1
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Bertrand A, Ba I, Kermasson L, Pirabakaran V, Chable N, Lainey E, Ménard C, Kallel F, Picard C, Hadiji S, Coolen-Allou N, Blanchard E, de Villartay JP, Moshous D, Roelens M, Callebaut I, Kannengiesser C, Revy P. Characterization of novel mutations in the TEL-patch domain of the telomeric factor TPP1 associated with telomere biology disorders. Hum Mol Genet 2024; 33:612-623. [PMID: 38176734 DOI: 10.1093/hmg/ddad210] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Revised: 12/04/2023] [Accepted: 12/13/2023] [Indexed: 01/06/2024] Open
Abstract
Telomeres are nucleoprotein structures that protect the chromosome ends from degradation and fusion. Telomerase is a ribonucleoprotein complex essential to maintain the length of telomeres. Germline defects that lead to short and/or dysfunctional telomeres cause telomere biology disorders (TBDs), a group of rare and heterogeneous Mendelian diseases including pulmonary fibrosis, dyskeratosis congenita, and Høyeraal-Hreidarsson syndrome. TPP1, a telomeric factor encoded by the gene ACD, recruits telomerase at telomere and stimulates its activity via its TEL-patch domain that directly interacts with TERT, the catalytic subunit of telomerase. TBDs due to TPP1 deficiency have been reported only in 11 individuals. We here report four unrelated individuals with a wide spectrum of TBD manifestations carrying either heterozygous or homozygous ACD variants consisting in the recurrent and previously described in-frame deletion of K170 (K170∆) and three novel missense mutations G179D, L184R, and E215V. Structural and functional analyses demonstrated that the four variants affect the TEL-patch domain of TPP1 and impair telomerase activity. In addition, we identified in the ACD gene several motifs associated with small deletion hotspots that could explain the recurrence of the K170∆ mutation. Finally, we detected in a subset of blood cells from one patient, a somatic TERT promoter-activating mutation that likely provides a selective advantage over non-modified cells, a phenomenon known as indirect somatic genetic rescue. Together, our results broaden the genetic and clinical spectrum of TPP1 deficiency and specify new residues in the TEL-patch domain that are crucial for length maintenance and stability of human telomeres in vivo.
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Affiliation(s)
- Alexis Bertrand
- Laboratory of Genome Dynamics in the Immune System, Equipe Labellisée Ligue contre le Cancer, INSERM UMR 1163, Imagine Institute, 24 boulevard du Montparnasse, Paris 75015, France
- Université Paris Cité, Imagine Institute, Paris 75015, France
| | - Ibrahima Ba
- Laboratory of Genome Dynamics in the Immune System, Equipe Labellisée Ligue contre le Cancer, INSERM UMR 1163, Imagine Institute, 24 boulevard du Montparnasse, Paris 75015, France
- Université Paris Cité, Imagine Institute, Paris 75015, France
- Assistance Publique des Hôpitaux de Paris, Hôpital Bichat, Service de Génétique, Université Paris Diderot, Paris 75018, France
| | - Laëtitia Kermasson
- Laboratory of Genome Dynamics in the Immune System, Equipe Labellisée Ligue contre le Cancer, INSERM UMR 1163, Imagine Institute, 24 boulevard du Montparnasse, Paris 75015, France
- Université Paris Cité, Imagine Institute, Paris 75015, France
| | - Vithura Pirabakaran
- Laboratory of Genome Dynamics in the Immune System, Equipe Labellisée Ligue contre le Cancer, INSERM UMR 1163, Imagine Institute, 24 boulevard du Montparnasse, Paris 75015, France
- Université Paris Cité, Imagine Institute, Paris 75015, France
| | - Noémie Chable
- Laboratory of Genome Dynamics in the Immune System, Equipe Labellisée Ligue contre le Cancer, INSERM UMR 1163, Imagine Institute, 24 boulevard du Montparnasse, Paris 75015, France
- Université Paris Cité, Imagine Institute, Paris 75015, France
| | - Elodie Lainey
- Hematology Laboratory, Robert Debré Hospital-AssistancePublique-Hôpitaux de Paris (APHP), INSERM UMR 1131-Hematology University Institute-Denis Diderot School of Medicine, Paris 75019, France
| | - Christelle Ménard
- Assistance Publique des Hôpitaux de Paris, Hôpital Bichat, Service de Génétique, Université Paris Diderot, Paris 75018, France
| | - Faten Kallel
- Hematology Department, Hedi Chaker Hospital, 3029, Sfax, Tunisia
| | - Capucine Picard
- Université Paris Cité, Imagine Institute, Paris 75015, France
- Department of Pediatric Immunology, Hematology and Rheumatology, Necker-Enfants Malades Hospital, (APHP), Paris 75015, France
- Centre de références des déficits immunitaires Héréditaires (CEREDIH), Necker-Enfants Malades Hospital APHP, Paris 75015, France
- Laboratory of Lymphocyte Activation and Susceptibility to EBV infection, Inserm UMR 1163, Institut Imagine, Paris 75015, France
| | - Sondes Hadiji
- Hematology Department, Hedi Chaker Hospital, 3029, Sfax, Tunisia
| | - Nathalie Coolen-Allou
- Service de Pneumologie, Hôpital Félix Guyon, CHU Réunion, Saint-Denis de la Réunion 97400, France
| | - Elodie Blanchard
- Service de Pneumologie, Hôpital Haut-Lévêque, CHU Bordeaux, Bordeaux 33604, France
| | - Jean-Pierre de Villartay
- Laboratory of Genome Dynamics in the Immune System, Equipe Labellisée Ligue contre le Cancer, INSERM UMR 1163, Imagine Institute, 24 boulevard du Montparnasse, Paris 75015, France
- Université Paris Cité, Imagine Institute, Paris 75015, France
| | - Despina Moshous
- Laboratory of Genome Dynamics in the Immune System, Equipe Labellisée Ligue contre le Cancer, INSERM UMR 1163, Imagine Institute, 24 boulevard du Montparnasse, Paris 75015, France
- Université Paris Cité, Imagine Institute, Paris 75015, France
- Department of Pediatric Immunology, Hematology and Rheumatology, Necker-Enfants Malades Hospital, (APHP), Paris 75015, France
| | - Marie Roelens
- Université Paris Cité, Imagine Institute, Paris 75015, France
- Centre de références des déficits immunitaires Héréditaires (CEREDIH), Necker-Enfants Malades Hospital APHP, Paris 75015, France
| | - Isabelle Callebaut
- Sorbonne Université, Muséum National d'Histoire Naturelle, UMR CNRS 7590, Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, IMPMC, Paris 75005, France
| | - Caroline Kannengiesser
- Assistance Publique des Hôpitaux de Paris, Hôpital Bichat, Service de Génétique, Université Paris Diderot, Paris 75018, France
| | - Patrick Revy
- Laboratory of Genome Dynamics in the Immune System, Equipe Labellisée Ligue contre le Cancer, INSERM UMR 1163, Imagine Institute, 24 boulevard du Montparnasse, Paris 75015, France
- Université Paris Cité, Imagine Institute, Paris 75015, France
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2
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Kuan XY, Fauzi NSA, Ng KY, Bakhtiar A. Exploring the Causal Relationship Between Telomere Biology and Alzheimer's Disease. Mol Neurobiol 2023; 60:4169-4183. [PMID: 37046137 PMCID: PMC10293431 DOI: 10.1007/s12035-023-03337-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2022] [Accepted: 04/03/2023] [Indexed: 04/14/2023]
Abstract
Telomeres, also known as the "protective caps" of our chromosomes, shorten with each cell cycle due to the end replication problem. This process, termed telomere attrition, is associated with many age-related disorders, such as Alzheimer's disease (AD). Despite the numerous studies conducted in this field, the role of telomere attrition in the onset of the disease remains unclear. To investigate the causal relationship between short telomeres and AD, this review aims to highlight the primary factors that regulate telomere length and maintain its integrity, with an additional outlook on the role of oxidative stress, which is commonly associated with aging and molecular damage. Although some findings thus far might be contradictory, telomere attrition likely plays a crucial role in the progression of AD due to its close association with oxidative stress. The currently available treatments for AD are only symptomatic without affecting the progression of the disease. The components of telomere biology discussed in this paper have previously been studied as an alternative treatment option for several diseases and have exhibited promising in vitro and in vivo results. Hence, this should provide a basis for future research to develop a potential therapeutic strategy for AD. (Created with BioRender.com).
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Affiliation(s)
- Xi-Yuen Kuan
- School of Pharmacy, Monash University Malaysia, Jalan Lagoon Selatan, 47500, Bandar Sunway, Selangor, Malaysia
| | - Nurul Syahira Ahmad Fauzi
- School of Pharmacy, Monash University Malaysia, Jalan Lagoon Selatan, 47500, Bandar Sunway, Selangor, Malaysia
| | - Khuen Yen Ng
- School of Pharmacy, Monash University Malaysia, Jalan Lagoon Selatan, 47500, Bandar Sunway, Selangor, Malaysia
| | - Athirah Bakhtiar
- School of Pharmacy, Monash University Malaysia, Jalan Lagoon Selatan, 47500, Bandar Sunway, Selangor, Malaysia.
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3
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Lue NF, Autexier C. Orchestrating nucleic acid-protein interactions at chromosome ends: telomerase mechanisms come into focus. Nat Struct Mol Biol 2023; 30:878-890. [PMID: 37400652 PMCID: PMC10539978 DOI: 10.1038/s41594-023-01022-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Accepted: 05/16/2023] [Indexed: 07/05/2023]
Abstract
Telomerase is a special reverse transcriptase ribonucleoprotein dedicated to the synthesis of telomere repeats that protect chromosome ends. Among reverse transcriptases, telomerase is unique in using a stably associated RNA with an embedded template to synthesize a specified sequence. Moreover, it is capable of iteratively copying the same template region (repeat addition processivity) through multiple rounds of RNA-DNA unpairing and reannealing, that is, the translocation reaction. Biochemical analyses of telomerase over the past 3 decades in protozoa, fungi and mammals have identified structural elements that underpin telomerase mechanisms and have led to models that account for the special attributes of telomerase. Notably, these findings and models can now be interpreted and adjudicated through recent cryo-EM structures of Tetrahymena and human telomerase holoenzyme complexes in association with substrates and regulatory proteins. Collectively, these structures reveal the intricate protein-nucleic acid interactions that potentiate telomerase's unique translocation reaction and clarify how this enzyme reconfigures the basic reverse transcriptase scaffold to craft a polymerase dedicated to the synthesis of telomere DNA. Among the many new insights is the resolution of the telomerase 'anchor site' proposed more than 3 decades ago. The structures also highlight the nearly universal conservation of a protein-protein interface between an oligonucleotide/oligosaccharide-binding (OB)-fold regulatory protein and the telomerase catalytic subunit, which enables spatial and temporal regulation of telomerase function in vivo. In this Review, we discuss key features of the structures in combination with relevant functional analyses. We also examine conserved and divergent aspects of telomerase mechanisms as gleaned from studies in different model organisms.
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Affiliation(s)
- Neal F Lue
- Department of Microbiology and Immunology, Weill Cornell Medicine, New York, NY, USA.
| | - Chantal Autexier
- Lady Davis Institute for Medical Research, Jewish General Hospital and Department of Anatomy and Cell Biology and Department of Medicine, McGill University, Montreal, Quebec, Canada.
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4
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Wang H, Ma T, Zhang X, Chen W, Lan Y, Kuang G, Hsu SJ, He Z, Chen Y, Stewart J, Bhattacharjee A, Luo Z, Price C, Feng X. CTC1 OB-B interaction with TPP1 terminates telomerase and prevents telomere overextension. Nucleic Acids Res 2023; 51:4914-4928. [PMID: 37021555 PMCID: PMC10250220 DOI: 10.1093/nar/gkad237] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Revised: 03/16/2023] [Accepted: 03/31/2023] [Indexed: 04/07/2023] Open
Abstract
CST (CTC1-STN1-TEN1) is a telomere associated complex that binds ssDNA and is required for multiple steps in telomere replication, including termination of G-strand extension by telomerase and synthesis of the complementary C-strand. CST contains seven OB-folds which appear to mediate CST function by modulating CST binding to ssDNA and the ability of CST to recruit or engage partner proteins. However, the mechanism whereby CST achieves its various functions remains unclear. To address the mechanism, we generated a series of CTC1 mutants and studied their effect on CST binding to ssDNA and their ability to rescue CST function in CTC1-/- cells. We identified the OB-B domain as a key determinant of telomerase termination but not C-strand synthesis. CTC1-ΔB expression rescued C-strand fill-in, prevented telomeric DNA damage signaling and growth arrest. However, it caused progressive telomere elongation and the accumulation of telomerase at telomeres, indicating an inability to limit telomerase action. The CTC1-ΔB mutation greatly reduced CST-TPP1 interaction but only modestly affected ssDNA binding. OB-B point mutations also weakened TPP1 association, with the deficiency in TPP1 interaction tracking with an inability to limit telomerase action. Overall, our results indicate that CTC1-TPP1 interaction plays a key role in telomerase termination.
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Affiliation(s)
- Huan Wang
- Department of Pediatrics, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, China
- Institute of Precision Medicine, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Tengfei Ma
- Department of Pediatrics, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, China
- Institute of Precision Medicine, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Xiaotong Zhang
- Institute of Precision Medicine, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Wei Chen
- Institute of Precision Medicine, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Yina Lan
- Institute of Precision Medicine, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Guotao Kuang
- Institute of Precision Medicine, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Shih-Jui Hsu
- Department of Cancer Biology, University of Cincinnati, Cincinnati, OH, USA
| | - Zibin He
- MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Yuxi Chen
- MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Jason Stewart
- Department of Biological Sciences, University of South Carolina, Columbia, SC, USA
| | | | - Zhenhua Luo
- Department of Pediatrics, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, China
- Institute of Precision Medicine, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Carolyn Price
- Department of Cancer Biology, University of Cincinnati, Cincinnati, OH, USA
| | - Xuyang Feng
- Department of Pediatrics, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, China
- Institute of Precision Medicine, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, China
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5
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Ackerson SM, Romney C, Schuck PL, Stewart JA. To Join or Not to Join: Decision Points Along the Pathway to Double-Strand Break Repair vs. Chromosome End Protection. Front Cell Dev Biol 2021; 9:708763. [PMID: 34322492 PMCID: PMC8311741 DOI: 10.3389/fcell.2021.708763] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Accepted: 06/17/2021] [Indexed: 01/01/2023] Open
Abstract
The regulation of DNA double-strand breaks (DSBs) and telomeres are diametrically opposed in the cell. DSBs are considered one of the most deleterious forms of DNA damage and must be quickly recognized and repaired. Telomeres, on the other hand, are specialized, stable DNA ends that must be protected from recognition as DSBs to inhibit unwanted chromosome fusions. Decisions to join DNA ends, or not, are therefore critical to genome stability. Yet, the processing of telomeres and DSBs share many commonalities. Accordingly, key decision points are used to shift DNA ends toward DSB repair vs. end protection. Additionally, DSBs can be repaired by two major pathways, namely homologous recombination (HR) and non-homologous end joining (NHEJ). The choice of which repair pathway is employed is also dictated by a series of decision points that shift the break toward HR or NHEJ. In this review, we will focus on these decision points and the mechanisms that dictate end protection vs. DSB repair and DSB repair choice.
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Affiliation(s)
- Stephanie M Ackerson
- Department of Biological Sciences, University of South Carolina, Columbia, SC, United States
| | - Carlan Romney
- Department of Biological Sciences, University of South Carolina, Columbia, SC, United States
| | - P Logan Schuck
- Department of Biological Sciences, University of South Carolina, Columbia, SC, United States
| | - Jason A Stewart
- Department of Biological Sciences, University of South Carolina, Columbia, SC, United States
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6
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Structures of telomerase at several steps of telomere repeat synthesis. Nature 2021; 593:454-459. [PMID: 33981033 DOI: 10.1038/s41586-021-03529-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Accepted: 04/09/2021] [Indexed: 12/14/2022]
Abstract
Telomerase is unique among the reverse transcriptases in containing a noncoding RNA (known as telomerase RNA (TER)) that includes a short template that is used for the processive synthesis of G-rich telomeric DNA repeats at the 3' ends of most eukaryotic chromosomes1. Telomerase maintains genomic integrity, and its activity or dysregulation are critical determinants of human longevity, stem cell renewal and cancer progression2,3. Previous cryo-electron microscopy structures have established the general architecture, protein components and stoichiometries of Tetrahymena and human telomerase, but our understandings of the details of DNA-protein and RNA-protein interactions and of the mechanisms and recruitment involved remain limited4-6. Here we report cryo-electron microscopy structures of active Tetrahymena telomerase with telomeric DNA at different steps of nucleotide addition. Interactions between telomerase reverse transcriptase (TERT), TER and DNA reveal the structural basis of the determination of the 5' and 3' template boundaries, handling of the template-DNA duplex and separation of the product strand during nucleotide addition. The structure and binding interface between TERT and telomerase protein p50 (a homologue of human TPP17,8) define conserved interactions that are required for telomerase activation and recruitment to telomeres. Telomerase La-related protein p65 remodels several regions of TER, bridging the 5' and 3' ends and the conserved pseudoknot to facilitate assembly of the TERT-TER catalytic core.
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7
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Grill S, Padmanaban S, Friedman A, Perkey E, Allen F, Tesmer VM, Chase J, Khoriaty R, Keegan CE, Maillard I, Nandakumar J. TPP1 mutagenesis screens unravel shelterin interfaces and functions in hematopoiesis. JCI Insight 2021; 6:138059. [PMID: 33822766 PMCID: PMC8262337 DOI: 10.1172/jci.insight.138059] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Accepted: 03/31/2021] [Indexed: 02/06/2023] Open
Abstract
Telomerase catalyzes chromosome end replication in stem cells and other long-lived cells. Mutations in telomerase or telomere-related genes result in diseases known as telomeropathies. Telomerase is recruited to chromosome ends by the ACD/TPP1 protein (TPP1 hereafter), a component of the shelterin complex that protects chromosome ends from unwanted end joining. TPP1 facilitates end protection by binding shelterin proteins POT1 and TIN2. TPP1 variants have been associated with telomeropathies but remain poorly characterized in vivo. Disease variants and mutagenesis scans provide efficient avenues to interrogate the distinct physiological roles of TPP1. Here, we conduct mutagenesis in the TIN2- and POT1-binding domains of TPP1 to discover mutations that dissect TPP1's functions. Our results extend current structural data to reveal that the TPP1-TIN2 interface is more extensive than previously thought and highlight the robustness of the POT1-TPP1 interface. Introduction of separation-of-function mutants alongside known TPP1 telomeropathy mutations in mouse hematopoietic stem cells (mHSCs) lacking endogenous TPP1 demonstrated a clear phenotypic demarcation. TIN2- and POT1-binding mutants were unable to rescue mHSC failure resulting from end deprotection. In contrast, TPP1 telomeropathy mutations sustained mHSC viability, consistent with their selectively impacting end replication. These results highlight the power of scanning mutagenesis in revealing structural interfaces and dissecting multifunctional genes.
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Affiliation(s)
- Sherilyn Grill
- Department of Molecular, Cellular, and Developmental Biology
| | | | - Ann Friedman
- Life Sciences Institute,,Department of Internal Medicine
| | - Eric Perkey
- Life Sciences Institute,,Graduate Program in Cellular and Molecular Biology, and,Medical Scientist Training Program, University of Michigan, Ann Arbor, Michigan, USA
| | - Frederick Allen
- Division of Hematology/Oncology, Department of Medicine, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA
| | | | - Jennifer Chase
- Life Sciences Institute,,Graduate Program in Cellular and Molecular Biology, and
| | - Rami Khoriaty
- Department of Internal Medicine,,Department of Cell and Developmental Biology
| | - Catherine E. Keegan
- Department of Pediatrics, and,Department of Human Genetics, University of Michigan, Ann Arbor, Michigan, USA
| | - Ivan Maillard
- Life Sciences Institute,,Department of Internal Medicine,,Division of Hematology/Oncology, Department of Medicine, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA.,Department of Cell and Developmental Biology,,Abramson Family Cancer Research Institute, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA
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8
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Lim CJ, Cech TR. Shaping human telomeres: from shelterin and CST complexes to telomeric chromatin organization. Nat Rev Mol Cell Biol 2021; 22:283-298. [PMID: 33564154 DOI: 10.1038/s41580-021-00328-y] [Citation(s) in RCA: 115] [Impact Index Per Article: 38.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/04/2021] [Indexed: 01/14/2023]
Abstract
The regulation of telomere length in mammals is crucial for chromosome end-capping and thus for maintaining genome stability and cellular lifespan. This process requires coordination between telomeric protein complexes and the ribonucleoprotein telomerase, which extends the telomeric DNA. Telomeric proteins modulate telomere architecture, recruit telomerase to accessible telomeres and orchestrate the conversion of the newly synthesized telomeric single-stranded DNA tail into double-stranded DNA. Dysfunctional telomere maintenance leads to telomere shortening, which causes human diseases including bone marrow failure, premature ageing and cancer. Recent studies provide new insights into telomerase-related interactions (the 'telomere replisome') and reveal new challenges for future telomere structural biology endeavours owing to the dynamic nature of telomere architecture and the great number of structures that telomeres form. In this Review, we discuss recently determined structures of the shelterin and CTC1-STN1-TEN1 (CST) complexes, how they may participate in the regulation of telomere replication and chromosome end-capping, and how disease-causing mutations in their encoding genes may affect specific functions. Major outstanding questions in the field include how all of the telomere components assemble relative to each other and how the switching between different telomere structures is achieved.
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Affiliation(s)
- Ci Ji Lim
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, USA. .,Department of Biochemistry, University of Colorado Boulder, Boulder, CO, USA. .,BioFrontiers Institute, University of Colorado Boulder, Boulder, CO, USA.
| | - Thomas R Cech
- Department of Biochemistry, University of Colorado Boulder, Boulder, CO, USA. .,BioFrontiers Institute, University of Colorado Boulder, Boulder, CO, USA. .,Howard Hughes Medical Institute, University of Colorado Boulder, Boulder, CO, USA.
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9
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FBW7 Mediates Senescence and Pulmonary Fibrosis through Telomere Uncapping. Cell Metab 2020; 32:860-877.e9. [PMID: 33086033 DOI: 10.1016/j.cmet.2020.10.004] [Citation(s) in RCA: 55] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Revised: 07/28/2020] [Accepted: 10/02/2020] [Indexed: 12/19/2022]
Abstract
Tissue stem cells undergo premature senescence under stress, promoting age-related diseases; however, the associated mechanisms remain unclear. Here, we report that in response to radiation, oxidative stress, or bleomycin, the E3 ubiquitin ligase FBW7 mediates cell senescence and tissue fibrosis through telomere uncapping. FBW7 binding to telomere protection protein 1 (TPP1) facilitates TPP1 multisite polyubiquitination and accelerates degradation, triggering telomere uncapping and DNA damage response. Overexpressing TPP1 or inhibiting FBW7 by genetic ablation, epigenetic interference, or peptidomimetic telomere dysfunction inhibitor (TELODIN) reduces telomere uncapping and shortening, expanding the pulmonary alveolar AEC2 stem cell population in mice. TELODIN, synthesized from the seventh β strand blade of FBW7 WD40 propeller domain, increases TPP1 stability, lung respiratory function, and resistance to senescence and fibrosis in animals chronically exposed to environmental stress. Our findings elucidate a pivotal mechanism underlying stress-induced pulmonary epithelial stem cell senescence and fibrosis, providing a framework for aging-related disorder interventions.
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10
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Mir SM, Samavarchi Tehrani S, Goodarzi G, Jamalpoor Z, Asadi J, Khelghati N, Qujeq D, Maniati M. Shelterin Complex at Telomeres: Implications in Ageing. Clin Interv Aging 2020; 15:827-839. [PMID: 32581523 PMCID: PMC7276337 DOI: 10.2147/cia.s256425] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Accepted: 05/18/2020] [Indexed: 12/16/2022] Open
Abstract
Different factors influence the development and control of ageing. It is well known that progressive telomere shorting is one of the molecular mechanisms underlying ageing. The shelterin complex consists of six telomere-specific proteins which are involved in the protection of chromosome ends. More particularly, this vital complex protects the telomeres from degradation, prevents from activation of unwanted repair systems, regulates the activity of telomerase, and has a crucial role in cellular senescent and ageing-related pathologies. This review explores the organization and function of telomeric DNA along with the mechanism of telomeres during ageing, followed by a discussion of the critical role of shelterin components and their changes during ageing.
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Affiliation(s)
- Seyed Mostafa Mir
- Trauma Research Center, AJA University of Medical Sciences, Tehran, Iran.,Student Research Committee, Babol University of Medical Sciences, Babol, Iran.,Cellular and Molecular Biology Research Center, Health Research Institute, Babol University of Medical Sciences, Babol, Iran
| | - Sadra Samavarchi Tehrani
- Department of Clinical Biochemistry, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran.,Student Scientific Research Center, Tehran University of Medical Sciences, Tehran, Iran
| | - Golnaz Goodarzi
- Department of Clinical Biochemistry, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran.,Student Scientific Research Center, Tehran University of Medical Sciences, Tehran, Iran
| | - Zahra Jamalpoor
- Trauma Research Center, AJA University of Medical Sciences, Tehran, Iran
| | - Jahanbakhsh Asadi
- Metabolic Disorders Research Center, Golestan University of Medical Sciences, Gorgan, Iran
| | - Nafiseh Khelghati
- Department of Clinical Biochemistry, School of Medicine, Urmia University of Medical Sciences, Urmia, Iran
| | - Durdi Qujeq
- Student Research Committee, Babol University of Medical Sciences, Babol, Iran.,Cellular and Molecular Biology Research Center, Health Research Institute, Babol University of Medical Sciences, Babol, Iran
| | - Mahmood Maniati
- School of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
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11
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Structural Features of Nucleoprotein CST/Shelterin Complex Involved in the Telomere Maintenance and Its Association with Disease Mutations. Cells 2020; 9:cells9020359. [PMID: 32033110 PMCID: PMC7072152 DOI: 10.3390/cells9020359] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Revised: 01/23/2020] [Accepted: 01/24/2020] [Indexed: 12/29/2022] Open
Abstract
Telomere comprises the ends of eukaryotic linear chromosomes and is composed of G-rich (TTAGGG) tandem repeats which play an important role in maintaining genome stability, premature aging and onsets of many diseases. Majority of the telomere are replicated by conventional DNA replication, and only the last bit of the lagging strand is synthesized by telomerase (a reverse transcriptase). In addition to replication, telomere maintenance is principally carried out by two key complexes known as shelterin (TRF1, TRF2, TIN2, RAP1, POT1, and TPP1) and CST (CDC13/CTC1, STN1, and TEN1). Shelterin protects the telomere from DNA damage response (DDR) and regulates telomere length by telomerase; while, CST govern the extension of telomere by telomerase and C strand fill-in synthesis. We have investigated both structural and biochemical features of shelterin and CST complexes to get a clear understanding of their importance in the telomere maintenance. Further, we have analyzed ~115 clinically important mutations in both of the complexes. Association of such mutations with specific cellular fault unveils the importance of shelterin and CST complexes in the maintenance of genome stability. A possibility of targeting shelterin and CST by small molecule inhibitors is further investigated towards the therapeutic management of associated diseases. Overall, this review provides a possible direction to understand the mechanisms of telomere borne diseases, and their therapeutic intervention.
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Grill S, Tesmer VM, Nandakumar J. The N Terminus of the OB Domain of Telomere Protein TPP1 Is Critical for Telomerase Action. Cell Rep 2019; 22:1132-1140. [PMID: 29386102 DOI: 10.1016/j.celrep.2018.01.012] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2017] [Revised: 12/19/2017] [Accepted: 01/03/2018] [Indexed: 01/15/2023] Open
Abstract
Telomerase recruitment to telomeres and enzymatic processivity are mediated by TPP1, an essential component of telomere integrity and telomerase function. A surface on the OB domain of TPP1 called the TEL patch is critical for TPP1's telomerase-associated functions. Here, we identify a separate region in the N terminus of the OB domain (termed NOB) of TPP1 that, like the TEL patch, is essential for telomerase repeat addition processivity in vitro as well as telomerase recruitment to telomeres and telomere lengthening in cells. Although well-conserved among most mammalian TPP1 homologs, the NOB region in mice is distinct. Swapping the sequence of human NOB into mouse TPP1 allows it to stimulate human telomerase, qualifying NOB as an important determinant of species specificity for TPP1-telomerase interaction. Our studies show that TPP1 NOB is critical for telomerase function and demonstrate that the telomerase interaction surface on TPP1 is more elaborate than previously appreciated.
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Affiliation(s)
- Sherilyn Grill
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Valerie M Tesmer
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Jayakrishnan Nandakumar
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA.
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Bhat GR, Bhat A, Verma S, Sethi I, Shah R, Sharma V, Dar KA, Abrol D, Kaneez S, Kaul S, Ganju R, Kumar R. Association of newly identified genetic variant rs2853677 of TERT with non-small cell lung cancer and leukemia in population of Jammu and Kashmir, India. BMC Cancer 2019; 19:493. [PMID: 31126249 PMCID: PMC6533689 DOI: 10.1186/s12885-019-5685-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Accepted: 05/08/2019] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND Telomere genetics has recently been emerged as an important field in molecular oncology. Various genome-wide association studies in different population groups have revealed that polymorphisms in Telomere maintenance gene (TERT) gene located on 5p15.33 is associated with susceptibility to leukemia and lung cancer risk. However, association of TERT with leukemia and lung cancer risk in north Indian population groups is still unknown. This study observed the association between genetic variant rs2853677 of TERT and leukemia and lung cancer in the state of Jammu and Kashmir, India. METHODS A total of 781 subjects, out of which 381 cases (203 leukemic patients and 178 non-small cell lung cancer patients NSCLC) and 400 healthy controls were recruited for the study. Genetic variant rs2853677of TERT was detected using the real-time and Taqman Chemistry. Hardy-Weinberg Equilibrium was assessed using the chi square test. The allele and genotype- specific risks were estimated as odds ratio with 95% confidence interval. RESULTS We observed that variant rs2853677 was strongly associated with lung cancer and leukemia risk with an odds ratio (OR) =1.8 (1.03-3.2 at 95% CI); p value (adjusted) = 0.03; odds ratio (OR) =2.9 (1.4-5.5.at 95% CI); p value (adjusted) = 0.002, respectively. CONCLUSION The results of this study suggested that rs2853677 of TERT signifies association in multiple cancers and suggests that it can become potential marker for diagnosis of non-small cell lung cancer and leukemia. The study will provide an insight in understanding the genetic etiology and highlights the role of telomere-associated pathways in non-small cell lung cancer and leukemia. However, it would be quite interesting to explore the contribution of this variant in other cancers as well.
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Affiliation(s)
- Gh Rasool Bhat
- Cancer Genetics Research Group, School of Biotechnology, Shri Mata Vaishno Devi University, Katra, India
| | - Amrita Bhat
- Cancer Genetics Research Group, School of Biotechnology, Shri Mata Vaishno Devi University, Katra, India
| | - Sonali Verma
- Cancer Genetics Research Group, School of Biotechnology, Shri Mata Vaishno Devi University, Katra, India
| | - Itty Sethi
- Human Genetics Research Group, School of Biotechnology, Shri Mata Vaishno Devi University, Katra, India
| | - Ruchi Shah
- Human Genetics Research Group, School of Biotechnology, Shri Mata Vaishno Devi University, Katra, India
| | - Varun Sharma
- Human Genetics Research Group, School of Biotechnology, Shri Mata Vaishno Devi University, Katra, India
| | - Khursheed A Dar
- Chest Disease Hospital, Government Medical College, Srinagar, India
| | - Deepak Abrol
- Department of Radiotherapy, Government Medical College, Jammu, India
| | - Subiya Kaneez
- Department of Radiotherapy, Government Medical College, Srinagar, India
| | - Sandeep Kaul
- Department of surgical Oncology, Shri Mata Vaishno Devi Narayana Super speciality hospital, kata, India
| | - Ramesh Ganju
- Department of Pathology, College of Medicine, The OHIO State University, Columbus, USA
| | - Rakesh Kumar
- Cancer Genetics Research Group, School of Biotechnology, Shri Mata Vaishno Devi University, Katra, India.
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Escandell JM, Carvalho ES, Gallo-Fernandez M, Reis CC, Matmati S, Luís IM, Abreu IA, Coulon S, Ferreira MG. Ssu72 phosphatase is a conserved telomere replication terminator. EMBO J 2019; 38:embj.2018100476. [PMID: 30796050 PMCID: PMC6443209 DOI: 10.15252/embj.2018100476] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Revised: 01/21/2019] [Accepted: 01/28/2019] [Indexed: 01/31/2023] Open
Abstract
Telomeres, the protective ends of eukaryotic chromosomes, are replicated through concerted actions of conventional DNA polymerases and elongated by telomerase, but the regulation of this process is not fully understood. Telomere replication requires (Ctc1/Cdc13)‐Stn1‐Ten1, a telomeric ssDNA‐binding complex homologous to RPA. Here, we show that the evolutionarily conserved phosphatase Ssu72 is responsible for terminating the cycle of telomere replication in fission yeast. Ssu72 controls the recruitment of Stn1 to telomeres by regulating Stn1 phosphorylation at Ser74, a residue located within its conserved OB‐fold domain. Consequently, ssu72∆ mutants are defective in telomere replication and exhibit long 3′‐ssDNA overhangs, indicative of defective lagging‐strand DNA synthesis. We also show that hSSU72 regulates telomerase activation in human cells by controlling recruitment of hSTN1 to telomeres. These results reveal a previously unknown yet conserved role for the phosphatase SSU72, whereby this enzyme controls telomere homeostasis by activating lagging‐strand DNA synthesis, thus terminating the cycle of telomere replication.
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Affiliation(s)
| | | | | | - Clara C Reis
- Instituto Gulbenkian de Ciência, Oeiras, Portugal
| | - Samah Matmati
- Equipe Labellisée Ligue, CRCM, CNRS, Inserm, Institut Paoli-Calmettes, Aix-Marseille University, Marseille, France
| | - Inês Matias Luís
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Isabel A Abreu
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Stéphane Coulon
- Equipe Labellisée Ligue, CRCM, CNRS, Inserm, Institut Paoli-Calmettes, Aix-Marseille University, Marseille, France
| | - Miguel Godinho Ferreira
- Instituto Gulbenkian de Ciência, Oeiras, Portugal .,Institute for Research on Cancer and Aging of Nice (IRCAN), INSERM U1081 UMR7284, CNRS, Nice, France
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15
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Okamoto K, Seimiya H. Revisiting Telomere Shortening in Cancer. Cells 2019; 8:cells8020107. [PMID: 30709063 PMCID: PMC6406355 DOI: 10.3390/cells8020107] [Citation(s) in RCA: 90] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2018] [Revised: 01/28/2019] [Accepted: 01/28/2019] [Indexed: 12/21/2022] Open
Abstract
Telomeres, the protective structures of chromosome ends are gradually shortened by each cell division, eventually leading to senescence or apoptosis. Cancer cells maintain the telomere length for unlimited growth by telomerase reactivation or a recombination-based mechanism. Recent genome-wide analyses have unveiled genetic and epigenetic alterations of the telomere maintenance machinery in cancer. While telomerase inhibition reveals that longer telomeres are more advantageous for cell survival, cancer cells often have paradoxically shorter telomeres compared with those found in the normal tissues. In this review, we summarize the latest knowledge about telomere length alterations in cancer and revisit its rationality. Finally, we discuss the potential utility of telomere length as a prognostic biomarker.
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Affiliation(s)
- Keiji Okamoto
- Division of Molecular Biotherapy, Cancer Chemotherapy Center, Japanese Foundation for Cancer Research, Koto-ku, Tokyo 135-8550, Japan.
| | - Hiroyuki Seimiya
- Division of Molecular Biotherapy, Cancer Chemotherapy Center, Japanese Foundation for Cancer Research, Koto-ku, Tokyo 135-8550, Japan.
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Feldman M, Vershinin Z, Goliand I, Elia N, Levy D. The methyltransferase SETD6 regulates Mitotic progression through PLK1 methylation. Proc Natl Acad Sci U S A 2019; 116:1235-1240. [PMID: 30622182 PMCID: PMC6347700 DOI: 10.1073/pnas.1804407116] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Lysine methylation, catalyzed by protein lysine methyltransferases (PKMTs), is a key player in regulating intracellular signaling pathways. However, the role of PKMTs and the methylation of nonhistone proteins during the cell cycle are largely unexplored. In a recent proteomic screen, we identified that the PKMT SETD6 methylates PLK1-a key regulator of mitosis and highly expressed in tumor cells. In this study, we provide evidence that SETD6 is involved in cell cycle regulation. SETD6-deficient cells were observed to progress faster through the different mitotic steps toward the cytokinesis stage. Mechanistically, we found that during mitosis SETD6 binds and methylates PLK1 on two lysine residues: K209 and K413. Lack of methylation of these two residues results in increased kinase activity of PLK1, leading to accelerated mitosis and faster cellular proliferation, similarly to SETD6-deficient cells. Taken together, our findings reveal a role for SETD6 in regulating mitotic progression, suggesting a pathway through which SETD6 methylation activity contributes to normal mitotic pace.
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Affiliation(s)
- Michal Feldman
- The Shraga Segal Department of Microbiology, Immunology and Genetics, Ben-Gurion University of the Negev, 84105 Be'er-Sheva, Israel;
- The National Institute for Biotechnology in the Negev, Ben-Gurion University of the Negev, 84105 Be'er-Sheva, Israel
| | - Zlata Vershinin
- The Shraga Segal Department of Microbiology, Immunology and Genetics, Ben-Gurion University of the Negev, 84105 Be'er-Sheva, Israel
- The National Institute for Biotechnology in the Negev, Ben-Gurion University of the Negev, 84105 Be'er-Sheva, Israel
| | - Inna Goliand
- The National Institute for Biotechnology in the Negev, Ben-Gurion University of the Negev, 84105 Be'er-Sheva, Israel
- Department of Life Sciences, Ben-Gurion University of the Negev, 84105 Be'er-Sheva, Israel
| | - Natalie Elia
- The National Institute for Biotechnology in the Negev, Ben-Gurion University of the Negev, 84105 Be'er-Sheva, Israel
- Department of Life Sciences, Ben-Gurion University of the Negev, 84105 Be'er-Sheva, Israel
| | - Dan Levy
- The Shraga Segal Department of Microbiology, Immunology and Genetics, Ben-Gurion University of the Negev, 84105 Be'er-Sheva, Israel;
- The National Institute for Biotechnology in the Negev, Ben-Gurion University of the Negev, 84105 Be'er-Sheva, Israel
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17
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Puterman E, Weiss J, Lin J, Schilf S, Slusher AL, Johansen KL, Epel ES. Aerobic exercise lengthens telomeres and reduces stress in family caregivers: A randomized controlled trial - Curt Richter Award Paper 2018. Psychoneuroendocrinology 2018; 98:245-252. [PMID: 30266522 DOI: 10.1016/j.psyneuen.2018.08.002] [Citation(s) in RCA: 61] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Accepted: 08/01/2018] [Indexed: 12/14/2022]
Abstract
STUDY DESIGN Family members caring for chronically ill relatives are typically sedentary, chronically stressed, and at high risk of disease. Observational reports suggest caregivers have accelerated cellular aging as indicated by shorter leukocyte telomere lengths. We performed a randomized controlled trial to examine the effect of aerobic exercise on changes in telomerase levels (primary outcome) and telomere lengths (secondary outcome) in inactive caregivers. METHODS 68 female and male community dwelling dementia caregivers who reported high stress and physical inactivity were randomly assigned to a highly supervised aerobic exercise intervention vs. waitlist control group for 24 weeks. Average leukocyte telomere lengths and peripheral blood mononuclear cells' telomerase activity were measured pre- and post-intervention. All staff completing blood draws, fitness testing and bioassays were blinded to group assignment. RESULTS The intervention group completed approximately 40 min of aerobic exercise 3-5 times per week, verified by actigraphy. There was high (81%) adherence to 120 min/week of aerobic exercise. Groups did not significantly differ in telomerase activity changes across time, but had significant different telomere length changes across time (67.3 base pairs, 95%CI 3.1, 131.5). There were also significant reductions in body mass index and perceived stress and an increase in cardiorespiratory fitness (i.e., VO2peak) in the exercising caregivers versus controls. CONCLUSION In the context of a highly controlled intervention, exercise can induce apparent telomere lengthening, though the mechanisms remain elusive. Our study underscores the importance of increasing participation in aerobic exercise to improve markers of health and attenuate cellular aging in high-risk samples.
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Affiliation(s)
- Eli Puterman
- School of Kinesiology, University of British Columbia, 210-6081 University Boulevard, Vancouver, BC, V6T 1Z1, Canada.
| | - Jordan Weiss
- Population Studies Center, University of Pennsylvania, United States
| | - Jue Lin
- Department of Biochemistry and Biophysics, University of California, San Francisco, United States
| | - Samantha Schilf
- Department of Psychiatry, University of California, San Francisco, United States
| | - Aaron L Slusher
- School of Kinesiology, University of Michigan, United States
| | - Kirsten L Johansen
- Department of Medicine, University of California, San Francisco, United States
| | - Elissa S Epel
- Department of Psychiatry, University of California, San Francisco, United States
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18
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Influence of aging in the modulation of epigenetic biomarkers of carcinogenesis after exposure to air pollution. Exp Gerontol 2018; 110:125-132. [DOI: 10.1016/j.exger.2018.05.018] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2018] [Revised: 05/11/2018] [Accepted: 05/25/2018] [Indexed: 11/19/2022]
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19
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CTC1-STN1 terminates telomerase while STN1-TEN1 enables C-strand synthesis during telomere replication in colon cancer cells. Nat Commun 2018; 9:2827. [PMID: 30026550 PMCID: PMC6053418 DOI: 10.1038/s41467-018-05154-z] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2017] [Accepted: 06/07/2018] [Indexed: 01/20/2023] Open
Abstract
Telomerase elongates the telomeric G-strand to prevent telomere shortening through conventional DNA replication. However, synthesis of the complementary C-strand by DNA polymerase α is also required to maintain telomere length. Polymerase α cannot perform this role without the ssDNA binding complex CST (CTC1-STN1-TEN1). Here we describe the roles of individual CST subunits in telomerase regulation and G-overhang maturation in human colon cancer cells. We show that CTC1-STN1 limits telomerase action to prevent G-overhang overextension. CTC1-/- cells exhibit telomeric DNA damage and growth arrest due to overhang elongation whereas TEN1-/- cells do not. However, TEN1 is essential for C-strand synthesis and TEN1-/- cells exhibit progressive telomere shortening. DNA binding analysis indicates that CTC1-STN1 retains affinity for ssDNA but TEN1 stabilizes binding. We propose CTC1-STN1 binding is sufficient to terminate telomerase action but altered DNA binding dynamics renders CTC1-STN1 unable to properly engage polymerase α on the overhang for C-strand synthesis.
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20
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Armstrong CA, Tomita K. Fundamental mechanisms of telomerase action in yeasts and mammals: understanding telomeres and telomerase in cancer cells. Open Biol 2018; 7:rsob.160338. [PMID: 28330934 PMCID: PMC5376709 DOI: 10.1098/rsob.160338] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Accepted: 02/20/2017] [Indexed: 12/12/2022] Open
Abstract
Aberrant activation of telomerase occurs in 85–90% of all cancers and underpins the ability of cancer cells to bypass their proliferative limit, rendering them immortal. The activity of telomerase is tightly controlled at multiple levels, from transcriptional regulation of the telomerase components to holoenzyme biogenesis and recruitment to the telomere, and finally activation and processivity. However, studies using cancer cell lines and other model systems have begun to reveal features of telomeres and telomerase that are unique to cancer. This review summarizes our current knowledge on the mechanisms of telomerase recruitment and activation using insights from studies in mammals and budding and fission yeasts. Finally, we discuss the differences in telomere homeostasis between normal cells and cancer cells, which may provide a foundation for telomere/telomerase targeted cancer treatments.
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Affiliation(s)
- Christine A Armstrong
- Chromosome Maintenance Group, UCL Cancer Institute, University College London, 72 Huntley Street, London WC1E 6DD, UK
| | - Kazunori Tomita
- Chromosome Maintenance Group, UCL Cancer Institute, University College London, 72 Huntley Street, London WC1E 6DD, UK
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21
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Stewart JA, Wang Y, Ackerson SM, Schuck PL. Emerging roles of CST in maintaining genome stability and human disease. Front Biosci (Landmark Ed) 2018; 23:1564-1586. [PMID: 29293451 DOI: 10.2741/4661] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The human CTC1-STN1-TEN1 (CST) complex is a single-stranded DNA binding protein that shares homology with RPA and interacts with DNA polymerase alpha/primase. CST complexes are conserved from yeasts to humans and function in telomere maintenance. A common role of CST across species is in the regulation of telomere extension by telomerase and C-strand fill-in synthesis. However, recent studies also indicate that CST promotes telomere duplex replication as well the rescue of stalled DNA replication at non-telomeric sites. Furthermore, CST dysfunction and mutation is associated with several genetic diseases and cancers. In this review, we will summarize what is known about CST with a particular focus on the emerging roles of CST in DNA replication and human disease.
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Affiliation(s)
- Jason A Stewart
- Department of Biological Sciences, University of South Carolina, Columbia, SC 29208, USA,
| | - Yilin Wang
- Department of Biological Sciences, University of South Carolina, Columbia, SC 29208, USA
| | - Stephanie M Ackerson
- Department of Biological Sciences, University of South Carolina, Columbia, SC 29208, USA
| | - Percy Logan Schuck
- Department of Biological Sciences, University of South Carolina, Columbia, SC 29208, USA
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22
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Liu Y, Liu F, Cao Y, Xu H, Wu Y, Wu S, Liu D, Zhao Y, Songyang Z, Ma W. Shwachman-Diamond Syndrome Protein SBDS Maintains Human Telomeres by Regulating Telomerase Recruitment. Cell Rep 2018; 22:1849-1860. [PMID: 29444436 PMCID: PMC5844287 DOI: 10.1016/j.celrep.2018.01.057] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2017] [Revised: 12/20/2017] [Accepted: 01/19/2018] [Indexed: 01/15/2023] Open
Abstract
Shwachman-Diamond syndrome (SDS) is a rare pediatric disease characterized by various systemic disorders, including hematopoietic dysfunction. The mutation of Shwachman-Bodian-Diamond syndrome (SBDS) gene has been proposed to be a major causative reason for SDS. Although SBDS patients were reported to have shorter telomere length in granulocytes, the underlying mechanism is still unclear. Here we provide data to elucidate the role of SBDS in telomere protection. We demonstrate that SBDS deficiency leads to telomere shortening. We found that overexpression of disease-associated SBDS mutants or knockdown of SBDS hampered the recruitment of telomerase onto telomeres, while the overall reverse transcriptase activity of telomerase remained unaffected. Moreover, we show that SBDS could specifically bind to TPP1 during the S phase of cell cycle, likely functioning as a stabilizer for TPP1-telomerase interaction. Our findings suggest that SBDS is a telomere-protecting protein that participates in regulating telomerase recruitment.
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Affiliation(s)
- Yi Liu
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Oncology in South China, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Feng Liu
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Oncology in South China, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China.
| | - Yizhao Cao
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Oncology in South China, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Huimin Xu
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Oncology in South China, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Yangxiu Wu
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Oncology in South China, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Su Wu
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Oncology in South China, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Dan Liu
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
| | - Yong Zhao
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Oncology in South China, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Zhou Songyang
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Oncology in South China, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China; Collaborative Innovation Center for Cancer Medicine, Institute of Healthy Aging Research, Sun Yat-sen University, Guangzhou 510006, China; Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA.
| | - Wenbin Ma
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Oncology in South China, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China; Collaborative Innovation Center for Cancer Medicine, Institute of Healthy Aging Research, Sun Yat-sen University, Guangzhou 510006, China.
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Scott H, Kim JK, Yu C, Huang L, Qiao F, Taylor DJ. Spatial Organization and Molecular Interactions of the Schizosaccharomyces pombe Ccq1-Tpz1-Poz1 Shelterin Complex. J Mol Biol 2017; 429:2863-2872. [PMID: 28807855 DOI: 10.1016/j.jmb.2017.08.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2017] [Revised: 07/31/2017] [Accepted: 08/05/2017] [Indexed: 12/18/2022]
Abstract
The shelterin complex is a macromolecular assembly of proteins that binds to and protects telomeric DNA, which composes the ends of all linear chromosomes. Shelterin proteins prevent chromosome ends from fusing together and from eliciting erroneous induction of DNA damage response pathways. In addition, shelterin proteins play key roles in regulating the recruitment and activation of telomerase, an enzyme that extends telomeric DNA. In fission yeast, Schizosaccharomyces pombe, interactions between the shelterin proteins Ccq1, Tpz1, and Poz1 are important for regulating telomerase-mediated telomere synthesis and thus telomere length homeostasis. Here, we used electron microscopy combined with genetic labeling to define the three-dimensional arrangement of the S. pombe Ccq1-Tpz1-Poz1 (CTP) complex. Crosslinking mass spectrometry was used to identify individual residues that are in proximity to the protein-protein interfaces of the assembled CTP complex. Together, our data provide a first glimpse into the architectural design of the CTP complex and reveals unique interactions that are important in maintaining the S. pombe telomere in a non-extendible state.
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Affiliation(s)
- Harry Scott
- Department of Pharmacology, Case Western Reserve University, Cleveland, OH 44106, United States
| | - Jin-Kwang Kim
- Department of Biological Chemistry, University of California Irvine, Irvine, CA 92697, United States
| | - Clinton Yu
- Department of Physiology and Biophysics, University of California Irvine, Irvine, CA 92697, United States
| | - Lan Huang
- Department of Physiology and Biophysics, University of California Irvine, Irvine, CA 92697, United States
| | - Feng Qiao
- Department of Biological Chemistry, University of California Irvine, Irvine, CA 92697, United States.
| | - Derek J Taylor
- Department of Pharmacology, Case Western Reserve University, Cleveland, OH 44106, United States; Department of Biochemistry, Case Western Reserve University, Cleveland, OH 44106, United States.
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Hapangama DK, Kamal A, Saretzki G. Implications of telomeres and telomerase in endometrial pathology. Hum Reprod Update 2017; 23:166-187. [PMID: 27979878 PMCID: PMC5850744 DOI: 10.1093/humupd/dmw044] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Accepted: 12/02/2016] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Eukaryotic chromosomal ends are linear and are protected by nucleoprotein complexes known as telomeres. The complex structural anatomy and the diverse functions of telomeres as well as the unique reverse transcriptase enzyme, telomerase that maintains telomeres are under intensive scientific scrutiny. Both are involved in many human diseases including cancer, but also in ageing and chronic disease such as diabetes. Their intricate involvement in many cellular processes and pathways is being dynamically deciphered in many organs including the endometrium. This review summarizes our current knowledge on the topic of telomeres and telomerase and their potential role in providing plausible explanations for endometrial aberrations related to common gynaecological pathologies. OBJECTIVE AND RATIONALE This review outlines the recent major findings in telomere and telomerase functions in the context of endometrial biology. It highlights the contemporary discoveries in hormonal regulation, normal endometrial regeneration, stem cells and common gynaecological diseases such as endometriosis, infertility, recurrent reproductive failure and endometrial cancer (EC). SEARCH METHODS The authors carried out systematic PubMed (Medline) and Ovid searches using the key words: telomerase, telomeres, telomere length, human telomerase reverse transcriptase, telomeric RNA component, with endometrium, hormonal regulation, endometrial stem/progenitor cells, endometrial regeneration, endometriosis, recurrent miscarriage, infertility, endometrial hyperplasia, EC and uterine cancer. Publications used in this review date from 1995 until 31st June 2016. OUTCOMES The human endometrium is a unique somatic organ, which displays dynamic telomerase activity (TA) related to the menstrual cycle. Telomerase is implicated in almost all endometrial pathologies and appears to be crucial to endometrial stem cells. In particular, it is vital for normal endometrial regeneration, providing a distinct route to formulate possible curative, non-hormonal therapies to treat chronic endometrial conditions. Furthermore, our current understanding of telomere maintenance in EC is incomplete. Data derived from other malignancies on the role of telomerase in carcinogenesis cannot be extrapolated to EC because unlike in other cancers, TA is already present in proliferating healthy endometrial cells. WIDER IMPLICATIONS Since telomerase is pivotal to endometrial regeneration, further studies elucidating the role of telomeres, telomerase, their associated proteins and their regulation in normal endometrial regeneration as well as their role in endometrial pathologies are essential. This approach may allow future development of novel treatment strategies that are not only non-hormonal but also potentially curative.
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Affiliation(s)
- D K Hapangama
- Department of Women's and Children's Health, Institute of Translational Medicine, University of Liverpool, Liverpool, L8 7SS, UK.,Liverpool Women's Hospital NHS Foundation Trust, Crown Street, Liverpool L8 7SS, UK
| | - A Kamal
- Department of Women's and Children's Health, Institute of Translational Medicine, University of Liverpool, Liverpool, L8 7SS, UK.,The National Center for Early Detection of Cancer, Oncology Teaching Hospital, Baghdad Medical City, Baghdad, Iraq
| | - G Saretzki
- Institute for Ageing and Institute for Cell and Molecular Biosciences, Campus for Ageing and Vitality, Newcastle University, Newcastle upon Tyne, NE4 5PL, UK
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25
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Ahmad T, Sundar IK, Tormos AM, Lerner CA, Gerloff J, Yao H, Rahman I. Shelterin Telomere Protection Protein 1 Reduction Causes Telomere Attrition and Cellular Senescence via Sirtuin 1 Deacetylase in Chronic Obstructive Pulmonary Disease. Am J Respir Cell Mol Biol 2017; 56:38-49. [PMID: 27559927 DOI: 10.1165/rcmb.2016-0198oc] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Lung cellular senescence and inflammatory response are the key events in the pathogenesis of chronic obstructive pulmonary disease (COPD) when cigarette smoke (CS) is the main etiological factor. Telomere dysfunction is induced by either critical shortening or disruption of the shelterin complex, leading to cellular senescence. However, it remains unknown whether disruption of the shelterin complex is responsible for CS-induced lung cellular senescence. Here we show that telomere protection protein 1 (TPP1) levels are reduced on telomeres in lungs from mice with emphysema, as well as in lungs from smokers and from patients with COPD. This is associated with persistent telomeric DNA damage, leading to cellular senescence. CS disrupts the interaction of TPP1 with the Sirtuin 1 (Sirt1) complex, leading to increased TPP1 acetylation and degradation. Lung fibroblasts deficient in Sirt1 or treated with a selective Sirt1 inhibitor exhibit increased cellular senescence and decreased TPP1 levels, whereas Sirt1 overexpression and pharmacological activation protect against CS-induced TPP1 reduction and telomeric DNA damage. Our findings support an essential role of TPP1 in protecting CS-induced telomeric DNA damage and cellular senescence, and therefore provide a rationale for a potential therapy for COPD, on the basis of the shelterin complex, in attenuating cellular senescence.
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Affiliation(s)
- Tanveer Ahmad
- Department of Environmental Medicine, University of Rochester Medical Center, Rochester, New York
| | - Isaac K Sundar
- Department of Environmental Medicine, University of Rochester Medical Center, Rochester, New York
| | - Ana M Tormos
- Department of Environmental Medicine, University of Rochester Medical Center, Rochester, New York
| | - Chad A Lerner
- Department of Environmental Medicine, University of Rochester Medical Center, Rochester, New York
| | - Janice Gerloff
- Department of Environmental Medicine, University of Rochester Medical Center, Rochester, New York
| | - Hongwei Yao
- Department of Environmental Medicine, University of Rochester Medical Center, Rochester, New York
| | - Irfan Rahman
- Department of Environmental Medicine, University of Rochester Medical Center, Rochester, New York
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26
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Rice C, Shastrula PK, Kossenkov AV, Hills R, Baird DM, Showe LC, Doukov T, Janicki S, Skordalakes E. Structural and functional analysis of the human POT1-TPP1 telomeric complex. Nat Commun 2017; 8:14928. [PMID: 28393830 PMCID: PMC5394233 DOI: 10.1038/ncomms14928] [Citation(s) in RCA: 78] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Accepted: 02/14/2017] [Indexed: 12/15/2022] Open
Abstract
POT1 and TPP1 are part of the shelterin complex and are essential for telomere length regulation and maintenance. Naturally occurring mutations of the telomeric POT1-TPP1 complex are implicated in familial glioma, melanoma and chronic lymphocytic leukaemia. Here we report the atomic structure of the interacting portion of the human telomeric POT1-TPP1 complex and suggest how several of these mutations contribute to malignant cancer. The POT1 C-terminus (POT1C) forms a bilobal structure consisting of an OB-fold and a holiday junction resolvase domain. TPP1 consists of several loops and helices involved in extensive interactions with POT1C. Biochemical data shows that several of the cancer-associated mutations, partially disrupt the POT1-TPP1 complex, which affects its ability to bind telomeric DNA efficiently. A defective POT1-TPP1 complex leads to longer and fragile telomeres, which in turn promotes genomic instability and cancer.
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Affiliation(s)
- Cory Rice
- The Wistar Institute, 3601 Spruce St, Philadelphia, Pennsylvania 19104, USA
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | | | | | - Robert Hills
- The Wistar Institute, 3601 Spruce St, Philadelphia, Pennsylvania 19104, USA
| | - Duncan M. Baird
- Division of Cancer and Genetics, School of Medicine, Cardiff University, Heath Park, Cardiff CF10 3AT, UK
| | - Louise C. Showe
- The Wistar Institute, 3601 Spruce St, Philadelphia, Pennsylvania 19104, USA
| | - Tzanko Doukov
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Stanford University, Menlo Park, California 94025, USA
| | - Susan Janicki
- The Wistar Institute, 3601 Spruce St, Philadelphia, Pennsylvania 19104, USA
| | - Emmanuel Skordalakes
- The Wistar Institute, 3601 Spruce St, Philadelphia, Pennsylvania 19104, USA
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
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27
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Sethi I, Bhat GR, Singh V, Kumar R, Bhanwer AJS, Bamezai RNK, Sharma S, Rai E. Role of telomeres and associated maintenance genes in Type 2 Diabetes Mellitus: A review. Diabetes Res Clin Pract 2016; 122:92-100. [PMID: 27816684 DOI: 10.1016/j.diabres.2016.10.015] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Revised: 10/09/2016] [Accepted: 10/16/2016] [Indexed: 02/07/2023]
Abstract
Type 2 Diabetes Mellitus (T2DM), a multifactorial complex disorder, is emerging as a major cause of morbidity, mortality and socio-economic burden across the world. Despite huge efforts in understanding genetics of T2DM, only ∼10% of the genetic factors have been identified so far. Telomere attrition, a natural phenomenon has recently emerged in understanding the pathophysiology of T2DM. It has been indicated that Telomeres and associated pathways might be the critical components in the disease etiology, though the mechanism(s) involved are not clear. Recent Genome Wide (GWAS) and Candidate Gene Case-Control Association Studies have also indicated an association of Telomere and associated pathways related genes with T2DM. Single Nucleotide Polymorphisms (SNPs) in the telomere maintenance genes: TERT, TERC, TNKS, CSNK2A2, TEP1, ACD, TRF1 and TRF2, have shown strong association with telomere attrition in T2DM and its pathophysiology, in these studies. However, the assessment has been made within limited ethnicities (Caucasians, Han Chinese cohort and Punjabi Sikhs from South Asia), warranting the study of such associations in different ethnic groups. Here, we propose the possible mechanisms, in the light of existing knowledge, to understand the association of T2DM with telomeres and associated pathways.
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Affiliation(s)
- Itty Sethi
- Human Genetics Research Group, Department of Biotechnology, Shri Mata Vaishno Devi University Katra, J&K 182320, India
| | - G R Bhat
- Human Genetics Research Group, Department of Biotechnology, Shri Mata Vaishno Devi University Katra, J&K 182320, India
| | - Vinod Singh
- Human Genetics Research Group, Department of Biotechnology, Shri Mata Vaishno Devi University Katra, J&K 182320, India
| | - Rakesh Kumar
- Human Genetics Research Group, Department of Biotechnology, Shri Mata Vaishno Devi University Katra, J&K 182320, India
| | - A J S Bhanwer
- Department of Human Genetics, Guru Nanak Dev University, Amritsar, Punjab 143005, India
| | - Rameshwar N K Bamezai
- National Centre of Applied Human Genetics, School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| | - Swarkar Sharma
- Human Genetics Research Group, Department of Biotechnology, Shri Mata Vaishno Devi University Katra, J&K 182320, India.
| | - Ekta Rai
- Human Genetics Research Group, Department of Biotechnology, Shri Mata Vaishno Devi University Katra, J&K 182320, India.
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28
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MTV, an ssDNA Protecting Complex Essential for Transposon-Based Telomere Maintenance in Drosophila. PLoS Genet 2016; 12:e1006435. [PMID: 27835648 PMCID: PMC5105952 DOI: 10.1371/journal.pgen.1006435] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Accepted: 10/20/2016] [Indexed: 12/25/2022] Open
Abstract
Multiple complexes protect telomeres. In telomerase-maintained organisms, Shelterin related complexes occupy the duplex region while the CST and Tpp1-Pot1 complexes bind the single stranded overhang of telomeres. Drosophila uses a transposon-based mechanism for end protection. We showed that the HOAP-HipHop complex occupies the duplex region. Whether an ssDNA-binding complex exists is not known. Here we discover a novel protein, Tea, that is specifically enriched at telomeres to prevent telomere fusion. We also identify a complex consisting of Tea and two known capping proteins, Ver and Moi. The Moi-Tea-Ver (MTV) complex purified in vitro binds and protects ssDNA in a sequence-independent manner. Tea recruits Ver and Moi to telomeres, and point mutations disrupting MTV interaction in vitro result in telomere uncapping, consistent with these proteins functioning as a complex in vivo. MTV thus shares functional similarities with CST or TPP1-POT1 in protecting ssDNA, highlighting a conserved feature in end protecting mechanisms. Chromosome ends are protected by the telomere structure maintained by the telomerase enzyme in most organisms. The fruit fly Drosophila has fascinated the field as the only major model organism that relies solely on a telomerase-independent mechanism for end protection. The fly model is arguably the best system to reveal the most basic features of the telomere. Here we characterize the MTV complex in flies and suggest that MTV fulfills similar function as the ssDNA-binding complexes in other organisms. This is striking considering that MTV subunits display highly accelerated rates of protein evolution. Our findings will be of interest to scientists interested in the molecular mechanisms of telomere protection and evolution biologists interested in how telomere and telomeric functions evolve.
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29
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Lloyd NR, Dickey TH, Hom RA, Wuttke DS. Tying up the Ends: Plasticity in the Recognition of Single-Stranded DNA at Telomeres. Biochemistry 2016; 55:5326-40. [PMID: 27575340 PMCID: PMC5656232 DOI: 10.1021/acs.biochem.6b00496] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Telomeres terminate nearly exclusively in single-stranded DNA (ssDNA) overhangs comprised of the G-rich 3' end. This overhang varies widely in length from species to species, ranging from just a few bases to several hundred nucleotides. These overhangs are not merely a remnant of DNA replication but rather are the result of complex further processing. Proper management of the telomeric overhang is required both to deter the action of the DNA damage machinery and to present the ends properly to the replicative enzyme telomerase. This Current Topic addresses the biochemical and structural features used by the proteins that manage these variable telomeric overhangs. The Pot1 protein tightly binds the single-stranded overhang, preventing DNA damage sensors from binding. Pot1 also orchestrates the access of telomerase to that same substrate. The remarkable plasticity of the binding interface exhibited by the Schizosaccharomyces pombe Pot1 provides mechanistic insight into how these roles may be accomplished, and disease-associated mutations clustered around the DNA-binding interface in the hPOT1 highlight the importance of this function. The budding yeast Cdc13-Stn1-Ten1, a telomeric RPA complex closely associated with telomere function, also interacts with ssDNA in a fashion that allows degenerate sequences to be recognized. A related human complex composed of hCTC1, hSTN1, and hTEN1 has recently emerged with links to both telomere maintenance and general DNA replication and also exhibits mutations associated with telomere pathologies. Overall, these sequence-specific ssDNA binders exhibit a range of recognition properties that allow them to perform their unique biological functions.
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Affiliation(s)
- Neil R. Lloyd
- Department of Chemistry and Biochemistry, 596 UCB, University of Colorado Boulder, Boulder, CO 80309-0596, USADepartment of Chemistry and Biochemistry, 596 UCB, University of Colorado Boulder, Boulder, CO 80309, USA
| | | | - Robert A. Hom
- Department of Chemistry and Biochemistry, 596 UCB, University of Colorado Boulder, Boulder, CO 80309-0596, USADepartment of Chemistry and Biochemistry, 596 UCB, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Deborah S. Wuttke
- Department of Chemistry and Biochemistry, 596 UCB, University of Colorado Boulder, Boulder, CO 80309-0596, USADepartment of Chemistry and Biochemistry, 596 UCB, University of Colorado Boulder, Boulder, CO 80309, USA
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30
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Rajavel M, Orban T, Xu M, Hernandez-Sanchez W, de la Fuente M, Palczewski K, Taylor DJ. Dynamic peptides of human TPP1 fulfill diverse functions in telomere maintenance. Nucleic Acids Res 2016; 44:10467-10479. [PMID: 27655633 PMCID: PMC5137443 DOI: 10.1093/nar/gkw846] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Revised: 09/12/2016] [Accepted: 09/14/2016] [Indexed: 12/12/2022] Open
Abstract
Telomeres are specialized nucleoprotein complexes that comprise the ends of linear chromosomes. Human telomeres end in a short, single-stranded DNA (ssDNA) overhang that is recognized and bound by two telomere proteins, POT1 and TPP1. Whereas POT1 binds directly to telomere ssDNA, its interaction with TPP1 is essential for localization of POT1 to the telomere. TPP1 also provides enhanced binding and sequence discrimination that regulates POT1-TPP1 interactions exclusively with telomere ssDNA. Finally, TPP1 recruits telomerase, the enzyme responsible for synthesis of telomere DNA, to the telomere. While the oligosaccharide-oligonucleotide-binding (OB)-fold domain of TPP1 has been solved by X-ray crystallography, the molecular interactions within the POT1-TPP1-ssDNA ternary complex and the conformational changes that contribute to its diverse functions remain ambiguous. We employed hydrogen/deuterium exchange combined with mass spectrometry to identify three peptides, all residing within the OB-fold of TPP1, that exhibit altered exchange rates upon complex formation or ssDNA binding. Mutation of these regions combined with functional assays revealed the diverse contributions of each moiety in protein-protein interactions, regulating telomerase activity or DNA-binding. Together, these functional data combined with biophysical analyses and homology modeling provide a molecular understanding of the diverse contributions of TPP1 in telomere maintenance.
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Affiliation(s)
- Malligarjunan Rajavel
- Department of Pharmacology, Case Western Reserve University, School of Medicine, Cleveland, OH 44106, USA
| | - Tivadar Orban
- Department of Pharmacology, Case Western Reserve University, School of Medicine, Cleveland, OH 44106, USA
| | - Mengyuan Xu
- Department of Pharmacology, Case Western Reserve University, School of Medicine, Cleveland, OH 44106, USA
| | - Wilnelly Hernandez-Sanchez
- Department of Pharmacology, Case Western Reserve University, School of Medicine, Cleveland, OH 44106, USA
| | - Maria de la Fuente
- Department of Pharmacology, Case Western Reserve University, School of Medicine, Cleveland, OH 44106, USA
| | - Krzysztof Palczewski
- Department of Pharmacology, Case Western Reserve University, School of Medicine, Cleveland, OH 44106, USA
| | - Derek J Taylor
- Department of Pharmacology, Case Western Reserve University, School of Medicine, Cleveland, OH 44106, USA .,Department of Biochemistry, Case Western Reserve University, School of Medicine, Cleveland, OH 44106, USA
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31
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Lee JR, Xie X, Yang K, Zhang J, Lee SY, Shippen DE. Dynamic Interactions of Arabidopsis TEN1: Stabilizing Telomeres in Response to Heat Stress. THE PLANT CELL 2016; 28:2212-2224. [PMID: 27609839 PMCID: PMC5059806 DOI: 10.1105/tpc.16.00408] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Revised: 08/25/2016] [Accepted: 09/06/2016] [Indexed: 05/15/2023]
Abstract
Telomeres are the essential nucleoprotein structures that provide a physical cap for the ends of linear chromosomes. The highly conserved CST (CTC1/STN1/TEN1) protein complex facilitates telomeric DNA replication and promotes telomere stability. Here we report three unexpected properties of Arabidopsis thaliana TEN1 that indicate it possesses functions distinct from other previously characterized telomere proteins. First, we show that telomeres in ten1 mutants are highly sensitive to thermal stress. Heat shock causes abrupt and dramatic loss of telomeric DNA in ten1 plants, likely via deletional recombination. Second, we show that AtTEN1 has the properties of a heat-shock induced molecular chaperone. At elevated temperature, AtTEN1 rapidly assembles into high molecular weight homo-oligomeric complexes that efficiently suppress heat-induced aggregation of model protein substrates in vitro. Finally, we report that AtTEN1 specifically protects CTC1 from heat-induced aggregation in vitro, and from heat-induced protein degradation and loss of telomere association in vivo. Collectively, these observations define Arabidopsis TEN1 as a highly dynamic protein that works in concert with CTC1 to preserve telomere integrity in response to environmental stress.
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Affiliation(s)
- Jung Ro Lee
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843-2128
| | - Xiaoyuan Xie
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843-2128
| | - Kailu Yang
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843-2128
| | - Junjie Zhang
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843-2128
| | - Sang Yeol Lee
- Division of Applied Life Sciences (BK21) and PMBBRC, Gyeongsang National University, Jinju 52828, Republic of Korea
| | - Dorothy E Shippen
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843-2128
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32
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Hirai Y, Tamura M, Otani J, Ishikawa F. NEK6-mediated phosphorylation of human TPP1 regulates telomere length through telomerase recruitment. Genes Cells 2016; 21:874-89. [DOI: 10.1111/gtc.12391] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2016] [Accepted: 05/31/2016] [Indexed: 12/29/2022]
Affiliation(s)
- Yugo Hirai
- Department of Gene Mechanisms; Graduate School of Biostudies; Kyoto University; Yoshida-Konoe-cho Sakyo-ku Kyoto 606-8501 Japan
| | - Miki Tamura
- Department of Gene Mechanisms; Graduate School of Biostudies; Kyoto University; Yoshida-Konoe-cho Sakyo-ku Kyoto 606-8501 Japan
| | - Junji Otani
- Department of Gene Mechanisms; Graduate School of Biostudies; Kyoto University; Yoshida-Konoe-cho Sakyo-ku Kyoto 606-8501 Japan
| | - Fuyuki Ishikawa
- Department of Gene Mechanisms; Graduate School of Biostudies; Kyoto University; Yoshida-Konoe-cho Sakyo-ku Kyoto 606-8501 Japan
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33
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Telomere Length Maintenance and Cardio-Metabolic Disease Prevention Through Exercise Training. Sports Med 2016; 46:1213-37. [DOI: 10.1007/s40279-016-0482-4] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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34
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Meng T, Tang SF, Qin QP, Liang YL, Wu CX, Wang CY, Yan HT, Dong JX, Liu YC. Evaluation of the effect of iodine substitution of 8-hydroxyquinoline on its platinum(ii) complex: cytotoxicity, cell apoptosis and telomerase inhibition. MEDCHEMCOMM 2016. [DOI: 10.1039/c6md00201c] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A new Pt(ii) complex of 5,7-diiodo-8-quinolinol was synthesized and studied on its more effective antitumor mechanism than that of 8-quinolinol.
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Affiliation(s)
- Ting Meng
- State Key Laboratory for the Chemistry and Molecular Engineering of Medicinal Resources
- School of Chemistry and Pharmaceutical Sciences
- Guangxi Normal University
- Guilin 541004
- PR China
| | - Shang-Feng Tang
- State Key Laboratory for the Chemistry and Molecular Engineering of Medicinal Resources
- School of Chemistry and Pharmaceutical Sciences
- Guangxi Normal University
- Guilin 541004
- PR China
| | - Qi-Pin Qin
- State Key Laboratory for the Chemistry and Molecular Engineering of Medicinal Resources
- School of Chemistry and Pharmaceutical Sciences
- Guangxi Normal University
- Guilin 541004
- PR China
| | - Yue-Lan Liang
- State Key Laboratory for the Chemistry and Molecular Engineering of Medicinal Resources
- School of Chemistry and Pharmaceutical Sciences
- Guangxi Normal University
- Guilin 541004
- PR China
| | - Chen-Xuan Wu
- State Key Laboratory for the Chemistry and Molecular Engineering of Medicinal Resources
- School of Chemistry and Pharmaceutical Sciences
- Guangxi Normal University
- Guilin 541004
- PR China
| | - Chen-Yu Wang
- State Key Laboratory for the Chemistry and Molecular Engineering of Medicinal Resources
- School of Chemistry and Pharmaceutical Sciences
- Guangxi Normal University
- Guilin 541004
- PR China
| | - Hou-Tian Yan
- State Key Laboratory for the Chemistry and Molecular Engineering of Medicinal Resources
- School of Chemistry and Pharmaceutical Sciences
- Guangxi Normal University
- Guilin 541004
- PR China
| | - Jia-Xin Dong
- State Key Laboratory for the Chemistry and Molecular Engineering of Medicinal Resources
- School of Chemistry and Pharmaceutical Sciences
- Guangxi Normal University
- Guilin 541004
- PR China
| | - Yan-Cheng Liu
- State Key Laboratory for the Chemistry and Molecular Engineering of Medicinal Resources
- School of Chemistry and Pharmaceutical Sciences
- Guangxi Normal University
- Guilin 541004
- PR China
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35
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Zhang Y, Wu Y, Mao P, Li F, Han X, Zhang Y, Jiang S, Chen Y, Huang J, Liu D, Zhao Y, Ma W, Songyang Z. Cold-inducible RNA-binding protein CIRP/hnRNP A18 regulates telomerase activity in a temperature-dependent manner. Nucleic Acids Res 2015; 44:761-75. [PMID: 26673712 PMCID: PMC4737163 DOI: 10.1093/nar/gkv1465] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2015] [Accepted: 12/01/2015] [Indexed: 01/22/2023] Open
Abstract
The telomerase is responsible for adding telomeric repeats to chromosomal ends and consists of the reverse transcriptase TERT and the RNA subunit TERC. The expression and activity of the telomerase are tightly regulated, and aberrant activation of the telomerase has been observed in >85% of human cancers. To better understand telomerase regulation, we performed immunoprecipitations coupled with mass spectrometry (IP-MS) and identified cold inducible RNA-binding protein (CIRP or hnRNP A18) as a telomerase-interacting factor. We have found that CIRP is necessary to maintain telomerase activities at both 32°C and 37°C. Furthermore, inhibition of CIRP by CRISPR-Cas9 or siRNA knockdown led to reduced telomerase activities and shortened telomere length, suggesting an important role of CIRP in telomere maintenance. We also provide evidence here that CIRP associates with the active telomerase complex through direct binding of TERC and regulates Cajal body localization of the telomerase. In addition, CIRP regulates the level of TERT mRNAs. At the lower temperature, TERT mRNA is upregulated in a CIRP-dependent manner to compensate for reduced telomerase activities. Taken together, these findings highlight the dual roles that CIRP plays in regulating TERT and TERC, and reveal a new class of telomerase modulators in response to hypothermia conditions.
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Affiliation(s)
- Youwei Zhang
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China Collaborative Innovation Center for Cancer Medicine, Institute of Healthy Aging Research, Sun Yat-sen University, Guangzhou 510006, China
| | - Yangxiu Wu
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Pingsu Mao
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Feng Li
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Xin Han
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Yi Zhang
- Verna and Marrs Mclean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
| | - Shuai Jiang
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Yuxi Chen
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Junjiu Huang
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Dan Liu
- Verna and Marrs Mclean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
| | - Yong Zhao
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Wenbin Ma
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China Collaborative Innovation Center for Cancer Medicine, Institute of Healthy Aging Research, Sun Yat-sen University, Guangzhou 510006, China
| | - Zhou Songyang
- Key Laboratory of Gene Engineering of the Ministry of Education, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China Collaborative Innovation Center for Cancer Medicine, Institute of Healthy Aging Research, Sun Yat-sen University, Guangzhou 510006, China Verna and Marrs Mclean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
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Abstract
In this review, Schmidt and Cech cover human telomerase biogenesis, trafficking, and activation, comparing key aspects with the analogous events in other species. Telomerase is the ribonucleoprotein enzyme that catalyzes the extension of telomeric DNA in eukaryotes. Recent work has begun to reveal key aspects of the assembly of the human telomerase complex, its intracellular trafficking involving Cajal bodies, and its recruitment to telomeres. Once telomerase has been recruited to the telomere, it appears to undergo a separate activation step, which may include an increase in its repeat addition processivity. This review covers human telomerase biogenesis, trafficking, and activation, comparing key aspects with the analogous events in other species.
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Affiliation(s)
- Jens C Schmidt
- Howard Hughes Medical Institute, Department of Chemistry and Biochemistry, BioFrontiers Institute, University of Colorado Boulder, Boulder, Colorado 80309, USA
| | - Thomas R Cech
- Howard Hughes Medical Institute, Department of Chemistry and Biochemistry, BioFrontiers Institute, University of Colorado Boulder, Boulder, Colorado 80309, USA
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Bellon M, Nicot C. Multiple Pathways Control the Reactivation of Telomerase in HTLV-I-Associated Leukemia. ACTA ACUST UNITED AC 2015; 2. [PMID: 26430700 DOI: 10.15436/2377-0902.15.017] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
While telomerase (hTERT) activity is absent from normal somatic cells, reactivation of hTERT expression is a hallmark of cancer cells. Telomerase activity is required for avoiding replicative senescence and supports immortalization of cellular proliferation. Only a minority of cancer cells rely on a telomerase-independent process known as alternative lengthening of telomeres, ALT, to sustain cancer cell proliferation. Multiple genetic, epigenetic, and viral mechanisms have been found to de-regulate telomerase gene expression, thereby increasing the risk of cellular transformation. Here, we review the different strategies used by the Human T-cell leukemia virus type 1, HTLV-I, to activate hTERT expression and stimulate its enzymatic activity in virally infected CD4 T cells. The implications of hTERT reactivation in HTLV-I pathogenesis and disease treatment are discussed.
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Affiliation(s)
- Marcia Bellon
- Department of Pathology and Laboratory Medicine, Center for Viral Oncology, University of Kansas Medical Center, 3901 Rainbow Boulevard, Kansas City, KS 66160, USA
| | - Christophe Nicot
- Department of Pathology and Laboratory Medicine, Center for Viral Oncology, University of Kansas Medical Center, 3901 Rainbow Boulevard, Kansas City, KS 66160, USA
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38
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Abstract
The mini-review stemmed from a recent meeting on national aging research strategies in China discusses the components and challenges of aging research in China. Highlighted are the major efforts of a number of research teams, funding situations and outstanding examples of recent major research achievements. Finally, authors discuss potential targets and strategies of aging research in China.
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39
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Renfrew KB, Song X, Lee JR, Arora A, Shippen DE. POT1a and components of CST engage telomerase and regulate its activity in Arabidopsis. PLoS Genet 2014; 10:e1004738. [PMID: 25329641 PMCID: PMC4199523 DOI: 10.1371/journal.pgen.1004738] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2014] [Accepted: 09/06/2014] [Indexed: 11/18/2022] Open
Abstract
Protection of Telomeres 1 (POT1) is a conserved nucleic acid binding protein implicated in both telomere replication and chromosome end protection. We previously showed that Arabidopsis thaliana POT1a associates with the TER1 telomerase RNP, and is required for telomere length maintenance in vivo. Here we further dissect the function of POT1a and explore its interplay with the CST (CTC1/STN1/TEN1) telomere complex. Analysis of pot1a null mutants revealed that POT1a is not required for telomerase recruitment to telomeres, but is required for telomerase to maintain telomere tracts. We show that POT1a stimulates the synthesis of long telomere repeat arrays by telomerase, likely by enhancing repeat addition processivity. We demonstrate that POT1a binds STN1 and CTC1 in vitro, and further STN1 and CTC1, like POT1a, associate with enzymatically active telomerase in vivo. Unexpectedly, the in vitro interaction of STN1 with TEN1 and POT1a was mutually exclusive, indicating that POT1a and TEN1 may compete for the same binding site on STN1 in vivo. Finally, unlike CTC1 and STN1, TEN1 was not associated with active telomerase in vivo, consistent with our previous data showing that TEN1 negatively regulates telomerase enzyme activity. Altogether, our data support a two-state model in which POT1a promotes an extendable telomere state via contacts with the telomerase RNP as well as STN1 and CTC1, while TEN1 opposes these functions.
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Affiliation(s)
- Kyle B. Renfrew
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, United States of America
| | - Xiangyu Song
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, United States of America
| | - Jung Ro Lee
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, United States of America
| | - Amit Arora
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, United States of America
| | - Dorothy E. Shippen
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, United States of America
- * E-mail:
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40
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Sexton AN, Regalado SG, Lai CS, Cost GJ, O'Neil CM, Urnov FD, Gregory PD, Jaenisch R, Collins K, Hockemeyer D. Genetic and molecular identification of three human TPP1 functions in telomerase action: recruitment, activation, and homeostasis set point regulation. Genes Dev 2014; 28:1885-99. [PMID: 25128433 PMCID: PMC4197946 DOI: 10.1101/gad.246819.114] [Citation(s) in RCA: 86] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2014] [Accepted: 07/28/2014] [Indexed: 01/29/2023]
Abstract
Telomere length homeostasis is essential for the long-term survival of stem cells, and its set point determines the proliferative capacity of differentiated cell lineages by restricting the reservoir of telomeric repeats. Knockdown and overexpression studies in human tumor cells showed that the shelterin subunit TPP1 recruits telomerase to telomeres through a region termed the TEL patch. However, these studies do not resolve whether the TPP1 TEL patch is the only mechanism for telomerase recruitment and whether telomerase regulation studied in tumor cells is representative of nontransformed cells such as stem cells. Using genome engineering of human embryonic stem cells, which have physiological telomere length homeostasis, we establish that the TPP1 TEL patch is genetically essential for telomere elongation and thus long-term cell viability. Furthermore, genetic bypass, protein fusion, and intragenic complementation assays define two distinct additional mechanisms of TPP1 involvement in telomerase action at telomeres. We demonstrate that TPP1 provides an essential step of telomerase activation as well as feedback regulation of telomerase by telomere length, which is necessary to determine the appropriate telomere length set point in human embryonic stem cells. These studies reveal and resolve multiple TPP1 roles in telomere elongation and stem cell telomere length homeostasis.
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Affiliation(s)
- Alec N Sexton
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, California 94720, USA
| | - Samuel G Regalado
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, California 94720, USA
| | - Christine S Lai
- The Whitehead Institute for Biomedical Research, Cambridge, Massachusetts 02142, USA
| | - Gregory J Cost
- Sangamo BioSciences, Inc., Richmond, California 94804, USA
| | | | - Fyodor D Urnov
- Sangamo BioSciences, Inc., Richmond, California 94804, USA
| | | | - Rudolf Jaenisch
- The Whitehead Institute for Biomedical Research, Cambridge, Massachusetts 02142, USA
| | - Kathleen Collins
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, California 94720, USA;
| | - Dirk Hockemeyer
- Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, California 94720, USA;
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41
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Zemp I, Lingner J. The shelterin component TPP1 is a binding partner and substrate for the deubiquitinating enzyme USP7. J Biol Chem 2014; 289:28595-606. [PMID: 25172512 PMCID: PMC4192509 DOI: 10.1074/jbc.m114.596056] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
The telomeric shelterin component TPP1 has critical functions in telomeric protein complex assembly and telomerase recruitment and regulation. Here we identify USP7 as a novel interacting protein of the oligonucleotide/oligosaccharide-binding fold of TPP1, which was previously known to recruit telomerase to telomeres. We identify amino acids in TPP1 and USP7 that are critical for their interaction and multiple lysines within TPP1 that are oligo-ubiquitinated and deubiquitinated by USP7. Mutational analysis indicated that human TPP1 does not require ubiquitination for telomere association in contrast to previous observations reported for mouse Tpp1. Ubiquitination of human TPP1 also had no detectable effects on known protein interactions of TPP1 with TIN2, POT1, the CTC1-STN1-TEN1 complex, and telomerase. However, the close proximity of USP7 and telomerase binding sites on TPP1 suggest possible cross-talks. In addition, we found that TPP1 is degraded in a proteasome-dependent manner. Prevention of TPP1 ubiquitination prolonged TPP1 half-life ∼2-fold from 45 to 90 min, and remarkably, proteasome inhibition prompted complete stability of TPP1. This indicates that the proteasome destabilizes TPP1 through both direct and indirect pathways possibly involving TPP1-interacting proteins. Altogether, our work identifies novel regulatory circuits that contribute to TPP1 stability and function.
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Affiliation(s)
- Ivo Zemp
- From the Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences (SV), Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Joachim Lingner
- From the Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences (SV), Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
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42
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Martínez P, Ferrara‐Romeo I, Flores JM, Blasco MA. Essential role for the TRF2 telomere protein in adult skin homeostasis. Aging Cell 2014; 13:656-68. [PMID: 24725274 PMCID: PMC4326939 DOI: 10.1111/acel.12221] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/23/2014] [Indexed: 11/29/2022] Open
Abstract
TRF2 is a component of shelterin, the protein complex that protects the ends of mammalian chromosomes. TRF2 is essential for telomere capping owing to its roles in suppressing an ATM-dependent DNA damage response (DDR) at chromosome ends and inhibiting end-to-end chromosome fusions. Mice deficient for TRF2 are early embryonic lethal. However, the role of TRF2 in later stages of development and in the adult organism remains largely unaddressed, with the exception of liver, where TRF2 was found to be dispensable for maintaining tissue function. Here, we study the impact of TRF2 conditional deletion in stratified epithelia by generating the TRF2∆/∆-K5-Cre mouse model, which targets TRF2 deletion to the skin from embryonic day E11.5. In marked contrast to TRF2 deletion in the liver, TRF2∆/∆-K5-Cre mice show lethality in utero reaching 100% lethality perinataly. At the molecular and cellular level, TRF2 deletion provokes induction of an acute DDR at telomeres, leading to activation of p53 signaling pathways and to programed cell death since the time of Cre expression at E11.5. Unexpectedly, neither inhibition of the NHEJ pathway by abrogation of 53BP1 nor inhibition of DDR by p53 deficiency rescued these severe phenotypes. Instead, TRF2 deletion provokes an extensive epidermal cell death accompanied by severe inflammation already at E16.5 embryos, which are independent of p53. These results are in contrast with conditional deletion of TRF1 and TPP1 in the skin, where p53 deficiency rescued the associated skin phenotypes, highlighting the comparatively more essential role of TRF2 in skin homeostasis.
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Affiliation(s)
- Paula Martínez
- Telomeres and Telomerase Group Molecular Oncology Program Spanish National Cancer Centre (CNIO) Melchor Fernández Almagro 3E‐28029 Madrid Spain
| | - Iole Ferrara‐Romeo
- Telomeres and Telomerase Group Molecular Oncology Program Spanish National Cancer Centre (CNIO) Melchor Fernández Almagro 3E‐28029 Madrid Spain
| | - Juana M. Flores
- Animal Surgery and Medicine Department Facultad de Veterinaria Complutense University of Madrid 28029Madrid Spain
| | - Maria A. Blasco
- Telomeres and Telomerase Group Molecular Oncology Program Spanish National Cancer Centre (CNIO) Melchor Fernández Almagro 3E‐28029 Madrid Spain
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43
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Dickey TH, Wuttke DS. The telomeric protein Pot1 from Schizosaccharomyces pombe binds ssDNA in two modes with differing 3' end availability. Nucleic Acids Res 2014; 42:9656-65. [PMID: 25074378 PMCID: PMC4150783 DOI: 10.1093/nar/gku680] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Telomere protection and length regulation are important processes for aging, cancer and several other diseases. At the heart of these processes lies the single-stranded DNA (ssDNA)-binding protein Pot1, a component of the telomere maintenance complex shelterin, which is present in species ranging from fission yeast to humans. Pot1 contains a dual OB-fold DNA-binding domain (DBD) that fully confers its high affinity for telomeric ssDNA. Studies of S. pombe Pot1-DBD and its individual OB-fold domains revealed a complex non-additive behavior of the two OB-folds in the context of the complete Pot1 protein. This behavior includes the use of multiple distinct binding modes and an ability to form higher order complexes. Here we use NMR and biochemical techniques to investigate the structural features of the complete Pot1-DBD. These experiments reveal one binding mode characterized by only subtle alternations to the individual OB-fold subdomain structures, resulting in an inaccessible 3′ end of the ssDNA. The second binding mode, which has equivalent affinity, interacts differently with the 3′ end, rendering it available for interaction with other proteins. These findings suggest a structural switch that contributes to telomere end-protection and length regulation.
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Affiliation(s)
- Thayne H Dickey
- Department of Chemistry and Biochemistry, 596 UCB, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Deborah S Wuttke
- Department of Chemistry and Biochemistry, 596 UCB, University of Colorado Boulder, Boulder, CO 80309, USA
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44
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Hwang H, Kreig A, Calvert J, Lormand J, Kwon Y, Daley JM, Sung P, Opresko PL, Myong S. Telomeric overhang length determines structural dynamics and accessibility to telomerase and ALT-associated proteins. Structure 2014; 22:842-53. [PMID: 24836024 DOI: 10.1016/j.str.2014.03.013] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2013] [Revised: 02/07/2014] [Accepted: 03/04/2014] [Indexed: 02/03/2023]
Abstract
The G-rich single-stranded DNA at the 3' end of human telomeres can self-fold into G-quaduplex (GQ). However, telomere lengthening by telomerase or the recombination-based alternative lengthening of telomere (ALT) mechanism requires protein loading on the overhang. Using single-molecule fluorescence spectroscopy, we discovered that lengthening the telomeric overhang also increased the rate of dynamic exchanges between structural conformations. Overhangs with five to seven TTAGGG repeats, compared with four repeats, showed much greater dynamics and accessibility to telomerase binding and activity and loading of the ALT-associated proteins RAD51, WRN, and BLM. Although the eight repeats are highly dynamic, they can fold into two GQs, which limited protein accessibility. In contrast, the telomere-specific protein POT1 is unique in that it binds independently of repeat number. Our results suggest that the telomeric overhang length and dynamics may contribute to the regulation of telomere extension via telomerase action and the ALT mechanism.
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Affiliation(s)
- Helen Hwang
- Bioengineering Department, University of Illinois, 1304 West Springfield Avenue, Urbana, IL 61801, USA; Medical Scholars Program, University of Illinois, 506 South Matthews Avenue, Urbana, IL 61801, USA
| | - Alex Kreig
- Bioengineering Department, University of Illinois, 1304 West Springfield Avenue, Urbana, IL 61801, USA
| | - Jacob Calvert
- Bioengineering Department, University of Illinois, 1304 West Springfield Avenue, Urbana, IL 61801, USA
| | - Justin Lormand
- Department of Environmental and Occupational Health, University of Pittsburgh, 100 Technology Drive, Suite 326, BRIDG, Pittsburgh, PA 15219, USA
| | - Yongho Kwon
- Department of Molecular Biophysics and Biochemistry, Yale University, 333 Cedar Street, P.O. Box 208024, New Haven, CT 06520, USA
| | - James M Daley
- Department of Molecular Biophysics and Biochemistry, Yale University, 333 Cedar Street, P.O. Box 208024, New Haven, CT 06520, USA
| | - Patrick Sung
- Department of Molecular Biophysics and Biochemistry, Yale University, 333 Cedar Street, P.O. Box 208024, New Haven, CT 06520, USA
| | - Patricia L Opresko
- Department of Environmental and Occupational Health, University of Pittsburgh, 100 Technology Drive, Suite 326, BRIDG, Pittsburgh, PA 15219, USA
| | - Sua Myong
- Bioengineering Department, University of Illinois, 1304 West Springfield Avenue, Urbana, IL 61801, USA; Institute for Genomic Biology, University of Illinois, 1206 West Gregory Street, Urbana, IL 61801, USA; Physics Frontier Center (Center of Physics for Living Cells), University of Illinois, 1110 West Green Street, Urbana, IL 61801, USA.
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45
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Rajavel M, Mullins MR, Taylor DJ. Multiple facets of TPP1 in telomere maintenance. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2014; 1844:1550-9. [PMID: 24780581 DOI: 10.1016/j.bbapap.2014.04.014] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2014] [Revised: 04/01/2014] [Accepted: 04/18/2014] [Indexed: 11/30/2022]
Abstract
Telomeres are nucleoprotein complexes that cap the ends of all linear chromosomes and function to prevent aberrant repair and end-to-end chromosome fusions. In somatic cells, telomere shortening is a natural part of the aging process as it occurs with each round of cell division. In germ and stem cells, however, the enzyme telomerase synthesizes telomere DNA to counter-balance telomere shortening and help maintain cellular proliferation. Of the primary telomere end-binding proteins, TPP1 has recently emerged as a primary contributor in protecting telomere DNA and in recruiting telomerase to the telomere ends. In this review, we summarize the current knowledge regarding the role of TPP1 in telomere maintenance.
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Affiliation(s)
- Malligarjunan Rajavel
- Department of Pharmacology, Case Western Reserve University, School of Medicine, Cleveland OH 44106, USA
| | - Michael R Mullins
- Department of Pharmacology, Case Western Reserve University, School of Medicine, Cleveland OH 44106, USA
| | - Derek J Taylor
- Department of Pharmacology, Case Western Reserve University, School of Medicine, Cleveland OH 44106, USA; Department of Biochemistry, Case Western Reserve University, School of Medicine, Cleveland OH 44106, USA.
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46
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Shim G, Ricoul M, Hempel WM, Azzam EI, Sabatier L. Crosstalk between telomere maintenance and radiation effects: A key player in the process of radiation-induced carcinogenesis. MUTATION RESEARCH. REVIEWS IN MUTATION RESEARCH 2014; 760:S1383-5742(14)00002-7. [PMID: 24486376 PMCID: PMC4119099 DOI: 10.1016/j.mrrev.2014.01.001] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2013] [Revised: 01/14/2014] [Accepted: 01/22/2014] [Indexed: 02/06/2023]
Abstract
It is well established that ionizing radiation induces chromosomal damage, both following direct radiation exposure and via non-targeted (bystander) effects, activating DNA damage repair pathways, of which the proteins are closely linked to telomeric proteins and telomere maintenance. Long-term propagation of this radiation-induced chromosomal damage during cell proliferation results in chromosomal instability. Many studies have shown the link between radiation exposure and radiation-induced changes in oxidative stress and DNA damage repair in both targeted and non-targeted cells. However, the effect of these factors on telomeres, long established as guardians of the genome, still remains to be clarified. In this review, we will focus on what is known about how telomeres are affected by exposure to low- and high-LET ionizing radiation and during proliferation, and will discuss how telomeres may be a key player in the process of radiation-induced carcinogenesis.
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47
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Li Z, Yang X, Xia N, Yang L, Yu H, Zhou F, X C, Zhou Y. PTOP and TRF1 help enhance the radio resistance in breast cancer cell. Cancer Cell Int 2014; 14:7. [PMID: 24460895 PMCID: PMC3984749 DOI: 10.1186/1475-2867-14-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2013] [Accepted: 01/22/2014] [Indexed: 12/19/2022] Open
Abstract
Purpose The telomere binding proteins play an important role in telomere function, which contribute greatly to the radio resistant in human cancers. This research is designed to investigate the relationship among the telomere length, telomerase activity and changes of telomere binding protein PTOP and TRF1 in radio resistant breast cancer cell lines. Methods Irradiate MDA-MB-435 s breast cancer cell with total dose of 60 Gy delivered in 2 Gy/fraction and 6 Gy/fraction respectively, then measuring their telomere length by Southern blot analysis,telomerase activity by Telomerase PCR Elisa and detecting the expression of PTOP and TRF1 in both gene and protein levels. To further investigate the function of PTOP, using lentivirus technic to silence the PTOP gene and the detected the new silenced cells by southern blot and telomerase activity. Results 2 radio resistant breast cancer cell lines were successfully established. The MDA-MB-435 s R60/6 was (approximate 8.1-8.6 kbp) about 2–2.4 folds to the patent cell (3.6-4.2 kbp), the MDA-MB-435 s R60/2 cell (approximate 5.3-6.3 kbp) was about 1.3-1.75 fold to the parent cell line. The telomerase activity was more enhanced in radio resistant cell lines than the parent cell. The expression of PTOP and TRF1 were significant increased in radio resistant cell lines than the patent cell in both gene and protein level. Otherwise, after using lentivirus technic to silence the PTOP gene, we found the radio resistant cell lines were significant decrease their radio resistances and telomerase activities. Conclusion The telomere binding protein PTOP and TRF1 were increased expressed in radio resistant breast cancer cell, PTOP was observed instinct positive correlated with telomere lengthen and telomerase activity enhancement.
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Affiliation(s)
| | | | | | | | | | | | | | - Yunfeng Zhou
- Department of Radiation and Medical Oncology, Zhongnan Hospital, Wuhan University, Donghu road 168, 430071, Wuhan City, Hubei Province, China.
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48
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Han X, Liu D, Zhang Y, Li Y, Lu W, Chen J, Songyang Z. Akt regulates TPP1 homodimerization and telomere protection. Aging Cell 2013; 12:1091-9. [PMID: 23862686 DOI: 10.1111/acel.12137] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/10/2013] [Indexed: 12/01/2022] Open
Abstract
Telomeres are specialized structures at the ends of eukaryotic chromosomes that are important for maintaining genome stability and integrity. Telomere dysfunction has been linked to aging and cancer development. In mammalian cells, extensive studies have been carried out to illustrate how core telomeric proteins assemble on telomeres to recruit the telomerase and additional factors for telomere maintenance and protection. In comparison, how changes in growth signaling pathways impact telomeres and telomere-binding proteins remains largely unexplored. The phosphatidylinositol 3-kinase (PI3-K)/Akt (also known as PKB) pathway, one of the best characterized growth signaling cascades, regulates a variety of cellular function including cell proliferation, survival, metabolism, and DNA repair, and dysregulation of PI3-K/Akt signaling has been linked to aging and diseases such as cancer and diabetes. In this study, we provide evidence that the Akt signaling pathway plays an important role in telomere protection. Akt inhibition either by chemical inhibitors or small interfering RNAs induced telomere dysfunction. Furthermore, we found that TPP1 could homodimerize through its OB-fold, a process that was dependent on the Akt kinase. Telomere damage and reduced TPP1 dimerization as a result of Akt inhibition was also accompanied by diminished recruitment of TPP1 and POT1 to the telomeres. Our findings highlight a previously unknown link between Akt signaling and telomere protection.
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Affiliation(s)
- Xin Han
- Key Laboratory of Gene Engineering of the Ministry of Education; School of Life Sciences and Key Laboratory of Reproductive Medicine of Guangdong Province; the First Affiliated Hospital; Sun Yat-Sen University; Guangzhou Guangzhou China
| | - Dan Liu
- Verna and Marrs Mclean Department of Biochemistry and Molecular Biology; Baylor College of Medicine; One Baylor Plaza; Houston TX 77030 USA
| | - Yi Zhang
- Verna and Marrs Mclean Department of Biochemistry and Molecular Biology; Baylor College of Medicine; One Baylor Plaza; Houston TX 77030 USA
| | - Yujing Li
- Key Laboratory of Gene Engineering of the Ministry of Education; School of Life Sciences and Key Laboratory of Reproductive Medicine of Guangdong Province; the First Affiliated Hospital; Sun Yat-Sen University; Guangzhou Guangzhou China
| | - Weisi Lu
- Key Laboratory of Gene Engineering of the Ministry of Education; School of Life Sciences and Key Laboratory of Reproductive Medicine of Guangdong Province; the First Affiliated Hospital; Sun Yat-Sen University; Guangzhou Guangzhou China
| | - Junjie Chen
- Department of Experimental Radiation Oncology; The University of Texas M D Anderson Cancer Center; Houston TX 77030 USA
| | - Zhou Songyang
- Key Laboratory of Gene Engineering of the Ministry of Education; School of Life Sciences and Key Laboratory of Reproductive Medicine of Guangdong Province; the First Affiliated Hospital; Sun Yat-Sen University; Guangzhou Guangzhou China
- Verna and Marrs Mclean Department of Biochemistry and Molecular Biology; Baylor College of Medicine; One Baylor Plaza; Houston TX 77030 USA
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49
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Fadri-Moskwik M, Zhou Q, Chai W. Beyond Telomerase: Telomere Instability as a Novel Target for Cancer Therapy. J Mol Genet Med 2013; 7. [PMID: 27123041 PMCID: PMC4844356 DOI: 10.4172/1747-0862.1000091] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Telomeres are areas of heterochromatin composed of TTAGGG repeats located at the ends of linear chromosomes. They play a critical role in keeping genome stable and preventing premature aging diseases and the development of cancer. Characterizing mechanisms of telomere maintenance and understanding how their deregulation contributes to human diseases are therefore important for developing novel therapies. A key mechanism driving telomere maintenance and replicative immortality in cancer cells is telomere elongation by telomerase, and many emerging potential telomere-based therapies have focused on targeting telomerase components. By contrast, recent studies on telomere maintenance mechanism suggest that disrupting telomere stability by interfering with alternative mechanisms of telomere synthesis or protection may also yield new strategies for the treatment of cancer. This review will focus on emerging regulators of telomere synthesis or maintenance, such as G4 telomeric DNA, the CST complex, the t-loop, and shelterins, and discuss their potential as targets for anti-cancer chemotherapeutic intervention in the future.
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Affiliation(s)
- Maria Fadri-Moskwik
- Section of Medical Sciences and School of Molecular Biosciences, Washington State University, USA
| | - Qing Zhou
- Section of Medical Sciences and School of Molecular Biosciences, Washington State University, USA
| | - Weihang Chai
- Section of Medical Sciences and School of Molecular Biosciences, Washington State University, USA
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50
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Yang L, Wang W, Hu L, Yang X, Zhong J, Li Z, Yang H, Lei H, Yu H, Liao Z, Zhou F, Xie C, Zhou Y. Telomere-binding protein TPP1 modulates telomere homeostasis and confers radioresistance to human colorectal cancer cells. PLoS One 2013; 8:e81034. [PMID: 24260532 PMCID: PMC3834294 DOI: 10.1371/journal.pone.0081034] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2013] [Accepted: 10/08/2013] [Indexed: 02/01/2023] Open
Abstract
BACKGROUND Radiotherapy is one of the major therapeutic strategies in cancer treatment. The telomere-binding protein TPP1 is an important component of the shelterin complex at mammalian telomeres. Our previous reports showed that TPP1 expression was elevated in radioresistant cells, but the exact effects and mechanisms of TPP1 on radiosensitivity is unclear. PRINCIPAL FINDINGS In this study, we found that elevated TPP1 expression significantly correlated with radioresistance and longer telomere length in human colorectal cancer cell lines. Moreover, TPP1 overexpression showed lengthened telomere length and a significant decrease of radiosensitivity to X-rays. TPP1 mediated radioresistance was correlated with a decreased apoptosis rate after IR exposure. Furthermore, TPP1 overexpression showed prolonged G2/M arrest mediated by ATM/ATR-Chk1 signal pathway after IR exposure. Moreover, TPP1 overexpression accelerated the repair kinetics of total DNA damage and telomere dysfunction induced by ionizing radiation. CONCLUSIONS We demonstrated that elevated expressions of TPP1 in human colorectal cancer cells could protect telomere from DNA damage and confer radioresistance. These results suggested that TPP1 may be a potential target in the radiotherapy of colorectal cancer.
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Affiliation(s)
- Lei Yang
- Hubei Cancer Clinical Study Center, Hubei Key Laboratory of Tumor Biological Behaviors, Zhongnan Hospital, Wuhan University, Wuhan, China
| | - Wenbo Wang
- Hubei Cancer Clinical Study Center, Hubei Key Laboratory of Tumor Biological Behaviors, Zhongnan Hospital, Wuhan University, Wuhan, China
| | - Liu Hu
- Hubei Cancer Clinical Study Center, Hubei Key Laboratory of Tumor Biological Behaviors, Zhongnan Hospital, Wuhan University, Wuhan, China
| | - Xiaoxi Yang
- Hubei Cancer Clinical Study Center, Hubei Key Laboratory of Tumor Biological Behaviors, Zhongnan Hospital, Wuhan University, Wuhan, China
| | - Juan Zhong
- Department of Oncology, the Fifth Hospital of Wuhan, Wuhan, China
| | - Zheng Li
- Hubei Cancer Clinical Study Center, Hubei Key Laboratory of Tumor Biological Behaviors, Zhongnan Hospital, Wuhan University, Wuhan, China
| | - Hui Yang
- Hubei Cancer Clinical Study Center, Hubei Key Laboratory of Tumor Biological Behaviors, Zhongnan Hospital, Wuhan University, Wuhan, China
| | - Han Lei
- Hubei Cancer Clinical Study Center, Hubei Key Laboratory of Tumor Biological Behaviors, Zhongnan Hospital, Wuhan University, Wuhan, China
- Department of Radiation Oncology & Medical Oncology, Zhongnan Hospital, Wuhan University, Wuhan, China
| | - Haijun Yu
- Hubei Cancer Clinical Study Center, Hubei Key Laboratory of Tumor Biological Behaviors, Zhongnan Hospital, Wuhan University, Wuhan, China
- Department of Radiation Oncology & Medical Oncology, Zhongnan Hospital, Wuhan University, Wuhan, China
| | - ZhengKai Liao
- Hubei Cancer Clinical Study Center, Hubei Key Laboratory of Tumor Biological Behaviors, Zhongnan Hospital, Wuhan University, Wuhan, China
- Department of Radiation Oncology & Medical Oncology, Zhongnan Hospital, Wuhan University, Wuhan, China
| | - Fuxiang Zhou
- Hubei Cancer Clinical Study Center, Hubei Key Laboratory of Tumor Biological Behaviors, Zhongnan Hospital, Wuhan University, Wuhan, China
- Department of Radiation Oncology & Medical Oncology, Zhongnan Hospital, Wuhan University, Wuhan, China
| | - Conghua Xie
- Hubei Cancer Clinical Study Center, Hubei Key Laboratory of Tumor Biological Behaviors, Zhongnan Hospital, Wuhan University, Wuhan, China
- Department of Radiation Oncology & Medical Oncology, Zhongnan Hospital, Wuhan University, Wuhan, China
| | - Yunfeng Zhou
- Hubei Cancer Clinical Study Center, Hubei Key Laboratory of Tumor Biological Behaviors, Zhongnan Hospital, Wuhan University, Wuhan, China
- Department of Radiation Oncology & Medical Oncology, Zhongnan Hospital, Wuhan University, Wuhan, China
- * E-mail:
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