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Závodník M, Pavlištová V, Machelová A, Lyčka M, Mozgová I, Caklová K, Dvořáčková M, Fajkus J. KU70 and CAF-1 in Arabidopsis: Divergent roles in rDNA stability and telomere homeostasis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2024; 118:1922-1936. [PMID: 38493352 DOI: 10.1111/tpj.16718] [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: 09/26/2023] [Revised: 02/07/2024] [Accepted: 02/29/2024] [Indexed: 03/18/2024]
Abstract
Deficiency in chromatin assembly factor-1 (CAF-1) in plants through dysfunction of its components, FASCIATA1 and 2 (FAS1, FAS2), leads to the specific and progressive loss of rDNA and telomere repeats in plants. This loss is attributed to defective repair mechanisms for the increased DNA breaks encountered during replication, a consequence of impaired replication-dependent chromatin assembly. In this study, we explore the role of KU70 in these processes. Our findings reveal that, although the rDNA copy number is reduced in ku70 mutants when compared with wild-type plants, it is not markedly affected by diverse KU70 status in fas1 mutants. This is consistent with our previous characterisation of rDNA loss in fas mutants as a consequence part of the single-strand annealing pathway of homology-dependent repair. In stark contrast to rDNA, KU70 dysfunction fully suppresses the loss of telomeres in fas1 plants and converts telomeres to their elongated and heterogeneous state typical for ku70 plants. We conclude that the alternative telomere lengthening pathway, known to be activated in the absence of KU70, overrides progressive telomere loss due to CAF-1 dysfunction.
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Affiliation(s)
- Michal Závodník
- 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, v.v.i., Brno, CZ-61265, Czech Republic
| | - Veronika Pavlištová
- Mendel Centre for Plant Genomics and Proteomics, CEITEC, Masaryk University, Brno, CZ-62500, Czech Republic
- Laboratory of Functional Genomics and Proteomics, NCBR, Faculty of Science, Masaryk University, Brno, CZ-61137, Czech Republic
| | - Adéla Machelová
- Mendel Centre for Plant Genomics and Proteomics, CEITEC, Masaryk University, Brno, CZ-62500, Czech Republic
- Laboratory of Functional Genomics and Proteomics, NCBR, Faculty of Science, Masaryk University, Brno, CZ-61137, Czech Republic
| | - Martin Lyčka
- Mendel Centre for Plant Genomics and Proteomics, CEITEC, Masaryk University, Brno, CZ-62500, Czech Republic
- Laboratory of Functional Genomics and Proteomics, NCBR, Faculty of Science, Masaryk University, Brno, CZ-61137, Czech Republic
| | - Iva Mozgová
- Biology Centre, Czech Academy of Sciences, Institute of Plant Molecular Biology, České Budějovice, Czech Republic
- University of South Bohemia, Faculty of Science, České Budějovice, Czech Republic
| | - Karolína Caklová
- Laboratory of Functional Genomics and Proteomics, NCBR, Faculty of Science, Masaryk University, Brno, CZ-61137, Czech Republic
| | - Martina Dvořáčková
- Mendel Centre for Plant Genomics and Proteomics, CEITEC, Masaryk University, Brno, CZ-62500, Czech Republic
- Laboratory of Functional Genomics and Proteomics, NCBR, Faculty of Science, Masaryk University, Brno, CZ-61137, Czech Republic
| | - Jiří 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, v.v.i., Brno, CZ-61265, Czech Republic
- Laboratory of Functional Genomics and Proteomics, NCBR, Faculty of Science, Masaryk University, Brno, CZ-61137, Czech Republic
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2
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Konečná KP, Kilar A, Kováčiková P, Fajkus J, Sýkorová E, Fojtová M. Compromised function of ARM, the interactor of Arabidopsis telomerase, suggests its role in stress responses. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2022; 325:111453. [PMID: 36087885 DOI: 10.1016/j.plantsci.2022.111453] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Revised: 08/02/2022] [Accepted: 09/03/2022] [Indexed: 06/15/2023]
Abstract
ARM was identified previously as an interaction partner of the telomerase protein subunit (TERT) in Arabidopsis thaliana. To investigate the interconnection between ARM and telomerase and to identify ARM cellular functions, we analyzed a set of arm mutant lines and arm/tert double mutants. Telomere length was not affected in arm single mutant plants, in contrast to double mutants. In the second generation of homozygous arm-1/tert double mutants following the heterozygous state during the double mutant construction, telomeres shortened dramatically, even below levels in tert plants displaying severe morphological defects. Intriguingly, homozygous arm-1/tert double mutants with short telomeres grew without obvious phenotypic changes for next two generations. Then, in agreement with the onset of phenotypic changes in tert, morphological defects were timed to the 5th arm-1/tert homozygous generation. RNAseq analyses of arm-1/tert and respective single mutants displayed markedly overlapping sets of differentially expressed genes in arm-1/tert double mutant and arm-1 single mutant lines, indicating a dominant effect of the ARM mutation. RNAseq data further implied ARM involvement in circadian rhythms, responses to drugs and to biotic and abiotic stimuli. In agreement with it, we observed sensitivity of arm-1 single mutant to the heat stress during germination. Altogether, our results suggest ARM involvement in crucial cellular processes without evidencing its role in the telomerase canonical function.
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Affiliation(s)
- Klára Přikrylová Konečná
- Institute of Biophysics, Czech Academy of Sciences, Brno, Czech Republic; Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology (CEITEC), Masaryk University, Brno, Czech Republic; National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Brno, Czech Republic
| | - Agata Kilar
- Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology (CEITEC), Masaryk University, Brno, Czech Republic; National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Brno, Czech Republic
| | - Petra Kováčiková
- National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Brno, Czech Republic
| | - Jiří Fajkus
- Institute of Biophysics, Czech Academy of Sciences, Brno, Czech Republic; Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology (CEITEC), Masaryk University, Brno, Czech Republic; National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Brno, Czech Republic
| | - Eva Sýkorová
- Institute of Biophysics, Czech Academy of Sciences, Brno, Czech Republic
| | - Miloslava Fojtová
- Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology (CEITEC), Masaryk University, Brno, Czech Republic; National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Brno, Czech Republic.
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3
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Telomerase Interaction Partners-Insight from Plants. Int J Mol Sci 2021; 23:ijms23010368. [PMID: 35008793 PMCID: PMC8745574 DOI: 10.3390/ijms23010368] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Revised: 12/26/2021] [Accepted: 12/27/2021] [Indexed: 12/29/2022] Open
Abstract
Telomerase, an essential enzyme that maintains chromosome ends, is important for genome integrity and organism development. Various hypotheses have been proposed in human, ciliate and yeast systems to explain the coordination of telomerase holoenzyme assembly and the timing of telomerase performance at telomeres during DNA replication or repair. However, a general model is still unclear, especially pathways connecting telomerase with proposed non-telomeric functions. To strengthen our understanding of telomerase function during its intracellular life, we report on interactions of several groups of proteins with the Arabidopsis telomerase protein subunit (AtTERT) and/or a component of telomerase holoenzyme, POT1a protein. Among these are the nucleosome assembly proteins (NAP) and the minichromosome maintenance (MCM) system, which reveal new insights into the telomerase interaction network with links to telomere chromatin assembly and replication. A targeted investigation of 176 candidate proteins demonstrated numerous interactions with nucleolar, transport and ribosomal proteins, as well as molecular chaperones, shedding light on interactions during telomerase biogenesis. We further identified protein domains responsible for binding and analyzed the subcellular localization of these interactions. Moreover, additional interaction networks of NAP proteins and the DOMINO1 protein were identified. Our data support an image of functional telomerase contacts with multiprotein complexes including chromatin remodeling and cell differentiation pathways.
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Eekhout T, Dvorackova M, Pedroza Garcia JA, Nespor Dadejova M, Kalhorzadeh P, Van den Daele H, Vercauteren I, Fajkus J, De Veylder L. G2/M-checkpoint activation in fasciata1 rescues an aberrant S-phase checkpoint but causes genome instability. PLANT PHYSIOLOGY 2021; 186:1893-1907. [PMID: 34618100 PMCID: PMC8331141 DOI: 10.1093/plphys/kiab201] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Accepted: 04/05/2021] [Indexed: 05/13/2023]
Abstract
The WEE1 and ATM AND RAD3-RELATED (ATR) kinases are important regulators of the plant intra-S-phase checkpoint; consequently, WEE1KO and ATRKO roots are hypersensitive to replication-inhibitory drugs. Here, we report on a loss-of-function mutant allele of the FASCIATA1 (FAS1) subunit of the chromatin assembly factor 1 (CAF-1) complex that suppresses the phenotype of WEE1- or ATR-deficient Arabidopsis (Arabidopsis thaliana) plants. We demonstrate that lack of FAS1 activity results in the activation of an ATAXIA TELANGIECTASIA MUTATED (ATM)- and SUPPRESSOR OF GAMMA-RESPONSE 1 (SOG1)-mediated G2/M-arrest that renders the ATR and WEE1 checkpoint regulators redundant. This ATM activation accounts for the telomere erosion and loss of ribosomal DNA that are described for fas1 plants. Knocking out SOG1 in the fas1 wee1 background restores replication stress sensitivity, demonstrating that SOG1 is an important secondary checkpoint regulator in plants that fail to activate the intra-S-phase checkpoint.
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Affiliation(s)
- Thomas Eekhout
- Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Gent, Belgium
- Center for Plant Systems Biology, VIB, 9052 Gent, Belgium
| | - Martina Dvorackova
- Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology, Masaryk University, CZ-62500 Brno, Czech Republic
| | - José Antonio Pedroza Garcia
- Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Gent, Belgium
- Center for Plant Systems Biology, VIB, 9052 Gent, Belgium
| | - Martina Nespor Dadejova
- Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology, Masaryk University, CZ-62500 Brno, Czech Republic
| | - Pooneh Kalhorzadeh
- Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Gent, Belgium
- Center for Plant Systems Biology, VIB, 9052 Gent, Belgium
| | - Hilde Van den Daele
- Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Gent, Belgium
- Center for Plant Systems Biology, VIB, 9052 Gent, Belgium
| | - Ilse Vercauteren
- Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Gent, Belgium
- Center for Plant Systems Biology, VIB, 9052 Gent, Belgium
| | - Jiri Fajkus
- Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology, Masaryk University, CZ-62500 Brno, Czech Republic
| | - Lieven De Veylder
- Department of Plant Biotechnology and Bioinformatics, Ghent University, 9052 Gent, Belgium
- Center for Plant Systems Biology, VIB, 9052 Gent, Belgium
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Nuclear Chaperone ASF1 is Required for Gametogenesis in Arabidopsis thaliana. Sci Rep 2019; 9:13959. [PMID: 31562367 PMCID: PMC6764951 DOI: 10.1038/s41598-019-50450-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2019] [Accepted: 09/11/2019] [Indexed: 12/31/2022] Open
Abstract
Sexual reproduction in flowering plants is distinct from that in animals since gametogenesis requires production of haploid spores, which divide and differentiate into specialised gametophyte structures. Anti-Silencing Function 1 (ASF1) is a histone H3/H4 chaperone involved in chromatin remodeling during cell division, which we have found plays a critical role in gametophyte development in Arabidopsis thaliana. Using mutant alleles for the two ASF1 homologs, asf1a and asf1b, we show that ASF1 is required for successful development of gametophytes and acquisition of fertilisation competency. On the female side, reproductive failure is caused by aberrant development of ovules, leading to gamete degeneration. On the male side, we show both in vitro and in vivo that asf1 mutant pollen tube growth is stunted, limiting fertilisation to ovules nearest the stigma. Consistent with ASF1 importance in gametogenesis, we show that ASF1A and ASF1B are expressed throughout female and male gametogenesis. We show that the gametogenesis defects can be corrected by ASF1A and ASF1B transgenes, and that ASF1A and ASF1B act redundantly. Thus, in contrast to the role of ASF1 in sporophytic cell cycle progression, our data indicate that during reproduction, ASF1 is required for the precise nuclei differentiation necessary for gametophyte maturation and fertilisation.
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Goffová I, Vágnerová R, Peška V, Franek M, Havlová K, Holá M, Zachová D, Fojtová M, Cuming A, Kamisugi Y, Angelis KJ, Fajkus J. Roles of RAD51 and RTEL1 in telomere and rDNA stability in Physcomitrella patens. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2019; 98:1090-1105. [PMID: 30834585 DOI: 10.1111/tpj.14304] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Revised: 02/21/2019] [Accepted: 02/27/2019] [Indexed: 05/11/2023]
Abstract
Telomeres and ribosomal RNA genes (rDNA) are essential for cell survival and particularly sensitive to factors affecting genome stability. Here, we examine the role of RAD51 and its antagonist, RTEL1, in the moss Physcomitrella patens. In corresponding mutants, we analyse their sensitivity to DNA damage, the maintenance of telomeres and rDNA, and repair of double-stranded breaks (DSBs) induced by genotoxins with various modes of action. While the loss of RTEL1 results in rapid telomere shortening, concurrent loss of both RAD51 genes has no effect on telomere lengths. We further demonstrate here the linked arrangement of 5S and 45S rRNA genes in P. patens. The spacer between 5S and 18S rRNA genes, especially the region downstream from the transcription start site, shows conspicuous clustering of sites with a high propensity to form quadruplex (G4) structures. Copy numbers of 5S and 18S rDNA are reduced moderately in the pprtel1 mutant, and significantly in the double pprad51-1-2 mutant, with no progression during subsequent cultivation. While reductions in 45S rDNA copy numbers observed in pprtel1 and pprad51-1-2 plants apply also to 5S rDNA, changes in transcript levels are different for 45S and 5S rRNA, indicating their independent transcription by RNA polymerase I and III, respectively. The loss of SOL (Sog One-Like), a transcription factor regulating numerous genes involved in DSB repair, increases the rate of DSB repair in dividing as well as differentiated tissue, and through deactivation of G2/M cell-cycle checkpoint allows the cell-cycle progression manifested as a phenotype resistant to bleomycin.
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Affiliation(s)
- Ivana Goffová
- Laboratory of Functional Genomics and Proteomics, National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kotlářská 2, CZ-61137, Brno, Czech Republic
- Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology, Masaryk University, Kamenice 5, CZ-62500, Brno, Czech Republic
| | - Radka Vágnerová
- The Czech Academy of Sciences, Institute of Experimental Botany, Na Karlovce 1, CZ-16000, Prague, Czech Republic
| | - Vratislav Peška
- The Czech Academy of Sciences, Institute of Biophysics, Královopolská 135, 612 65, Brno, Czech Republic
| | - Michal Franek
- Laboratory of Functional Genomics and Proteomics, National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kotlářská 2, CZ-61137, Brno, Czech Republic
- Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology, Masaryk University, Kamenice 5, CZ-62500, Brno, Czech Republic
| | - Kateřina Havlová
- Laboratory of Functional Genomics and Proteomics, National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kotlářská 2, CZ-61137, Brno, Czech Republic
- Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology, Masaryk University, Kamenice 5, CZ-62500, Brno, Czech Republic
| | - Marcela Holá
- The Czech Academy of Sciences, Institute of Experimental Botany, Na Karlovce 1, CZ-16000, Prague, Czech Republic
| | - Dagmar Zachová
- Laboratory of Functional Genomics and Proteomics, National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kotlářská 2, CZ-61137, Brno, Czech Republic
- Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology, Masaryk University, Kamenice 5, CZ-62500, Brno, Czech Republic
| | - Miloslava Fojtová
- Laboratory of Functional Genomics and Proteomics, National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kotlářská 2, CZ-61137, Brno, Czech Republic
- Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology, Masaryk University, Kamenice 5, CZ-62500, Brno, Czech Republic
| | - Andrew Cuming
- Centre for Plant Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK
| | - Yasuko Kamisugi
- Centre for Plant Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, LS2 9JT, UK
| | - Karel J Angelis
- The Czech Academy of Sciences, Institute of Experimental Botany, Na Karlovce 1, CZ-16000, Prague, Czech Republic
| | - Jiří Fajkus
- Laboratory of Functional Genomics and Proteomics, National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kotlářská 2, CZ-61137, Brno, Czech Republic
- Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology, Masaryk University, Kamenice 5, CZ-62500, Brno, Czech Republic
- The Czech Academy of Sciences, Institute of Biophysics, Královopolská 135, 612 65, Brno, Czech Republic
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Varas J, Santos JL, Pradillo M. The Absence of the Arabidopsis Chaperone Complex CAF-1 Produces Mitotic Chromosome Abnormalities and Changes in the Expression Profiles of Genes Involved in DNA Repair. FRONTIERS IN PLANT SCIENCE 2017; 8:525. [PMID: 28443118 PMCID: PMC5386969 DOI: 10.3389/fpls.2017.00525] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2016] [Accepted: 03/24/2017] [Indexed: 05/19/2023]
Abstract
Chromatin Assembly Factor 1 (CAF-1) is an evolutionary conserved heterotrimeric chaperone complex that facilitates the incorporation of histones H3 and H4 onto newly synthesized DNA. We demonstrate here that the mutant deficient for the large subunit of the complex, fas1-4, and in minor extent, the mutant deficient for the middle subunit, fas2-1, display chromosome abnormalities throughout Arabidopsis mitosis. Among them, we observed multicentromeric chromosomes at metaphase, and chromatid bridges and acentric fragments at anaphase-telophase. 45S rDNA and telomeric sequences were frequently involved in bridges and fragments. Gene expression analysis by real-time qPCR has revealed that several genes related to homologous recombination (HR) and alternative non-homologous end-joining (aNHEJ) are overexpressed in fas1-4. These results concur with previous studies which have indicated that HR may be involved in the progressive loss of 45S rDNA and telomeres displayed by fas mutants. However, increased expression of PARP1, PARP2, and LIG6 in fas1-4, and the phenotype shown by the double mutant fas1 rad51 suggest that aNHEJ should also be responsible for the chromosomal aberrations observed. The activity of different DNA repair pathways in absence of CAF-1 is discussed.
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8
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Pavlištová V, Dvořáčková M, Jež M, Mozgová I, Mokroš P, Fajkus J. Phenotypic reversion in fas mutants of Arabidopsis thaliana by reintroduction of FAS genes: variable recovery of telomeres with major spatial rearrangements and transcriptional reprogramming of 45S rDNA genes. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2016; 88:411-424. [PMID: 27377564 DOI: 10.1111/tpj.13257] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2016] [Revised: 06/23/2016] [Accepted: 06/27/2016] [Indexed: 05/28/2023]
Abstract
Arabidopsis thaliana mutants dysfunctional in the evolutionarily conserved protein complex chromatin assembly factor-1 (CAF-1), which deposits the canonical histone H3 variant H3.1 during DNA synthesis-dependent chromatin assembly, display complex phenotypic changes including meristem and growth alterations, sensitivity to DNA-damaging agents, and reduced fertility. We reported previously that mutants in the FAS1 subunit of CAF-1 progressively lose telomere and 45S rDNA repeats. Here we show that multiple aspects of the fas phenotype are recovered immediately on expression of a reintroduced FAS1 allele, and are clearly independent of the recovery of rDNA copy-numbers and telomeres. In reverted lines, 45S rDNA genes are recovered to diverse levels with a strikingly different representation of their variants, and the typical association of nucleolar organizing region 4 with the nucleolus is perturbed. One of 45S rDNA variants (VAR1), which is silenced in wild-type (WT) plants without mutation history (Col-0 WT), dominates the expression pattern, whereas VAR2 is dominant in Col-0 WT plants. We propose an explanation for the variability of telomere and 45S rDNA repeats associated with CAF-1 function, suggesting that the differences in nuclear partitioning and expression of the rDNA variants in fas mutants and their revertants provide a useful experimental system to study genetic and epigenetic factors in gene dosage compensation.
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Affiliation(s)
- Veronika Pavlištová
- Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology - CEITEC, Masaryk University, Brno, Czech Republic
- Laboratory of Functional Genomics and Proteomics, NCBR, Faculty of Science, Masaryk University, Brno, Czech Republic
| | - Martina Dvořáčková
- Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology - CEITEC, Masaryk University, Brno, Czech Republic
- Institute of Biophysics, Czech Academy of Sciences, Brno, Czech Republic
| | - Michal Jež
- Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology - CEITEC, Masaryk University, Brno, Czech Republic
- Laboratory of Functional Genomics and Proteomics, NCBR, Faculty of Science, Masaryk University, Brno, Czech Republic
| | - Iva Mozgová
- Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology - CEITEC, Masaryk University, Brno, Czech Republic
- Laboratory of Functional Genomics and Proteomics, NCBR, Faculty of Science, Masaryk University, Brno, Czech Republic
| | - Petr Mokroš
- Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology - CEITEC, Masaryk University, Brno, Czech Republic
| | - Jiří Fajkus
- Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology - CEITEC, Masaryk University, Brno, Czech Republic
- Laboratory of Functional Genomics and Proteomics, NCBR, Faculty of Science, Masaryk University, Brno, Czech Republic
- Institute of Biophysics, Czech Academy of Sciences, Brno, Czech Republic
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9
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Maksimov V, Nakamura M, Wildhaber T, Nanni P, Ramström M, Bergquist J, Hennig L. The H3 chaperone function of NASP is conserved in Arabidopsis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2016; 88:425-436. [PMID: 27402088 DOI: 10.1111/tpj.13263] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Revised: 06/20/2016] [Accepted: 06/22/2016] [Indexed: 06/06/2023]
Abstract
Histones are abundant cellular proteins but, if not incorporated into chromatin, they are usually bound by histone chaperones. Here, we identify Arabidopsis NASP as a chaperone for histones H3.1 and H3.3. NASP interacts in vitro with monomeric H3.1 and H3.3 as well as with histone H3.1-H4 and H3.3-H4 dimers. However, NASP does not bind to monomeric H4. NASP shifts the equilibrium between histone dimers and tetramers towards tetramers but does not interact with tetramers in vitro. Arabidopsis NASP promotes [H3-H4]2 tetrasome formation, possibly by providing preassembled histone tetramers. However, NASP does not promote disassembly of in vitro preassembled tetrasomes. In contrast to its mammalian homolog, Arabidopsis NASP is a predominantly nuclear protein. In vivo, NASP binds mainly monomeric H3.1 and H3.3. Pulldown experiments indicated that NASP may also interact with the histone chaperone MSI1 and a HSC70 heat shock protein.
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Affiliation(s)
- Vladimir Maksimov
- Department of Plant Biology and Linnean Center for Plant Biology, Swedish University of Agricultural Sciences, PO-Box 7080, SE-75007, Uppsala, Sweden
| | - Miyuki Nakamura
- Department of Plant Biology and Linnean Center for Plant Biology, Swedish University of Agricultural Sciences, PO-Box 7080, SE-75007, Uppsala, Sweden
| | - Thomas Wildhaber
- Department of Biology and Zurich-Basel Plant Science Center, ETH Zurich, CH-8092, Zurich, Switzerland
| | - Paolo Nanni
- Functional Genomics Center Zurich, University of Zurich/ETH Zurich, CH-8057, Zurich, Switzerland
| | - Margareta Ramström
- Department of Chemistry-BMC, Analytical Chemistry and Science for Life Laboratory, Uppsala University, SE-75124, Uppsala, Sweden
| | - Jonas Bergquist
- Department of Chemistry-BMC, Analytical Chemistry and Science for Life Laboratory, Uppsala University, SE-75124, Uppsala, Sweden
| | - Lars Hennig
- Department of Plant Biology and Linnean Center for Plant Biology, Swedish University of Agricultural Sciences, PO-Box 7080, SE-75007, Uppsala, Sweden
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10
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Dvořáčková M, Fojtová M, Fajkus J. Chromatin dynamics of plant telomeres and ribosomal genes. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2015; 83:18-37. [PMID: 25752316 DOI: 10.1111/tpj.12822] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Revised: 03/03/2015] [Accepted: 03/03/2015] [Indexed: 05/03/2023]
Abstract
Telomeres and genes encoding 45S ribosomal RNA (rDNA) are frequently located adjacent to each other on eukaryotic chromosomes. Although their primary roles are different, they show striking similarities with respect to their features and additional functions. Both genome domains have remarkably dynamic chromatin structures. Both are hypersensitive to dysfunctional histone chaperones, responding at the genomic and epigenomic levels. Both generate non-coding transcripts that, in addition to their epigenetic roles, may induce gross chromosomal rearrangements. Both give rise to chromosomal fragile sites, as their replication is intrinsically problematic. However, at the same time, both are essential for maintenance of genomic stability and integrity. Here we discuss the structural and functional inter-connectivity of telomeres and rDNA, with a focus on recent results obtained in plants.
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Affiliation(s)
- Martina Dvořáčková
- Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology, Kamenice 5, 62500, Brno, Czech Republic
- Faculty of Science, Masaryk University, Kamenice 5, 62500, Brno, Czech Republic
- Institute of Biophysics, Academy of Sciences of the Czech Republic, Královopolská 135, 61265, Brno, Czech Republic
| | - Miloslava Fojtová
- Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology, Kamenice 5, 62500, Brno, Czech Republic
- Faculty of Science, Masaryk University, Kamenice 5, 62500, Brno, Czech Republic
- Institute of Biophysics, Academy of Sciences of the Czech Republic, Královopolská 135, 61265, Brno, Czech Republic
| | - Jiří Fajkus
- Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology, Kamenice 5, 62500, Brno, Czech Republic
- Faculty of Science, Masaryk University, Kamenice 5, 62500, Brno, Czech Republic
- Institute of Biophysics, Academy of Sciences of the Czech Republic, Královopolská 135, 61265, Brno, Czech Republic
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11
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Fojtová M, Sýkorová E, Najdekrová L, Polanská P, Zachová D, Vagnerová R, Angelis KJ, Fajkus J. Telomere dynamics in the lower plant Physcomitrella patens. PLANT MOLECULAR BIOLOGY 2015; 87:591-601. [PMID: 25701469 DOI: 10.1007/s11103-015-0299-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2015] [Accepted: 02/16/2015] [Indexed: 06/04/2023]
Abstract
A comparative approach in biology is needed to assess the universality of rules governing this discipline. In plant telomere research, most of the key principles were established based on studies in only single model plant, Arabidopsis thaliana. These principles include the absence of telomere shortening during plant development and the corresponding activity of telomerase in dividing (meristem) plant cells. Here we examine these principles in Physcomitrella patens as a representative of lower plants. To follow telomerase expression, we first characterize the gene coding for the telomerase reverse transcriptase subunit PpTERT in P. patens, for which only incomplete prediction has been available so far. In protonema cultures of P. patens, growing by filament apical cell division, the proportion of apical (dividing) cells was quantified and telomere length, telomerase expression and activity were determined. Our results show telomere stability and demonstrate proportionality of telomerase activity and expression with the number of apical cells. In addition, we analyze telomere maintenance in mre11, rad50, nbs1, ku70 and lig4 mutants of P. patens and compare the impact of these mutations in double-strand-break (DSB) repair pathways with earlier observations in corresponding A. thaliana mutants. Telomere phenotypes are absent and DSB repair kinetics is not affected in P. patens mutants for DSB factors involved in non-homologous end joining (NHEJ). This is compliant with the overall dominance of homologous recombination over NHEJ pathways in the moss, contrary to the inverse situation in flowering plants.
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Affiliation(s)
- Miloslava Fojtová
- Faculty of Science and CEITEC - Central European Institute of Technology, Masaryk University, Kamenice 5, 62500, Brno, Czech Republic
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12
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Muchová V, Amiard S, Mozgová I, Dvořáčková M, Gallego ME, White C, Fajkus J. Homology-dependent repair is involved in 45S rDNA loss in plant CAF-1 mutants. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2015; 81:198-209. [PMID: 25359579 PMCID: PMC4309414 DOI: 10.1111/tpj.12718] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Revised: 10/23/2014] [Accepted: 10/24/2014] [Indexed: 05/19/2023]
Abstract
Arabidopsis thaliana mutants in FAS1 and FAS2 subunits of chromatin assembly factor 1 (CAF1) show progressive loss of 45S rDNA copies and telomeres. We hypothesized that homology-dependent DNA damage repair (HDR) may contribute to the loss of these repeats in fas mutants. To test this, we generated double mutants by crossing fas mutants with knock-out mutants in RAD51B, one of the Rad51 paralogs of A. thaliana. Our results show that the absence of RAD51B decreases the rate of rDNA loss, confirming the implication of RAD51B-dependent recombination in rDNA loss in the CAF1 mutants. Interestingly, this effect is not observed for telomeric repeat loss, which thus differs from that acting in rDNA loss. Involvement of DNA damage repair in rDNA dynamics in fas mutants is further supported by accumulation of double-stranded breaks (measured as γ-H2AX foci) in 45S rDNA. Occurrence of the foci is not specific for S-phase, and is ATM-independent. While the foci in fas mutants occur both in the transcribed (intranucleolar) and non-transcribed (nucleoplasmic) fraction of rDNA, double fas rad51b mutants show a specific increase in the number of the intranucleolar foci. These results suggest that the repair of double-stranded breaks present in the transcribed rDNA region is RAD51B dependent and that this contributes to rDNA repeat loss in fas mutants, presumably via the single-stranded annealing recombination pathway. Our results also highlight the importance of proper chromatin assembly in the maintenance of genome stability.
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Affiliation(s)
- Veronika Muchová
- Mendel Centre for Plant Genomics and Proteomics, CEITEC, Masaryk University, Kamenice 5, CZ-62500, Brno, Czech Republic; Laboratory of Functional Genomics and Proteomics, National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kotlářská 2, CZ-61137, Brno, Czech Republic
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13
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Otero S, Desvoyes B, Gutierrez C. Histone H3 dynamics in plant cell cycle and development. Cytogenet Genome Res 2014; 143:114-24. [PMID: 25060842 DOI: 10.1159/000365264] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Chromatin is a macromolecular complex where DNA associates with histone proteins and a variety of non-histone proteins. Among the 4 histone types present in nucleosomes, histone H3 is encoded by a large number of genes in most eukaryotic species and is the histone that contains the largest variety of potential post-translational modifications in the N-terminal amino acid residues. In addition to centromeric histone H3, 2 major types of histone H3 exist, namely the canonical H3.1 and the variant H3.3. In this article, we review the most recent observations on the distinctive features of plant H3 proteins in terms of their expression and dynamics during the cell cycle and at various developmental stages. We also include a discussion on the histone H3 chaperones that actively participate in H3 deposition, in particular CAF-1, HIRA and ASF1, and on the putative plant homologs of human ATRX and DEK chaperones. Accumulating evidence confirms that the balanced deposition of H3.1 and H3.3 is of primary relevance for cell differentiation during plant organogenesis.
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Affiliation(s)
- Sofía Otero
- Department of Genome Dynamics and Function, Centro de Biologia Molecular Severo Ochoa, CSIC-UAM, Madrid, Spain
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14
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Fojtová M, Fajkus J. Epigenetic Regulation of Telomere Maintenance. Cytogenet Genome Res 2014; 143:125-35. [DOI: 10.1159/000360775] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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15
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Desvoyes B, Fernández-Marcos M, Sequeira-Mendes J, Otero S, Vergara Z, Gutierrez C. Looking at plant cell cycle from the chromatin window. FRONTIERS IN PLANT SCIENCE 2014; 5:369. [PMID: 25120553 PMCID: PMC4110626 DOI: 10.3389/fpls.2014.00369] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2014] [Accepted: 07/11/2014] [Indexed: 05/03/2023]
Abstract
The cell cycle is defined by a series of complex events, finely coordinated through hormonal, developmental and environmental signals, which occur in a unidirectional manner and end up in producing two daughter cells. Accumulating evidence reveals that chromatin is not a static entity throughout the cell cycle. In fact, there are many changes that include nucleosome remodeling, histone modifications, deposition and exchange, among others. Interestingly, it is possible to correlate the occurrence of several of these chromatin-related events with specific processes necessary for cell cycle progression, e.g., licensing of DNA replication origins, the E2F-dependent transcriptional wave in G1, the activation of replication origins in S-phase, the G2-specific transcription of genes required for mitosis or the chromatin packaging occurring in mitosis. Therefore, an emerging view is that chromatin dynamics must be considered as an intrinsic part of cell cycle regulation. In this article, we review the main features of several key chromatin events that occur at defined times throughout the cell cycle and discuss whether they are actually controlling the transit through specific cell cycle stages.
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Affiliation(s)
| | | | | | | | | | - Crisanto Gutierrez
- *Correspondence: Crisanto Gutierrez, Centro de Biologia Molecular Severo Ochoa, Consejo Superior de Investigaciones Cientificas, Universidad Autónoma de Madrid, Nicolas Cabrera 1, Cantoblanco, Madrid 28049, Spain e-mail:
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16
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Ogrocká A, Polanská P, Majerová E, Janeba Z, Fajkus J, Fojtová M. Compromised telomere maintenance in hypomethylated Arabidopsis thaliana plants. Nucleic Acids Res 2013; 42:2919-31. [PMID: 24334955 PMCID: PMC3950684 DOI: 10.1093/nar/gkt1285] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Telomeres, nucleoprotein structures at the ends of linear eukaryotic chromosomes, are important for the maintenance of genomic stability. Telomeres were considered as typical heterochromatic regions, but in light of recent results, this view should be reconsidered. Asymmetrically located cytosines in plant telomeric DNA repeats may be substrates for a DNA methyltransferase enzyme and indeed, it was shown that these repeats are methylated. Here, we analyse the methylation of telomeric cytosines and the length of telomeres in Arabidopsis thaliana methylation mutants (met 1-3 and ddm 1-8), and in their wild-type siblings that were germinated in the presence of hypomethylation drugs. Our results show that cytosine methylation in telomeric repeats depends on the activity of MET1 and DDM1 enzymes. Significantly shortened telomeres occur in later generations of methylation mutants as well as in plants germinated in the presence of hypomethylation drugs, and this phenotype is stably transmitted to the next plant generation. A possible role of compromised in vivo telomerase action in the observed telomere shortening is hypothesized based on telomere analysis of hypomethylated telomerase knockout plants. Results are discussed in connection with previous data in this field obtained using different model systems.
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Affiliation(s)
- Anna Ogrocká
- Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology (CEITEC), Masaryk University, Kamenice 5, 62500 Brno, Czech Republic, Functional Genomics and Proteomics, National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Kotlářská 2, 611 37 Brno, Czech Republic, Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic v.v.i., Flemingovo nám. 2, 166 10, Prague, Czech Republic and Institute of Biophysics, Academy of Sciences of the Czech Republic v.v.i., Královopolská 135, 612 65 Brno, Czech Republic
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