101
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Combining conservation and species-specific differences to determine how human telomerase binds telomeres. Proc Natl Acad Sci U S A 2019; 116:26505-26515. [PMID: 31822618 DOI: 10.1073/pnas.1911912116] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Telomerase catalyzes telomeric DNA synthesis at chromosome ends to allow for continued cell division. The telomeric protein TPP1 is essential for enhancing the processivity of telomerase and recruiting the enzyme to telomeres. The telomerase interaction surface on human TPP1 has been mapped to 2 regions of the N-terminal oligosaccharide/oligonucleotide-binding (OB) domain, namely the TPP1 glutamate (E) and leucine (L)-rich (TEL) patch and the N terminus of TPP1-oligosaccharide/oligonucleotide-binding (NOB) region. To map the telomerase side of the interface, we exploited the predicted structural similarities for human and Tetrahymena thermophila telomerase as well as the species specificity of human and mouse telomerase for their cognate TPP1 partners. We show that swapping in the telomerase essential N-terminal (TEN) and insertions in fingers domain (IFD)-TRAP regions of the human telomerase catalytic protein subunit TERT into the mouse TERT backbone is sufficient to bias the species specificity toward human TPP1. Employing a structural homology-based mutagenesis screen focused on surface residues of the TEN and IFD regions, we identified TERT residues that are critical for contacting TPP1 but dispensable for other aspects of telomerase structure or function. We present a functionally validated structural model for how human telomerase engages TPP1 at telomeres, setting the stage for a high-resolution structure of this interface.
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102
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Wang Y, Sušac L, Feigon J. Structural Biology of Telomerase. Cold Spring Harb Perspect Biol 2019; 11:cshperspect.a032383. [PMID: 31451513 DOI: 10.1101/cshperspect.a032383] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Telomerase is a DNA polymerase that extends the 3' ends of chromosomes by processively synthesizing multiple telomeric repeats. It is a unique ribonucleoprotein (RNP) containing a specialized telomerase reverse transcriptase (TERT) and telomerase RNA (TER) with its own template and other elements required with TERT for activity (catalytic core), as well as species-specific TER-binding proteins important for biogenesis and assembly (core RNP); other proteins bind telomerase transiently or constitutively to allow association of telomerase and other proteins with telomere ends for regulation of DNA synthesis. Here we describe how nuclear magnetic resonance (NMR) spectroscopy and X-ray crystallography of TER and protein domains helped define the structure and function of the core RNP, laying the groundwork for interpreting negative-stain and cryo electron microscopy (cryo-EM) density maps of Tetrahymena thermophila and human telomerase holoenzymes. As the resolution has improved from ∼30 Å to ∼5 Å, these studies have provided increasingly detailed information on telomerase architecture and mechanism.
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Affiliation(s)
- Yaqiang Wang
- Department of Chemistry and Biochemistry, University of California Los Angeles (UCLA), Los Angeles, California 90095-1569
| | - Lukas Sušac
- Department of Chemistry and Biochemistry, University of California Los Angeles (UCLA), Los Angeles, California 90095-1569
| | - Juli Feigon
- Department of Chemistry and Biochemistry, University of California Los Angeles (UCLA), Los Angeles, California 90095-1569
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103
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Li Y, Li X, Cao M, Jiang Y, Yan J, Liu Z, Yang R, Chen X, Sun P, Xiang R, Wang L, Shi Y. Seryl tRNA synthetase cooperates with POT1 to regulate telomere length and cellular senescence. Signal Transduct Target Ther 2019; 4:50. [PMID: 31815007 PMCID: PMC6882858 DOI: 10.1038/s41392-019-0078-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2019] [Revised: 04/04/2019] [Accepted: 04/23/2019] [Indexed: 12/13/2022] Open
Abstract
Deregulated telomere length is a causative factor in many physiological and pathological processes, including aging and cancer. Many studies focusing on telomeres have revealed important roles for cooperation between the Shelterin protein complex and telomerase in maintaining telomere length. However, it remains largely unknown whether and how aging-related stresses, such as deregulated protein homeostasis, impact telomere length. Here, we explored the possible roles of aminoacyl tRNA synthetases (AARSs), key enzymes catalyzing the first reactions in protein synthesis, in regulating telomere length and aging. We selected seryl tRNA synthetase (SerRS) since our previous studies discovered expanded functions of SerRS in the nucleus in addition to its canonical cytoplasmic role in protein synthesis. In this study, we revealed that overexpression of SerRS promoted cellular senescence and inhibited the growth of cervical tumor xenografts in mice by triggering the senescence of tumor cells. In the nucleus, SerRS directly bound to telomeric DNA repeats and tethered more POT1 proteins to telomeres through a direct interaction between the UNE-S domain of SerRS and the OB1 domain of POT1. We further demonstrated that SerRS-induced enrichment of POT1 prevented the recruitment of telomerase to telomeres, resulting in progressive telomere shortening. Our data suggested a possible molecular link between protein synthesis and telomere length control, the deregulation of which may be associated with aging and cancer.
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Affiliation(s)
- Yingxi Li
- School of Medicine, Nankai University, 94 Weijin Road, Tianjin, 300071 China
| | - Xiyang Li
- School of Medicine, Nankai University, 94 Weijin Road, Tianjin, 300071 China
| | - Mei Cao
- School of Medicine, Nankai University, 94 Weijin Road, Tianjin, 300071 China
| | - Yuke Jiang
- School of Medicine, Nankai University, 94 Weijin Road, Tianjin, 300071 China
| | - Jie Yan
- School of Medicine, Nankai University, 94 Weijin Road, Tianjin, 300071 China
| | - Ze Liu
- School of Medicine, Nankai University, 94 Weijin Road, Tianjin, 300071 China
| | - Rongcun Yang
- School of Medicine, Nankai University, 94 Weijin Road, Tianjin, 300071 China
| | - Xu Chen
- Tianjin Key Laboratory Human Development and Reproductive Regulation, Nankai University Affiliated Hospital of Obstetrics and Gynecology, Tianjin, China
| | - Peiqing Sun
- Department of Cancer Biology, Wake Forest Comprehensive Cancer Center, Wake Forest School of Medicine, Winston-Salem, NC USA
| | - Rong Xiang
- School of Medicine, Nankai University, 94 Weijin Road, Tianjin, 300071 China
| | - Longlong Wang
- School of Medicine, Nankai University, 94 Weijin Road, Tianjin, 300071 China
- Tianjin Key Laboratory Human Development and Reproductive Regulation, Nankai University Affiliated Hospital of Obstetrics and Gynecology, Tianjin, China
| | - Yi Shi
- School of Medicine, Nankai University, 94 Weijin Road, Tianjin, 300071 China
- Tianjin Key Laboratory Human Development and Reproductive Regulation, Nankai University Affiliated Hospital of Obstetrics and Gynecology, Tianjin, China
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104
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POT1-TPP1 differentially regulates telomerase via POT1 His266 and as a function of single-stranded telomere DNA length. Proc Natl Acad Sci U S A 2019; 116:23527-23533. [PMID: 31685617 PMCID: PMC6876245 DOI: 10.1073/pnas.1905381116] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Telomeres cap the ends of linear chromosomes and terminate in a single-stranded DNA (ssDNA) overhang recognized by POT1-TPP1 heterodimers to help regulate telomere length homeostasis. Here hydroxyl radical footprinting coupled with mass spectrometry was employed to probe protein-protein interactions and conformational changes involved in the assembly of telomere ssDNA substrates of differing lengths bound by POT1-TPP1 heterodimers. Our data identified environmental changes surrounding residue histidine 266 of POT1 that were dependent on telomere ssDNA substrate length. We further determined that the chronic lymphocytic leukemia-associated H266L substitution significantly reduced POT1-TPP1 binding to short ssDNA substrates; however, it only moderately impaired the heterodimer binding to long ssDNA substrates containing multiple protein binding sites. Additionally, we identified a telomerase inhibitory role when several native POT1-TPP1 proteins coat physiologically relevant lengths of telomere ssDNA. This POT1-TPP1 complex-mediated inhibition of telomerase is abrogated in the context of the POT1 H266L mutation, which leads to telomere overextension in a malignant cellular environment.
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105
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Pike AM, Strong MA, Ouyang JPT, Greider CW. TIN2 Functions with TPP1/POT1 To Stimulate Telomerase Processivity. Mol Cell Biol 2019; 39:e00593-18. [PMID: 31383750 PMCID: PMC6791651 DOI: 10.1128/mcb.00593-18] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2018] [Revised: 02/10/2019] [Accepted: 07/30/2019] [Indexed: 12/20/2022] Open
Abstract
TIN2 is an important regulator of telomere length, and mutations in TINF2, the gene encoding TIN2, cause short-telomere syndromes. While the genetics underscore the importance of TIN2, the mechanism through which TIN2 regulates telomere length remains unclear. Here, we tested the effects of human TIN2 on telomerase activity. We identified a new isoform in human cells, TIN2M, that is expressed at levels similar to those of previously studied TIN2 isoforms. All three TIN2 isoforms localized to and maintained telomere integrity in vivo, and localization was not disrupted by telomere syndrome mutations. Using direct telomerase activity assays, we discovered that TIN2 stimulated telomerase processivity in vitro All of the TIN2 isoforms stimulated telomerase to similar extents. Mutations in the TPP1 TEL patch abrogated this stimulation, suggesting that TIN2 functions with TPP1/POT1 to stimulate telomerase processivity. We conclude from our data and previously published work that TIN2/TPP1/POT1 is a functional shelterin subcomplex.
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Affiliation(s)
- Alexandra M Pike
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
- Graduate Program in Cellular and Molecular Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Margaret A Strong
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - John Paul T Ouyang
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
- Graduate Program in Biochemistry Cell and Molecular Biology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Carol W Greider
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
- Graduate Program in Cellular and Molecular Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
- Graduate Program in Biochemistry Cell and Molecular Biology, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
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106
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Barbero Barcenilla B, Shippen DE. Back to the future: The intimate and evolving connection between telomere-related factors and genotoxic stress. J Biol Chem 2019; 294:14803-14813. [PMID: 31434740 DOI: 10.1074/jbc.aw119.008145] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The conversion of circular genomes to linear chromosomes during molecular evolution required the invention of telomeres. This entailed the acquisition of factors necessary to fulfill two new requirements: the need to fully replicate terminal DNA sequences and the ability to distinguish chromosome ends from damaged DNA. Here we consider the multifaceted functions of factors recruited to perpetuate and stabilize telomeres. We discuss recent theories for how telomere factors evolved from existing cellular machineries and examine their engagement in nontelomeric functions such as DNA repair, replication, and transcriptional regulation. We highlight the remarkable versatility of protection of telomeres 1 (POT1) proteins that was fueled by gene duplication and divergence events that occurred independently across several eukaryotic lineages. Finally, we consider the relationship between oxidative stress and telomeres and the enigmatic role of telomere-associated proteins in mitochondria. These findings point to an evolving and intimate connection between telomeres and cellular physiology and the strong drive to maintain chromosome integrity.
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Affiliation(s)
- Borja Barbero Barcenilla
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843-2128
| | - Dorothy E Shippen
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843-2128
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107
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Niewisch MR, Savage SA. An update on the biology and management of dyskeratosis congenita and related telomere biology disorders. Expert Rev Hematol 2019; 12:1037-1052. [PMID: 31478401 DOI: 10.1080/17474086.2019.1662720] [Citation(s) in RCA: 99] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Introduction: Telomere biology disorders (TBDs) encompass a group of illnesses caused by germline mutations in genes regulating telomere maintenance, resulting in very short telomeres. Possible TBD manifestations range from complex multisystem disorders with onset in childhood such as dyskeratosis congenita (DC), Hoyeraal-Hreidarsson syndrome, Revesz syndrome and Coats plus to adults presenting with one or two DC-related features.Areas covered: The discovery of multiple genetic causes and inheritance patterns has led to the recognition of a spectrum of clinical features affecting multiple organ systems. Patients with DC and associated TBDs are at high risk of bone marrow failure, cancer, liver and pulmonary disease. Recently, vascular diseases, including pulmonary arteriovenous malformations and gastrointestinal telangiectasias, have been recognized as additional manifestations. Diagnostics include detection of very short leukocyte telomeres and germline genetic testing. Hematopoietic cell transplantation and lung transplantation are the only current therapeutic modalities but are complicated by numerous comorbidities. This review summarizes the pathophysiology underlying TBDs, associated clinical features, management recommendations and therapeutic options.Expert opinion: Understanding TBDs as complex, multisystem disorders with a heterogenous genetic background and diverse phenotypes, highlights the importance of clinical surveillance and the urgent need to develop new therapeutic strategies to improve health outcomes.
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Affiliation(s)
- Marena R Niewisch
- Clinical Genetics Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Sharon A Savage
- Clinical Genetics Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
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108
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Mennie AK, Moser BA, Hoyle A, Low RS, Tanaka K, Nakamura TM. Tpz1 TPP1 prevents telomerase activation and protects telomeres by modulating the Stn1-Ten1 complex in fission yeast. Commun Biol 2019; 2:297. [PMID: 31396577 PMCID: PMC6686008 DOI: 10.1038/s42003-019-0546-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Accepted: 07/15/2019] [Indexed: 12/24/2022] Open
Abstract
In both mammalian and fission yeast cells, conserved shelterin and CST (CTC1-STN1-TEN1) complexes play critical roles in protection of telomeres and regulation of telomerase, an enzyme required to overcome the end replication problem. However, molecular details that govern proper coordination among shelterin, CST, and telomerase have not yet been fully understood. Here, we establish a conserved SWSSS motif, located adjacent to the Lys242 SUMOylation site in the fission yeast shelterin subunit Tpz1, as a new functional regulatory element for telomere protection and telomere length homeostasis. The SWSSS motif works redundantly with Lys242 SUMOylation to promote binding of Stn1-Ten1 at telomere and sub-telomere regions to protect against single-strand annealing (SSA)-dependent telomere fusions, and to prevent telomerase accumulation at telomeres. In addition, we provide evidence that the SWSSS motif defines an unanticipated role of Tpz1 in limiting telomerase activation at telomeres to prevent uncontrolled telomere elongation.
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Affiliation(s)
- Amanda K. Mennie
- Department of Biochemistry and Molecular Genetics, College of Medicine, University of Illinois at Chicago, Chicago, IL 60607 USA
| | - Bettina A. Moser
- Department of Biochemistry and Molecular Genetics, College of Medicine, University of Illinois at Chicago, Chicago, IL 60607 USA
| | - Alice Hoyle
- Department of Biochemistry and Molecular Genetics, College of Medicine, University of Illinois at Chicago, Chicago, IL 60607 USA
| | - Ross S. Low
- Department of Biochemistry and Molecular Genetics, College of Medicine, University of Illinois at Chicago, Chicago, IL 60607 USA
- Present Address: Earlham Institute, Norwich Research Park, Norwich, NR4 7UZ United Kingdom
| | - Katsunori Tanaka
- Department of Bioscience, School of Science and Technology, Kwansei Gakuin University, Sanda, 669-1337 Japan
| | - Toru M. Nakamura
- Department of Biochemistry and Molecular Genetics, College of Medicine, University of Illinois at Chicago, Chicago, IL 60607 USA
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109
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Lee JH, Jung M, Hong J, Kim MK, Chung IK. Loss of RNA-binding protein HuR facilitates cellular senescence through posttranscriptional regulation of TIN2 mRNA. Nucleic Acids Res 2019; 46:4271-4285. [PMID: 29584879 PMCID: PMC5934620 DOI: 10.1093/nar/gky223] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Accepted: 03/15/2018] [Indexed: 02/07/2023] Open
Abstract
Cellular senescence can be induced by high levels of reactive oxygen species (ROS) produced by mitochondria. However, the mechanism by which elevated mitochondrial ROS levels are produced during replicative senescence is not yet fully understood. Here, we report that loss of the RNA-binding protein, human antigen R (HuR), during replicative senescence leads to an increase in ROS levels through enhanced mitochondrial localization of the telomeric protein TIN2. HuR binds to the 3′ untranslated region of TIN2 mRNA. This association decreases TIN2 protein levels by both destabilizing TIN2 mRNA and reducing its translation. Conversely, depletion of HuR levels enhances TIN2 expression, leading to increased mitochondrial targeting of TIN2. Mitochondrial localization of TIN2 increases ROS levels, which contributes to induction and maintenance of cellular senescence. Our findings provide compelling evidence for a novel role of HuR in controlling the process of cellular senescence by regulating TIN2-mediated mitochondrial ROS production, and for a useful therapeutic route for modulating intracellular ROS levels in treating both aging-related complications and cancer.
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Affiliation(s)
- Ji Hoon Lee
- Department of Systems Biology, College of Life Science and Biotechnology, Yonsei University, Seoul 03722, Korea
| | - Misun Jung
- Department of Integrated Omics for Biomedical Science, Yonsei University, Seoul 03722, Korea
| | - Juyeong Hong
- Department of Systems Biology, College of Life Science and Biotechnology, Yonsei University, Seoul 03722, Korea
| | - Mi Kyung Kim
- Department of Systems Biology, College of Life Science and Biotechnology, Yonsei University, Seoul 03722, Korea
| | - In Kwon Chung
- Department of Systems Biology, College of Life Science and Biotechnology, Yonsei University, Seoul 03722, Korea.,Department of Integrated Omics for Biomedical Science, Yonsei University, Seoul 03722, Korea
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110
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McNally EJ, Luncsford PJ, Armanios M. Long telomeres and cancer risk: the price of cellular immortality. J Clin Invest 2019; 129:3474-3481. [PMID: 31380804 PMCID: PMC6715353 DOI: 10.1172/jci120851] [Citation(s) in RCA: 89] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The distribution of telomere length in humans is broad, but it has finite upper and lower boundaries. Growing evidence shows that there are disease processes that are caused by both short and long telomere length extremes. The genetic basis of these short and long telomere syndromes may be linked to mutations in the same genes, such as the telomerase reverse transcriptase (TERT), but through differential effects on telomere length. Short telomere syndromes have a predominant degenerative phenotype marked by organ failure that most commonly manifests as pulmonary fibrosis and are associated with a relatively low cancer incidence. In contrast, insights from studies of cancer-prone families as well as genome-wide association studies (GWAS) have identified both rare and common variants that lengthen telomeres as being strongly associated with cancer risk. We have hypothesized that these cancers represent a long telomere syndrome that is associated with a high penetrance of cutaneous melanoma and chronic lymphocytic leukemia. In this Review, we will synthesize the clinical and human genetic observations with data from mouse models to define the role of telomeres in cancer etiology and biology.
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Affiliation(s)
| | | | - Mary Armanios
- Department of Oncology
- Telomere Center
- Sidney Kimmel Comprehensive Cancer Center, and
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
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111
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Janovič T, Stojaspal M, Veverka P, Horáková D, Hofr C. Human Telomere Repeat Binding Factor TRF1 Replaces TRF2 Bound to Shelterin Core Hub TIN2 when TPP1 Is Absent. J Mol Biol 2019; 431:3289-3301. [DOI: 10.1016/j.jmb.2019.05.038] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Revised: 05/22/2019] [Accepted: 05/23/2019] [Indexed: 12/17/2022]
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112
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The role of telomere-binding modulators in pluripotent stem cells. Protein Cell 2019; 11:60-70. [PMID: 31350723 PMCID: PMC6949317 DOI: 10.1007/s13238-019-0651-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Accepted: 05/07/2019] [Indexed: 01/24/2023] Open
Abstract
Pluripotent stem cells (PSCs) such as embryonic stem cells (ESCs), ESCs derived by somatic cell nuclear transfer (ntESCs), and induced pluripotent stem cells (iPSCs) have unlimited capacity for self-renewal and pluripotency and can give rise to all types of somatic cells. In order to maintain their self-renewal and pluripotency, PSCs need to preserve their telomere length and homeostasis. In recent years, increasing studies have shown that telomere reprogramming is essential for stem cell pluripotency maintenance and its induced pluripotency process. Telomere-associated proteins are not only required for telomere maintenance in both stem cells, their extra-telomeric functions have also been found to be critical as well. Here, we will discuss how telomeres and telomere-associated factors participate and regulate the maintenance of stem cell pluripotency.
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113
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Armstrong CA, Moiseeva V, Collopy LC, Pearson SR, Ullah TR, Xi ST, Martin J, Subramaniam S, Marelli S, Amelina H, Tomita K. Fission yeast Ccq1 is a modulator of telomerase activity. Nucleic Acids Res 2019; 46:704-716. [PMID: 29216371 PMCID: PMC5778466 DOI: 10.1093/nar/gkx1223] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Accepted: 11/27/2017] [Indexed: 01/05/2023] Open
Abstract
Shelterin, the telomeric protein complex, plays a crucial role in telomere homeostasis. In fission yeast, telomerase is recruited to chromosome ends by the shelterin component Tpz1 and its binding partner Ccq1, where telomerase binds to the 3' overhang to add telomeric repeats. Recruitment is initiated by the interaction of Ccq1 with the telomerase subunit Est1. However, how telomerase is released following elongation remains to be established. Here, we show that Ccq1 also has a role in the suppression of telomere elongation, when coupled with the Clr4 histone H3 methyl-transferase complex and the Clr3 histone deacetylase and nucleosome remodelling complex, SHREC. We have dissected the functions of Ccq1 by establishing a Ccq1-Est1 fusion system, which bypasses the telomerase recruitment step. We demonstrate that Ccq1 forms two distinct complexes for positive and negative telomerase regulation, with Est1 and Clr3 respectively. The negative form of Ccq1 promotes dissociation of Ccq1-telomerase from Tpz1, thereby restricting local telomerase activity. The Clr4 complex also has a negative regulation activity with Ccq1, independently of SHREC. Thus, we propose a model in which Ccq1-Est1 recruits telomerase to mediate telomere extension, whilst elongated telomeric DNA recruits Ccq1 with the chromatin-remodelling complexes, which in turn releases telomerase from the telomere.
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Affiliation(s)
- Christine A Armstrong
- Chromosome Maintenance Group, UCL Cancer Institute, University College London, London WC1E 6DD, UK
| | - Vera Moiseeva
- Chromosome Maintenance Group, UCL Cancer Institute, University College London, London WC1E 6DD, UK
| | - Laura C Collopy
- Chromosome Maintenance Group, UCL Cancer Institute, University College London, London WC1E 6DD, UK
| | - Siân R Pearson
- Chromosome Maintenance Group, UCL Cancer Institute, University College London, London WC1E 6DD, UK
| | - Tomalika R Ullah
- Chromosome Maintenance Group, UCL Cancer Institute, University College London, London WC1E 6DD, UK.,MSc Human Molecular Genetics, Faculty of Medicine, Imperial College London, London SW7 2AZ, UK
| | - Shidong T Xi
- Chromosome Maintenance Group, UCL Cancer Institute, University College London, London WC1E 6DD, UK.,Faculty of Life Sciences, University College London, London WC1E 6BT, UK
| | - Jennifer Martin
- Chromosome Maintenance Group, UCL Cancer Institute, University College London, London WC1E 6DD, UK.,MSc Human Molecular Genetics, Faculty of Medicine, Imperial College London, London SW7 2AZ, UK
| | - Shaan Subramaniam
- Chromosome Maintenance Group, UCL Cancer Institute, University College London, London WC1E 6DD, UK.,Faculty of Life Sciences, University College London, London WC1E 6BT, UK
| | - Sara Marelli
- Chromosome Maintenance Group, UCL Cancer Institute, University College London, London WC1E 6DD, UK
| | - Hanna Amelina
- Chromosome Maintenance Group, UCL Cancer Institute, University College London, London WC1E 6DD, UK
| | - Kazunori Tomita
- Chromosome Maintenance Group, UCL Cancer Institute, University College London, London WC1E 6DD, UK
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114
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Aureli S, Di Marino D, Raniolo S, Limongelli V. DDT - Drug Discovery Tool: a fast and intuitive graphics user interface for docking and molecular dynamics analysis. Bioinformatics 2019; 35:5328-5330. [PMID: 31304963 PMCID: PMC9887484 DOI: 10.1093/bioinformatics/btz543] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Revised: 05/23/2019] [Accepted: 07/11/2019] [Indexed: 02/02/2023] Open
Abstract
MOTIVATION The ligand/protein binding interaction is typically investigated by docking and molecular dynamics (MD) simulations. In particular, docking-based virtual screening (VS) is used to select the best ligands from database of thousands of compounds, while MD calculations assess the energy stability of the ligand/protein binding complexes. Considering the broad use of these techniques, it is of great demand to have one single software that allows a combined and fast analysis of VS and MD results. With this in mind, we have developed the Drug Discovery Tool (DDT) that is an intuitive graphics user interface able to provide structural data and physico-chemical information on the ligand/protein interaction. RESULTS DDT is designed as a plugin for the Visual Molecular Dynamics (VMD) software and is able to manage a large number of ligand/protein complexes obtained from AutoDock4 (AD4) docking calculations and MD simulations. DDT delivers four main outcomes: i) ligands ranking based on an energy score; ii) ligand ranking based on a ligands' conformation cluster analysis; iii) identification of the aminoacids forming the most occurrent interactions with the ligands; iv) plot of the ligands' center-of-mass coordinates in the Cartesian space. The flexibility of the software allows saving the best ligand/protein complexes using a number of user-defined options. AVAILABILITY AND IMPLEMENTATION DDT_site_1 (alternative DDT_site_2); the DDT tutorial movie is available here. SUPPLEMENTARY INFORMATION Supplementary data are available at Bioinformatics online.
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Affiliation(s)
- Simone Aureli
- Institute of Computational Science - Center for Computational Medicine in Cardiology, Faculty of Biomedical Sciences, Università della Svizzera italiana (USI), Lugano CH-6900, Switzerland
| | - Daniele Di Marino
- Institute of Computational Science - Center for Computational Medicine in Cardiology, Faculty of Biomedical Sciences, Università della Svizzera italiana (USI), Lugano CH-6900, Switzerland,Department of Life and Environmental Sciences, Polytechnic University of Marche, Ancona, Italy
| | - Stefano Raniolo
- Institute of Computational Science - Center for Computational Medicine in Cardiology, Faculty of Biomedical Sciences, Università della Svizzera italiana (USI), Lugano CH-6900, Switzerland
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Quantitative Biology of Human Shelterin and Telomerase: Searching for the Weakest Point. Int J Mol Sci 2019; 20:ijms20133186. [PMID: 31261825 PMCID: PMC6651453 DOI: 10.3390/ijms20133186] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Revised: 06/12/2019] [Accepted: 06/27/2019] [Indexed: 02/06/2023] Open
Abstract
The repetitive telomeric DNA at chromosome ends is protected from unwanted repair by telomere-associated proteins, which form the shelterin complex in mammals. Recent works have provided new insights into the mechanisms of how human shelterin assembles and recruits telomerase to telomeres. Inhibition of telomerase activity and telomerase recruitment to chromosome ends is a promising target for anticancer therapy. Here, we summarize results of quantitative assessments and newly emerged structural information along with the status of the most promising approaches to telomerase inhibition in cancer cells. We focus on the mechanism of shelterin assembly and the mechanisms of how shelterin affects telomerase recruitment to telomeres, addressing the conceptual dilemma of how shelterin allows telomerase action and regulates other essential processes. We evaluate how the identified critical interactions of telomerase and shelterin might be elucidated in future research of new anticancer strategies.
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Abstract
Telomeres are specialised structures at the end of linear chromosomes. They consist of tandem repeats of the hexanucleotide sequence TTAGGG, as well as a protein complex called shelterin. Together, they form a protective loop structure against chromosome fusion and degradation. Shortening or damage to telomeres and opening of the loop induce an uncapped state that triggers a DNA damage response resulting in senescence or apoptosis.Average telomere length, usually measured in human blood lymphocytes, was thought to be a biomarker for ageing, survival and mortality. However, it becomes obvious that regulation of telomere length is very complex and involves multiple processes. For example, the "end replication problem" during DNA replication as well as oxidative stress are responsible for the shortening of telomeres. In contrast, telomerase activity can potentially counteract telomere shortening when it is able to access and interact with telomeres. However, while highly active during development and in cancer cells, the enzyme is down-regulated in most human somatic cells with a few exceptions such as human lymphocytes. In addition, telomeres can be transcribed, and the transcription products called TERRA are involved in telomere length regulation.Thus, telomere length and their integrity are regulated at many different levels, and we only start to understand this process under conditions of increased oxidative stress, inflammation and during diseases as well as the ageing process.This chapter aims to describe our current state of knowledge on telomeres and telomerase and their regulation in order to better understand their role for the ageing process.
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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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118
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Telomere DNA G-quadruplex folding within actively extending human telomerase. Proc Natl Acad Sci U S A 2019; 116:9350-9359. [PMID: 31019071 DOI: 10.1073/pnas.1814777116] [Citation(s) in RCA: 76] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Telomerase reverse transcribes short guanine (G)-rich DNA repeat sequences from its internal RNA template to maintain telomere length. G-rich telomere DNA repeats readily fold into G-quadruplex (GQ) structures in vitro, and the presence of GQ-prone sequences throughout the genome introduces challenges to replication in vivo. Using a combination of ensemble and single-molecule telomerase assays, we discovered that GQ folding of the nascent DNA product during processive addition of multiple telomere repeats modulates the kinetics of telomerase catalysis and dissociation. Telomerase reactions performed with telomere DNA primers of varying sequence or using GQ-stabilizing K+ versus GQ-destabilizing Li+ salts yielded changes in DNA product profiles consistent with formation of GQ structures within the telomerase-DNA complex. Addition of the telomerase processivity factor POT1-TPP1 altered the DNA product profile, but was not sufficient to recover full activity in the presence of Li+ cations. This result suggests GQ folding synergizes with POT1-TPP1 to support telomerase function. Single-molecule Förster resonance energy transfer experiments reveal complex DNA structural dynamics during real-time catalysis in the presence of K+ but not Li+, supporting the notion of nascent product folding within the active telomerase complex. To explain the observed distributions of telomere products, we globally fit telomerase time-series data to a kinetic model that converges to a set of rate constants describing each successive telomere repeat addition cycle. Our results highlight the potential influence of the intrinsic folding properties of telomere DNA during telomerase catalysis, and provide a detailed characterization of GQ modulation of polymerase function.
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119
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Zhu J, Liu W, Chen C, Zhang H, Yue D, Li C, Zhang L, Gao L, Huo Y, Liu C, Giaccone G, Zhang B, Wang C. TPP1 OB-fold domain protein suppresses cell proliferation and induces cell apoptosis by inhibiting telomerase recruitment to telomeres in human lung cancer cells. J Cancer Res Clin Oncol 2019; 145:1509-1519. [PMID: 31016380 DOI: 10.1007/s00432-019-02921-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Accepted: 04/16/2019] [Indexed: 11/29/2022]
Abstract
PURPOSE Maintaining telomeres by recruiting telomerase-to-chromosome ends is essential for cancer cell survival. Inhibiting telomerase recruitment to telomeres represents a novel strategy for telomere-based lung cancer therapy. However, approaches for interrupting telomerase recruitment for cancer therapy still need to be explored. METHODS The telomere-binding protein TPP1 is responsible for recruiting telomerase to telomeres and synthesizing telomeres through the association between the oligosaccharide/oligonucleotide-binding (OB)-fold domain of TPP1 and telomerase reverse transcriptase. We overexpressed the TPP1 OB domain (TPP1-OB) by lentivirus infection in lung cancer cells. Telomere length was examined by Southern blot analysis of terminal restriction fragments. The effects of TPP1-OB on cell proliferation, the cell cycle, apoptosis, chemosensitivity, and tumor growth were evaluated in vitro and in vivo. RESULT TPP1-OB inhibited the recruitment of telomerase to telomeres and shortened telomere length by acting as a dominant-negative mutant of TPP1. TPP1-OB resulted in reduced cell proliferation, G1 cell cycle arrest, and increased cell apoptosis in lung cancer cells. Cell apoptosis occurred mainly through the caspase-3-dependent signaling pathway. TPP1-OB also suppressed anchorage-independent growth and tumor growth in vivo. Moreover, we demonstrated that TPP1-OB enhances the sensitivity of lung cancer cells to the chemotherapeutic drug paclitaxel. CONCLUSION Our results suggest that inhibiting TPP1-mediated telomerase recruitment by expressing the TPP1-OB domain is a potential novel strategy for telomere-targeted lung cancer therapy.
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Affiliation(s)
- Jinfang Zhu
- Department of Lung Cancer, Tianjin Lung Cancer Center, Tianjin Medical University Cancer Institute and Hospital, National Clinical Research Center for Cancer, Key Laboratory of Cancer Prevention and Therapy, Tianjin's Clinical Research Center for Cancer, Huan-Hu-Xi Road, Ti-Yuan-Bei, He Xi District, Tianjin, 300060, China
| | - Weiran Liu
- Department of Anesthesiology, Tianjin Medical University Cancer Institute and Hospital, National Clinical Research Center for Cancer, Key Laboratory of Cancer Prevention and Therapy, Tianjin's Clinical Research Center for Cancer, Tianjin, China
| | - Chen Chen
- Department of Lung Cancer, Tianjin Lung Cancer Center, Tianjin Medical University Cancer Institute and Hospital, National Clinical Research Center for Cancer, Key Laboratory of Cancer Prevention and Therapy, Tianjin's Clinical Research Center for Cancer, Huan-Hu-Xi Road, Ti-Yuan-Bei, He Xi District, Tianjin, 300060, China
| | - Hua Zhang
- Department of Lung Cancer, Tianjin Lung Cancer Center, Tianjin Medical University Cancer Institute and Hospital, National Clinical Research Center for Cancer, Key Laboratory of Cancer Prevention and Therapy, Tianjin's Clinical Research Center for Cancer, Huan-Hu-Xi Road, Ti-Yuan-Bei, He Xi District, Tianjin, 300060, China
| | - Dongsheng Yue
- Department of Lung Cancer, Tianjin Lung Cancer Center, Tianjin Medical University Cancer Institute and Hospital, National Clinical Research Center for Cancer, Key Laboratory of Cancer Prevention and Therapy, Tianjin's Clinical Research Center for Cancer, Huan-Hu-Xi Road, Ti-Yuan-Bei, He Xi District, Tianjin, 300060, China
| | - Chenguang Li
- Department of Lung Cancer, Tianjin Lung Cancer Center, Tianjin Medical University Cancer Institute and Hospital, National Clinical Research Center for Cancer, Key Laboratory of Cancer Prevention and Therapy, Tianjin's Clinical Research Center for Cancer, Huan-Hu-Xi Road, Ti-Yuan-Bei, He Xi District, Tianjin, 300060, China
| | - Lianmin Zhang
- Department of Lung Cancer, Tianjin Lung Cancer Center, Tianjin Medical University Cancer Institute and Hospital, National Clinical Research Center for Cancer, Key Laboratory of Cancer Prevention and Therapy, Tianjin's Clinical Research Center for Cancer, Huan-Hu-Xi Road, Ti-Yuan-Bei, He Xi District, Tianjin, 300060, China
| | - Liuwei Gao
- Department of Lung Cancer, Tianjin Lung Cancer Center, Tianjin Medical University Cancer Institute and Hospital, National Clinical Research Center for Cancer, Key Laboratory of Cancer Prevention and Therapy, Tianjin's Clinical Research Center for Cancer, Huan-Hu-Xi Road, Ti-Yuan-Bei, He Xi District, Tianjin, 300060, China
| | - Yansong Huo
- Department of Lung Cancer, Tianjin Lung Cancer Center, Tianjin Medical University Cancer Institute and Hospital, National Clinical Research Center for Cancer, Key Laboratory of Cancer Prevention and Therapy, Tianjin's Clinical Research Center for Cancer, Huan-Hu-Xi Road, Ti-Yuan-Bei, He Xi District, Tianjin, 300060, China
| | - Chang Liu
- Department of Lung Cancer, Tianjin Lung Cancer Center, Tianjin Medical University Cancer Institute and Hospital, National Clinical Research Center for Cancer, Key Laboratory of Cancer Prevention and Therapy, Tianjin's Clinical Research Center for Cancer, Huan-Hu-Xi Road, Ti-Yuan-Bei, He Xi District, Tianjin, 300060, China
| | - Giuseppe Giaccone
- Department of Lung Cancer, Tianjin Lung Cancer Center, Tianjin Medical University Cancer Institute and Hospital, National Clinical Research Center for Cancer, Key Laboratory of Cancer Prevention and Therapy, Tianjin's Clinical Research Center for Cancer, Huan-Hu-Xi Road, Ti-Yuan-Bei, He Xi District, Tianjin, 300060, China.,Georgetown University, Washington, DC, USA
| | - Bin Zhang
- Department of Lung Cancer, Tianjin Lung Cancer Center, Tianjin Medical University Cancer Institute and Hospital, National Clinical Research Center for Cancer, Key Laboratory of Cancer Prevention and Therapy, Tianjin's Clinical Research Center for Cancer, Huan-Hu-Xi Road, Ti-Yuan-Bei, He Xi District, Tianjin, 300060, China.
| | - Changli Wang
- Department of Lung Cancer, Tianjin Lung Cancer Center, Tianjin Medical University Cancer Institute and Hospital, National Clinical Research Center for Cancer, Key Laboratory of Cancer Prevention and Therapy, Tianjin's Clinical Research Center for Cancer, Huan-Hu-Xi Road, Ti-Yuan-Bei, He Xi District, Tianjin, 300060, China.
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120
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An N-terminal Flag-tag impairs TPP1 regulation of telomerase function. Biochem Biophys Res Commun 2019; 512:230-235. [PMID: 30885434 DOI: 10.1016/j.bbrc.2019.03.050] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Accepted: 03/08/2019] [Indexed: 10/27/2022]
Abstract
The shelterin protein complex protects natural chromosome ends from being recognized as DNA damage sites and also regulates the synthesis of telomeric repeats by telomerase. TPP1, a shelterin subunit that is essential for telomerase extension of telomeres, has been studied intensively in recent years. Many such studies utilize epitope tagged TPP1, but it is unclear how the tags may affect the multiple cellular functions of TPP1. Here we analyzed the effect of adding a 3x Flag epitope tag to the N- or C-terminus of TPP1. While the position of the tag did not affect TPP1's interaction within the shelterin complex or its localization to telomeres, the N-terminal Flag tag on TPP1 impaired telomerase function, resulting in reduced telomerase processivity in vitro and a failure to stimulate telomere elongation in vivo. The C-terminally Flag-tagged TPP1, in contrast, behaved similarly to untagged TPP1 in all functional aspects examined. These findings suggest that caution is required when utilizing epitope tagged TPP1 to study its regulation of telomerase function.
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121
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The Emerging Roles of TERRA in Telomere Maintenance and Genome Stability. Cells 2019; 8:cells8030246. [PMID: 30875900 PMCID: PMC6468625 DOI: 10.3390/cells8030246] [Citation(s) in RCA: 96] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Revised: 03/08/2019] [Accepted: 03/12/2019] [Indexed: 12/20/2022] Open
Abstract
The finding that transcription occurs at chromosome ends has opened new fields of study on the roles of telomeric transcripts in chromosome end maintenance and genome stability. Indeed, the ends of chromosomes are required to be protected from activation of DNA damage response and DNA repair pathways. Chromosome end protection is achieved by the activity of specific proteins that associate with chromosome ends, forming telomeres. Telomeres need to be constantly maintained as they are in a heterochromatic state and fold into specific structures (T-loops), which may hamper DNA replication. In addition, in the absence of maintenance mechanisms, chromosome ends shorten at every cell division due to limitations in the DNA replication machinery, which is unable to fully replicate the extremities of chromosomes. Altered telomere structure or critically short chromosome ends generate dysfunctional telomeres, ultimately leading to replicative senescence or chromosome instability. Telomere biology is thus implicated in multiple human diseases, including cancer. Emerging evidence indicates that a class of long noncoding RNAs transcribed at telomeres, known as TERRA for “TElomeric Repeat-containing RNA,” actively participates in the mechanisms regulating telomere maintenance and chromosome end protection. However, the molecular details of TERRA activities remain to be elucidated. In this review, we discuss recent findings on the emerging roles of TERRA in telomere maintenance and genome stability and their implications in human diseases.
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122
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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: 98] [Impact Index Per Article: 19.6] [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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123
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Telomeres in Plants and Humans: Not So Different, Not So Similar. Cells 2019; 8:cells8010058. [PMID: 30654521 PMCID: PMC6356271 DOI: 10.3390/cells8010058] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Revised: 01/07/2019] [Accepted: 01/07/2019] [Indexed: 01/01/2023] Open
Abstract
Parallel research on multiple model organisms shows that while some principles of telomere biology are conserved among all eukaryotic kingdoms, we also find some deviations that reflect different evolutionary paths and life strategies, which may have diversified after the establishment of telomerase as a primary mechanism for telomere maintenance. Much more than animals, plants have to cope with environmental stressors, including genotoxic factors, due to their sessile lifestyle. This is, in principle, made possible by an increased capacity and efficiency of the molecular systems ensuring maintenance of genome stability, as well as a higher tolerance to genome instability. Furthermore, plant ontogenesis differs from that of animals in which tissue differentiation and telomerase silencing occur during early embryonic development, and the “telomere clock” in somatic cells may act as a preventive measure against carcinogenesis. This does not happen in plants, where growth and ontogenesis occur through the serial division of apical meristems consisting of a small group of stem cells that generate a linear series of cells, which differentiate into an array of cell types that make a shoot and root. Flowers, as generative plant organs, initiate from the shoot apical meristem in mature plants which is incompatible with the human-like developmental telomere shortening. In this review, we discuss differences between human and plant telomere biology and the implications for aging, genome stability, and cell and organism survival. In particular, we provide a comprehensive comparative overview of telomere proteins acting in humans and in Arabidopsis thaliana model plant, and discuss distinct epigenetic features of telomeric chromatin in these species.
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124
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Zhu Y, Liu X, Ding X, Wang F, Geng X. Telomere and its role in the aging pathways: telomere shortening, cell senescence and mitochondria dysfunction. Biogerontology 2018; 20:1-16. [PMID: 30229407 DOI: 10.1007/s10522-018-9769-1] [Citation(s) in RCA: 114] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Accepted: 09/12/2018] [Indexed: 01/10/2023]
Abstract
Aging is a biological process characterized by a progressive functional decline in tissues and organs, which eventually leads to mortality. Telomeres, the repetitive DNA repeat sequences at the end of linear eukaryotic chromosomes protecting chromosome ends from degradation and illegitimate recombination, play a crucial role in cell fate and aging. Due to the mechanism of replication, telomeres shorten as cells proliferate, which consequently contributes to cellular senescence and mitochondrial dysfunction. Cells are the basic unit of organismal structure and function, and mitochondria are the powerhouse and metabolic center of cells. Therefore, cellular senescence and mitochondrial dysfunction would result in tissue or organ degeneration and dysfunction followed by somatic aging through multiple pathways. In this review, we summarized the main mechanisms of cellular senescence, mitochondrial malfunction and aging triggered by telomere attrition. Understanding the molecular mechanisms involved in the aging process may elicit new strategies for improving health and extending lifespan.
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Affiliation(s)
- Yukun Zhu
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Tianjin Medical University, Tianjin, 300070, China.,Key Laboratory of Immune Microenvironment and Disease (Ministry of Education), Tianjin Medical University, Tianjin, 300070, China
| | - Xuewen Liu
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Tianjin Medical University, Tianjin, 300070, China.,Key Laboratory of Immune Microenvironment and Disease (Ministry of Education), Tianjin Medical University, Tianjin, 300070, China
| | - Xuelu Ding
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Tianjin Medical University, Tianjin, 300070, China.,Key Laboratory of Immune Microenvironment and Disease (Ministry of Education), Tianjin Medical University, Tianjin, 300070, China
| | - Fei Wang
- Department of Neurology, General Hospital, Tianjin Medical University, Tianjin, 300052, China
| | - Xin Geng
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Tianjin Medical University, Tianjin, 300070, China. .,Key Laboratory of Immune Microenvironment and Disease (Ministry of Education), Tianjin Medical University, Tianjin, 300070, China.
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125
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Homozygous OB-fold variants in telomere protein TPP1 are associated with dyskeratosis congenita-like phenotypes. Blood 2018; 132:1349-1353. [PMID: 30064976 DOI: 10.1182/blood-2018-03-837799] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
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126
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Mersaoui SY, Wellinger RJ. Fine tuning the level of the Cdc13 telomere-capping protein for maximal chromosome stability performance. Curr Genet 2018; 65:109-118. [PMID: 30066139 DOI: 10.1007/s00294-018-0871-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Revised: 07/24/2018] [Accepted: 07/25/2018] [Indexed: 10/28/2022]
Abstract
Chromosome stability relies on an adequate length and complete replication of telomeres, the physical ends of chromosomes. Telomeres are composed of short direct repeat DNA and the associated nucleoprotein complex is essential for providing end-stability. In addition, the so-called end-replication problem of the conventional replication requires that telomeres be elongated by a special mechanism which, in virtually all organisms, is based by a reverse transcriptase, called telomerase. Although, at the conceptual level, telomere functions are highly similar in most organisms, the telomeric nucleoprotein composition appears to diverge significantly, in particular if it is compared between mammalian and budding yeast cells. However, over the last years, the CST complex has emerged as a central hub for telomere replication in most systems. Composed of three proteins, it is related to the highly conserved replication protein A complex, and in all systems studied, it coordinates telomerase-based telomere elongation with lagging-strand DNA synthesis. In budding yeast, the Cdc13 protein of this complex also is essential for telomerase recruitment and this specialisation is accompanied by additional regulatory adaptations. Based on recent results obtained in yeast, here, we review these issues and present an updated telomere replication hypothesis. We speculate that the similarities between systems far outweigh the differences, once we detach ourselves from the historic descriptions of the mechanisms in the various organisms.
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Affiliation(s)
- Sofiane Y Mersaoui
- Department of Microbiology and Infectious Diseases, Faculty of Medicine and Health Sciences, Université de Sherbrooke, 3201 Rue Jean Mignault, Sherbrooke, QC, J1E 4K8, Canada
| | - Raymund J Wellinger
- Department of Microbiology and Infectious Diseases, Faculty of Medicine and Health Sciences, Université de Sherbrooke, 3201 Rue Jean Mignault, Sherbrooke, QC, J1E 4K8, Canada.
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127
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Zhang Z, Zhong C, Yuan T, Zhou X, Zhao M, Qian H, Cheng W, Chen T. A hybridization chain reaction amplification strategy for fluorescence imaging of human telomerase activity in living cells. Methods Appl Fluoresc 2018; 6:045003. [PMID: 29924741 DOI: 10.1088/2050-6120/aacded] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
A hybridized chain reaction (HCR)-based biosensing method has been developed for the imaging detection of intracellular telomerase activity. The telomerase-targeting responder-transmitter DNA complex (HPT) consisting of telomerase primer sequence (HP) and a HCR initiator (trigger) is transfected into cell plasma. In the presence of telomerase, HPT can be recognized and extended, producing plenty of triggers which initiate HCR amplification reaction. Finally, a long nicked dsDNA with a lot of outstretched single chains was formed by hybridizing with Q of the reporter complex, generating an enhanced fluorescence signal. The developed biosensing approach can be used for the detection of telomerase activity in cell lysate with the detection limit of 578 cells/100 μl. In addition, this strategy has been successfully applied not only for the sensitive and specific imaging of telomerase activity in living cells but also for comparing of telomerase activity among different cell lines. Therefore, the method might become a potential alternative tool for telomerase-related cancer diagnosis and therapy in medical research and early clinical diagnosis.
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Affiliation(s)
- Zhiqian Zhang
- Key Laboratory of Clinical Laboratory Diagnostics (Ministry of Education), College of Laboratory Medicine, Chongqing Medical University, Chongqing 400016, People's Republic of China
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128
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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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129
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Smith ED, Garza-Gongora AG, MacQuarrie KL, Kosak ST. Interstitial telomeric loops and implications of the interaction between TRF2 and lamin A/C. Differentiation 2018; 102:19-26. [PMID: 29979997 DOI: 10.1016/j.diff.2018.06.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Revised: 06/11/2018] [Accepted: 06/12/2018] [Indexed: 11/19/2022]
Abstract
The protein-DNA complexes that compose the end of mammalian chromosomes-telomeres-serve to stabilize linear genomic DNA and are involved in cellular and organismal aging. One mechanism that protects telomeres from premature degradation is the formation of structures called t-loops, in which the single-stranded 3' overhang present at the terminal end of telomeres loops back and invades medial double-stranded telomeric DNA. We identified looped structures formed between terminal chromosome ends and interstitial telomeric sequences (ITSs), which are found throughout the human genome, that we have termed interstitial telomeric loops (ITLs). While they form in a TRF2-dependent manner similar to t-loops, ITLs further require the physical interaction of TRF2 with the nuclear intermediate filament protein lamin A/C. Our findings suggest that interactions between telomeres and the nucleoskeleton broadly impact genomic integrity, including telomere stability, chromosome structure, and chromosome fragility. Here, we review the roles of TRF2 and lamin A/C in telomere biology and consider how their interaction may relate telomere homeostasis to cellular and organismal aging.
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Affiliation(s)
- Erica D Smith
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - Arturo G Garza-Gongora
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - Kyle L MacQuarrie
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA; Division of Hematology, Oncology and Stem Cell Transplantation, Ann & Robert H. Lurie Children's Hospital of Chicago, USA
| | - Steven T Kosak
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA.
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130
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An Activity Switch in Human Telomerase Based on RNA Conformation and Shaped by TCAB1. Cell 2018; 174:218-230.e13. [PMID: 29804836 DOI: 10.1016/j.cell.2018.04.039] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Revised: 03/22/2018] [Accepted: 04/27/2018] [Indexed: 12/24/2022]
Abstract
Ribonucleoprotein enzymes require dynamic conformations of their RNA constituents for regulated catalysis. Human telomerase employs a non-coding RNA (hTR) with a bipartite arrangement of domains-a template-containing core and a distal three-way junction (CR4/5) that stimulates catalysis through unknown means. Here, we show that telomerase activity unexpectedly depends upon the holoenzyme protein TCAB1, which in turn controls conformation of CR4/5. Cells lacking TCAB1 exhibit a marked reduction in telomerase catalysis without affecting enzyme assembly. Instead, TCAB1 inactivation causes unfolding of CR4/5 helices that are required for catalysis and for association with the telomerase reverse-transcriptase (TERT). CR4/5 mutations derived from patients with telomere biology disorders provoke defects in catalysis and TERT binding similar to TCAB1 inactivation. These findings reveal a conformational "activity switch" in human telomerase RNA controlling catalysis and TERT engagement. The identification of two discrete catalytic states for telomerase suggests an intramolecular means for controlling telomerase in cancers and progenitor cells.
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131
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Jiang J, Wang Y, Sušac L, Chan H, Basu R, Zhou ZH, Feigon J. Structure of Telomerase with Telomeric DNA. Cell 2018; 173:1179-1190.e13. [PMID: 29775593 PMCID: PMC5995583 DOI: 10.1016/j.cell.2018.04.038] [Citation(s) in RCA: 102] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2018] [Revised: 04/22/2018] [Accepted: 04/26/2018] [Indexed: 01/05/2023]
Abstract
Telomerase is an RNA-protein complex (RNP) that extends telomeric DNA at the 3' ends of chromosomes using its telomerase reverse transcriptase (TERT) and integral template-containing telomerase RNA (TER). Its activity is a critical determinant of human health, affecting aging, cancer, and stem cell renewal. Lack of atomic models of telomerase, particularly one with DNA bound, has limited our mechanistic understanding of telomeric DNA repeat synthesis. We report the 4.8 Å resolution cryoelectron microscopy structure of active Tetrahymena telomerase bound to telomeric DNA. The catalytic core is an intricately interlocked structure of TERT and TER, including a previously structurally uncharacterized TERT domain that interacts with the TEN domain to physically enclose TER and regulate activity. This complete structure of a telomerase catalytic core and its interactions with telomeric DNA from the template to telomere-interacting p50-TEB complex provides unanticipated insights into telomerase assembly and catalytic cycle and a new paradigm for a reverse transcriptase RNP.
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Affiliation(s)
- Jiansen Jiang
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095, USA; Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles, Los Angeles, CA 90095, USA; California NanoSystems Institute, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Yaqiang Wang
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Lukas Sušac
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Henry Chan
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Ritwika Basu
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Z Hong Zhou
- Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles, Los Angeles, CA 90095, USA; California NanoSystems Institute, University of California, Los Angeles, Los Angeles, CA 90095, USA.
| | - Juli Feigon
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA 90095, USA.
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Matmati S, Vaurs M, Escandell JM, Maestroni L, Nakamura TM, Ferreira MG, Géli V, Coulon S. The fission yeast Stn1-Ten1 complex limits telomerase activity via its SUMO-interacting motif and promotes telomeres replication. SCIENCE ADVANCES 2018; 4:eaar2740. [PMID: 29774234 PMCID: PMC5955624 DOI: 10.1126/sciadv.aar2740] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2017] [Accepted: 03/29/2018] [Indexed: 06/01/2023]
Abstract
Mammalian CST (CTC1-STN1-TEN1) complex fulfills numerous functions including rescue of the stalled replication forks and termination of telomerase action. In fission yeast lacking the CTC1 ortholog, the Stn1-Ten1 complex restricts telomerase action via its sumoylation-mediated interaction with Tpz1TPP1. We identify a small ubiquitin-like modifier (SUMO)-interacting motif (SIM) in the carboxyl-terminal part of Stn1 and show that this domain is crucial for SUMO and Tpz1-SUMO interactions. Point mutations in the SIM (Stn1-226) lead to telomere elongation, impair Stn1-Ten1 recruitment to telomeres, and enhance telomerase binding, revealing that Stn1 SIM domain contributes to the inhibition of telomerase activity at chromosome ends. Our results suggest that Stn1-Ten1 promotes DNA synthesis at telomeres to limit single-strand DNA accumulation. We further demonstrate that Stn1 functions in the replication of telomeric and subtelomeric regions in a Taz1-independent manner. Genetic analysis reveals that misregulation of origin firing and/or telomerase inhibition circumvents the replication defects of the stn1-226 mutant. Together, our results show that the Stn1-Ten1 complex has a dual function at telomeres by limiting telomerase action and promoting chromosome end replication.
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Affiliation(s)
- Samah Matmati
- CRCM, CNRS, INSERM, Aix-Marseille Université, Institut Paoli-Calmettes, Equipe Labellisée Ligue, 27 Boulevard Lei Roure, Marseille, France
| | - Mélina Vaurs
- CRCM, CNRS, INSERM, Aix-Marseille Université, Institut Paoli-Calmettes, Equipe Labellisée Ligue, 27 Boulevard Lei Roure, Marseille, France
| | - José M. Escandell
- Telomere and Genome Stability Laboratory, Instituto Gulbenkian de Ciência, Oeiras, Portugal
| | - Laetitia Maestroni
- CRCM, CNRS, INSERM, Aix-Marseille Université, Institut Paoli-Calmettes, Equipe Labellisée Ligue, 27 Boulevard Lei Roure, Marseille, France
| | - Toru M. Nakamura
- Department of Biochemistry and Molecular Genetics, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Miguel G. Ferreira
- Telomere and Genome Stability Laboratory, Instituto Gulbenkian de Ciência, Oeiras, Portugal
- Institute for Research on Cancer and Aging, Nice, Faculty of Medicine, CNRS UMR7284, INSERM U1081, University of Nice Sophia Antipolis, Nice, France
| | - Vincent Géli
- CRCM, CNRS, INSERM, Aix-Marseille Université, Institut Paoli-Calmettes, Equipe Labellisée Ligue, 27 Boulevard Lei Roure, Marseille, France
| | - Stéphane Coulon
- CRCM, CNRS, INSERM, Aix-Marseille Université, Institut Paoli-Calmettes, Equipe Labellisée Ligue, 27 Boulevard Lei Roure, Marseille, France
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133
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Conklin QA, King BG, Zanesco AP, Lin J, Hamidi AB, Pokorny JJ, Álvarez-López MJ, Cosín-Tomás M, Huang C, Kaliman P, Epel ES, Saron CD. Insight meditation and telomere biology: The effects of intensive retreat and the moderating role of personality. Brain Behav Immun 2018. [PMID: 29518528 DOI: 10.1016/j.bbi.2018.03.003] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
A growing body of evidence suggests that meditation training may have a range of salubrious effects, including improved telomere regulation. Telomeres and the enzyme telomerase interact with a variety of molecular components to regulate cell-cycle signaling cascades, and are implicated in pathways linking psychological stress to disease. We investigated the effects of intensive meditation practice on these biomarkers by measuring changes in telomere length (TL), telomerase activity (TA), and telomere-related gene (TRG) expression during a 1-month residential Insight meditation retreat. Multilevel analyses revealed an apparent TL increase in the retreat group, compared to a group of experienced meditators, similarly comprised in age and gender, who were not on retreat. Moreover, personality traits predicted changes in TL, such that retreat participants highest in neuroticism and lowest in agreeableness demonstrated the greatest increases in TL. Changes observed in TRGs further suggest retreat-related improvements in telomere maintenance, including increases in Gar1 and HnRNPA1, which encode proteins that bind telomerase RNA and telomeric DNA. Although no group-level changes were observed in TA, retreat participants' TA levels at post-assessment were inversely related to several indices of retreat engagement and prior meditation experience. Neuroticism also predicted variation in TA across retreat. These findings suggest that meditation training in a retreat setting may have positive effects on telomere regulation, which are moderated by individual differences in personality and meditation experience. (ClinicalTrials.gov #NCT03056105).
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Affiliation(s)
- Quinn A Conklin
- Center for Mind and Brain, University of California, Davis, 267 Cousteau Place, Davis, CA 95618, United States; Department of Psychology, University of California, Davis, 135 Young Hall, Davis, CA 95616, United States.
| | - Brandon G King
- Center for Mind and Brain, University of California, Davis, 267 Cousteau Place, Davis, CA 95618, United States; Department of Psychology, University of California, Davis, 135 Young Hall, Davis, CA 95616, United States
| | - Anthony P Zanesco
- Center for Mind and Brain, University of California, Davis, 267 Cousteau Place, Davis, CA 95618, United States; Department of Psychology, University of California, Davis, 135 Young Hall, Davis, CA 95616, United States
| | - Jue Lin
- Department of Biochemistry & Biophysics, University of California, San Francisco, 600 16th St, San Francisco, CA 94158, United States
| | - Anahita B Hamidi
- Center for Mind and Brain, University of California, Davis, 267 Cousteau Place, Davis, CA 95618, United States; Center for Neuroscience, University of California, Davis, 1544 Newton Court, Davis, CA 95618, United States
| | - Jennifer J Pokorny
- Center for Mind and Brain, University of California, Davis, 267 Cousteau Place, Davis, CA 95618, United States
| | | | - Marta Cosín-Tomás
- Unit of Pharmacology, Institute of Biomedicine, University of Barcelona, Barcelona 08028, Spain
| | - Colin Huang
- Department of Biochemistry & Biophysics, University of California, San Francisco, 600 16th St, San Francisco, CA 94158, United States
| | - Perla Kaliman
- Center for Mind and Brain, University of California, Davis, 267 Cousteau Place, Davis, CA 95618, United States; Unit of Pharmacology, Institute of Biomedicine, University of Barcelona, Barcelona 08028, Spain
| | - Elissa S Epel
- Department of Psychiatry, University of California, San Francisco, 401 Parnassus Ave, San Francisco, CA 94131, United States
| | - Clifford D Saron
- Center for Mind and Brain, University of California, Davis, 267 Cousteau Place, Davis, CA 95618, United States; MIND Institute, University of California, Davis Medical Center, 2825 50th St, Sacramento, CA 95817, United States
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134
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Mariasina SS, Efimov SV, Petrova OA, Rodina EV, Malyavko AN, Zvereva MI, Klochkov VV, Dontsova OA, Polshakov VI. Chemical shift assignments and the secondary structure of the Est3 telomerase subunit in the yeast Hansenula polymorpha. BIOMOLECULAR NMR ASSIGNMENTS 2018; 12:57-62. [PMID: 28916982 DOI: 10.1007/s12104-017-9780-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Accepted: 09/13/2017] [Indexed: 06/07/2023]
Abstract
Telomerase is a multisubunit ribonucleoprotein enzyme that is essential for continuous cellular proliferation. A key role of telomerase in cancer and ageing makes it a promising target for the development of cancer therapies and treatments of other age-associated diseases, since telomerase allows unlimited proliferation potential of cells in the majority of cancer types. However, the structure and molecular mechanism of telomerase action are still poorly understood. In budding yeast, telomerase consists of the catalytic subunit, the telomerase reverse transcriptase or Est2 protein, telomerase RNA (TLC1) and two regulatory subunits, Est1 and Est3. Each of the four subunits is essential for in vivo telomerase function. Est3 interacts directly with Est1 and Est2, and stimulates Est2 catalytic activity. However, the exact role of the Est3 protein in telomerase function is still unknown. Determination of the structure, dynamic and functional properties of Est3 can bring new insights into the molecular mechanism of telomerase activity. Here we report nearly complete 1H, 13C and 15N resonance assignments of Est3 from the yeast Hansenula polymorpha. Analysis of the assigned chemical shifts allowed us to identify the protein's secondary structure and backbone dynamic properties. Structure-based sequence alignment revealed similarities in the structural organization of yeast Est3 and mammalian TPP1 proteins.
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Affiliation(s)
- Sofia S Mariasina
- Center for Magnetic Tomography and Spectroscopy, Faculty of Fundamental Medicine, M.V. Lomonosov Moscow State University, Moscow, Russia, 119991
- Department of Chemistry, M.V. Lomonosov Moscow State University, Moscow, Russia, 119991
| | - Sergey V Efimov
- NMR Laboratory, Institute of Physics, Kazan Federal University, 18 Kremlevskaya, Kazan, Russia, 420008
| | - Olga A Petrova
- A.N. Belozersky Institute of Physico-Chemical Biology, M.V. Lomonosov Moscow State University, Moscow, Russia, 119991
| | - Elena V Rodina
- Department of Chemistry, M.V. Lomonosov Moscow State University, Moscow, Russia, 119991
| | - Alexander N Malyavko
- Department of Chemistry, M.V. Lomonosov Moscow State University, Moscow, Russia, 119991
- Skolkovo Institute of Science and Technology, Moscow, Russia
| | - Maria I Zvereva
- Department of Chemistry, M.V. Lomonosov Moscow State University, Moscow, Russia, 119991
| | - Vladimir V Klochkov
- NMR Laboratory, Institute of Physics, Kazan Federal University, 18 Kremlevskaya, Kazan, Russia, 420008
| | - Olga A Dontsova
- Department of Chemistry, M.V. Lomonosov Moscow State University, Moscow, Russia, 119991
- A.N. Belozersky Institute of Physico-Chemical Biology, M.V. Lomonosov Moscow State University, Moscow, Russia, 119991
- Skolkovo Institute of Science and Technology, Moscow, Russia
| | - Vladimir I Polshakov
- Center for Magnetic Tomography and Spectroscopy, Faculty of Fundamental Medicine, M.V. Lomonosov Moscow State University, Moscow, Russia, 119991.
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135
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The role of telomere binding molecules for normal and abnormal hematopoiesis. Int J Hematol 2018; 107:646-655. [DOI: 10.1007/s12185-018-2432-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Accepted: 03/12/2018] [Indexed: 11/26/2022]
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136
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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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137
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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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138
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Telomeres: Implications for Cancer Development. Int J Mol Sci 2018; 19:ijms19010294. [PMID: 29351238 PMCID: PMC5796239 DOI: 10.3390/ijms19010294] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2017] [Revised: 01/12/2018] [Accepted: 01/16/2018] [Indexed: 12/31/2022] Open
Abstract
Telomeres facilitate the protection of natural ends of chromosomes from constitutive exposure to the DNA damage response (DDR). This is most likely achieved by a lariat structure that hides the linear telomeric DNA through protein-protein and protein-DNA interactions. The telomere shortening associated with DNA replication in the absence of a compensatory mechanism culminates in unmasked telomeres. Then, the subsequent activation of the DDR will define the fate of cells according to the functionality of cell cycle checkpoints. Dysfunctional telomeres can suppress cancer development by engaging replicative senescence or apoptotic pathways, but they can also promote tumour initiation. Studies in telomere dynamics and karyotype analysis underpin telomere crisis as a key event driving genomic instability. Significant attainment of telomerase or alternative lengthening of telomeres (ALT)-pathway to maintain telomere length may be permissive and required for clonal evolution of genomically-unstable cells during progression to malignancy. We summarise current knowledge of the role of telomeres in the maintenance of chromosomal stability and carcinogenesis.
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139
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Fiorini E, Santoni A, Colla S. Dysfunctional telomeres and hematological disorders. Differentiation 2018; 100:1-11. [PMID: 29331736 DOI: 10.1016/j.diff.2018.01.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Revised: 12/21/2017] [Accepted: 01/02/2018] [Indexed: 12/25/2022]
Abstract
Telomere biology disorders, which are characterized by telomerase activity haploinsufficiency and accelerated telomere shortening, most commonly manifest as degenerative diseases. Tissues with high rates of cell turnover, such as those in the hematopoietic system, are particularly vulnerable to defects in telomere maintenance genes that eventually culminate in bone marrow (BM) failure syndromes, in which the BM cannot produce sufficient new blood cells. Here, we review how telomere defects induce degenerative phenotypes across multiple organs, with particular focus on how they impact the hematopoietic stem and progenitor compartment and affect hematopoietic stem cell (HSC) self-renewal and differentiation. We also discuss how both the increased risk of myelodysplastic syndromes and other hematological malignancies that is associated with telomere disorders and the discovery of cancer-associated somatic mutations in the shelterin components challenge the conventional interpretation that telomere defects are cancer-protective rather than cancer-promoting.
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Affiliation(s)
- Elena Fiorini
- Department of Leukemia, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Andrea Santoni
- Department of Leukemia, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA
| | - Simona Colla
- Department of Leukemia, The University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.
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140
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Wang Y, Feigon J. Structural biology of telomerase and its interaction at telomeres. Curr Opin Struct Biol 2017; 47:77-87. [PMID: 28732250 PMCID: PMC5564310 DOI: 10.1016/j.sbi.2017.06.010] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Accepted: 06/29/2017] [Indexed: 12/21/2022]
Abstract
Telomerase is an RNP that synthesizes the 3' ends of linear chromosomes and is an important regulator of telomere length. It contains a single long non-coding telomerase RNA (TER), telomerase reverse transcriptase (TERT), and other proteins that vary among organisms. Recent progress in structural biology of telomerase includes reports of the first cryo-electron microscopy structure of telomerase, from Tetrahymena, new crystal structures of TERT domains, telomerase RNA structures and models, and identification in Tetrahymena telomerase holoenzyme of human homologues of telomere-associated proteins that have provided a more unified view of telomerase interaction at telomeres as well as insights into the role of telomerase RNA in activity and assembly.
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Affiliation(s)
- Yaqiang Wang
- Department of Chemistry and Biochemistry, University of California Los Angeles, Los Angeles, CA 90095-1569, USA
| | - Juli Feigon
- Department of Chemistry and Biochemistry, University of California Los Angeles, Los Angeles, CA 90095-1569, USA.
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141
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Hu C, Rai R, Huang C, Broton C, Long J, Xu Y, Xue J, Lei M, Chang S, Chen Y. Structural and functional analyses of the mammalian TIN2-TPP1-TRF2 telomeric complex. Cell Res 2017; 27:1485-1502. [PMID: 29160297 PMCID: PMC5717407 DOI: 10.1038/cr.2017.144] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2017] [Revised: 09/25/2017] [Accepted: 10/17/2017] [Indexed: 01/09/2023] Open
Abstract
Telomeres are nucleoprotein complexes that play essential roles in protecting chromosome ends. Mammalian telomeres consist of repetitive DNA sequences bound by the shelterin complex. In this complex, the POT1-TPP1 heterodimer binds to single-stranded telomeric DNAs, while TRF1 and TRF2-RAP1 interact with double-stranded telomeric DNAs. TIN2, the linchpin of this complex, simultaneously interacts with TRF1, TRF2, and TPP1 to mediate the stable assembly of the shelterin complex. However, the molecular mechanism by which TIN2 interacts with these proteins to orchestrate telomere protection remains poorly understood. Here, we report the crystal structure of the N-terminal domain of TIN2 in complex with TIN2-binding motifs from TPP1 and TRF2, revealing how TIN2 interacts cooperatively with TPP1 and TRF2. Unexpectedly, TIN2 contains a telomeric repeat factor homology (TRFH)-like domain that functions as a protein-protein interaction platform. Structure-based mutagenesis analyses suggest that TIN2 plays an important role in maintaining the stable shelterin complex required for proper telomere end protection.
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Affiliation(s)
- Chunyi Hu
- State Key Laboratory of Molecular Biology, National Center for Protein Science Shanghai, Shanghai Science Research Center, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences; University of Chinese Academy of Sciences, 333 Haike Road, Shanghai 201210, China
| | - Rekha Rai
- Department of Laboratory Medicine, Yale University School of Medicine, 330 Cedar St., New Haven, CT 06510 USA
| | - Chenhui Huang
- Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200011, China
- Shanghai Institute of Precision Medicine, Shanghai 200125, China
| | - Cayla Broton
- Department of Laboratory Medicine, Yale University School of Medicine, 330 Cedar St., New Haven, CT 06510 USA
| | - Juanjuan Long
- State Key Laboratory of Molecular Biology, National Center for Protein Science Shanghai, Shanghai Science Research Center, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences; University of Chinese Academy of Sciences, 333 Haike Road, Shanghai 201210, China
| | - Ying Xu
- State Key Laboratory of Molecular Biology, National Center for Protein Science Shanghai, Shanghai Science Research Center, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences; University of Chinese Academy of Sciences, 333 Haike Road, Shanghai 201210, China
| | - Jing Xue
- State Key Laboratory of Molecular Biology, National Center for Protein Science Shanghai, Shanghai Science Research Center, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences; University of Chinese Academy of Sciences, 333 Haike Road, Shanghai 201210, China
| | - Ming Lei
- Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200011, China
- Shanghai Institute of Precision Medicine, Shanghai 200125, China
- Key laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Sandy Chang
- Department of Laboratory Medicine, Yale University School of Medicine, 330 Cedar St., New Haven, CT 06510 USA
- Department of Pathology, Yale University School of Medicine, 330 Cedar St., New Haven, CT 06510 USA
- Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, 330 Cedar St., New Haven, CT 06510 USA
| | - Yong Chen
- State Key Laboratory of Molecular Biology, National Center for Protein Science Shanghai, Shanghai Science Research Center, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences; University of Chinese Academy of Sciences, 333 Haike Road, Shanghai 201210, China
- School of Life Science and Technology, ShanghaiTech University, 100 Haike Road, Shanghai 201210, China
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142
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Hsu M, Lue NF. The mechanisms of K. lactis Cdc13 in telomere DNA-binding and telomerase regulation. DNA Repair (Amst) 2017; 61:37-45. [PMID: 29197718 DOI: 10.1016/j.dnarep.2017.11.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2017] [Revised: 10/04/2017] [Accepted: 11/24/2017] [Indexed: 11/28/2022]
Abstract
Eukaryotic chromosome ends, or telomeres, are essential for genome stability and are protected by an intricate nucleoprotein assembly. Cdc13, the major single-strand telomere-binding protein in budding yeasts, mediates critical functions in both telomere protection and telomere elongation by telomerase. In particular, the interaction between S. cerevisiae Cdc13 and telomerase subunit Est1 has long served as a paradigm for telomerase regulation. However, despite extensive investigations, the role of this interaction in regulating telomerase recruitment or activation remains controversial. In addition, budding yeast telomere repeat sequences are extraordinarily variable and how Cdc13 orthologs recognize diverse repeats is not well understood. In this report, we examined these issues using an alternative model, K. lactis. We reconstituted a direct physical interaction between purified K. lactis Cdc13 and Est1, and by analyzing point mutations, we demonstrated a close correspondence between telomere maintenance defects in vivo and Cdc13-Est1 binding defects in vitro, thus supporting a purely recruitment function for this interaction in K. lactis. Because mutations in well aligned residues of Cdc13 and Est1 in S. cerevisiae and K. lactis do not cause identical defects, our results also point to significant evolutionary divergence in the Cdc13-Est1 interface. In addition, we found that K. lactic Cdc13, unlike previously characterized orthologs, recognizes an unusually long and non-G-rich target sequence, underscoring the flexibility of the Cdc13 DNA-binding domain. Analysis of K. lactis Cdc13 and Est1 thus broadens understanding of telomere and telomerase regulation in budding yeast.
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Affiliation(s)
- Min Hsu
- Department of Microbiology & Immunology, W. R. Hearst Microbiology Research Center, Weill Medical College of Cornell University, New York, NY 10065, USA
| | - Neal F Lue
- Department of Microbiology & Immunology, W. R. Hearst Microbiology Research Center, Weill Medical College of Cornell University, New York, NY 10065, USA; Sandra and Edward Meyer Cancer Center, Weill Cornell Medicine, New York, NY 10065, USA.
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143
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Ganduri S, Lue NF. STN1-POLA2 interaction provides a basis for primase-pol α stimulation by human STN1. Nucleic Acids Res 2017; 45:9455-9466. [PMID: 28934486 PMCID: PMC5766158 DOI: 10.1093/nar/gkx621] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Accepted: 07/06/2017] [Indexed: 01/12/2023] Open
Abstract
The CST (CTC1–STN1–TEN1) complex mediates critical functions in maintaining telomere DNA and overcoming genome-wide replication stress. A conserved biochemical function of the CST complex is its primase-Pol α (PP) stimulatory activity. In this report, we demonstrate the ability of purified human STN1 alone to promote PP activity in vitro. We show that this regulation is mediated primarily by the N-terminal OB fold of STN1, but does not require the DNA-binding activity of this domain. Rather, we observed a strong correlation between the PP-stimulatory activity of STN1 variants and their abilities to bind POLA2. Remarkably, the main binding target of STN1 in POLA2 is the latter's central OB fold domain. In the substrate-free structure of PP, this domain is positioned so as to block nucleic acid entry to the Pol α active site. Thus the STN1–POLA2 interaction may promote the necessary conformational change for nucleic acid delivery to Pol α and subsequent DNA synthesis. A disease-causing mutation in human STN1 engenders a selective defect in POLA2-binding and PP stimulation, indicating that these activities are critical for the in vivo function of STN1. Our findings have implications for the molecular mechanisms of PP, STN1 and STN1-related molecular pathology.
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Affiliation(s)
- Swapna Ganduri
- Department of Microbiology & Immunology, W. R. Hearst Microbiology Research Center, Weill Cornell Medical College, New York, NY 10065, USA
| | - Neal F Lue
- Department of Microbiology & Immunology, W. R. Hearst Microbiology Research Center, Weill Cornell Medical College, New York, NY 10065, USA.,Sandra and Edward Meyer Cancer Center, Weill Cornell Medicine, New York, NY 10065, USA
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144
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Wang S, Pike AM, Lee SS, Strong MA, Connelly CJ, Greider CW. BRD4 inhibitors block telomere elongation. Nucleic Acids Res 2017; 45:8403-8410. [PMID: 28854735 PMCID: PMC5737673 DOI: 10.1093/nar/gkx561] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Accepted: 06/22/2017] [Indexed: 12/25/2022] Open
Abstract
Cancer cells maintain telomere length equilibrium to avoid senescence and apoptosis induced by short telomeres, which trigger the DNA damage response. Limiting the potential for telomere maintenance in cancer cells has been long been proposed as a therapeutic target. Using an unbiased shRNA screen targeting known kinases, we identified bromodomain-containing protein 4 (BRD4) as a telomere length regulator. Four independent BRD4 inhibitors blocked telomere elongation, in a dose-dependent manner, in mouse cells overexpressing telomerase. Long-term treatment with BRD4 inhibitors caused telomere shortening in both mouse and human cells, suggesting BRD4 plays a role in telomere maintenance in vivo. Telomerase enzymatic activity was not directly affected by BRD4 inhibition. BRD4 is in clinical trials for a number of cancers, but its effects on telomere maintenance have not been previously investigated.
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Affiliation(s)
- Steven Wang
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.,Cellular and Molecular Medicine Graduate Program, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Alexandra M Pike
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.,Cellular and Molecular Medicine Graduate Program, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Stella S Lee
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Margaret A Strong
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Carla J Connelly
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Carol W Greider
- Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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145
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Lim CJ, Zaug AJ, Kim HJ, Cech TR. Reconstitution of human shelterin complexes reveals unexpected stoichiometry and dual pathways to enhance telomerase processivity. Nat Commun 2017; 8:1075. [PMID: 29057866 PMCID: PMC5651854 DOI: 10.1038/s41467-017-01313-w] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Accepted: 09/07/2017] [Indexed: 01/24/2023] Open
Abstract
The human shelterin proteins associate with telomeric DNA to confer telomere protection and length regulation. They are thought to form higher-order protein complexes for their functions, but studies of shelterin proteins have been mostly limited to pairs of proteins. Here we co-express various human shelterin proteins and find that they form defined multi-subunit complexes. A complex harboring both TRF2 and POT1 has the strongest binding affinity to telomeric DNA substrates comprised of double-stranded DNA with a 3′ single-stranded extension. TRF2 interacts with TIN2 with an unexpected 2:1 stoichiometry in the context of shelterin (RAP12:TRF22:TIN21:TPP11:POT11). Tethering of TPP1 to the telomere either via TRF2–TIN2 or via POT1 gives equivalent enhancement of telomerase processivity. We also identify a peptide region from TPP1 that is both critical and sufficient for TIN2 interaction. Our findings reveal new information about the architecture of human shelterin and how it performs its functions at telomeres. The human shelterin complex protects telomere ends from being recognized as damaged DNA sites and regulates telomere length in conjunction with telomerase. Here the authors establish the stoichiometries of human shelterin complexes of various compositions and show shelterin provides dual pathways to stimulate telomerase processivity.
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Affiliation(s)
- Ci Ji Lim
- Howard Hughes Medical Institute, University of Colorado BioFrontiers Institute, Boulder, CO, 80309, USA.,Department of Chemistry & Biochemistry, University of Colorado, Boulder, CO, 80309, USA
| | - Arthur J Zaug
- Howard Hughes Medical Institute, University of Colorado BioFrontiers Institute, Boulder, CO, 80309, USA.,Department of Chemistry & Biochemistry, University of Colorado, Boulder, CO, 80309, USA
| | - Hee Jin Kim
- Howard Hughes Medical Institute, University of Colorado BioFrontiers Institute, Boulder, CO, 80309, USA.,Department of Chemistry & Biochemistry, University of Colorado, Boulder, CO, 80309, USA
| | - Thomas R Cech
- Howard Hughes Medical Institute, University of Colorado BioFrontiers Institute, Boulder, CO, 80309, USA. .,Department of Chemistry & Biochemistry, University of Colorado, Boulder, CO, 80309, USA.
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146
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Abstract
PURPOSE OF REVIEW The activation of telomere maintenance pathways has long been regarded as a key hallmark of cancer and this has propelled the development of novel inhibitors of telomerase. In this review, we detail the background biology on telomere maintenance in health and disease, then concentrate on the recent preclinical and clinical development behind targeting telomerase in blood cancers. RECENT FINDINGS Preclinical and clinical studies have shown that imetelstat, a competitive inhibitor of telomerase, has activity in certain hematologic malignancies, in particular the myeloproliferative neoplasms and acute myeloid leukemia. SUMMARY Telomerase inhibition has shown remarkable efficacy in myeloid malignancies, and current and future preclinical and clinical studies are necessary to comprehensively investigate its underlying mechanism of action. Future work should identify the potential genetic susceptibilities to telomerase inhibition therapy, and evaluate rational combinations of telomerase inhibitors with chemotherapy and other novel agents. Robust preclinical evaluation is essential to best translate these new agents successfully into our clinical treatment algorithm for myeloid and other blood cancers.
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147
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Kim H, Li F, He Q, Deng T, Xu J, Jin F, Coarfa C, Putluri N, Liu D, Songyang Z. Systematic analysis of human telomeric dysfunction using inducible telosome/shelterin CRISPR/Cas9 knockout cells. Cell Discov 2017; 3:17034. [PMID: 28955502 PMCID: PMC5613224 DOI: 10.1038/celldisc.2017.34] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Accepted: 07/27/2017] [Indexed: 01/14/2023] Open
Abstract
CRISPR/Cas9 technology enables efficient loss-of-function analysis of human genes using
somatic cells. Studies of essential genes, however, require conditional knockout (KO)
cells. Here, we describe the generation of inducible CRISPR KO human cell lines for the
subunits of the telosome/shelterin complex, TRF1, TRF2, RAP1, TIN2, TPP1 and POT1, which
directly interact with telomeres or can bind to telomeres through association with other
subunits. Homozygous inactivation of several subunits is lethal in mice, and most
loss-of-function studies of human telomere regulators have relied on RNA
interference-mediated gene knockdown, which suffers its own limitations. Our inducible
CRISPR approach has allowed us to more expediently obtain large numbers of KO cells in
which essential telomere regulators have been inactivated for biochemical and molecular
studies. Our systematic analysis revealed functional differences between human and mouse
telomeric proteins in DNA damage responses, telomere length and metabolic control,
providing new insights into how human telomeres are maintained.
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Affiliation(s)
- Hyeung Kim
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX, USA
| | - Feng Li
- Key Laboratory of Gene Engineering of the Ministry of Education and State Key Laboratory for Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Quanyuan He
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX, USA
| | - Tingting Deng
- Key Laboratory of Gene Engineering of the Ministry of Education and State Key Laboratory for Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Jun Xu
- Cell-Based Assay Screening Service Core, Baylor College of Medicine, Houston, TX, USA
| | - Feng Jin
- Department of Molecular and Cellular Biology and Advanced Technology Core, Baylor College of Medicine, Houston, TX, USA
| | - Cristian Coarfa
- Department of Molecular and Cellular Biology and Advanced Technology Core, Baylor College of Medicine, Houston, TX, USA
| | - Nagireddy Putluri
- Department of Molecular and Cellular Biology and Advanced Technology Core, Baylor College of Medicine, Houston, TX, USA
| | - Dan Liu
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX, USA.,Cell-Based Assay Screening Service Core, Baylor College of Medicine, Houston, TX, USA
| | - Zhou Songyang
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX, USA.,Key Laboratory of Gene Engineering of the Ministry of Education and State Key Laboratory for Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
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148
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Bisht K, Grill S, Graniel J, Nandakumar J. A lentivirus-free inducible CRISPR-Cas9 system for efficient targeting of human genes. Anal Biochem 2017; 530:40-49. [PMID: 28477963 PMCID: PMC5501077 DOI: 10.1016/j.ab.2017.05.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Revised: 04/11/2017] [Accepted: 05/01/2017] [Indexed: 01/29/2023]
Abstract
CRISPR-Cas9 is a cutting-edge tool for modifying genomes. The efficacy with which Cas9 recognizes its target has revolutionized the engineering of knockouts. However this efficacy complicates the knocking out of important genes in cultured cells. Unedited cells holding a survival advantage within an edited population can confound the knockout phenotype. Here we develop a HeLa-based system that overcomes this limitation, incorporating several attractive features. First, we use Flp-recombinase to generate clones stably integrated for Cas9 and guide RNAs, eliminating the possibility of unedited cells. Second, Cas9 can be induced uniformly in the clonal cultures using doxycycline to measure the knockout phenotype. Third, two genes can be simultaneously knocked out using this approach. Finally, by not involving lentiviruses, our method is appealing to a broad research audience. Using this methodology we generated an inducible AGO2-knockout cell line showing normal RNA interference in the absence of doxycycline. Upon induction of Cas9, the AGO2 locus was cleaved, the AGO2 protein was depleted, and RNA interference was compromised. In addition to generating inducible knockouts, our technology can be adapted to improve other applications of Cas9, including transcriptional/epigenetic modulation and visualization of cellular DNA loci.
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Affiliation(s)
- Kamlesh Bisht
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Sherilyn Grill
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Jacqueline Graniel
- 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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149
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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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150
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Abstract
Telomerase is an RNA-protein complex that extends the 3' ends of linear chromosomes, using a unique telomerase reverse transcriptase (TERT) and template in the telomerase RNA (TR), thereby helping to maintain genome integrity. TR assembles with TERT and species-specific proteins, and telomerase function in vivo requires interaction with telomere-associated proteins. Over the past two decades, structures of domains of TR and TERT as well as other telomerase- and telomere-interacting proteins have provided insights into telomerase function. A recently reported 9-Å cryo-electron microscopy map of the Tetrahymena telomerase holoenzyme has provided a framework for understanding how TR, TERT, and other proteins from ciliate as well as vertebrate telomerase fit and function together as well as unexpected insight into telomerase interaction at telomeres. Here we review progress in understanding the structural basis of human and Tetrahymena telomerase activity, assembly, and interactions.
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Affiliation(s)
- Henry Chan
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095-1569; , ,
| | - Yaqiang Wang
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095-1569; , ,
| | - Juli Feigon
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095-1569; , ,
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