1
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Iracane E, Arias-Sardá C, Maufrais C, Ene IV, d’Enfert C, Buscaino A. Identification of an active RNAi pathway in Candida albicans. Proc Natl Acad Sci U S A 2024; 121:e2315926121. [PMID: 38625945 PMCID: PMC11047096 DOI: 10.1073/pnas.2315926121] [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: 10/06/2023] [Accepted: 03/08/2024] [Indexed: 04/18/2024] Open
Abstract
RNA interference (RNAi) is a fundamental regulatory pathway with a wide range of functions, including regulation of gene expression and maintenance of genome stability. Although RNAi is widespread in the fungal kingdom, well-known species, such as the model yeast Saccharomyces cerevisiae, have lost the RNAi pathway. Until now evidence has been lacking for a fully functional RNAi pathway in Candida albicans, a human fungal pathogen considered critically important by the World Health Organization. Here, we demonstrated that the widely used C. albicans reference strain (SC5314) contains an inactivating missense mutation in the gene encoding for the central RNAi component Argonaute. In contrast, most other C. albicans isolates contain a canonical Argonaute protein predicted to be functional and RNAi-active. Indeed, using high-throughput small and long RNA sequencing combined with seamless CRISPR/Cas9-based gene editing, we demonstrate that an active C. albicans RNAi machinery represses expression of subtelomeric gene families. Thus, an intact and functional RNAi pathway exists in C. albicans, highlighting the importance of using multiple reference strains when studying this dangerous pathogen.
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Affiliation(s)
- Elise Iracane
- Kent Fungal Group, School of Biosciences, Division of Natural Sciences, University of Kent, CanterburyCT2 7NZ, United Kingdom
| | - Cristina Arias-Sardá
- Kent Fungal Group, School of Biosciences, Division of Natural Sciences, University of Kent, CanterburyCT2 7NZ, United Kingdom
| | - Corinne Maufrais
- Institut Pasteur, Université Paris Cité, Bioinformatic Hub, ParisF-75015, France
| | - Iuliana V. Ene
- Institut Pasteur, Université Paris Cité, Fungal Heterogeneity Group, ParisF-75015, France
| | - Christophe d’Enfert
- Institut Pasteur, Université Paris Cité, Institut national de recherche pour l’agriculture, l’alimentation et l’environnement USC2019, Fungal Biology and Pathogenicity Unit, ParisF-75015, France
| | - Alessia Buscaino
- Kent Fungal Group, School of Biosciences, Division of Natural Sciences, University of Kent, CanterburyCT2 7NZ, United Kingdom
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2
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Gálvez-Galván A, Garrido-Ramos MA, Prieto P. Bread wheat satellitome: a complex scenario in a huge genome. PLANT MOLECULAR BIOLOGY 2024; 114:8. [PMID: 38291213 PMCID: PMC10827815 DOI: 10.1007/s11103-023-01404-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2023] [Accepted: 11/01/2023] [Indexed: 02/01/2024]
Abstract
In bread wheat (Triticum aestivum L.), chromosome associations during meiosis are extremely regulated and initiate at the telomeres and subtelomeres, which are enriched in satellite DNA (satDNA). We present the study and characterization of the bread wheat satellitome to shed light on the molecular organization of wheat subtelomeres. Our results revealed that the 2.53% of bread wheat genome is composed by satDNA and subtelomeres are particularly enriched in such DNA sequences. Thirty-four satellite DNA (21 for the first time in this work) have been identified, analyzed and cytogenetically validated. Many of the satDNAs were specifically found at particular subtelomeric chromosome regions revealing the asymmetry in subtelomere organisation among the wheat subgenomes, which might play a role in proper homologous recognition and pairing during meiosis. An integrated physical map of the wheat satellitome was also constructed. To the best of our knowledge, our results show that the combination of both cytogenetics and genome research allowed the first comprehensive analysis of the wheat satellitome, shedding light on the complex wheat genome organization, especially on the polymorphic nature of subtelomeres and their putative implication in chromosome recognition and pairing during meiosis.
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Affiliation(s)
- Ana Gálvez-Galván
- Plant Breeding Department, Institute for Sustainable Agriculture, Agencia Estatal Consejo Superior de Investigaciones Científicas (CSIC), Avda. Menéndez Pidal, Campus Alameda del Obispo S/N, 14004, Córdoba, Spain
| | - Manuel A Garrido-Ramos
- Departamento de Genética, Facultad de Ciencias, Universidad de Granada, Avda. Fuentenueva S/N, 18071, Granada, Spain.
| | - Pilar Prieto
- Plant Breeding Department, Institute for Sustainable Agriculture, Agencia Estatal Consejo Superior de Investigaciones Científicas (CSIC), Avda. Menéndez Pidal, Campus Alameda del Obispo S/N, 14004, Córdoba, Spain.
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3
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Serrano-León IM, Prieto P, Aguilar M. Telomere and subtelomere high polymorphism might contribute to the specificity of homologous recognition and pairing during meiosis in barley in the context of breeding. BMC Genomics 2023; 24:642. [PMID: 37884878 PMCID: PMC10601145 DOI: 10.1186/s12864-023-09738-y] [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: 07/26/2023] [Accepted: 10/12/2023] [Indexed: 10/28/2023] Open
Abstract
Barley (Hordeum vulgare) is one of the most popular cereal crops globally. Although it is a diploid species, (2n = 2x = 14) the study of its genome organization is necessary in the framework of plant breeding since barley is often used in crosses with other cereals like wheat to provide them with advantageous characters. We already have an extensive knowledge on different stages of the meiosis, the cell division to generate the gametes in species with sexual reproduction, such as the formation of the synaptonemal complex, recombination, and chromosome segregation. But meiosis really starts with the identification of homologous chromosomes and pairing initiation, and it is still unclear how chromosomes exactly choose a partner to appropriately pair for additional recombination and segregation. In this work we present an exhaustive molecular analysis of both telomeres and subtelomeres of barley chromosome arms 2H-L, 3H-L and 5H-L. As expected, the analysis of multiple features, including transposable elements, repeats, GC content, predicted CpG islands, recombination hotspots, G4 quadruplexes, genes and targeted sequence motifs for key DNA-binding proteins, revealed a high degree of variability both in telomeres and subtelomeres. The molecular basis for the specificity of homologous recognition and pairing occurring in the early chromosomal interactions at the start of meiosis in barley may be provided by these polymorphisms. A more relevant role of telomeres and most distal part of subtelomeres is suggested.
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Affiliation(s)
- I M Serrano-León
- Plant Breeding Department, Institute for Sustainable Agriculture, Agencia Estatal Consejo Superior de Investigaciones Científicas (CSIC), Avenida Menéndez Pidal S/N., Campus Alameda del Obispo, 14004, Córdoba, Spain
| | - P Prieto
- Plant Breeding Department, Institute for Sustainable Agriculture, Agencia Estatal Consejo Superior de Investigaciones Científicas (CSIC), Avenida Menéndez Pidal S/N., Campus Alameda del Obispo, 14004, Córdoba, Spain.
| | - M Aguilar
- Área de Fisiología Vegetal, Universidad de Córdoba, Campus de Rabanales, Edif. C4, 3ª Planta, Córdoba, Spain
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4
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Závodník M, Fajkus P, Franek M, Kopecký D, Garcia S, Dodsworth S, Orejuela A, Kilar A, Ptáček J, Mátl M, Hýsková A, Fajkus J, Peška V. Telomerase RNA gene paralogs in plants - the usual pathway to unusual telomeres. THE NEW PHYTOLOGIST 2023; 239:2353-2366. [PMID: 37391893 DOI: 10.1111/nph.19110] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Accepted: 06/06/2023] [Indexed: 07/02/2023]
Abstract
Telomerase, telomeric DNA and associated proteins together represent a complex, finely tuned and functionally conserved mechanism that ensures genome integrity by protecting and maintaining chromosome ends. Changes in its components can threaten an organism's viability. Nevertheless, molecular innovation in telomere maintenance has occurred multiple times during eukaryote evolution, giving rise to species/taxa with unusual telomeric DNA sequences, telomerase components or telomerase-independent telomere maintenance. The central component of telomere maintenance machinery is telomerase RNA (TR) as it templates telomere DNA synthesis, its mutation can change telomere DNA and disrupt its recognition by telomere proteins, thereby leading to collapse of their end-protective and telomerase recruitment functions. Using a combination of bioinformatic and experimental approaches, we examine a plausible scenario of evolutionary changes in TR underlying telomere transitions. We identified plants harbouring multiple TR paralogs whose template regions could support the synthesis of diverse telomeres. In our hypothesis, formation of unusual telomeres is associated with the occurrence of TR paralogs that can accumulate mutations, and through their functional redundancy, allow for the adaptive evolution of the other telomere components. Experimental analyses of telomeres in the examined plants demonstrate evolutionary telomere transitions corresponding to TR paralogs with diverse template regions.
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Affiliation(s)
- Michal Závodník
- Laboratory of Functional Genomics and Proteomics, NCBR, Faculty of Science, Masaryk University, Brno, CZ-61137, Czech Republic
- Mendel Centre for Plant Genomics and Proteomics, CEITEC Masaryk University, Brno, CZ-62500, Czech Republic
| | - Petr Fajkus
- Mendel Centre for Plant Genomics and Proteomics, CEITEC Masaryk University, Brno, CZ-62500, Czech Republic
- Department of Cell Biology and Radiobiology, Institute of Biophysics of the Czech Academy of Sciences, Brno, CZ-61265, Czech Republic
| | - Michal Franek
- Mendel Centre for Plant Genomics and Proteomics, CEITEC Masaryk University, Brno, CZ-62500, Czech Republic
| | - David Kopecký
- Centre of Plant Structural and Functional Genomics, Institute of Experimental Botany of the Czech Academy of Sciences, Olomouc, CZ-779 00, Czech Republic
| | - Sònia Garcia
- Institut Botànic de Barcelona (IBB-CSIC), Passeig del Migdia S/N, Barcelona, 08038, Catalonia, Spain
| | - Steven Dodsworth
- School of Biological Sciences, University of Portsmouth, King Henry Building, King Henry I St., Portsmouth, PO1 2DY, UK
| | - Andrés Orejuela
- Grupo de Investigación en Recursos Naturales Amazónicos - GRAM, Facultad de Ingenierías y Ciencias Básicas and Herbario Etnobotánico del Piedemonte Andino Amazónico (HEAA), Instituto Tecnológico del Putumayo - ITP, Mocoa, Putumayo, Colombia
| | - Agata Kilar
- Laboratory of Functional Genomics and Proteomics, NCBR, Faculty of Science, Masaryk University, Brno, CZ-61137, Czech Republic
- Mendel Centre for Plant Genomics and Proteomics, CEITEC Masaryk University, Brno, CZ-62500, Czech Republic
| | - Jiří Ptáček
- Potato Research Institute Havlíčkův Brod Ltd, Havlíčkův Brod, CZ-58001, Czech Republic
| | - Martin Mátl
- Department of Cell Biology and Radiobiology, Institute of Biophysics of the Czech Academy of Sciences, Brno, CZ-61265, Czech Republic
| | - Anna Hýsková
- Laboratory of Functional Genomics and Proteomics, NCBR, Faculty of Science, Masaryk University, Brno, CZ-61137, Czech Republic
| | - Jiří Fajkus
- Laboratory of Functional Genomics and Proteomics, NCBR, Faculty of Science, Masaryk University, Brno, CZ-61137, Czech Republic
- Mendel Centre for Plant Genomics and Proteomics, CEITEC Masaryk University, Brno, CZ-62500, Czech Republic
- Department of Cell Biology and Radiobiology, Institute of Biophysics of the Czech Academy of Sciences, Brno, CZ-61265, Czech Republic
| | - Vratislav Peška
- Department of Cell Biology and Radiobiology, Institute of Biophysics of the Czech Academy of Sciences, Brno, CZ-61265, Czech Republic
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5
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Xiong Y, Zhang H, Zhou S, Ma L, Xiao W, Wu Y, Yuan YJ. Structural Variations and Adaptations of Synthetic Chromosome Ends Driven by SCRaMbLE in Haploid and Diploid Yeasts. ACS Synth Biol 2023; 12:689-699. [PMID: 36821394 DOI: 10.1021/acssynbio.2c00424] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
Abstract
Variations and adaptations of chromosome ends play an important role in eukaryotic karyotype evolution. Traditional experimental studies of the adaptations of chromosome ends mainly rely on the strategy of introducing defects; thus, the adaptation methods of survivors may vary depending on the initial defects. Here, using the SCRaMbLE strategy, we obtained a library of haploid and diploid synthetic strains with variations in chromosome ends. Analysis of the SCRaMbLEd survivors revealed four routes of adaptation: homologous recombination between nonhomologous chromosome arms (haploids) or homologous chromosome arms (diploids), site-specific recombination between intra- or interchromosomal ends, circularization of chromosomes, and loss of whole chromosomes (diploids). We also found that circularization of synthetic chromosomes can be generated by SCRaMbLE. Our study of various adaptation routes of chromosome ends provides insight into eukaryotic karyotype evolution from the viewpoint of synthetic genomics.
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Affiliation(s)
- Yao Xiong
- Frontiers Science Center for Synthetic Biology (Ministry of Education), Tianjin University, Tianjin 300072, China.,Key Laboratory of Systems Bioengineering (Ministry of Education), School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
| | - Hui Zhang
- Frontiers Science Center for Synthetic Biology (Ministry of Education), Tianjin University, Tianjin 300072, China.,Key Laboratory of Systems Bioengineering (Ministry of Education), School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
| | - Sijie Zhou
- Frontiers Science Center for Synthetic Biology (Ministry of Education), Tianjin University, Tianjin 300072, China.,Key Laboratory of Systems Bioengineering (Ministry of Education), School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
| | - Lu Ma
- Frontiers Science Center for Synthetic Biology (Ministry of Education), Tianjin University, Tianjin 300072, China.,Key Laboratory of Systems Bioengineering (Ministry of Education), School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
| | - Wenhai Xiao
- Frontiers Science Center for Synthetic Biology (Ministry of Education), Tianjin University, Tianjin 300072, China.,Key Laboratory of Systems Bioengineering (Ministry of Education), School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
| | - Yi Wu
- Frontiers Science Center for Synthetic Biology (Ministry of Education), Tianjin University, Tianjin 300072, China.,Key Laboratory of Systems Bioengineering (Ministry of Education), School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
| | - Ying-Jin Yuan
- Frontiers Science Center for Synthetic Biology (Ministry of Education), Tianjin University, Tianjin 300072, China.,Key Laboratory of Systems Bioengineering (Ministry of Education), School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
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6
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Lysak MA. Celebrating Mendel, McClintock, and Darlington: On end-to-end chromosome fusions and nested chromosome fusions. THE PLANT CELL 2022; 34:2475-2491. [PMID: 35441689 PMCID: PMC9252491 DOI: 10.1093/plcell/koac116] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Accepted: 04/13/2022] [Indexed: 05/04/2023]
Abstract
The evolution of eukaryotic genomes is accompanied by fluctuations in chromosome number, reflecting cycles of chromosome number increase (polyploidy and centric fissions) and decrease (chromosome fusions). Although all chromosome fusions result from DNA recombination between two or more nonhomologous chromosomes, several mechanisms of descending dysploidy are exploited by eukaryotes to reduce their chromosome number. Genome sequencing and comparative genomics have accelerated the identification of inter-genome chromosome collinearity and gross chromosomal rearrangements and have shown that end-to-end chromosome fusions (EEFs) and nested chromosome fusions (NCFs) may have played a more important role in the evolution of eukaryotic karyotypes than previously thought. The present review aims to summarize the limited knowledge on the origin, frequency, and evolutionary implications of EEF and NCF events in eukaryotes and especially in land plants. The interactions between nonhomologous chromosomes in interphase nuclei and chromosome (mis)pairing during meiosis are examined for their potential importance in the origin of EEFs and NCFs. The remaining open questions that need to be addressed are discussed.
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Affiliation(s)
- Martin A Lysak
- CEITEC—Central European Institute of Technology, Masaryk University, Brno, CZ-625 00, Czech Republic
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7
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Boštjančić LL, Bonassin L, Anušić L, Lovrenčić L, Besendorfer V, Maguire I, Grandjean F, Austin CM, Greve C, Hamadou AB, Mlinarec J. The Pontastacus leptodactylus (Astacidae) Repeatome Provides Insight Into Genome Evolution and Reveals Remarkable Diversity of Satellite DNA. Front Genet 2021; 11:611745. [PMID: 33552130 PMCID: PMC7859515 DOI: 10.3389/fgene.2020.611745] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Accepted: 12/21/2020] [Indexed: 12/14/2022] Open
Abstract
Pontastacus leptodactylus is a native European crayfish species found in both freshwater and brackish environments. It has commercial importance for fisheries and aquaculture industries. Up till now, most studies concerning P. leptodactylus have focused onto gaining knowledge about its phylogeny and population genetics. However, little is known about the chromosomal evolution and genome organization of this species. Therefore, we performed clustering analysis of a low coverage genomic dataset to identify and characterize repetitive DNA in the P. leptodactylus genome. In addition, the karyogram of P. leptodactylus (2n = 180) is presented here for the first time consisting of 75 metacentric, 14 submetacentric, and a submetacentric/metacentric heteromorphic chromosome pair. We determined the genome size to be at ~18.7 gigabase pairs. Repetitive DNA represents about 54.85% of the genome. Satellite DNA repeats are the most abundant type of repetitive DNA, making up to ~28% of the total amount of repetitive elements, followed by the Ty3/Gypsy retroelements (~15%). Our study established a surprisingly high diversity of satellite repeats in P. leptodactylus. The genome of P. leptodactylus is by far the most satellite-rich genome discovered to date with 258 satellite families described. Of the five mapped satellite DNA families on chromosomes, PlSAT3-411 co-localizes with the AT-rich DAPI positive probable (peri)centromeric heterochromatin on all chromosomes, while PlSAT14-79 co-localizes with the AT-rich DAPI positive (peri)centromeric heterochromatin on one chromosome and is also located subterminally and intercalary on some chromosomes. PlSAT1-21 is located intercalary in the vicinity of the (peri)centromeric heterochromatin on some chromosomes, while PlSAT6-70 and PlSAT7-134 are located intercalary on some P. leptodactylus chromosomes. The FISH results reveal amplification of interstitial telomeric repeats (ITRs) in P. leptodactylus. The prevalence of repetitive elements, especially the satellite DNA repeats, may have provided a driving force for the evolution of the P. leptodactylus genome.
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Affiliation(s)
| | - Lena Bonassin
- Division of Molecular Biology, Department of Biology, University of Zagreb, Zagreb, Croatia
| | - Lucija Anušić
- Division of Molecular Biology, Department of Biology, University of Zagreb, Zagreb, Croatia
| | - Leona Lovrenčić
- Division of Zoology, Department of Biology, University of Zagreb, Zagreb, Croatia
| | - Višnja Besendorfer
- Division of Molecular Biology, Department of Biology, University of Zagreb, Zagreb, Croatia
| | - Ivana Maguire
- Division of Zoology, Department of Biology, University of Zagreb, Zagreb, Croatia
| | - Frederic Grandjean
- Laboratoire Ecologie Biologie des Interactions-UMR CNRS 7267, University of Poitiers, Poitiers, France
| | - Christopher M. Austin
- Centre of Integrative Ecology, School of Life and Environmental Sciences Deakin University, Geelong, VIC, Australia
| | - Carola Greve
- LOEWE Centre for Translational Biodiversity Genomics (LOEWE-TBG), Frankfurt, Germany
| | - Alexander Ben Hamadou
- LOEWE Centre for Translational Biodiversity Genomics (LOEWE-TBG), Frankfurt, Germany
| | - Jelena Mlinarec
- Division of Molecular Biology, Department of Biology, University of Zagreb, Zagreb, Croatia
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8
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Aguilar M, Prieto P. Telomeres and Subtelomeres Dynamics in the Context of Early Chromosome Interactions During Meiosis and Their Implications in Plant Breeding. FRONTIERS IN PLANT SCIENCE 2021; 12:672489. [PMID: 34149773 PMCID: PMC8212018 DOI: 10.3389/fpls.2021.672489] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Accepted: 05/06/2021] [Indexed: 05/08/2023]
Abstract
Genomic architecture facilitates chromosome recognition, pairing, and recombination. Telomeres and subtelomeres play an important role at the beginning of meiosis in specific chromosome recognition and pairing, which are critical processes that allow chromosome recombination between homologs (equivalent chromosomes in the same genome) in later stages. In plant polyploids, these terminal regions are even more important in terms of homologous chromosome recognition, due to the presence of homoeologs (equivalent chromosomes from related genomes). Although telomeres interaction seems to assist homologous pairing and consequently, the progression of meiosis, other chromosome regions, such as subtelomeres, need to be considered, because the DNA sequence of telomeres is not chromosome-specific. In addition, recombination operates at subtelomeres and, as it happens in rye and wheat, homologous recognition and pairing is more often correlated with recombining regions than with crossover-poor regions. In a plant breeding context, the knowledge of how homologous chromosomes initiate pairing at the beginning of meiosis can contribute to chromosome manipulation in hybrids or interspecific genetic crosses. Thus, recombination in interspecific chromosome associations could be promoted with the aim of transferring desirable agronomic traits from related genetic donor species into crops. In this review, we summarize the importance of telomeres and subtelomeres on chromatin dynamics during early meiosis stages and their implications in recombination in a plant breeding framework.
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Affiliation(s)
- Miguel Aguilar
- Área de Fisiología Vegetal, Universidad de Córdoba, Córdoba, Spain
| | - Pilar Prieto
- Plant Breeding Department, Institute for Sustainable Agriculture, Agencia Estatal Consejo Superior de Investigaciones Científicas (CSIC), Córdoba, Spain
- *Correspondence: Pilar Prieto, ; orcid.org/0000-0002-8160-808X
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9
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Ahmad SF, Singchat W, Jehangir M, Suntronpong A, Panthum T, Malaivijitnond S, Srikulnath K. Dark Matter of Primate Genomes: Satellite DNA Repeats and Their Evolutionary Dynamics. Cells 2020; 9:E2714. [PMID: 33352976 PMCID: PMC7767330 DOI: 10.3390/cells9122714] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Revised: 12/15/2020] [Accepted: 12/16/2020] [Indexed: 12/12/2022] Open
Abstract
A substantial portion of the primate genome is composed of non-coding regions, so-called "dark matter", which includes an abundance of tandemly repeated sequences called satellite DNA. Collectively known as the satellitome, this genomic component offers exciting evolutionary insights into aspects of primate genome biology that raise new questions and challenge existing paradigms. A complete human reference genome was recently reported with telomere-to-telomere human X chromosome assembly that resolved hundreds of dark regions, encompassing a 3.1 Mb centromeric satellite array that had not been identified previously. With the recent exponential increase in the availability of primate genomes, and the development of modern genomic and bioinformatics tools, extensive growth in our knowledge concerning the structure, function, and evolution of satellite elements is expected. The current state of knowledge on this topic is summarized, highlighting various types of primate-specific satellite repeats to compare their proportions across diverse lineages. Inter- and intraspecific variation of satellite repeats in the primate genome are reviewed. The functional significance of these sequences is discussed by describing how the transcriptional activity of satellite repeats can affect gene expression during different cellular processes. Sex-linked satellites are outlined, together with their respective genomic organization. Mechanisms are proposed whereby satellite repeats might have emerged as novel sequences during different evolutionary phases. Finally, the main challenges that hinder the detection of satellite DNA are outlined and an overview of the latest methodologies to address technological limitations is presented.
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Affiliation(s)
- Syed Farhan Ahmad
- Laboratory of Animal Cytogenetics and Comparative Genomics (ACCG), Department of Genetics, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand; (S.F.A.); (W.S.); (M.J.); (A.S.); (T.P.)
- Special Research Unit for Wildlife Genomics (SRUWG), Department of Forest Biology, Faculty of Forestry, Kasetsart University, Bangkok 10900, Thailand
| | - Worapong Singchat
- Laboratory of Animal Cytogenetics and Comparative Genomics (ACCG), Department of Genetics, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand; (S.F.A.); (W.S.); (M.J.); (A.S.); (T.P.)
- Special Research Unit for Wildlife Genomics (SRUWG), Department of Forest Biology, Faculty of Forestry, Kasetsart University, Bangkok 10900, Thailand
| | - Maryam Jehangir
- Laboratory of Animal Cytogenetics and Comparative Genomics (ACCG), Department of Genetics, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand; (S.F.A.); (W.S.); (M.J.); (A.S.); (T.P.)
- Department of Structural and Functional Biology, Institute of Bioscience at Botucatu, São Paulo State University (UNESP), Botucatu, São Paulo 18618-689, Brazil
| | - Aorarat Suntronpong
- Laboratory of Animal Cytogenetics and Comparative Genomics (ACCG), Department of Genetics, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand; (S.F.A.); (W.S.); (M.J.); (A.S.); (T.P.)
- Special Research Unit for Wildlife Genomics (SRUWG), Department of Forest Biology, Faculty of Forestry, Kasetsart University, Bangkok 10900, Thailand
| | - Thitipong Panthum
- Laboratory of Animal Cytogenetics and Comparative Genomics (ACCG), Department of Genetics, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand; (S.F.A.); (W.S.); (M.J.); (A.S.); (T.P.)
- Special Research Unit for Wildlife Genomics (SRUWG), Department of Forest Biology, Faculty of Forestry, Kasetsart University, Bangkok 10900, Thailand
| | - Suchinda Malaivijitnond
- National Primate Research Center of Thailand, Chulalongkorn University, Saraburi 18110, Thailand;
- Department of Biology, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand
| | - Kornsorn Srikulnath
- Laboratory of Animal Cytogenetics and Comparative Genomics (ACCG), Department of Genetics, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand; (S.F.A.); (W.S.); (M.J.); (A.S.); (T.P.)
- Special Research Unit for Wildlife Genomics (SRUWG), Department of Forest Biology, Faculty of Forestry, Kasetsart University, Bangkok 10900, Thailand
- National Primate Research Center of Thailand, Chulalongkorn University, Saraburi 18110, Thailand;
- Center of Excellence on Agricultural Biotechnology (AG-BIO/PERDO-CHE), Bangkok 10900, Thailand
- Omics Center for Agriculture, Bioresources, Food and Health, Kasetsart University (OmiKU), Bangkok 10900, Thailand
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10
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Aguilar M, Prieto P. Sequence analysis of wheat subtelomeres reveals a high polymorphism among homoeologous chromosomes. THE PLANT GENOME 2020; 13:e20065. [PMID: 33029942 DOI: 10.1002/tpg2.20065] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Revised: 07/20/2020] [Accepted: 09/08/2020] [Indexed: 05/23/2023]
Abstract
Bread wheat, Triticum aestivum L., is one of the most important crops in the world. Understanding its genome organization (allohexaploid; AABBDD; 2n = 6x = 42) is essential for geneticists and plant breeders. Particularly, the knowledge of how homologous chromosomes (equivalent chromosomes from the same genome) specifically recognize each other to pair at the beginning of meiosis, the cellular process to generate gametes in sexually reproducing organisms, is fundamental for plant breeding and has a big influence on the fertility of wheat plants. Initial homologous chromosome interactions contribute to specific recognition and pairing between homologues at the onset of meiosis. Understanding the molecular basis of these critical processes can help to develop genetic tools in a breeding context to promote interspecific chromosome associations in hybrids or interspecific genetic crosses to facilitate the transfer of desirable agronomic traits from related species into a crop like wheat. The terminal regions of chromosomes, which include telomeres and subtelomeres, participate in chromosome recognition and pairing. We present a detailed molecular analysis of subtelomeres of wheat chromosome arms 1AS, 4AS, 7AS, 7BS and 7DS. Results showed a high polymorphism in the subtelomeric region among homoeologues (equivalent chromosomes from related genomes) for all the features analyzed, including genes, transposable elements, repeats, GC content, predicted CpG islands, recombination hotspots and targeted sequence motifs for relevant DNA-binding proteins. These polymorphisms might be the molecular basis for the specificity of homologous recognition and pairing in initial chromosome interactions at the beginning of meiosis in wheat.
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Affiliation(s)
- Miguel Aguilar
- Área de Fisiología Vegetal. Universidad de Córdoba. Campus de Rabanales, edif. C4, 3a planta, Córdoba, Spain
| | - Pilar Prieto
- Plant Breeding Department, Institute for Sustainable Agriculture, Agencia Estatal Consejo Superior de Investigaciones Científicas (CSIC), Alameda del Obispo s/n, Apartado 4084, Córdoba, 14080, Spain
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11
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Koroleva AG, Evtushenko EV, Vershinin AV, Zaytseva EP, Timoshkin OA, Kirilchik SV. Age Dynamics of Telomere Length in Endemic Baikal Planarians. Mol Biol 2020. [DOI: 10.1134/s002689332004007x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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12
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Morinha F, Magalhães P, Blanco G. Standard guidelines for the publication of telomere qPCR results in evolutionary ecology. Mol Ecol Resour 2020; 20. [PMID: 32133733 DOI: 10.1111/1755-0998.13152] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2019] [Revised: 02/25/2020] [Accepted: 02/27/2020] [Indexed: 12/14/2022]
Abstract
Telomere length has been used as a proxy of fitness, aging and lifespan in vertebrates. In the last decade, dozens of articles reporting on telomere dynamics in the fields of ecology and evolution have been published for a wide range of taxa. With this growing interest, it is necessary to ensure the accuracy and reproducibility of telomere length measurement techniques. Real-time quantitative PCR (qPCR) is routinely applied to measure relative telomere length. However, this technique is highly sensitive to several methodological variables and the optimization of qPCR telomere assays remains highly variable between studies. Therefore, standardized guidelines are required to enable the optimization of robust protocols, and to help in judging the validity of the presented results. This review provides an overview of preanalytical and analytical factors that can lead to qPCR inconsistencies and biases, including: (a) sample type, collection and storage; (b) DNA extraction, storage and quality; (c) qPCR primers, laboratory reagents, and assay conditions; and (d) data analysis. We propose a minimum level of information for publication of qPCR telomere assays in evolutionary ecology considering the methodological pitfalls and sources of error. This review highlights the complexity of the optimization and validation of qPCR for telomere measurement per se, demonstrating the importance of transparency and clarity of reporting methodological details required for reliable, reproducible and comparable qPCR telomere assays. We encourage efforts to implement standardized protocols that ensure the rigour and quality of telomere dynamics studies.
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Affiliation(s)
- Francisco Morinha
- Department of Evolutionary Ecology, National Museum of Natural Sciences (MNCN), Spanish National Research Council (CSIC), Madrid, Spain
| | - Paula Magalhães
- i3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal.,IBMC-Instituto de Biologia Molecular e Celular, Universidade do Porto, Porto, Portugal
| | - Guillermo Blanco
- Department of Evolutionary Ecology, National Museum of Natural Sciences (MNCN), Spanish National Research Council (CSIC), Madrid, Spain
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13
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14
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Towards the Mechanism of Yeast Telomere Dynamics. Trends Cell Biol 2019; 29:361-370. [PMID: 30765145 DOI: 10.1016/j.tcb.2019.01.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Revised: 01/04/2019] [Accepted: 01/11/2019] [Indexed: 12/31/2022]
Abstract
A mechanistic understanding of the yeast telomere requires an integrated understanding of telomere chromatin structure (telosomes), telomeric origins of replications, telomere length homeostasis, and telosome epigenetics. Recent molecular and genetic studies of the yeast telosomal components Rap1, Rif1, and Rif2, the Mre11 complex, and Tel1ATM promise to increase our insight into the coordination between these processes. Here, an intricate relationship is proposed between these multiple components that has resulted in increased appreciation of the multiple levels of telomere length control and their differentiation from double-strand repair. The mre11A470 motif (A470-A482) alleles have also opened new avenues to the exploration of telosome structure and function.
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15
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Mlinarec J, Skuhala A, Jurković A, Malenica N, McCann J, Weiss-Schneeweiss H, Bohanec B, Besendorfer V. The Repetitive DNA Composition in the Natural Pesticide Producer Tanacetum cinerariifolium: Interindividual Variation of Subtelomeric Tandem Repeats. FRONTIERS IN PLANT SCIENCE 2019; 10:613. [PMID: 31156676 PMCID: PMC6532368 DOI: 10.3389/fpls.2019.00613] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Accepted: 04/25/2019] [Indexed: 05/02/2023]
Abstract
Dalmatian pyrethrum (Tanacetum cinerariifolium (Trevir.) Sch. Bip.), a plant species endemic to the east Adriatic coast, is used worldwide for production of the organic insecticide, pyrethrin. Most studies concerning Dalmatian pyrethrum have focused on its morphological and biochemical traits relevant for breeding. However, little is known about the chromosomal evolution and genome organization of this species. Our study aims are to identify, classify, and characterize repetitive DNA in the T. cinerariifolium genome using clustering analysis of a low coverage genomic dataset. Repetitive DNA represents about 71.63% of the genome. T. cinerariifolium exhibits linked 5S and 35S rDNA configuration (L-type). FISH reveals amplification of interstitial telomeric repeats (ITRs) in T. cinerariifolium. Of the three newly identified satellite DNA families, TcSAT1 and TcSAT2 are located subterminally on most of T. cinerariifolium chromosomes, while TcSAT3 family is located intercalary within the longer arm of two chromosome pairs. FISH reveals high levels of polymorphism of the TcSAT1 and TcSAT2 sites by comparative screening of 28 individuals. TcSAT2 is more variable than TcSAT1 regarding the number and position of FISH signals. Altogether, our data highlights the dynamic nature of DNA sequences associated with subtelomeres in T. cinerariifolium and suggests that subtelomeres represent one of the most dynamic and rapidly evolving regions in eukaryotic genomes.
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Affiliation(s)
- Jelena Mlinarec
- Division of Molecular Biology, Department of Biology, Faculty of Science, Zagreb, Croatia
- *Correspondence: Jelena Mlinarec, orcid.org/0000-0002-2627-5374 Hanna Weiss-Schneeweiss, orcid.org/0000-0002-9530-6808
| | - Ana Skuhala
- Division of Molecular Biology, Department of Biology, Faculty of Science, Zagreb, Croatia
| | - Adela Jurković
- Division of Molecular Biology, Department of Biology, Faculty of Science, Zagreb, Croatia
| | - Nenad Malenica
- Division of Molecular Biology, Department of Biology, Faculty of Science, Zagreb, Croatia
| | - Jamie McCann
- Institute of Biotechnology, University of Natural Resources and Life Sciences, Vienna, Vienna, Austria
| | - Hanna Weiss-Schneeweiss
- Department of Botany and Biodiversity Research, University of Vienna, Vienna, Austria
- *Correspondence: Jelena Mlinarec, orcid.org/0000-0002-2627-5374 Hanna Weiss-Schneeweiss, orcid.org/0000-0002-9530-6808
| | | | - Višnja Besendorfer
- Division of Molecular Biology, Department of Biology, Faculty of Science, Zagreb, Croatia
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16
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Reichert S, Stier A. Does oxidative stress shorten telomeres in vivo? A review. Biol Lett 2018; 13:rsbl.2017.0463. [PMID: 29212750 DOI: 10.1098/rsbl.2017.0463] [Citation(s) in RCA: 212] [Impact Index Per Article: 35.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Accepted: 11/14/2017] [Indexed: 12/28/2022] Open
Abstract
The length of telomeres, the protective caps of chromosomes, is increasingly used as a biomarker of individual health state because it has been shown to predict chances of survival in a range of endothermic species including humans. Oxidative stress is presumed to be a major cause of telomere shortening, but most evidence to date comes from in vitro cultured cells. The importance of oxidative stress as a determinant of telomere shortening in vivo remains less clear and has recently been questioned. We, therefore, reviewed correlative and experimental studies investigating the links between oxidative stress and telomere shortening in vivo While correlative studies provide equivocal support for a connection between oxidative stress and telomere attrition (10 of 18 studies), most experimental studies published so far (seven of eight studies) partially or fully support this hypothesis. Yet, this link seems to be tissue-dependent in some cases, or restricted to particular categories of individual (e.g. sex-dependent) in other cases. More experimental studies, especially those decreasing antioxidant protection or increasing pro-oxidant generation, are required to further our understanding of the importance of oxidative stress in determining telomere length in vivo Studies comparing growing versus adult individuals, or proliferative versus non-proliferative tissues would provide particularly important insights.
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Affiliation(s)
- Sophie Reichert
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, UK.,Department of Animal and Plant Science, University of Sheffield, Sheffield, UK
| | - Antoine Stier
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, UK
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17
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Mercy G, Mozziconacci J, Scolari VF, Yang K, Zhao G, Thierry A, Luo Y, Mitchell LA, Shen M, Shen Y, Walker R, Zhang W, Wu Y, Xie ZX, Luo Z, Cai Y, Dai J, Yang H, Yuan YJ, Boeke JD, Bader JS, Muller H, Koszul R. 3D organization of synthetic and scrambled chromosomes. Science 2017; 355:355/6329/eaaf4597. [PMID: 28280150 DOI: 10.1126/science.aaf4597] [Citation(s) in RCA: 89] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Accepted: 02/01/2017] [Indexed: 11/02/2022]
Abstract
Although the design of the synthetic yeast genome Sc2.0 is highly conservative with respect to gene content, the deletion of several classes of repeated sequences and the introduction of thousands of designer changes may affect genome organization and potentially alter cellular functions. We report here the Hi-C-determined three-dimensional (3D) conformations of Sc2.0 chromosomes. The absence of repeats leads to a smoother contact pattern and more precisely tractable chromosome conformations, and the large-scale genomic organization is globally unaffected by the presence of synthetic chromosome(s). Two exceptions are synIII, which lacks the silent mating-type cassettes, and synXII, specifically when the ribosomal DNA is moved to another chromosome. We also exploit the contact maps to detect rearrangements induced in SCRaMbLE (synthetic chromosome rearrangement and modification by loxP-mediated evolution) strains.
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Affiliation(s)
- Guillaume Mercy
- Spatial Regulation of Genomes, Department of Genomes and Genetics, Institut Pasteur, Paris 75015, France.,UMR3525, Centre National de la Recherche Scientifique (CNRS), Paris 75015, France.,Sorbonne Universités, Université Pierre et Marie Curie (Université Paris 6), Paris 75005, France
| | - Julien Mozziconacci
- Laboratoire de Physique Théorique de la Matière Condensée, CNRS UMR7600, Université Pierre et Marie Curie (Université Paris 6), Sorbonne Universités, Paris, France
| | - Vittore F Scolari
- Spatial Regulation of Genomes, Department of Genomes and Genetics, Institut Pasteur, Paris 75015, France.,UMR3525, Centre National de la Recherche Scientifique (CNRS), Paris 75015, France
| | - Kun Yang
- Department of Biomedical Engineering and High-Throughput Biology Center, Whiting School of Engineering, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Guanghou Zhao
- Key Laboratory for Industrial Biocatalysis (Ministry of Education), Key Laboratory of Bioinformatics (Ministry of Education), Center for Synthetic and Systems Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Agnès Thierry
- Spatial Regulation of Genomes, Department of Genomes and Genetics, Institut Pasteur, Paris 75015, France.,UMR3525, Centre National de la Recherche Scientifique (CNRS), Paris 75015, France
| | - Yisha Luo
- School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3BF, UK
| | - Leslie A Mitchell
- Institute for Systems Genetics and Department of Biochemistry and Molecular Pharmacology, Langone Medical Center, New York University, New York, NY 10016, USA
| | - Michael Shen
- Institute for Systems Genetics and Department of Biochemistry and Molecular Pharmacology, Langone Medical Center, New York University, New York, NY 10016, USA
| | - Yue Shen
- BGI-Shenzhen, Shenzhen 518083, China.,BGI-Qingdao, Qingdao 266555, China.,School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3BF, UK
| | - Roy Walker
- School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3BF, UK
| | - Weimin Zhang
- Key Laboratory for Industrial Biocatalysis (Ministry of Education), Key Laboratory of Bioinformatics (Ministry of Education), Center for Synthetic and Systems Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Yi Wu
- Key Laboratory of Systems Bioengineering (Ministry of Education), SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
| | - Ze-Xiong Xie
- Key Laboratory of Systems Bioengineering (Ministry of Education), SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
| | - Zhouqing Luo
- Key Laboratory for Industrial Biocatalysis (Ministry of Education), Key Laboratory of Bioinformatics (Ministry of Education), Center for Synthetic and Systems Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Yizhi Cai
- School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3BF, UK
| | - Junbiao Dai
- Key Laboratory for Industrial Biocatalysis (Ministry of Education), Key Laboratory of Bioinformatics (Ministry of Education), Center for Synthetic and Systems Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Huanming Yang
- James D. Watson Institute of Genome Sciences, Hangzhou 310058, China.,BGI-Shenzhen, Shenzhen 518083, China
| | - Ying-Jin Yuan
- Key Laboratory of Systems Bioengineering (Ministry of Education), SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
| | - Jef D Boeke
- Institute for Systems Genetics and Department of Biochemistry and Molecular Pharmacology, Langone Medical Center, New York University, New York, NY 10016, USA
| | - Joel S Bader
- Department of Biomedical Engineering and High-Throughput Biology Center, Whiting School of Engineering, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Héloïse Muller
- Spatial Regulation of Genomes, Department of Genomes and Genetics, Institut Pasteur, Paris 75015, France. .,UMR3525, Centre National de la Recherche Scientifique (CNRS), Paris 75015, France
| | - Romain Koszul
- Spatial Regulation of Genomes, Department of Genomes and Genetics, Institut Pasteur, Paris 75015, France. .,UMR3525, Centre National de la Recherche Scientifique (CNRS), Paris 75015, France
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18
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Garrido-Ramos MA. Satellite DNA: An Evolving Topic. Genes (Basel) 2017; 8:genes8090230. [PMID: 28926993 PMCID: PMC5615363 DOI: 10.3390/genes8090230] [Citation(s) in RCA: 234] [Impact Index Per Article: 33.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Revised: 09/12/2017] [Accepted: 09/13/2017] [Indexed: 12/22/2022] Open
Abstract
Satellite DNA represents one of the most fascinating parts of the repetitive fraction of the eukaryotic genome. Since the discovery of highly repetitive tandem DNA in the 1960s, a lot of literature has extensively covered various topics related to the structure, organization, function, and evolution of such sequences. Today, with the advent of genomic tools, the study of satellite DNA has regained a great interest. Thus, Next-Generation Sequencing (NGS), together with high-throughput in silico analysis of the information contained in NGS reads, has revolutionized the analysis of the repetitive fraction of the eukaryotic genomes. The whole of the historical and current approaches to the topic gives us a broad view of the function and evolution of satellite DNA and its role in chromosomal evolution. Currently, we have extensive information on the molecular, chromosomal, biological, and population factors that affect the evolutionary fate of satellite DNA, knowledge that gives rise to a series of hypotheses that get on well with each other about the origin, spreading, and evolution of satellite DNA. In this paper, I review these hypotheses from a methodological, conceptual, and historical perspective and frame them in the context of chromosomal organization and evolution.
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Affiliation(s)
- Manuel A Garrido-Ramos
- Departamento de Genética, Facultad de Ciencias, Universidad de Granada, 18071 Granada, Spain.
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19
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Schrumpfová PP, Vychodilová I, Hapala J, Schořová Š, Dvořáček V, Fajkus J. Telomere binding protein TRB1 is associated with promoters of translation machinery genes in vivo. PLANT MOLECULAR BIOLOGY 2016; 90:189-206. [PMID: 26597966 DOI: 10.1007/s11103-015-0409-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Accepted: 11/16/2015] [Indexed: 05/24/2023]
Abstract
Recently we characterised TRB1, a protein from a single-myb-histone family, as a structural and functional component of telomeres in Arabidopsis thaliana. TRB proteins, besides their ability to bind specifically to telomeric DNA using their N-terminally positioned myb-like domain of the same type as in human shelterin proteins TRF1 or TRF2, also possess a histone-like domain which is involved in protein-protein interactions e.g., with POT1b. Here we set out to investigate the genome-wide localization pattern of TRB1 to reveal its preferential sites of binding to chromatin in vivo and its potential functional roles in the genome-wide context. Our results demonstrate that TRB1 is preferentially associated with promoter regions of genes involved in ribosome biogenesis, in addition to its roles at telomeres. This preference coincides with the frequent occurrence of telobox motifs in the upstream regions of genes in this category, but it is not restricted to the presence of a telobox. We conclude that TRB1 shows a specific genome-wide distribution pattern which suggests its role in regulation of genes involved in biogenesis of the translational machinery, in addition to its preferential telomeric localization.
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Affiliation(s)
- Petra Procházková Schrumpfová
- Mendel Centre for Plant Genomics and Proteomics, CEITEC - Central European Institute of Technology, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic
- Laboratory of Functional Genomics and Proteomics, National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic
| | - Ivona Vychodilová
- Mendel Centre for Plant Genomics and Proteomics, CEITEC - Central European Institute of Technology, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic
- Laboratory of Functional Genomics and Proteomics, National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic
| | - Jan Hapala
- Mendel Centre for Plant Genomics and Proteomics, CEITEC - Central European Institute of Technology, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic
- Laboratory of Functional Genomics and Proteomics, National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic
| | - Šárka Schořová
- Mendel Centre for Plant Genomics and Proteomics, CEITEC - Central European Institute of Technology, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic
- Laboratory of Functional Genomics and Proteomics, National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic
| | - Vojtěch Dvořáček
- Mendel Centre for Plant Genomics and Proteomics, CEITEC - Central European Institute of Technology, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic
- Institute of Biophysics, Academy of Sciences of the Czech Republic, v.v.i., Královopolská 135, 61265, Brno, Czech Republic
| | - Jiří Fajkus
- Mendel Centre for Plant Genomics and Proteomics, CEITEC - Central European Institute of Technology, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic.
- Laboratory of Functional Genomics and Proteomics, National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic.
- Institute of Biophysics, Academy of Sciences of the Czech Republic, v.v.i., Královopolská 135, 61265, Brno, Czech Republic.
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20
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Garrido-Ramos MA. Satellite DNA in Plants: More than Just Rubbish. Cytogenet Genome Res 2015; 146:153-170. [PMID: 26202574 DOI: 10.1159/000437008] [Citation(s) in RCA: 111] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/20/2015] [Indexed: 11/19/2022] Open
Abstract
For decades, satellite DNAs have been the hidden part of genomes. Initially considered as junk DNA, there is currently an increasing appreciation of the functional significance of satellite DNA repeats and of their sequences. Satellite DNA families accumulate in the heterochromatin in different parts of the eukaryotic chromosomes, mainly in pericentromeric and subtelomeric regions, but they also span the functional centromere. Tandem repeat sequences may spread from subtelomeric to interstitial loci, leading to the formation of chromosome-specific loci or to the accumulation in equilocal sites in different chromosomes. They also appear as the main components of the heterochromatin in the sex-specific region of sex chromosomes. Satellite DNA, required for chromosome organization, also plays a role in pairing and segregation. Some satellite repeats are transcribed and can participate in the formation and maintenance of heterochromatin structure and in the modulation of gene expression. In addition to the identification of the different satellite DNA families, their characteristics and location, we are interested in determining their impact on the genomes, by identifying the mechanisms leading to their appearance and amplification as well as in understanding how they change over time, the factors affecting these changes, and the influence exerted by the evolutionary history of the organisms. On the other hand, satellite DNA sequences are rapidly evolving sequences that may cause reproductive barriers between organisms and promote speciation. The accumulation of experimental data collected in recent years and the emergence of new approaches based on next-generation sequencing and high-throughput genome analysis are opening new perspectives that are changing our understanding of satellite DNA. This review examines recent data to provide a timely update on the overall information gathered about this part of the genome, focusing on the advances in the knowledge of its origin, its evolution, and its potential functional roles.
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21
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Mohammed AJ, Imad HH, Muhanned AK. Detection of new variant Off-ladder at the D12S391, D19S433 and D1S1656 loci and tri-allelic pattern at the D16S539 locus in a 21 locus autosomal short tandem repeat database of 400 Iraqi Individuals. ACTA ACUST UNITED AC 2015. [DOI: 10.5897/ajb2014.14103] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
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22
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Calderón MDC, Rey MD, Cabrera A, Prieto P. The subtelomeric region is important for chromosome recognition and pairing during meiosis. Sci Rep 2014; 4:6488. [PMID: 25270583 PMCID: PMC4180820 DOI: 10.1038/srep06488] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Accepted: 09/10/2014] [Indexed: 12/26/2022] Open
Abstract
The process of meiosis results in the formation of haploid daughter cells, each of which inherit a half of the diploid parental cells' genetic material. The ordered association of homologues (identical chromosomes) is a critical prerequisite for a successful outcome of meiosis. Homologue recognition and pairing are initiated at the chromosome ends, which comprise the telomere dominated by generic repetitive sequences, and the adjacent subtelomeric region, which harbours chromosome-specific sequences. In many organisms telomeres are responsible for bringing the ends of the chromosomes close together during early meiosis, but little is known regarding the role of the subtelomeric region sequence during meiosis. Here, the observation of homologue pairing between a pair of Hordeum chilense chromosomes lacking the subtelomeric region on one chromosome arm indicates that the subtelomeric region is important for the process of homologous chromosome recognition and pairing.
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Affiliation(s)
- María del Carmen Calderón
- Plant Breeding Department, Institute for Sustainable Agriculture, Agencia Estatal Consejo Superior de Investigaciones Científicas (CSIC), Apartado 4084, E-14080 Córdoba, Spain
| | - María-Dolores Rey
- Plant Breeding Department, Institute for Sustainable Agriculture, Agencia Estatal Consejo Superior de Investigaciones Científicas (CSIC), Apartado 4084, E-14080 Córdoba, Spain
| | - Adoración Cabrera
- Department of Genetics, ETSIAM, University of Córdoba, Campus de Excelencia Internacional Agroalimentario, CeiA3, 14071 Córdoba, Spain
| | - Pilar Prieto
- Plant Breeding Department, Institute for Sustainable Agriculture, Agencia Estatal Consejo Superior de Investigaciones Científicas (CSIC), Apartado 4084, E-14080 Córdoba, Spain
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23
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Voillemot M, Hine K, Zahn S, Criscuolo F, Gustafsson L, Doligez B, Bize P. Effects of brood size manipulation and common origin on phenotype and telomere length in nestling collared flycatchers. BMC Ecol 2012; 12:17. [PMID: 22901085 PMCID: PMC3547695 DOI: 10.1186/1472-6785-12-17] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2012] [Accepted: 08/13/2012] [Indexed: 12/13/2022] Open
Abstract
Background Evidence is accumulating that telomere length is a good predictor of life expectancy, especially early in life, thus calling for determining the factors that affect telomere length at this stage. Here, we investigated the relative influence of early growth conditions and origin (genetics and early maternal effects) on telomere length of collared flycatchers (Ficedula albicollis) at fledging. We experimentally transferred hatchlings among brood triplets to create reduced, control (i.e. unchanged final nestling number) and enlarged broods. Results Although our treatment significantly affected body mass at fledging, we found no evidence that increased sibling competition affected nestling tarsus length and telomere length. However, mixed models showed that brood triplets explained a significant part of the variance in body mass (18%) and telomere length (19%), but not tarsus length (13%), emphasizing that unmanipulated early environmental factors influenced telomere length. These models also revealed low, but significant, heritability of telomere length (h2 = 0.09). For comparison, the heritability of nestling body mass and tarsus length was 0.36 and 0.39, respectively, which was in the range of previously published estimates for those two traits in this species. Conclusion Those findings in a wild bird population demonstrate that telomere length at the end of the growth period is weakly, but significantly, determined by genetic and/or maternal factors taking place before hatching. However, we found no evidence that the brood size manipulation experiment, and by extension the early growth conditions, influenced nestling telomere length. The weak heritability of telomere length suggests a close association with fitness in natural populations.
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Affiliation(s)
- Marie Voillemot
- Department of Ecology and Evolution, Biophore, University of Lausanne, Lausanne, Switzerland
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Wendland J, Walther A. Genome evolution in the eremothecium clade of the Saccharomyces complex revealed by comparative genomics. G3 (BETHESDA, MD.) 2011; 1:539-48. [PMID: 22384365 PMCID: PMC3276169 DOI: 10.1534/g3.111.001032] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/31/2011] [Accepted: 10/07/2011] [Indexed: 11/24/2022]
Abstract
We used comparative genomics to elucidate the genome evolution within the pre-whole-genome duplication genus Eremothecium. To this end, we sequenced and assembled the complete genome of Eremothecium cymbalariae, a filamentous ascomycete representing the Eremothecium type strain. Genome annotation indicated 4712 gene models and 143 tRNAs. We compared the E. cymbalariae genome with that of its relative, the riboflavin overproducer Ashbya (Eremothecium) gossypii, and the reconstructed yeast ancestor. Decisive changes in the Eremothecium lineage leading to the evolution of the A. gossypii genome include the reduction from eight to seven chromosomes, the downsizing of the genome by removal of 10% or 900 kb of DNA, mostly in intergenic regions, the loss of a TY3-Gypsy-type transposable element, the re-arrangement of mating-type loci, and a massive increase of its GC content. Key species-specific events are the loss of MNN1-family of mannosyltransferases required to add the terminal fourth and fifth α-1,3-linked mannose residue to O-linked glycans and genes of the Ehrlich pathway in E. cymbalariae and the loss of ZMM-family of meiosis-specific proteins and acquisition of riboflavin overproduction in A. gossypii. This reveals that within the Saccharomyces complex genome, evolution is not only based on genome duplication with subsequent gene deletions and chromosomal rearrangements but also on fungi associated with specific environments (e.g. involving fungal-insect interactions as in Eremothecium), which have encountered challenges that may be reflected both in genome streamlining and their biosynthetic potential.
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Affiliation(s)
| | - Andrea Walther
- Carlsberg Laboratory, Yeast Biology, Valby 2500, Denmark
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Fukunaga K, Hirano Y, Sugimoto K. Subtelomere-binding protein Tbf1 and telomere-binding protein Rap1 collaborate to inhibit localization of the Mre11 complex to DNA ends in budding yeast. Mol Biol Cell 2011; 23:347-59. [PMID: 22130795 PMCID: PMC3258178 DOI: 10.1091/mbc.e11-06-0568] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Rap1 acts together with the subtelomere-binding protein Tbf1 and inhibits localization of Mre11 complex to DNA ends. Depletion of Tbf1 protein stimulates checkpoint activation in cells containing short telomeres. The results suggest that Tbf1 and Rap1 collaborate to maintain genomic stability of short telomeres. Chromosome ends, known as telomeres, have to be distinguished from DNA double-strand breaks that activate DNA damage checkpoints. In budding yeast, the Mre11-Rad50-Xrs2 (MRX) complex associates with DNA ends and promotes checkpoint activation. Rap1 binds to double-stranded telomeric regions and recruits Rif1 and Rif2 to telomeres. Rap1 collaborates with Rif1 and Rif2 and inhibits MRX localization to DNA ends. This Rap1-Rif1-Rif2 function becomes attenuated at shortened telomeres. Here we show that Rap1 acts together with the subtelomere-binding protein Tbf1 and inhibits MRX localization to DNA ends. The placement of a subtelomeric sequence or TTAGGG repeats together with a short telomeric TG repeat sequence inhibits MRX accumulation at nearby DNA ends in a Tbf1-dependent manner. Moreover, tethering of both Tbf1 and Rap1 proteins decreases MRX and Tel1 accumulation at nearby DNA ends. This Tbf1- and Rap1-dependent pathway operates independently of Rif1 or Rif2 function. Depletion of Tbf1 protein stimulates checkpoint activation in cells containing short telomeres but not in cells containing normal-length telomeres. These data support a model in which Tbf1 and Rap1 collaborate to maintain genomic stability of short telomeres.
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Affiliation(s)
- Kenzo Fukunaga
- Department of Microbiology and Molecular Genetics, University of Medicine and Dentistry of New Jersey-New Jersey Medical School, Newark, NJ 07103, USA
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Becerra SC, Thambugala HT, Erickson AR, Lee CK, Lewis LK. Reversibility of replicative senescence in Saccharomyces cerevisiae: effect of homologous recombination and cell cycle checkpoints. DNA Repair (Amst) 2011; 11:35-45. [PMID: 22071150 DOI: 10.1016/j.dnarep.2011.10.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2011] [Revised: 10/01/2011] [Accepted: 10/04/2011] [Indexed: 12/13/2022]
Abstract
Primary human somatic cells grown in culture divide a finite number of times, exhibiting progressive changes in metabolism and morphology before cessation of cycling. This telomere-initiated cellular senescence occurs because cells have halted production of telomerase, a DNA polymerase required for stabilization of chromosome ends. Telomerase-deficient Saccharomyces cerevisiae cells undergo a similar process, with most cells arresting growth after approximately 60 generations. In the current study we demonstrate that senescence is largely reversible. Reactivation of telomerase (EST2) expression in the growth-arrested cells led to resumption of cycling and reversal of senescent cell characteristics. Rescue was also observed after mating of senescent haploid cells with telomerase-proficient cells to form stable diploids. Although senescence was reversible in DNA damage checkpoint response mutants (mec3 and/or rad24 cells), survival of recombination-defective rad52 mutants remained low after telomerase reactivation. Telomere lengths in rescued est2 cells were initially half those of wildtype cells, but could be restored to normal by propagation for ∼70 generations in the presence of telomerase. These results place limitations on possible models for senescence and indicate that most cells, despite gross morphological changes and short, resected telomeres, do not experience lethal DNA damage and become irreversibly committed to death.
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Affiliation(s)
- Sandra C Becerra
- Department of Chemistry and Biochemistry, Texas State University, San Marcos, TX 78666, USA
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27
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Grach AA. Alternative telomere-lengthening mechanisms. CYTOL GENET+ 2011. [DOI: 10.3103/s0095452711020046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Dot1 binding induces chromatin rearrangements by histone methylation-dependent and -independent mechanisms. Epigenetics Chromatin 2011; 4:2. [PMID: 21291527 PMCID: PMC3038881 DOI: 10.1186/1756-8935-4-2] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2010] [Accepted: 02/03/2011] [Indexed: 11/27/2022] Open
Abstract
Background Methylation of histone H3 lysine 79 (H3K79) by Dot1 is highly conserved among species and has been associated with both gene repression and activation. To eliminate indirect effects and examine the direct consequences of Dot1 binding and H3K79 methylation, we investigated the effects of targeting Dot1 to different positions in the yeast genome. Results Targeting Dot1 did not activate transcription at a euchromatic locus. However, chromatin-bound Dot1 derepressed heterochromatin-mediated gene silencing over a considerable distance. Unexpectedly, Dot1-mediated derepression was established by both a H3K79 methylation-dependent and a methylation-independent mechanism; the latter required the histone acetyltransferase Gcn5. By monitoring the localization of a fluorescently tagged telomere in living cells, we found that the targeting of Dot1, but not its methylation activity, led to the release of a telomere from the repressive environment at the nuclear periphery. This probably contributes to the activity-independent derepression effect of Dot1. Conclusions Targeting of Dot1 promoted gene expression by antagonizing gene repression through both histone methylation and chromatin relocalization. Our findings show that binding of Dot1 to chromatin can positively affect local gene expression by chromatin rearrangements over a considerable distance.
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Flueck C, Bartfai R, Niederwieser I, Witmer K, Alako BTF, Moes S, Bozdech Z, Jenoe P, Stunnenberg HG, Voss TS. A major role for the Plasmodium falciparum ApiAP2 protein PfSIP2 in chromosome end biology. PLoS Pathog 2010; 6:e1000784. [PMID: 20195509 PMCID: PMC2829057 DOI: 10.1371/journal.ppat.1000784] [Citation(s) in RCA: 122] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2009] [Accepted: 01/20/2010] [Indexed: 12/30/2022] Open
Abstract
The heterochromatic environment and physical clustering of chromosome ends at the nuclear periphery provide a functional and structural framework for antigenic variation and evolution of subtelomeric virulence gene families in the malaria parasite Plasmodium falciparum. While recent studies assigned important roles for reversible histone modifications, silent information regulator 2 and heterochromatin protein 1 (PfHP1) in epigenetic control of variegated expression, factors involved in the recruitment and organization of subtelomeric heterochromatin remain unknown. Here, we describe the purification and characterization of PfSIP2, a member of the ApiAP2 family of putative transcription factors, as the unknown nuclear factor interacting specifically with cis-acting SPE2 motif arrays in subtelomeric domains. Interestingly, SPE2 is not bound by the full-length protein but rather by a 60kDa N-terminal domain, PfSIP2-N, which is released during schizogony. Our experimental re-definition of the SPE2/PfSIP2-N interaction highlights the strict requirement of both adjacent AP2 domains and a conserved bipartite SPE2 consensus motif for high-affinity binding. Genome-wide in silico mapping identified 777 putative binding sites, 94% of which cluster in heterochromatic domains upstream of subtelomeric var genes and in telomere-associated repeat elements. Immunofluorescence and chromatin immunoprecipitation (ChIP) assays revealed co-localization of PfSIP2-N with PfHP1 at chromosome ends. Genome-wide ChIP demonstrated the exclusive binding of PfSIP2-N to subtelomeric SPE2 landmarks in vivo but not to single chromosome-internal sites. Consistent with this specialized distribution pattern, PfSIP2-N over-expression has no effect on global gene transcription. Hence, contrary to the previously proposed role for this factor in gene activation, our results provide strong evidence for the first time for the involvement of an ApiAP2 factor in heterochromatin formation and genome integrity. These findings are highly relevant for our understanding of chromosome end biology and variegated expression in P. falciparum and other eukaryotes, and for the future analysis of the role of ApiAP2-DNA interactions in parasite biology.
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Affiliation(s)
- Christian Flueck
- Department of Medical Parasitology and Infection Biology, Swiss Tropical Institute, University of Basel, Basel, Switzerland
| | - Richard Bartfai
- Department of Molecular Biology, Nijmegen Center of Molecular Life Sciences, Radboud University, Nijmegen, The Netherlands
| | - Igor Niederwieser
- Department of Medical Parasitology and Infection Biology, Swiss Tropical Institute, University of Basel, Basel, Switzerland
| | - Kathrin Witmer
- Department of Medical Parasitology and Infection Biology, Swiss Tropical Institute, University of Basel, Basel, Switzerland
| | - Blaise T. F. Alako
- Department of Molecular Biology, Nijmegen Center of Molecular Life Sciences, Radboud University, Nijmegen, The Netherlands
| | - Suzette Moes
- Biozentrum, University of Basel, Basel, Switzerland
| | - Zbynek Bozdech
- School of Biological Sciences, Nanyang Technological University, Singapore
| | - Paul Jenoe
- Biozentrum, University of Basel, Basel, Switzerland
| | - Hendrik G. Stunnenberg
- Department of Molecular Biology, Nijmegen Center of Molecular Life Sciences, Radboud University, Nijmegen, The Netherlands
| | - Till S. Voss
- Department of Medical Parasitology and Infection Biology, Swiss Tropical Institute, University of Basel, Basel, Switzerland
- * E-mail:
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Hernandez-Caballero E, Herrera-Gonzalez NE, Salamanca-Gomez F, Arenas-Aranda DJ. Role of telomere length in subtelomeric gene expression and its possible relation to cellular senescence. BMB Rep 2009; 42:747-51. [PMID: 19944017 DOI: 10.5483/bmbrep.2009.42.11.747] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Transcriptional silencing of subtelomeric genes is associated with telomere length, which is correlated with age. Long and short telomeres in young and old people, respectively, coincide with gene repression and activation in each case. In addition, differential location of genes with respect to telomeres causes telomere position effect. There is very little evidence of the manner in which age-related telomere length affects the expression of specific human subtelomeric genes. We analyzed the relationship between telomere length and gene expression levels in fibroblasts derived from human donors at ages ranging from 0-70 years. We studied three groups of genes located between 100 and 150 kb, 200 and 250 kb, and > 300 kb away from telomeres. We found that the chromatin modifier-encoding genes Eu-HMTase1, ZMYND11, and RASA3 were overexpressed in adults. Our results suggest that short telomere length-related overexpression of chromatin modifiers could underlie transcriptional changes contributing to cellular senescence.
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Affiliation(s)
- E Hernandez-Caballero
- Unidad de Investigacion Medica en Genetica Humana, Centro Medico Nacional Siglo XXI (CMN SXXI), Instituto Mexicano del Seguro Social (IMSS), Mexico City, Mexico
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31
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Verstrepen KJ, Fink GR. Genetic and epigenetic mechanisms underlying cell-surface variability in protozoa and fungi. Annu Rev Genet 2009; 43:1-24. [PMID: 19640229 DOI: 10.1146/annurev-genet-102108-134156] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Eukaryotic microorganisms have evolved ingenious mechanisms to generate variability at their cell surface, permitting differential adherence, rapid adaptation to changing environments, and evasion of immune surveillance. Fungi such as Saccharomyces cerevisiae and the pathogen Candida albicans carry a family of mucin and adhesin genes that allow adhesion to various surfaces and tissues. Trypanosoma cruzi, T. brucei, and Plasmodium falciparum likewise contain large arsenals of different cell surface adhesion genes. In both yeasts and protozoa, silencing and differential expression of the gene family results in surface variability. Here, we discuss unexpected similarities in the structure and genomic location of the cell surface genes, the role of repeated DNA sequences, and the genetic and epigenetic mechanisms-all of which contribute to the remarkable cell surface variability in these highly divergent microbes.
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32
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Taming the tiger by the tail: modulation of DNA damage responses by telomeres. EMBO J 2009; 28:2174-87. [PMID: 19629039 PMCID: PMC2722249 DOI: 10.1038/emboj.2009.176] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2009] [Accepted: 06/03/2009] [Indexed: 11/09/2022] Open
Abstract
Telomeres are by definition stable and inert chromosome ends, whereas internal chromosome breaks are potent stimulators of the DNA damage response (DDR). Telomeres do not, as might be expected, exclude DDR proteins from chromosome ends but instead engage with many DDR proteins. However, the most powerful DDRs, those that might induce chromosome fusion or cell-cycle arrest, are inhibited at telomeres. In budding yeast, many DDR proteins that accumulate most rapidly at double strand breaks (DSBs), have important functions in physiological telomere maintenance, whereas DDR proteins that arrive later tend to have less important functions. Considerable diversity in telomere structure has evolved in different organisms and, perhaps reflecting this diversity, different DDR proteins seem to have distinct roles in telomere physiology in different organisms. Drawing principally on studies in simple model organisms such as budding yeast, in which many fundamental aspects of the DDR and telomere biology have been established; current views on how telomeres harness aspects of DDR pathways to maintain telomere stability and permit cell-cycle division are discussed.
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33
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Casafont I, Bengoechea R, Tapia O, Berciano MT, Lafarga M. TDP-43 localizes in mRNA transcription and processing sites in mammalian neurons. J Struct Biol 2009; 167:235-41. [PMID: 19539030 DOI: 10.1016/j.jsb.2009.06.006] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2009] [Revised: 06/04/2009] [Accepted: 06/10/2009] [Indexed: 12/30/2022]
Abstract
TDP-43 is a RNA/DNA-binding protein structurally related to nuclear hnRNP proteins. Previous biochemical studies have shown that this nuclear protein plays a role in the regulation of gene transcription, alternative splicing and mRNA stability. Despite the ubiquitous distribution of TDP-43, the growing list of TDP-43 proteinopathies is primarily associated with neurodegenerative disorders. Particularly, TDP-43 redistributes to the cytoplasm and forms pathological inclusions in amyotrophic lateral sclerosis and several forms of sporadic and familiar frontotemporal lobar degeneration. Here, we have studied the nuclear compartmentalization of TDP-43 in normal rat neurons by using light and electron microscopy immunocytochemistry with molecular markers for nuclear compartments, a transcription assay with 5'-fluorouridine, and in situ hybridization for telomeric DNA. TDP-43 is concentrated in euchromatin domains, specifically in perichromatin fibrils, nuclear sites of transcription and cotranscriptional splicing. In these structures, TDP-43 colocalizes with 5'-fluorouridine incorporation sites into nascent pre-mRNA. TDP-43 is absent in transcriptionally silent centromeric and telomeric heterochromatin, as well as in the Cajal body, a transcription free nuclear compartment. Furthermore, a weak TDP-43 immunolabeling is found in nuclear speckles of splicing factors. The specific localization of TDP-43 in active sites of transcription and cotranscriptional splicing is consistent with biochemical data indicating a role of TDP-43 in the regulation of transcription and alternative splicing.
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Affiliation(s)
- Iñigo Casafont
- Department of Anatomy and Cell Biology and Centro de Investigación Biomedica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), University of Cantabria, 39011 Santander, Spain
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Mak HC, Pillus L, Ideker T. Dynamic reprogramming of transcription factors to and from the subtelomere. Genome Res 2009; 19:1014-25. [PMID: 19372386 DOI: 10.1101/gr.084178.108] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Transcription factors are most commonly thought of as proteins that regulate expression of specific genes, independently of the order of those genes along the chromosome. By screening genome-wide chromatin immunoprecipitation (ChIP) profiles in yeast, we find that more than 10% of DNA-binding transcription factors concentrate at the subtelomeric regions near to chromosome ends. None of the proteins identified were previously implicated in regulation at telomeres, yet genomic and proteomic studies reveal that a subset of factors show many interactions with established telomere binding complexes. For many factors, the subtelomeric binding pattern is dynamic and undergoes flux toward or away from the telomere as physiological conditions shift. We find that subtelomeric binding is dependent on environmental conditions and correlates with the induction of gene expression in response to stress. Taken together, these results underscore the importance of genome structure in understanding the regulatory dynamics of transcriptional networks.
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Affiliation(s)
- H Craig Mak
- Division of Biological Sciences, University of California San Diego, La Jolla, California 92093, USA
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35
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Ebrahimi H, Donaldson AD. Release of yeast telomeres from the nuclear periphery is triggered by replication and maintained by suppression of Ku-mediated anchoring. Genes Dev 2009; 22:3363-74. [PMID: 19056887 DOI: 10.1101/gad.486208] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The perinuclear localization of Saccharomyces cerevisiae telomeres provides a useful model for studying mechanisms that control chromosome positioning. Telomeres tend to be localized at the nuclear periphery during early interphase, but following S phase they delocalize and remain randomly positioned within the nucleus. We investigated whether DNA replication causes telomere delocalization from the nuclear periphery. Using live-cell fluorescence microscopy, we show that delaying DNA replication causes a corresponding delay in the dislodgment of telomeres from the nuclear envelope, demonstrating that replication of individual telomeres causes their delocalization. Telomere delocalization is not simply the result of recruitment to a replication factory in the nuclear interior, since we found that telomeric DNA replication can occur either at the nuclear periphery or in the nuclear interior. The telomere-binding complex Ku is one of the factors that localizes telomeres to the nuclear envelope. Using a gene locus tethering assay, we show that Ku-mediated peripheral positioning is switched off after DNA replication. Based on these findings, we propose that DNA replication causes telomere delocalization by triggering stable repression of the Ku-mediated anchoring pathway. In addition to maintaining genetic information, DNA replication may therefore regulate subnuclear organization of chromatin.
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Affiliation(s)
- Hani Ebrahimi
- Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, Scotland, United Kingdom
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36
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Doheny JG, Mottus R, Grigliatti TA. Telomeric position effect--a third silencing mechanism in eukaryotes. PLoS One 2008; 3:e3864. [PMID: 19057646 PMCID: PMC2587703 DOI: 10.1371/journal.pone.0003864] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2008] [Accepted: 10/20/2008] [Indexed: 12/29/2022] Open
Abstract
Eukaryotic chromosomes terminate in telomeres, complex nucleoprotein structures that are required for chromosome integrity that are implicated in cellular senescence and cancer. The chromatin at the telomere is unique with characteristics of both heterochromatin and euchromatin. The end of the chromosome is capped by a structure that protects the end and is required for maintaining proper chromosome length. Immediately proximal to the cap are the telomere associated satellite-like (TAS) sequences. Genes inserted into the TAS sequences are silenced indicating the chromatin environment is incompatible with transcription. This silencing phenomenon is called telomeric position effect (TPE). Two other silencing mechanisms have been identified in eukaryotes, suppressors position effect variegation [Su(var)s, greater than 30 members] and Polycomb group proteins (PcG, approximately 15 members). We tested a large number of each group for their ability to suppress TPE [Su(TPE)]. Our results showed that only three Su(var)s and only one PcG member are involved in TPE, suggesting silencing in the TAS sequences occurs via a novel silencing mechanism. Since, prior to this study, only five genes have been identified that are Su(TPE)s, we conducted a candidate screen for Su(TPE) in Drosophila by testing point mutations in, and deficiencies for, proteins involved in chromatin metabolism. Screening with point mutations identified seven new Su(TPE)s and the deficiencies identified 19 regions of the Drosophila genome that harbor suppressor mutations. Chromatin immunoprecipitation experiments on a subset of the new Su(TPE)s confirm they act directly on the gene inserted into the telomere. Since the Su(TPE)s do not overlap significantly with either PcGs or Su(var)s, and the candidates were selected because they are involved generally in chromatin metabolism and act at a wide variety of sites within the genome, we propose that the Su(TPE) represent a third, widely used, silencing mechanism in the eukaryotic genome.
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Affiliation(s)
- J. Greg Doheny
- Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Randy Mottus
- Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Thomas A. Grigliatti
- Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada
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37
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Mason JM, Frydrychova RC, Biessmann H. Drosophila telomeres: an exception providing new insights. Bioessays 2008; 30:25-37. [PMID: 18081009 DOI: 10.1002/bies.20688] [Citation(s) in RCA: 98] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Drosophila telomeres comprise DNA sequences that differ dramatically from those of other eukaryotes. Telomere functions, however, are similar to those found in telomerase-based telomeres, even though the underlying mechanisms may differ. Drosophila telomeres use arrays of retrotransposons to maintain chromosome length, while nearly all other eukaryotes rely on telomerase-generated short repeats. Regardless of the DNA sequence, several end-binding proteins are evolutionarily conserved. Away from the end, the Drosophila telomeric and subtelomeric DNA sequences are complexed with unique combinations of proteins that also modulate chromatin structure elsewhere in the genome. Maintaining and regulating the transcriptional activity of the telomeric retrotransposons in Drosophila requires specific chromatin structures and, while telomeric silencing spreads from the terminal repeats in yeast, the source of telomeric silencing in Drosophila is the subterminal arrays. However, the subterminal arrays in both species may be involved in telomere-telomere associations and/or communication.
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Affiliation(s)
- James M Mason
- Laboratory of Molecular Genetics, National Institute of Environmental Health Sciences, Research Triangle Park, NC, USA
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38
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Abstract
The budding yeast species Saccharomyces castellii has provided important new insights into molecular evolution when incorporated in comparative genomics studies and studies of mitochondrial inheritage. Although it shows some diversity in the specific molecular details, several analyses have shown that it contains many genetic pathways similar to those of S. cerevisiae. Here we have investigated the possibility of performing genetic analyses in S. castellii. We optimized the LiAc transformation protocol to achieve 200-300 transformants/microg plasmid DNA. We found that the commonly used plasmids for S. cerevisiae are stably maintained in S. castellii under selective conditions. Surprisingly, both 2micro and CEN/ARS plasmids are kept at a high copy number. Moreover, the kanMX cassette can be used as a resistance marker against the selective drug geneticin (G418). Finally, we determined that the S. cerevisiae GAL1 promoter can be used for the activation of transcription in S. castellii, thus enabling the controlled overexpression of genes when galactose is present in the medium. The availability of these tools provides the possibility of performing genetic analyses in S. castellii, and makes it a promising new model system in which hypotheses derived from bioinformatics studies can be experimentally tested.
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39
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Zhdanova NS, Rubtsov NB, Minina YM. Terminal regions of mammal chromosomes: Plasticity and role in evolution. RUSS J GENET+ 2007. [DOI: 10.1134/s1022795407070022] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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40
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Zellinger B, Riha K. Composition of plant telomeres. ACTA ACUST UNITED AC 2007; 1769:399-409. [PMID: 17383025 DOI: 10.1016/j.bbaexp.2007.02.001] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2006] [Revised: 02/01/2007] [Accepted: 02/09/2007] [Indexed: 12/15/2022]
Abstract
Telomeres are essential elements of eukaryotic chromosomes that differentiate native chromosome ends from deleterious DNA double-strand breaks (DSBs). This is achieved by assembling chromosome termini in elaborate high-order nucleoprotein structures that in most organisms encompass telomeric DNA, specific telomere-associated proteins as well as general chromatin and DNA repair factors. Although the individual components of telomeric chromatin are evolutionary highly conserved, cross species comparisons have revealed a remarkable flexibility in their utilization at telomeres. This review outlines the strategies used for chromosome end protection and maintenance in mammals, yeast and flies and discusses current progress in deciphering telomere structure in plants.
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Affiliation(s)
- Barbara Zellinger
- Gregor Mendel Institute of Plant Molecular Biology, Austrian Academy of Sciences, Dr. Bohrgasse 3, A-1030 Vienna, Austria
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41
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Bianchi A, Shore D. Early Replication of Short Telomeres in Budding Yeast. Cell 2007; 128:1051-62. [PMID: 17382879 DOI: 10.1016/j.cell.2007.01.041] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2006] [Revised: 11/20/2006] [Accepted: 01/15/2007] [Indexed: 11/17/2022]
Abstract
The maintenance of an appropriate number of telomere repeats by telomerase is essential for proper chromosome protection. The action of telomerase at the telomere terminus is regulated by opposing activities that either recruit/activate the enzyme at shorter telomeres or inhibit it at longer ones, thus achieving a stable average telomere length. To elucidate the mechanistic details of telomerase regulation we engineered specific chromosome ends in yeast so that a single telomere could be suddenly shortened and, as a consequence of its reduced length, elongated by telomerase. We show that shortened telomeres replicate early in S phase, unlike normal-length telomeres, due to the early firing of origins of DNA replication in subtelomeric regions. Early telomere replication correlates with increased telomere length and telomerase activity. These data reveal an epigenetic effect of telomere length on the activity of nearby replication origins and an unanticipated link between telomere replication timing and telomerase action.
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Affiliation(s)
- Alessandro Bianchi
- Department of Molecular Biology and NCCR Frontiers in Genetics Program, University of Geneva, Geneva, Switzerland.
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Berciano MT, Novell M, Villagra NT, Casafont I, Bengoechea R, Val-Bernal JF, Lafarga M. Cajal body number and nucleolar size correlate with the cell body mass in human sensory ganglia neurons. J Struct Biol 2006; 158:410-20. [PMID: 17275332 DOI: 10.1016/j.jsb.2006.12.008] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2006] [Revised: 12/21/2006] [Accepted: 12/21/2006] [Indexed: 12/29/2022]
Abstract
This paper studies the cell size-dependent organization of the nucleolus and Cajal bodies (CBs) in dissociated human dorsal root ganglia (DRG) neurons from autopsy tissue samples of patients without neurological disease. The quantitative analysis of nucleoli with an anti-fibrillarin antibody showed that all neurons have only one nucleolus. However, the nucleolar volume and the number of fibrillar centers per nucleolus significantly increase as a function of cell body size. Immunostaining for coilin demonstrated the presence of numerous CBs in DRG neurons (up to 20 in large size neurons). The number of CBs per neuron correlated positively with the cell body volume. Light and electron microscopy immunocytochemical analysis revealed the concentration of coilin, snRNPs, SMN and fibrillarin in CBs of DRG neurons. CBs were frequently associated with the nucleolus, active chromatin domains and PML bodies, but not with telomeres. Our results support the view that the nucleolar volume and number of both fibrillar centers and CBs depend on the cell body mass, a parameter closely related to transcriptional and synaptic activity in mammalian neurons. Moreover, the unusual large number of CBs could facilitate the transfer of RNA processing components from CBs to nucleolar and nucleoplasmic sites of RNA processing.
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Affiliation(s)
- Maria T Berciano
- Department of Anatomy and Cell Biology, and Biomedicine Unit (CSIC), University of Cantabria, Santander, Spain
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43
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44
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Casafont I, Navascués J, Pena E, Lafarga M, Berciano MT. Nuclear organization and dynamics of transcription sites in rat sensory ganglia neurons detected by incorporation of 5'-fluorouridine into nascent RNA. Neuroscience 2006; 140:453-62. [PMID: 16563640 DOI: 10.1016/j.neuroscience.2006.02.030] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2005] [Revised: 02/09/2006] [Accepted: 02/10/2006] [Indexed: 01/08/2023]
Abstract
In this study we have used the transcription assay with 5'-fluorouridine incorporation into nascent RNA to analyze the nuclear organization and dynamics of transcription sites in rat trigeminal ganglia neurons. The 5'-FU administrated by i.p. injection was successfully incorporated into nuclear domains containing actively transcribing genes of trigeminal neurons. 5'-Fluorouridine RNA-labeling was detected with immunocytochemistry at light and electron microscopy levels. The 5'-fluorouridine incorporation sites were detected in the nucleolus, particularly on the dense fibrillar component, and in numerous transcription foci spread throughout the euchromatin regions, without preferential positioning at the nuclear periphery or in the nuclear interior. Double labeling experiments to combine 5'-fluorouridine incorporation with molecular markers of nuclear compartments showed the absence of transcription sites in Cajal bodies and nuclear speckles of splicing factors. Similarly, no 5'-fluorouridine labeling was detected in well-characterized chromatin silencing domain, the telomeric heterochromatin. The specificity and sensitivity of the run-on transcription assay in trigeminal ganglia neurons was verified by the i.p. administration of the transcription inhibitor actinomycin D. The dramatic reduction in RNA synthesis upon actinomycin D treatment was associated with two important cellular events, heterochromatin silencing and formation of DNA damage/repair nuclear foci, demonstrated by the expression of tri-methylated histone H4 and phosphorylated H2AX, respectively. 5'-Fluorouridine incorporation in animal models provides a useful tool to investigate the organization of gene expression in mammalian neurons in both normal physiology and experimental pathology systems.
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Affiliation(s)
- I Casafont
- Department of Anatomy and Cell Biology and Biomedicine Unit, CSIC, University of Cantabria, Avd. Cardenal Herrera Oria, s/n, 39011 Santander, Spain
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Abstract
Over the past decade, the human identity testing community has settled on a set of core short tandem repeat (STR) loci that are widely used for DNA typing applications. A variety of commercial kits enable robust amplification of these core STR loci. A brief history is presented regarding the selection of core autosomal and Y-chromosomal STR markers. The physical location of each STR locus in the human genome is delineated and allele ranges and variants observed in human populations are summarized as are mutation rates observed from parentage testing. Internet resources for additional information on core STR loci are reviewed. Additional topics are also discussed, including potential linkage of STR loci to genetic disease-causing genes, probabilistic predictions of sample ethnicity, and desirable characteristics for additional STR loci that may be added in the future to the current core loci. These core STR loci, which form the basis for DNA databases worldwide, will continue to play an important role in forensic science for many years to come.
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Affiliation(s)
- John M Butler
- National Institute of Standards and Technology, Gaithersburg, MD 20899-8311, USA.
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Bolzán AD, Bianchi MS. Telomeres, interstitial telomeric repeat sequences, and chromosomal aberrations. Mutat Res 2006; 612:189-214. [PMID: 16490380 DOI: 10.1016/j.mrrev.2005.12.003] [Citation(s) in RCA: 106] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2005] [Revised: 12/29/2005] [Accepted: 12/30/2005] [Indexed: 11/18/2022]
Abstract
Telomeres are specialized nucleoproteic complexes localized at the physical ends of linear eukaryotic chromosomes that maintain their stability and integrity. The DNA component of telomeres is characterized by being a G-rich double stranded DNA composed by short fragments tandemly repeated with different sequences depending on the species considered. At the chromosome level, telomeres or, more properly, telomeric repeats--the DNA component of telomeres--can be detected either by using the fluorescence in situ hybridization (FISH) technique with a DNA or a peptide nucleic acid (PNA) (pan)telomeric probe, i.e., which identifies simultaneously all of the telomeres in a metaphase cell, or by the primed in situ labeling (PRINS) reaction using an oligonucleotide primer complementary to the telomeric DNA repeated sequence. Using these techniques, incomplete chromosome elements, acentric fragments, amplification and translocation of telomeric repeat sequences, telomeric associations and telomeric fusions can be identified. In addition, chromosome orientation (CO)-FISH allows to discriminate between the different types of telomeric fusions, namely telomere-telomere and telomere-DNA double strand break fusions and to detect recombination events at the telomere, i.e., telomeric sister-chromatid exchanges (T-SCE). In this review, we summarize our current knowledge of chromosomal aberrations involving telomeres and interstitial telomeric repeat sequences and their induction by physical and chemical mutagens. Since all of the studies on the induction of these types of aberrations were conducted in mammalian cells, the review will be focused on the chromosomal aberrations involving the TTAGGG sequence, i.e., the telomeric repeat sequence that "caps" the chromosomes of all vertebrate species.
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Affiliation(s)
- Alejandro D Bolzán
- Laboratorio de Citogenética y Mutagénesis, Instituto Multidisciplinario de Biología Celular (IMBICE), C.C. 403, 1900 La Plata, Argentina.
| | - Martha S Bianchi
- Laboratorio de Citogenética y Mutagénesis, Instituto Multidisciplinario de Biología Celular (IMBICE), C.C. 403, 1900 La Plata, Argentina
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Monaghan P, Haussmann MF. Do telomere dynamics link lifestyle and lifespan? Trends Ecol Evol 2006; 21:47-53. [PMID: 16701469 DOI: 10.1016/j.tree.2005.11.007] [Citation(s) in RCA: 236] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2005] [Revised: 10/17/2005] [Accepted: 11/08/2005] [Indexed: 01/12/2023]
Abstract
Identifying and understanding the processes that underlie the observed variation in lifespan within and among species remains one of the central areas of biological research. Questions directed at how, at what rate and why organisms grow old and die link disciplines such as evolutionary ecology to those of cell biology and gerontology. One process now thought to have a key role in ageing is the pattern of erosion of the protective ends of chromosomes, the telomeres. Here, we discuss what is currently known about the factors influencing telomere regulation, and how this relates to fundamental questions about the relationship between lifestyle and lifespan.
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Affiliation(s)
- Pat Monaghan
- Division of Environmental & Evolutionary Biology, Institute of Biomedical and Life Sciences, Glasgow University, Glasgow G12 8QQ, UK.
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