s/n, Toluca, 50180 Edo. Méx., México.
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116
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Zhou Z, Yang Y, Konieczny SF, Irudayaraj JMK. Rapid and unbiased extraction of chromatin associated RNAs from purified native chromatin. J Chromatogr A 2015; 1426:64-8. [PMID: 26643718 DOI: 10.1016/j.chroma.2015.11.067] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Revised: 11/18/2015] [Accepted: 11/19/2015] [Indexed: 11/30/2022]
Abstract
An ultra fast and unbiased method that uses salicylic acid coated magnetic nanoparticles (SAMNPs) and magnetophoretic chromatography is developed to extract chromatin associated RNAs (CARs). The SAMNPs were first used for enriching cells from the cell culture media and further used for capturing chromatin after cells were lysed. The formed SAMNPs-chromatin complexes were transferred to a viscous polyethylene glycol (PEG) solution stored in a 200-μl pipette tip. Due to the difference in viscosities, a bi-layer liquid was formed inside the pipette tip. The SAMNPs-chromatin complexes were separated from the free SAMNPs and free RNA-SAMNPs complexes by applying an external magnetic field. The CARs were further extracted from the SAMNP-chromatin complexes directly. The extracted CARs were reverse transcribed as cDNA and further characterized by real-time qPCR. The total assay time taken for cell separation, chromatin purification and chromatin associated RNAs extraction can be accomplished in less than 2h.
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Affiliation(s)
- Zhongwu Zhou
- Bindley Bioscience Center, Purdue University, West Lafayette, IN 47907, USA; Department of Agricultural and Biological Engineering, Purdue University, West Lafayette, IN 47907, USA; Purdue Center for Cancer Research, Purdue University, West Lafayette, IN 47907, USA
| | - Yi Yang
- Bindley Bioscience Center, Purdue University, West Lafayette, IN 47907, USA; Purdue Center for Cancer Research, Purdue University, West Lafayette, IN 47907, USA; Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA
| | - Stephen F Konieczny
- Bindley Bioscience Center, Purdue University, West Lafayette, IN 47907, USA; Purdue Center for Cancer Research, Purdue University, West Lafayette, IN 47907, USA; Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA
| | - Joseph M K Irudayaraj
- Bindley Bioscience Center, Purdue University, West Lafayette, IN 47907, USA; Department of Agricultural and Biological Engineering, Purdue University, West Lafayette, IN 47907, USA; Purdue Center for Cancer Research, Purdue University, West Lafayette, IN 47907, USA.
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117
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Affiliation(s)
- Victoria H. Meller
- Department of Biological Sciences, Wayne State University, Detroit, Michigan 48202; , ,
| | - Sonal S. Joshi
- Department of Biological Sciences, Wayne State University, Detroit, Michigan 48202; , ,
| | - Nikita Deshpande
- Department of Biological Sciences, Wayne State University, Detroit, Michigan 48202; , ,
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118
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Aprea J, Calegari F. Long non-coding RNAs in corticogenesis: deciphering the non-coding code of the brain. EMBO J 2015; 34:2865-84. [PMID: 26516210 DOI: 10.15252/embj.201592655] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Accepted: 10/05/2015] [Indexed: 01/17/2023] Open
Abstract
Evidence on the role of long non-coding (lnc) RNAs has been accumulating over decades, but it has been only recently that advances in sequencing technologies have allowed the field to fully appreciate their abundance and diversity. Despite this, only a handful of lncRNAs have been phenotypically or mechanistically studied. Moreover, novel lncRNAs and new classes of RNAs are being discovered at growing pace, suggesting that this class of molecules may have functions as diverse as protein-coding genes. Interestingly, the brain is the organ where lncRNAs have the most peculiar features including the highest number of lncRNAs that are expressed, proportion of tissue-specific lncRNAs and highest signals of evolutionary conservation. In this work, we critically review the current knowledge about the steps that have led to the identification of the non-coding transcriptome including the general features of lncRNAs in different contexts in terms of both their genomic organisation, evolutionary origin, patterns of expression, and function in the developing and adult mammalian brain.
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Affiliation(s)
- Julieta Aprea
- DFG-Research Center and Cluster of Excellence for Regenerative Therapies, Faculty of Medicine, Technische Universität Dresden, Dresden, Germany
| | - Federico Calegari
- DFG-Research Center and Cluster of Excellence for Regenerative Therapies, Faculty of Medicine, Technische Universität Dresden, Dresden, Germany
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119
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Kelsey AD, Yang C, Leung D, Minks J, Dixon-McDougall T, Baldry SEL, Bogutz AB, Lefebvre L, Brown CJ. Impact of flanking chromosomal sequences on localization and silencing by the human non-coding RNA XIST. Genome Biol 2015; 16:208. [PMID: 26429547 PMCID: PMC4591629 DOI: 10.1186/s13059-015-0774-2] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2015] [Accepted: 09/10/2015] [Indexed: 01/07/2023] Open
Abstract
Background X-chromosome inactivation is a striking example of epigenetic silencing in which expression of the long non-coding RNA XIST initiates the heterochromatinization and silencing of one of the pair of X chromosomes in mammalian females. To understand how the RNA can establish silencing across millions of basepairs of DNA we have modelled the process by inducing expression of XIST from nine different locations in human HT1080 cells. Results Localization of XIST, depletion of Cot-1 RNA, perinuclear localization, and ubiquitination of H2A occurs at all sites examined, while recruitment of H3K9me3 was not observed. Recruitment of the heterochromatic features SMCHD1, macroH2A, H3K27me3, and H4K20me1 occurs independently of each other in an integration site-dependent manner. Silencing of flanking reporter genes occurs at all sites, but the spread of silencing to flanking endogenous human genes is variable in extent of silencing as well as extent of spread, with silencing able to skip regions. The spread of H3K27me3 and loss of H3K27ac correlates with the pre-existing levels of the modifications, and overall the extent of silencing correlates with the ability to recruit additional heterochromatic features. Conclusions The non-coding RNA XIST functions as a cis-acting silencer when expressed from nine different locations throughout the genome. A hierarchy among the features of heterochromatin reveals the importance of interaction with the local chromatin neighborhood for optimal spread of silencing, as well as the independent yet cooperative nature of the establishment of heterochromatin by the non-coding XIST RNA. Electronic supplementary material The online version of this article (doi:10.1186/s13059-015-0774-2) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Angela D Kelsey
- Department of Medical Genetics, Molecular Epigenetics Group, Life Sciences Institute, University of British Columbia, Vancouver, Canada.
| | - Christine Yang
- Department of Medical Genetics, Molecular Epigenetics Group, Life Sciences Institute, University of British Columbia, Vancouver, Canada.
| | - Danny Leung
- Ludwig Institute for Cancer Research, University of California at San Diego School of Medicine, La Jolla, CA, USA. .,Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China.
| | - Jakub Minks
- Department of Medical Genetics, Molecular Epigenetics Group, Life Sciences Institute, University of British Columbia, Vancouver, Canada.
| | - Thomas Dixon-McDougall
- Department of Medical Genetics, Molecular Epigenetics Group, Life Sciences Institute, University of British Columbia, Vancouver, Canada.
| | - Sarah E L Baldry
- Department of Medical Genetics, Molecular Epigenetics Group, Life Sciences Institute, University of British Columbia, Vancouver, Canada.
| | - Aaron B Bogutz
- Department of Medical Genetics, Molecular Epigenetics Group, Life Sciences Institute, University of British Columbia, Vancouver, Canada.
| | - Louis Lefebvre
- Department of Medical Genetics, Molecular Epigenetics Group, Life Sciences Institute, University of British Columbia, Vancouver, Canada.
| | - Carolyn J Brown
- Department of Medical Genetics, Molecular Epigenetics Group, Life Sciences Institute, University of British Columbia, Vancouver, Canada.
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120
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Trofimova I, Chervyakova D, Krasikova A. Transcription of subtelomere tandemly repetitive DNA in chicken embryogenesis. Chromosome Res 2015; 23:495-503. [DOI: 10.1007/s10577-015-9487-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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121
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Cerase A, Pintacuda G, Tattermusch A, Avner P. Xist localization and function: new insights from multiple levels. Genome Biol 2015; 16:166. [PMID: 26282267 PMCID: PMC4539689 DOI: 10.1186/s13059-015-0733-y] [Citation(s) in RCA: 122] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2015] [Accepted: 07/29/2015] [Indexed: 12/21/2022] Open
Abstract
In female mammals, one of the two X chromosomes in each cell is transcriptionally silenced in order to achieve dosage compensation between the genders in a process called X chromosome inactivation. The master regulator of this process is the long non-coding RNA Xist. During X-inactivation, Xist accumulates in cis on the future inactive X chromosome, triggering a cascade of events that provoke the stable silencing of the entire chromosome, with relatively few genes remaining active. How Xist spreads, what are its binding sites, how it recruits silencing factors and how it induces a specific topological and nuclear organization of the chromatin all remain largely unanswered questions. Recent studies have improved our understanding of Xist localization and the proteins with which it interacts, allowing a reappraisal of ideas about Xist function. We discuss recent advances in our knowledge of Xist-mediated silencing, focusing on Xist spreading, the nuclear organization of the inactive X chromosome, recruitment of the polycomb complex and the role of the nuclear matrix in the process of X chromosome inactivation.
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Affiliation(s)
- Andrea Cerase
- EMBL Mouse Biology Unit, Monterotondo, 00015 (RM), Italy.
| | - Greta Pintacuda
- Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK
| | - Anna Tattermusch
- Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK
| | - Philip Avner
- EMBL Mouse Biology Unit, Monterotondo, 00015 (RM), Italy. .,Institut Pasteur, Unite de Genetique Moleculaire Murine, CNRS, URA2578, Paris, France.
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122
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Lisitsyn NA, Chernyi AA, Karpov VL, Beresten SF. A role of long noncoding RNAs in carcinogenesis. Mol Biol 2015. [DOI: 10.1134/s002689331504010x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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123
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Affiliation(s)
- Dorota Skowronska-Krawczyk
- a Howard Hughes Medical Institute; Department of Medicine; School of Medicine ; University of California San Diego ; La Jolla , CA USA
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124
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Vilborg A, Passarelli MC, Yario TA, Tycowski KT, Steitz JA. Widespread Inducible Transcription Downstream of Human Genes. Mol Cell 2015; 59:449-61. [PMID: 26190259 DOI: 10.1016/j.molcel.2015.06.016] [Citation(s) in RCA: 122] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Revised: 04/29/2015] [Accepted: 06/10/2015] [Indexed: 01/09/2023]
Abstract
Pervasive transcription of the human genome generates RNAs whose mode of formation and functions are largely uncharacterized. Here, we combine RNA-seq with detailed mechanistic studies to describe a transcript type derived from protein-coding genes. The resulting RNAs, which we call DoGs for downstream of gene containing transcripts, possess long non-coding regions (often >45 kb) and remain chromatin bound. DoGs are inducible by osmotic stress through an IP3 receptor signaling-dependent pathway, indicating active regulation. DoG levels are increased by decreased termination of the upstream transcript, a previously undescribed mechanism for rapid transcript induction. Relative depletion of polyA signals in DoG regions correlates with increased levels of DoGs after osmotic stress. We detect DoG transcription in several human cell lines and provide evidence for thousands of DoGs genome wide.
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Affiliation(s)
- Anna Vilborg
- Department of Molecular Biophysics and Biochemistry, Howard Hughes Medical Institute, Boyer Center for Molecular Medicine, Yale University School of Medicine, 295 Congress Avenue, New Haven, CT 06536, USA
| | - Maria C Passarelli
- Department of Molecular Biophysics and Biochemistry, Howard Hughes Medical Institute, Boyer Center for Molecular Medicine, Yale University School of Medicine, 295 Congress Avenue, New Haven, CT 06536, USA
| | - Therese A Yario
- Department of Molecular Biophysics and Biochemistry, Howard Hughes Medical Institute, Boyer Center for Molecular Medicine, Yale University School of Medicine, 295 Congress Avenue, New Haven, CT 06536, USA
| | - Kazimierz T Tycowski
- Department of Molecular Biophysics and Biochemistry, Howard Hughes Medical Institute, Boyer Center for Molecular Medicine, Yale University School of Medicine, 295 Congress Avenue, New Haven, CT 06536, USA
| | - Joan A Steitz
- Department of Molecular Biophysics and Biochemistry, Howard Hughes Medical Institute, Boyer Center for Molecular Medicine, Yale University School of Medicine, 295 Congress Avenue, New Haven, CT 06536, USA.
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125
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Johnson GD, Mackie P, Jodar M, Moskovtsev S, Krawetz SA. Chromatin and extracellular vesicle associated sperm RNAs. Nucleic Acids Res 2015; 43:6847-59. [PMID: 26071953 PMCID: PMC4538811 DOI: 10.1093/nar/gkv591] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Accepted: 05/23/2015] [Indexed: 12/16/2022] Open
Abstract
A diverse pool of RNAs remain encapsulated within the transcriptionally silent spermatozoon despite the dramatic reduction in cellular and nuclear volume following cytoplasm/nucleoplasm expulsion. The impact of this pronounced restructuring on the distribution of transcripts inside the sperm essentially remains unknown. To define their compartmentalization, total RNA >100 nt was extracted from sonicated (SS) mouse spermatozoa and detergent demembranated sucrose gradient fractionated (Cs/Tx) sperm heads. Sperm RNAs predominately localized toward the periphery. The corresponding distribution of transcripts and thus localization and complexity were then inferred by RNA-seq. Interestingly, the number of annotated RNAs in the CsTx sperm heads exhibiting reduced peripheral enrichment was restricted. However this included Cabyr, the calcium-binding tyrosine phosphorylation-regulated protein encoded transcript. It is present in murine zygotes prior to the maternal to the zygotic transition yet absent in oocytes, consistent with the delivery of internally positioned sperm-borne RNAs to the embryo. In comparison, transcripts enriched in sonicated sperm contributed to the mitochondria and exosomes along with several nuclear transcripts including the metastasis associated lung adenocarcinoma transcript 1 (Malat1) and several small nucleolar RNAs. Their preferential peripheral localization suggests that chromatin remodeling during spermiogenesis is not limited to nucleoproteins as part of the nucleoprotein exchange.
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Affiliation(s)
- Graham D Johnson
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI 48201, USA
| | - Paula Mackie
- CReATe Fertility Centre, Toronto, ON, M5G 1N8, Canada
| | - Meritxell Jodar
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI 48201, USA Department of Obstetrics and Gynaecology, University of Toronto, ON, M5G 1E2, Canada
| | - Sergey Moskovtsev
- CReATe Fertility Centre, Toronto, ON, M5G 1N8, Canada Department of Obstetrics and Gynecology, Wayne State University School of Medicine, Detroit, MI 48201, USA
| | - Stephen A Krawetz
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI 48201, USA Department of Obstetrics and Gynaecology, University of Toronto, ON, M5G 1E2, Canada
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126
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Cremer T, Cremer M, Hübner B, Strickfaden H, Smeets D, Popken J, Sterr M, Markaki Y, Rippe K, Cremer C. The 4D nucleome: Evidence for a dynamic nuclear landscape based on co-aligned active and inactive nuclear compartments. FEBS Lett 2015; 589:2931-43. [PMID: 26028501 DOI: 10.1016/j.febslet.2015.05.037] [Citation(s) in RCA: 162] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2015] [Revised: 05/19/2015] [Accepted: 05/20/2015] [Indexed: 02/04/2023]
Abstract
Recent methodological advancements in microscopy and DNA sequencing-based methods provide unprecedented new insights into the spatio-temporal relationships between chromatin and nuclear machineries. We discuss a model of the underlying functional nuclear organization derived mostly from electron and super-resolved fluorescence microscopy studies. It is based on two spatially co-aligned, active and inactive nuclear compartments (ANC and INC). The INC comprises the compact, transcriptionally inactive core of chromatin domain clusters (CDCs). The ANC is formed by the transcriptionally active periphery of CDCs, called the perichromatin region (PR), and the interchromatin compartment (IC). The IC is connected to nuclear pores and serves nuclear import and export functions. The ANC is the major site of RNA synthesis. It is highly enriched in epigenetic marks for transcriptionally competent chromatin and RNA Polymerase II. Marks for silent chromatin are enriched in the INC. Multi-scale cross-correlation spectroscopy suggests that nuclear architecture resembles a random obstacle network for diffusing proteins. An increased dwell time of proteins and protein complexes within the ANC may help to limit genome scanning by factors or factor complexes to DNA exposed within the ANC.
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Affiliation(s)
- Thomas Cremer
- Biocenter, Department Biology II, Ludwig Maximilians University (LMU), Martinsried, Germany.
| | - Marion Cremer
- Biocenter, Department Biology II, Ludwig Maximilians University (LMU), Martinsried, Germany
| | - Barbara Hübner
- Biocenter, Department Biology II, Ludwig Maximilians University (LMU), Martinsried, Germany
| | - Hilmar Strickfaden
- University of Alberta, Cross Cancer Institute Dept. of Oncology, Edmonton, AB, Canada
| | - Daniel Smeets
- Biocenter, Department Biology II, Ludwig Maximilians University (LMU), Martinsried, Germany
| | - Jens Popken
- Biocenter, Department Biology II, Ludwig Maximilians University (LMU), Martinsried, Germany
| | - Michael Sterr
- Biocenter, Department Biology II, Ludwig Maximilians University (LMU), Martinsried, Germany
| | - Yolanda Markaki
- Biocenter, Department Biology II, Ludwig Maximilians University (LMU), Martinsried, Germany
| | - Karsten Rippe
- German Cancer Research Center (DKFZ) & BioQuant Center, Research Group Genome Organization & Function, Heidelberg, Germany.
| | - Christoph Cremer
- Institute of Molecular Biology (IMB), Mainz and Institute of Pharmacy and Molecular Biotechnology (IPMB), University of Heidelberg, Germany.
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127
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Jachowicz JW, Torres-Padilla ME. LINEs in mice: features, families, and potential roles in early development. Chromosoma 2015; 125:29-39. [PMID: 25975894 DOI: 10.1007/s00412-015-0520-2] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Revised: 04/27/2015] [Accepted: 05/05/2015] [Indexed: 01/08/2023]
Abstract
Approximately half of the mammalian genome is composed of repetitive elements, including LINE-1 (L1) elements. Because of their potential ability to transpose and integrate into other regions of the genome, their activation represents a threat to genome stability. Molecular pathways have emerged to tightly regulate and repress their transcriptional activity, including DNA methylation, histone modifications, and RNA pathways. It has become evident that Line-L1 elements are evolutionary diverse and dedicated repression pathways have been recently uncovered that discriminate between evolutionary old and young elements, with RNA-directed silencing mechanisms playing a prominent role. During periods of epigenetic reprogramming in development, specific classes of repetitive elements are upregulated, presumably due to the loss of most heterochromatic marks in this process. While we have learnt a lot on the molecular mechanisms that regulate Line-L1 expression over the last years, it is still unclear whether reactivation of Line-L1 after fertilization serves a functional purpose or it is a simple side effect of reprogramming.
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Affiliation(s)
- Joanna W Jachowicz
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS/INSERM U964, Université de Strasbourg, 67404, Illkirch, France
| | - Maria-Elena Torres-Padilla
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS/INSERM U964, Université de Strasbourg, 67404, Illkirch, France.
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128
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A cluster of noncoding RNAs activates the ESR1 locus during breast cancer adaptation. Nat Commun 2015; 6:6966. [PMID: 25923108 PMCID: PMC4421845 DOI: 10.1038/ncomms7966] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2015] [Accepted: 03/20/2015] [Indexed: 02/07/2023] Open
Abstract
Estrogen receptor-α (ER)-positive breast cancer cells undergo hormone-independent proliferation after deprivation of oestrogen, leading to endocrine therapy resistance. Up-regulation of the ER gene (ESR1) is critical for this process, but the underlying mechanisms remain unclear. Here we show that the combination of transcriptome and fluorescence in situ hybridization analyses revealed that oestrogen deprivation induced a cluster of noncoding RNAs that defined a large chromatin domain containing the ESR1 locus. We termed these RNAs as Eleanors (ESR1 locus enhancing and activating noncoding RNAs). Eleanors were present in ER-positive breast cancer tissues and localized at the transcriptionally active ESR1 locus to form RNA foci. Depletion of one Eleanor, upstream (u)-Eleanor, impaired cell growth and transcription of intragenic Eleanors and ESR1 mRNA, indicating that Eleanors cis-activate the ESR1 gene. Eleanor-mediated gene activation represents a new type of locus control mechanism and plays an essential role in the adaptation of breast cancer cells. Estrogen-receptor-positive breast cancer cells undergo hormone-independent proliferation after long-term oestrogen deprivation and become resistant to endocrine therapies. Here, the authors report a cluster of noncoding RNAs important for this adaptation process.
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129
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Caudron-Herger M, Cook PR, Rippe K, Papantonis A. Dissecting the nascent human transcriptome by analysing the RNA content of transcription factories. Nucleic Acids Res 2015; 43:e95. [PMID: 25897132 PMCID: PMC4538806 DOI: 10.1093/nar/gkv390] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2015] [Accepted: 04/13/2015] [Indexed: 11/21/2022] Open
Abstract
While mapping total and poly-adenylated human transcriptomes has now become routine, characterizing nascent transcripts remains challenging, largely because nascent RNAs have such short half-lives. Here, we describe a simple, fast and cost-effective method to isolate RNA associated with transcription factories, the sites responsible for the majority of nuclear transcription. Following stimulation of human endothelial cells with the pro-inflammatory cytokine TNFα, we isolate and analyse the RNA content of factories by sequencing. Comparison with total, poly(A)+ and chromatin RNA fractions reveals that sequencing of purified factory RNA maps the complete nascent transcriptome; it is rich in intronic unprocessed transcript, as well as long intergenic non-coding (lincRNAs) and enhancer-associated RNAs (eRNAs), micro-RNA precursors and repeat-derived RNAs. Hence, we verify that transcription factories produce most nascent RNA and confer a regulatory role via their association with a set of specifically-retained non-coding transcripts.
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Affiliation(s)
| | - Peter R Cook
- Sir William Dunn School of Pathology, University of Oxford, OX1 3RE Oxford, UK
| | - Karsten Rippe
- Deutsches Krebsforschungszentrum (DKFZ) & BioQuant, D-69120 Heidelberg, Germany
| | - Argyris Papantonis
- Sir William Dunn School of Pathology, University of Oxford, OX1 3RE Oxford, UK Center for Molecular Medicine, University of Cologne, D-50931 Cologne, Germany
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130
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St Laurent G, Wahlestedt C, Kapranov P. The Landscape of long noncoding RNA classification. Trends Genet 2015; 31:239-51. [PMID: 25869999 DOI: 10.1016/j.tig.2015.03.007] [Citation(s) in RCA: 830] [Impact Index Per Article: 92.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2015] [Revised: 03/09/2015] [Accepted: 03/12/2015] [Indexed: 12/12/2022]
Abstract
Advances in the depth and quality of transcriptome sequencing have revealed many new classes of long noncoding RNAs (lncRNAs). lncRNA classification has mushroomed to accommodate these new findings, even though the real dimensions and complexity of the noncoding transcriptome remain unknown. Although evidence of functionality of specific lncRNAs continues to accumulate, conflicting, confusing, and overlapping terminology has fostered ambiguity and lack of clarity in the field in general. The lack of fundamental conceptual unambiguous classification framework results in a number of challenges in the annotation and interpretation of noncoding transcriptome data. It also might undermine integration of the new genomic methods and datasets in an effort to unravel the function of lncRNA. Here, we review existing lncRNA classifications, nomenclature, and terminology. Then, we describe the conceptual guidelines that have emerged for their classification and functional annotation based on expanding and more comprehensive use of large systems biology-based datasets.
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Affiliation(s)
- Georges St Laurent
- St. Laurent Institute, 317 New Boston St., Suite 201, Woburn, MA 01801 USA; Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, 185 Meeting Street, Providence, RI 02912, USA
| | - Claes Wahlestedt
- Center for Therapeutic Innovation and Department of Psychiatry and Behavioral Sciences, University of Miami Miller School of Medicine, 1501 NW 10th Ave, Miami, FL 33136 USA.
| | - Philipp Kapranov
- Institute of Genomics, School of Biomedical Sciences, Huaqiao Univerisity, 668 Jimei Road, Xiamen, China 361021; St. Laurent Institute, 317 New Boston St., Suite 201, Woburn, MA 01801 USA.
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131
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Montiel EE, Ruiz-Ruano FJ, Cabrero J, Marchal JA, Sánchez A, Perfectti F, López-León MD, Camacho JPM. Intragenomic distribution of RTE retroelements suggests intrachromosomal movement. Chromosome Res 2015; 23:211-23. [PMID: 25605325 DOI: 10.1007/s10577-014-9461-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2014] [Revised: 11/25/2014] [Accepted: 12/18/2014] [Indexed: 11/25/2022]
Abstract
Much is known about the abundance of transposable elements (TEs) in eukaryotic genomes, but much is still unknown on their behaviour within cells. We employ here a combination of cytological, molecular and genomic approaches providing information on the intragenomic distribution and behaviour of non-long terminal repeat (LTR) retrotransposon-like elements (RTE). We microdissected every chromosome in a single first meiotic metaphase cell of the grasshopper Eyprepocnemis plorans and polymerase chain reaction (PCR) amplified a fragment of the RTE reverse transcriptase gene with specific primers. PCR products were cloned and 139 clones were sequenced. Analysis of molecular variance (AMOVA) showed significant intragenomic structure for these elements, with 4.6 % of molecular variance being found between chromosomes. A maximum likelihood tree built with the RTE sequences revealed the frequent presence of two or more elements showing very high similarity and being located on the same chromosome, thus suggesting intrachromosome movement. The 454 pyrosequencing of genomic DNA gave strong support to the microdissection results and provided evidence for the existence of 5' truncated elements. Our results thus indicate a tendency of RTE elements to reinsert into the same chromosome from where they were transcribed, which could be achieved if retrotranscription and insertion takes place immediately after transcription.
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Affiliation(s)
- Eugenia E Montiel
- Departamento de Genética, Facultad de Ciencias, Universidad de Granada, Granada, 18071, Spain,
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Donley N, Smith L, Thayer MJ. ASAR15, A cis-acting locus that controls chromosome-wide replication timing and stability of human chromosome 15. PLoS Genet 2015; 11:e1004923. [PMID: 25569254 PMCID: PMC4287527 DOI: 10.1371/journal.pgen.1004923] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2014] [Accepted: 11/25/2014] [Indexed: 01/01/2023] Open
Abstract
DNA replication initiates at multiple sites along each mammalian chromosome at different times during each S phase, following a temporal replication program. We have used a Cre/loxP-based strategy to identify cis-acting elements that control this replication-timing program on individual human chromosomes. In this report, we show that rearrangements at a complex locus at chromosome 15q24.3 result in delayed replication and structural instability of human chromosome 15. Characterization of this locus identified long, RNA transcripts that are retained in the nucleus and form a “cloud” on one homolog of chromosome 15. We also found that this locus displays asynchronous replication that is coordinated with other random monoallelic genes on chromosome 15. We have named this locus ASynchronous replication and Autosomal RNA on chromosome 15, or ASAR15. Previously, we found that disruption of the ASAR6 lincRNA gene results in delayed replication, delayed mitotic condensation and structural instability of human chromosome 6. Previous studies in the mouse found that deletion of the Xist gene, from the X chromosome in adult somatic cells, results in a delayed replication and instability phenotype that is indistinguishable from the phenotype caused by disruption of either ASAR6 or ASAR15. In addition, delayed replication and chromosome instability were detected following structural rearrangement of many different human or mouse chromosomes. These observations suggest that all mammalian chromosomes contain similar cis-acting loci. Thus, under this scenario, all mammalian chromosomes contain four distinct types of essential cis-acting elements: origins, telomeres, centromeres and “inactivation/stability centers”, all functioning to promote proper replication, segregation and structural stability of each chromosome. Mammalian cells replicate their DNA along each chromosome during a precise temporal replication program. In this report, we used a novel “chromosome-engineering” strategy to identify a DNA element that controls this replication-timing program of human chromosome 15. Characterization of this element indicated that it encodes large non-protein-coding RNAs that are retained in the nucleus and form a “cloud” on one copy of chromosome 15. Previously, we found that structural rearrangements of a similar element on human chromosome 6 causes delayed replication and structural instability of chromosome 6. Mammalian chromosomes are known to contain three distinct types of essential DNA elements that promote proper chromosome function. Thus, every chromosome contains: 1) origins of replication, which are responsible for proper initiation of DNA synthesis; 2) centromeres, which are responsible for proper chromosome separation during cell division; and 3) telomeres, which are responsible for replication and protection of the ends of linear chromosomes. Our work supports a model in which all mammalian chromosomes contain a fourth type of essential DNA element, the “inactivation/stability center”, which is responsible for proper DNA replication timing and structural stability of each chromosome.
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Affiliation(s)
- Nathan Donley
- Department of Biochemistry and Molecular Biology, Oregon Health & Science University, Portland, Oregon, United States of America
| | - Leslie Smith
- Department of Biochemistry and Molecular Biology, Oregon Health & Science University, Portland, Oregon, United States of America
| | - Mathew J. Thayer
- Department of Biochemistry and Molecular Biology, Oregon Health & Science University, Portland, Oregon, United States of America
- * E-mail:
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Trofimova I, Popova D, Vasilevskaya E, Krasikova A. Non-coding RNA derived from a conservative subtelomeric tandem repeat in chicken and Japanese quail somatic cells. Mol Cytogenet 2014; 7:102. [PMID: 25610495 PMCID: PMC4301066 DOI: 10.1186/s13039-014-0102-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2014] [Accepted: 12/12/2014] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Subtelomeres are located close to the ends of chromosomes and organized by tandemly repetitive sequences, duplicated copies of genes, pseudogenes and retrotransposons. Transcriptional activity of tandemly organized DNA at terminal chromosomal regions and the distribution of subtelomere-derived non-coding RNAs are poorly investigated. Here we aimed to analyze transcriptional activity of subtelomeric tandem repeat in somatic tissues and cultured cells of birds. We focused on tissue-specific differences of subtelomeric repeats transcription, structure of the resulting transcripts and the behavior of subtelomere-derived RNA during mitosis. RESULTS Transcriptional activity of short subtelomeric PO41 ("pattern of 41 bp") tandem repeat in the somatic and cultured cells of chicken (Gallus gallus domesticus) and Japanese quail (Coturnix coturnix japonica) was examined using RNA fluorescence in situ hybridization approach. We discovered transcripts from both strands of the PO41 repeat in chicken MDCC-MSB1 cells as well as in chicken and Japanese quail somatic tissues, such as tissues of cerebellum, telencephalon, muscles, oviduct, small and large intestine. Normal somatic and transformed cells demonstrate similar distribution of PO41 repeat transcripts in interphase nuclei. We revealed one or two major foci of PO41 repeat transcripts associated with RNA polymerase II, representing nascent RNA, and dispersed PO41 repeat transcripts localized in euchromatin or interchromatin space, representing released RNA. During mitosis PO41 non-coding RNA distribute between condensed chromosomes till anaphase, when they concentrate at the cleavage plane. At telophase, clusters of PO41 RNA surround terminal regions of chromosomes. Treatments with RNases of different substrate specificity indicate that PO41 repeat transcripts are single-stranded RNAs with short double-stranded regions due to appearance of inverted repeats. CONCLUSION Transcription of a subtelomeric tandem repeat in avian somatic cells is reported here for the first time. PO41 repeat transcription is conserved among Galliformes and has similar pattern in somatic tissues. We demonstrated redistribution of non-coding PO41 RNA occurring during the cell cycle. Potential regulatory role of the PO41 repeat transcripts in RNA-dependent process of subtelomere heterochromatin maintenance is discussed.
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Affiliation(s)
- Irina Trofimova
- Department of Cytology and Histology, Saint-Petersburg State University, Oranienbaumskoie sch. 2, Stary Peterhof, 198504 Saint-Petersburg, Russia
| | - Darya Popova
- Department of Cytology and Histology, Saint-Petersburg State University, Oranienbaumskoie sch. 2, Stary Peterhof, 198504 Saint-Petersburg, Russia
| | - Elena Vasilevskaya
- Department of Cytology and Histology, Saint-Petersburg State University, Oranienbaumskoie sch. 2, Stary Peterhof, 198504 Saint-Petersburg, Russia
| | - Alla Krasikova
- Department of Cytology and Histology, Saint-Petersburg State University, Oranienbaumskoie sch. 2, Stary Peterhof, 198504 Saint-Petersburg, Russia
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134
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Affiliation(s)
- Sandra R. Richardson
- Mater Research Institute, The University of Queensland, Translational Research Institute, Woolloongabba QLD 4102, Australia;
| | - Santiago Morell
- Mater Research Institute, The University of Queensland, Translational Research Institute, Woolloongabba QLD 4102, Australia;
| | - Geoffrey J. Faulkner
- Mater Research Institute, The University of Queensland, Translational Research Institute, Woolloongabba QLD 4102, Australia;
- School of Biomedical Sciences, The University of Queensland, Brisbane QLD 4072, Australia
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135
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Cebrià-Costa JP, Millanes-Romero A, de Herreros AG, Peiró S. The Epithelial-to-Mesenchymal Transition (EMT), a Particular Case. Mol Cell Oncol 2014; 1:e960770. [PMID: 27308335 PMCID: PMC4905179 DOI: 10.4161/23723548.2014.960770] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2014] [Revised: 07/25/2014] [Accepted: 08/01/2014] [Indexed: 01/05/2023]
Abstract
Constitutive heterochromatin, an essential structure that has been conserved throughout evolution, is required to maintain genome stability. Although heterochromatin is enriched for repressive traits, it can be actively transcribed to generate thousands of noncoding RNAs that are required for correct chromatin assembly. Despite the importance of this structure, how and why heterochromatin transcription is regulated, and the proteins responsible for this regulation, remain poorly understood. Here, we summarize recent findings in heterochromatin transcription regulation during different cellular processes with a focus on the epithelial–mesenchymal transition (EMT), which elicits important changes in cell behavior, has a key role in early development, and is involved in cancer progression.
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Affiliation(s)
- Joan Pau Cebrià-Costa
- Programa de Recerca en Càncer; IMIM (Institut Hospital del Mar d'Investigacions Mèdiques) ; Barcelona, Spain
| | | | - Antonio García de Herreros
- Programa de Recerca en Càncer; IMIM (Institut Hospital del Mar d'Investigacions Mèdiques); Barcelona, Spain; Departament de Ciències Experimentals i de la Salut; Universitat Pompeu Fabra; Barcelona, Spain
| | - Sandra Peiró
- Programa de Recerca en Càncer; IMIM (Institut Hospital del Mar d'Investigacions Mèdiques) ; Barcelona, Spain
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136
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Repetitive elements dynamics in cell identity programming, maintenance and disease. Curr Opin Cell Biol 2014; 31:67-73. [PMID: 25240822 DOI: 10.1016/j.ceb.2014.09.002] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2014] [Revised: 09/02/2014] [Accepted: 09/03/2014] [Indexed: 01/08/2023]
Abstract
The days of 'junk DNA' seem to be over. The rapid progress of genomics technologies has been unveiling unexpected mechanisms by which repetitive DNA and in particular transposable elements (TEs) have evolved, becoming key issues in understanding genome structure and function. Indeed, rather than 'parasites', recent findings strongly suggest that TEs may have a positive function by contributing to tissue specific transcriptional programs, in particular as enhancer-like elements and/or modules for regulation of higher order chromatin structure. Further, it appears that during development and aging genomes experience several waves of TEs activation, and this contributes to individual genome shaping during lifetime. Interestingly, TEs activity is major target of epigenomic regulation. These findings are shedding new light on the genome-phenotype relationship and set the premises to help to explain complex disease manifestation, as consequence of TEs activity deregulation.
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137
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Engelke R, Riede J, Hegermann J, Wuerch A, Eimer S, Dengjel J, Mittler G. The Quantitative Nuclear Matrix Proteome as a Biochemical Snapshot of Nuclear Organization. J Proteome Res 2014; 13:3940-56. [DOI: 10.1021/pr500218f] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Rudolf Engelke
- Max Planck Institute of Immunobiology and Epigenetics, Stübeweg 51, 79108 Freiburg, Germany
| | - Julia Riede
- Freiburg
Institute for Advanced Studies, School of Life Sciences − LifeNet, University of Freiburg, Albertstrasse 19, 79104 Freiburg, Germany
- Center
for Biological Systems Analysis, University of Freiburg, Habsburgerstrasse
49, 79104 Freiburg, Germany
| | - Jan Hegermann
- European Neuroscience Institute and Center for Molecular Physiology of the Brain (CMPB), 37077 Göttingen, Germany
| | - Andreas Wuerch
- Max Planck Institute of Immunobiology and Epigenetics, Stübeweg 51, 79108 Freiburg, Germany
| | - Stefan Eimer
- European Neuroscience Institute and Center for Molecular Physiology of the Brain (CMPB), 37077 Göttingen, Germany
| | - Joern Dengjel
- Freiburg
Institute for Advanced Studies, School of Life Sciences − LifeNet, University of Freiburg, Albertstrasse 19, 79104 Freiburg, Germany
- Center
for Biological Systems Analysis, University of Freiburg, Habsburgerstrasse
49, 79104 Freiburg, Germany
| | - Gerhard Mittler
- Max Planck Institute of Immunobiology and Epigenetics, Stübeweg 51, 79108 Freiburg, Germany
- BIOSS,
Center for Biological Signalling Studies, University of Freiburg, Schänzlestrasse 18, 79104 Freiburg, Germany
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138
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Retrotransposons in pluripotent cells: Impact and new roles in cellular plasticity. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2014; 1849:417-26. [PMID: 25042909 DOI: 10.1016/j.bbagrm.2014.07.007] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2014] [Revised: 07/08/2014] [Accepted: 07/10/2014] [Indexed: 12/27/2022]
Abstract
Transposable Elements are pieces of DNA able to mobilize from one location to another within genomes. Although they constitute more than 50% of the human genome, they have been classified as selfish DNA, with the only mission to spread within genomes and generate more copies of themselves that will ensure their presence over generations. Despite their remarkable prevalence, only a minor group of transposable elements remain active in the human genome and can sporadically be associated with the generation of a genetic disorder due to their ongoing mobility. Most of the transposable elements identified in the human genome corresponded to fixed insertions that no longer move in genomes. As selfish DNA, transposable element insertions accumulate in cell types where genetic information can be passed to the next generation. Indeed, work from different laboratories has demonstrated that the main heritable load of TE accumulation in humans occurs during early embryogenesis. Thus, active transposable elements have a clear impact on our pluripotent genome. However, recent findings suggest that the main proportion of fixed non-mobile transposable elements might also have emerging roles in cellular plasticity. In this concise review, we provide an overview of the impact of currently active transposable elements in our pluripotent genome and further discuss new roles of transposable elements (active or not) in regulating pluripotency. This article is part of a Special Issue entitled: Stress as a fundamental theme in cell plasticity.
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139
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Peeters SB, Cotton AM, Brown CJ. Variable escape from X-chromosome inactivation: identifying factors that tip the scales towards expression. Bioessays 2014; 36:746-56. [PMID: 24913292 PMCID: PMC4143967 DOI: 10.1002/bies.201400032] [Citation(s) in RCA: 74] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
In humans over 15% of X-linked genes have been shown to ‘escape’ from X-chromosome inactivation (XCI): they continue to be expressed to some extent from the inactive X chromosome. Mono-allelic expression is anticipated within a cell for genes subject to XCI, but random XCI usually results in expression of both alleles in a cell population. Using a study of allelic expression from cultured lymphoblasts and fibroblasts, many of which showed substantial skewing of XCI, we recently reported that the expression of genes lies on a contiunuum between those that are subject to inactivation, and those that escape. We now review allelic expression studies from mouse, and discuss the variability in escape seen in both humans and mice in genic expression levels, between X chromosomes and between tissues. We also discuss current knowledge of the heterochromatic features, DNA elements and three-dimensional topology of the inactive X that contribute to the balance of expression from the otherwise inactive X chromosome.
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Affiliation(s)
- Samantha B Peeters
- Department of Medical Genetics, Molecular Epigenetics Group, Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada
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140
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Abstract
RNA has been proposed to be a component of an underlying nuclear matrix. Hall et al. show that noncoding, repetitive RNAs, some derived from LINE1 elements, stably associate with interphase chromosomes and copurify with nuclear scaffold, indicating that RNAs might impact interphase chromosome architecture.
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Affiliation(s)
- Ryu-Suke Nozawa
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, The University of Edinburgh, Crewe Road, Edinburgh EH4 2XU, UK
| | - Nick Gilbert
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, The University of Edinburgh, Crewe Road, Edinburgh EH4 2XU, UK.
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141
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Abstract
A striking finding in the past decade is the production of numerous non-coding RNAs (ncRNAs) from mammalian genomes. While it is entirely possible that many of those ncRNAs are transcription noises or by-products of RNA processing, increasing evidence suggests that a large fraction of them are functional and provide various regulatory activities in the cell. Thus, functional genomics and proteomics are incomplete without understanding functional ribonomics. As has been long suggested by the 'RNA world' hypothesis, many ncRNAs have the capacity to act like proteins in diverse biochemical processes. The enormous amount of information residing in the primary sequences and secondary structures of ncRNAs makes them particularly suited to function as scaffolds for molecular interactions. In addition, their functions appear to be stringently controlled by default via abundant nucleases when not engaged in specific interactions. This review focuses on the functional properties of regulatory ncRNAs in comparison with proteins and emphasizes both the opportunities and challenges in future ncRNA research.
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Affiliation(s)
- Xiang-Dong Fu
- Department of Cellular and Molecular Medicine, Institute of Genomic Medicine, University of California, San Diego, La Jolla, CA 92093-0651, USA
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142
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Burgess DJ. Chromosome roles for repetitive RNAs. Nat Rev Genet 2014. [DOI: 10.1038/nrg3709] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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