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Watson JM, Trieb J, Troestl M, Renfrew K, Mandakova T, Fulnecek J, Shippen DE, Riha K. A hypomorphic allele of telomerase uncovers the minimal functional length of telomeres in Arabidopsis. Genetics 2021; 219:6339584. [PMID: 34849882 DOI: 10.1093/genetics/iyab126] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2021] [Accepted: 07/23/2021] [Indexed: 12/23/2022] Open
Abstract
Despite the essential requirement of telomeric DNA for genome stability, the length of telomere tracts between species substantially differs, raising the question of the minimal length of telomeric DNA necessary for proper function. Here, we address this question using a hypomorphic allele of the telomerase catalytic subunit, TERT. We show that although this construct partially restored telomerase activity to a tert mutant, telomeres continued to shorten over several generations, ultimately stabilizing at a bimodal size distribution. Telomeres on two chromosome arms were maintained at a length of 1 kb, while the remaining telomeres were maintained at 400 bp. The longest telomeres identified in this background were also significantly longer in wild-type populations, suggesting cis-acting elements on these arms either promote telomerase processivity or recruitment. Genetically disrupting telomerase processivity in this background resulted in immediate lethality. Thus, telomeres of 400 bp are both necessary and sufficient for Arabidopsis viability. As this length is the estimated minimal length for t-loop formation, our data suggest that telomeres long enough to form a t-loop constitute the minimal functional length.
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Affiliation(s)
- J Matthew Watson
- Gregor Mendel Institute of Plant Molecular Biology, Austrian Academy of Sciences, 1030 Vienna, Austria
| | - Johanna Trieb
- Gregor Mendel Institute of Plant Molecular Biology, Austrian Academy of Sciences, 1030 Vienna, Austria
| | - Martina Troestl
- Gregor Mendel Institute of Plant Molecular Biology, Austrian Academy of Sciences, 1030 Vienna, Austria
| | - Kyle Renfrew
- Department of Biochemistry, Texas A&M University, College Station, TX 77840, USA
| | - Terezie Mandakova
- Central European Institute of Technology, Masaryk University, 625 00 Brno, Czech Republic
| | - Jaroslav Fulnecek
- Central European Institute of Technology, Masaryk University, 625 00 Brno, Czech Republic
| | - Dorothy E Shippen
- Department of Biochemistry, Texas A&M University, College Station, TX 77840, USA
| | - Karel Riha
- Central European Institute of Technology, Masaryk University, 625 00 Brno, Czech Republic
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2
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Berei J, Eckburg A, Miliavski E, Anderson AD, Miller RJ, Dein J, Giuffre AM, Tang D, Deb S, Racherla KS, Patel M, Vela MS, Puri N. Potential Telomere-Related Pharmacological Targets. Curr Top Med Chem 2020; 20:458-484. [DOI: 10.2174/1568026620666200109114339] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Revised: 11/21/2019] [Accepted: 11/21/2019] [Indexed: 12/22/2022]
Abstract
Telomeres function as protective caps at the terminal portion of chromosomes, containing
non-coding nucleotide sequence repeats. As part of their protective function, telomeres preserve genomic
integrity and minimize chromosomal exposure, thus limiting DNA damage responses. With
continued mitotic divisions in normal cells, telomeres progressively shorten until they reach a threshold
at a point where they activate senescence or cell death pathways. However, the presence of the enzyme
telomerase can provide functional immortality to the cells that have reached or progressed past
senescence. In senescent cells that amass several oncogenic mutations, cancer formation can occur due
to genomic instability and the induction of telomerase activity. Telomerase has been found to be expressed
in over 85% of human tumors and is labeled as a near-universal marker for cancer. Due to this
feature being present in a majority of tumors but absent in most somatic cells, telomerase and telomeres
have become promising targets for the development of new and effective anticancer therapeutics.
In this review, we evaluate novel anticancer targets in development which aim to alter telomerase
or telomere function. Additionally, we analyze the progress that has been made, including preclinical
studies and clinical trials, with therapeutics directed at telomere-related targets. Furthermore, we review
the potential telomere-related therapeutics that are used in combination therapy with more traditional
cancer treatments. Throughout the review, topics related to medicinal chemistry are discussed,
including drug bioavailability and delivery, chemical structure-activity relationships of select therapies,
and the development of a unique telomere assay to analyze compounds affecting telomere elongation.
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Affiliation(s)
- Joseph Berei
- Department of Biomedical Sciences, University of Illinois College of Medicine at Rockford, Rockford, IL 61107, United States
| | - Adam Eckburg
- Department of Biomedical Sciences, University of Illinois College of Medicine at Rockford, Rockford, IL 61107, United States
| | - Edward Miliavski
- Department of Biomedical Sciences, University of Illinois College of Medicine at Rockford, Rockford, IL 61107, United States
| | - Austin D. Anderson
- Department of Biomedical Sciences, University of Illinois College of Medicine at Rockford, Rockford, IL 61107, United States
| | - Rachel J. Miller
- Department of Biomedical Sciences, University of Illinois College of Medicine at Rockford, Rockford, IL 61107, United States
| | - Joshua Dein
- Department of Biomedical Sciences, University of Illinois College of Medicine at Rockford, Rockford, IL 61107, United States
| | - Allison M. Giuffre
- Department of Biomedical Sciences, University of Illinois College of Medicine at Rockford, Rockford, IL 61107, United States
| | - Diana Tang
- Department of Biomedical Sciences, University of Illinois College of Medicine at Rockford, Rockford, IL 61107, United States
| | - Shreya Deb
- Department of Biomedical Sciences, University of Illinois College of Medicine at Rockford, Rockford, IL 61107, United States
| | - Kavya Sri Racherla
- Department of Biomedical Sciences, University of Illinois College of Medicine at Rockford, Rockford, IL 61107, United States
| | - Meet Patel
- Department of Biomedical Sciences, University of Illinois College of Medicine at Rockford, Rockford, IL 61107, United States
| | - Monica Saravana Vela
- Department of Biomedical Sciences, University of Illinois College of Medicine at Rockford, Rockford, IL 61107, United States
| | - Neelu Puri
- Department of Biomedical Sciences, University of Illinois College of Medicine at Rockford, Rockford, IL 61107, United States
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3
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Should we consider telomere length and telomerase activity in male factor infertility? Curr Opin Obstet Gynecol 2019; 30:197-202. [PMID: 29664790 DOI: 10.1097/gco.0000000000000451] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
PURPOSE OF REVIEW The purpose of this review is to analyze what is known to date about the relation between telomeres and male fertility, and if it is possible for telomeres, or elements related to them, to be used as new prognostic biomarkers in fertility treatment. RECENT FINDINGS Cells in germ series, including spermatozoids, have longer telomeres (10-20 kb), and do not seem to undergo the shortening that takes place in somatic cells with age as they present telomerase activity. Longer telomere length found in the sperm of older fathers, influences their offspring possessing cells with longer telomere length. Infertile patients have spermatozoids with shorter telomere length than fertile people, but telomere length does neither correlate with the sperm concentration, mobility or morphology, nor with the DNA fragmentation indices (DFI) of spermatozoids. Embryo quality rate and transplantable embryo rate are related with the telomere length of spermatozoids (STL), but pregnancy rates are not affected. SUMMARY Telomere length and telomerase levels can be used as biomarkers of male fertility. Higher STL can have beneficial effects on fertility, thus the use of spermatozoids with longer telomere length in an assisted reproduction technique (ART) could be one way of solving some infertility cases.
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4
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Zhang Z, Zhang T, Ge Y, Tang M, Ma W, Zhang Q, Gong S, Wright WE, Shay J, Liu H, Zhao Y. 2D gel electrophoresis reveals dynamics of t-loop formation during the cell cycle and t-loop in maintenance regulated by heterochromatin state. J Biol Chem 2019; 294:6645-6656. [PMID: 30819801 DOI: 10.1074/jbc.ra119.007677] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Revised: 02/20/2019] [Indexed: 12/15/2022] Open
Abstract
Linear chromosome ends are capped by telomeres that have been previously reported to adopt a t-loop structure. The lack of simple methods for detecting t-loops has hindered progress in understanding the dynamics of t-loop formation and its function in protecting chromosome ends. Here, we employed a classical two-dimensional agarose gel method (2D gel method) to innovatively apply to t-loop detection. Briefly, restriction fragments of genomic DNA were separated in a 2D gel, and the telomere sequence was detected by in-gel hybridization with telomeric probe. Using this method, we found that t-loops are present throughout the cell cycle, and t-loop formation tightly couples to telomere replication. We also observed that t-loop abundance positively correlates with chromatin condensation, i.e. cells with less compact telomeric chromatin (ALT cells and trichostatin A (TSA)-treated HeLa cells) exhibited fewer t-loops. Moreover, we observed that telomere dysfunction-induced foci, ALT-associated promyelocytic leukemia bodies, and telomere sister chromatid exchanges are activated upon TSA-induced loss of t-loops. These findings confirm the importance of the t-loop in protecting linear chromosomes from damage or illegitimate recombination.
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Affiliation(s)
- Zepeng Zhang
- From the MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Tianpeng Zhang
- From the MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Yuanlong Ge
- From the MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Mengfan Tang
- From the MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Wenbin Ma
- From the MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Qinfen Zhang
- From the MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Shengzhao Gong
- Department of Chemical Engineering, Guangdong Industry Technical College, Guangzhou 510006, China
| | - Woodring E Wright
- the Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390, and
| | - Jerry Shay
- the Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390, and
| | - Haiying Liu
- From the MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China,
| | - Yong Zhao
- From the MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China,
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5
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Aksenova AY, Mirkin SM. At the Beginning of the End and in the Middle of the Beginning: Structure and Maintenance of Telomeric DNA Repeats and Interstitial Telomeric Sequences. Genes (Basel) 2019; 10:genes10020118. [PMID: 30764567 PMCID: PMC6410037 DOI: 10.3390/genes10020118] [Citation(s) in RCA: 58] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2019] [Revised: 01/30/2019] [Accepted: 01/30/2019] [Indexed: 02/07/2023] Open
Abstract
Tandem DNA repeats derived from the ancestral (TTAGGG)n run were first detected at chromosome ends of the majority of living organisms, hence the name telomeric DNA repeats. Subsequently, it has become clear that telomeric motifs are also present within chromosomes, and they were suitably called interstitial telomeric sequences (ITSs). It is well known that telomeric DNA repeats play a key role in chromosome stability, preventing end-to-end fusions and precluding the recurrent DNA loss during replication. Recent data suggest that ITSs are also important genomic elements as they confer its karyotype plasticity. In fact, ITSs appeared to be among the most unstable microsatellite sequences as they are highly length polymorphic and can trigger chromosomal fragility and gross chromosomal rearrangements. Importantly, mechanisms responsible for their instability appear to be similar to the mechanisms that maintain the length of genuine telomeres. This review compares the mechanisms of maintenance and dynamic properties of telomeric repeats and ITSs and discusses the implications of these dynamics on genome stability.
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Affiliation(s)
- Anna Y Aksenova
- Laboratory of Amyloid Biology, St. Petersburg State University, 199034 St. Petersburg, Russia.
| | - Sergei M Mirkin
- Department of Biology, Tufts University, Medford, MA 02421, USA.
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6
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Harrington L, Pucci F. In medio stat virtus: unanticipated consequences of telomere dysequilibrium. Philos Trans R Soc Lond B Biol Sci 2019; 373:rstb.2016.0444. [PMID: 29335368 PMCID: PMC5784064 DOI: 10.1098/rstb.2016.0444] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/07/2017] [Indexed: 12/13/2022] Open
Abstract
The integrity of chromosome ends, or telomeres, depends on myriad processes that must balance the need to compact and protect the telomeric, G-rich DNA from detection as a double-stranded DNA break, and yet still permit access to enzymes that process, replicate and maintain a sufficient reserve of telomeric DNA. When unable to maintain this equilibrium, erosion of telomeres leads to perturbations at or near the telomeres themselves, including loss of binding by the telomere protective complex, shelterin, and alterations in transcription and post-translational modifications of histones. Although the catastrophic consequences of full telomere de-protection are well described, recent evidence points to other, less obvious perturbations that arise when telomere length equilibrium is altered. For example, critically short telomeres also perturb DNA methylation and histone post-translational modifications at distal sites throughout the genome. In murine stem cells for example, this dysregulated chromatin leads to inappropriate suppression of pluripotency regulator factors such as Nanog. This review summarizes these recent findings, with an emphasis on how these genome-wide, telomere-induced perturbations can have profound consequences on cell function and fate. This article is part of the theme issue ‘Understanding diversity in telomere dynamics’.
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Affiliation(s)
- Lea Harrington
- Wellcome Trust Centre for Cell Biology, School of Biological Sciences, College of Science and Engineering, University of Edinburgh, Mayfield Road, Edinburgh EH9 3JR, UK
| | - Fabio Pucci
- Wellcome Trust Centre for Cell Biology, School of Biological Sciences, College of Science and Engineering, University of Edinburgh, Mayfield Road, Edinburgh EH9 3JR, UK
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7
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Treating Cancer by Targeting Telomeres and Telomerase. Antioxidants (Basel) 2017; 6:antiox6010015. [PMID: 28218725 PMCID: PMC5384178 DOI: 10.3390/antiox6010015] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2016] [Revised: 02/15/2017] [Accepted: 02/16/2017] [Indexed: 12/22/2022] Open
Abstract
Telomerase is expressed in more than 85% of cancer cells. Tumor cells with metastatic potential may have a high telomerase activity, allowing cells to escape from the inhibition of cell proliferation due to shortened telomeres. Human telomerase primarily consists of two main components: hTERT, a catalytic subunit, and hTR, an RNA template whose sequence is complimentary to the telomeric 5′-dTTAGGG-3′ repeat. In humans, telomerase activity is typically restricted to renewing tissues, such as germ cells and stem cells, and is generally absent in normal cells. While hTR is constitutively expressed in most tissue types, hTERT expression levels are low enough that telomere length cannot be maintained, which sets a proliferative lifespan on normal cells. However, in the majority of cancers, telomerase maintains stable telomere length, thereby conferring cell immortality. Levels of hTERT mRNA are directly related to telomerase activity, thereby making it a more suitable therapeutic target than hTR. Recent data suggests that stabilization of telomeric G-quadruplexes may act to indirectly inhibit telomerase action by blocking hTR binding. Telomeric DNA has the propensity to spontaneously form intramolecular G-quadruplexes, four-stranded DNA secondary structures that are stabilized by the stacking of guanine residues in a planar arrangement. The functional roles of telomeric G-quadruplexes are not completely understood, but recent evidence suggests that they can stall the replication fork during DNA synthesis and inhibit telomere replication by preventing telomerase and related proteins from binding to the telomere. Long-term treatment with G-quadruplex stabilizers induces a gradual reduction in the length of the G-rich 3’ end of the telomere without a reduction of the total telomere length, suggesting that telomerase activity is inhibited. However, inhibition of telomerase, either directly or indirectly, has shown only moderate success in cancer patients. Another promising approach of targeting the telomere is the use of guanine-rich oligonucleotides (GROs) homologous to the 3’ telomere overhang sequence (T-oligos). T-oligos, particularly a specific 11-base oligonucleotide (5’-dGTTAGGGTTAG-3’) called T11, have been shown to induce DNA damage responses (DDRs) such as senescence, apoptosis, and cell cycle arrest in numerous cancer cell types with minimal or no cytostatic effects in normal, non-transformed cells. As a result, T-oligos and other GROs are being investigated as prospective anticancer therapeutics. Interestingly, the DDRs induced by T-oligos in cancer cells are similar to the effects seen after progressive telomere degradation in normal cells. The loss of telomeres is an important tumor suppressor mechanism that is commonly absent in transformed malignant cells, and hence, T-oligos have garnered significant interest as a novel strategy to combat cancer. However, little is known about their mechanism of action. In this review, we discuss the current understanding of how T-oligos exert their antiproliferative effects in cancer cells and their role in inhibition of telomerase. We also discuss the current understanding of telomerase in cancer and various therapeutic targets related to the telomeres and telomerase.
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8
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Wood AM, Laster K, Rice EL, Kosak ST. A beginning of the end: new insights into the functional organization of telomeres. Nucleus 2016; 6:172-8. [PMID: 25961132 PMCID: PMC4615733 DOI: 10.1080/19491034.2015.1048407] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Ever since the first demonstration of their repetitive sequence and unique replication pathway, telomeres have beguiled researchers with how they function in protecting chromosome ends. Of course much has been learned over the years, and we now appreciate that telomeres are comprised of the multimeric protein/DNA shelterin complex and that the formation of t-loops provides protection from DNA damage machinery. Deriving their name from D-loops, t-loops are generated by the insertion of the 3′ overhang into telomeric repeats facilitated by the binding of TRF2. Recent studies have uncovered novel forms of chromosome end-structure that may implicate telomere organization in cellular processes beyond its essential role in telomere protection and homeostasis. In particular, we have recently described that t-loops form in a TRF2-dependent manner at interstitial telomere repeat sequences, which we termed interstitial telomere loops (ITLs). These structures are also dependent on association of lamin A/C, a canonical component of the nucleoskeleton that is mutated in myriad human diseases, including human segmental progeroid syndromes. Since ITLs are associated with telomere stability and require functional lamin A/C, our study suggests a mechanistic link between cellular aging (replicative senescence induced by telomere shortening) and organismal aging (modeled by Hutchinson Gilford Progeria Syndrome). Here we speculate on other potential ramifications of ITL formation, from gene expression to genome stability to chromosome structure.
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Affiliation(s)
- Ashley M Wood
- a Department of Cell and Molecular Biology; Feinberg School of Medicine; Northwestern University ; Chicago , IL , USA
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9
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Silva S, Altmannova V, Luke-Glaser S, Henriksen P, Gallina I, Yang X, Choudhary C, Luke B, Krejci L, Lisby M. Mte1 interacts with Mph1 and promotes crossover recombination and telomere maintenance. Genes Dev 2016; 30:700-17. [PMID: 26966248 PMCID: PMC4803055 DOI: 10.1101/gad.276204.115] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2015] [Accepted: 02/17/2016] [Indexed: 11/25/2022]
Abstract
Mph1 is a member of the conserved FANCM family of DNA motor proteins that play key roles in genome maintenance processes underlying Fanconi anemia, a cancer predisposition syndrome in humans. Here, we identify Mte1 as a novel interactor of the Mph1 helicase in Saccharomyces cerevisiae. In vitro, Mte1 (Mph1-associated telomere maintenance protein 1) binds directly to DNA with a preference for branched molecules such as D loops and fork structures. In addition, Mte1 stimulates the helicase and fork regression activities of Mph1 while inhibiting the ability of Mph1 to dissociate recombination intermediates. Deletion of MTE1 reduces crossover recombination and suppresses the sensitivity of mph1Δ mutant cells to replication stress. Mph1 and Mte1 interdependently colocalize at DNA damage-induced foci and dysfunctional telomeres, and MTE1 deletion results in elongated telomeres. Taken together, our data indicate that Mte1 plays a role in regulation of crossover recombination, response to replication stress, and telomere maintenance.
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Affiliation(s)
- Sonia Silva
- Department of Biology, University of Copenhagen, DK-2200 Copenhagen N, Denmark
| | | | | | - Peter Henriksen
- The Novo Nordisk Foundation Center for Protein Research, Faculty of Health Sciences, University of Copenhagen, DK-2200 Copenhagen N, Denmark
| | - Irene Gallina
- Department of Biology, University of Copenhagen, DK-2200 Copenhagen N, Denmark
| | - Xuejiao Yang
- Department of Biology, University of Copenhagen, DK-2200 Copenhagen N, Denmark
| | - Chunaram Choudhary
- The Novo Nordisk Foundation Center for Protein Research, Faculty of Health Sciences, University of Copenhagen, DK-2200 Copenhagen N, Denmark
| | - Brian Luke
- Institute of Molecular Biology gGmbH (IMB), 55128 Mainz, Germany
| | - Lumir Krejci
- Department of Biology, Masaryk University, CZ-62500 Brno, Czech Republic; National Centre for Biomolecular Research, Masaryk University, CZ-62500 Brno, Czech Republic; International Clinical Research Center, St. Anne's University Hospital Brno, CZ-656 91 Brno, Czech Republic; Center for Biomolecular and Cellular Engineering, St. Anne's University Hospital Brno, CZ-656 91 Brno, Czech Republic
| | - Michael Lisby
- Department of Biology, University of Copenhagen, DK-2200 Copenhagen N, Denmark; Center for Chromosome Stability, Department of Cellular and Molecular Medicine, University of Copenhagen, DK-2200 Copenhagen N, Denmark
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10
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Lustig AJ. Hypothesis: Paralog Formation from Progenitor Proteins and Paralog Mutagenesis Spur the Rapid Evolution of Telomere Binding Proteins. Front Genet 2016; 7:10. [PMID: 26904098 PMCID: PMC4748036 DOI: 10.3389/fgene.2016.00010] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Accepted: 01/22/2016] [Indexed: 12/31/2022] Open
Abstract
Through elegant studies in fungal cells and complex organisms, we propose a unifying paradigm for the rapid evolution of telomere binding proteins (TBPs) that associate with either (or both) telomeric DNA and telomeric proteins. TBPs protect and regulate telomere structure and function. Four critical factors are involved. First, TBPs that commonly bind to telomeric DNA include the c-Myb binding proteins, OB-fold single-stranded binding proteins, and G-G base paired Hoogsteen structure (G4) binding proteins. Each contributes independently or, in some cases, cooperatively, to provide a minimum level of telomere function. As a result of these minimal requirements and the great abundance of homologs of these motifs in the proteome, DNA telomere-binding activity may be generated more easily than expected. Second, telomere dysfunction gives rise to genome instability, through the elevation of recombination rates, genome ploidy, and the frequency of gene mutations. The formation of paralogs that diverge from their progenitor proteins ultimately can form a high frequency of altered TBPs with altered functions. Third, TBPs that assemble into complexes (e.g., mammalian shelterin) derive benefits from the novel emergent functions. Fourth, a limiting factor in the evolution of TBP complexes is the formation of mutually compatible interaction surfaces amongst the TBPs. These factors may have different degrees of importance in the evolution of different phyla, illustrated by the apparently simpler telomeres in complex plants. Selective pressures that can utilize the mechanisms of paralog formation and mutagenesis to drive TBP evolution along routes dependent on the requisite physiologic changes.
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Affiliation(s)
- Arthur J Lustig
- Department of Biochemistry and Molecular Biology, Tulane University, New Orleans LA, USA
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11
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Wood AM, Danielsen JMR, Lucas CA, Rice EL, Scalzo D, Shimi T, Goldman RD, Smith ED, Le Beau MM, Kosak ST. TRF2 and lamin A/C interact to facilitate the functional organization of chromosome ends. Nat Commun 2014; 5:5467. [PMID: 25399868 PMCID: PMC4235626 DOI: 10.1038/ncomms6467] [Citation(s) in RCA: 98] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2014] [Accepted: 10/03/2014] [Indexed: 12/28/2022] Open
Abstract
Telomeres protect the ends of linear genomes, and the gradual loss of telomeres is associated with cellular ageing. Telomere protection involves the insertion of the 3' overhang facilitated by telomere repeat-binding factor 2 (TRF2) into telomeric DNA, forming t-loops. We present evidence suggesting that t-loops can also form at interstitial telomeric sequences in a TRF2-dependent manner, forming an interstitial t-loop (ITL). We demonstrate that TRF2 association with interstitial telomeric sequences is stabilized by co-localization with A-type lamins (lamin A/C). We also find that lamin A/C interacts with TRF2 and that reduction in levels of lamin A/C or mutations in LMNA that cause an autosomal dominant premature ageing disorder--Hutchinson Gilford Progeria Syndrome (HGPS)-lead to reduced ITL formation and telomere loss. We propose that cellular and organismal ageing are intertwined through the effects of the interaction between TRF2 and lamin A/C on chromosome structure.
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Affiliation(s)
- Ashley M. Wood
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611, USA
| | | | - Catherine A. Lucas
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611, USA
| | - Ellen L. Rice
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611, USA
| | - David Scalzo
- Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, USA
| | - Takeshi Shimi
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611, USA
| | - Robert D. Goldman
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611, USA
| | - Erica D. Smith
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611, USA
| | - Michelle M. Le Beau
- Section of Hematology/Oncology, Department of Medicine and Comprehensive Cancer Center, The University of Chicago, Chicago, Illinois 60637, USA
| | - Steven T. Kosak
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611, USA
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12
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Malyavko AN, Parfenova YY, Zvereva MI, Dontsova OA. Telomere length regulation in budding yeasts. FEBS Lett 2014; 588:2530-6. [PMID: 24914478 DOI: 10.1016/j.febslet.2014.05.049] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2014] [Revised: 05/23/2014] [Accepted: 05/23/2014] [Indexed: 11/19/2022]
Abstract
Telomeres are the nucleoprotein caps of chromosomes. Their length must be tightly regulated in order to maintain the stability of the genome. This is achieved by the intricate network of interactions between different proteins and protein-RNA complexes. Different organisms use various mechanisms for telomere length homeostasis. However, details of these mechanisms are not yet completely understood. In this review we have summarized our latest achievements in the understanding of telomere length regulation in budding yeasts.
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Affiliation(s)
- Alexander N Malyavko
- Faculty of Chemistry, Lomonosov Moscow State University, 119999 Moscow, Russia; Belozersky Institute, Moscow State University, Leninskie Gory 1, Bldg. 40, 119991 Moscow, Russia
| | - Yuliya Y Parfenova
- Faculty of Chemistry, Lomonosov Moscow State University, 119999 Moscow, Russia; Belozersky Institute, Moscow State University, Leninskie Gory 1, Bldg. 40, 119991 Moscow, Russia
| | - Maria I Zvereva
- Faculty of Chemistry, Lomonosov Moscow State University, 119999 Moscow, Russia; Belozersky Institute, Moscow State University, Leninskie Gory 1, Bldg. 40, 119991 Moscow, Russia
| | - Olga A Dontsova
- Faculty of Chemistry, Lomonosov Moscow State University, 119999 Moscow, Russia; Belozersky Institute, Moscow State University, Leninskie Gory 1, Bldg. 40, 119991 Moscow, Russia.
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Lin J, Kaur P, Countryman P, Opresko PL, Wang H. Unraveling secrets of telomeres: one molecule at a time. DNA Repair (Amst) 2014; 20:142-153. [PMID: 24569170 DOI: 10.1016/j.dnarep.2014.01.012] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2013] [Revised: 01/03/2014] [Accepted: 01/13/2014] [Indexed: 01/23/2023]
Abstract
Telomeres play important roles in maintaining the stability of linear chromosomes. Telomere maintenance involves dynamic actions of multiple proteins interacting with long repetitive sequences and complex dynamic DNA structures, such as G-quadruplexes, T-loops and t-circles. Given the heterogeneity and complexity of telomeres, single-molecule approaches are essential to fully understand the structure-function relationships that govern telomere maintenance. In this review, we present a brief overview of the principles of single-molecule imaging and manipulation techniques. We then highlight results obtained from applying these single-molecule techniques for studying structure, dynamics and functions of G-quadruplexes, telomerase, and shelterin proteins.
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Affiliation(s)
- Jiangguo Lin
- Physics Department, North Carolina State University, Raleigh, NC 27695, USA
| | - Parminder Kaur
- Physics Department, North Carolina State University, Raleigh, NC 27695, USA
| | - Preston Countryman
- Physics Department, North Carolina State University, Raleigh, NC 27695, USA
| | - Patricia L Opresko
- Department of Environmental and Occupational Health, University of Pittsburgh Graduate School of Public Health, Pittsburgh, PA 15219, USA
| | - Hong Wang
- Physics Department, North Carolina State University, Raleigh, NC 27695, USA.
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