1
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D'Alfonso A, Micheli G, Camilloni G. rDNA transcription, replication and stability in Saccharomyces cerevisiae. Semin Cell Dev Biol 2024; 159-160:1-9. [PMID: 38244478 DOI: 10.1016/j.semcdb.2024.01.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2023] [Revised: 12/20/2023] [Accepted: 01/10/2024] [Indexed: 01/22/2024]
Abstract
The ribosomal DNA locus (rDNA) is central for the functioning of cells because it encodes ribosomal RNAs, key components of ribosomes, and also because of its links to fundamental metabolic processes, with significant impact on genome integrity and aging. The repetitive nature of the rDNA gene units forces the locus to maintain sequence homogeneity through recombination processes that are closely related to genomic stability. The co-presence of basic DNA transactions, such as replication, transcription by major RNA polymerases, and recombination, in a defined and restricted area of the genome is of particular relevance as it affects the stability of the rDNA locus by both direct and indirect mechanisms. This condition is well exemplified by the rDNA of Saccharomyces cerevisiae. In this review we summarize essential knowledge on how the complexity and overlap of different processes contribute to the control of rDNA and genomic stability in this model organism.
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Affiliation(s)
- Anna D'Alfonso
- Dipartimento di Biologia e Biotecnologie C. Darwin, Università degli studi di Roma, Sapienza, Rome, Italy
| | - Gioacchino Micheli
- Istituto di Biologia e Patologia Molecolari, Consiglio Nazionale delle Ricerche, Rome, Italy
| | - Giorgio Camilloni
- Dipartimento di Biologia e Biotecnologie C. Darwin, Università degli studi di Roma, Sapienza, Rome, Italy.
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2
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Murai T, Yanagi S, Hori Y, Kobayashi T. Replication fork blocking deficiency leads to a reduction of rDNA copy number in budding yeast. iScience 2024; 27:109120. [PMID: 38384843 PMCID: PMC10879690 DOI: 10.1016/j.isci.2024.109120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2023] [Revised: 11/27/2023] [Accepted: 01/31/2024] [Indexed: 02/23/2024] Open
Abstract
The ribosomal RNA genes are encoded as hundreds of tandem repeats, known as the rDNA, in eukaryotes. Maintaining these copies seems to be necessary, but copy number changes in an active manner have been reported in only frogs, flies, Neurospora, and yeast. In the best-studied system, yeast, a protein (Fob1) binds to the rDNA and unidirectionally blocks the replication fork. This block stimulates rDNA double-strand breaks (DSBs) leading to recombination and copy number change. To date, copy number maintenance and concerted evolution mediated by rDNA repeat turnover were the proposed benefits of Fob1-dependent replication fork arrest. In this study, we tested whether Fob1 provides these benefits and found that rDNA copy number decreases when FOB1 is deleted, suggesting that Fob1 is important for recovery from low copy number. We suppose that replication fork stalling at rDNA is necessary for recovering from rDNA copy number loss in other species as well.
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Affiliation(s)
- Taichi Murai
- Laboratory of Genome Regeneration, Institute for Quantitative Biosciences (IQB), The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan
- Department of Biological Sciences, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Shuichi Yanagi
- Laboratory of Genome Regeneration, Institute for Quantitative Biosciences (IQB), The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan
| | - Yutaro Hori
- Laboratory of Genome Regeneration, Institute for Quantitative Biosciences (IQB), The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan
| | - Takehiko Kobayashi
- Laboratory of Genome Regeneration, Institute for Quantitative Biosciences (IQB), The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan
- Department of Biological Sciences, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
- Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan
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3
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Garcia S, Kovarik A, Maiwald S, Mann L, Schmidt N, Pascual-Díaz JP, Vitales D, Weber B, Heitkam T. The Dynamic Interplay Between Ribosomal DNA and Transposable Elements: A Perspective From Genomics and Cytogenetics. Mol Biol Evol 2024; 41:msae025. [PMID: 38306580 PMCID: PMC10946416 DOI: 10.1093/molbev/msae025] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Revised: 12/06/2023] [Accepted: 01/29/2024] [Indexed: 02/04/2024] Open
Abstract
Although both are salient features of genomes, at first glance ribosomal DNAs and transposable elements are genetic elements with not much in common: whereas ribosomal DNAs are mainly viewed as housekeeping genes that uphold all prime genome functions, transposable elements are generally portrayed as selfish and disruptive. These opposing characteristics are also mirrored in other attributes: organization in tandem (ribosomal DNAs) versus organization in a dispersed manner (transposable elements); evolution in a concerted manner (ribosomal DNAs) versus evolution by diversification (transposable elements); and activity that prolongs genomic stability (ribosomal DNAs) versus activity that shortens it (transposable elements). Re-visiting relevant instances in which ribosomal DNA-transposable element interactions have been reported, we note that both repeat types share at least four structural and functional hallmarks: (1) they are repetitive DNAs that shape genomes in evolutionary timescales, (2) they exchange structural motifs and can enter co-evolution processes, (3) they are tightly controlled genomic stress sensors playing key roles in senescence/aging, and (4) they share common epigenetic marks such as DNA methylation and histone modification. Here, we give an overview of the structural, functional, and evolutionary characteristics of both ribosomal DNAs and transposable elements, discuss their roles and interactions, and highlight trends and future directions as we move forward in understanding ribosomal DNA-transposable element associations.
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Affiliation(s)
- Sònia Garcia
- Institut Botànic de Barcelona (IBB), CSIC-CMCNB, 08038 Barcelona, Catalonia, Spain
| | - Ales Kovarik
- Institute of Biophysics, Academy of Sciences of the Czech Republic, 61265 Brno, Czech Republic
| | - Sophie Maiwald
- Faculty of Biology, Technische Universität Dresden, D-01069 Dresden, Germany
| | - Ludwig Mann
- Faculty of Biology, Technische Universität Dresden, D-01069 Dresden, Germany
| | - Nicola Schmidt
- Faculty of Biology, Technische Universität Dresden, D-01069 Dresden, Germany
| | | | - Daniel Vitales
- Institut Botànic de Barcelona (IBB), CSIC-CMCNB, 08038 Barcelona, Catalonia, Spain
- Laboratori de Botànica–Unitat Associada CSIC, Facultat de Farmàcia i Ciències de l’Alimentació, Universitat de Barcelona, 08028 Barcelona, Catalonia, Spain
| | - Beatrice Weber
- Faculty of Biology, Technische Universität Dresden, D-01069 Dresden, Germany
| | - Tony Heitkam
- Faculty of Biology, Technische Universität Dresden, D-01069 Dresden, Germany
- Institute of Biology, NAWI Graz, Karl-Franzens-Universität, A-8010 Graz, Austria
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4
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Li J, Stenberg S, Yue JX, Mikhalev E, Thompson D, Warringer J, Liti G. Genome instability footprint under rapamycin and hydroxyurea treatments. PLoS Genet 2023; 19:e1011012. [PMID: 37931001 PMCID: PMC10653606 DOI: 10.1371/journal.pgen.1011012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2023] [Revised: 11/16/2023] [Accepted: 10/10/2023] [Indexed: 11/08/2023] Open
Abstract
The mutational processes dictating the accumulation of mutations in genomes are shaped by genetic background, environment and their interactions. Accurate quantification of mutation rates and spectra under drugs has important implications in disease treatment. Here, we used whole-genome sequencing and time-resolved growth phenotyping of yeast mutation accumulation lines to give a detailed view of the mutagenic effects of rapamycin and hydroxyurea on the genome and cell growth. Mutation rates depended on the genetic backgrounds but were only marginally affected by rapamycin. As a remarkable exception, rapamycin treatment was associated with frequent chromosome XII amplifications, which compensated for rapamycin induced rDNA repeat contraction on this chromosome and served to maintain rDNA content homeostasis and fitness. In hydroxyurea, a wide range of mutation rates were elevated regardless of the genetic backgrounds, with a particularly high occurrence of aneuploidy that associated with dramatic fitness loss. Hydroxyurea also induced a high T-to-G and low C-to-A transversion rate that reversed the common G/C-to-A/T bias in yeast and gave rise to a broad range of structural variants, including mtDNA deletions. The hydroxyurea mutation footprint was consistent with the activation of error-prone DNA polymerase activities and non-homologues end joining repair pathways. Taken together, our study provides an in-depth view of mutation rates and signatures in rapamycin and hydroxyurea and their impact on cell fitness, which brings insights for assessing their chronic effects on genome integrity.
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Affiliation(s)
- Jing Li
- State Key Laboratory of Oncology in South China, Guangdong Provincial Clinical Research Center for Cancer, Sun Yat-sen University Cancer Center, Guangzhou, P. R. China
- Université Côte d’Azur, CNRS, INSERM, IRCAN, Nice, France
| | - Simon Stenberg
- Department of Chemistry and Molecular Biology, University of Gothenburg, Gothenburg, Sweden
| | - Jia-Xing Yue
- State Key Laboratory of Oncology in South China, Guangdong Provincial Clinical Research Center for Cancer, Sun Yat-sen University Cancer Center, Guangzhou, P. R. China
- Université Côte d’Azur, CNRS, INSERM, IRCAN, Nice, France
| | | | - Dawn Thompson
- Ginkgo Bioworks, Boston, Massachusetts, United States of America
| | - Jonas Warringer
- Department of Chemistry and Molecular Biology, University of Gothenburg, Gothenburg, Sweden
| | - Gianni Liti
- Université Côte d’Azur, CNRS, INSERM, IRCAN, Nice, France
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5
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Sharp NP, Smith DR, Driscoll G, Sun K, Vickerman CM, Martin SCT. Contribution of Spontaneous Mutations to Quantitative and Molecular Variation at the Highly Repetitive rDNA Locus in Yeast. Genome Biol Evol 2023; 15:evad179. [PMID: 37847861 PMCID: PMC10581546 DOI: 10.1093/gbe/evad179] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/26/2023] [Indexed: 10/19/2023] Open
Abstract
The ribosomal DNA array in Saccharomyces cerevisiae consists of many tandem repeats whose copy number is believed to be functionally important but highly labile. Regulatory mechanisms have evolved to maintain copy number by directed mutation, but how spontaneous variation at this locus is generated and selected has not been well characterized. We applied a mutation accumulation approach to quantify the impacts of mutation and selection on this unique genomic feature across hundreds of mutant strains. We find that mutational variance for this trait is relatively high, and that unselected mutations elsewhere in the genome can disrupt copy number maintenance. In consequence, copy number generally declines gradually, consistent with a previously proposed model of rDNA maintenance where a downward mutational bias is normally compensated by mechanisms that increase copy number when it is low. This pattern holds across ploidy levels and strains in the standard lab environment but differs under some stressful conditions. We identify several alleles, gene categories, and genomic features that likely affect copy number, including aneuploidy for chromosome XII. Copy number change is associated with reduced growth in diploids, consistent with stabilizing selection. Levels of standing variation in copy number are well predicted by a balance between mutation and stabilizing selection, suggesting this trait is not subject to strong diversifying selection in the wild. The rate and spectrum of point mutations within the rDNA locus itself are distinct from the rest of the genome and predictive of polymorphism locations. Our findings help differentiate the roles of mutation and selection and indicate that spontaneous mutation patterns shape several aspects of ribosomal DNA evolution.
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Affiliation(s)
- Nathaniel P Sharp
- Department of Genetics, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Denise R Smith
- Department of Genetics, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Gregory Driscoll
- Department of Genetics, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Kexin Sun
- Present address: Department of Biostatistics, University of North Carolina, Chapel Hill, North Carolina, USA
| | | | - Sterling C T Martin
- Present address: Department of Biology, Washington University, St. Louis, Missouri, USA
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6
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Fu W, MacGregor DR, Comont D, Saski CA. Sequence Characterization of Extra-Chromosomal Circular DNA Content in Multiple Blackgrass ( Alopecurus myosuroides) Populations. Genes (Basel) 2023; 14:1905. [PMID: 37895254 PMCID: PMC10606437 DOI: 10.3390/genes14101905] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2023] [Revised: 09/27/2023] [Accepted: 09/28/2023] [Indexed: 10/29/2023] Open
Abstract
Alopecurus myosuroides (blackgrass) is a problematic weed of Western European winter wheat, and its success is largely due to widespread multiple-herbicide resistance. Previous analysis of F2 seed families derived from two distinct blackgrass populations exhibiting equivalent non-target site resistance (NTSR) phenotypes shows resistance is polygenic and evolves from standing genetic variation. Using a CIDER-seq pipeline, we show that herbicide-resistant (HR) and herbicide-sensitive (HS) F3 plants from these F2 seed families as well as the parent populations they were derived from carry extra-chromosomal circular DNA (eccDNA). We identify the similarities and differences in the coding structures within and between resistant and sensitive populations. Although the numbers and size of detected eccDNAs varied between the populations, comparisons between the HR and HS blackgrass populations identified shared and unique coding content, predicted genes, and functional protein domains. These include genes related to herbicide detoxification such as Cytochrome P450s, ATP-binding cassette transporters, and glutathione transferases including AmGSTF1. eccDNA content was mapped to the A. myosuroides reference genome, revealing genomic regions at the distal end of chromosome 5 and the near center of chromosomes 1 and 7 as regions with a high number of mapped eccDNA gene density. Mapping to 15 known herbicide-resistant QTL regions showed that the eccDNA coding sequences matched twelve, with four QTL matching HS coding sequences; only one region contained HR coding sequences. These findings establish that, like other pernicious weeds, blackgrass has eccDNAs that contain homologs of chromosomal genes, and these may contribute genetic heterogeneity and evolutionary innovation to rapidly adapt to abiotic stresses, including herbicide treatment.
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Affiliation(s)
- Wangfang Fu
- Department of Plant and Environmental Sciences, Clemson University, Clemson, SC 29634, USA;
| | - Dana R. MacGregor
- Rothamsted Research, Protecting Crops and the Environment, Harpenden, Hertfordshire AL5 2JQ, UK; (D.R.M.); (D.C.)
| | - David Comont
- Rothamsted Research, Protecting Crops and the Environment, Harpenden, Hertfordshire AL5 2JQ, UK; (D.R.M.); (D.C.)
| | - Christopher A. Saski
- Department of Plant and Environmental Sciences, Clemson University, Clemson, SC 29634, USA;
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7
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Sasaki M, Kobayashi T. Regulatory processes that maintain or alter ribosomal DNA stability during the repair of programmed DNA double-strand breaks. Genes Genet Syst 2023; 98:103-119. [PMID: 35922917 DOI: 10.1266/ggs.22-00046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Organisms have evolved elaborate mechanisms that maintain genome stability. Deficiencies in these mechanisms result in changes to the nucleotide sequence as well as copy number and structural variations in the genome. Genome instability has been implicated in numerous human diseases. However, genomic alterations can also be beneficial as they are an essential part of the evolutionary process. Organisms sometimes program genomic changes that drive genetic and phenotypic diversity. Therefore, genome alterations can have both positive and negative impacts on cellular growth and functions, which underscores the need to control the processes that restrict or induce such changes to the genome. The ribosomal RNA gene (rDNA) is highly abundant in eukaryotic genomes, forming a cluster where numerous rDNA copies are tandemly arrayed. Budding yeast can alter the stability of its rDNA cluster by changing the rDNA copy number within the cluster or by producing extrachromosomal rDNA circles. Here, we review the mechanisms that regulate the stability of the budding yeast rDNA cluster during repair of DNA double-strand breaks that are formed in response to programmed DNA replication fork arrest.
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Affiliation(s)
- Mariko Sasaki
- Laboratory of Genome Regeneration, Institute for Quantitative Biosciences (IQB), The University of Tokyo
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo
| | - Takehiko Kobayashi
- Laboratory of Genome Regeneration, Institute for Quantitative Biosciences (IQB), The University of Tokyo
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo
- Collaborative Research Institute for Innovative Microbiology, The University of Tokyo
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8
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López-Gil L, Pascual-Ahuir A, Proft M. Genomic Instability and Epigenetic Changes during Aging. Int J Mol Sci 2023; 24:14279. [PMID: 37762580 PMCID: PMC10531692 DOI: 10.3390/ijms241814279] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Revised: 09/15/2023] [Accepted: 09/18/2023] [Indexed: 09/29/2023] Open
Abstract
Aging is considered the deterioration of physiological functions along with an increased mortality rate. This scientific review focuses on the central importance of genomic instability during the aging process, encompassing a range of cellular and molecular changes that occur with advancing age. In particular, this revision addresses the genetic and epigenetic alterations that contribute to genomic instability, such as telomere shortening, DNA damage accumulation, and decreased DNA repair capacity. Furthermore, the review explores the epigenetic changes that occur with aging, including modifications to histones, DNA methylation patterns, and the role of non-coding RNAs. Finally, the review discusses the organization of chromatin and its contribution to genomic instability, including heterochromatin loss, chromatin remodeling, and changes in nucleosome and histone abundance. In conclusion, this review highlights the fundamental role that genomic instability plays in the aging process and underscores the need for continued research into these complex biological mechanisms.
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Affiliation(s)
- Lucía López-Gil
- Department of Biotechnology, Instituto de Biología Molecular y Celular de Plantas, Universitat Politècnica de València, Ingeniero Fausto Elio s/n, 46022 Valencia, Spain;
- Department of Molecular and Cellular Pathology and Therapy, Instituto de Biomedicina de Valencia IBV-CSIC, Consejo Superior de Investigaciones Científicas CSIC, Jaime Roig 11, 46010 Valencia, Spain
| | - Amparo Pascual-Ahuir
- Department of Biotechnology, Instituto de Biología Molecular y Celular de Plantas, Universitat Politècnica de València, Ingeniero Fausto Elio s/n, 46022 Valencia, Spain;
| | - Markus Proft
- Department of Molecular and Cellular Pathology and Therapy, Instituto de Biomedicina de Valencia IBV-CSIC, Consejo Superior de Investigaciones Científicas CSIC, Jaime Roig 11, 46010 Valencia, Spain
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9
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Zylstra A, Hadj-Moussa H, Horkai D, Whale AJ, Piguet B, Houseley J. Senescence in yeast is associated with amplified linear fragments of chromosome XII rather than ribosomal DNA circle accumulation. PLoS Biol 2023; 21:e3002250. [PMID: 37643194 PMCID: PMC10464983 DOI: 10.1371/journal.pbio.3002250] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Accepted: 07/12/2023] [Indexed: 08/31/2023] Open
Abstract
The massive accumulation of extrachromosomal ribosomal DNA circles (ERCs) in yeast mother cells has been long cited as the primary driver of replicative ageing. ERCs arise through ribosomal DNA (rDNA) recombination, and a wealth of genetic data connects rDNA instability events giving rise to ERCs with shortened life span and other ageing pathologies. However, we understand little about the molecular effects of ERC accumulation. Here, we studied ageing in the presence and absence of ERCs, and unexpectedly found no evidence of gene expression differences that might indicate stress responses or metabolic feedback caused by ERCs. Neither did we observe any global change in the widespread disruption of gene expression that accompanies yeast ageing, altogether suggesting that ERCs are largely inert. Much of the differential gene expression that accompanies ageing in yeast was actually associated with markers of the senescence entry point (SEP), showing that senescence, rather than age, underlies these changes. Cells passed the SEP irrespective of ERCs, but we found the SEP to be associated with copy number amplification of a region of chromosome XII between the rDNA and the telomere (ChrXIIr) forming linear fragments up to approximately 1.8 Mb size, which arise in aged cells due to rDNA instability but through a different mechanism to ERCs. Therefore, although rDNA copy number increases dramatically with age due to ERC accumulation, our findings implicate ChrXIIr, rather than ERCs, as the primary driver of senescence during budding yeast ageing.
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Affiliation(s)
- Andre Zylstra
- Epigenetics Programme, Babraham Institute, Cambridge, United Kingdom
| | | | - Dorottya Horkai
- Epigenetics Programme, Babraham Institute, Cambridge, United Kingdom
| | - Alex J. Whale
- Epigenetics Programme, Babraham Institute, Cambridge, United Kingdom
| | - Baptiste Piguet
- Epigenetics Programme, Babraham Institute, Cambridge, United Kingdom
| | - Jonathan Houseley
- Epigenetics Programme, Babraham Institute, Cambridge, United Kingdom
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10
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Yokoyama M, Sasaki M, Kobayashi T. Spt4 promotes cellular senescence by activating non-coding RNA transcription in ribosomal RNA gene clusters. Cell Rep 2023; 42:111944. [PMID: 36640349 DOI: 10.1016/j.celrep.2022.111944] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Revised: 07/06/2022] [Accepted: 12/19/2022] [Indexed: 01/11/2023] Open
Abstract
Genome instability can drive aging in many organisms. The ribosomal RNA gene (rDNA) cluster is one of the most unstable regions in the genome and the stability of this region impacts replicative lifespan in budding yeast. To understand the underlying mechanism, we search for yeast mutants with stabler rDNA and longer lifespans than wild-type cells. We show that absence of a transcription elongation factor, Spt4, results in increased rDNA stability, reduced levels of non-coding RNA transcripts from the regulatory E-pro promoter in the rDNA, and extended replicative lifespan in a SIR2-dependent manner. Spt4-dependent lifespan restriction is abolished in the absence of non-coding RNA transcription at the E-pro locus. The amount of Spt4 increases and its function becomes more important as cells age. These findings suggest that Spt4 is a promising aging factor that accelerates cellular senescence through rDNA instability driven by non-coding RNA transcription.
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Affiliation(s)
- Masaaki Yokoyama
- Laboratory of Genome Regeneration, Institute for Quantitative Biosciences (IQB), The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan; Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Mariko Sasaki
- Laboratory of Genome Regeneration, Institute for Quantitative Biosciences (IQB), The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan; Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
| | - Takehiko Kobayashi
- Laboratory of Genome Regeneration, Institute for Quantitative Biosciences (IQB), The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan; Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan; Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan.
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11
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Guo J, Zhang Z, Li Q, Chang X, Liu X. TeCD: The eccDNA Collection Database for extrachromosomal circular DNA. BMC Genomics 2023; 24:47. [PMID: 36707765 PMCID: PMC9881285 DOI: 10.1186/s12864-023-09135-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Accepted: 01/13/2023] [Indexed: 01/28/2023] Open
Abstract
BACKGROUND Extrachromosomal circular DNA (eccDNA) is a kind of DNA that widely exists in eukaryotic cells. Studies in recent years have shown that eccDNA is often enriched during tumors and aging, and participates in the development of cell physiological activities in a special way, so people have paid more and more attention to the eccDNA, and it has also become a critical new topic in modern biological research. DESCRIPTION We built a database to collect eccDNA, including animals, plants and fungi, and provide researchers with an eccDNA retrieval platform. The collected eccDNAs were processed in a uniform format and classified according to the species to which it belongs and the chromosome of the source. Each eccDNA record contained sequence length, start and end sites on the corresponding chromosome, order of the bases, genomic elements such as genes and transposons, and other information in the respective sequencing experiment. All the data were stored into the TeCD (The eccDNA Collection Database) and the BLAST (Basic Local Alignment Search Tool) sequence alignment function was also added into the database for analyzing the potential eccDNA sequences. CONCLUSION We built TeCD, a platform for users to search and obtain eccDNA data, and analyzed the possible potential functions of eccDNA. These findings may provide a basis and direction for researchers to further explore the biological significance of eccDNA in the future.
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Affiliation(s)
- Jing Guo
- grid.410726.60000 0004 1797 8419Key Laboratory of Systems Biology, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou, 310013 China ,grid.410726.60000 0004 1797 8419Key Laboratory of Systems Health Science of Zhejiang Province, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou, 310013 China ,grid.464226.00000 0004 1760 7263Institute of Statistics and Applied Mathematics, Anhui University of Finance & Economics, Bengbu, 233030 China ,grid.27255.370000 0004 1761 1174School of Mathematics and Statistics, Shandong University, Weihai, 264209 Shandong China
| | - Ze Zhang
- grid.410726.60000 0004 1797 8419Key Laboratory of Systems Biology, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou, 310013 China ,grid.410726.60000 0004 1797 8419Key Laboratory of Systems Health Science of Zhejiang Province, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou, 310013 China ,grid.410726.60000 0004 1797 8419School of Life Science, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou, 310013 China
| | - Qingcui Li
- grid.410726.60000 0004 1797 8419School of Life Science, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou, 310013 China
| | - Xiao Chang
- grid.464226.00000 0004 1760 7263Institute of Statistics and Applied Mathematics, Anhui University of Finance & Economics, Bengbu, 233030 China
| | - Xiaoping Liu
- grid.410726.60000 0004 1797 8419Key Laboratory of Systems Biology, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou, 310013 China ,grid.410726.60000 0004 1797 8419Key Laboratory of Systems Health Science of Zhejiang Province, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou, 310013 China ,grid.27255.370000 0004 1761 1174School of Mathematics and Statistics, Shandong University, Weihai, 264209 Shandong China
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12
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Mansisidor AR, Risca VI. Chromatin accessibility: methods, mechanisms, and biological insights. Nucleus 2022; 13:236-276. [PMID: 36404679 PMCID: PMC9683059 DOI: 10.1080/19491034.2022.2143106] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Revised: 10/23/2022] [Accepted: 10/30/2022] [Indexed: 11/22/2022] Open
Abstract
Access to DNA is a prerequisite to the execution of essential cellular processes that include transcription, replication, chromosomal segregation, and DNA repair. How the proteins that regulate these processes function in the context of chromatin and its dynamic architectures is an intensive field of study. Over the past decade, genome-wide assays and new imaging approaches have enabled a greater understanding of how access to the genome is regulated by nucleosomes and associated proteins. Additional mechanisms that may control DNA accessibility in vivo include chromatin compaction and phase separation - processes that are beginning to be understood. Here, we review the ongoing development of accessibility measurements, we summarize the different molecular and structural mechanisms that shape the accessibility landscape, and we detail the many important biological functions that are linked to chromatin accessibility.
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Affiliation(s)
- Andrés R. Mansisidor
- Laboratory of Genome Architecture and Dynamics, The Rockefeller University, New York, NY
| | - Viviana I. Risca
- Laboratory of Genome Architecture and Dynamics, The Rockefeller University, New York, NY
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13
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Extrachromosomal circular DNA: biogenesis, structure, functions and diseases. Signal Transduct Target Ther 2022; 7:342. [PMID: 36184613 PMCID: PMC9527254 DOI: 10.1038/s41392-022-01176-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Revised: 08/14/2022] [Accepted: 09/01/2022] [Indexed: 11/08/2022] Open
Abstract
Extrachromosomal circular DNA (eccDNA), ranging in size from tens to millions of base pairs, is independent of conventional chromosomes. Recently, eccDNAs have been considered an unanticipated major source of somatic rearrangements, contributing to genomic remodeling through chimeric circularization and reintegration of circular DNA into the linear genome. In addition, the origin of eccDNA is considered to be associated with essential chromatin-related events, including the formation of super-enhancers and DNA repair machineries. Moreover, our understanding of the properties and functions of eccDNA has continuously and greatly expanded. Emerging investigations demonstrate that eccDNAs serve as multifunctional molecules in various organisms during diversified biological processes, such as epigenetic remodeling, telomere trimming, and the regulation of canonical signaling pathways. Importantly, its special distribution potentiates eccDNA as a measurable biomarker in many diseases, especially cancers. The loss of eccDNA homeostasis facilitates tumor initiation, malignant progression, and heterogeneous evolution in many cancers. An in-depth understanding of eccDNA provides novel insights for precision cancer treatment. In this review, we summarized the discovery history of eccDNA, discussed the biogenesis, characteristics, and functions of eccDNA. Moreover, we emphasized the role of eccDNA during tumor pathogenesis and malignant evolution. Therapeutically, we summarized potential clinical applications that target aberrant eccDNA in multiple diseases.
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14
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Peng H, Mirouze M, Bucher E. Extrachromosomal circular DNA: A neglected nucleic acid molecule in plants. CURRENT OPINION IN PLANT BIOLOGY 2022; 69:102263. [PMID: 35872391 DOI: 10.1016/j.pbi.2022.102263] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Revised: 06/15/2022] [Accepted: 06/19/2022] [Indexed: 06/15/2023]
Abstract
Throughout the years, most plant genomic studies were focused on nuclear chromosomes. Extrachromosomal circular DNA (eccDNA) has largely been neglected for decades since its discovery in 1965. While initial research showed that eccDNAs can originate from highly repetitive sequences, recent findings show that many regions of the genome can contribute to the eccDNA pool. Currently, the biological functions of eccDNAs, if any, are a mystery but recent studies have indicated that they can be regulated by different genomic loci and contribute to stress response and adaptation. In this review, we outline current relevant technological developments facilitating eccDNA identification and the latest discoveries about eccDNAs in plants. Finally, we explore the probable functions and future research directions that could be undertaken with respect to different eccDNA sources.
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Affiliation(s)
- Haoran Peng
- Crop Genome Dynamics Group, Agroscope Changins, 1260, Nyon, Switzerland; Department of Botany and Plant Biology, Section of Biology, Faculty of Science, University of Geneva, 1211, Geneva, Switzerland
| | - Marie Mirouze
- Institut de Recherche pour le Développement (IRD), EMR269 MANGO, Université de Perpignan, 66860 Perpignan, France; Laboratory of Plant Genome and Development, Université de Perpignan, 66860, Perpignan, France.
| | - Etienne Bucher
- Crop Genome Dynamics Group, Agroscope Changins, 1260, Nyon, Switzerland.
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15
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Li R, Wang Y, Li J, Zhou X. Extrachromosomal circular DNA (eccDNA): an emerging star in cancer. Biomark Res 2022; 10:53. [PMID: 35883211 PMCID: PMC9327165 DOI: 10.1186/s40364-022-00399-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2022] [Accepted: 07/13/2022] [Indexed: 02/08/2023] Open
Abstract
Extrachromosomal circular DNA (eccDNA) is defined as a type of circular DNA that exists widely in nature and is independent of chromosomes. EccDNA has attracted the attention of researchers due to its broad, random distribution, complex biogenesis and tumor-relevant functions. EccDNA can carry complete gene information, especially the oncogenic driver genes that are often carried in tumors, with increased copy number and high transcriptional activity. The high overexpression of oncogenes by eccDNA leads to malignant growth of tumors. Regardless, the exact generation and functional mechanisms of eccDNA in disease progression are not yet clear. There is, however, an emerging body of evidence characterizing that eccDNA can be generated from multiple pathways, including DNA damage repair pathways, breakage-fusion-bridge (BFB) mechanisms, chromothripsis and cell apoptosis, and participates in the regulation of tumor progression with multiplex functions. This up-to-date review summarizes and discusses the origins, biogenesis and functions of eccDNA, including its contribution to the formation of oncogene instability and mutations, the heterogeneity and cellular senescence of tumor cells, and the proinflammatory response of tumors. We highlight the possible cancer-related applications of eccDNA, such as its potential use in the diagnosis, targeted therapy and prognostic assessment of cancer.
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Affiliation(s)
- Ruomeng Li
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University and Collaborative Innovation Center for Biotherapy, Chengdu, 610041, China.,State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, Chinese Academy of Medical Sciences Research Unit of Oral Carcinogenesis and Management, West China Hospital of Stomatology, Sichuan University, Chengdu, Sichuan, 610041, PR China
| | - Ying Wang
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, Chinese Academy of Medical Sciences Research Unit of Oral Carcinogenesis and Management, West China Hospital of Stomatology, Sichuan University, Chengdu, Sichuan, 610041, PR China
| | - Jing Li
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, Chinese Academy of Medical Sciences Research Unit of Oral Carcinogenesis and Management, West China Hospital of Stomatology, Sichuan University, Chengdu, Sichuan, 610041, PR China.
| | - Xikun Zhou
- State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University and Collaborative Innovation Center for Biotherapy, Chengdu, 610041, China.
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16
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Sharma D, Denmat SHL, Matzke NJ, Hannan K, Hannan RD, O'Sullivan JM, Ganley ARD. A new method for determining ribosomal DNA copy number shows differences between Saccharomyces cerevisiae populations. Genomics 2022; 114:110430. [PMID: 35830947 DOI: 10.1016/j.ygeno.2022.110430] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Revised: 05/23/2022] [Accepted: 07/04/2022] [Indexed: 11/26/2022]
Abstract
Ribosomal DNA genes (rDNA) encode the major ribosomal RNAs and in eukaryotes typically form tandem repeat arrays. Species have characteristic rDNA copy numbers, but there is substantial intra-species variation in copy number that results from frequent rDNA recombination. Copy number differences can have phenotypic consequences, however difficulties in quantifying copy number mean we lack a comprehensive understanding of how copy number evolves and the consequences. Here we present a genomic sequence read approach to estimate rDNA copy number based on modal coverage to help overcome limitations with existing mean coverage-based approaches. We validated our method using Saccharomyces cerevisiae strains with known rDNA copy numbers. Application of our pipeline to a global sample of S. cerevisiae isolates showed that different populations have different rDNA copy numbers. Our results demonstrate the utility of the modal coverage method, and highlight the high level of rDNA copy number variation within and between populations.
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Affiliation(s)
- Diksha Sharma
- School of Biological Sciences, University of Auckland, Auckland, New Zealand
| | - Sylvie Hermann-Le Denmat
- School of Biological Sciences, University of Auckland, Auckland, New Zealand; Ecole Normale Supérieure, PSL Research University, F-75005 Paris, France
| | - Nicholas J Matzke
- School of Biological Sciences, University of Auckland, Auckland, New Zealand
| | - Katherine Hannan
- ACRF Department of Cancer Biology and Therapeutics, The John Curtin School of Medical Research, ACT 2601, Australia; Department of Biochemistry and Molecular Biology, University of Melbourne, Parkville, Victoria 3010, Australia
| | - Ross D Hannan
- ACRF Department of Cancer Biology and Therapeutics, The John Curtin School of Medical Research, ACT 2601, Australia; Department of Biochemistry and Molecular Biology, University of Melbourne, Parkville, Victoria 3010, Australia; Division of Research, Peter MacCallum Cancer Centre, Melbourne, Victoria 3000, Australia; Sir Peter MacCallum Department of Oncology, University of Melbourne, Parkville, Victoria 3010, Australia; Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria 3168, Australia
| | - Justin M O'Sullivan
- Liggins Institute, University of Auckland, Auckland, New Zealand; Maurice Wilkins Center, University of Auckland, New Zealand; MRC Lifecourse Unit, University of Southampton, United Kingdom; Brain Research New Zealand, The University of Auckland, Auckland, New Zealand
| | - Austen R D Ganley
- School of Biological Sciences, University of Auckland, Auckland, New Zealand.
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17
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The long and short of rDNA and yeast replicative aging. Proc Natl Acad Sci U S A 2022; 119:e2205124119. [PMID: 35658078 DOI: 10.1073/pnas.2205124119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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18
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Xiong W, Li C, Kong G, Wan B, Wang S, Fan J. Glioblastoma: two immune subtypes under the surface of the cold tumor. Aging (Albany NY) 2022; 14:4357-4375. [PMID: 35609054 PMCID: PMC9186767 DOI: 10.18632/aging.204067] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Accepted: 04/22/2022] [Indexed: 12/02/2022]
Abstract
Glioblastoma is classified as an immunocompromised tumor. The immune pattern beneath the cold tumor surface, however, has yet to be confirmed. Understanding the immune pattern of glioblastoma will aid in the development of effective treatment strategies. We performed weighted gene co-expression network analysis on all immune-related genes in TCGA-GBM transcriptional data and screened 35 prognosis-related immune genes. Unsupervised consistent clustering of these genes was used to analyze the immunological pattern of GBM. A glioblastoma immune prognostic score was developed by using 13 genes discovered by cox regression methods and verified with the GEO dataset to assess the immune profile, prognosis, and immunotherapy effects in individual patients. Glioblastoma has two immune modalities, immune tolerance and immunodeficiency, with distinct immune microenvironments, tumor-associated macrophages being one of the most promising new therapeutic targets. GIPS is a promising biomarker for assessing immune evasion mechanisms, immunotherapy responses, and prognosis in patients.
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Affiliation(s)
- Wu Xiong
- Department of Orthopedics, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, China.,Nanjing Medical University, Nanjing, Jiangsu, China
| | - Cong Li
- Department of Orthopedics, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, China.,Nanjing Medical University, Nanjing, Jiangsu, China
| | - Guang Kong
- Nanjing Medical University, Nanjing, Jiangsu, China
| | - Bowen Wan
- Department of Orthopedics, Clinical Medical College of Yangzhou University, Subei People's Hospital of Jiangsu, Yangzhou, Jiangsu, China
| | - Siming Wang
- Department of Orthopedics, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, China.,Nanjing Medical University, Nanjing, Jiangsu, China
| | - Jin Fan
- Department of Orthopedics, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, China.,Nanjing Medical University, Nanjing, Jiangsu, China
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19
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Abstract
Genes encoding ribosomal RNA (rDNA) are organized into a repetitive array in eukaryotic genomes. The copy number of these genes often varies and is responsive to genetics and environment. Here, we show that variation in copy number at the rDNA locus is capable of altering replicative lifespan in yeast. These results indicate that considering rDNA copy number, and conditions that could potentially change this dynamic chromosome locus, is critical for evaluating lifespan. We propose that this rDNA locus represents the kind of repeated element in eukaryotic genomes that escapes easy detection, yet has phenotypic consequences, in this case lifespan. The complex processes and interactions that regulate aging and determine lifespan are not fully defined for any organism. Here, taking advantage of recent technological advances in studying aging in budding yeast, we discovered a previously unappreciated relationship between the number of copies of the ribosomal RNA gene present in its chromosomal array and replicative lifespan (RLS). Specifically, the chromosomal ribosomal DNA (rDNA) copy number (rDNA CN) positively correlated with RLS and this interaction explained over 70% of variability in RLS among a series of wild-type strains. In strains with low rDNA CN, SIR2 expression was attenuated and extrachromosomal rDNA circle (ERC) accumulation was increased, leading to shorter lifespan. Suppressing ERC formation by deletion of FOB1 eliminated the relationship between rDNA CN and RLS. These data suggest that previously identified rDNA CN regulatory mechanisms limit lifespan. Importantly, the RLSs of reported lifespan-enhancing mutations were significantly impacted by rDNA CN, suggesting that changes in rDNA CN might explain the magnitude of some of those reported effects. We propose that because rDNA CN is modulated by environmental, genetic, and stochastic factors, considering rDNA CN is a prerequisite for accurate interpretation of lifespan data.
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20
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Ding Q, Li R, Ren X, Chan LY, Ho VWS, Xie D, Ye P, Zhao Z. Genomic architecture of 5S rDNA cluster and its variations within and between species. BMC Genomics 2022; 23:238. [PMID: 35346033 PMCID: PMC8961926 DOI: 10.1186/s12864-022-08476-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Accepted: 03/16/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Ribosomal DNAs (rDNAs) are arranged in purely tandem repeats, preventing them from being reliably assembled onto chromosomes during generation of genome assembly. The uncertainty of rDNA genomic structure presents a significant barrier for studying their function and evolution. RESULTS Here we generate ultra-long Oxford Nanopore Technologies (ONT) and short NGS reads to delineate the architecture and variation of the 5S rDNA cluster in the different strains of C. elegans and C. briggsae. We classify the individual rDNA's repeating units into 25 types based on the unique sequence variations in each unit of C. elegans (N2). We next perform assembly of the cluster by taking advantage of the long reads that carry these units, which led to an assembly of 5S rDNA cluster consisting of up to 167 consecutive 5S rDNA units in the N2 strain. The ordering and copy number of various rDNA units are consistent with the separation time between strains. Surprisingly, we observed a drastically reduced level of variation in the unit composition in the 5S rDNA cluster in the C. elegans CB4856 and C. briggsae AF16 strains than in the C. elegans N2 strain, suggesting that N2, a widely used reference strain, is likely to be defective in maintaining the 5S rDNA cluster stability compared with other wild isolates of C. elegans or C. briggsae. CONCLUSIONS The results demonstrate that Nanopore DNA sequencing reads are capable of generating assembly of highly repetitive sequences, and rDNA units are highly dynamic both within and between population(s) of the same species in terms of sequence and copy number. The detailed structure and variation of the 5S rDNA units within the rDNA cluster pave the way for functional and evolutionary studies.
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Affiliation(s)
- Qiutao Ding
- Department of Biology, Hong Kong Baptist University, Hong Kong SAR, China
| | - Runsheng Li
- Department of Biology, Hong Kong Baptist University, Hong Kong SAR, China
- Department of Infectious Diseases and Public Health, City University of Hong Kong, Hong Kong SAR, China
| | - Xiaoliang Ren
- Department of Biology, Hong Kong Baptist University, Hong Kong SAR, China
| | - Lu-Yan Chan
- Department of Biology, Hong Kong Baptist University, Hong Kong SAR, China
| | - Vincy W S Ho
- Department of Biology, Hong Kong Baptist University, Hong Kong SAR, China
| | - Dongying Xie
- Department of Biology, Hong Kong Baptist University, Hong Kong SAR, China
| | - Pohao Ye
- Department of Biology, Hong Kong Baptist University, Hong Kong SAR, China
| | - Zhongying Zhao
- Department of Biology, Hong Kong Baptist University, Hong Kong SAR, China.
- State Key Laboratory of Environmental and Biological Analysis, Hong Kong Baptist University, Hong Kong SAR, China.
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21
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Hall AN, Morton E, Queitsch C. First discovered, long out of sight, finally visible: ribosomal DNA. Trends Genet 2022; 38:587-597. [PMID: 35272860 PMCID: PMC10132741 DOI: 10.1016/j.tig.2022.02.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Revised: 02/08/2022] [Accepted: 02/09/2022] [Indexed: 10/18/2022]
Abstract
With the advent of long-read sequencing, previously unresolvable genomic elements are being revisited in an effort to generate fully complete reference genomes. One such element is ribosomal DNA (rDNA), the highly conserved genomic region that encodes rRNAs. Genomic structure and content of the rDNA are variable in both prokarya and eukarya, posing interesting questions about the biology of rDNA. Here, we consider the types of variation observed in rDNA - including locus structure and number, copy number, and sequence variation - and their known phenotypic consequences. With recent advances in long-read sequencing technology, incorporating the full rDNA sequence into reference genomes is within reach. This knowledge will have important implications for understanding rDNA biology within the context of cell physiology and whole-organism phenotypes.
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22
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Kasselimi E, Pefani DE, Taraviras S, Lygerou Z. Ribosomal DNA and the nucleolus at the heart of aging. Trends Biochem Sci 2022; 47:328-341. [DOI: 10.1016/j.tibs.2021.12.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Revised: 12/15/2021] [Accepted: 12/16/2021] [Indexed: 12/15/2022]
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23
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Haig D. Concerted evolution of ribosomal DNA: Somatic peace amid germinal strife: Intranuclear and cellular selection maintain the quality of rRNA. Bioessays 2021; 43:e2100179. [PMID: 34704616 DOI: 10.1002/bies.202100179] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Accepted: 10/12/2021] [Indexed: 11/10/2022]
Abstract
Most eukaryotes possess many copies of rDNA. Organismal selection alone cannot maintain rRNA function because the effects of mutations in one rDNA are diluted by the presence of many other rDNAs. rRNA quality is maintained by processes that increase homogeneity of rRNA within, and heterogeneity among, germ cells thereby increasing the effectiveness of cellular selection on ribosomal function. A successful rDNA repeat will possess adaptations for spreading within tandem arrays by intranuclear selection. These adaptations reside in the non-coding regions of rDNA. Single-copy genes are predicted to manage processes of intranuclear and cellular selection in the germline to maintain the quality of rRNA expressed in somatic cells of future generations.
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Affiliation(s)
- David Haig
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts, USA
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24
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Cao X, Wang S, Ge L, Zhang W, Huang J, Sun W. Extrachromosomal Circular DNA: Category, Biogenesis, Recognition, and Functions. Front Vet Sci 2021; 8:693641. [PMID: 34568472 PMCID: PMC8458813 DOI: 10.3389/fvets.2021.693641] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2021] [Accepted: 07/30/2021] [Indexed: 12/17/2022] Open
Abstract
Extrachromosomal circular DNA (eccDNA), existing as double-stranded circular DNA, is derived and free from chromosomes. It is common in eukaryotes but has a strong heterogeneity in count, length, and origin. It has been demonstrated that eccDNA could function in telomere and rDNA maintenance, aging, drug resistance, tumorigenesis, and phenotypic variations of plants and animals. Here we review the current knowledge about eccDNA in category, biogenesis, recognition, and functions. We also provide perspectives on the potential implications of eccDNA in life science.
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Affiliation(s)
- Xiukai Cao
- Joint International Research Laboratory of Agriculture and Agri-Product Safety of Ministry of Education of China, Yangzhou University, Yangzhou, China
| | - Shan Wang
- College of Animal Science and Technology, Yangzhou University, Yangzhou, China
| | - Ling Ge
- College of Animal Science and Technology, Yangzhou University, Yangzhou, China
| | - Weibo Zhang
- College of Animal Science and Technology, Yangzhou University, Yangzhou, China
| | - Jinlin Huang
- Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou, China
| | - Wei Sun
- Joint International Research Laboratory of Agriculture and Agri-Product Safety of Ministry of Education of China, Yangzhou University, Yangzhou, China.,College of Animal Science and Technology, Yangzhou University, Yangzhou, China
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25
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Catania F, Ujvari B, Roche B, Capp JP, Thomas F. Bridging Tumorigenesis and Therapy Resistance With a Non-Darwinian and Non-Lamarckian Mechanism of Adaptive Evolution. Front Oncol 2021; 11:732081. [PMID: 34568068 PMCID: PMC8462274 DOI: 10.3389/fonc.2021.732081] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Accepted: 08/25/2021] [Indexed: 12/13/2022] Open
Abstract
Although neo-Darwinian (and less often Lamarckian) dynamics are regularly invoked to interpret cancer's multifarious molecular profiles, they shine little light on how tumorigenesis unfolds and often fail to fully capture the frequency and breadth of resistance mechanisms. This uncertainty frames one of the most problematic gaps between science and practice in modern times. Here, we offer a theory of adaptive cancer evolution, which builds on a molecular mechanism that lies outside neo-Darwinian and Lamarckian schemes. This mechanism coherently integrates non-genetic and genetic changes, ecological and evolutionary time scales, and shifts the spotlight away from positive selection towards purifying selection, genetic drift, and the creative-disruptive power of environmental change. The surprisingly simple use-it or lose-it rationale of the proposed theory can help predict molecular dynamics during tumorigenesis. It also provides simple rules of thumb that should help improve therapeutic approaches in cancer.
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Affiliation(s)
- Francesco Catania
- Institute for Evolution and Biodiversity, University of Münster, Münster, Germany
| | - Beata Ujvari
- Centre for Integrative Ecology, School of Life and Environmental Sciences, Deakin University, Deakin, VIC, Australia
| | - Benjamin Roche
- CREEC/CANECEV, MIVEGEC (CREES), Centre de Recherches Ecologiques et Evolutives sur le Cancer, University of Montpellier, CNRS, IRD, Montpellier, France
| | - Jean-Pascal Capp
- Toulouse Biotechnology Institute, University of Toulouse, INSA, CNRS, INRAE, Toulouse, France
| | - Frédéric Thomas
- CREEC/CANECEV, MIVEGEC (CREES), Centre de Recherches Ecologiques et Evolutives sur le Cancer, University of Montpellier, CNRS, IRD, Montpellier, France
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26
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Ling X, Han Y, Meng J, Zhong B, Chen J, Zhang H, Qin J, Pang J, Liu L. Small extrachromosomal circular DNA (eccDNA): major functions in evolution and cancer. Mol Cancer 2021; 20:113. [PMID: 34479546 PMCID: PMC8414719 DOI: 10.1186/s12943-021-01413-8] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Accepted: 08/22/2021] [Indexed: 12/13/2022] Open
Abstract
Extrachromosomal circular DNA (eccDNA) refers to a type of circular DNA that originate from but are likely independent of chromosomes. Due to technological advancements, eccDNAs have recently emerged as multifunctional molecules with numerous characteristics. The unique topological structure and genetic characteristics of eccDNAs shed new light on the monitoring, early diagnosis, treatment, and prediction of cancer. EccDNAs are commonly observed in both normal and cancer cells and function via different mechanisms in the stress response to exogenous and endogenous stimuli, aging, and carcinogenesis and in drug resistance during cancer treatment. The structural diversity of eccDNAs contributes to the function and numerical diversity of eccDNAs and thereby endows eccDNAs with powerful roles in evolution and in cancer initiation and progression by driving genetic plasticity and heterogeneity from extrachromosomal sites, which has been an ignored function in evolution in recent decades. EccDNAs show great potential in cancer, and we summarize the features, biogenesis, evaluated functions, functional mechanisms, related methods, and clinical utility of eccDNAs with a focus on their role in evolution and cancer.
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Affiliation(s)
- Xiaoxuan Ling
- Dongguan Key Laboratory of Environmental Medicine, School of Public Health, Guangdong Medical University, Dongguan, 523808, P.R. China
| | - Yali Han
- Dongguan Key Laboratory of Environmental Medicine, School of Public Health, Guangdong Medical University, Dongguan, 523808, P.R. China
| | - Jinxue Meng
- Dongguan Key Laboratory of Environmental Medicine, School of Public Health, Guangdong Medical University, Dongguan, 523808, P.R. China
| | - Bohuan Zhong
- Dongguan Key Laboratory of Environmental Medicine, School of Public Health, Guangdong Medical University, Dongguan, 523808, P.R. China
| | - Jialong Chen
- Dongguan Key Laboratory of Environmental Medicine, School of Public Health, Guangdong Medical University, Dongguan, 523808, P.R. China.,Department of Preventive Medicine, School of Public Health, Guangdong Medical University, Dongguan, 523808, P.R. China
| | - He Zhang
- Dongguan Key Laboratory of Environmental Medicine, School of Public Health, Guangdong Medical University, Dongguan, 523808, P.R. China.,Department of Preventive Medicine, School of Public Health, Guangdong Medical University, Dongguan, 523808, P.R. China
| | - Jiheng Qin
- Dongguan Key Laboratory of Environmental Medicine, School of Public Health, Guangdong Medical University, Dongguan, 523808, P.R. China
| | - Jing Pang
- Dongguan Key Laboratory of Environmental Medicine, School of Public Health, Guangdong Medical University, Dongguan, 523808, P.R. China
| | - Linhua Liu
- Dongguan Key Laboratory of Environmental Medicine, School of Public Health, Guangdong Medical University, Dongguan, 523808, P.R. China. .,Department of Preventive Medicine, School of Public Health, Guangdong Medical University, Dongguan, 523808, P.R. China.
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27
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Lou J, Yu S, Feng L, Guo X, Wang M, Branco AT, Li T, Lemos B. Environmentally induced ribosomal DNA (rDNA) instability in human cells and populations exposed to hexavalent chromium [Cr (VI)]. ENVIRONMENT INTERNATIONAL 2021; 153:106525. [PMID: 33774497 PMCID: PMC8477438 DOI: 10.1016/j.envint.2021.106525] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2021] [Revised: 03/09/2021] [Accepted: 03/11/2021] [Indexed: 05/12/2023]
Abstract
Hexavalent Chromium [Cr (VI)] is an established toxicant, carcinogen, and a significant source of public health concern. The multicopy ribosomal DNA (rDNA) array is mechanistically linked to aging and cancer, is the most evolutionarily conserved segment of the human genome, and gives origin to nucleolus, a nuclear organelle where ribosomes are assembled. Here we show that exposure to Cr (VI) induces instability in the rDNA, triggering cycles of rapid, specific, and transient amplification and contraction of the array in human cells. The dynamic of environmentally responsive rDNA copy number (CN) amplification and contraction occurs at doses to which millions of individuals are regularly exposed. Finally, analyses of human populations occupationally exposed to Cr (VI) indicate that environmental exposure history and drinking habits but not age shape extensive naturally occurring rDNA copy number variation. Our observations identify a novel pathway of response to hexavalent chromium exposure and raise the prospect that a suite of environmental determinants of rDNA copy number remain to be discovered.
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Affiliation(s)
- Jianlin Lou
- Program in Molecular and Integrative Physiological Sciences & Department of Environmental Health, Harvard T. H. Chan School of Public Health, Boston, MA, USA; School of Public Health, Hangzhou Medical College, Hangzhou, People's Republic of China; Institute of Occupational Diseases, Zhejiang Academy of Medical Sciences, Hangzhou, People's Republic of China
| | - Shoukai Yu
- Program in Molecular and Integrative Physiological Sciences & Department of Environmental Health, Harvard T. H. Chan School of Public Health, Boston, MA, USA
| | - Lingfang Feng
- School of Public Health, Hangzhou Medical College, Hangzhou, People's Republic of China; Institute of Occupational Diseases, Zhejiang Academy of Medical Sciences, Hangzhou, People's Republic of China
| | - Xinnian Guo
- School of Public Health, Hangzhou Medical College, Hangzhou, People's Republic of China; Institute of Occupational Diseases, Zhejiang Academy of Medical Sciences, Hangzhou, People's Republic of China
| | - Meng Wang
- Program in Molecular and Integrative Physiological Sciences & Department of Environmental Health, Harvard T. H. Chan School of Public Health, Boston, MA, USA
| | - Alan T Branco
- Program in Molecular and Integrative Physiological Sciences & Department of Environmental Health, Harvard T. H. Chan School of Public Health, Boston, MA, USA
| | - Tao Li
- School of Public Health, Hangzhou Medical College, Hangzhou, People's Republic of China; Institute of Occupational Diseases, Zhejiang Academy of Medical Sciences, Hangzhou, People's Republic of China
| | - Bernardo Lemos
- Program in Molecular and Integrative Physiological Sciences & Department of Environmental Health, Harvard T. H. Chan School of Public Health, Boston, MA, USA.
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28
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Pérez-Ortín JE, Mena A, Barba-Aliaga M, Singh A, Chávez S, García-Martínez J. Cell volume homeostatically controls the rDNA repeat copy number and rRNA synthesis rate in yeast. PLoS Genet 2021; 17:e1009520. [PMID: 33826644 PMCID: PMC8055003 DOI: 10.1371/journal.pgen.1009520] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Revised: 04/19/2021] [Accepted: 03/25/2021] [Indexed: 01/20/2023] Open
Abstract
The adjustment of transcription and translation rates to the changing needs of cells is of utmost importance for their fitness and survival. We have previously shown that the global transcription rate for RNA polymerase II in budding yeast Saccharomyces cerevisiae is regulated in relation to cell volume. Total mRNA concentration is constant with cell volume since global RNApol II-dependent nascent transcription rate (nTR) also keeps constant but mRNA stability increases with cell size. In this paper, we focus on the case of rRNA and RNA polymerase I. Contrarily to that found for RNA pol II, we detected that RNA polymerase I nTR increases proportionally to genome copies and cell size in polyploid cells. In haploid mutant cells with larger cell sizes, the rDNA repeat copy number rises. By combining mathematical modeling and experimental work with the large-size cln3 strain, we observed that the increasing repeat copy number is based on a feedback mechanism in which Sir2 histone deacetylase homeostatically controls the amplification of rDNA repeats in a volume-dependent manner. This amplification is paralleled with an increase in rRNA nTR, which indicates a control of the RNA pol I synthesis rate by cell volume. Synthesis rates of biological macromolecules should be strictly regulated and adjusted to the changing conditions of cells. The change in volume is one of the commonest variables along individual cell life and also when comparing different cell types. We previously found that cells with asymmetric division, such as budding yeasts, use a compensatory change in the global RNA polymerase II synthesis rate and mRNA decay rate to maintain mRNA homeostasis. In the present study, we address the same issue for the RNA polymerase that makes rRNAs, which are essential components of ribosomes and the most abundant RNAs in the cell. We found that the copy number of the gene encoding 35S rRNA, transcribed by RNA polymerase I, changes proportionally to the cell volume in budding yeast via a feedback mechanism based on the Sir2 histone deacetylase, which guarantees that yeast cells have the appropriate RNA polymerase I synthesis rate required for rRNA homeostasis.
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Affiliation(s)
- José E. Pérez-Ortín
- Instituto de Biotecnología y Biomedicina (Biotecmed), Universitat de València, Burjassot, Spain
- * E-mail: (JEP-O); (JG-M)
| | - Adriana Mena
- Instituto de Biotecnología y Biomedicina (Biotecmed), Universitat de València, Burjassot, Spain
| | - Marina Barba-Aliaga
- Instituto de Biotecnología y Biomedicina (Biotecmed), Universitat de València, Burjassot, Spain
| | - Abhyudai Singh
- Department of Electrical and Computer Engineering, University of Delaware, Newark, DE, United States of America
| | - Sebastián Chávez
- Instituto de Biomedicina de Sevilla. Campus Hospital Universitario Virgen del Rocío, Seville, Spain
| | - José García-Martínez
- Instituto de Biotecnología y Biomedicina (Biotecmed), Universitat de València, Burjassot, Spain
- * E-mail: (JEP-O); (JG-M)
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29
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Çalıseki M, Üstüntanır Dede AF, Arslanyolu M. Characterization and use of Tetrahymena thermophila artificial chromosome 2 (TtAC2) constructed by biomimetic of macronuclear rDNA minichromosome. Microbiol Res 2021; 248:126764. [PMID: 33887535 DOI: 10.1016/j.micres.2021.126764] [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: 02/03/2021] [Revised: 03/25/2021] [Accepted: 03/31/2021] [Indexed: 11/26/2022]
Abstract
Efficient expression vectors for unicellular ciliate eukaryotic Tetrahymena thermophila are still needed in recombinant biology and biotechnology applications. Previously, the construction of the T. thermophila Macronuclear Artificial Chromosome 1 (TtAC1) vector revealed additional needs for structural improvements such as better in vivo stability and maintenance as a recombinant protein expression platform. In this study, we designed an efficiently maintained artificial chromosome by biomimetic of the native macronuclear rDNA minichromosome. TtAC2 was constructed by sequential cloning of subtelomeric 3'NTS region (1.8 kb), an antibiotic resistance gene cassette (2 kb neo4), a gene expression cassette (2 kb TtsfGFP), rDNA coding regions plus a dominant C3 origin sequence (10.3 kb), and telomeres (2.4 kb) in a pUC19 backbone plasmid (2.6 kb). The 21 kb TtAC2 was characterized using fluorescence microscopy, qPCR, western blot and Southern blot after its transformation to vegetative T. thermophila CU428.2 strain, which has a recessive B origin allele. All experimental data show that circular or linear forms of novel TtAC2 were maintained as free replicons in T. thermophila macronucleus with or without antibiotic treatment. Notably, TtAC2 carrying strains expressed a TtsfGFP marker protein, demonstrating the efficacy and functionality of the protein expression platform. We show that TtAC2 is functionally maintained for more than two months, and can be efficiently used in recombinant DNA, and protein production applications.
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Affiliation(s)
- Mehmet Çalıseki
- Department of Advanced Technologies, Graduate School of Sciences, Eskisehir Technical University, Yunusemre Campus, Eskisehir, 26470, Turkey.
| | - Ayça Fulya Üstüntanır Dede
- Department of Biology, Institute of Graduate Programs, Eskisehir Technical University, Yunusemre Campus, Eskisehir, 26470, Turkey.
| | - Muhittin Arslanyolu
- Department of Biology, Faculty of Sciences, Eskisehir Technical University, Yunusemre Campus, Eskisehir, 26470, Turkey.
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30
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Salim D, Bradford WD, Rubinstein B, Gerton JL. DNA replication, transcription, and H3K56 acetylation regulate copy number and stability at tandem repeats. G3-GENES GENOMES GENETICS 2021; 11:6174693. [PMID: 33729510 DOI: 10.1093/g3journal/jkab082] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Accepted: 02/26/2021] [Indexed: 11/13/2022]
Abstract
Tandem repeats are inherently unstable and exhibit extensive copy number polymorphisms. Despite mounting evidence for their adaptive potential, the mechanisms associated with regulation of the stability and copy number of tandem repeats remain largely unclear. To study copy number variation at tandem repeats, we used two well-studied repetitive arrays in the budding yeast genome, the ribosomal DNA (rDNA) locus, and the copper-inducible CUP1 gene array. We developed powerful, highly sensitive, and quantitative assays to measure repeat instability and copy number and used them in multiple high-throughput genetic screens to define pathways involved in regulating copy number variation. These screens revealed that rDNA stability and copy number are regulated by DNA replication, transcription, and histone acetylation. Through parallel studies of both arrays, we demonstrate that instability can be induced by DNA replication stress and transcription. Importantly, while changes in stability in response to stress are observed within a few cell divisions, a change in steady state repeat copy number requires selection over time. Further, H3K56 acetylation is required for regulating transcription and transcription-induced instability at the CUP1 array, and restricts transcription-induced amplification. Our work suggests that the modulation of replication and transcription is a direct, reversible strategy to alter stability at tandem repeats in response to environmental stimuli, which provides cells rapid adaptability through copy number variation. Additionally, histone acetylation may function to promote the normal adaptive program in response to transcriptional stress. Given the omnipresence of DNA replication, transcription, and chromatin marks like histone acetylation, the fundamental mechanisms we have uncovered significantly advance our understanding of the plasticity of tandem repeats more generally.
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Affiliation(s)
- Devika Salim
- Stowers Institute for Medical Research, Kansas City, MO 64110, United States of America.,Open University, Milton Keynes MK7 6BJ, United Kingdom
| | - William D Bradford
- Stowers Institute for Medical Research, Kansas City, MO 64110, United States of America
| | - Boris Rubinstein
- Stowers Institute for Medical Research, Kansas City, MO 64110, United States of America
| | - Jennifer L Gerton
- Stowers Institute for Medical Research, Kansas City, MO 64110, United States of America.,Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, Kansas City, KS 66160, United States of America
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31
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The extrachromosomal elements of the Naegleria genus: How little we know. Plasmid 2021; 115:102567. [PMID: 33617907 DOI: 10.1016/j.plasmid.2021.102567] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2020] [Revised: 02/05/2021] [Accepted: 02/10/2021] [Indexed: 11/20/2022]
Abstract
There are currently 47 characterized species in the Naegleria genus of free-living amoebae. Each amoeba has thousands of extrachromosomal elements that are closed circular structures comprised of a single ribosomal DNA (rDNA) copy and a large non-rDNA sequence. Despite the presence of putative open reading frames and introns, ribosomal RNA is the only established transcript. A single origin of DNA replication (ori) has been mapped within the non-rDNA sequence for one species (N. gruberi), a finding that strongly indicates that these episomes replicate independently of the cell's chromosomal DNA component. This article reviews that which has been published about these interesting DNA elements and by analyzing available sequence data, discusses the possibility that different phylogenetically related clusters of Naegleria species individually conserve ori structures and suggests where the rRNA promoter and termination sites may be located.
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32
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Liang X, Chen H, Li L, An R, Komiyama M. Ring-Structured DNA and RNA as Key Players In Vivoand In Vitro. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2021. [DOI: 10.1246/bcsj.20200235] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- Xingguo Liang
- College of Food Science and Engineering, Ocean University of China, Qingdao 266003, P. R. China
- Laboratory for Marine Drugs and Bioproducts of Qingdao National Laboratory for Marine Science and Technology, Qingdao 266235, P. R. China
| | - Hui Chen
- College of Food Science and Engineering, Ocean University of China, Qingdao 266003, P. R. China
| | - Lin Li
- College of Food Science and Engineering, Ocean University of China, Qingdao 266003, P. R. China
| | - Ran An
- College of Food Science and Engineering, Ocean University of China, Qingdao 266003, P. R. China
| | - Makoto Komiyama
- College of Food Science and Engineering, Ocean University of China, Qingdao 266003, P. R. China
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33
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Shi S, Luo H, Wang L, Li H, Liang Y, Xia J, Wang Z, Cheng B, Huang L, Liao G, Xu B. Combined inhibition of RNA polymerase I and mTORC1/2 synergize to combat oral squamous cell carcinoma. Biomed Pharmacother 2021; 133:110906. [PMID: 33190037 DOI: 10.1016/j.biopha.2020.110906] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2020] [Revised: 10/13/2020] [Accepted: 10/16/2020] [Indexed: 01/27/2023] Open
Abstract
Oral squamous cell carcinoma (OSCC) is the major cause of morbidity and mortality in head and neck cancer patients worldwide. This malignant disease is challenging to treat because of the lack of effective curative strategies and the high incidence of recurrence. This study aimed to investigate the efficacy of a single and dual approach targeting ribosome biogenesis and protein translation to treat OSCC associated with the copy number variation (CNV) of ribosomal DNA (rDNA). Here, we found that primary OSCC tumors frequently exhibited a partial loss of 45S rDNA copy number and demonstrated a high susceptibility to CX5461 (a selective inhibitor of RNA polymerase I) and the coadministration of CX5461 and INK128 (a potent inhibitor of mTORC1/2). Combined treatment displayed the promising synergistic effects that induced cell apoptosis and reactive oxygen species (ROS) generation, and inhibited cell growth and proliferation. Moreover, INK128 compromised NHEJ-DNA repair pathway to reinforce the antitumor activity of CX5461. In vivo, the cotreatment synergistically suppressed tumor growth, triggered apoptosis and strikingly extended the survival time of tumor-bearing mice. Additionally, treatment with the individual compounds and coadministration appeared to reduce the incidence of enlarged inguinal lymph nodes. Our study supports that the combination of CX5461 and INK128 is a novel and efficacious therapeutic strategy that can combat this cancer and that 45S rDNA may serve as a useful indicator to predict the efficacy of this cotreatment.
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Affiliation(s)
- Shanwei Shi
- Hospital of Stomatology, Guangdong Provincial Key Laboratory of Stomatology, Guanghua School of Stomatology, Institute of Stomatological Research, Sun Yat-sen University, Guangzhou, Guangdong Province, China
| | - Huigen Luo
- Hospital of Stomatology, Guangdong Provincial Key Laboratory of Stomatology, Guanghua School of Stomatology, Institute of Stomatological Research, Sun Yat-sen University, Guangzhou, Guangdong Province, China
| | - Lihong Wang
- Hospital of Stomatology, Guangdong Provincial Key Laboratory of Stomatology, Guanghua School of Stomatology, Institute of Stomatological Research, Sun Yat-sen University, Guangzhou, Guangdong Province, China
| | - Hua Li
- The Stowers Institute for Medical Research, Kansas City, Missouri, United States
| | - Yujie Liang
- Hospital of Stomatology, Guangdong Provincial Key Laboratory of Stomatology, Guanghua School of Stomatology, Institute of Stomatological Research, Sun Yat-sen University, Guangzhou, Guangdong Province, China
| | - Juan Xia
- Hospital of Stomatology, Guangdong Provincial Key Laboratory of Stomatology, Guanghua School of Stomatology, Institute of Stomatological Research, Sun Yat-sen University, Guangzhou, Guangdong Province, China
| | - Zhi Wang
- Hospital of Stomatology, Guangdong Provincial Key Laboratory of Stomatology, Guanghua School of Stomatology, Institute of Stomatological Research, Sun Yat-sen University, Guangzhou, Guangdong Province, China
| | - Bin Cheng
- Hospital of Stomatology, Guangdong Provincial Key Laboratory of Stomatology, Guanghua School of Stomatology, Institute of Stomatological Research, Sun Yat-sen University, Guangzhou, Guangdong Province, China
| | - Linfeng Huang
- Division of Natural and Applied Sciences, Duke Kunshan University, Kunshan, Jiangsu, China
| | - Guiqing Liao
- Hospital of Stomatology, Guangdong Provincial Key Laboratory of Stomatology, Guanghua School of Stomatology, Institute of Stomatological Research, Sun Yat-sen University, Guangzhou, Guangdong Province, China.
| | - Baoshan Xu
- Hospital of Stomatology, Guangdong Provincial Key Laboratory of Stomatology, Guanghua School of Stomatology, Institute of Stomatological Research, Sun Yat-sen University, Guangzhou, Guangdong Province, China.
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34
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Excessive rDNA Transcription Drives the Disruption in Nuclear Homeostasis during Entry into Senescence in Budding Yeast. Cell Rep 2020; 28:408-422.e4. [PMID: 31291577 DOI: 10.1016/j.celrep.2019.06.032] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Revised: 04/09/2019] [Accepted: 06/07/2019] [Indexed: 01/11/2023] Open
Abstract
Budding yeast cells undergo a limited number of divisions before they enter senescence and die. Despite recent mechanistic advances, whether and how molecular events are temporally and causally linked during the transition to senescence remain elusive. Here, using real-time observation of the accumulation of extrachromosomal rDNA circles (ERCs) in single cells, we provide evidence that ERCs build up rapidly with exponential kinetics well before any physiological decline. We then show that ERCs fuel a massive increase in ribosomal RNA (rRNA) levels in the nucleolus, which do not mature into functional ribosomes. This breakdown in nucleolar coordination is followed by a loss of nuclear homeostasis, thus defining a chronology of causally related events leading to cell death. A computational analysis supports a model in which a series of age-independent processes lead to an age-dependent increase in cell mortality, hence explaining the emergence of aging in budding yeast.
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35
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Yan Y, Guo G, Huang J, Gao M, Zhu Q, Zeng S, Gong Z, Xu Z. Current understanding of extrachromosomal circular DNA in cancer pathogenesis and therapeutic resistance. J Hematol Oncol 2020; 13:124. [PMID: 32928268 PMCID: PMC7491193 DOI: 10.1186/s13045-020-00960-9] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Accepted: 09/03/2020] [Indexed: 02/08/2023] Open
Abstract
Extrachromosomal circular DNA was recently found to be particularly abundant in multiple human cancer cells, although its frequency varies among different tumor types. Elevated levels of extrachromosomal circular DNA have been considered an effective biomarker of cancer pathogenesis. Multiple reports have demonstrated that the amplification of oncogenes and therapeutic resistance genes located on extrachromosomal DNA is a frequent event that drives intratumoral genetic heterogeneity and provides a potential evolutionary advantage. This review highlights the current understanding of the extrachromosomal circular DNA present in the tissues and circulation of patients with advanced cancers and provides a detailed discussion of their substantial roles in tumor regulation. Confirming the presence of cancer-related extrachromosomal circular DNA would provide a putative testing strategy for the precision diagnosis and treatment of human malignancies in clinical practice.
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Affiliation(s)
- Yuanliang Yan
- Department of Pharmacy, Xiangya Hospital, Central South University, Changsha, 410008, Hunan, China.,Department of Oncology, Mayo Clinic, Rochester, MN, 55905, USA
| | - Guijie Guo
- Department of Oncology, Mayo Clinic, Rochester, MN, 55905, USA
| | - Jinzhou Huang
- Department of Oncology, Mayo Clinic, Rochester, MN, 55905, USA
| | - Ming Gao
- Department of Oncology, Mayo Clinic, Rochester, MN, 55905, USA
| | - Qian Zhu
- Department of Oncology, Mayo Clinic, Rochester, MN, 55905, USA
| | - Shuangshuang Zeng
- Department of Pharmacy, Xiangya Hospital, Central South University, Changsha, 410008, Hunan, China
| | - Zhicheng Gong
- Department of Pharmacy, Xiangya Hospital, Central South University, Changsha, 410008, Hunan, China
| | - Zhijie Xu
- Department of Pathology, Xiangya Hospital, Central South University, Changsha, 410008, Hunan, China. .,National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, 410008, Hunan, China.
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36
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Harvey EF, Cristescu ME, Dale J, Hunter H, Randall C, Crease TJ. Metal exposure causes rDNA copy number to fluctuate in mutation accumulation lines of Daphnia pulex. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2020; 226:105556. [PMID: 32652413 DOI: 10.1016/j.aquatox.2020.105556] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Revised: 05/29/2020] [Accepted: 06/26/2020] [Indexed: 06/11/2023]
Abstract
Ribosomal (r)DNA is a highly dynamic, conserved, multigene family whose sequence homogeneity is thought to be maintained by intra- and interchromosomal recombination, which are capable of changing rDNA copy number. It is generally not known how environmental stress such as sublethal exposure to environmentally relevant concentrations of metals impacts rDNA copy number. To determine how chronic metal exposure affects rDNA, we measured copy number of the 18S rRNA gene in 355 copper and nickel-exposed samples and 132 metal-free samples derived from 325 mutation accumulation (MA) lines of two genetically distinct Daphnia pulex lineages. The MA lines were sampled at four time points over 100+ generations of clonal propagation. The copy number of rDNA was also measured in 15 individuals sampled from a metal-free non-MA control population established from the same progenitor as one of the MA lineages. We found that mean rDNA copy number fluctuated across lines exposed to metals with a tendency to decrease over time. In contrast, mean rDNA copy number in the metal-free control lines and the non-MA population remained stable over time. It is generally accepted that extreme rDNA loss results in the loss of organism fitness. Thus, fluctuations in rDNA copy number, including losses, could affect the long-term viability of natural populations of Daphnia in metal-contaminated habitats.
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Affiliation(s)
- Eleanor F Harvey
- Department of Integrative Biology, University of Guelph, 50 Stone Road West, Guelph, ON, N1G 2W1, Canada
| | - Melania E Cristescu
- Biology Department, McGill University, Stewart Biology Building, 1205 Dr Penfield Ave, Montreal, QC, H3A 1B1, Canada
| | - Jenna Dale
- Department of Integrative Biology, University of Guelph, 50 Stone Road West, Guelph, ON, N1G 2W1, Canada
| | - Hailey Hunter
- Department of Integrative Biology, University of Guelph, 50 Stone Road West, Guelph, ON, N1G 2W1, Canada
| | - Connor Randall
- Department of Integrative Biology, University of Guelph, 50 Stone Road West, Guelph, ON, N1G 2W1, Canada
| | - Teresa J Crease
- Department of Integrative Biology, University of Guelph, 50 Stone Road West, Guelph, ON, N1G 2W1, Canada.
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37
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Prada-Luengo I, Møller HD, Henriksen RA, Gao Q, Larsen C, Alizadeh S, Maretty L, Houseley J, Regenberg B. Replicative aging is associated with loss of genetic heterogeneity from extrachromosomal circular DNA in Saccharomyces cerevisiae. Nucleic Acids Res 2020; 48:7883-7898. [PMID: 32609810 PMCID: PMC7430651 DOI: 10.1093/nar/gkaa545] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2019] [Revised: 05/28/2020] [Accepted: 06/17/2020] [Indexed: 12/26/2022] Open
Abstract
Circular DNA can arise from all parts of eukaryotic chromosomes. In yeast, circular ribosomal DNA (rDNA) accumulates dramatically as cells age, however little is known about the accumulation of other chromosome-derived circles or the contribution of such circles to genetic variation in aged cells. We profiled circular DNA in Saccharomyces cerevisiae populations sampled when young and after extensive aging. Young cells possessed highly diverse circular DNA populations but 94% of the circular DNA were lost after ∼15 divisions, whereas rDNA circles underwent massive accumulation to >95% of circular DNA. Circles present in both young and old cells were characterized by replication origins including circles from unique regions of the genome and repetitive regions: rDNA and telomeric Y' regions. We further observed that circles can have flexible inheritance patterns: [HXT6/7circle] normally segregates to mother cells but in low glucose is present in up to 50% of cells, the majority of which must have inherited this circle from their mother. Interestingly, [HXT6/7circle] cells are eventually replaced by cells carrying stable chromosomal HXT6 HXT6/7 HXT7 amplifications, suggesting circular DNAs are intermediates in chromosomal amplifications. In conclusion, the heterogeneity of circular DNA offers flexibility in adaptation, but this heterogeneity is remarkably diminished with age.
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Affiliation(s)
- Iñigo Prada-Luengo
- Ecology and Evolution, Department of Biology, University of Copenhagen, Copenhagen DK-2100, Denmark
| | - Henrik D Møller
- Ecology and Evolution, Department of Biology, University of Copenhagen, Copenhagen DK-2100, Denmark
- Department of Biology, Institute of Biochemistry, ETH Zürich, Zurich CH-8093, Switzerland
| | - Rasmus A Henriksen
- Ecology and Evolution, Department of Biology, University of Copenhagen, Copenhagen DK-2100, Denmark
| | - Qian Gao
- Epigenetics Programme, The Babraham Institute, Babraham, Cambridge CB22 3-AT, UK
- Adaptimmune Ltd, Oxfordshire OX14 4RX, UK
| | - Camilla Eggert Larsen
- Ecology and Evolution, Department of Biology, University of Copenhagen, Copenhagen DK-2100, Denmark
| | - Sefa Alizadeh
- Ecology and Evolution, Department of Biology, University of Copenhagen, Copenhagen DK-2100, Denmark
| | - Lasse Maretty
- Department of Molecular Medicine, Aarhus University Hospital, Aarhus DK-8200, Denmark
| | - Jonathan Houseley
- Epigenetics Programme, The Babraham Institute, Babraham, Cambridge CB22 3-AT, UK
| | - Birgitte Regenberg
- Ecology and Evolution, Department of Biology, University of Copenhagen, Copenhagen DK-2100, Denmark
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38
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Møller HD, Ramos-Madrigal J, Prada-Luengo I, Gilbert MTP, Regenberg B. Near-Random Distribution of Chromosome-Derived Circular DNA in the Condensed Genome of Pigeons and the Larger, More Repeat-Rich Human Genome. Genome Biol Evol 2020; 12:3762-3777. [PMID: 31882998 PMCID: PMC6993614 DOI: 10.1093/gbe/evz281] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/20/2019] [Indexed: 12/15/2022] Open
Abstract
Extrachromosomal circular DNA (eccDNA) elements of chromosomal origin are known to be common in a number of eukaryotic species. However, it remains to be addressed whether genomic features such as genome size, the load of repetitive elements within a genome, and/or animal physiology affect the number of eccDNAs. Here, we investigate the distribution and numbers of eccDNAs in a condensed and less repeat-rich genome compared with the human genome, using Columba livia domestica (domestic rock pigeon) as a model organism. By sequencing eccDNA in blood and breast muscle from three pigeon breeds at various ages and with different flight behavior, we characterize 30,000 unique eccDNAs. We identify genomic regions that are likely hotspots for DNA circularization in breast muscle, including genes involved in muscle development. We find that although eccDNA counts do not correlate with the biological age in pigeons, the number of unique eccDNAs in a nonflying breed (king pigeons) is significantly higher (9-fold) than homing pigeons. Furthermore, a comparison between eccDNA from skeletal muscle in pigeons and humans reveals ∼9-10 times more unique eccDNAs per human nucleus. The fraction of eccDNA sequences, derived from repetitive elements, exist in proportions to genome content, that is, human 72.4% (expected 52.5%) and pigeon 8.7% (expected 5.5%). Overall, our results support that eccDNAs are common in pigeons, that the amount of unique eccDNA types per nucleus can differ between species as well as subspecies, and suggest that eccDNAs from repeats are found in proportions relative to the content of repetitive elements in a genome.
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Affiliation(s)
- Henrik Devitt Møller
- Department of Biology, University of Copenhagen, Denmark.,Department of Biology, Institute of Biochemistry, ETH Zürich, Switzerland
| | | | | | - M Thomas P Gilbert
- The GLOBE Institute, University of Copenhagen, Denmark.,NTNU University Museum, Trondheim, Norway
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39
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Ain Q, Schmeer C, Wengerodt D, Witte OW, Kretz A. Extrachromosomal Circular DNA: Current Knowledge and Implications for CNS Aging and Neurodegeneration. Int J Mol Sci 2020; 21:E2477. [PMID: 32252492 PMCID: PMC7177960 DOI: 10.3390/ijms21072477] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Revised: 03/26/2020] [Accepted: 03/30/2020] [Indexed: 12/13/2022] Open
Abstract
Still unresolved is the question of how a lifetime accumulation of somatic gene copy number alterations impact organ functionality and aging and age-related pathologies. Such an issue appears particularly relevant in the broadly post-mitotic central nervous system (CNS), where non-replicative neurons are restricted in DNA-repair choices and are prone to accumulate DNA damage, as they remain unreplaced over a lifetime. Both DNA injuries and consecutive DNA-repair strategies are processes that can evoke extrachromosomal circular DNA species, apparently from either part of the genome. Due to their capacity to amplify gene copies and related transcripts, the individual cellular load of extrachromosomal circular DNAs will contribute to a dynamic pool of additional coding and regulatory chromatin elements. Analogous to tumor tissues, where the mosaicism of circular DNAs plays a well-characterized role in oncogene plasticity and drug resistance, we suggest involvement of the "circulome" also in the CNS. Accordingly, we summarize current knowledge on the molecular biogenesis, homeostasis and gene regulatory impacts of circular extrachromosomal DNA and propose, in light of recent discoveries, a critical role in CNS aging and neurodegeneration. Future studies will elucidate the influence of individual extrachromosomal DNA species according to their sequence complexity and regional distribution or cell-type-specific abundance.
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Affiliation(s)
- Quratul Ain
- Hans-Berger Department of Neurology, Jena University Hospital, 07747 Jena, Thuringia, Germany; (Q.A.); (C.S.); (D.W.); (O.W.W.)
| | - Christian Schmeer
- Hans-Berger Department of Neurology, Jena University Hospital, 07747 Jena, Thuringia, Germany; (Q.A.); (C.S.); (D.W.); (O.W.W.)
- Jena Center for Healthy Ageing, Jena University Hospital, 07747 Jena, Thuringia, Germany
| | - Diane Wengerodt
- Hans-Berger Department of Neurology, Jena University Hospital, 07747 Jena, Thuringia, Germany; (Q.A.); (C.S.); (D.W.); (O.W.W.)
| | - Otto W. Witte
- Hans-Berger Department of Neurology, Jena University Hospital, 07747 Jena, Thuringia, Germany; (Q.A.); (C.S.); (D.W.); (O.W.W.)
- Jena Center for Healthy Ageing, Jena University Hospital, 07747 Jena, Thuringia, Germany
| | - Alexandra Kretz
- Hans-Berger Department of Neurology, Jena University Hospital, 07747 Jena, Thuringia, Germany; (Q.A.); (C.S.); (D.W.); (O.W.W.)
- Jena Center for Healthy Ageing, Jena University Hospital, 07747 Jena, Thuringia, Germany
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40
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Hull RM, King M, Pizza G, Krueger F, Vergara X, Houseley J. Transcription-induced formation of extrachromosomal DNA during yeast ageing. PLoS Biol 2019; 17:e3000471. [PMID: 31794573 PMCID: PMC6890164 DOI: 10.1371/journal.pbio.3000471] [Citation(s) in RCA: 58] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Accepted: 10/31/2019] [Indexed: 12/22/2022] Open
Abstract
Extrachromosomal circular DNA (eccDNA) facilitates adaptive evolution by allowing rapid and extensive gene copy number variation and is implicated in the pathology of cancer and ageing. Here, we demonstrate that yeast aged under environmental copper accumulate high levels of eccDNA containing the copper-resistance gene CUP1. Transcription of the tandemly repeated CUP1 gene causes CUP1 eccDNA accumulation, which occurs in the absence of phenotypic selection. We have developed a sensitive and quantitative eccDNA sequencing pipeline that reveals CUP1 eccDNA accumulation on copper exposure to be exquisitely site specific, with no other detectable changes across the eccDNA complement. eccDNA forms de novo from the CUP1 locus through processing of DNA double-strand breaks (DSBs) by Sae2, Mre11 and Mus81, and genome-wide analyses show that other protein coding eccDNA species in aged yeast share a similar biogenesis pathway. Although abundant, we find that CUP1 eccDNA does not replicate efficiently, and high-copy numbers in aged cells arise through frequent formation events combined with asymmetric DNA segregation. The transcriptional stimulation of CUP1 eccDNA formation shows that age-linked genetic change varies with transcription pattern, resulting in gene copy number profiles tailored by environment. Transcription can cause the de novo formation of protein-coding extrachromosomal DNA that accumulates in ageing yeast cells; these extrachromosomal circular DNA molecules form frequently by a DNA double strand break repair mechanism.
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Affiliation(s)
- Ryan M. Hull
- Epigenetics Programme, Babraham Institute, Cambridge, United Kingdom
| | - Michelle King
- Epigenetics Programme, Babraham Institute, Cambridge, United Kingdom
| | - Grazia Pizza
- Epigenetics Programme, Babraham Institute, Cambridge, United Kingdom
| | - Felix Krueger
- Babraham Bioinformatics, Babraham Institute, Cambridge, United Kingdom
| | - Xabier Vergara
- Epigenetics Programme, Babraham Institute, Cambridge, United Kingdom
| | - Jonathan Houseley
- Epigenetics Programme, Babraham Institute, Cambridge, United Kingdom
- * E-mail:
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41
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Yerlici VT, Lu MW, Hoge CR, Miller RV, Neme R, Khurana JS, Bracht JR, Landweber LF. Programmed genome rearrangements in Oxytricha produce transcriptionally active extrachromosomal circular DNA. Nucleic Acids Res 2019; 47:9741-9760. [PMID: 31504770 PMCID: PMC6765146 DOI: 10.1093/nar/gkz725] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2019] [Revised: 08/02/2019] [Accepted: 08/20/2019] [Indexed: 11/13/2022] Open
Abstract
Extrachromosomal circular DNA (eccDNA) is both a driver of eukaryotic genome instability and a product of programmed genome rearrangements, but its extent had not been surveyed in Oxytricha, a ciliate with elaborate DNA elimination and translocation during development. Here, we captured rearrangement-specific circular DNA molecules across the genome to gain insight into its processes of programmed genome rearrangement. We recovered thousands of circularly excised Tc1/mariner-type transposable elements and high confidence non-repetitive germline-limited loci. We verified their bona fide circular topology using circular DNA deep-sequencing, 2D gel electrophoresis and inverse polymerase chain reaction. In contrast to the precise circular excision of transposable elements, we report widespread heterogeneity in the circular excision of non-repetitive germline-limited loci. We also demonstrate that circular DNAs are transcribed in Oxytricha, producing rearrangement-specific long non-coding RNAs. The programmed formation of thousands of eccDNA molecules makes Oxytricha a model system for studying nucleic acid topology. It also suggests involvement of eccDNA in programmed genome rearrangement.
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Affiliation(s)
- V Talya Yerlici
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA.,Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA
| | - Michael W Lu
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA.,Department of Biological Sciences, Columbia University, New York, NY 10027, USA
| | - Carla R Hoge
- Department of Biological Sciences, Columbia University, New York, NY 10027, USA
| | - Richard V Miller
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA.,Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA
| | - Rafik Neme
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - Jaspreet S Khurana
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - John R Bracht
- Department of Biology, American University, Washington, DC 20016, USA
| | - Laura F Landweber
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA.,Department of Biological Sciences, Columbia University, New York, NY 10027, USA
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42
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Puddu F, Herzog M, Selivanova A, Wang S, Zhu J, Klein-Lavi S, Gordon M, Meirman R, Millan-Zambrano G, Ayestaran I, Salguero I, Sharan R, Li R, Kupiec M, Jackson SP. Genome architecture and stability in the Saccharomyces cerevisiae knockout collection. Nature 2019; 573:416-420. [PMID: 31511699 PMCID: PMC6774800 DOI: 10.1038/s41586-019-1549-9] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2018] [Accepted: 08/07/2019] [Indexed: 02/07/2023]
Abstract
Despite major progress in defining the functional roles of genes, a complete understanding of their influences is far from being realized, even in relatively simple organisms. A major milestone in this direction arose via the completion of the yeast Saccharomyces cerevisiae gene-knockout collection (YKOC), which has enabled high-throughput reverse genetics, phenotypic screenings and analyses of synthetic-genetic interactions1-3. Ensuing experimental work has also highlighted some inconsistencies and mistakes in the YKOC, or genome instability events that rebalance the effects of specific knockouts4-6, but a complete overview of these is lacking. The identification and analysis of genes that are required for maintaining genomic stability have traditionally relied on reporter assays and on the study of deletions of individual genes, but whole-genome-sequencing technologies now enable-in principle-the direct observation of genome instability globally and at scale. To exploit this opportunity, we sequenced the whole genomes of nearly all of the 4,732 strains comprising the homozygous diploid YKOC. Here, by extracting information on copy-number variation of tandem and interspersed repetitive DNA elements, we describe-for almost every single non-essential gene-the genomic alterations that are induced by its loss. Analysis of this dataset reveals genes that affect the maintenance of various genomic elements, highlights cross-talks between nuclear and mitochondrial genome stability, and shows how strains have genetically adapted to life in the absence of individual non-essential genes.
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Affiliation(s)
- Fabio Puddu
- The Wellcome Trust/CRUK Gurdon Institute, University of Cambridge, Cambridge, UK.
- Department of Biochemistry, University of Cambridge, Cambridge, UK.
- Wellcome Sanger Institute, Hinxton, UK.
| | - Mareike Herzog
- The Wellcome Trust/CRUK Gurdon Institute, University of Cambridge, Cambridge, UK
- Department of Biochemistry, University of Cambridge, Cambridge, UK
- Wellcome Sanger Institute, Hinxton, UK
| | - Alexandra Selivanova
- The Wellcome Trust/CRUK Gurdon Institute, University of Cambridge, Cambridge, UK
- Department of Biochemistry, University of Cambridge, Cambridge, UK
| | - Siyue Wang
- The Wellcome Trust/CRUK Gurdon Institute, University of Cambridge, Cambridge, UK
- Department of Biochemistry, University of Cambridge, Cambridge, UK
| | - Jin Zhu
- Center for Cell Dynamics, Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Shir Klein-Lavi
- School of Molecular Cell Biology and Biotechnology, Tel Aviv University, Tel Aviv, Israel
| | - Molly Gordon
- Center for Cell Dynamics, Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Roi Meirman
- School of Molecular Cell Biology and Biotechnology, Tel Aviv University, Tel Aviv, Israel
| | - Gonzalo Millan-Zambrano
- The Wellcome Trust/CRUK Gurdon Institute, University of Cambridge, Cambridge, UK
- Department of Pathology, University of Cambridge, Cambridge, UK
| | - Iñigo Ayestaran
- The Wellcome Trust/CRUK Gurdon Institute, University of Cambridge, Cambridge, UK
- Department of Biochemistry, University of Cambridge, Cambridge, UK
| | - Israel Salguero
- The Wellcome Trust/CRUK Gurdon Institute, University of Cambridge, Cambridge, UK
- Department of Biochemistry, University of Cambridge, Cambridge, UK
| | - Roded Sharan
- School of Computer Science, Tel Aviv University, Tel Aviv, Israel
| | - Rong Li
- Center for Cell Dynamics, Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Martin Kupiec
- School of Molecular Cell Biology and Biotechnology, Tel Aviv University, Tel Aviv, Israel
| | - Stephen P Jackson
- The Wellcome Trust/CRUK Gurdon Institute, University of Cambridge, Cambridge, UK.
- Department of Biochemistry, University of Cambridge, Cambridge, UK.
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43
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Nelson JO, Watase GJ, Warsinger-Pepe N, Yamashita YM. Mechanisms of rDNA Copy Number Maintenance. Trends Genet 2019; 35:734-742. [PMID: 31395390 DOI: 10.1016/j.tig.2019.07.006] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Revised: 06/28/2019] [Accepted: 07/12/2019] [Indexed: 12/21/2022]
Abstract
rDNA, the genes encoding the RNA components of ribosomes (rRNA), are highly repetitive in all eukaryotic genomes, containing 100s to 1000s of copies, to meet the demand for ribosome biogenesis. rDNA genes are arranged in large stretches of tandem repeats, forming loci that are highly susceptible to copy loss due to their repetitiveness and active transcription throughout the cell cycle. Despite this inherent instability, rDNA copy number is generally maintained within a particular range in each species, pointing to the presence of mechanisms that maintain rDNA copy number in a homeostatic range. In this review, we summarize the current understanding of these maintenance mechanisms and how they sustain rDNA copy number throughout populations.
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Affiliation(s)
- Jonathan O Nelson
- Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA; Howard Hughes Medical Institute, University of Michigan, Ann Arbor, MI, USA
| | - George J Watase
- Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA; Howard Hughes Medical Institute, University of Michigan, Ann Arbor, MI, USA
| | - Natalie Warsinger-Pepe
- Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA; Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI, USA
| | - Yukiko M Yamashita
- Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA; Cell and Developmental Biology, University of Michigan, Ann Arbor, MI, USA; Howard Hughes Medical Institute, University of Michigan, Ann Arbor, MI, USA.
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44
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Tandon I, Pal R, Pal JK, Sharma NK. Extrachromosomal circular DNAs: an extra piece of evidence to depict tumor heterogeneity. Future Sci OA 2019; 5:FSO390. [PMID: 31285839 PMCID: PMC6609892 DOI: 10.2144/fsoa-2019-0024] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
The tumor microenvironment (TME) comprises a heterogeneous number and type of cellular and noncellular components that vary in the context of molecular, genomic and epigenomic levels. The genotypic diversity and plasticity within cancer cells are known to be affected by genomic instability and genome alterations. Besides genomic instability within the chromosomal linear DNA, an extra factor appears in the form of extrachromosomal circular DNAs (eccDNAs; 2-20 kbp) and microDNAs (200-400 bp). This extra heterogeneity within cancer cells in the form of an abundance of eccDNAs adds another dimension to the expression of procancer players, such as oncoproteins, acting as a driver for cancer cell survival and proliferation. This article reviews research into eccDNAs centering around cancer plasticity and hallmarks, and discusses these facts in light of therapeutics and biomarker development.
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Affiliation(s)
- Ishita Tandon
- Cancer & Translational Research Lab, Dr DY Patil Biotechnology & Bioinformatics Institute, Dr DY Patil Vidyapeeth, Pune, Maharashtra 411033, India
| | - Roshni Pal
- Cancer & Translational Research Lab, Dr DY Patil Biotechnology & Bioinformatics Institute, Dr DY Patil Vidyapeeth, Pune, Maharashtra 411033, India
| | - Jayanta K Pal
- Cancer & Translational Research Lab, Dr DY Patil Biotechnology & Bioinformatics Institute, Dr DY Patil Vidyapeeth, Pune, Maharashtra 411033, India
| | - Nilesh K Sharma
- Cancer & Translational Research Lab, Dr DY Patil Biotechnology & Bioinformatics Institute, Dr DY Patil Vidyapeeth, Pune, Maharashtra 411033, India
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45
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Lauer S, Gresham D. An evolving view of copy number variants. Curr Genet 2019; 65:1287-1295. [PMID: 31076843 DOI: 10.1007/s00294-019-00980-0] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Revised: 04/17/2019] [Accepted: 04/20/2019] [Indexed: 01/08/2023]
Abstract
Copy number variants (CNVs) are regions of the genome that vary in integer copy number. CNVs, which comprise both amplifications and deletions of DNA sequence, have been identified across all domains of life, from bacteria and archaea to plants and animals. CNVs are an important source of genetic diversity, and can drive rapid adaptive evolution and progression of heritable and somatic human diseases, such as cancer. However, despite their evolutionary importance and clinical relevance, CNVs remain understudied compared to single-nucleotide variants (SNVs). This is a consequence of the inherent difficulties in detecting CNVs at low-to-intermediate frequencies in heterogeneous populations of cells. Here, we discuss molecular methods used to detect CNVs, the limitations associated with using these techniques, and the application of new and emerging technologies that present solutions to these challenges. The goal of this short review and perspective is to highlight aspects of CNV biology that are understudied and define avenues for further research that address specific gaps in our knowledge of these complex alleles. We describe our recently developed method for CNV detection in which a fluorescent gene functions as a single-cell CNV reporter and present key findings from our evolution experiments in Saccharomyces cerevisiae. Using a CNV reporter, we found that CNVs are generated at a high rate and undergo selection with predictable dynamics across independently evolving replicate populations. Many CNVs appear to be generated through DNA replication-based processes that are mediated by the presence of short, interrupted, inverted-repeat sequences. Our results have important implications for the role of CNVs in evolutionary processes and the molecular mechanisms that underlie CNV formation. We discuss the possible extension of our method to other applications, including tracking the dynamics of CNVs in models of human tumors.
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Affiliation(s)
- Stephanie Lauer
- Institute for Systems Genetics, New York University Langone Health, New York, NY, USA
| | - David Gresham
- Center for Genomics and System Biology, Department of Biology, New York University, New York, NY, USA.
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46
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Lauer S, Avecilla G, Spealman P, Sethia G, Brandt N, Levy SF, Gresham D. Single-cell copy number variant detection reveals the dynamics and diversity of adaptation. PLoS Biol 2018; 16:e3000069. [PMID: 30562346 PMCID: PMC6298651 DOI: 10.1371/journal.pbio.3000069] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2018] [Accepted: 11/14/2018] [Indexed: 12/13/2022] Open
Abstract
Copy number variants (CNVs) are a pervasive source of genetic variation and evolutionary potential, but the dynamics and diversity of CNVs within evolving populations remain unclear. Long-term evolution experiments in chemostats provide an ideal system for studying the molecular processes underlying CNV formation and the temporal dynamics with which they are generated, selected, and maintained. Here, we developed a fluorescent CNV reporter to detect de novo gene amplifications and deletions in individual cells. We used the CNV reporter in Saccharomyces cerevisiae to study CNV formation at the GAP1 locus, which encodes the general amino acid permease, in different nutrient-limited chemostat conditions. We find that under strong selection, GAP1 CNVs are repeatedly generated and selected during the early stages of adaptive evolution, resulting in predictable dynamics. Molecular characterization of CNV-containing lineages shows that the CNV reporter detects different classes of CNVs, including aneuploidies, nonreciprocal translocations, tandem duplications, and complex CNVs. Despite GAP1's proximity to repeat sequences that facilitate intrachromosomal recombination, breakpoint analysis revealed that short inverted repeat sequences mediate formation of at least 50% of GAP1 CNVs. Inverted repeat sequences are also found at breakpoints at the DUR3 locus, where CNVs are selected in urea-limited chemostats. Analysis of 28 CNV breakpoints indicates that inverted repeats are typically 8 nucleotides in length and separated by 40 bases. The features of these CNVs are consistent with origin-dependent inverted-repeat amplification (ODIRA), suggesting that replication-based mechanisms of CNV formation may be a common source of gene amplification. We combined the CNV reporter with barcode lineage tracking and found that 102-104 independent CNV-containing lineages initially compete within populations, resulting in extreme clonal interference. However, only a small number (18-21) of CNV lineages ever constitute more than 1% of the CNV subpopulation, and as selection progresses, the diversity of CNV lineages declines. Our study introduces a novel means of studying CNVs in heterogeneous cell populations and provides insight into their dynamics, diversity, and formation mechanisms in the context of adaptive evolution.
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Affiliation(s)
- Stephanie Lauer
- Center for Genomics and Systems Biology, Department of Biology, New York University, New York, New York, United States of America
- Department of Biology, New York University, New York, New York, United States of America
| | - Grace Avecilla
- Center for Genomics and Systems Biology, Department of Biology, New York University, New York, New York, United States of America
- Department of Biology, New York University, New York, New York, United States of America
| | - Pieter Spealman
- Center for Genomics and Systems Biology, Department of Biology, New York University, New York, New York, United States of America
- Department of Biology, New York University, New York, New York, United States of America
| | - Gunjan Sethia
- Center for Genomics and Systems Biology, Department of Biology, New York University, New York, New York, United States of America
- Department of Biology, New York University, New York, New York, United States of America
| | - Nathan Brandt
- Center for Genomics and Systems Biology, Department of Biology, New York University, New York, New York, United States of America
- Department of Biology, New York University, New York, New York, United States of America
| | - Sasha F. Levy
- Joint Initiative for Metrology in Biology, National Institute of Standards and Technology, Stanford University, Stanford, California, United States of America
| | - David Gresham
- Center for Genomics and Systems Biology, Department of Biology, New York University, New York, New York, United States of America
- Department of Biology, New York University, New York, New York, United States of America
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