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Thayer M, Heskett MB, Smith LG, Spellman PT, Yates PA. ASAR lncRNAs control DNA replication timing through interactions with multiple hnRNP/RNA binding proteins. eLife 2024; 13:RP95898. [PMID: 38896448 PMCID: PMC11186638 DOI: 10.7554/elife.95898] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/21/2024] Open
Abstract
ASARs are a family of very-long noncoding RNAs that control replication timing on individual human autosomes, and are essential for chromosome stability. The eight known ASAR lncRNAs remain closely associated with their parent chromosomes. Analysis of RNA-protein interaction data (from ENCODE) revealed numerous RBPs with significant interactions with multiple ASAR lncRNAs, with several hnRNPs as abundant interactors. An ~7 kb domain within the ASAR6-141 lncRNA shows a striking density of RBP interaction sites. Genetic deletion and ectopic integration assays indicate that this ~7 kb RNA binding protein domain contains functional sequences for controlling replication timing of entire chromosomes in cis. shRNA-mediated depletion of 10 different RNA binding proteins, including HNRNPA1, HNRNPC, HNRNPL, HNRNPM, HNRNPU, or HNRNPUL1, results in dissociation of ASAR lncRNAs from their chromosome territories, and disrupts the synchronous replication that occurs on all autosome pairs, recapitulating the effect of individual ASAR knockouts on a genome-wide scale. Our results further demonstrate the role that ASARs play during the temporal order of genome-wide replication, and we propose that ASARs function as essential RNA scaffolds for the assembly of hnRNP complexes that help maintain the structural integrity of each mammalian chromosome.
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Affiliation(s)
- Mathew Thayer
- Department of Chemical Physiology and Biochemistry,Oregon Health & Science UniversityPortlandUnited States
| | - Michael B Heskett
- Department of Molecular and Medical Genetics, Oregon Health & Science UniversityPortlandUnited States
- Stanford Cancer InstituteStanfordUnited States
| | - Leslie G Smith
- Department of Chemical Physiology and Biochemistry,Oregon Health & Science UniversityPortlandUnited States
| | - Paul T Spellman
- Department of Molecular and Medical Genetics, Oregon Health & Science UniversityPortlandUnited States
- Cancer Early Detection Advanced Research Center, Knight Cancer Institute, Oregon Health & Science UniversityPortlandUnited States
| | - Phillip A Yates
- Department of Chemical Physiology and Biochemistry,Oregon Health & Science UniversityPortlandUnited States
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2
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Heskett MB, Vouzas AE, Smith LG, Yates PA, Boniface C, Bouhassira EE, Spellman PT, Gilbert DM, Thayer MJ. Epigenetic control of chromosome-associated lncRNA genes essential for replication and stability. Nat Commun 2022; 13:6301. [PMID: 36273230 PMCID: PMC9588035 DOI: 10.1038/s41467-022-34099-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Accepted: 10/13/2022] [Indexed: 01/18/2023] Open
Abstract
ASARs are long noncoding RNA genes that control replication timing of entire human chromosomes in cis. The three known ASAR genes are located on human chromosomes 6 and 15, and are essential for chromosome integrity. To identify ASARs on all human chromosomes we utilize a set of distinctive ASAR characteristics that allow for the identification of hundreds of autosomal loci with epigenetically controlled, allele-restricted behavior in expression and replication timing of coding and noncoding genes, and is distinct from genomic imprinting. Disruption of noncoding RNA genes at five of five tested loci result in chromosome-wide delayed replication and chromosomal instability, validating their ASAR activity. In addition to the three known essential cis-acting chromosomal loci, origins, centromeres, and telomeres, we propose that all mammalian chromosomes also contain "Inactivation/Stability Centers" that display allele-restricted epigenetic regulation of protein coding and noncoding ASAR genes that are essential for replication and stability of each chromosome.
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Affiliation(s)
- Michael B Heskett
- Stanford Cancer Institute, Stanford University School of Medicine, Stanford, CA, 94305, USA
- Department of Molecular and Medical Genetics Oregon Health & Science University, Portland, OR, 97239, USA
| | - Athanasios E Vouzas
- Department of Biological Science, Florida State University, Tallahassee, FL, 32306, USA
| | - Leslie G Smith
- Department of Chemical Physiology and Biochemistry Oregon Health & Science University, Portland, OR, 97239, USA
| | - Phillip A Yates
- Department of Chemical Physiology and Biochemistry Oregon Health & Science University, Portland, OR, 97239, USA
| | - Christopher Boniface
- Cancer Early Detection Advanced Research Center, Knight Cancer Institute Oregon Health & Science University, Portland, OR, 97239, USA
| | - Eric E Bouhassira
- Department of Cell Biology and Department of Medicine, Albert Einstein College of Medicine, Bronx, NY, 10461, USA
| | - Paul T Spellman
- Department of Molecular and Medical Genetics Oregon Health & Science University, Portland, OR, 97239, USA
- Cancer Early Detection Advanced Research Center, Knight Cancer Institute Oregon Health & Science University, Portland, OR, 97239, USA
| | - David M Gilbert
- San Diego Biomedical Research Institute, San Diego, CA, 92121, USA
| | - Mathew J Thayer
- Department of Chemical Physiology and Biochemistry Oregon Health & Science University, Portland, OR, 97239, USA.
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3
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Kubasova N, Alves-Pereira CF, Gupta S, Vinogradova S, Gimelbrant A, Barreto VM. In Vivo Clonal Analysis Reveals Random Monoallelic Expression in Lymphocytes That Traces Back to Hematopoietic Stem Cells. Front Cell Dev Biol 2022; 10:827774. [PMID: 36003148 PMCID: PMC9393635 DOI: 10.3389/fcell.2022.827774] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Accepted: 05/16/2022] [Indexed: 11/24/2022] Open
Abstract
Evaluating the epigenetic landscape in the stem cell compartment at the single-cell level is essential to assess the cells’ heterogeneity and predict their fate. Here, using a genome-wide transcriptomics approach in vivo, we evaluated the allelic expression imbalance in the progeny of single hematopoietic cells (HSCs) as a read-out of epigenetic marking. After 4 months of extensive proliferation and differentiation, we found that X-chromosome inactivation (XCI) is tightly maintained in all single-HSC derived hematopoietic cells. In contrast, the vast majority of the autosomal genes did not show clonal patterns of random monoallelic expression (RME). However, a persistent allele-specific autosomal transcription in HSCs and their progeny was found in a rare number of cases, none of which has been previously reported. These data show that: 1) XCI and RME in the autosomal chromosomes are driven by different mechanisms; 2) the previously reported high frequency of genes under RME in clones expanded in vitro (up to 15%) is not found in clones undergoing multiple differentiation steps in vivo; 3) prior to differentiation, HSCs have stable patterns of autosomal RME. We propose that most RME patterns in autosomal chromosomes are erased and established de novo during cell lineage differentiation.
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Affiliation(s)
- Nadiya Kubasova
- Chronic Diseases Research Centre, Nova Medical School, CEDOC, Lisbon, Portugal
- Genetagus, Egas Moniz – Cooperativa de Ensino Superior, CRL, Monte de Caparica, Portugal
| | - Clara F. Alves-Pereira
- Center of Cancer Systems Biology, Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA, United States
- Department of Genetics, Harvard Medical School, Boston, MA, United States
- Broad Institute of MIT and Harvard, Cambridge, MA, United States
- Department of Genetics, Smurfit Institute of Genetics, Trinity College Dublin, University of Dublin, Dublin, Ireland
| | - Saumya Gupta
- Center of Cancer Systems Biology, Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA, United States
- Department of Genetics, Harvard Medical School, Boston, MA, United States
- Broad Institute of MIT and Harvard, Cambridge, MA, United States
| | - Svetlana Vinogradova
- Center of Cancer Systems Biology, Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA, United States
- Department of Genetics, Harvard Medical School, Boston, MA, United States
- Broad Institute of MIT and Harvard, Cambridge, MA, United States
| | - Alexander Gimelbrant
- Center of Cancer Systems Biology, Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, MA, United States
- Department of Genetics, Harvard Medical School, Boston, MA, United States
- Broad Institute of MIT and Harvard, Cambridge, MA, United States
- *Correspondence: Vasco M. Barreto, ; Alexander Gimelbrant,
| | - Vasco M. Barreto
- Chronic Diseases Research Centre, Nova Medical School, CEDOC, Lisbon, Portugal
- UCIBIO, Departamento de Ciências da Vida, Faculdade de Ciências e Tecnologia, Universidade NOVA de Lisboa, Costa da Caparica, Portugal
- *Correspondence: Vasco M. Barreto, ; Alexander Gimelbrant,
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4
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Heskett MB, Spellman PT, Thayer MJ. Differential Allelic Expression among Long Non-Coding RNAs. Noncoding RNA 2021; 7:ncrna7040066. [PMID: 34698262 PMCID: PMC8544735 DOI: 10.3390/ncrna7040066] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Revised: 10/11/2021] [Accepted: 10/20/2021] [Indexed: 12/23/2022] Open
Abstract
Long non-coding RNAs (lncRNA) comprise a diverse group of non-protein-coding RNAs >200 bp in length that are involved in various normal cellular processes and disease states, and can affect coding gene expression through mechanisms in cis or in trans. Since the discovery of the first functional lncRNAs transcribed by RNA Polymerase II, H19 and Xist, many others have been identified and noted for their unusual transcriptional pattern, whereby expression from one chromosome homolog is strongly favored over the other, also known as mono-allelic or differential allelic expression. lncRNAs with differential allelic expression have been observed to play critical roles in developmental gene regulation, chromosome structure, and disease. Here, we will focus on known examples of differential allelic expression of lncRNAs and highlight recent research describing functional lncRNAs expressed from both imprinted and random mono-allelic expression domains.
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Affiliation(s)
- Michael B. Heskett
- Department of Genetics, Oregon Health & Science University, Portland, OR 97239, USA; (M.B.H.); (P.T.S.)
| | - Paul T. Spellman
- Department of Genetics, Oregon Health & Science University, Portland, OR 97239, USA; (M.B.H.); (P.T.S.)
| | - Mathew J. Thayer
- Department of Chemical Physiology and Biochemistry, Oregon Health & Science University, Portland, OR 97239, USA
- Correspondence:
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Barreto VM, Kubasova N, Alves-Pereira CF, Gendrel AV. X-Chromosome Inactivation and Autosomal Random Monoallelic Expression as "Faux Amis". Front Cell Dev Biol 2021; 9:740937. [PMID: 34631717 PMCID: PMC8495168 DOI: 10.3389/fcell.2021.740937] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Accepted: 08/30/2021] [Indexed: 12/23/2022] Open
Abstract
X-chromosome inactivation (XCI) and random monoallelic expression of autosomal genes (RMAE) are two paradigms of gene expression regulation where, at the single cell level, genes can be expressed from either the maternal or paternal alleles. X-chromosome inactivation takes place in female marsupial and placental mammals, while RMAE has been described in mammals and also other species. Although the outcome of both processes results in random monoallelic expression and mosaicism at the cellular level, there are many important differences. We provide here a brief sketch of the history behind the discovery of XCI and RMAE. Moreover, we review some of the distinctive features of these two phenomena, with respect to when in development they are established, their roles in dosage compensation and cellular phenotypic diversity, and the molecular mechanisms underlying their initiation and stability.
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Affiliation(s)
- Vasco M Barreto
- Chronic Diseases Research Centre, CEDOC, Nova Medical School, Lisbon, Portugal
| | - Nadiya Kubasova
- Chronic Diseases Research Centre, CEDOC, Nova Medical School, Lisbon, Portugal
| | - Clara F Alves-Pereira
- Department of Genetics, Smurfit Institute of Genetics, Trinity College Dublin, University of Dublin, Dublin, Ireland
| | - Anne-Valerie Gendrel
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina da Universidade de Lisboa, Lisbon, Portugal
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6
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Singh N. Role of mammalian long non-coding RNAs in normal and neuro oncological disorders. Genomics 2021; 113:3250-3273. [PMID: 34302945 DOI: 10.1016/j.ygeno.2021.07.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 07/10/2021] [Accepted: 07/14/2021] [Indexed: 12/09/2022]
Abstract
Long non-coding RNAs (lncRNAs) are expressed at lower levels than protein-coding genes but have a crucial role in gene regulation. LncRNA is distinct, they are being transcribed using RNA polymerase II, and their functionality depends on subcellular localization. Depending on their niche, they specifically interact with DNA, RNA, and proteins and modify chromatin function, regulate transcription at various stages, forms nuclear condensation bodies and nucleolar organization. lncRNAs may also change the stability and translation of cytoplasmic mRNAs and hamper signaling pathways. Thus, lncRNAs affect the physio-pathological states and lead to the development of various disorders, immune responses, and cancer. To date, ~40% of lncRNAs have been reported in the nervous system (NS) and are involved in the early development/differentiation of the NS to synaptogenesis. LncRNA expression patterns in the most common adult and pediatric tumor suggest them as potential biomarkers and provide a rationale for targeting them pharmaceutically. Here, we discuss the mechanisms of lncRNA synthesis, localization, and functions in transcriptional, post-transcriptional, and other forms of gene regulation, methods of lncRNA identification, and their potential therapeutic applications in neuro oncological disorders as explained by molecular mechanisms in other malignant disorders.
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Affiliation(s)
- Neetu Singh
- Molecular Biology Unit, Department of Centre for Advance Research, King George's Medical University, Lucknow, Uttar Pradesh 226 003, India.
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7
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Regulatory and Functional Involvement of Long Non-Coding RNAs in DNA Double-Strand Break Repair Mechanisms. Cells 2021; 10:cells10061506. [PMID: 34203749 PMCID: PMC8232683 DOI: 10.3390/cells10061506] [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: 04/25/2021] [Revised: 06/09/2021] [Accepted: 06/10/2021] [Indexed: 12/12/2022] Open
Abstract
Protection of genome integrity is vital for all living organisms, particularly when DNA double-strand breaks (DSBs) occur. Eukaryotes have developed two main pathways, namely Non-Homologous End Joining (NHEJ) and Homologous Recombination (HR), to repair DSBs. While most of the current research is focused on the role of key protein players in the functional regulation of DSB repair pathways, accumulating evidence has uncovered a novel class of regulating factors termed non-coding RNAs. Non-coding RNAs have been found to hold a pivotal role in the activation of DSB repair mechanisms, thereby safeguarding genomic stability. In particular, long non-coding RNAs (lncRNAs) have begun to emerge as new players with vast therapeutic potential. This review summarizes important advances in the field of lncRNAs, including characterization of recently identified lncRNAs, and their implication in DSB repair pathways in the context of tumorigenesis.
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8
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Chromosomal coordination and differential structure of asynchronous replicating regions. Nat Commun 2021; 12:1035. [PMID: 33589603 PMCID: PMC7884787 DOI: 10.1038/s41467-021-21348-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Accepted: 01/18/2021] [Indexed: 02/05/2023] Open
Abstract
Stochastic asynchronous replication timing (AS-RT) is a phenomenon in which the time of replication of each allele is different, and the identity of the early allele varies between cells. By taking advantage of stable clonal pre-B cell populations derived from C57BL6/Castaneous mice, we have mapped the genome-wide AS-RT loci, independently of genetic differences. These regions are characterized by differential chromatin accessibility, mono-allelic expression and include new gene families involved in specifying cell identity. By combining population level mapping with single cell FISH, our data reveal the existence of a novel regulatory program that coordinates a fixed relationship between AS-RT regions on any given chromosome, with some loci set to replicate in a parallel and others set in the anti-parallel orientation. Our results show that AS-RT is a highly regulated epigenetic mark established during early embryogenesis that may be used for facilitating the programming of mono-allelic choice throughout development. Most regions of the mammalian genome replicate both alleles in a synchronous manner, but some loci have been found to replicate asynchronously and the time of replication of each allele is different. Here the authors, by employing clonal mouse cells from a hybrid strain chart replication timing over the entire genome, using polymorphisms to distinguish between the paternal and maternal alleles.
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9
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Abstract
Evidence accumulated over the past decade shows that long non-coding RNAs (lncRNAs) are widely expressed and have key roles in gene regulation. Recent studies have begun to unravel how the biogenesis of lncRNAs is distinct from that of mRNAs and is linked with their specific subcellular localizations and functions. Depending on their localization and their specific interactions with DNA, RNA and proteins, lncRNAs can modulate chromatin function, regulate the assembly and function of membraneless nuclear bodies, alter the stability and translation of cytoplasmic mRNAs and interfere with signalling pathways. Many of these functions ultimately affect gene expression in diverse biological and physiopathological contexts, such as in neuronal disorders, immune responses and cancer. Tissue-specific and condition-specific expression patterns suggest that lncRNAs are potential biomarkers and provide a rationale to target them clinically. In this Review, we discuss the mechanisms of lncRNA biogenesis, localization and functions in transcriptional, post-transcriptional and other modes of gene regulation, and their potential therapeutic applications.
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10
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Kantidze OL, Razin SV. Weak interactions in higher-order chromatin organization. Nucleic Acids Res 2020; 48:4614-4626. [PMID: 32313950 PMCID: PMC7229822 DOI: 10.1093/nar/gkaa261] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Revised: 03/30/2020] [Accepted: 04/03/2020] [Indexed: 12/20/2022] Open
Abstract
The detailed principles of the hierarchical folding of eukaryotic chromosomes have been revealed during the last two decades. Along with structures composing three-dimensional (3D) genome organization (chromatin compartments, topologically associating domains, chromatin loops, etc.), the molecular mechanisms that are involved in their establishment and maintenance have been characterized. Generally, protein-protein and protein-DNA interactions underlie the spatial genome organization in eukaryotes. However, it is becoming increasingly evident that weak interactions, which exist in biological systems, also contribute to the 3D genome. Here, we provide a snapshot of our current understanding of the role of the weak interactions in the establishment and maintenance of the 3D genome organization. We discuss how weak biological forces, such as entropic forces operating in crowded solutions, electrostatic interactions of the biomolecules, liquid-liquid phase separation, DNA supercoiling, and RNA environment participate in chromosome segregation into structural and functional units and drive intranuclear functional compartmentalization.
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Affiliation(s)
- Omar L Kantidze
- Institute of Gene Biology Russian Academy of Sciences, 119334 Moscow, Russia
| | - Sergey V Razin
- Institute of Gene Biology Russian Academy of Sciences, 119334 Moscow, Russia
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11
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Heskett MB, Smith LG, Spellman P, Thayer MJ. Reciprocal monoallelic expression of ASAR lncRNA genes controls replication timing of human chromosome 6. RNA (NEW YORK, N.Y.) 2020; 26:724-738. [PMID: 32144193 PMCID: PMC7266157 DOI: 10.1261/rna.073114.119] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/26/2019] [Accepted: 02/22/2020] [Indexed: 06/10/2023]
Abstract
DNA replication occurs on mammalian chromosomes in a cell-type distinctive temporal order known as the replication timing program. We previously found that disruption of the noncanonical lncRNA genes ASAR6 and ASAR15 results in delayed replication timing and delayed mitotic chromosome condensation of human chromosomes 6 and 15, respectively. ASAR6 and ASAR15 display random monoallelic expression and display asynchronous replication between alleles that is coordinated with other random monoallelic genes on their respective chromosomes. Disruption of the expressed allele, but not the silent allele, of ASAR6 leads to delayed replication, activation of the previously silent alleles of linked monoallelic genes, and structural instability of human chromosome 6. In this report, we describe a second lncRNA gene (ASAR6-141) on human chromosome 6 that when disrupted results in delayed replication timing in cisASAR6-141 is subject to random monoallelic expression and asynchronous replication and is expressed from the opposite chromosome 6 homolog as ASAR6 ASAR6-141 RNA, like ASAR6 and ASAR15 RNAs, contains a high L1 content and remains associated with the chromosome territory where it is transcribed. Three classes of cis-acting elements control proper chromosome function in mammals: origins of replication, centromeres, and telomeres, which are responsible for replication, segregation, and stability of all chromosomes. Our work supports a fourth type of essential chromosomal element, the "Inactivation/Stability Center," which expresses ASAR lncRNAs responsible for proper replication timing, monoallelic expression, and structural stability of each chromosome.
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Affiliation(s)
- Michael B Heskett
- Department of Molecular and Medical Genetics, Oregon Health & Science University, Portland, Oregon 97239, USA
| | - Leslie G Smith
- Department of Chemical Physiology and Biochemistry, Oregon Health & Science University, Portland, Oregon 97239, USA
| | - Paul Spellman
- Department of Molecular and Medical Genetics, Oregon Health & Science University, Portland, Oregon 97239, USA
| | - Mathew J Thayer
- Department of Chemical Physiology and Biochemistry, Oregon Health & Science University, Portland, Oregon 97239, USA
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12
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Control of DNA replication timing in the 3D genome. Nat Rev Mol Cell Biol 2019; 20:721-737. [DOI: 10.1038/s41580-019-0162-y] [Citation(s) in RCA: 134] [Impact Index Per Article: 26.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/18/2019] [Indexed: 12/27/2022]
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13
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Rivera-Mulia JC, Kim S, Gabr H, Chakraborty A, Ay F, Kahveci T, Gilbert DM. Replication timing networks reveal a link between transcription regulatory circuits and replication timing control. Genome Res 2019; 29:1415-1428. [PMID: 31434679 PMCID: PMC6724675 DOI: 10.1101/gr.247049.118] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2018] [Accepted: 08/05/2019] [Indexed: 12/11/2022]
Abstract
DNA replication occurs in a defined temporal order known as the replication timing (RT) program and is regulated during development, coordinated with 3D genome organization and transcriptional activity. However, transcription and RT are not sufficiently coordinated to predict each other, suggesting an indirect relationship. Here, we exploit genome-wide RT profiles from 15 human cell types and intermediate differentiation stages derived from human embryonic stem cells to construct different types of RT regulatory networks. First, we constructed networks based on the coordinated RT changes during cell fate commitment to create highly complex RT networks composed of thousands of interactions that form specific functional subnetwork communities. We also constructed directional regulatory networks based on the order of RT changes within cell lineages, and identified master regulators of differentiation pathways. Finally, we explored relationships between RT networks and transcriptional regulatory networks (TRNs) by combining them into more complex circuitries of composite and bipartite networks. Results identified novel trans interactions linking transcription factors that are core to the regulatory circuitry of each cell type to RT changes occurring in those cell types. These core transcription factors were found to bind cooperatively to sites in the affected replication domains, providing provocative evidence that they constitute biologically significant directional interactions. Our findings suggest a regulatory link between the establishment of cell-type-specific TRNs and RT control during lineage specification.
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Affiliation(s)
- Juan Carlos Rivera-Mulia
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota Medical School, Minneapolis, Minnesota 55455, USA
| | - Sebo Kim
- Department of Computer and Information Sciences and Engineering, University of Florida, Gainesville, Florida 32611, USA
| | - Haitham Gabr
- Department of Computer and Information Sciences and Engineering, University of Florida, Gainesville, Florida 32611, USA
| | - Abhijit Chakraborty
- La Jolla Institute for Allergy and Immunology, La Jolla, California 92037, USA
| | - Ferhat Ay
- La Jolla Institute for Allergy and Immunology, La Jolla, California 92037, USA
- School of Medicine, University of California San Diego, La Jolla, California 92093, USA
| | - Tamer Kahveci
- Department of Computer and Information Sciences and Engineering, University of Florida, Gainesville, Florida 32611, USA
| | - David M Gilbert
- Department of Biological Science, Florida State University, Tallahassee, Florida, 32306-4295, USA
- Center for Genomics and Personalized Medicine, Florida State University, Tallahassee, Florida 32306, USA
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14
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O'Neill RJ, O'Neill MJ. Replication timing kept in LINE. J Cell Biol 2018; 217:441-443. [PMID: 29348148 PMCID: PMC5800820 DOI: 10.1083/jcb.201712173] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022] Open
Abstract
O'Neill and O'Neill discuss Platt et al.’s findings that LINE1 elements are key to control of replication timing by ASAR long noncoding RNAs. Accurate and synchronous replication timing between chromosome homologues is essential for maintaining chromosome stability, yet how this is achieved has remained a mystery. In this issue, Platt et al. (2018. J. Cell Biol.https://doi.org/10.1083/jcb.201707082) identify antisense LINE (L1) transcripts within long noncoding RNAs as the critical factor in maintaining synchronous chromosome-wide replication timing.
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Affiliation(s)
- Rachel J O'Neill
- Institute for Systems Genomics, University of Connecticut, Storrs, CT .,Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT
| | - Michael J O'Neill
- Institute for Systems Genomics, University of Connecticut, Storrs, CT.,Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT
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15
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Platt EJ, Smith L, Thayer MJ. L1 retrotransposon antisense RNA within ASAR lncRNAs controls chromosome-wide replication timing. J Cell Biol 2017; 217:541-553. [PMID: 29288153 PMCID: PMC5800813 DOI: 10.1083/jcb.201707082] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2017] [Revised: 09/19/2017] [Accepted: 11/27/2017] [Indexed: 12/11/2022] Open
Abstract
Proper chromosome duplication is critical for genome integrity and normal cellular function. Platt et al. show that the lncRNA genes ASAR6 and ASAR15 control chromosome-wide replication timing via the antisense strand of L1 retrotransposons located within ASAR6 and ASAR15 RNAs. Mammalian cells replicate their chromosomes via a temporal replication program. The ASAR6 and ASAR15 genes were identified as loci that when disrupted result in delayed replication and condensation of entire human chromosomes. ASAR6 and ASAR15 are monoallelically expressed long noncoding RNAs that remain associated with the chromosome from which they are transcribed. The chromosome-wide effects of ASAR6 map to the antisense strand of an L1 retrotransposon within ASAR6 RNA, deletion or inversion of which delayed replication of human chromosome 6. Furthermore, ectopic integration of ASAR6 or ASAR15 transgenes into mouse chromosomes resulted in delayed replication and condensation, an increase in H3K27me3, coating of the mouse chromosome with ASAR RNA, and a loss of mouse Cot-1 RNA expression in cis. Targeting the antisense strand of the L1 within ectopically expressed ASAR6 RNA restored normal replication timing. Our results provide direct evidence that L1 antisense RNA plays a functional role in chromosome-wide replication timing of mammalian chromosomes.
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Affiliation(s)
- Emily J Platt
- Department of Biochemistry and Molecular Biology, Oregon Health & Science University, Portland, OR
| | - Leslie Smith
- Department of Biochemistry and Molecular Biology, Oregon Health & Science University, Portland, OR
| | - Mathew J Thayer
- Department of Biochemistry and Molecular Biology, Oregon Health & Science University, Portland, OR
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16
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Programming asynchronous replication in stem cells. Nat Struct Mol Biol 2017; 24:1132-1138. [PMID: 29131141 DOI: 10.1038/nsmb.3503] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Accepted: 10/12/2017] [Indexed: 01/12/2023]
Abstract
Many regions of the genome replicate asynchronously and are expressed monoallelically. It is thought that asynchronous replication may be involved in choosing one allele over the other, but little is known about how these patterns are established during development. We show that, unlike somatic cells, which replicate in a clonal manner, embryonic and adult stem cells are programmed to undergo switching, such that daughter cells with an early-replicating paternal allele are derived from mother cells that have a late-replicating paternal allele. Furthermore, using ground-state embryonic stem (ES) cells, we demonstrate that in the initial transition to asynchronous replication, it is always the paternal allele that is chosen to replicate early, suggesting that primary allelic choice is directed by preset gametic DNA markers. Taken together, these studies help define a basic general strategy for establishing allelic discrimination and generating allelic diversity throughout the organism.
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17
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Abstract
Monoallelic expression not due to cis-regulatory sequence polymorphism poses an intriguing problem in epigenetics because it requires the unequal treatment of two segments of DNA that are present in the same nucleus and that can indeed have absolutely identical sequences. Here, I focus on a few recent developments in the field of monoallelic expression that are of particular interest and raise interesting questions for future work. One development is regarding analyses of imprinted genes, in which recent work suggests the possibility that intriguing networks of imprinted genes exist and are important for genetic and physiological studies. Another issue that has been raised in recent years by a number of publications is the question of how skewed allelic expression should be for it to be designated as monoallelic expression and, further, what methods are appropriate or inappropriate for analyzing genomic data to examine allele-specific expression. Perhaps the most exciting recent development in mammalian monoallelic expression is a clever and carefully executed analysis of genetic diversity of autosomal genes subject to random monoallelic expression (RMAE), which provides compelling evidence for distinct evolutionary forces acting on random monoallelically expressed genes.
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Affiliation(s)
- Andrew Chess
- Department of Genetics and Genomic Sciences, Department of Developmental and Regenerative Biology, Fishberg Department of Neuroscience, and Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029-6574;
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18
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Magne F, Ge B, Larrivée-Vanier S, Van Vliet G, Samuels ME, Pastinen T, Deladoëy J. Demonstration of Autosomal Monoallelic Expression in Thyroid Tissue Assessed by Whole-Exome and Bulk RNA Sequencing. Thyroid 2016; 26:852-9. [PMID: 27125219 DOI: 10.1089/thy.2016.0009] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
BACKGROUND Congenital hypothyroidism due to thyroid dysgenesis (CHTD) is a disorder with a prevalence of 1/4000 live births, the cause of which remains unknown. The most common diagnostic category is thyroid ectopy, which occurs in up to 80% of CHTD cases. CHTD is predominantly not inherited and has a high discordance rate (>92%) between monozygotic (MZ) twins. The sporadic nature of CHTD might be explained by somatic events such as autosomal monoallelic expression (AME), given that genes expressed in a monoallelic way are more vulnerable to otherwise benign monoallelict genetic or epigenetic mutations. OBJECTIVE The aim of this study was to search for complete (90%) AME in normal and dysgenetic thyroid tissues. METHODS Aggregated analysis of whole-exome and bulk RNA sequencing was performed on two ectopic thyroids, four normal thyroids, and the human thyroid cell line Nthy-ori. RESULTS A median of 5062 (range 2081-5270) genes per sample showed sufficient numbers of heterozygous single nucleotide polymorphisms to be informative. The median monoallelic expression represented 22 (range 16-32) of the informative genes for each thyroid sample. Examples of genes displaying AME are FCGBP, ZNF331, USP10, BCLAF1, and some HLA genes; these genes are involved in epithelial-mesenchymal transition, cell migration, cancer, and immunity. CONCLUSIONS AME may account for the high discordance rate observed between MZ twins and for the sporadic nature of CHTD. These findings also have implications for other pathologies, including cancers and autoimmune disorders of the thyroid.
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Affiliation(s)
- Fabien Magne
- 1 Endocrinology Service and Research Center, Sainte-Justine University Hospital Center, Department of Pediatrics, Université de Montréal , Montreal, Canada
- 2 Department of Biomedical Sciences, Université de Montréal , Montreal, Canada
| | - Bing Ge
- 3 Department of Human Genetics, McGill University , Montreal, Canada
| | - Stéphanie Larrivée-Vanier
- 1 Endocrinology Service and Research Center, Sainte-Justine University Hospital Center, Department of Pediatrics, Université de Montréal , Montreal, Canada
| | - Guy Van Vliet
- 1 Endocrinology Service and Research Center, Sainte-Justine University Hospital Center, Department of Pediatrics, Université de Montréal , Montreal, Canada
| | - Mark E Samuels
- 1 Endocrinology Service and Research Center, Sainte-Justine University Hospital Center, Department of Pediatrics, Université de Montréal , Montreal, Canada
- 4 Department of Medicine, Université de Montréal , Montreal, Canada
| | - Tomi Pastinen
- 3 Department of Human Genetics, McGill University , Montreal, Canada
| | - Johnny Deladoëy
- 1 Endocrinology Service and Research Center, Sainte-Justine University Hospital Center, Department of Pediatrics, Université de Montréal , Montreal, Canada
- 2 Department of Biomedical Sciences, Université de Montréal , Montreal, Canada
- 5 Department of Biochemistry, Université de Montréal , Montreal, Canada
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19
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Rivera-Mulia JC, Gilbert DM. Replication timing and transcriptional control: beyond cause and effect-part III. Curr Opin Cell Biol 2016; 40:168-178. [PMID: 27115331 DOI: 10.1016/j.ceb.2016.03.022] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2015] [Revised: 03/24/2016] [Accepted: 03/29/2016] [Indexed: 11/17/2022]
Abstract
DNA replication is essential for faithful transmission of genetic information and is intimately tied to chromosome structure and function. Genome duplication occurs in a defined temporal order known as the replication-timing (RT) program, which is regulated during the cell cycle and development in discrete units referred to as replication domains (RDs). RDs correspond to topologically-associating domains (TADs) and are spatio-temporally compartmentalized in the nucleus. While improvements in experimental tools have begun to reveal glimpses of causality, they have also unveiled complex context-dependent relationships that challenge long recognized correlations of RT to chromatin organization and gene regulation. In particular, RDs/TADs that switch RT during development march to the beat of a different drummer.
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Affiliation(s)
| | - David M Gilbert
- Department of Biological Science, Florida State University, Tallahassee, FL 32306-4295, USA; Center for Genomics and Personalized Medicine, Florida State University, Tallahassee, FL, USA.
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20
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Gendrel AV, Marion-Poll L, Katoh K, Heard E. Random monoallelic expression of genes on autosomes: Parallels with X-chromosome inactivation. Semin Cell Dev Biol 2016; 56:100-110. [PMID: 27101886 DOI: 10.1016/j.semcdb.2016.04.007] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Revised: 04/08/2016] [Accepted: 04/15/2016] [Indexed: 01/04/2023]
Abstract
Genes are generally expressed from their two alleles, except in some particular cases such as random inactivation of one of the two X chromosomes in female mammals or imprinted genes which are expressed only from the maternal or the paternal allele. A lesser-known phenomenon is random monoallelic expression (RME) of autosomal genes, where genes can be stably expressed in a monoallelic manner, from either one of the parental alleles. Studies on autosomal RME face several challenges. First, RME that is based on epigenetic mechanisms has to be distinguished from biased expression of one allele caused by a DNA sequence polymorphism in a regulatory element. Second, RME should not be confused with transient monoallelic expression often observed in single cell analyses, and that often corresponds to dynamic bursting of expression. Thanks to analyses on clonal cell populations, the existence of RME in cultured cells is now well established. Future studies of RME in vivo will have to overcome tissue heterogeneity and certain technical limitations. Here, we discuss current knowledge on autosomal RME, as well as possible mechanisms controlling these expression patterns and potential implications for development and disease, drawing parallels with what is known for X-chromosome inactivation, a paradigm of random monoallelic expression.
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Affiliation(s)
- Anne-Valerie Gendrel
- Institut Curie, PSL Research University, CNRS UMR 3215, INSERM U934, Mammalian Developmental Epigenetics group, F-75005 Paris, France; Sorbonne Universités, UPMC Univ Paris 6, F-75005 Paris, France.
| | - Lucile Marion-Poll
- Institut Curie, PSL Research University, CNRS UMR 3215, INSERM U934, Mammalian Developmental Epigenetics group, F-75005 Paris, France; Sorbonne Universités, UPMC Univ Paris 6, F-75005 Paris, France
| | - Kimiko Katoh
- Institut Curie, PSL Research University, CNRS UMR 3215, INSERM U934, Mammalian Developmental Epigenetics group, F-75005 Paris, France; Sorbonne Universités, UPMC Univ Paris 6, F-75005 Paris, France
| | - Edith Heard
- Institut Curie, PSL Research University, CNRS UMR 3215, INSERM U934, Mammalian Developmental Epigenetics group, F-75005 Paris, France; Sorbonne Universités, UPMC Univ Paris 6, F-75005 Paris, France.
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21
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Rivera-Mulia JC, Buckley Q, Sasaki T, Zimmerman J, Didier RA, Nazor K, Loring JF, Lian Z, Weissman S, Robins AJ, Schulz TC, Menendez L, Kulik MJ, Dalton S, Gabr H, Kahveci T, Gilbert DM. Dynamic changes in replication timing and gene expression during lineage specification of human pluripotent stem cells. Genome Res 2015; 25:1091-103. [PMID: 26055160 PMCID: PMC4509994 DOI: 10.1101/gr.187989.114] [Citation(s) in RCA: 105] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Accepted: 06/05/2015] [Indexed: 12/31/2022]
Abstract
Duplication of the genome in mammalian cells occurs in a defined temporal order referred to as its replication-timing (RT) program. RT changes dynamically during development, regulated in units of 400-800 kb referred to as replication domains (RDs). Changes in RT are generally coordinated with transcriptional competence and changes in subnuclear position. We generated genome-wide RT profiles for 26 distinct human cell types, including embryonic stem cell (hESC)-derived, primary cells and established cell lines representing intermediate stages of endoderm, mesoderm, ectoderm, and neural crest (NC) development. We identified clusters of RDs that replicate at unique times in each stage (RT signatures) and confirmed global consolidation of the genome into larger synchronously replicating segments during differentiation. Surprisingly, transcriptome data revealed that the well-accepted correlation between early replication and transcriptional activity was restricted to RT-constitutive genes, whereas two-thirds of the genes that switched RT during differentiation were strongly expressed when late replicating in one or more cell types. Closer inspection revealed that transcription of this class of genes was frequently restricted to the lineage in which the RT switch occurred, but was induced prior to a late-to-early RT switch and/or down-regulated after an early-to-late RT switch. Analysis of transcriptional regulatory networks showed that this class of genes contains strong regulators of genes that were only expressed when early replicating. These results provide intriguing new insight into the complex relationship between transcription and RT regulation during human development.
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Affiliation(s)
- Juan Carlos Rivera-Mulia
- Department of Biological Science, Florida State University, Tallahassee, Florida 32306-4295, USA
| | - Quinton Buckley
- Department of Biological Science, Florida State University, Tallahassee, Florida 32306-4295, USA
| | - Takayo Sasaki
- Department of Biological Science, Florida State University, Tallahassee, Florida 32306-4295, USA
| | - Jared Zimmerman
- Department of Biological Science, Florida State University, Tallahassee, Florida 32306-4295, USA
| | - Ruth A Didier
- College of Medicine, Florida State University, Tallahassee, Florida 32306-4295, USA
| | - Kristopher Nazor
- Center for Regenerative Medicine, Department of Chemical Physiology, The Scripps Research Institute, La Jolla, California 92037, USA
| | - Jeanne F Loring
- Center for Regenerative Medicine, Department of Chemical Physiology, The Scripps Research Institute, La Jolla, California 92037, USA
| | - Zheng Lian
- Department of Genetics, Yale University School of Medicine, New Haven, Connecticut 06519, USA
| | - Sherman Weissman
- Department of Genetics, Yale University School of Medicine, New Haven, Connecticut 06519, USA
| | | | | | - Laura Menendez
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia 30602, USA
| | - Michael J Kulik
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia 30602, USA
| | - Stephen Dalton
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia 30602, USA
| | - Haitham Gabr
- Department of Computer and Information Sciences and Engineering, University of Florida, Gainesville, Florida 32611, USA
| | - Tamer Kahveci
- Department of Computer and Information Sciences and Engineering, University of Florida, Gainesville, Florida 32611, USA
| | - David M Gilbert
- Department of Biological Science, Florida State University, Tallahassee, Florida 32306-4295, USA; Center for Genomics and Personalized Medicine, Florida State University, Tallahassee, Florida 32306, USA
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22
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Nicholson JM, Cimini D. Link between aneuploidy and chromosome instability. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2015; 315:299-317. [PMID: 25708466 DOI: 10.1016/bs.ircmb.2014.11.002] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Aneuploidy is widely acknowledged as a leading cause of miscarriage and birth defects in humans, and is generally known to be deleterious to the survival of individual cells. However, aneuploidy is also ubiquitous in cancer and is found to arise as an adaptive response in certain contexts. This dichotomy of aneuploidy has attracted the interest of researchers for over a century, but many studies have reached conflicting conclusions. The emergence of new technology has allowed scientists to revisit the aneuploidy problem and has fueled a number of recent studies aimed at understanding the effects of aneuploidy on cell physiology. Here, we review these studies, in light of previous observations and knowledge, specifically focusing on the effects of aneuploidy on cellular homeostasis, chromosome stability, and adaptation.
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Affiliation(s)
- Joshua M Nicholson
- Department of Biological Sciences and Virginia Bioinformatics Institute, Virginia Tech, Blacksburg, VA, USA
| | - Daniela Cimini
- Department of Biological Sciences and Virginia Bioinformatics Institute, Virginia Tech, Blacksburg, VA, USA
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23
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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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24
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Koren A. DNA replication timing: Coordinating genome stability with genome regulation on the X chromosome and beyond. Bioessays 2014; 36:997-1004. [PMID: 25138663 DOI: 10.1002/bies.201400077] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Recent studies based on next-generation DNA sequencing have revealed that the female inactive X chromosome is replicated in a rapid, unorganized manner, and undergoes increased rates of mutation. These observations link the organization of DNA replication timing to gene regulation on one hand, and to the generation of mutations on the other hand. More generally, the exceptional biology of the inactive X chromosome highlights general principles of genome replication. Cells may control replication timing by a combination of intrinsic replication origin properties, local chromatin states and global levels of replication factors, leading to a functional separation between the activity of genes and their mutation.
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Affiliation(s)
- Amnon Koren
- Department of Genetics, Harvard Medical School, Boston, MA, USA; Program in Medical and Population Genetics, Broad Institute of MIT and Harvard, Cambridge, MA, USA
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25
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Smith OK, Aladjem MI. Chromatin structure and replication origins: determinants of chromosome replication and nuclear organization. J Mol Biol 2014; 426:3330-41. [PMID: 24905010 DOI: 10.1016/j.jmb.2014.05.027] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2014] [Revised: 05/22/2014] [Accepted: 05/24/2014] [Indexed: 12/29/2022]
Abstract
The DNA replication program is, in part, determined by the epigenetic landscape that governs local chromosome architecture and directs chromosome duplication. Replication must coordinate with other biochemical processes occurring concomitantly on chromatin, such as transcription and remodeling, to insure accurate duplication of both genetic and epigenetic features and to preserve genomic stability. The importance of genome architecture and chromatin looping in coordinating cellular processes on chromatin is illustrated by two recent sets of discoveries. First, chromatin-associated proteins that are not part of the core replication machinery were shown to affect the timing of DNA replication. These chromatin-associated proteins could be working in concert, or perhaps in competition, with the transcriptional machinery and with chromatin modifiers to determine the spatial and temporal organization of replication initiation events. Second, epigenetic interactions are mediated by DNA sequences that determine chromosomal replication. In this review, we summarize recent findings and current models linking spatial and temporal regulation of the replication program with epigenetic signaling. We discuss these issues in the context of the genome's three-dimensional structure with an emphasis on events occurring during the initiation of DNA replication.
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Affiliation(s)
- Owen K Smith
- DNA Replication Group, Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD 20892, USA
| | - Mirit I Aladjem
- DNA Replication Group, Developmental Therapeutics Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD 20892, USA.
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26
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Mukhopadhyay R, Lajugie J, Fourel N, Selzer A, Schizas M, Bartholdy B, Mar J, Lin CM, Martin MM, Ryan M, Aladjem MI, Bouhassira EE. Allele-specific genome-wide profiling in human primary erythroblasts reveal replication program organization. PLoS Genet 2014; 10:e1004319. [PMID: 24787348 PMCID: PMC4006724 DOI: 10.1371/journal.pgen.1004319] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2013] [Accepted: 03/10/2014] [Indexed: 11/19/2022] Open
Abstract
We have developed a new approach to characterize allele-specific timing of DNA replication genome-wide in human primary basophilic erythroblasts. We show that the two chromosome homologs replicate at the same time in about 88% of the genome and that large structural variants are preferentially associated with asynchronous replication. We identified about 600 megabase-sized asynchronously replicated domains in two tested individuals. The longest asynchronously replicated domains are enriched in imprinted genes suggesting that structural variants and parental imprinting are two causes of replication asynchrony in the human genome. Biased chromosome X inactivation in one of the two individuals tested was another source of detectable replication asynchrony. Analysis of high-resolution TimEX profiles revealed small variations termed timing ripples, which were undetected in previous, lower resolution analyses. Timing ripples reflect highly reproducible, variations of the timing of replication in the 100 kb-range that exist within the well-characterized megabase-sized replication timing domains. These ripples correspond to clusters of origins of replication that we detected using novel nascent strands DNA profiling methods. Analysis of the distribution of replication origins revealed dramatic differences in initiation of replication frequencies during S phase and a strong association, in both synchronous and asynchronous regions, between origins of replication and three genomic features: G-quadruplexes, CpG Islands and transcription start sites. The frequency of initiation in asynchronous regions was similar in the two homologs. Asynchronous regions were richer in origins of replication than synchronous regions. DNA replication in mammalian cells proceeds according to a distinct order. Genes that are expressed tend to replicate before genes that are not expressed. We report here that we have developed a method to measure the timing of replication of the maternal and paternal chromosomes separately. We found that the paternal and maternal chromosomes replicate at exactly the same time in the large majority of the genome and that the 12% of the genome that replicated asynchronously was enriched in imprinted genes and in structural variants. Previous experiments have shown that chromosomes could be divided into replication timing domains that are a few hundred thousand to a few megabases in size. We show here that these domains can be divided into sub-domains defined by ripples in the timing profile. These ripples corresponded to clusters of origins of replication. Finally, we show that the frequency of initiation in asynchronous regions was similar in the two homologs.
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Affiliation(s)
- Rituparna Mukhopadhyay
- Department of Cell Biology, Albert Einstein College of Medicine, Bronx, New York, United States of America
| | - Julien Lajugie
- Department of Cell Biology, Albert Einstein College of Medicine, Bronx, New York, United States of America
| | - Nicolas Fourel
- Department of Cell Biology, Albert Einstein College of Medicine, Bronx, New York, United States of America
| | - Ari Selzer
- Department of Cell Biology, Albert Einstein College of Medicine, Bronx, New York, United States of America
| | - Michael Schizas
- Department of Cell Biology, Albert Einstein College of Medicine, Bronx, New York, United States of America
| | - Boris Bartholdy
- Department of Cell Biology, Albert Einstein College of Medicine, Bronx, New York, United States of America
| | - Jessica Mar
- Department of Systems and Computational Biology, Albert Einstein College of Medicine, Bronx, New York, United States of America
| | - Chii Mei Lin
- Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland, United States of America
| | - Melvenia M. Martin
- Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland, United States of America
| | - Michael Ryan
- Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland, United States of America
| | - Mirit I. Aladjem
- Laboratory of Molecular Pharmacology, Center for Cancer Research, National Cancer Institute, Bethesda, Maryland, United States of America
| | - Eric E. Bouhassira
- Department of Cell Biology, Albert Einstein College of Medicine, Bronx, New York, United States of America
- * E-mail:
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27
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Eckersley-Maslin MA, Spector DL. Random monoallelic expression: regulating gene expression one allele at a time. Trends Genet 2014; 30:237-44. [PMID: 24780084 DOI: 10.1016/j.tig.2014.03.003] [Citation(s) in RCA: 74] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2014] [Revised: 03/24/2014] [Accepted: 03/25/2014] [Indexed: 10/25/2022]
Abstract
Monoallelic gene expression is a remarkable process in which transcription occurs from only one of two homologous alleles in a diploid cell. Interestingly, between 0.5% and 15% of autosomal genes exhibit random monoallelic gene expression, in which different cells express only one allele independently of the underlying genomic sequence, in a cell type-specific manner. Recently, genome-wide studies have increased our understanding of the cell type-specific incidence of random monoallelic gene expression, and how the imbalance in allelic expression is distinguished within the cell and potentially maintained across cell generations. Monoallelic gene expression is likely generated through stochastic independent regulation of the two alleles upon differentiation, and has varied implications for the cell and organism, in particular with respect to disease.
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Affiliation(s)
- Mélanie A Eckersley-Maslin
- Watson School of Biological Sciences, Cold Spring Harbor Laboratory, One Bungtown Road, Cold Spring Harbor, NY 11724, USA
| | - David L Spector
- Watson School of Biological Sciences, Cold Spring Harbor Laboratory, One Bungtown Road, Cold Spring Harbor, NY 11724, USA.
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28
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Abstract
While large portions of the mammalian genome are known to replicate sequentially in a distinct, tissue-specific order, recent studies suggest that the inactive X chromosome is duplicated rapidly via random, synchronous DNA synthesis at numerous adjacent regions. The rapid duplication of the inactive X chromosome was observed in high-resolution studies visualizing DNA replication patterns in the nucleus, and by allele-specific DNA sequencing studies measuring the extent of DNA synthesis. These studies conclude that inactive X chromosomes complete replication earlier than previously thought and suggest that the strict order of DNA replication detected in the majority of genomic regions is not preserved in non-transcribed, "silent" chromatin. These observations alter current concepts about the regulation of DNA replication in non-transcribed portions of the genome in general and in the inactive X-chromosome in particular.
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Affiliation(s)
- Mirit I Aladjem
- Developmental Therapeutic Branch, Center for Cancer Research, National Cancer Institute, Bethesda, MD, USA
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29
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Eckersley-Maslin MA, Thybert D, Bergmann JH, Marioni JC, Flicek P, Spector DL. Random monoallelic gene expression increases upon embryonic stem cell differentiation. Dev Cell 2014; 28:351-65. [PMID: 24576421 PMCID: PMC3955261 DOI: 10.1016/j.devcel.2014.01.017] [Citation(s) in RCA: 92] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2013] [Revised: 12/21/2013] [Accepted: 01/21/2014] [Indexed: 11/23/2022]
Abstract
Random autosomal monoallelic gene expression refers to the transcription of a gene from one of two homologous alleles. We assessed the dynamics of monoallelic expression during development through an allele-specific RNA-sequencing screen in clonal populations of hybrid mouse embryonic stem cells (ESCs) and neural progenitor cells (NPCs). We identified 67 and 376 inheritable autosomal random monoallelically expressed genes in ESCs and NPCs, respectively, a 5.6-fold increase upon differentiation. Although DNA methylation and nuclear positioning did not distinguish the active and inactive alleles, specific histone modifications were differentially enriched between the two alleles. Interestingly, expression levels of 8% of the monoallelically expressed genes remained similar between monoallelic and biallelic clones. These results support a model in which random monoallelic expression occurs stochastically during differentiation and, for some genes, is compensated for by the cell to maintain the required transcriptional output of these genes.
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Affiliation(s)
- Mélanie A Eckersley-Maslin
- Cold Spring Harbor Laboratory, One Bungtown Road, Cold Spring Harbor, NY 11724, USA; Watson School of Biological Sciences, Cold Spring Harbor Laboratory, One Bungtown Road, Cold Spring Harbor, NY 11724, USA
| | - David Thybert
- European Molecular Biology Laboratory, European Bioinformatics Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge CB10 1SD, UK
| | - Jan H Bergmann
- Cold Spring Harbor Laboratory, One Bungtown Road, Cold Spring Harbor, NY 11724, USA
| | - John C Marioni
- European Molecular Biology Laboratory, European Bioinformatics Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge CB10 1SD, UK
| | - Paul Flicek
- European Molecular Biology Laboratory, European Bioinformatics Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge CB10 1SD, UK
| | - David L Spector
- Cold Spring Harbor Laboratory, One Bungtown Road, Cold Spring Harbor, NY 11724, USA; Watson School of Biological Sciences, Cold Spring Harbor Laboratory, One Bungtown Road, Cold Spring Harbor, NY 11724, USA.
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30
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Savova V, Vigneau S, Gimelbrant AA. Autosomal monoallelic expression: genetics of epigenetic diversity? Curr Opin Genet Dev 2013; 23:642-8. [PMID: 24075575 DOI: 10.1016/j.gde.2013.09.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2013] [Revised: 09/03/2013] [Accepted: 09/04/2013] [Indexed: 11/17/2022]
Abstract
In mammals, relative expression of the two parental alleles of many genes is controlled by one of three major epigenetic phenomena: X chromosome inactivation, imprinting, and mitotically stable autosomal monoallelic expression (MAE). MAE affects a large fraction of human autosomal genes and introduces enormous epigenetic heterogeneity in otherwise similar cell populations. Despite its prevalence, many functional and mechanistic aspects of MAE biology remain unknown. Several lines of evidence imply that MAE establishment and maintenance are controlled by a variety of genetic elements. Based on known genomic features regulating X-inactivation and imprinting, we outline likely features of MAE-controlling elements. We also assess implications of MAE for genotype-phenotype relationship, with a focus on haploinsufficiency.
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Affiliation(s)
- Virginia Savova
- Department of Cancer Biology, Dana-Farber Cancer Institute, Department of Genetics, Harvard Medical School, 450 Brookline Avenue, Boston, MA 02215, United States
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31
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Nicholson JM, Cimini D. Cancer karyotypes: survival of the fittest. Front Oncol 2013; 3:148. [PMID: 23760367 PMCID: PMC3675379 DOI: 10.3389/fonc.2013.00148] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2013] [Accepted: 05/22/2013] [Indexed: 11/13/2022] Open
Abstract
Cancer cells are typically characterized by complex karyotypes including both structural and numerical changes, with aneuploidy being a ubiquitous feature. It is becoming increasingly evident that aneuploidy per se can cause chromosome mis-segregation, which explains the higher rates of chromosome gain/loss observed in aneuploid cancer cells compared to normal diploid cells, a phenotype termed chromosomal instability (CIN). CIN can be caused by various mechanisms and results in extensive karyotypic heterogeneity within a cancer cell population. However, despite such karyotypic heterogeneity, cancer cells also display predominant karyotypic patterns. In this review we discuss the mechanisms of CIN, with particular emphasis on the role of aneuploidy on CIN. Further, we discuss the potential functional role of karyotypic patterns in cancer.
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Pope BD, Gilbert DM. The replication domain model: regulating replicon firing in the context of large-scale chromosome architecture. J Mol Biol 2013; 425:4690-5. [PMID: 23603017 DOI: 10.1016/j.jmb.2013.04.014] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2013] [Revised: 04/09/2013] [Accepted: 04/15/2013] [Indexed: 01/12/2023]
Abstract
The "Replicon Theory" of Jacob, Brenner, and Cuzin has reliably served as the paradigm for regulating the sites where individual replicons initiate replication. Concurrent with the replicon model was Taylor's demonstration that plant and animal chromosomes replicate segmentally in a defined temporal sequence, via cytologically defined units too large to be accounted for by a single replicon. Instead, there seemed to be a program to choreograph when chromosome units replicate during S phase, executed by initiation at clusters of individual replicons within each segment. Here, we summarize recent molecular evidence for the existence of such units, now known as "replication domains", and discuss how the organization of large chromosomes into structural units has added additional layers of regulation to the original replicon model.
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Affiliation(s)
- Benjamin D Pope
- Department of Biological Science, Florida State University, 319 Stadium Drive, Tallahassee, FL 32306-4295, USA
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