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Agabekian IA, Abdulkina LR, Lushnenko AY, Young PG, Valeeva LR, Boskovic O, Lilly EG, Sharipova MR, Shippen DE, Juenger TE, Shakirov EV. Arabidopsis AN3 and OLIGOCELLULA genes link telomere maintenance mechanisms with cell division and expansion control. PLANT MOLECULAR BIOLOGY 2024; 114:65. [PMID: 38816532 DOI: 10.1007/s11103-024-01457-6] [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: 10/12/2023] [Accepted: 04/23/2024] [Indexed: 06/01/2024]
Abstract
Telomeres are conserved chromosomal structures necessary for continued cell division and proliferation. In addition to the classical telomerase pathway, multiple other genes including those involved in ribosome metabolism and chromatin modification contribute to telomere length maintenance. We previously reported that Arabidopsis thaliana ribosome biogenesis genes OLI2/NOP2A, OLI5/RPL5A and OLI7/RPL5B have critical roles in telomere length regulation. These three OLIGOCELLULA genes were also shown to function in cell proliferation and expansion control and to genetically interact with the transcriptional co-activator ANGUSTIFOLIA3 (AN3). Here we show that AN3-deficient plants progressively lose telomeric DNA in early homozygous mutant generations, but ultimately establish a new shorter telomere length setpoint by the fifth mutant generation with a telomere length similar to oli2/nop2a -deficient plants. Analysis of double an3 oli2 mutants indicates that the two genes are epistatic for telomere length control. Telomere shortening in an3 and oli mutants is not caused by telomerase inhibition; wild type levels of telomerase activity are detected in all analyzed mutants in vitro. Late generations of an3 and oli mutants are prone to stem cell damage in the root apical meristem, implying that genes regulating telomere length may have conserved functional roles in stem cell maintenance mechanisms. Multiple instances of anaphase fusions in late generations of oli5 and oli7 mutants were observed, highlighting an unexpected effect of ribosome biogenesis factors on chromosome integrity. Overall, our data implicate AN3 transcription coactivator and OLIGOCELLULA proteins in the establishment of telomere length set point in plants and further suggest that multiple regulators with pleiotropic functions can connect telomere biology with cell proliferation and cell expansion pathways.
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Affiliation(s)
- Inna A Agabekian
- Institute of Fundamental Medicine and Biology, Kazan Federal University, Republic of Tatarstan, Kazan, 420008, Russia
| | - Liliia R Abdulkina
- Institute of Fundamental Medicine and Biology, Kazan Federal University, Republic of Tatarstan, Kazan, 420008, Russia
| | - Alina Y Lushnenko
- Institute of Fundamental Medicine and Biology, Kazan Federal University, Republic of Tatarstan, Kazan, 420008, Russia
| | - Pierce G Young
- Department of Biochemistry and Biophysics, Texas A&M University, 2128 TAMU, College Station, Texas, 77843-2128, USA
| | - Lia R Valeeva
- Department of Biological Sciences, College of Science, Marshall University, Huntington, West Virginia, 25701, USA
| | - Olivia Boskovic
- Department of Biological Sciences, College of Science, Marshall University, Huntington, West Virginia, 25701, USA
| | - Ethan G Lilly
- Department of Biological Sciences, College of Science, Marshall University, Huntington, West Virginia, 25701, USA
| | - Margarita R Sharipova
- Institute of Fundamental Medicine and Biology, Kazan Federal University, Republic of Tatarstan, Kazan, 420008, Russia
| | - Dorothy E Shippen
- Department of Biochemistry and Biophysics, Texas A&M University, 2128 TAMU, College Station, Texas, 77843-2128, USA.
| | - Thomas E Juenger
- Department of Integrative Biology, University of Texas at Austin, Austin, Texas, 78712, USA.
| | - Eugene V Shakirov
- Department of Biological Sciences, College of Science, Marshall University, Huntington, West Virginia, 25701, USA.
- Department of Biomedical Sciences, Joan C. Edwards School of Medicine, Marshall University, Huntington, West Virginia, 25755, USA.
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2
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Potential roles of telomeres and telomerase in neurodegenerative diseases. Int J Biol Macromol 2020; 163:1060-1078. [DOI: 10.1016/j.ijbiomac.2020.07.046] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Revised: 06/23/2020] [Accepted: 07/06/2020] [Indexed: 12/16/2022]
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Olivier M, Charbonnel C, Amiard S, White CI, Gallego ME. RAD51 and RTEL1 compensate telomere loss in the absence of telomerase. Nucleic Acids Res 2019; 46:2432-2445. [PMID: 29346668 PMCID: PMC5861403 DOI: 10.1093/nar/gkx1322] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2017] [Accepted: 01/09/2018] [Indexed: 11/23/2022] Open
Abstract
Replicative erosion of telomeres is naturally compensated by telomerase and studies in yeast and vertebrates show that homologous recombination can compensate for the absence of telomerase. We show that RAD51 protein, which catalyzes the key strand-invasion step of homologous recombination, is localized at Arabidopsis telomeres in absence of telomerase. Blocking the strand-transfer activity of the RAD51 in telomerase mutant plants results in a strikingly earlier onset of developmental defects, accompanied by increased numbers of end-to-end chromosome fusions. Imposing replication stress through knockout of RNaseH2 increases numbers of chromosome fusions and reduces the survival of these plants deficient for telomerase and homologous recombination. This finding suggests that RAD51-dependent homologous recombination acts as an essential backup to the telomerase for compensation of replicative telomere loss to ensure genome stability. Furthermore, we show that this positive role of RAD51 in telomere stability is dependent on the RTEL1 helicase. We propose that a RAD51 dependent break-induced replication process is activated in cells lacking telomerase activity, with RTEL1 responsible for D-loop dissolution after telomere replication.
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Affiliation(s)
- Margaux Olivier
- Génétique, Reproduction et Développement, UMR CNRS 6293 - INSERM U1103 - Université Clermont Auvergne, Faculté de Médecine. 28, place Henri Dunant - BP38 63001 Clermont-Ferrand Cedex 1, France
| | - Cyril Charbonnel
- Génétique, Reproduction et Développement, UMR CNRS 6293 - INSERM U1103 - Université Clermont Auvergne, Faculté de Médecine. 28, place Henri Dunant - BP38 63001 Clermont-Ferrand Cedex 1, France
| | - Simon Amiard
- Génétique, Reproduction et Développement, UMR CNRS 6293 - INSERM U1103 - Université Clermont Auvergne, Faculté de Médecine. 28, place Henri Dunant - BP38 63001 Clermont-Ferrand Cedex 1, France
| | - Charles I White
- Génétique, Reproduction et Développement, UMR CNRS 6293 - INSERM U1103 - Université Clermont Auvergne, Faculté de Médecine. 28, place Henri Dunant - BP38 63001 Clermont-Ferrand Cedex 1, France
| | - Maria E Gallego
- Génétique, Reproduction et Développement, UMR CNRS 6293 - INSERM U1103 - Université Clermont Auvergne, Faculté de Médecine. 28, place Henri Dunant - BP38 63001 Clermont-Ferrand Cedex 1, France
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Pontvianne F, Carpentier MC, Durut N, Pavlištová V, Jaške K, Schořová Š, Parrinello H, Rohmer M, Pikaard CS, Fojtová M, Fajkus J, Sáez-Vásquez J. Identification of Nucleolus-Associated Chromatin Domains Reveals a Role for the Nucleolus in 3D Organization of the A. thaliana Genome. Cell Rep 2016; 16:1574-1587. [PMID: 27477271 PMCID: PMC5279810 DOI: 10.1016/j.celrep.2016.07.016] [Citation(s) in RCA: 96] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Revised: 05/24/2016] [Accepted: 07/03/2016] [Indexed: 11/27/2022] Open
Abstract
The nucleolus is the site of rRNA gene transcription, rRNA processing, and ribosome biogenesis. However, the nucleolus also plays additional roles in the cell. We isolated nucleoli using fluorescence-activated cell sorting (FACS) and identified nucleolus-associated chromatin domains (NADs) by deep sequencing, comparing wild-type plants and null mutants for the nucleolar protein NUCLEOLIN 1 (NUC1). NADs are primarily genomic regions with heterochromatic signatures and include transposable elements (TEs), sub-telomeric regions, and mostly inactive protein-coding genes. However, NADs also include active rRNA genes and the entire short arm of chromosome 4 adjacent to them. In nuc1 null mutants, which alter rRNA gene expression and overall nucleolar structure, NADs are altered, telomere association with the nucleolus is decreased, and telomeres become shorter. Collectively, our studies reveal roles for NUC1 and the nucleolus in the spatial organization of chromosomes as well as telomere maintenance.
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Affiliation(s)
- Frédéric Pontvianne
- CNRS, Laboratoire Génome et Développement des Plantes, UMR5096, 66860 Perpignan, France; Université de Perpignan Via Domitia, Laboratoire Génome et Développement des Plantes, UMR5096, 66860 Perpignan, France; Department of Biology and Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN 47405, USA.
| | - Marie-Christine Carpentier
- CNRS, Laboratoire Génome et Développement des Plantes, UMR5096, 66860 Perpignan, France; Université de Perpignan Via Domitia, Laboratoire Génome et Développement des Plantes, UMR5096, 66860 Perpignan, France
| | - Nathalie Durut
- CNRS, Laboratoire Génome et Développement des Plantes, UMR5096, 66860 Perpignan, France; Université de Perpignan Via Domitia, Laboratoire Génome et Développement des Plantes, UMR5096, 66860 Perpignan, France
| | - Veronika Pavlištová
- Central European Institute of Technology and Faculty of Science, Masaryk University, 62500 Brno, Czech Republic
| | - Karin Jaške
- Central European Institute of Technology and Faculty of Science, Masaryk University, 62500 Brno, Czech Republic
| | - Šárka Schořová
- Central European Institute of Technology and Faculty of Science, Masaryk University, 62500 Brno, Czech Republic
| | | | | | - Craig S Pikaard
- Department of Biology and Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN 47405, USA; Howard Hughes Medical Institute, Indiana University, Bloomington, IN 47405, USA
| | - Miloslava Fojtová
- Central European Institute of Technology and Faculty of Science, Masaryk University, 62500 Brno, Czech Republic
| | - Jiří Fajkus
- Central European Institute of Technology and Faculty of Science, Masaryk University, 62500 Brno, Czech Republic
| | - Julio Sáez-Vásquez
- CNRS, Laboratoire Génome et Développement des Plantes, UMR5096, 66860 Perpignan, France; Université de Perpignan Via Domitia, Laboratoire Génome et Développement des Plantes, UMR5096, 66860 Perpignan, France
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Li X, Shahid MQ, Wu J, Wang L, Liu X, Lu Y. Comparative Small RNA Analysis of Pollen Development in Autotetraploid and Diploid Rice. Int J Mol Sci 2016; 17:499. [PMID: 27077850 PMCID: PMC4848955 DOI: 10.3390/ijms17040499] [Citation(s) in RCA: 73] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2015] [Revised: 03/24/2016] [Accepted: 03/28/2016] [Indexed: 11/21/2022] Open
Abstract
MicroRNAs (miRNAs) play key roles in plant reproduction. However, knowledge on microRNAome analysis in autotetraploid rice is rather limited. Here, high-throughput sequencing technology was employed to analyze miRNAomes during pollen development in diploid and polyploid rice. A total of 172 differentially expressed miRNAs (DEM) were detected in autotetraploid rice compared to its diploid counterpart, and 57 miRNAs were specifically expressed in autotetraploid rice. Of the 172 DEM, 115 and 61 miRNAs exhibited up- and down-regulation, respectively. Gene Ontology analysis on the targets of up-regulated DEM showed that they were enriched in transport and membrane in pre-meiotic interphase, reproduction in meiosis, and nucleotide binding in single microspore stage. osa-miR5788 and osa-miR1432-5p_R+1 were up-regulated in meiosis and their targets revealed interaction with the meiosis-related genes, suggesting that they may involve in the genes regulation associated with the chromosome behavior. Abundant 24 nt siRNAs associated with transposable elements were found in autotetraploid rice during pollen development; however, they significantly declined in diploid rice, suggesting that 24 nt siRNAs may play a role in pollen development. These findings provide a foundation for understanding the effect of polyploidy on small RNA expression patterns during pollen development that cause pollen sterility in autotetraploid rice.
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Affiliation(s)
- Xiang Li
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, South China Agricultural University, Guangzhou 510642, China.
| | - Muhammad Qasim Shahid
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, South China Agricultural University, Guangzhou 510642, China.
| | - Jinwen Wu
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, South China Agricultural University, Guangzhou 510642, China.
| | - Lan Wang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, South China Agricultural University, Guangzhou 510642, China.
| | - Xiangdong Liu
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, South China Agricultural University, Guangzhou 510642, China.
| | - Yonggen Lu
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, South China Agricultural University, Guangzhou 510642, China.
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6
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Procházková Schrumpfová P, Schořová Š, Fajkus J. Telomere- and Telomerase-Associated Proteins and Their Functions in the Plant Cell. FRONTIERS IN PLANT SCIENCE 2016; 7:851. [PMID: 27446102 PMCID: PMC4924339 DOI: 10.3389/fpls.2016.00851] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Accepted: 05/31/2016] [Indexed: 05/20/2023]
Abstract
Telomeres, as physical ends of linear chromosomes, are targets of a number of specific proteins, including primarily telomerase reverse transcriptase. Access of proteins to the telomere may be affected by a number of diverse factors, e.g., protein interaction partners, local DNA or chromatin structures, subcellular localization/trafficking, or simply protein modification. Knowledge of composition of the functional nucleoprotein complex of plant telomeres is only fragmentary. Moreover, the plant telomeric repeat binding proteins that were characterized recently appear to also be involved in non-telomeric processes, e.g., ribosome biogenesis. This interesting finding was not totally unexpected since non-telomeric functions of yeast or animal telomeric proteins, as well as of telomerase subunits, have been reported for almost a decade. Here we summarize known facts about the architecture of plant telomeres and compare them with the well-described composition of telomeres in other organisms.
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Affiliation(s)
- Petra Procházková Schrumpfová
- Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology, Masaryk UniversityBrno, Czech Republic
- Laboratory of Functional Genomics and Proteomics, National Centre for Biomolecular Research, Faculty of Science, Masaryk UniversityBrno, Czech Republic
- *Correspondence: Petra Procházková Schrumpfová,
| | - Šárka Schořová
- Laboratory of Functional Genomics and Proteomics, National Centre for Biomolecular Research, Faculty of Science, Masaryk UniversityBrno, Czech Republic
| | - Jiří Fajkus
- Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology, Masaryk UniversityBrno, Czech Republic
- Laboratory of Functional Genomics and Proteomics, National Centre for Biomolecular Research, Faculty of Science, Masaryk UniversityBrno, Czech Republic
- Institute of Biophysics, Academy of Sciences of the Czech Republic, v.v.i.Brno, Czech Republic
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7
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Missirian V, Conklin PA, Culligan KM, Huefner ND, Britt AB. High atomic weight, high-energy radiation (HZE) induces transcriptional responses shared with conventional stresses in addition to a core "DSB" response specific to clastogenic treatments. FRONTIERS IN PLANT SCIENCE 2014; 5:364. [PMID: 25136344 PMCID: PMC4117989 DOI: 10.3389/fpls.2014.00364] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2014] [Accepted: 07/08/2014] [Indexed: 05/19/2023]
Abstract
Plants exhibit a robust transcriptional response to gamma radiation which includes the induction of transcripts required for homologous recombination and the suppression of transcripts that promote cell cycle progression. Various DNA damaging agents induce different spectra of DNA damage as well as "collateral" damage to other cellular components and therefore are not expected to provoke identical responses by the cell. Here we study the effects of two different types of ionizing radiation (IR) treatment, HZE (1 GeV Fe(26+) high mass, high charge, and high energy relativistic particles) and gamma photons, on the transcriptome of Arabidopsis thaliana seedlings. Both types of IR induce small clusters of radicals that can result in the formation of double strand breaks (DSBs), but HZE also produces linear arrays of extremely clustered damage. We performed these experiments across a range of time points (1.5-24 h after irradiation) in both wild-type plants and in mutants defective in the DSB-sensing protein kinase ATM. The two types of IR exhibit a shared double strand break-repair-related damage response, although they differ slightly in the timing, degree, and ATM-dependence of the response. The ATM-dependent, DNA metabolism-related transcripts of the "DSB response" were also induced by other DNA damaging agents, but were not induced by conventional stresses. Both Gamma and HZE irradiation induced, at 24 h post-irradiation, ATM-dependent transcripts associated with a variety of conventional stresses; these were overrepresented for pathogen response, rather than DNA metabolism. In contrast, only HZE-irradiated plants, at 1.5 h after irradiation, exhibited an additional and very extensive transcriptional response, shared with plants experiencing "extended night." This response was not apparent in gamma-irradiated plants.
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Affiliation(s)
- Victor Missirian
- Department of Plant Biology, University of California DavisDavis, CA, USA
| | - Phillip A. Conklin
- Department of Plant Biology, University of California DavisDavis, CA, USA
| | - Kevin M. Culligan
- Department of Molecular, Cellular, and Biomedical Sciences, University of New HampshireDurham, NH, USA
| | - Neil D. Huefner
- Department of Plant Biology, University of California DavisDavis, CA, USA
| | - Anne B. Britt
- Department of Plant Biology, University of California DavisDavis, CA, USA
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Najdekrova L, Siroky J. NBS1 plays a synergistic role with telomerase in the maintenance of telomeres in Arabidopsis thaliana. BMC PLANT BIOLOGY 2012; 12:167. [PMID: 22985462 PMCID: PMC3490983 DOI: 10.1186/1471-2229-12-167] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2012] [Accepted: 09/10/2012] [Indexed: 05/29/2023]
Abstract
BACKGROUND Telomeres, as elaborate nucleo-protein complexes, ensure chromosomal stability. When impaired, the ends of linear chromosomes can be recognised by cellular repair mechanisms as double-strand DNA breaks and can be healed by non-homologous-end-joining activities to produce dicentric chromosomes. During cell divisions, particularly during anaphase, dicentrics can break, thus producing naked chromosome tips susceptible to additional unwanted chromosome fusion. Many telomere-building protein complexes are associated with telomeres to ensure their proper capping function. It has been found however, that a number of repair complexes also contribute to telomere stability. RESULTS We used Arabidopsis thaliana to study the possible functions of the DNA repair subunit, NBS1, in telomere homeostasis using knockout nbs1 mutants. The results showed that although NBS1-deficient plants were viable, lacked any sign of developmental aberration and produced fertile seeds through many generations upon self-fertilisation, plants also missing the functional telomerase (double mutants), rapidly, within three generations, displayed severe developmental defects. Cytogenetic inspection of cycling somatic cells revealed a very early onset of massive genome instability. Molecular methods used for examining the length of telomeres in double homozygous mutants detected much faster telomere shortening than in plants deficient in telomerase gene alone. CONCLUSIONS Our findings suggest that NBS1 acts in concert with telomerase and plays a profound role in plant telomere renewal.
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Affiliation(s)
- Lucie Najdekrova
- Department of Plant Developmental Genetics, Institute of Biophysics of the Czech Academy of Sciences, Kralovopolska 135, Brno, 61265, Czech Republic
| | - Jiri Siroky
- Department of Plant Developmental Genetics, Institute of Biophysics of the Czech Academy of Sciences, Kralovopolska 135, Brno, 61265, Czech Republic
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Boltz KA, Leehy K, Song X, Nelson AD, Shippen DE. ATR cooperates with CTC1 and STN1 to maintain telomeres and genome integrity in Arabidopsis. Mol Biol Cell 2012; 23:1558-68. [PMID: 22357613 PMCID: PMC3327312 DOI: 10.1091/mbc.e11-12-1002] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Telomeres protect chromosome ends from DNA damage. CTC1/STN1/TEN1 (CST), a core telomere-capping complex in plant and vertebrates, suppresses an ATR-dependent DNA damage response in Arabidopsis. Protracted ATR inactivation inhibits telomerase, hastening the onset of telomere dysfunction in CST mutants. The CTC1/STN1/TEN1 (CST) complex is an essential constituent of plant and vertebrate telomeres. Here we show that CST and ATR (ataxia telangiectasia mutated [ATM] and Rad3-related) act synergistically to maintain telomere length and genome stability in Arabidopsis. Inactivation of ATR, but not ATM, temporarily rescued severe morphological phenotypes associated with ctc1 or stn1. Unexpectedly, telomere shortening accelerated in plants lacking CST and ATR. In first-generation (G1) ctc1 atr mutants, enhanced telomere attrition was modest, but in G2 ctc1 atr, telomeres shortened precipitously, and this loss coincided with a dramatic decrease in telomerase activity in G2 atr mutants. Zeocin treatment also triggered a reduction in telomerase activity, suggesting that the prolonged absence of ATR leads to a hitherto-unrecognized DNA damage response (DDR). Finally, our data indicate that ATR modulates DDR in CST mutants by limiting chromosome fusions and transcription of DNA repair genes and also by promoting programmed cell death in stem cells. We conclude that the absence of CST in Arabidopsis triggers a multifaceted ATR-dependent response to facilitate maintenance of critically shortened telomeres and eliminate cells with severe telomere dysfunction.
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Affiliation(s)
- Kara A Boltz
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843, USA
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Higgins JD, Ferdous M, Osman K, Franklin FCH. The RecQ helicase AtRECQ4A is required to remove inter-chromosomal telomeric connections that arise during meiotic recombination in Arabidopsis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2011; 65:492-502. [PMID: 21265901 DOI: 10.1111/j.1365-313x.2010.04438.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
RecQ helicases are a conserved group of proteins with a role in the maintenance of genome integrity. In Saccharomyces cerevisiae (budding yeast), meiotic recombination is increased in the absence of the RecQ helicase Sgs1. Here we investigated the potential meiotic role of the Sgs1 homologue AtRECQ4A and the closely related AtRECQ4B. Both proteins have been shown to function during recombination in somatic cells, but so far their meiotic role has not been investigated. Both AtRECQ4A and AtRECQ4B were expressed in reproductive tissues. Although immunolocalization studies showed that AtRECQ4A associates with recombination intermediates, we found no evidence that its loss or that of AtRECQ4B had a significant effect on meiotic cross-overs, suggesting functional redundancy with other RECQ family members. Nevertheless, pollen viability decreased in Atrecq4A, resulting in a reduction in fertility, although this was not the case in Atrecq4B. Cytological analysis revealed chromatin bridges between the telomeres of non-homologous chromosomes in Atrecq4A at metaphase I, in some instances accompanied by chromosome fragmentation at anaphase I. The bridges required telomeric repeats and were dependent on meiotic recombination. Immunolocalization confirmed the association of AtRECQ4A with the telomeres during prophase I, which we propose enables dissolution of recombination-dependent telomeric associations. Thus, this study has identified a hitherto unknown role for a member of the RECQ helicase family during meiosis that contributes to the maintenance of chromosome integrity. As telomere structure is generally conserved, it seems likely that these associations may arise during meiosis in other species, where they must also be removed.
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Affiliation(s)
- James D Higgins
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
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Abstract
Telomeres are essential structures at the ends of eukaryotic chromosomes. Work on their structure and function began almost 70 years ago in plants and flies, continued through the Nobel Prize winning work on yeast and ciliates, and goes on today in many model and non-model organisms. The basic molecular mechanisms of telomeres are highly conserved throughout evolution, and our current understanding of how telomeres function is a conglomeration of insights gained from many different species. This review will compare the current knowledge of telomeres in plants with other organisms, with special focus on the functional length of telomeric DNA, the search for TRF homologs, the family of POT1 proteins, and the recent discovery of members of the CST complex.
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Affiliation(s)
- J Matthew Watson
- Gregor Mendel Institute of Molecular Plant Biology, Austrian Academy of Sciences, Vienna, Austria
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Watson JM, Riha K. Comparative biology of telomeres: where plants stand. FEBS Lett 2010; 584:3752-9. [PMID: 20580356 PMCID: PMC3767043 DOI: 10.1016/j.febslet.2010.06.017] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2010] [Revised: 06/11/2010] [Accepted: 06/14/2010] [Indexed: 01/02/2023]
Abstract
Telomeres are essential structures at the ends of eukaryotic chromosomes. Work on their structure and function began almost 70 years ago in plants and flies, continued through the Nobel Prize winning work on yeast and ciliates, and goes on today in many model and non-model organisms. The basic molecular mechanisms of telomeres are highly conserved throughout evolution, and our current understanding of how telomeres function is a conglomeration of insights gained from many different species. This review will compare the current knowledge of telomeres in plants with other organisms, with special focus on the functional length of telomeric DNA, the search for TRF homologs, the family of POT1 proteins, and the recent discovery of members of the CST complex.
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Affiliation(s)
- J Matthew Watson
- Gregor Mendel Institute of Molecular Plant Biology, Austrian Academy of Sciences, Vienna, Austria
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14
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Cools T, De Veylder L. DNA stress checkpoint control and plant development. CURRENT OPINION IN PLANT BIOLOGY 2009; 12:23-28. [PMID: 19010080 DOI: 10.1016/j.pbi.2008.09.012] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2008] [Revised: 09/15/2008] [Accepted: 09/29/2008] [Indexed: 05/27/2023]
Abstract
Plants are sedentary, and so have unavoidably close contact with agents that target their genome integrity. To sense and react to these threats, plants have evolved DNA stress checkpoint mechanisms that arrest the cell cycle and activate the DNA repair machinery to preserve the genome content. Although the pathways that maintain DNA integrity are largely conserved among eukaryotic organisms, plants put different accents on cell cycle control under DNA stress and might have their own way to cope with it.
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Affiliation(s)
- Toon Cools
- Department of Plant Systems Biology, Flanders Institute for Biotechnology (VIB), Ghent, Belgium
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