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Bose S, Suescún AV, Song J, Castillo-González C, Aklilu BB, Branham E, Lynch R, Shippen DE. tRNA ADENOSINE DEAMINASE 3 is required for telomere maintenance in Arabidopsis thaliana. PLANT CELL REPORTS 2020; 39:1669-1685. [PMID: 32959123 PMCID: PMC7655638 DOI: 10.1007/s00299-020-02594-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Accepted: 09/04/2020] [Indexed: 05/05/2023]
Abstract
KEY MESSAGE: tRNA Adenosine Deaminase 3 helps to sustain telomere tracts in a telomerase-independent fashion, likely through regulating cellular metabolism. Telomere length maintenance is influenced by a complex web of chromatin and metabolism-related factors. We previously reported that a lncRNA termed AtTER2 regulates telomerase activity in Arabidopsis thaliana in response to DNA damage. AtTER2 was initially shown to partially overlap with the 5' UTR of the tRNA ADENOSINE DEAMINASE 3 (TAD3) gene. However, updated genome annotation showed that AtTER2 was completely embedded in TAD3, raising the possibility that phenotypes ascribed to AtTER2 could be derived from TAD3. Here we show through strand-specific RNA-Seq, strand-specific qRT-PCR and bioinformatic analyses that AtTER2 does not encode a stable lncRNA. Further examination of the original tad3 (ter2-1/tad3-1) mutant revealed expression of an antisense transcript driven by a cryptic promoter in the T-DNA. Hence, a new hypomorphic allele of TAD3 (tad3-2) was examined. tad3-2 mutants showed hypersensitivity to DNA damage, but no deregulation of telomerase, suggesting that the telomerase phenotype of tad3-1 mutants reflects an off-target effect. Unexpectedly, however, tad3-2 plants displayed progressive loss of telomeric DNA over successive generations that was not accompanied by alteration of terminal architecture or end protection. The phenotype was exacerbated in plants lacking the telomerase processivity factor POT1a, indicating that TAD3 promotes telomere maintenance through a non-canonical, telomerase-independent pathway. The transcriptome of tad3-2 mutants revealed significant dysregulation of genes involved in auxin signaling and glucosinolate biosynthesis, pathways that intersect the stress response, cell cycle regulation and DNA metabolism. These findings indicate that the TAD3 locus indirectly contributes to telomere length homeostasis by altering the metabolic profile in Arabidopsis.
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Affiliation(s)
- Sreyashree Bose
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX, USA
| | - Ana Victoria Suescún
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX, USA
- Facultad de Ciencias, Instituto de Ciencias Ambientales Y Evolutivas, Universidad Austral de Chile, Valdivia, Chile
| | - Jiarui Song
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX, USA
| | | | - Behailu Birhanu Aklilu
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX, USA
- KWS Gateway Research Center, LLC, 1005 N Warson Rd, BRDG Park, St. Louis, MO, 63132, USA
| | - Erica Branham
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX, USA
| | - Ryan Lynch
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX, USA
| | - Dorothy E Shippen
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX, USA.
- Department of Biochemistry and Biophysics, 300 Olsen Blvd, Room 413, College Station, TX, 77843-2128, USA.
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2
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Schrumpfová PP, Fajkus J. Composition and Function of Telomerase-A Polymerase Associated with the Origin of Eukaryotes. Biomolecules 2020; 10:biom10101425. [PMID: 33050064 PMCID: PMC7658794 DOI: 10.3390/biom10101425] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Revised: 09/29/2020] [Accepted: 10/01/2020] [Indexed: 12/19/2022] Open
Abstract
The canonical DNA polymerases involved in the replication of the genome are unable to fully replicate the physical ends of linear chromosomes, called telomeres. Chromosomal termini thus become shortened in each cell cycle. The maintenance of telomeres requires telomerase—a specific RNA-dependent DNA polymerase enzyme complex that carries its own RNA template and adds telomeric repeats to the ends of chromosomes using a reverse transcription mechanism. Both core subunits of telomerase—its catalytic telomerase reverse transcriptase (TERT) subunit and telomerase RNA (TR) component—were identified in quick succession in Tetrahymena more than 30 years ago. Since then, both telomerase subunits have been described in various organisms including yeasts, mammals, birds, reptiles and fish. Despite the fact that telomerase activity in plants was described 25 years ago and the TERT subunit four years later, a genuine plant TR has only recently been identified by our group. In this review, we focus on the structure, composition and function of telomerases. In addition, we discuss the origin and phylogenetic divergence of this unique RNA-dependent DNA polymerase as a witness of early eukaryotic evolution. Specifically, we discuss the latest information regarding the recently discovered TR component in plants, its conservation and its structural features.
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Affiliation(s)
- Petra Procházková Schrumpfová
- 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
- Correspondence:
| | - 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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3
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De la Torre-Espinosa ZY, Barredo-Pool F, Castaño de la Serna E, Sánchez-Teyer LF. Active telomerase during leaf growth and increase of age in plants from Agave tequilana var. Azul. PHYSIOLOGY AND MOLECULAR BIOLOGY OF PLANTS : AN INTERNATIONAL JOURNAL OF FUNCTIONAL PLANT BIOLOGY 2020; 26:639-647. [PMID: 32255928 PMCID: PMC7113356 DOI: 10.1007/s12298-020-00781-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2019] [Revised: 01/28/2020] [Accepted: 02/19/2020] [Indexed: 06/11/2023]
Abstract
In plants, previous studies show that telomerase activity contributes to the maintenance of telomeric length for the proper development of organs and tissues. In this work, we investigated telomerase activity in A. tequilana during several years of cultivation. We found that during growth of the leaf there are two crucial phases: (1) the onset of cell elongation in 3 years and (2) differentiation of vascular bundles in 6 years. This coincides with the ages where the highest telomerase activity is seen. Therefore indicates that telomerase is associated with cellular activities such as; elongation, division, and cell differentiation. Likewise, we detected high activity during the period of vegetative growth, indicating that telomerase also contributes to telomeric maintenance on the leaf in A. tequilana.
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Affiliation(s)
- Zamaria Yoselin De la Torre-Espinosa
- Unidad de Bioquímica y Biología Molecular de Plantas, Centro de Investigación Científica de Yucatán, A.C. Calle 43 No. 130, Colonia Chuburná de Hidalgo, Mérida, Yucatan Mexico
- Unidad de Biotecnología, Centro de Investigación Científica de Yucatán, A.C. Calle 43 No. 130, Colonia Chuburná de Hidalgo, Mérida, Yucatan Mexico
| | - Felipe Barredo-Pool
- Unidad de Biotecnología, Centro de Investigación Científica de Yucatán, A.C. Calle 43 No. 130, Colonia Chuburná de Hidalgo, Mérida, Yucatan Mexico
| | - Enrique Castaño de la Serna
- Unidad de Bioquímica y Biología Molecular de Plantas, Centro de Investigación Científica de Yucatán, A.C. Calle 43 No. 130, Colonia Chuburná de Hidalgo, Mérida, Yucatan Mexico
| | - Lorenzo Felipe Sánchez-Teyer
- Unidad de Biotecnología, Centro de Investigación Científica de Yucatán, A.C. Calle 43 No. 130, Colonia Chuburná de Hidalgo, Mérida, Yucatan Mexico
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4
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Kalinina NO, Makarova S, Makhotenko A, Love AJ, Taliansky M. The Multiple Functions of the Nucleolus in Plant Development, Disease and Stress Responses. FRONTIERS IN PLANT SCIENCE 2018; 9:132. [PMID: 29479362 PMCID: PMC5811523 DOI: 10.3389/fpls.2018.00132] [Citation(s) in RCA: 71] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2017] [Accepted: 01/23/2018] [Indexed: 05/18/2023]
Abstract
The nucleolus is the most conspicuous domain in the eukaryotic cell nucleus, whose main function is ribosomal RNA (rRNA) synthesis and ribosome biogenesis. However, there is growing evidence that the nucleolus is also implicated in many other aspects of cell biology, such as regulation of cell cycle, growth and development, senescence, telomerase activity, gene silencing, responses to biotic and abiotic stresses. In the first part of the review, we briefly assess the traditional roles of the plant nucleolus in rRNA synthesis and ribosome biogenesis as well as possible functions in other RNA regulatory pathways such as splicing, nonsense-mediated mRNA decay and RNA silencing. In the second part of the review we summarize recent progress and discuss already known and new hypothetical roles of the nucleolus in plant growth and development. In addition, this part will highlight studies showing new nucleolar functions involved in responses to pathogen attack and abiotic stress. Cross-talk between the nucleolus and Cajal bodies is also discussed in the context of their association with poly(ADP ribose)polymerase (PARP), which is known to play a crucial role in various physiological processes including growth, development and responses to biotic and abiotic stresses.
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Affiliation(s)
- Natalia O. Kalinina
- Branch of the Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry of the Russian Academy of Sciences, Moscow, Russia
- Natalia O. Kalinina
| | - Svetlana Makarova
- Branch of the Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry of the Russian Academy of Sciences, Moscow, Russia
| | - Antonida Makhotenko
- Branch of the Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry of the Russian Academy of Sciences, Moscow, Russia
| | | | - Michael Taliansky
- Branch of the Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry of the Russian Academy of Sciences, Moscow, Russia
- The James Hutton Institute, Dundee, United Kingdom
- *Correspondence: Michael Taliansky
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5
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Feng G, Burleigh JG, Braun EL, Mei W, Barbazuk WB. Evolution of the 3R-MYB Gene Family in Plants. Genome Biol Evol 2017; 9:1013-1029. [PMID: 28444194 PMCID: PMC5405339 DOI: 10.1093/gbe/evx056] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/20/2017] [Indexed: 12/13/2022] Open
Abstract
Plant 3R-MYB transcription factors are an important subgroup of the MYB super family in plants; however, their evolutionary history and functions remain poorly understood. We identified 225 3R-MYB proteins from 65 plant species, including algae and all major lineages of land plants. Two segmental duplication events preceding the common ancestor of angiosperms have given rise to three subgroups of the 3R-MYB proteins. Five conserved introns in the domain region of the 3R-MYB genes were identified, which arose through a step-wise pattern of intron gain during plant evolution. Alternative splicing (AS) analysis of selected species revealed that transcripts from more than 60% of 3R-MYB genes undergo AS. AS could regulate transcriptional activity for some of the plant 3R-MYBs by generating different regulatory motifs. The 3R-MYB genes of all subgroups appear to be enriched for Mitosis-Specific Activator element core sequences within their upstream promoter region, which suggests a functional involvement in cell cycle. Notably, expression of 3R-MYB genes from different species exhibits differential regulation under various abiotic stresses. These data suggest that the plant 3R-MYBs function in both cell cycle regulation and abiotic stress response, which may contribute to the adaptation of plants to a sessile lifestyle.
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Affiliation(s)
- Guanqiao Feng
- Plant Molecular and Cellular Biology Program, University of Florida, Gainesville, FL
| | - John Gordon Burleigh
- Plant Molecular and Cellular Biology Program, University of Florida, Gainesville, FL.,Department of Biology, University of Florida, Gainesville, FL.,Genetics Institute, University of Florida, Gainesville, FL
| | - Edward L Braun
- Department of Biology, University of Florida, Gainesville, FL.,Genetics Institute, University of Florida, Gainesville, FL
| | - Wenbin Mei
- Department of Biology, University of Florida, Gainesville, FL
| | - William Bradley Barbazuk
- Plant Molecular and Cellular Biology Program, University of Florida, Gainesville, FL.,Department of Biology, University of Florida, Gainesville, FL.,Genetics Institute, University of Florida, Gainesville, FL
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6
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Jurečková JF, Sýkorová E, Hafidh S, Honys D, Fajkus J, Fojtová M. Tissue-specific expression of telomerase reverse transcriptase gene variants in Nicotiana tabacum. PLANTA 2017; 245:549-561. [PMID: 27900472 DOI: 10.1007/s00425-016-2624-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Accepted: 11/23/2016] [Indexed: 06/06/2023]
Abstract
MAIN CONCLUSION In tobacco, three sequence variants of the TERT gene have been described. We revealed unbalanced levels of TERT variant transcripts in vegetative tobacco tissues and enhanced TERT transcription and telomerase activity in reproductive tissues. Telomerase is a ribonucleoprotein complex responsible for the maintenance of telomeres, structures delimiting ends of linear eukaryotic chromosomes. In the Nicotiana tabacum (tobacco) allotetraploid plant, three sequence variants (paralogs) of the gene coding for the telomerase reverse transcriptase subunit (TERT) have been described, two of them derived from the maternal N. sylvestris genome (TERT_Cs, TERT_D) and one originated from the N. tomentosiformis paternal genome (TERT_Ct). In this work, we analyzed the transcription of TERT variants in correlation with telomerase activity in tobacco tissues. High and approximately comparable levels of TERT_Ct and TERT_Cs transcripts were detected in seedlings, roots, flower buds and leaves, while the transcript of the TERT_D variant was markedly underrepresented. Similarly, in N. sylvestris tissues, TERT_Cs transcript significantly predominated. A specific pattern of TERT transcripts was found in samples of tobacco pollen with the TERT_Cs variant clearly dominating particularly at the early stage of pollen development. Detailed analysis of TERT_C variants representation in functionally distinct fractions of pollen transcriptome revealed their prevalence in large ribonucleoprotein particles encompassing translationally silent mRNA; only a minority of TERT_Ct and TERT_Cs transcripts were localized in actively translated polysomes. Histones of the TERT_C chromatin were decorated predominantly with the euchromatin-specific epigenetic modification in both telomerase-positive and telomerase-negative tobacco tissues. We conclude that the existence and transcription pattern of tobacco TERT paralogs represents an interesting phenomenon and our results indicate its functional significance. Nicotiana species have again proved to be appropriate and useful model plants in telomere biology studies.
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Affiliation(s)
- Jana Fišerová Jurečková
- Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology (CEITEC) and Faculty of Science, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic
| | - Eva Sýkorová
- Institute of Biophysics, Academy of Sciences of the Czech Republic v.v.i., Královopolská 135, 612 65, Brno, Czech Republic
| | - Said Hafidh
- Institute of Experimental Botany, Academy of Sciences of the Czech Republic v.v.i., Rozvojová 263, 165 02, Prague, Czech Republic
| | - David Honys
- Institute of Experimental Botany, Academy of Sciences of the Czech Republic v.v.i., Rozvojová 263, 165 02, Prague, Czech Republic
| | - Jiří Fajkus
- Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology (CEITEC) and 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, 612 65, Brno, Czech Republic
| | - Miloslava Fojtová
- Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology (CEITEC) and Faculty of Science, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic.
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7
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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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8
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Zachová D, Fojtová M, Dvořáčková M, Mozgová I, Lermontova I, Peška V, Schubert I, Fajkus J, Sýkorová E. Structure-function relationships during transgenic telomerase expression in Arabidopsis. PHYSIOLOGIA PLANTARUM 2013; 149:114-26. [PMID: 23278240 DOI: 10.1111/ppl.12021] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2012] [Revised: 12/13/2012] [Accepted: 12/14/2012] [Indexed: 05/11/2023]
Abstract
Although telomerase (EC 2.7.7.49) is important for genome stability and totipotency of plant cells, the principles of its regulation are not well understood. Therefore, we studied subcellular localization and function of the full-length and truncated variants of the catalytic subunit of Arabidopsis thaliana telomerase, AtTERT, in planta. Our results show that multiple sites in AtTERT may serve as nuclear localization signals, as all the studied individual domains of the AtTERT were targeted to the nucleus and/or the nucleolus. Although the introduced genomic or cDNA AtTERT transgenes display expression at transcript and protein levels, they are not able to fully complement the lack of telomerase functions in tert -/- mutants. The failure to reconstitute telomerase function in planta suggests a more complex telomerase regulation in plant cells than would be expected based on results of similar experiments in mammalian model systems.
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Affiliation(s)
- Dagmar Zachová
- Faculty of Science and Central European Institute of Technology, Masaryk University, CZ-61137, Brno, Czech Republic
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9
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Lee YW, Kim WT. Telomerase-dependent 3' G-strand overhang maintenance facilitates GTBP1-mediated telomere protection from misplaced homologous recombination. THE PLANT CELL 2013; 25:1329-42. [PMID: 23572544 PMCID: PMC3663271 DOI: 10.1105/tpc.112.107573] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2012] [Revised: 02/17/2013] [Accepted: 03/26/2013] [Indexed: 05/09/2023]
Abstract
At the 3'-end of telomeres, single-stranded G-overhang telomeric repeats form a stable T-loop. Many studies have focused on the mechanisms that generate and regulate the length of telomere 3' G-strand overhangs, but the roles of G-strand overhang length control in proper T-loop formation and end protection remain unclear. Here, we examined functional relationships between the single-stranded telomere binding protein GTBP1 and G-strand overhang lengths maintained by telomerase in tobacco (Nicotiana tabacum). In tobacco plants, telomerase reverse transcriptase subunit (TERT) repression severely worsened the GTBP1 knockdown phenotypes, which were formally characterized as an outcome of telomere destabilization. TERT downregulation shortened the telomere 3' G-overhangs and increased telomere recombinational aberrations in GTBP1-suppressed plants. Correlatively, GTBP1-mediated inhibition of single-strand invasion into the double-strand telomeric sequences was impaired due to shorter single-stranded telomeres. Moreover, TERT/GTBP1 double knockdown amplified misplaced homologous recombination of G-strand overhangs into intertelomeric regions. Thus, proper G-overhang length maintenance is required to protect telomeres against intertelomeric recombination, which is achieved by the balanced functions of GTBP1 and telomerase activity.
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Affiliation(s)
- Yong Woo Lee
- Department of Systems Biology, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Korea
| | - Woo Taek Kim
- Department of Systems Biology, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Korea
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10
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de Almeida M, de Almeida CV, Mendes Graner E, Ebling Brondani G, Fiori de Abreu-Tarazi M. Pre-procambial cells are niches for pluripotent and totipotent stem-like cells for organogenesis and somatic embryogenesis in the peach palm: a histological study. PLANT CELL REPORTS 2012; 31:1495-515. [PMID: 22534682 DOI: 10.1007/s00299-012-1264-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2012] [Revised: 03/26/2012] [Accepted: 04/10/2012] [Indexed: 05/18/2023]
Abstract
UNLABELLED The direct induction of adventitious buds and somatic embryos from explants is a morphogenetic process that is under the influence of exogenous plant growth regulators and its interactions with endogenous phytohormones. We performed an in vitro histological analysis in peach palm (Bactris gasipaes Kunth) shoot apexes and determined that the positioning of competent cells and their interaction with neighboring cells, under the influence of combinations of exogenously applied growth regulators (NAA/BAP and NAA/TDZ), allows the pre-procambial cells (PPCs) to act in different morphogenic pathways to establish niche competent cells. It is likely that there has been a habituation phenomenon during the regeneration and development of the microplants. This includes promoting the tillering of primary or secondary buds due to culturing in the absence of NAA/BAP or NAA/TDZ after a period in the presence of these growth regulators. Histological analyses determined that the adventitious roots were derived from the dedifferentiation of the parenchymal cells located in the basal region of the adventitious buds, with the establishment of rooting pole, due to an auxin gradient. Furthermore, histological and histochemical analyses allowed us to characterize how the PPCs provide niches for multipotent, pluripotent and totipotent stem-like cells for vascular differentiation, organogenesis and somatic embryogenesis in the peach palm. The histological and histochemical analyses also allowed us to detect the unicellular or multicellular origin of somatic embryogenesis. Therefore, our results indicate that the use of growth regulators in microplants can lead to habituation and to different morphogenic pathways leading to potential niche establishment, depending on the positioning of the competent cells and their interaction with neighboring cells. KEY MESSAGE Our results indicate that the use of growth regulators in microplants can lead to habituation and to different morphogenic pathways leading to potential niche establishment, depending on the positioning of the competent cells and their interaction with neighboring cells.
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Affiliation(s)
- Marcilio de Almeida
- Departamento de Ciências Biológicas PPG em Fisiologia e Bioquímica de Plantas e PPG em Recursos Florestais, Escola Superior de Agricultura "Luiz de Queiroz", Universidade de São Paulo, Piracicaba, São Paulo 13.418-900, Brazil.
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11
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Cifuentes-Rojas C, Shippen DE. Telomerase regulation. Mutat Res 2012; 730:20-7. [PMID: 22032831 PMCID: PMC3256259 DOI: 10.1016/j.mrfmmm.2011.10.003] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2011] [Revised: 09/15/2011] [Accepted: 10/12/2011] [Indexed: 02/05/2023]
Abstract
The intimate connection between telomerase regulation and human disease is now well established. The molecular basis for telomerase regulation is highly complex and entails multiple layers of control. While the major target of enzyme regulation is the catalytic subunit TERT, the RNA subunit of telomerase is also implicated in telomerase control. In addition, alterations in gene dosage and alternative isoforms of core telomerase components have been described. Finally, telomerase localization, recruitment to the telomere and enzymology at the chromosome terminus are all subject to modulation. In this review we summarize recent advances in understanding fundamental mechanisms of telomerase regulation.
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Affiliation(s)
| | - Dorothy E. Shippen
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843-2128
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12
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Zhang H, Han W, De Smet I, Talboys P, Loya R, Hassan A, Rong H, Jürgens G, Paul Knox J, Wang MH. ABA promotes quiescence of the quiescent centre and suppresses stem cell differentiation in the Arabidopsis primary root meristem. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2010; 64:764-74. [PMID: 21105924 DOI: 10.1111/j.1365-313x.2010.04367.x] [Citation(s) in RCA: 139] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
It is well known that abscisic acid (ABA) can halt meristems for long periods without loss of meristem function, and can also promote root growth at low concentrations, but the mechanisms underlying such regulation are largely unknown. Here we show that ABA promotes stem cell maintenance in Arabidopsis root meristems by both promoting the quiescence of the quiescent centre (QC) and suppressing the differentiation of stem cells and their daughters. We demonstrate that these two mechanisms of regulation by ABA involve distinct pathways, and identify components in each pathway. Our findings demonstrate a cellular mechanism for a positive role for ABA in promoting root meristem maintenance and root growth in Arabidopsis.
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Affiliation(s)
- Hanma Zhang
- Centre for Plant Sciences, Institute of Integrative and Comparative Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK.
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13
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Lee YW, Kim WT. Tobacco GTBP1, a homolog of human heterogeneous nuclear ribonucleoprotein, protects telomeres from aberrant homologous recombination. THE PLANT CELL 2010; 22:2781-95. [PMID: 20798328 PMCID: PMC2947183 DOI: 10.1105/tpc.110.076778] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2010] [Revised: 07/14/2010] [Accepted: 08/13/2010] [Indexed: 05/07/2023]
Abstract
Telomeres are nucleoprotein complexes essential for the integrity of eukaryotic chromosomes. Cellular roles of single-stranded telomeric DNA binding proteins have been extensively described in yeast and animals, but our knowledge about plant single-strand telomeric factors is rudimentary. Here, we investigated Nicotiana tabacum G-strand-specific single-stranded telomere binding proteins (GTBPs), homologs of a human heterogeneous nuclear ribonucleoprotein. GTBPs bound specifically to the plant single-stranded (TTTAGGG)(4) telomeric repeat element in vitro and were associated with telomeric sequences in tobacco BY-2 suspension cells. Transgenic plants (35S:RNAi-GTBP1), in which GTBP1 was suppressed, exhibited severe developmental anomalies. In addition, the chromosomes of 35S:RNAi-GTBP1 cells displayed elongated telomeres, frequent formation of extrachromosomal telomeric circles, and numerous abnormal anaphase bridges, indicating that GTBP1 knockdown tobacco plants experienced genome instability. GTBP1 inhibited strand invasion, an initial step in interchromosomal homologous recombination. We propose that GTBP1 plays a critical role in telomere structure and function by preventing aberrant interchromosomal telomeric homologous recombination in tobacco.
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Affiliation(s)
| | - Woo Taek Kim
- Department of Biology, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, Korea
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14
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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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15
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Abstract
Plant cells have evolved a complex circuitry to regulate cell division. In many aspects, the plant cell cycle follows a basic strategy similar to other eukaryotes. However, several key issues are unique to plant cells. In this chapter, both the conserved and unique cellular and molecular properties of the plant cell cycle are reviewed. In addition to division of individual cells, the specific characteristic of plant organogenesis and development make that cell proliferation control is of primary importance during development. Therefore, special attention should be given to consider plant cell division control in a developmental context. Proper organogenesis depends on the formation of different cell types. In plants, many of the processes leading to cell differentiation rely on the occurrence of a different cycle, termed the endoreplication cycle, whereby cells undergo repeated full genome duplication events in the absence of mitosis and increase their ploidy. Recent findings are focusing on the relevance of changes in chromatin organization for a correct cell cycle progression and, conversely, in the relevance of a correct functioning of chromatin remodelling complexes to prevent alterations in both the cell cycle and the endocycle.
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Affiliation(s)
- Crisanto Gutierrez
- Centro de Biologia Molecular “Severo Ochoa”, Consejo Superior de Investigaciones Cientificas, Universidad Autonoma de Madrid, Nicolas Cabrera 1, Cantoblanco, 28049 Madrid, Spain
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16
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Identification and characterization of three telomere repeat-binding factors in rice. Biochem Biophys Res Commun 2008; 372:85-90. [PMID: 18477473 DOI: 10.1016/j.bbrc.2008.04.181] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2008] [Accepted: 04/29/2008] [Indexed: 12/16/2022]
Abstract
Telomeres consist of nucleoprotein complexes that protect chromosome end structures. Here, we describe three OsTRBF genes, encoding telomere repeat-binding factors of the single Myb histone family in rice. The predicted proteins contain a Myb DNA-binding motif and a linker histone H1/H5 domain in the N-terminal and central regions, respectively. The OsTRBF transcripts were constitutively detected in rice plants grown under greenhouse conditions. Gel retardation assays showed that these OsTRBF proteins bind specifically to the plant double-stranded telomeric sequence, TTTAGGG, with markedly different binding affinities as judged by their respective dissociation constants. Yeast two-hybrid and in vitro pull-down assays indicated that both OsTRBF1 and OsTRBF2 interact with one another to form homo- and hetero-complexes, while OsTRBF3 appeared to act as a monomer. Our results suggest that OsTRBFs play combinatory roles in the function and structure of telomeres in rice.
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17
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Liu PF, Chang WC, Wang YK, Chang HY, Pan RL. Signaling pathways mediating the suppression of Arabidopsis thaliana Ku gene expression by abscisic acid. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2008; 1779:164-74. [DOI: 10.1016/j.bbagrm.2007.12.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2007] [Revised: 12/10/2007] [Accepted: 12/10/2007] [Indexed: 11/28/2022]
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18
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Liu PF, Chang WC, Wang YK, Munisamy SB, Hsu SH, Chang HY, Wu SH, Pan RL. Differential regulation of Ku gene expression in etiolated mung bean hypocotyls by auxins. ACTA ACUST UNITED AC 2007; 1769:443-54. [PMID: 17507104 DOI: 10.1016/j.bbaexp.2007.04.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2006] [Revised: 03/15/2007] [Accepted: 04/03/2007] [Indexed: 10/23/2022]
Abstract
Plant Ku genes were identified very recently in Arabidopsis thaliana, and their roles in repair of double-stranded break DNA and maintenance of telomere integrity were scrutinized. In this study, the cDNAs encoding Ku70 (VrKu70) and Ku80 (VrKu80) were isolated from mung bean (Vigna radiata L.) hypocotyls. Both genes were expressed widely among different tissues of mung bean with the highest levels in hypocotyls and leaves. The VrKu gene expression was stimulated by exogenous auxins in a concentration- and time-dependent manner. The stimulation could be abolished by auxin transport inhibitors, N-(1-naphthyl) phthalamic acid and 2,3,5-triiodobenzoic acid implicating that exogenous auxins triggered the effects following their uptake by the cells. Further analysis using specific inhibitors of auxin signaling showed that the stimulation of VrKu expression by 2,4-dichlorophenoxyacetic acid (2,4-D) was suppressed by intracellular Ca(2+) chelators, calmodulin antagonists, and calcium/calmodulin dependent protein kinase inhibitors, suggesting the involvement of calmodulin in the signaling pathway. On the other hand, exogenous indole-3-acetic acid (IAA) and alpha-naphthalene acetic acid (NAA) stimulated VrKu expression through the mitogen-activated protein kinase/extracellular signal-regulated kinase pathway. Altogether, it is thus proposed that 2,4-D and IAA (or NAA) regulate the expression of VrKu through two distinct pathways.
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Affiliation(s)
- Pei-Feng Liu
- Department of Life Sciences and Institute of Bioinformatics and Structural Biology, National Tsing Hua University, Hsin Chu, Taiwan 30043, Republic of China
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19
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Tomlinson RL, Ziegler TD, Supakorndej T, Terns RM, Terns MP. Cell cycle-regulated trafficking of human telomerase to telomeres. Mol Biol Cell 2005; 17:955-65. [PMID: 16339074 PMCID: PMC1356603 DOI: 10.1091/mbc.e05-09-0903] [Citation(s) in RCA: 209] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Telomerase synthesizes telomeres at the ends of human chromosomes during S phase. The results presented here suggest that telomerase activity may be regulated by intranuclear trafficking of the key components of the enzyme in human cells. We examined the subcellular localization of endogenous human telomerase RNA (hTR) and telomerase reverse transcriptase (hTERT) in HeLa cervical carcinoma cells. Throughout most of the cell cycle, we found that the two essential components of telomerase accumulate at intranuclear sites separate from telomeres. However, during S phase, both hTR and hTERT are specifically recruited to subsets of telomeres. The localization of telomerase to telomeres is dynamic, peaking at mid-S phase. We also found complex associations of both hTR and hTERT with nucleoli and Cajal bodies during S phase, implicating both structures in the biogenesis and trafficking of telomerase. Our results mark the first observation of human telomerase at telomeres and provide a mechanism for the cell cycle-dependent regulation of telomere synthesis in human cells.
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Affiliation(s)
- Rebecca L Tomlinson
- Departments of Biochemistry and Molecular Biology and Genetics, University of Georgia, Athens, GA 30602, USA
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20
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Abstract
The role model systems have played in understanding telomere biology has been enormous, and understanding has rapidly transferred to human telomere research. Most work using model organisms to study telomerase and nontelomerase-based telomere-maintenance systems has centered on yeasts, ciliates, and insects. But it is now timely to put considerably more effort into plant models for a number of reasons: (i) the rice and Arabidopsis genome sequencing projects make data mining possible; (ii) extensive collections of insertion mutants of Arabidopsis thaliana enable phenotypic effects of protein gene knockouts to be analyzed, including for those genes involved in telomere structure, function (including, for example, in meiosis), and maintenance; and (iii) the variability of plant telomeres is considerable and ranges from the telomerase-mediated synthesis of the Arabidopsis-type (TTTAGGG) and vertebrate-type (TTAGGG) repeats to sequences synthesized by telomerase-independent mechanism(s) that are still to be discovered. Here we describe how the understanding of telomere biology has been advanced by methods used to isolate telomeric sequences and prove that the putative sequences isolated are indeed telomeric. We show how assays designed to prove the activity of telomerase [e.g., telomeric repeat amplification protocol (TRAP)] lead not only to an understanding of telomere structure and function, but also to the understanding of cell activity in development and in the cell cycle. We review how assays designed to reveal protein/protein and protein/nucleic acid interactions promote understanding of the structure and activities of plant telomeres. Together, the data are making significant contributions to telomere biology in general and could have medical implications.
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Affiliation(s)
- Jirí Fajkus
- Academy of Sciences of the Czech Republic, Brno, Czech Republic.
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21
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Oguchi K, Tamura K, Takahashi H. Characterization of Oryza sativa telomerase reverse transcriptase and possible role of its phosphorylation in the control of telomerase activity. Gene 2005; 342:57-66. [PMID: 15527966 DOI: 10.1016/j.gene.2004.07.011] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2004] [Revised: 07/05/2004] [Accepted: 07/19/2004] [Indexed: 01/01/2023]
Abstract
Telomerase reverse transcriptase (TERT) has been characterized in the dicotyledon Arabidopsis thaliana. A TERT homolog has now been identified in the monocotyledon rice (Oryza sativa L.) on the basis of its predicted homology to the A. thaliana enzyme (AtTERT). At least five alternatively spliced transcripts of the rice TERT (OsTERT) gene were detected. The full-length OsTERT protein shares structural features with TERTs of other species, including a calculated molecular size of 144 kDa, an isoelectric point of 9.6, and conserved sequence motifs. Phylogenetic analysis showed that OsTERT clusters with AtTERT and is more related to the human and mouse enzymes than to those of yeast and ciliated protozoa, consistent with the evolutionary relations among these eukaryotes. Telomerase activity was abundant in shoot apices and cultured cells but was low or absent in leaves or roots of rice plants, whereas similarly spliced OsTERT transcripts were detected in all tissues examined and cultured cells. Similar to mouse and human TERT proteins, OsTERT contains two putative phosphorylation sites for Akt kinase. Incubation of a rice cell extract with Akt or with protein phosphatase 2A potentiated or inhibited telomerase activity, respectively, whereas Akt did not affect the activity in Arabidopsis cell extract. In addition, the kinase activated the telomerase in a leaf extract. The mechanism of telomerase regulation in rice thus appears to differ from that in Arabidopsis (which is mediated predominantly at the level of AtTERT transcription), possibly reflecting the taxonomic distance between monocotyledons and dicotyledons.
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Affiliation(s)
- Keiko Oguchi
- Institute of Molecular and Cellular Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan
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22
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Abstract
The stability of eukaryotic genomes is provided in part by the integrity of telomeres, the nucleoprotein caps on the ends of chromosome. Recent studies reveal that proper telomere architecture is required for long-term proliferation capacity. Here we describe molecular mechanisms that protect and maintain chromosome ends and discuss why Arabidopsis is emerging as a powerful new model for elucidating fundamental aspects of telomere biology.
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Affiliation(s)
- Karel Riha
- Department of Biochemistry and Biophysics, Texas A&M University, 2128 TAMU, College Station, Texas 77843-2128, USA
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23
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Sánchez JP, Duque P, Chua NH. ABA activates ADPR cyclase and cADPR induces a subset of ABA-responsive genes in Arabidopsis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2004; 38:381-95. [PMID: 15086800 DOI: 10.1111/j.1365-313x.2004.02055.x] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Cyclic ADP-ribose (cADPR) was previously shown to activate transient expression of two abscisic acid (ABA)-responsive genes in tomato cells. Here, we show that the activity of the enzyme responsible for cADPR synthesis, ADP-ribosyl (ADPR) cyclase, is rapidly induced by ABA in both wild-type (WT) and abi1-1 mutant Arabidopsis plants in the absence of protein synthesis. Furthermore, in transgenic Arabidopsis plants, induced expression of the Aplysia ADPR cyclase gene resulted in an increase in ADPR cyclase activity and cADPR levels, as well as elevated expression of ABA-responsive genes KIN2, RD22, RD29a, and COR47 (although to a lesser extent than after ABA induction). Genome-wide profiling indicated that about 28% of all ABA-responsive genes in Arabidopsis are similarly up- and downregulated by cADPR and contributed to the identification of new ABA-responsive genes. Our results suggest that activation of ADPR cyclase is an early ABA-signaling event partially insensitive to the abi1-1 mutation and that an increase in cADPR plays an important role in downstream molecular and physiological ABA responses.
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Affiliation(s)
- Juan-Pablo Sánchez
- Laboratory of Plant Molecular Biology, The Rockefeller University, 1230 York Avenue, New York, NY 10021, USA
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25
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Yang SW, Kim DH, Lee JJ, Chun YJ, Lee JH, Kim YJ, Chung IK, Kim WT. Expression of the telomeric repeat binding factor gene NgTRF1 is closely coordinated with the cell division program in tobacco BY-2 suspension culture cells. J Biol Chem 2003; 278:21395-407. [PMID: 12646586 DOI: 10.1074/jbc.m209973200] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Telomeres are vital for preserving chromosome integrity during cell division. Several genes encoding potential telomere-binding proteins have recently been identified in higher plants, but nothing is known about their function or regulation during cell division. In this study, we have isolated and characterized a cDNA clone, pNgTRF1, encoding a putative double-stranded telomeric repeat binding factor of Nicotiana glutinosa, a diploid tobacco plant. The predicted protein sequence of NgTRF1 (Mr = 75,000) contains a single Myb-like domain with significant homology to a corresponding motif in human TRF1/Pin2 and TRF2. Gel retardation assays revealed that bacterially expressed full-length NgTRF1 was able to form a specific complex only with probes containing three or more contiguous telomeric TTTAGGG repeats. The Myb-like domain of NgTRF1 is essential, but not sufficient, to bind the telomeric repeat sequence. The glutamine-rich extreme C-terminal region, which does not exist in animal proteins, was additionally required to form a specific telomere-protein complex. The dissociation constant (Kd) of the Myb motif plus the glutamine-rich domain of NgTRF1 to the two-telomeric repeat sequence was evaluated to be 4.5 +/- 0.2 x 10-9 m, which is comparable to that of the Myb domain of human TRF1. Expression analysis showed that NgTRF1 gene activity was inversely correlated with the cell division capacity of tobacco root cells and during the 9-day culture period of BY-2 suspension cells, while telomerase activity was positively correlated with cell division. In synchronized BY-2 cells, NgTRF1 was selectively expressed in G1 phase, whereas telomerase activity peaked in S phase. These findings suggest that telomerase activity and NgTRF1 expression are differentially regulated in an opposing fashion during growth and cell division in tobacco plants. The possible physiological functions of NgTRF1 in tobacco cells are also discussed.
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MESH Headings
- Amino Acid Motifs
- Amino Acid Sequence
- Arabidopsis/genetics
- Base Sequence
- Binding, Competitive
- Blotting, Northern
- Blotting, Southern
- Cell Division
- Cell Nucleus/metabolism
- Cloning, Molecular
- DNA/metabolism
- DNA, Complementary/metabolism
- Dose-Response Relationship, Drug
- G1 Phase
- Gene Deletion
- Gene Expression Regulation
- Gene Library
- Green Fluorescent Proteins
- Humans
- Indomethacin/pharmacology
- Kinetics
- Luminescent Proteins/metabolism
- Models, Genetic
- Molecular Sequence Data
- Mutation
- Nucleic Acid Hybridization
- Polymerase Chain Reaction
- Protein Binding
- Protein Structure, Tertiary
- RNA, Messenger/metabolism
- S Phase
- Sequence Homology, Amino Acid
- Species Specificity
- Subcellular Fractions
- Telomerase/metabolism
- Telomere/genetics
- Telomere/metabolism
- Telomeric Repeat Binding Protein 1/biosynthesis
- Telomeric Repeat Binding Protein 1/genetics
- Time Factors
- Nicotiana/genetics
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Affiliation(s)
- Seong Wook Yang
- Department of Biology, College of Science, Yonsei University, Seoul 120-749, Korea
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26
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Gutierrez C, Ramirez-Parra E, Castellano MM, del Pozo JC. G(1) to S transition: more than a cell cycle engine switch. CURRENT OPINION IN PLANT BIOLOGY 2002; 5:480-6. [PMID: 12393009 DOI: 10.1016/s1369-5266(02)00301-1] [Citation(s) in RCA: 96] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
CDK-cyclin complexes are the universal drivers of cell cycle transitions. Progression through G(1) and transition to S-phase, thereby initiating genome duplication, requires the concerted action of cyclin-dependent kinase (CDK)-cyclin complexes on specific targets. These targets belong to at least two major regulatory networks: the retinoblastoma-related (RBR)/E2F pathway and complexes that are responsible for the initiation of DNA replication. The G(1) phase is central to the integration of signals that regulate both the exit from the cell division cycle to differentiation and the reactivation of cell proliferation. Cellular factors that are involved in these pathways play a role in regulating cell size and number, and organogenesis. As a consequence, they are also involved in determining plant architecture.
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Affiliation(s)
- Crisanto Gutierrez
- Centro de Biologia Molecular 'Severo Ochoa', Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, Cantoblanco, 28049, Madrid, Spain.
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