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Trajkovski M, Pastore A, Plavec J. Dimeric structures of DNA ATTTC repeats promoted by divalent cations. Nucleic Acids Res 2024; 52:1591-1601. [PMID: 38296828 PMCID: PMC10899783 DOI: 10.1093/nar/gkae052] [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: 10/26/2023] [Revised: 01/10/2024] [Accepted: 01/16/2024] [Indexed: 02/02/2024] Open
Abstract
Structural studies of repetitive DNA sequences may provide insights why and how certain repeat instabilities in their number and nucleotide sequence are managed or even required for normal cell physiology, while genomic variability associated with repeat expansions may also be disease-causing. The pentanucleotide ATTTC repeats occur in hundreds of genes important for various cellular processes, while their insertion and expansion in noncoding regions are associated with neurodegeneration, particularly with subtypes of spinocerebellar ataxia and familial adult myoclonic epilepsy. We describe a new striking domain-swapped DNA-DNA interaction triggered by the addition of divalent cations, including Mg2+ and Ca2+. The results of NMR characterization of d(ATTTC)3 in solution show that the oligonucleotide folds into a novel 3D architecture with two central C:C+ base pairs sandwiched between a couple of T:T base pairs. This structural element, referred to here as the TCCTzip, is characterized by intercalative hydrogen-bonding, while the nucleobase moieties are poorly stacked. The 5'- and 3'-ends of TCCTzip motif are connected by stem-loop segments characterized by A:T base pairs and stacking interactions. Insights embodied in the non-canonical DNA structure are expected to advance our understanding of why only certain pyrimidine-rich DNA repeats appear to be pathogenic, while others can occur in the human genome without any harmful consequences.
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Affiliation(s)
- Marko Trajkovski
- Slovenian NMR Centre, National Institute of Chemistry, 1000 Ljubljana, Slovenia
| | - Annalisa Pastore
- King's College London, the Maurice Wohl Clinical Neuroscience Institute, London, UK
| | - Janez Plavec
- Slovenian NMR Centre, National Institute of Chemistry, 1000 Ljubljana, Slovenia
- Faculty of Chemistry and Chemical Technology, University of Ljubljana, 1000 Ljubljana, Slovenia
- EN-FIST, Center of Excellence, 1000 Ljubljana, Slovenia
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2
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Wu N, Wei L, Zhu Z, Liu Q, Li K, Mao F, Qiao J, Zhao X. Innovative insights into extrachromosomal circular DNAs in gynecologic tumors and reproduction. Protein Cell 2024; 15:6-20. [PMID: 37233789 PMCID: PMC10762679 DOI: 10.1093/procel/pwad032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2023] [Accepted: 05/03/2023] [Indexed: 05/27/2023] Open
Abstract
Originating but free from chromosomal DNA, extrachromosomal circular DNAs (eccDNAs) are organized in circular form and have long been found in unicellular and multicellular eukaryotes. Their biogenesis and function are poorly understood as they are characterized by sequence homology with linear DNA, for which few detection methods are available. Recent advances in high-throughput sequencing technologies have revealed that eccDNAs play crucial roles in tumor formation, evolution, and drug resistance as well as aging, genomic diversity, and other biological processes, bringing it back to the research hotspot. Several mechanisms of eccDNA formation have been proposed, including the breakage-fusion-bridge (BFB) and translocation-deletion-amplification models. Gynecologic tumors and disorders of embryonic and fetal development are major threats to human reproductive health. The roles of eccDNAs in these pathological processes have been partially elucidated since the first discovery of eccDNA in pig sperm and the double minutes in ovarian cancer ascites. The present review summarized the research history, biogenesis, and currently available detection and analytical methods for eccDNAs and clarified their functions in gynecologic tumors and reproduction. We also proposed the application of eccDNAs as drug targets and liquid biopsy markers for prenatal diagnosis and the early detection, prognosis, and treatment of gynecologic tumors. This review lays theoretical foundations for future investigations into the complex regulatory networks of eccDNAs in vital physiological and pathological processes.
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Affiliation(s)
- Ning Wu
- State Key Laboratory of Female Fertility Promotion, Center for Reproductive Medicine, Department of Obstetrics and Gynecology, Center for Reproductive Medicine, Peking University Third Hospital, Beijing 100191, China
- National Clinical Research Center for Obstetrics and Gynecology, Peking University Third Hospital, Beijing 100191, China
- Key Laboratory of Assisted Reproduction (Peking University), Ministry of Education, Beijing 100191, China
- Beijing Key Laboratory of Reproductive Endocrinology and Assisted Reproductive Technology, Beijing 100191, China
| | - Ling Wei
- Institute of Medical Innovation and Research, Peking University Third Hospital, Beijing 100191, China
- Cancer Center, Peking University Third Hospital, Beijing 100191, China
| | - Zhipeng Zhu
- Institute of Medical Innovation and Research, Peking University Third Hospital, Beijing 100191, China
- Cancer Center, Peking University Third Hospital, Beijing 100191, China
| | - Qiang Liu
- State Key Laboratory of Female Fertility Promotion, Center for Reproductive Medicine, Department of Obstetrics and Gynecology, Center for Reproductive Medicine, Peking University Third Hospital, Beijing 100191, China
- National Clinical Research Center for Obstetrics and Gynecology, Peking University Third Hospital, Beijing 100191, China
- Key Laboratory of Assisted Reproduction (Peking University), Ministry of Education, Beijing 100191, China
- Beijing Key Laboratory of Reproductive Endocrinology and Assisted Reproductive Technology, Beijing 100191, China
| | - Kailong Li
- Department of Biochemistry and Biophysics, Beijing Key Laboratory of Protein Posttranslational Modifications and Cell Function, School of Basic Medical Sciences, Peking University Health Science Center, Beijing 100191, China
| | - Fengbiao Mao
- Institute of Medical Innovation and Research, Peking University Third Hospital, Beijing 100191, China
- Cancer Center, Peking University Third Hospital, Beijing 100191, China
| | - Jie Qiao
- State Key Laboratory of Female Fertility Promotion, Center for Reproductive Medicine, Department of Obstetrics and Gynecology, Center for Reproductive Medicine, Peking University Third Hospital, Beijing 100191, China
- National Clinical Research Center for Obstetrics and Gynecology, Peking University Third Hospital, Beijing 100191, China
- Key Laboratory of Assisted Reproduction (Peking University), Ministry of Education, Beijing 100191, China
- Beijing Key Laboratory of Reproductive Endocrinology and Assisted Reproductive Technology, Beijing 100191, China
- Beijing Advanced Innovation Center for Genomics, Beijing 100191, China
- Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100191, China
| | - Xiaolu Zhao
- State Key Laboratory of Female Fertility Promotion, Center for Reproductive Medicine, Department of Obstetrics and Gynecology, Center for Reproductive Medicine, Peking University Third Hospital, Beijing 100191, China
- National Clinical Research Center for Obstetrics and Gynecology, Peking University Third Hospital, Beijing 100191, China
- Key Laboratory of Assisted Reproduction (Peking University), Ministry of Education, Beijing 100191, China
- Beijing Key Laboratory of Reproductive Endocrinology and Assisted Reproductive Technology, Beijing 100191, China
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3
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Zuo S, Yi Y, Wang C, Li X, Zhou M, Peng Q, Zhou J, Yang Y, He Q. Extrachromosomal Circular DNA (eccDNA): From Chaos to Function. Front Cell Dev Biol 2022; 9:792555. [PMID: 35083218 PMCID: PMC8785647 DOI: 10.3389/fcell.2021.792555] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2021] [Accepted: 12/16/2021] [Indexed: 11/15/2022] Open
Abstract
Extrachromosomal circular DNA (eccDNA) is a type of double-stranded circular DNA that is derived and free from chromosomes. It has a strong heterogeneity in sequence, length, and origin and has been identified in both normal and cancer cells. Although many studies suggested its potential roles in various physiological and pathological procedures including aging, telomere and rDNA maintenance, drug resistance, and tumorigenesis, the functional relevance of eccDNA remains to be elucidated. Recently, due to technological advancements, accumulated evidence highlighted that eccDNA plays an important role in cancers by regulating the expression of oncogenes, chromosome accessibility, genome replication, immune response, and cellular communications. Here, we review the features, biogenesis, physiological functions, potential functions in cancer, and research methods of eccDNAs with a focus on some open problems in the field and provide a perspective on how eccDNAs evolve specific functions out of the chaos in cells.
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Affiliation(s)
- Shanru Zuo
- Department of Pharmacy, The Third Xiangya Hospital, Central South University, Changsha, China.,The Key Laboratory of Model Animals and Stem Cell Biology in Hunan Province, School of Medicine, Hunan Normal University, Changsha, China
| | - Yihu Yi
- Department of Orthopaedics, Wuhan Union Hospital, Wuhan, China
| | - Chen Wang
- Department of Obstetrics and Gynecology, The Third Xiangya Hospital of Central South University, Changsha, China
| | - Xueguang Li
- The Key Laboratory of Model Animals and Stem Cell Biology in Hunan Province, School of Medicine, Hunan Normal University, Changsha, China
| | - Mingqing Zhou
- Zhongshan Hospital Affiliated to Sun Yat-Sen University, Zhongshan People's Hospital, Zhongshan, China
| | - Qiyao Peng
- Institute of Chinese Medicine, Hunan Academy of Traditional Chinese Medicine and Innovation Centre for Science and Technology, Hunan University of Chinese Medicine, Changsa, China.,Chongqing Key Laboratory for Pharmaceutical Metabolism Research, College of Pharmacy, College of Traditional Chinese Medicine, Chongqing Medical University, Chongqing, China
| | - Junhua Zhou
- The Key Laboratory of Model Animals and Stem Cell Biology in Hunan Province, School of Medicine, Hunan Normal University, Changsha, China
| | - Yide Yang
- The Key Laboratory of Model Animals and Stem Cell Biology in Hunan Province, School of Medicine, Hunan Normal University, Changsha, China
| | - Quanyuan He
- The Key Laboratory of Model Animals and Stem Cell Biology in Hunan Province, School of Medicine, Hunan Normal University, Changsha, China
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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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5
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Wang M, Chen X, Yu F, Ding H, Zhang Y, Wang K. Extrachromosomal Circular DNAs: Origin, formation and emerging function in Cancer. Int J Biol Sci 2021; 17:1010-1025. [PMID: 33867825 PMCID: PMC8040306 DOI: 10.7150/ijbs.54614] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2020] [Accepted: 02/05/2021] [Indexed: 02/06/2023] Open
Abstract
The majority of cellular DNAs in eukaryotes are organized into linear chromosomes. In addition to chromosome DNAs, genes also reside on extrachromosomal elements. The extrachromosomal DNAs are commonly found to be circular, and they are referred to as extrachromosomal circular DNAs (eccDNAs). Recent technological advances have enriched our knowledge of eccDNA biology. There is currently increasing concern about the connection between eccDNA and cancer. Gene amplification on eccDNAs is prevalent in cancer. Moreover, eccDNAs commonly harbor oncogenes or drug resistance genes, hence providing a growth or survival advantage to cancer cells. eccDNAs play an important role in tumor heterogeneity and evolution, facilitating tumor adaptation to challenging circumstances. In addition, eccDNAs have recently been identified as cell-free DNAs in circulating system. The altered level of eccDNAs is observed in cancer patients relative to healthy controls. Particularly, eccDNAs are associated with cancer progression and poor outcomes. Thus, eccDNAs could be useful as novel biomarkers for the diagnosis and prognosis of cancer. In this review, we summarize current knowledge regarding the formation, characteristics and biological importance of eccDNAs, with a focus on the molecular mechanisms associated with their roles in cancer progression. We also discuss their potential applications in the detection and treatment of cancer. A better understanding of the functional role of eccDNAs in cancer would facilitate the comprehensive analysis of molecular mechanisms involved in cancer pathogenesis.
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Affiliation(s)
- Man Wang
- Institute for Translational Medicine, The Affiliated Hospital of Qingdao University, College of Medicine, Qingdao University, Qingdao 266021, China
| | - Xinzhe Chen
- Institute for Translational Medicine, The Affiliated Hospital of Qingdao University, College of Medicine, Qingdao University, Qingdao 266021, China
| | - Fei Yu
- Institute for Translational Medicine, The Affiliated Hospital of Qingdao University, College of Medicine, Qingdao University, Qingdao 266021, China
| | - Han Ding
- Institute for Translational Medicine, The Affiliated Hospital of Qingdao University, College of Medicine, Qingdao University, Qingdao 266021, China
| | - Yuan Zhang
- Institute for Translational Medicine, The Affiliated Hospital of Qingdao University, College of Medicine, Qingdao University, Qingdao 266021, China
| | - Kun Wang
- Institute for Translational Medicine, The Affiliated Hospital of Qingdao University, College of Medicine, Qingdao University, Qingdao 266021, China
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6
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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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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:ijms21072477. [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] [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
- Correspondence:
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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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Pal S, Postnikoff SD, Chavez M, Tyler JK. Impaired cohesion and homologous recombination during replicative aging in budding yeast. SCIENCE ADVANCES 2018; 4:eaaq0236. [PMID: 29441364 PMCID: PMC5810620 DOI: 10.1126/sciadv.aaq0236] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/21/2017] [Accepted: 01/09/2018] [Indexed: 06/08/2023]
Abstract
The causal relationship between genomic instability and replicative aging is unclear. We reveal here that genomic instability at the budding yeast ribosomal DNA (rDNA) locus increases during aging, potentially due to the reduced cohesion that we uncovered during aging caused by the reduced abundance of multiple cohesin subunits, promoting increased global chromosomal instability. In agreement, cohesion is lost during aging at other chromosomal locations in addition to the rDNA, including centromeres. The genomic instability in old cells is exacerbated by a defect in DNA double-strand break (DSB) repair that we uncovered in old yeast. This was due to limiting levels of key homologous recombination proteins because overexpression of Rad51 or Mre11 reduced the accumulation of DSBs and largely restored DSB repair in old cells. We propose that increased rDNA instability and the reduced DSB repair capacity of old cells contribute to the progressive accumulation of global chromosomal DNA breaks, where exceeding a threshold of genomic DNA damage ends the replicative life span.
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Affiliation(s)
- Sangita Pal
- Department of Pathology and Laboratory Medicine, Weill Cornell Medicine, New York, NY 10065, USA
- Department of Epigenetics and Molecular Carcinogenesis, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
- Genes and Development Graduate Program, The University of Texas MD Anderson Cancer Center, UTHealth Graduate School of Biomedical Sciences, Houston, TX 77030, USA
| | - Spike D. Postnikoff
- Department of Pathology and Laboratory Medicine, Weill Cornell Medicine, New York, NY 10065, USA
| | - Myrriah Chavez
- Department of Epigenetics and Molecular Carcinogenesis, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Jessica K. Tyler
- Department of Pathology and Laboratory Medicine, Weill Cornell Medicine, New York, NY 10065, USA
- Department of Epigenetics and Molecular Carcinogenesis, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
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Zhu J, Zhang F, Du M, Zhang P, Fu S, Wang L. Molecular characterization of cell-free eccDNAs in human plasma. Sci Rep 2017; 7:10968. [PMID: 28887493 PMCID: PMC5591271 DOI: 10.1038/s41598-017-11368-w] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2017] [Accepted: 08/23/2017] [Indexed: 12/18/2022] Open
Abstract
Extrachromosomal circular DNAs (eccDNAs) have been reported in most eukaryotes. However, little is known about the cell-free eccDNA profiles in circulating system such as blood. To characterize plasma cell-free eccDNAs, we performed sequencing analysis in 26 libraries from three blood donors and negative controls. We identified thousands of unique plasma eccDNAs in the three subjects. We observed proportional eccDNA increase with initial DNA input. The detected eccDNAs were also associated with circular DNA enrichment efficiency. Increasing the sequencing depth in an additional sample identified many more eccDNAs with highly heterogenous molecular structure. Size distribution of eccDNAs varied significantly from 31 bp to 19,989 bp. We found significantly higher GC content in smaller eccDNAs (<500 bp) than the larger ones (>500 bp) (p < 0.01). We also found an enrichment of eccDNAs at exons and 3′UTR (enrichment folds from 1.36 to 3.1) as well as the DNase hypersensitive sites (1.58–2.42 fold), H3K4Me1 (1.23–1.42 fold) and H3K27Ac (1.33–1.62 fold) marks. Junction sequence analysis suggested fundamental role of nonhomologous end joining mechanism during eccDNA formation. Further characterization of the extracellular eccDNAs in peripheral blood will facilitate understanding of their molecular mechanisms and potential clinical utilities.
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Affiliation(s)
- Jing Zhu
- Laboratory of Medical Genetics, Harbin Medical University, Harbin, Heilongjiang, 150081, China.,Department of Pathology and MCW Cancer Center, Medical College of Wisconsin, Milwaukee, WI, 53226, USA
| | - Fan Zhang
- School of Computer Science and Technology, Harbin Institute of Technology, Harbin, Heilongjiang, 150001, China
| | - Meijun Du
- Department of Pathology and MCW Cancer Center, Medical College of Wisconsin, Milwaukee, WI, 53226, USA
| | - Peng Zhang
- Department of Pathology and MCW Cancer Center, Medical College of Wisconsin, Milwaukee, WI, 53226, USA
| | - Songbin Fu
- Laboratory of Medical Genetics, Harbin Medical University, Harbin, Heilongjiang, 150081, China
| | - Liang Wang
- Department of Pathology and MCW Cancer Center, Medical College of Wisconsin, Milwaukee, WI, 53226, USA.
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Qiu GH. Protection of the genome and central protein-coding sequences by non-coding DNA against DNA damage from radiation. MUTATION RESEARCH-REVIEWS IN MUTATION RESEARCH 2015; 764:108-17. [DOI: 10.1016/j.mrrev.2015.04.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Revised: 03/11/2015] [Accepted: 04/22/2015] [Indexed: 01/08/2023]
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12
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How a replication origin and matrix attachment region accelerate gene amplification under replication stress in mammalian cells. PLoS One 2014; 9:e103439. [PMID: 25061979 PMCID: PMC4111587 DOI: 10.1371/journal.pone.0103439] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Accepted: 07/02/2014] [Indexed: 11/19/2022] Open
Abstract
The gene amplification plays a critical role in the malignant transformation of mammalian cells. The most widespread method for amplifying a target gene in cell culture is the use of methotrexate (Mtx) treatment to amplify dihydrofolate reductase (Dhfr). Whereas, we found that a plasmid bearing both a mammalian origin of replication (initiation region; IR) and a matrix attachment region (MAR) was spontaneously amplified in mammalian cells. In this study, we attempted to uncover the underlying mechanism by which the IR/MAR sequence might accelerate Mtx induced Dhfr amplification. The plasmid containing the IR/MAR was extrachromosomally amplified, and then integrated at multiple chromosomal locations within individual cells, increasing the likelihood that the plasmid might be inserted into a chromosomal environment that permits high expression and further amplification. Efficient amplification of this plasmid alleviated the genotoxicity of Mtx. Clone-based cytogenetic and sequence analysis revealed that the plasmid was amplified in a chromosomal context by breakage-fusion-bridge cycles operating either at the plasmid repeat or at the flanking fragile site activated by Mtx. This mechanism explains how a circular molecule bearing IR/MAR sequences of chromosomal origin might be amplified under replication stress, and also provides insight into gene amplification in human cancer.
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Galeote V, Bigey F, Beyne E, Novo M, Legras JL, Casaregola S, Dequin S. Amplification of a Zygosaccharomyces bailii DNA segment in wine yeast genomes by extrachromosomal circular DNA formation. PLoS One 2011; 6:e17872. [PMID: 21423766 PMCID: PMC3053389 DOI: 10.1371/journal.pone.0017872] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2010] [Accepted: 02/11/2011] [Indexed: 11/18/2022] Open
Abstract
We recently described the presence of large chromosomal segments resulting from independent horizontal gene transfer (HGT) events in the genome of Saccharomyces cerevisiae strains, mostly of wine origin. We report here evidence for the amplification of one of these segments, a 17 kb DNA segment from Zygosaccharomyces bailii, in the genome of S. cerevisiae strains. The copy number, organization and location of this region differ considerably between strains, indicating that the insertions are independent and that they are post-HGT events. We identified eight different forms in 28 S. cerevisiae strains, mostly of wine origin, with up to four different copies in a single strain. The organization of these forms and the identification of an autonomously replicating sequence functional in S. cerevisiae, strongly suggest that an extrachromosomal circular DNA (eccDNA) molecule serves as an intermediate in the amplification of the Z. bailii region in yeast genomes. We found little or no sequence similarity at the breakpoint regions, suggesting that the insertions may be mediated by nonhomologous recombination. The diversity between these regions in S. cerevisiae represents roughly one third the divergence among the genomes of wine strains, which confirms the recent origin of this event, posterior to the start of wine strain expansion. This is the first report of a circle-based mechanism for the expansion of a DNA segment, mediated by nonhomologous recombination, in natural yeast populations.
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MESH Headings
- Base Sequence
- Blotting, Southern
- Chromosome Breakpoints
- Chromosomes, Fungal/genetics
- DNA, Circular/genetics
- DNA, Fungal/genetics
- Diploidy
- Electrophoresis, Gel, Pulsed-Field
- Evolution, Molecular
- Extrachromosomal Inheritance/genetics
- Gene Amplification/genetics
- Gene Dosage/genetics
- Genetic Variation
- Genome, Fungal/genetics
- Models, Genetic
- Molecular Sequence Data
- Mutagenesis, Insertional/genetics
- Saccharomyces cerevisiae/genetics
- Wine/microbiology
- Zygosaccharomyces/genetics
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Affiliation(s)
| | - Frédéric Bigey
- INRA, UMR1083 Sciences Pour l'Œnologie, Montpellier, France
| | | | - Maite Novo
- INRA, UMR1083 Sciences Pour l'Œnologie, Montpellier, France
| | | | - Serge Casaregola
- CIRM-Levures, INRA, UMR1319 Micalis, AgroParisTech, Thiverval-Grignon, France
| | - Sylvie Dequin
- INRA, UMR1083 Sciences Pour l'Œnologie, Montpellier, France
- * E-mail:
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