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Lin XJ, Wang ML, Kong WW, Mo BX. Molecular Studies on Plant Telomeres: Expanding Horizons in Plant Biology. ACS Synth Biol 2025. [PMID: 40340407 DOI: 10.1021/acssynbio.4c00846] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/10/2025]
Abstract
The integrity of plant genomes is intricately safeguarded by telomeres, the protective caps located at the ends of the chromosome. This review provides a comprehensive analysis of the molecular mechanisms governing the structure, maintenance, and dynamics of plant telomeres, highlighting their genetic and epigenetic regulation and their pivotal roles in plant development, longevity, stress adaptation, and disease resistance. Recent advancements, such as next-generation sequencing and single-molecule imaging, have revolutionized our understanding of telomere biology, unveiling new insights into telomerase activity and telomere-associated genetic variants. Additionally, the review also discusses the challenges and future directions of telomere research, including the potential applications of telomere biology in plant breeding and genetic engineering.
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Affiliation(s)
- Xiao J Lin
- Guangdong Provincial Key Laboratory for Plant Epigenetics, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen 518060, China
| | - Ming L Wang
- Guangdong Provincial Key Laboratory for Plant Epigenetics, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen 518060, China
| | - Wen W Kong
- Guangdong Provincial Key Laboratory for Plant Epigenetics, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen 518060, China
| | - Bei X Mo
- Guangdong Provincial Key Laboratory for Plant Epigenetics, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen 518060, China
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Chen YJ, Campbell HG, Wiles AK, Eccles MR, Reddel RR, Braithwaite AW, Royds JA. PAX8 Regulates Telomerase Reverse Transcriptase and Telomerase RNA Component in Glioma. Cancer Res 2008; 68:5724-32. [DOI: 10.1158/0008-5472.can-08-0058] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Zhang P, Xu Q, Chen WT, Duan LQ, Zhang ZY, Zhou XJ. Synergistic down-regulation of telomerase by all-trans retinoic acid and antisense oligonucleotide in oral squamous cell carcinoma cell line (Tca8113). Oral Oncol 2006; 41:909-15. [PMID: 16051514 DOI: 10.1016/j.oraloncology.2005.05.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2005] [Accepted: 05/06/2005] [Indexed: 11/21/2022]
Abstract
Human telomerase, activated in about 90% of cancers, is mainly composed of hTR, hTERT and TP1. The exposed RNA template of hTR is an ideal target for antisense oligonucleotides (As-ODN); while recent findings indicate all-trans retinoid acid (ATRA) could effectively inhibit the expression of catalytic subunit-hTERT. The aim of this study was to investigate the effect of ATRA and As-ODN in oral squamous cell carcinoma and whether telomerase activity could be synergistically inhibited by them and thus therapeutically exploited in the future. As-ODN-hTR was transfected into human tongue squamous cell carcinoma cell line (Tca8113) with or without ATRA. Telomerase activity was examined by PCR-Elisa; viability was compared with growth curve; apoptotic rate was analyzed by Annexin V/PI double staining and hTERT expression was tested with western blot. Tca8113 cells displayed significant growth inhibition during the 9-day exposure to ATRA/As-ODN, especially to a combination of As-ODN-hTR and 5muM ATRA, correlating with the inhibition of telomerase expression. The relative telomerase activity was inhibited during treated with As-ODN-hTR alone, ATRA alone, or a combination of them. While without ATRA, the effect of As-ODN would disappear at 96h after transfection. As-ODN-hTR alone or combined with ATRA also significantly increase the apoptotic rate. Our findings provided direct evidence, in oral squamous cell carcinoma, As-ODN-hTR and ATRA could synergistically inhibit telomerase activity and telomerase protein in human tongue squamous cell carcinoma cells, which correlated with the induction of growth arrest.
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Affiliation(s)
- Ping Zhang
- Department of Oral and Maxillofacial Surgery, The Ninth People's Hospital, Shanghai Second Medical University, 639 Zhizaoju Road, Shanghai 200011, China
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Lin CY, Chang HH, Wu KJ, Tseng SF, Lin CC, Lin CP, Teng SC. Extrachromosomal telomeric circles contribute to Rad52-, Rad50-, and polymerase delta-mediated telomere-telomere recombination in Saccharomyces cerevisiae. EUKARYOTIC CELL 2005; 4:327-36. [PMID: 15701795 PMCID: PMC549320 DOI: 10.1128/ec.4.2.327-336.2005] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Telomere maintenance is required for chromosome stability, and telomeres are typically replicated by the telomerase reverse transcriptase. In both tumor and yeast cells that lack telomerase, telomeres are maintained by an alternative recombination mechanism. By using an in vivo inducible Cre-loxP system to generate and trace the fate of marked telomeric DNA-containing rings, the efficiency of telomere-telomere recombination can be determined quantitatively. We show that the telomeric loci are the primary sites at which a marked telomeric ring-containing DNA is observed among wild-type and surviving cells lacking telomerase. Marked telomeric DNAs can be transferred to telomeres and form tandem arrays through Rad52-, Rad50-, and polymerase delta-mediated recombination. Moreover, increases of extrachromosomal telomeric and Y' rings were observed in telomerase-deficient cells. These results imply that telomeres can use looped-out telomeric rings to promote telomere-telomere recombination in telomerase-deficient Saccharomyces cerevisiae.
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Affiliation(s)
- Chi-Ying Lin
- Department of Microbiology, National Taiwan University College of Medicine,Taipei 10018, Taiwan
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Jiang YA, Luo HS, Fan LF, Jiang CQ, Chen WJ. Effect of antisense oligodeoxynucleotide of telomerase RNA on telomerase activity and cell apoptosis in human colon cancer. World J Gastroenterol 2004; 10:443-5. [PMID: 14760776 PMCID: PMC4724912 DOI: 10.3748/wjg.v10.i3.443] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
AIM: To explore the effect of antisense oligodeoxynucleotide (As-ODN) of telomerase RNA on telomerase activity and cell apoptosis in human colon cancer.
METHODS: As-ODN was transfected into SW480 cells by liposomal transfection reagent. Telomerase activity of SW480 cells was examined by telomeric repeat amplification protocol (TRAP) and enzyme-linked immunosorbent assay (ELISA). Apoptosis was analyzed by morphology and flow cytometry.
RESULTS: The telomerase activity in SW480 cells transfected with 1.0 μmol/L of As-ODN for 2-5 days, was significantly decreased in a time-dependent manner, and the cells underwent apoptosis. The missense ODN (Ms-ODN) and the control group transfected with SW480 cells did not show these changes.
CONCLUSION: As-ODN can specifically inhibit the telomerase activity of SW480 cells and induce apoptosis.
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Affiliation(s)
- Ying-An Jiang
- Department of Gastroenterology, Renming Hospital of Wuhan University, Hubei Province, China
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Abstract
Telomerase is a ribonucleoprotein reverse transcriptase with two subunits critical for catalytic activity, the protein telomerase reverse transcriptase (TERT) and telomerase RNA. In this study, we establish additional roles of the telomerase RNA subunit by demonstrating that RNA motifs stimulate the processivity of nucleotide and repeat addition. These functions are both functionally and physically separable from the roles of other RNA motifs in establishing a properly defined template. Binding of Tetrahymena telomerase RNA stem IV to TERT enhances nucleotide addition processivity, while a cooperation of the RNA pseudoknot and stem IV promotes repeat addition processivity. The low processivity of DNA synthesis by telomerase ribonucleoproteins lacking the pseudoknot and/or stem IV can be rescued by addition of the deleted region in trans. These findings demonstrate RNA elements with roles in telomerase elongation processivity that are distinct from RNA elements that specify the internal template.
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Tsai YL, Tseng SF, Chang SH, Lin CC, Teng SC. Involvement of replicative polymerases, Tel1p, Mec1p, Cdc13p, and the Ku complex in telomere-telomere recombination. Mol Cell Biol 2002; 22:5679-87. [PMID: 12138180 PMCID: PMC133992 DOI: 10.1128/mcb.22.16.5679-5687.2002] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Telomere maintenance is required for chromosome stability, and telomeres are typically replicated by the action of the reverse transcriptase telomerase. In both tumor and yeast cells that lack telomerase, telomeres are maintained by an alternative recombination mechanism. Genetic studies have led to the identification of DNA polymerases, cell cycle checkpoint proteins, and telomere binding proteins involved in the telomerase pathway. However, how these proteins affect telomere-telomere recombination has not been identified to date. Using an assay to trace the in vivo recombinational products throughout the course of survivor development, we show here that three major replicative polymerases, alpha, delta, and epsilon, play roles in telomere-telomere recombination and that each causes different effects and phenotypes when they as well as the telomerase are defective. Polymerase delta appears to be the main activity for telomere extension, since neither type I nor type II survivors arising via telomere-telomere recombination were seen in its absence. The frequency of type I versus type II is altered in the polymerase alpha and epsilon mutants relative to the wild type. Each prefers to develop a particular type of survivor. Moreover, type II recombination is mediated by the cell cycle checkpoint proteins Tel1 and Mec1, and telomere-telomere recombination is regulated by telomere binding protein Cdc13 and the Ku complex. Together, our results suggest that coordination between DNA replication machinery, DNA damage signaling, DNA recombination machinery, and the telomere protein-DNA complex allows telomere recombination to repair telomeric ends in the absence of telomerase.
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Affiliation(s)
- Yun-Luen Tsai
- Department of Microbiology, National Taiwan University College of Medicine, Taipei, Taiwan, Republic of China
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Feng RH, Zhu ZG, Li JF, Liu BY, Yan M, Yin HR, Lin YZ. Inhibition of human telomerase in MKN-45 cell line by antisense hTR expression vector induces cell apoptosis and growth arrest. World J Gastroenterol 2002; 8:436-40. [PMID: 12046065 PMCID: PMC4656416 DOI: 10.3748/wjg.v8.i3.436] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIM: To investigate the effects of antisense human telomerase RNA (hTR) on the biologic behavior of human gastric cancer cell line: MKN-45 by gene transfection and its potential role in the gene therapy of gastric cancer.
METHODS: The hTR cDNA fragment was cloned from MKN-45 through RT-PCR and subcloned into eukaryotic expression vector (pEF6/V5-His-TOPO) in cis-direction or trans-direction by DNA recombinant methods. The constructed sense, antisense and empty vectors were transfected into MKN-45 cell lines separately by lipofectin-mediated DNA transfection technology. After drug selection, the expression of antisense hTR gene in stable transfectants and normal MKN-45 cells was detected by RT-PCR, the telomerase activity by TRAP, the apoptotic features by PI and Hoechst 33258 staining, the cell cycle distribution by flow cytometry and the population doubling time by cell counting. Comparison among the stable transfectants and normal MKN-45 cells was made.
RESULTS: The sense, antisense hTR eukaryotic expression vectors and empty vector were successfully constructed and proved to be the same as original design by restriction endonuclease analysis and sequencing. Then, they were successfully transfected into MKN-45 cell lines separately with lipofectin. The expression of antisense hTR gene was only detected in MKN-45 cells stably transfected with antisense hTR vector (named as MKN-45-ahTR) but not in the control cells. In MKN-45-ahTR, the telomerase activity was inhibited by 75%, the apoptotic rate was increased to 25.3%, the percentage of cells in the G0/G1 phase was increased to 65%, the proliferation index was decreased to 35% and the population doubling time was prolonged to 35.3 h. However, the telomerase activity, the apoptotic rate, the distribution of cell cycle, the proliferation index and the population doubling time were not different among the control cells.
CONCLUSION: Antisense hTR can significantly inhibit telomerase activity and proliferation of MKN-45 cells and induce cell apoptosis. Antisense gene therapy based on telomerase inhibition can be a potential therapeutic approach to the treatment of gastric cancer.
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Affiliation(s)
- Run-Hua Feng
- Shanghai Institute of Digestive Surgery, Ruijin Hospital, Shanghai Second Medical University, Shanghai 200025, China
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Eversole A, Maizels N. In vitro properties of the conserved mammalian protein hnRNP D suggest a role in telomere maintenance. Mol Cell Biol 2000; 20:5425-32. [PMID: 10891483 PMCID: PMC85994 DOI: 10.1128/mcb.20.15.5425-5432.2000] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Mammalian chromosomes terminate with a 3' tail which consists of reiterations of the G-rich repeat, d(TTAGGG). The telomeric tail is the primer for replication by telomerase, and it may also invade telomeric duplex DNA to form terminal lariat structures, or T loops. Here we show that the ubiquitous and highly conserved mammalian protein hnRNP D interacts specifically with the G-rich strand of the telomeric repeat. A single gene encodes multiple isoforms of hnRNP D. All isoforms bind comparably to the G-rich strand, and certain isoforms can also bind tightly and specifically to the C-rich telomeric strand. G-rich telomeric sequences readily form structures stabilized by G-G pairing, which can interfere with telomere replication by telomerase. We show that hnRNP D binding to the G-rich strand destabilizes intrastrand G-G pairing and that hnRNP D interacts specifically with telomerase in human cell extracts. This biochemical analysis suggest that hnRNP D could function in vivo to destabilize structures formed by telomeric G-rich tails and facilitate their extension by telomerase.
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Affiliation(s)
- A Eversole
- Departments of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, Connecticut 06520-8024, USA
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Abstract
The telomerase ribonucleoprotein has a phylogenetically divergent RNA subunit, which contains a short template for telomeric DNA synthesis. To understand how telomerase RNA participates in mechanistic aspects of telomere synthesis, we studied a conserved secondary structure adjacent to the template. Disruption of this structure caused DNA synthesis to proceed beyond the normal template boundary, resulting in altered telomere sequences, telomere shortening, and cellular growth defects. Compensatory mutations restored normal telomerase function. Thus, the RNA structure, rather than its sequence, specifies the template boundary. This study reveals a specific function for an RNA structure in the enzymatic action of telomerase.
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Affiliation(s)
- Y Tzfati
- Department of Microbiology and Immunology, University of California, San Francisco, San Francisco, CA 94143-0414, USA
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