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Li P, Gai X, Li Q, Yang Q, Yu X. DNA-PK participates in pre-rRNA biogenesis independent of DNA double-strand break repair. Nucleic Acids Res 2024:gkae316. [PMID: 38682589 DOI: 10.1093/nar/gkae316] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Revised: 04/06/2024] [Accepted: 04/16/2024] [Indexed: 05/01/2024] Open
Abstract
Although DNA-PK inhibitors (DNA-PK-i) have been applied in clinical trials for cancer treatment, the biomarkers and mechanism of action of DNA-PK-i in tumor cell suppression remain unclear. Here, we observed that a low dose of DNA-PK-i and PARP inhibitor (PARP-i) synthetically suppresses BRCA-deficient tumor cells without inducing DNA double-strand breaks (DSBs). Instead, we found that a fraction of DNA-PK localized inside of nucleoli, where we did not observe obvious DSBs. Moreover, the Ku proteins recognize pre-rRNA that facilitates DNA-PKcs autophosphorylation independent of DNA damage. Ribosomal proteins are also phosphorylated by DNA-PK, which regulates pre-rRNA biogenesis. In addition, DNA-PK-i acts together with PARP-i to suppress pre-rRNA biogenesis and tumor cell growth. Collectively, our studies reveal a DNA damage repair-independent role of DNA-PK-i in tumor suppression.
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Affiliation(s)
- Peng Li
- Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, Zhejiang, China
- School of Life Sciences, Westlake University, Hangzhou, Zhejiang, China
- Institute of Basic Medical Sciences, Westlake Institute for Advanced Study, Hangzhou, Zhejiang, China
| | - Xiaochen Gai
- Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, Zhejiang, China
- School of Life Sciences, Westlake University, Hangzhou, Zhejiang, China
- Institute of Basic Medical Sciences, Westlake Institute for Advanced Study, Hangzhou, Zhejiang, China
| | - Qilin Li
- Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, Zhejiang, China
- School of Life Sciences, Westlake University, Hangzhou, Zhejiang, China
- Institute of Basic Medical Sciences, Westlake Institute for Advanced Study, Hangzhou, Zhejiang, China
| | - Qianqian Yang
- Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, Zhejiang, China
- School of Life Sciences, Westlake University, Hangzhou, Zhejiang, China
- Institute of Basic Medical Sciences, Westlake Institute for Advanced Study, Hangzhou, Zhejiang, China
| | - Xiaochun Yu
- Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou, Zhejiang, China
- School of Life Sciences, Westlake University, Hangzhou, Zhejiang, China
- Institute of Basic Medical Sciences, Westlake Institute for Advanced Study, Hangzhou, Zhejiang, China
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2
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Neumann H, Bartle L, Bonnell E, Wellinger RJ. Ratcheted transport and sequential assembly of the yeast telomerase RNP. Cell Rep 2023; 42:113565. [PMID: 38096049 DOI: 10.1016/j.celrep.2023.113565] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Revised: 10/04/2023] [Accepted: 11/22/2023] [Indexed: 12/30/2023] Open
Abstract
The telomerase ribonucleoprotein particle (RNP) replenishes telomeric DNA and minimally requires an RNA component and a catalytic protein subunit. However, telomerase RNP maturation is an intricate process occurring in several subcellular compartments and is incompletely understood. Here, we report how the co-transcriptional association of key telomerase components and nuclear export factors leads to an export-competent, but inactive, RNP. Export is dependent on the 5' cap, the 3' extension of unprocessed telomerase RNA, and protein associations. When the RNP reaches the cytoplasm, an extensive protein swap occurs, the RNA is trimmed to its mature length, and the essential catalytic Est2 protein joins the RNP. This mature and active complex is then reimported into the nucleus as its final destination and last processing steps. The irreversible processing events on the RNA thus support a ratchet-type model of telomerase maturation, with only a single nucleo-cytoplasmic cycle that is essential for the assembly of mature telomerase.
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Affiliation(s)
- Hannah Neumann
- Department of Microbiology and Infectious Diseases, Faculty of Medicine and Health Sciences, Université de Sherbrooke, 3201 Rue Jean Mignault, Sherbrooke, QC J1E 4K8, Canada
| | - Louise Bartle
- Department of Microbiology and Infectious Diseases, Faculty of Medicine and Health Sciences, Université de Sherbrooke, 3201 Rue Jean Mignault, Sherbrooke, QC J1E 4K8, Canada; Research Center on Aging (CdRV), 1036 rue Belvedere Sud, Sherbrooke, QC J1H 4C4, Canada
| | - Erin Bonnell
- 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; Research Center on Aging (CdRV), 1036 rue Belvedere Sud, Sherbrooke, QC J1H 4C4, Canada.
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3
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Li B. Telomere maintenance in African trypanosomes. Front Mol Biosci 2023; 10:1302557. [PMID: 38074093 PMCID: PMC10704157 DOI: 10.3389/fmolb.2023.1302557] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Accepted: 11/15/2023] [Indexed: 02/12/2024] Open
Abstract
Telomere maintenance is essential for genome integrity and chromosome stability in eukaryotic cells harboring linear chromosomes, as telomere forms a specialized structure to mask the natural chromosome ends from DNA damage repair machineries and to prevent nucleolytic degradation of the telomeric DNA. In Trypanosoma brucei and several other microbial pathogens, virulence genes involved in antigenic variation, a key pathogenesis mechanism essential for host immune evasion and long-term infections, are located at subtelomeres, and expression and switching of these major surface antigens are regulated by telomere proteins and the telomere structure. Therefore, understanding telomere maintenance mechanisms and how these pathogens achieve a balance between stability and plasticity at telomere/subtelomere will help develop better means to eradicate human diseases caused by these pathogens. Telomere replication faces several challenges, and the "end replication problem" is a key obstacle that can cause progressive telomere shortening in proliferating cells. To overcome this challenge, most eukaryotes use telomerase to extend the G-rich telomere strand. In addition, a number of telomere proteins use sophisticated mechanisms to coordinate the telomerase-mediated de novo telomere G-strand synthesis and the telomere C-strand fill-in, which has been extensively studied in mammalian cells. However, we recently discovered that trypanosomes lack many telomere proteins identified in its mammalian host that are critical for telomere end processing. Rather, T. brucei uses a unique DNA polymerase, PolIE that belongs to the DNA polymerase A family (E. coli DNA PolI family), to coordinate the telomere G- and C-strand syntheses. In this review, I will first briefly summarize current understanding of telomere end processing in mammals. Subsequently, I will describe PolIE-mediated coordination of telomere G- and C-strand synthesis in T. brucei and implication of this recent discovery.
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Affiliation(s)
- Bibo Li
- Center for Gene Regulation in Health and Disease, Department of Biological, Geological, and Environmental Sciences, College of Arts and Sciences, Cleveland State University, Cleveland, OH, United States
- Case Comprehensive Cancer Center, Case Western Reserve University, Cleveland, OH, United States
- Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, United States
- Center for RNA Science and Therapeutics, Case Western Reserve University, Cleveland, OH, United States
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4
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Post-Transcriptional and Post-Translational Modifications in Telomerase Biogenesis and Recruitment to Telomeres. Int J Mol Sci 2023; 24:ijms24055027. [PMID: 36902458 PMCID: PMC10003056 DOI: 10.3390/ijms24055027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Revised: 03/02/2023] [Accepted: 03/03/2023] [Indexed: 03/08/2023] Open
Abstract
Telomere length is associated with the proliferative potential of cells. Telomerase is an enzyme that elongates telomeres throughout the entire lifespan of an organism in stem cells, germ cells, and cells of constantly renewed tissues. It is activated during cellular division, including regeneration and immune responses. The biogenesis of telomerase components and their assembly and functional localization to the telomere is a complex system regulated at multiple levels, where each step must be tuned to the cellular requirements. Any defect in the function or localization of the components of the telomerase biogenesis and functional system will affect the maintenance of telomere length, which is critical to the processes of regeneration, immune response, embryonic development, and cancer progression. An understanding of the regulatory mechanisms of telomerase biogenesis and activity is necessary for the development of approaches toward manipulating telomerase to influence these processes. The present review focuses on the molecular mechanisms involved in the major steps of telomerase regulation and the role of post-transcriptional and post-translational modifications in telomerase biogenesis and function in yeast and vertebrates.
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Vulsteke JB, Smith V, Bonroy C, Derua R, Blockmans D, De Haes P, Vanderschueren S, Lenaerts JL, Claeys KG, Wuyts WA, Verschueren P, Vanhandsaeme G, Piette Y, De Langhe E, Bossuyt X. Identification of new telomere- and telomerase-associated autoantigens in systemic sclerosis. J Autoimmun 2023; 135:102988. [PMID: 36634459 DOI: 10.1016/j.jaut.2022.102988] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Accepted: 12/16/2022] [Indexed: 01/12/2023]
Abstract
PURPOSE In up to 20% of patients with systemic sclerosis (SSc) no known autoantibody specificity can be identified. Recently discovered autoantigens, such as telomeric repeat binding factor 1 (TERF1), as well as established autoantigens, like RuvBL1/2, are associated with telomere and telomerase biology. We aimed to identify new telomere- and telomerase-associated autoantigens in patients with SSc without known autoantibody specificity. METHODS Unlabelled protein immunoprecipitation combined with gel-free liquid chromatography-tandem mass spectrometry (IP-MS) was performed with sera of 106 patients with SSc from two tertiary referral centres that had a nuclear pattern on HEp-2 indirect immunofluorescence without previously identified autoantibody. Telomere- or telomerase-associated proteins or protein complexes precipitated by individual sera were identified. Candidate autoantigens were confirmed through immunoprecipitation-western blot (IP-WB). A custom Luminex xMAP assay for 5 proteins was evaluated with sera from persons with SSc (n = 467), other systemic autoimmune rheumatic diseases (n = 923), non-rheumatic disease controls (n = 187) and healthy controls (n = 199). RESULTS Eight telomere- and telomerase-associated autoantigens were identified in a total of 11 index patients, including the THO complex (n = 3, all with interstitial lung disease and two with cardiac involvement), telomeric repeat-binding factor 2 (TERF2, n = 1), homeobox-containing protein 1 (HMBOX1, n = 2), regulator of chromosome condensation 1 (RCC1, n = 1), nucleolar and coiled-body phosphoprotein 1 (NOLC1, n = 1), dyskerin (DKC1, n = 1), probable 28S rRNA (cytosine(4447)-C(5))-methyltransferase (NOP2, n = 1) and nuclear valosin-containing protein-like (NVL, n = 2). A Luminex xMAP assay for THO complex subunit 1 (THOC1), TERF2, NOLC1, NOP2 and NVL revealed high reactivity in all index patients, but also in other patients with SSc and disease controls. However, the reactivity by xMAP assay in these other patients was not confirmed by IP-WB. CONCLUSION IP-MS revealed key telomere- and telomerase-associated proteins and protein complexes as autoantigens in patients with SSc.
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Affiliation(s)
- Jean-Baptiste Vulsteke
- KU Leuven, Department of Development and Regeneration, Skeletal Biology and Engineering Research Center, Leuven, Belgium; Rheumatology, University Hospitals Leuven, Leuven, Belgium
| | - Vanessa Smith
- Ghent University, Department of Internal Medicine, Ghent, Belgium; Unit for Molecular Immunology and Inflammation, VIB Inflammation Research Center (IRC), Ghent, Belgium; Rheumatology, Ghent University Hospital, Ghent, Belgium; European Reference Network on Rare and Complex Connective Tissue and Musculoskeletal Diseases (ERN ReCONNET), Belgium
| | - Carolien Bonroy
- Ghent University, Department of Diagnostic Sciences, Ghent, Belgium; Laboratory Medicine, Ghent University Hospital, Ghent, Belgium
| | - Rita Derua
- KU Leuven, Department of Cellular and Molecular Medicine, Laboratory of Protein Phosphorylation and Proteomics, Leuven, Belgium; KU Leuven, SyBioMa, Leuven, Belgium
| | - Daniel Blockmans
- KU Leuven, Department of Microbiology, Immunology and Transplantation, Laboratory for Clinical Infectious and Inflammatory Disorders, Leuven, Belgium; General Internal Medicine, University Hospitals Leuven, Leuven, Belgium
| | - Petra De Haes
- KU Leuven, Department of Microbiology, Immunology and Transplantation, Leuven, Belgium; Dermatology, University Hospitals Leuven, Leuven, Belgium
| | - Steven Vanderschueren
- KU Leuven, Department of Microbiology, Immunology and Transplantation, Laboratory for Clinical Infectious and Inflammatory Disorders, Leuven, Belgium; General Internal Medicine, University Hospitals Leuven, Leuven, Belgium; European Reference Network on Rare Immunodeficiency, Autoinflammatory and Autoimmune Diseases (ERN RITA), Belgium
| | - Jan L Lenaerts
- Rheumatology, University Hospitals Leuven, Leuven, Belgium
| | - Kristl G Claeys
- KU Leuven, Department of Neurosciences, Laboratory for Muscle Diseases and Neuropathies, Neurology, University Hospitals Leuven, Leuven, Belgium; European Reference Network on Rare Neuromuscular Diseases (ERN EURO-NMD), Belgium
| | - Wim A Wuyts
- KU Leuven, Department of Chronic Diseases and Metabolism, Laboratory of Respiratory Diseases and Thoracic Surgery, Unit for Interstitial Lung Diseases, Respiratory Medicine, University Hospitals Leuven, Leuven, Belgium; European Reference Network on Rare Respiratory Diseases (ERN LUNG), Belgium
| | - Patrick Verschueren
- KU Leuven, Department of Development and Regeneration, Skeletal Biology and Engineering Research Center, Leuven, Belgium; Rheumatology, University Hospitals Leuven, Leuven, Belgium
| | | | - Yves Piette
- Ghent University, Department of Internal Medicine, Ghent, Belgium; Rheumatology, Ghent University Hospital, Ghent, Belgium
| | - Ellen De Langhe
- KU Leuven, Department of Development and Regeneration, Skeletal Biology and Engineering Research Center, Leuven, Belgium; Rheumatology, University Hospitals Leuven, Leuven, Belgium; European Reference Network on Rare and Complex Connective Tissue and Musculoskeletal Diseases (ERN ReCONNET), Belgium; European Reference Network on Rare Immunodeficiency, Autoinflammatory and Autoimmune Diseases (ERN RITA), Belgium
| | - Xavier Bossuyt
- KU Leuven, Department of Microbiology, Immunology and Transplantation, Clinical and Diagnostic Immunology, Leuven, Belgium; Laboratory Medicine, University Hospitals Leuven, Leuven, Belgium.
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6
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Udroiu I, Marinaccio J, Sgura A. Many Functions of Telomerase Components: Certainties, Doubts, and Inconsistencies. Int J Mol Sci 2022; 23:ijms232315189. [PMID: 36499514 PMCID: PMC9736166 DOI: 10.3390/ijms232315189] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Revised: 11/23/2022] [Accepted: 11/29/2022] [Indexed: 12/12/2022] Open
Abstract
A growing number of studies have evidenced non-telomeric functions of "telomerase". Almost all of them, however, investigated the non-canonical effects of the catalytic subunit TERT, and not the telomerase ribonucleoprotein holoenzyme. These functions mainly comprise signal transduction, gene regulation and the increase of anti-oxidative systems. Although less studied, TERC (the RNA component of telomerase) has also been shown to be involved in gene regulation, as well as other functions. All this has led to the publication of many reviews on the subject, which, however, are often disseminating personal interpretations of experimental studies of other researchers as original proofs. Indeed, while some functions such as gene regulation seem ascertained, especially because mechanistic findings have been provided, other ones remain dubious and/or are contradicted by other direct or indirect evidence (e.g., telomerase activity at double-strand break site, RNA polymerase activity of TERT, translation of TERC, mitochondrion-processed TERC). In a critical study of the primary evidence so far obtained, we show those functions for which there is consensus, those showing contradictory results and those needing confirmation. The resulting picture, together with some usually neglected aspects, seems to indicate a link between TERT and TERC functions and cellular stemness and gives possible directions for future research.
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Sui H, Hao M, Chang W, Imamichi T. The Role of Ku70 as a Cytosolic DNA Sensor in Innate Immunity and Beyond. Front Cell Infect Microbiol 2021; 11:761983. [PMID: 34746031 PMCID: PMC8566972 DOI: 10.3389/fcimb.2021.761983] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Accepted: 10/06/2021] [Indexed: 12/24/2022] Open
Abstract
Human Ku70 is a well-known endogenous nuclear protein involved in the non-homologous end joining pathway to repair double-stranded breaks in DNA. However, Ku70 has been studied in multiple contexts and grown into a multifunctional protein. In addition to the extensive functional study of Ku70 in DNA repair process, many studies have emphasized the role of Ku70 in various other cellular processes, including apoptosis, aging, and HIV replication. In this review, we focus on discussing the role of Ku70 in inducing interferons and proinflammatory cytokines as a cytosolic DNA sensor. We explored the unique structure of Ku70 binding with DNA; illustrated, with evidence, how Ku70, as a nuclear protein, responds to extracellular DNA stimulation; and summarized the mechanisms of the Ku70-involved innate immune response pathway. Finally, we discussed several new strategies to modulate Ku70-mediated innate immune response and highlighted some potential physiological insights based on the role of Ku70 in innate immunity.
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Affiliation(s)
- Hongyan Sui
- Laboratory of Human Retrovirology and Immunoinformatics, Frederick National Laboratory for Cancer Research, Frederick, MD, United States
| | | | | | - Tomozumi Imamichi
- Laboratory of Human Retrovirology and Immunoinformatics, Frederick National Laboratory for Cancer Research, Frederick, MD, United States
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8
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Holland CL, Sanderson BA, Titus JK, Weis MF, Riojas AM, Malczewskyj E, Wasko BM, Lewis LK. Suppression of telomere capping defects of Saccharomyces cerevisiae yku70 and yku80 mutants by telomerase. G3-GENES GENOMES GENETICS 2021; 11:6395363. [PMID: 34718547 PMCID: PMC8664480 DOI: 10.1093/g3journal/jkab359] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Accepted: 09/27/2021] [Indexed: 11/18/2022]
Abstract
The Ku complex performs multiple functions inside eukaryotic cells, including protection of chromosomal DNA ends from degradation and fusion events, recruitment of telomerase, and repair of double-strand breaks (DSBs). Inactivation of Ku complex genes YKU70 or YKU80 in cells of the yeast Saccharomyces cerevisiae gives rise to mutants that exhibit shortened telomeres and temperature-sensitive growth. In this study, we have investigated the mechanism by which overexpression of telomerase suppresses the temperature sensitivity of yku mutants. Viability of yku cells was restored by overexpression of the Est2 reverse transcriptase and TLC1 RNA template subunits of telomerase, but not the Est1 or Est3 proteins. Overexpression of other telomerase- and telomere-associated proteins (Cdc13, Stn1, Ten1, Rif1, Rif2, Sir3, and Sir4) did not suppress the growth defects of yku70 cells. Mechanistic features of suppression were assessed using several TLC1 RNA deletion derivatives and Est2 enzyme mutants. Supraphysiological levels of three catalytically inactive reverse transcriptase mutants (Est2-D530A, Est2-D670A, and Est2-D671A) suppressed the loss of viability as efficiently as the wild-type Est2 protein, without inducing cell senescence. Roles of proteins regulating telomere length were also determined. The results support a model in which chromosomes in yku mutants are stabilized via a replication-independent mechanism involving structural reinforcement of protective telomere cap structures.
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Affiliation(s)
- Cory L Holland
- Department of Chemistry and Biochemistry, Texas State University, San Marcos, TX 78666, USA
| | - Brian A Sanderson
- Department of Chemistry and Biochemistry, Texas State University, San Marcos, TX 78666, USA
| | - James K Titus
- Department of Chemistry and Biochemistry, Texas State University, San Marcos, TX 78666, USA
| | - Monica F Weis
- Department of Chemistry and Biochemistry, Texas State University, San Marcos, TX 78666, USA
| | - Angelica M Riojas
- Department of Chemistry and Biochemistry, Texas State University, San Marcos, TX 78666, USA
| | - Eric Malczewskyj
- Department of Chemistry and Biochemistry, Texas State University, San Marcos, TX 78666, USA
| | - Brian M Wasko
- Department of Biology and Biotechnology, University of Houston-Clear Lake, Houston, TX, 77058, USA
| | - L Kevin Lewis
- Department of Chemistry and Biochemistry, Texas State University, San Marcos, TX 78666, USA
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9
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Fekete-Szücs E, Rosas Bringas FR, Stinus S, Chang M. Suppression of cdc13-2-associated senescence by pif1-m2 requires Ku-mediated telomerase recruitment. G3-GENES GENOMES GENETICS 2021; 12:6395364. [PMID: 34751785 PMCID: PMC8728030 DOI: 10.1093/g3journal/jkab360] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Accepted: 10/08/2021] [Indexed: 11/17/2022]
Abstract
In Saccharomyces cerevisiae, recruitment of telomerase to telomeres requires an interaction between Cdc13, which binds single-stranded telomeric DNA, and the Est1 subunit of telomerase. A second pathway involving an interaction between the yKu complex and telomerase RNA (TLC1) contributes to telomerase recruitment but cannot sufficiently recruit telomerase on its own to prevent replicative senescence when the primary Cdc13-Est1 pathway is abolished—for example, in the cdc13-2 mutant. In this study, we find that mutation of PIF1, which encodes a helicase that inhibits telomerase, suppresses the replicative senescence of cdc13-2 by increasing reliance on the yKu-TLC1 pathway for telomerase recruitment. Our findings reveal new insight into telomerase-mediated telomere maintenance.
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Affiliation(s)
- Enikő Fekete-Szücs
- European Research Institute for the Biology of Ageing, University of Groningen, University Medical Center Groningen, Groningen 9713 AV, The Netherlands
| | - Fernando R Rosas Bringas
- European Research Institute for the Biology of Ageing, University of Groningen, University Medical Center Groningen, Groningen 9713 AV, The Netherlands
| | - Sonia Stinus
- European Research Institute for the Biology of Ageing, University of Groningen, University Medical Center Groningen, Groningen 9713 AV, The Netherlands
| | - Michael Chang
- European Research Institute for the Biology of Ageing, University of Groningen, University Medical Center Groningen, Groningen 9713 AV, The Netherlands
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10
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Maturation and shuttling of the yeast telomerase RNP: assembling something new using recycled parts. Curr Genet 2021; 68:3-14. [PMID: 34476547 PMCID: PMC8801399 DOI: 10.1007/s00294-021-01210-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Revised: 08/24/2021] [Accepted: 08/25/2021] [Indexed: 11/10/2022]
Abstract
As the limiting component of the budding yeast telomerase, the Tlc1 RNA must undergo multiple consecutive modifications and rigorous quality checks throughout its lifecycle. These steps will ensure that only correctly processed and matured molecules are assembled into telomerase complexes that subsequently act at telomeres. The complex pathway of Tlc1 RNA maturation, involving 5'- and 3'-end processing, stabilisation and assembly with the protein subunits, requires at least one nucleo-cytoplasmic passage. Furthermore, it appears that the pathway is tightly coordinated with the association of various and changing proteins, including the export factor Xpo1, the Mex67/Mtr2 complex, the Kap122 importin, the Sm7 ring and possibly the CBC and TREX-1 complexes. Although many of these maturation processes also affect other RNA species, the Tlc1 RNA exploits them in a new combination and, therefore, ultimately follows its own and unique pathway. In this review, we highlight recent new insights in maturation and subcellular shuttling of the budding yeast telomerase RNA and discuss how these events may be fine-tuned by the biochemical characteristics of the varying processing and transport factors as well as the final telomerase components. Finally, we indicate outstanding questions that we feel are important to be addressed for a complete understanding of the telomerase RNA lifecycle and that could have implications for the human telomerase as well.
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11
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Abbasi S, Parmar G, Kelly RD, Balasuriya N, Schild-Poulter C. The Ku complex: recent advances and emerging roles outside of non-homologous end-joining. Cell Mol Life Sci 2021; 78:4589-4613. [PMID: 33855626 PMCID: PMC11071882 DOI: 10.1007/s00018-021-03801-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Revised: 01/29/2021] [Accepted: 02/24/2021] [Indexed: 12/15/2022]
Abstract
Since its discovery in 1981, the Ku complex has been extensively studied under multiple cellular contexts, with most work focusing on Ku in terms of its essential role in non-homologous end-joining (NHEJ). In this process, Ku is well-known as the DNA-binding subunit for DNA-PK, which is central to the NHEJ repair process. However, in addition to the extensive study of Ku's role in DNA repair, Ku has also been implicated in various other cellular processes including transcription, the DNA damage response, DNA replication, telomere maintenance, and has since been studied in multiple contexts, growing into a multidisciplinary point of research across various fields. Some advances have been driven by clarification of Ku's structure, including the original Ku crystal structure and the more recent Ku-DNA-PKcs crystallography, cryogenic electron microscopy (cryoEM) studies, and the identification of various post-translational modifications. Here, we focus on the advances made in understanding the Ku heterodimer outside of non-homologous end-joining, and across a variety of model organisms. We explore unique structural and functional aspects, detail Ku expression, conservation, and essentiality in different species, discuss the evidence for its involvement in a diverse range of cellular functions, highlight Ku protein interactions and recent work concerning Ku-binding motifs, and finally, we summarize the clinical Ku-related research to date.
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Affiliation(s)
- Sanna Abbasi
- Robarts Research Institute and Department of Biochemistry, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, N6A 5B7, Canada
| | - Gursimran Parmar
- Robarts Research Institute and Department of Biochemistry, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, N6A 5B7, Canada
| | - Rachel D Kelly
- Robarts Research Institute and Department of Biochemistry, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, N6A 5B7, Canada
| | - Nileeka Balasuriya
- Robarts Research Institute and Department of Biochemistry, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, N6A 5B7, Canada
| | - Caroline Schild-Poulter
- Robarts Research Institute and Department of Biochemistry, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, N6A 5B7, Canada.
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12
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Sir4 Deficiency Reverses Cell Senescence by Sub-Telomere Recombination. Cells 2021; 10:cells10040778. [PMID: 33915984 PMCID: PMC8066019 DOI: 10.3390/cells10040778] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Revised: 03/27/2021] [Accepted: 03/30/2021] [Indexed: 01/14/2023] Open
Abstract
Telomere shortening results in cellular senescence and the regulatory mechanisms remain unclear. Here, we report that the sub-telomere regions facilitate telomere lengthening by homologous recombination, thereby attenuating senescence in yeast Saccharomyces cerevisiae. The telomere protein complex Sir3/4 represses, whereas Rif1 promotes, the sub-telomere Y' element recombination. Genetic disruption of SIR4 increases Y' element abundance and rescues telomere-shortening-induced senescence in a Rad51-dependent manner, indicating a sub-telomere regulatory switch in regulating organismal senescence by DNA recombination. Inhibition of the sub-telomere recombination requires Sir4 binding to perinuclear protein Mps3 for telomere perinuclear localization and transcriptional repression of the telomeric repeat-containing RNA TERRA. Furthermore, Sir4 repression of Y' element recombination is negatively regulated by Rif1 that mediates senescence-evasion induced by Sir4 deficiency. Thus, our results demonstrate a dual opposing control mechanism of sub-telomeric Y' element recombination by Sir3/4 and Rif1 in the regulation of telomere shortening and cell senescence.
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13
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Liu J, Hong X, Liang CY, Liu JP. Simultaneous visualisation of the complete sets of telomeres from the MmeI generated terminal restriction fragments in yeasts. Yeast 2020; 37:585-595. [PMID: 32776370 DOI: 10.1002/yea.3517] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Revised: 08/02/2020] [Accepted: 08/03/2020] [Indexed: 11/07/2022] Open
Abstract
Telomere length is measured using Southern blotting of the chromosomal terminal restriction fragments (TRFs) released by endonuclease digestion in cells from yeast to human. In the budding yeast Saccharomyces cerevisiae, XhoI or PstI is applied to cut the subtelomere Y' element and release TRFs from the 17 subtelomeres. However, telomeres from other 15 X-element-only subtelomeres are omitted from analysis. Here, we report a method for measuring all 32 telomeres in S. cerevisiae using the endonuclease MmeI. Based on analyses of the endonuclease cleavage sites, we found that the TRFs generated by MmeI displayed two distinguishable bands in the sizes of ~500 and ~700 bp comprising telomeres (300 bp) and subtelomeres (200-400 bp). The modified MmeI-restricted TRF (mTRF) method recapitulated telomere shortening and lengthening caused by deficiencies of YKu and Rif1 respectively in S. cerevisiae. Furthermore, we found that mTRF was also applicable to telomere length analysis in S. paradoxus strains. These results demonstrate a useful tool for simultaneous detection of telomeres from all chromosomal ends with both X-element-only and Y'-element subtelomeres in S. cerevisiae species.
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Affiliation(s)
- Jun Liu
- Institute of Ageing Research, College of Medicine, Hangzhou Normal University, Hangzhou, China
| | - Xiaojing Hong
- Institute of Ageing Research, College of Medicine, Hangzhou Normal University, Hangzhou, China
| | - Chao-Ya Liang
- Institute of Ageing Research, College of Medicine, Hangzhou Normal University, Hangzhou, China
| | - Jun-Ping Liu
- Institute of Ageing Research, College of Medicine, Hangzhou Normal University, Hangzhou, China
- Department of Immunology, Faculty of Medicine, Monash University, Prahran, Victoria, Australia
- Hudson Institute of Medical Research, Clayton, Victoria, Australia
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14
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LRIK interacts with the Ku70-Ku80 heterodimer enhancing the efficiency of NHEJ repair. Cell Death Differ 2020; 27:3337-3353. [PMID: 32587379 DOI: 10.1038/s41418-020-0581-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Revised: 06/10/2020] [Accepted: 06/12/2020] [Indexed: 12/15/2022] Open
Abstract
Despite recent advances in our understanding of the function of long noncoding RNAs (lncRNAs), their roles and functions in DNA repair pathways remain poorly understood. By screening a panel of uncharacterized lncRNAs to identify those whose transcription is induced by double-strand breaks (DSBs), we identified a novel lncRNA referred to as LRIK that interacts with Ku, which enhances the ability of the Ku heterodimer to detect the presence of DSBs. Here, we show that depletion of LRIK generates significantly enhanced sensitivity to DSB-inducing agents and reduced DSB repair efficiency. In response to DSBs, LRIK enhances the recruitment of repair factors at DSB sites and facilitates γH2AX signaling. Our results demonstrate that LRIK is necessary for efficient repairing DSBs via nonhomologous end-joining pathway.
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15
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Telomerase Biogenesis and Activities from the Perspective of Its Direct Interacting Partners. Cancers (Basel) 2020; 12:cancers12061679. [PMID: 32599885 PMCID: PMC7352425 DOI: 10.3390/cancers12061679] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Revised: 06/20/2020] [Accepted: 06/22/2020] [Indexed: 12/15/2022] Open
Abstract
Telomerase reverse transcriptase (TERT)—the catalytic subunit of telomerase—is reactivated in up to 90% of all human cancers. TERT is observed in heterogenous populations of protein complexes, which are dynamically regulated in a cell type- and cell cycle-specific manner. Over the past two decades, in vitro protein–protein interaction detection methods have discovered a number of endogenous TERT binding partners in human cells that are responsible for the biogenesis and functionalization of the telomerase holoenzyme, including the processes of TERT trafficking between subcellular compartments, assembly into telomerase, and catalytic action at telomeres. Additionally, TERT have been found to interact with protein species with no known telomeric functions, suggesting that these complexes may contribute to non-canonical activities of TERT. Here, we survey TERT direct binding partners and discuss their contributions to TERT biogenesis and functions. The goal is to review the comprehensive spectrum of TERT pro-malignant activities, both telomeric and non-telomeric, which may explain the prevalence of its upregulation in cancer.
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16
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Shao Z, Flynn RA, Crowe JL, Zhu Y, Liang J, Jiang W, Aryan F, Aoude P, Bertozzi CR, Estes VM, Lee BJ, Bhagat G, Zha S, Calo E. DNA-PKcs has KU-dependent function in rRNA processing and haematopoiesis. Nature 2020; 579:291-296. [PMID: 32103174 PMCID: PMC10919329 DOI: 10.1038/s41586-020-2041-2] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2019] [Accepted: 01/28/2020] [Indexed: 11/09/2022]
Abstract
The DNA-dependent protein kinase (DNA-PK), which comprises the KU heterodimer and a catalytic subunit (DNA-PKcs), is a classical non-homologous end-joining (cNHEJ) factor1. KU binds to DNA ends, initiates cNHEJ, and recruits and activates DNA-PKcs. KU also binds to RNA, but the relevance of this interaction in mammals is unclear. Here we use mouse models to show that DNA-PK has an unexpected role in the biogenesis of ribosomal RNA (rRNA) and in haematopoiesis. The expression of kinase-dead DNA-PKcs abrogates cNHEJ2. However, most mice that both expressed kinase-dead DNA-PKcs and lacked the tumour suppressor TP53 developed myeloid disease, whereas all other previously characterized mice deficient in both cNHEJ and TP53 expression succumbed to pro-B cell lymphoma3. DNA-PK autophosphorylates DNA-PKcs, which is its best characterized substrate. Blocking the phosphorylation of DNA-PKcs at the T2609 cluster, but not the S2056 cluster, led to KU-dependent defects in 18S rRNA processing, compromised global protein synthesis in haematopoietic cells and caused bone marrow failure in mice. KU drives the assembly of DNA-PKcs on a wide range of cellular RNAs, including the U3 small nucleolar RNA, which is essential for processing of 18S rRNA4. U3 activates purified DNA-PK and triggers phosphorylation of DNA-PKcs at T2609. DNA-PK, but not other cNHEJ factors, resides in nucleoli in an rRNA-dependent manner and is co-purified with the small subunit processome. Together our data show that DNA-PK has RNA-dependent, cNHEJ-independent functions during ribosome biogenesis that require the kinase activity of DNA-PKcs and its phosphorylation at the T2609 cluster.
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Affiliation(s)
- Zhengping Shao
- Institute for Cancer Genetics, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, USA
- Herbert Irving Comprehensive Cancer Center, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, USA
| | - Ryan A Flynn
- Department of Chemistry, Stanford University, Stanford, CA, USA
| | - Jennifer L Crowe
- Institute for Cancer Genetics, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, USA
- Graduate Program of Pathobiology and Molecular Medicine, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, USA
| | - Yimeng Zhu
- Institute for Cancer Genetics, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, USA
- Herbert Irving Comprehensive Cancer Center, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, USA
| | - Jialiang Liang
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Wenxia Jiang
- Institute for Cancer Genetics, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, USA
- Herbert Irving Comprehensive Cancer Center, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, USA
| | - Fardin Aryan
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Patrick Aoude
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Carolyn R Bertozzi
- Department of Chemistry, Stanford University, Stanford, CA, USA
- Howard Hughes Medical Institute, Stanford University, Stanford, CA, USA
| | - Verna M Estes
- Institute for Cancer Genetics, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, USA
- Herbert Irving Comprehensive Cancer Center, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, USA
| | - Brian J Lee
- Institute for Cancer Genetics, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, USA
- Herbert Irving Comprehensive Cancer Center, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, USA
| | - Govind Bhagat
- Herbert Irving Comprehensive Cancer Center, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, USA
- Department of Pediatrics, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, USA
- Department of Pathology and Cell Biology, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, USA
- Department of Immunology and Microbiology, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, USA
| | - Shan Zha
- Institute for Cancer Genetics, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, USA.
- Herbert Irving Comprehensive Cancer Center, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, USA.
- Department of Pediatrics, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, USA.
- Department of Pathology and Cell Biology, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, USA.
- Department of Immunology and Microbiology, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, USA.
| | - Eliezer Calo
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA.
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA, USA.
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17
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Shadrina O, Garanina I, Korolev S, Zatsepin T, Van Assche J, Daouad F, Wallet C, Rohr O, Gottikh M. Analysis of RNA binding properties of human Ku protein reveals its interactions with 7SK snRNA and protein components of 7SK snRNP complex. Biochimie 2020; 171-172:110-123. [PMID: 32105815 DOI: 10.1016/j.biochi.2020.02.016] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Accepted: 02/21/2020] [Indexed: 12/21/2022]
Abstract
Human Ku heterodimeric protein composed of Ku70 and Ku80 subunits plays an important role in the non-homologous end-joining DNA repair pathway as a sensor of double strand DNA breaks. Ku is also involved in numerous cellular processes, and in some of them it acts in an RNA-dependent manner. However, RNA binding properties of the human Ku have not been well studied. Here we have analyzed interactions of a recombinant Ku heterodimer with a set of RNAs of various structure as well as eCLIP (enhanced crosslinking and immunoprecipitation) data for human Ku70. As a result, we have proposed a consensus RNA structure preferable for the Ku binding that is a hairpin possessing a bulge just near GpG sequence-containing terminal loop. 7SK snRNA is a scaffold for a ribonucleoprotein complex (7SK snRNP), which is known to participate in transcription regulation. We have shown that the recombinant Ku specifically binds a G-rich loop of hairpin 1 within 7SK snRNA. Moreover, Ku protein has been co-precipitated from HEK 293T cells with endogenous 7SK snRNA and such proteins included in 7SK snRNP as HEXIM1, Cdk9 and CTIP2. Ku and Cdk9 binding is found to be RNA-independent, meanwhile HEXIM1 and Ku co-precipitation depended on the presence of intact 7SK snRNA. The latter result has been confirmed using recombinant HEXIM1 and Ku proteins. Colocalization of Ku and CTIP2 was additionally confirmed by confocal microscopy. These results allow us to propose human Ku as a new component of the 7SK snRNP complex.
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Affiliation(s)
- Olga Shadrina
- Chemistry Department, Lomonosov Moscow State University, Moscow, 199991, Russia; Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 119992, Moscow, Russia.
| | - Irina Garanina
- Federal Research and Clinical Center of Physical-Chemical Medicine of Federal Medical Biological Agency, Moscow, 119435, Russia
| | - Sergey Korolev
- Chemistry Department, Lomonosov Moscow State University, Moscow, 199991, Russia; Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 119992, Moscow, Russia
| | - Timofei Zatsepin
- Chemistry Department, Lomonosov Moscow State University, Moscow, 199991, Russia; Skolkovo Institute of Science and Technology, Skolkovo, 121205, Russia
| | - Jeanne Van Assche
- Université de Strasbourg, EA7292, FMTS, IUT Louis Pasteur, Schiltigheim, France
| | - Fadoua Daouad
- Université de Strasbourg, EA7292, FMTS, IUT Louis Pasteur, Schiltigheim, France
| | - Clementine Wallet
- Université de Strasbourg, EA7292, FMTS, IUT Louis Pasteur, Schiltigheim, France
| | - Olivier Rohr
- Université de Strasbourg, EA7292, FMTS, IUT Louis Pasteur, Schiltigheim, France
| | - Marina Gottikh
- Chemistry Department, Lomonosov Moscow State University, Moscow, 199991, Russia; Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 119992, Moscow, Russia
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18
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Lalonde M, Chartrand P. TERRA, a Multifaceted Regulator of Telomerase Activity at Telomeres. J Mol Biol 2020; 432:4232-4243. [PMID: 32084415 DOI: 10.1016/j.jmb.2020.02.004] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Revised: 02/06/2020] [Accepted: 02/10/2020] [Indexed: 02/07/2023]
Abstract
In eukaryotes, telomeres are repetitive sequences at the end of chromosomes, which are maintained in a constitutive heterochromatin state. It is now known that telomeres can be actively transcribed, leading to the production of a telomeric repeat-containing noncoding RNA called TERRA. Due to its sequence complementarity to the telomerase template, it was suggested early on that TERRA could be an inhibitor of telomerase. Since then, TERRA has been shown to be involved in heterochromatin formation at telomeres, to invade telomeric dsDNA and form R-loops, and even to promote telomerase recruitment at short telomeres. All these functions depend on the diverse capacities of this lncRNA to bind various cofactors, act as a scaffold, and promote higher-order complexes in cells. In this review, it will be highlighted as to how these properties of TERRA work together to regulate telomerase activity at telomeres.
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Affiliation(s)
- Maxime Lalonde
- Department of Biochemistry and Molecular Medicine, Université de Montréal, Quebec, Canada
| | - Pascal Chartrand
- Department of Biochemistry and Molecular Medicine, Université de Montréal, Quebec, Canada.
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19
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Sui J, Zhang S, Chen BPC. DNA-dependent protein kinase in telomere maintenance and protection. Cell Mol Biol Lett 2020; 25:2. [PMID: 31988640 PMCID: PMC6969447 DOI: 10.1186/s11658-020-0199-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Accepted: 01/02/2020] [Indexed: 12/12/2022] Open
Abstract
This review focuses on DNA-dependent protein kinase (DNA-PK), which is the key regulator of canonical non-homologous end-joining (NHEJ), the predominant mechanism of DNA double-strand break (DSB) repair in mammals. DNA-PK consists of the DNA-binding Ku70/80 heterodimer and the catalytic subunit DNA-PKcs. They assemble at DNA ends, forming the active DNA-PK complex, which initiates NHEJ-mediated DSB repair. Paradoxically, both Ku and DNA-PKcs are associated with telomeres, and they play crucial roles in protecting the telomere against fusions. Herein, we discuss possible mechanisms and contributions of Ku and DNA-PKcs in telomere regulation.
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Affiliation(s)
- Jiangdong Sui
- 1Radiation Oncology Center, Chongqing University Cancer Hospital, Chongqing, 400030 China
| | - Shichuan Zhang
- 2Department of Radiation Oncology, Sichuan Cancer Hospital, Chengdu, China
| | - Benjamin P C Chen
- 3Department of Radiation Oncology, University of Texas Southwestern Medical Center, 2201 Inwood Rd., Dallas, TX 75390-9187 USA
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20
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lncRNA CISAL Inhibits BRCA1 Transcription by Forming a Tertiary Structure at Its Promoter. iScience 2020; 23:100835. [PMID: 32000125 PMCID: PMC7033639 DOI: 10.1016/j.isci.2020.100835] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2019] [Revised: 11/25/2019] [Accepted: 01/08/2020] [Indexed: 11/21/2022] Open
Abstract
Cisplatin-based neoadjuvant chemotherapy has been shown to improve survival in patients with squamous cell carcinoma (SCC), but clinical biomarkers to predict chemosensitivity remain elusive. Here, we show the long noncoding RNA (lncRNA) LINC01011, which we termed cisplatin-sensitivity-associated lncRNA (CISAL), controls mitochondrial fission and cisplatin sensitivity by inhibiting BRCA1 transcription in tongue SCC (TSCC) models. Mechanistically, we found CISAL directly binds the BRCA1 promoter and forms an RNA-DNA triplex structure, sequestering BRCA1 transcription factor-GABPA away from the downstream regulatory binding region. Importantly, the clinical relevance of these findings is suggested by the significant association of CISAL and BRCA1 expression levels in TSCC tumors with neoadjuvant chemosensitivity and overall survival. We propose a new model where lncRNAs are tethered at gene promoter by RNA-DNA triplex formation, spatially sequestering transcription factors away from DNA-binding sites. Our study uncovers the potential of CISAL-BRCA1 signaling as a potential target to predict or improve chemosensitivity. CISAL enhances mitochondrial fission and cisplatin sensitivity in TSCC cells through BRCA1 CISAL directly binds the BRCA1 promoter and forms an RNA-DNA triplex structure CISAL sequesters GABPA away from regulatory binding at BRCA1 promoter High CISAL predicts favorable neoadjuvant chemosensitivity and prognosis of TSCC patients
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21
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He MH, Liu JC, Lu YS, Wu ZJ, Liu YY, Wu Z, Peng J, Zhou JQ. KEOPS complex promotes homologous recombination via DNA resection. Nucleic Acids Res 2019; 47:5684-5697. [PMID: 30937455 PMCID: PMC6582355 DOI: 10.1093/nar/gkz228] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2018] [Revised: 03/19/2019] [Accepted: 03/29/2019] [Indexed: 12/01/2022] Open
Abstract
KEOPS complex is one of the most conserved protein complexes in eukaryotes. It plays important roles in both telomere uncapping and tRNA N6-threonylcarbamoyladenosine (t6A) modification in budding yeast. But whether KEOPS complex plays any roles in DNA repair remains unknown. Here, we show that KEOPS complex plays positive roles in both DNA damage response and homologous recombination-mediated DNA repair independently of its t6A synthesis function. Additionally, KEOPS displays DNA binding activity in vitro, and is recruited to the chromatin at DNA breaks in vivo, suggesting a direct role of KEOPS in DSB repair. Mechanistically, KEOPS complex appears to promote DNA end resection through facilitating the association of Exo1 and Dna2 with DNA breaks. Interestingly, inactivation of both KEOPS and Mre11/Rad50/Xrs2 (MRX) complexes results in synergistic defect in DNA resection, revealing that KEOPS and MRX have some redundant functions in DNA resection. Thus we uncover a t6A-independent role of KEOPS complex in DNA resection, and propose that KEOPS might be a DSB sensor to assist cells in maintaining chromosome stability.
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Affiliation(s)
- Ming-Hong He
- The State Key Laboratory of Molecular Biology, 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, 320 Yueyang Road, Shanghai 200031, China
| | - Jia-Cheng Liu
- The State Key Laboratory of Molecular Biology, 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, 320 Yueyang Road, Shanghai 200031, China
| | - Yi-Si Lu
- The State Key Laboratory of Molecular Biology, 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, 320 Yueyang Road, Shanghai 200031, China
| | - Zhi-Jing Wu
- The State Key Laboratory of Molecular Biology, 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, 320 Yueyang Road, Shanghai 200031, China
| | - Ying-Ying Liu
- The State Key Laboratory of Molecular Biology, 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, 320 Yueyang Road, Shanghai 200031, China.,School of Life Science and Technology, Shanghai Tech University, 100 Haike Road, Shanghai 201201, China
| | - Zhenfang Wu
- The State Key Laboratory of Molecular Biology, 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, 320 Yueyang Road, Shanghai 200031, China
| | - Jing Peng
- The State Key Laboratory of Molecular Biology, 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, 320 Yueyang Road, Shanghai 200031, China
| | - Jin-Qiu Zhou
- The State Key Laboratory of Molecular Biology, 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, 320 Yueyang Road, Shanghai 200031, China.,School of Life Science and Technology, Shanghai Tech University, 100 Haike Road, Shanghai 201201, China
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22
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Liu B, Maekawa T, Yoshida K, Ly NH, Inoue K, Hasegawa A, Chatton B, Ogura A, Ishii S. Telomere shortening by transgenerational transmission of TNF-α-induced TERRA via ATF7. Nucleic Acids Res 2019; 47:283-298. [PMID: 30407559 PMCID: PMC6326783 DOI: 10.1093/nar/gky1149] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Accepted: 10/30/2018] [Indexed: 12/30/2022] Open
Abstract
Various stresses increase disease susceptibility and accelerate aging, and increasing evidence suggests that these effects can be transmitted over generation. Epidemiological studies suggest that stressors experienced by parents affect the longevity of their offspring, possibly by regulating telomere dynamics. Telomeres are elongated by telomerase and shortened by certain stresses as well as telomere repeat-containing RNA (TERRA), a telomere transcript. However, the mechanism underlying the transgenerational effects is poorly understood. Here, we show that TNF-α, which is induced by various psychological stresses, induces the p38-dependent phosphorylation of ATF7, a stress-responsive chromatin regulator, in mouse testicular germ cells. This caused a release of ATF7 from the TERRA gene promoter in the subtelomeric region, which disrupted heterochromatin and induced TERRA. TERRA was transgenerationally transmitted to zygotes via sperm and caused telomere shortening. These results suggest that ATF7 and TERRA play key roles in paternal stress-induced telomere shortening in the offspring.
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Affiliation(s)
- Binbin Liu
- RIKEN Cluster for Pioneering Research, Tsukuba, Ibaraki 305-0074, Japan
| | - Toshio Maekawa
- RIKEN Cluster for Pioneering Research, Tsukuba, Ibaraki 305-0074, Japan
| | - Keisuke Yoshida
- RIKEN Cluster for Pioneering Research, Tsukuba, Ibaraki 305-0074, Japan
| | - Nhung Hong Ly
- RIKEN Cluster for Pioneering Research, Tsukuba, Ibaraki 305-0074, Japan.,Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8577, Japan
| | - Kimiko Inoue
- RIKEN BioResource Center, Tsukuba, Ibaraki 305-0074, Japan
| | - Ayumi Hasegawa
- RIKEN BioResource Center, Tsukuba, Ibaraki 305-0074, Japan
| | - Bruno Chatton
- Université de Strasbourg, UMR7242 Biotechnologie et Signalisation Cellulaire, Ecole Supérieure de Biotechnologie de Strasbourg, BP10413, Illkirch, France
| | - Atsuo Ogura
- RIKEN BioResource Center, Tsukuba, Ibaraki 305-0074, Japan
| | - Shunsuke Ishii
- RIKEN Cluster for Pioneering Research, Tsukuba, Ibaraki 305-0074, Japan.,Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8577, Japan
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23
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Lemon LD, Morris DK, Bertuch AA. Loss of Ku's DNA end binding activity affects telomere length via destabilizing telomere-bound Est1 rather than altering TLC1 homeostasis. Sci Rep 2019; 9:10607. [PMID: 31337791 PMCID: PMC6650470 DOI: 10.1038/s41598-019-46840-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Accepted: 07/05/2019] [Indexed: 11/21/2022] Open
Abstract
Saccharomyces cerevisiae telomerase, which maintains telomere length, is comprised of an RNA component, TLC1, the reverse transcriptase, Est2, and regulatory subunits, including Est1. The Yku70/Yku80 (Ku) heterodimer, a DNA end binding (DEB) protein, also contributes to telomere length maintenance. Ku binds TLC1 and telomere ends in a mutually exclusive fashion, and is required to maintain levels and nuclear localization of TLC1. Ku also interacts with Sir4, which localizes to telomeres. Here we sought to determine the role of Ku's DEB activity in telomere length maintenance by utilizing yku70-R456E mutant strains, in which Ku has reduced DEB and telomere association but proficiency in TLC1 and Sir4 binding, and TLC1 nuclear retention. Telomere lengths in a yku70-R456E strain were nearly as short as those in yku∆ strains and shorter than in strains lacking either Sir4, Ku:Sir4 interaction, or Ku:TLC1 interaction. TLC1 levels were decreased in the yku70-R456E mutant, yet overexpression of TLC1 failed to restore telomere length. Reduced DEB activity did not impact Est1's ability to associate with telomerase but did result in decreased association of Est1 with the telomere. These findings suggest Ku's DEB activity maintains telomere length homeostasis by preserving Est1's interaction at the telomere rather than altering TLC1 levels.
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Affiliation(s)
- Laramie D Lemon
- Graduate Program in Integrative Molecular and Biomedical Sciences, Baylor College of Medicine, Houston, TX, 77030, USA
- Department of Pediatrics, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Danna K Morris
- Department of Pediatrics, Baylor College of Medicine, Houston, TX, 77030, USA
| | - Alison A Bertuch
- Graduate Program in Integrative Molecular and Biomedical Sciences, Baylor College of Medicine, Houston, TX, 77030, USA.
- Department of Pediatrics, Baylor College of Medicine, Houston, TX, 77030, USA.
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24
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Maekawa T, Liu B, Nakai D, Yoshida K, Nakamura KI, Yasukawa M, Koike M, Takubo K, Chatton B, Ishikawa F, Masutomi K, Ishii S. ATF7 mediates TNF-α-induced telomere shortening. Nucleic Acids Res 2019; 46:4487-4504. [PMID: 29490055 PMCID: PMC5961373 DOI: 10.1093/nar/gky155] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Accepted: 02/20/2018] [Indexed: 12/23/2022] Open
Abstract
Telomeres maintain the integrity of chromosome ends and telomere length is an important marker of aging. The epidemiological studies suggested that many types of stress including psychosocial stress decrease telomere length. However, it remains unknown how various stresses induce telomere shortening. Here, we report that the stress-responsive transcription factor ATF7 mediates TNF-α–induced telomere shortening. ATF7 and telomerase, an enzyme that elongates telomeres, are localized on telomeres via interactions with the Ku complex. In response to TNF-α, which is induced by various stresses including psychological stress, ATF7 was phosphorylated by p38, leading to the release of ATF7 and telomerase from telomeres. Thus, a decrease of ATF7 and telomerase on telomeres in response to stress causes telomere shortening, as observed in ATF7-deficient mice. These findings give credence to the idea that various types of stress might shorten telomere.
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Affiliation(s)
- Toshio Maekawa
- Laboratory of Molecular Genetics, RIKEN Tsukuba Institute, 3-1-1 Koyadai, Tsukuba, Ibaraki 305-0074, Japan
| | - Binbin Liu
- Laboratory of Molecular Genetics, RIKEN Tsukuba Institute, 3-1-1 Koyadai, Tsukuba, Ibaraki 305-0074, Japan.,Graduate School of Comprehensive Human Sciences, University of Tsukuba, 1-1-1 Tennoudai, Tsukuba, Ibaraki 305-8577, Japan
| | - Daisuke Nakai
- Laboratory of Molecular Genetics, RIKEN Tsukuba Institute, 3-1-1 Koyadai, Tsukuba, Ibaraki 305-0074, Japan.,Graduate School of Comprehensive Human Sciences, University of Tsukuba, 1-1-1 Tennoudai, Tsukuba, Ibaraki 305-8577, Japan
| | - Keisuke Yoshida
- Laboratory of Molecular Genetics, RIKEN Tsukuba Institute, 3-1-1 Koyadai, Tsukuba, Ibaraki 305-0074, Japan
| | - Ken-Ichi Nakamura
- Research Team for Geriatric Diseases, Tokyo Metropolitan Institute of Gerontology, Sakaecho 35-2, Itabashi-ku, Tokyo 173-0015, Japan
| | - Mami Yasukawa
- Division of Cancer Stem Cell, National Cancer Center Research Institute, Tokyo, Japan
| | - Manabu Koike
- National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, Japan
| | - Kaiyo Takubo
- Research Team for Geriatric Diseases, Tokyo Metropolitan Institute of Gerontology, Sakaecho 35-2, Itabashi-ku, Tokyo 173-0015, Japan
| | - Bruno Chatton
- Université de Strasbourg, UMR7242 Biotechnologie et Signalisation Cellulaire, Ecole Supérieure de Biotechnologie de Strasbourg, BP10413, Illkirch, France
| | - Fuyuki Ishikawa
- Department of Gene Mechanisms, Graduate School of Biostudies, Kyoto University, Yoshida-Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan
| | - Kenkichi Masutomi
- Division of Cancer Stem Cell, National Cancer Center Research Institute, Tokyo, Japan
| | - Shunsuke Ishii
- Laboratory of Molecular Genetics, RIKEN Tsukuba Institute, 3-1-1 Koyadai, Tsukuba, Ibaraki 305-0074, Japan.,Graduate School of Comprehensive Human Sciences, University of Tsukuba, 1-1-1 Tennoudai, Tsukuba, Ibaraki 305-8577, Japan
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25
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Liu J, Wang L, Wang Z, Liu JP. Roles of Telomere Biology in Cell Senescence, Replicative and Chronological Ageing. Cells 2019; 8:E54. [PMID: 30650660 PMCID: PMC6356700 DOI: 10.3390/cells8010054] [Citation(s) in RCA: 93] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2018] [Revised: 01/08/2019] [Accepted: 01/09/2019] [Indexed: 01/07/2023] Open
Abstract
Telomeres with G-rich repetitive DNA and particular proteins as special heterochromatin structures at the termini of eukaryotic chromosomes are tightly maintained to safeguard genetic integrity and functionality. Telomerase as a specialized reverse transcriptase uses its intrinsic RNA template to lengthen telomeric G-rich strand in yeast and human cells. Cells sense telomere length shortening and respond with cell cycle arrest at a certain size of telomeres referring to the "Hayflick limit." In addition to regulating the cell replicative senescence, telomere biology plays a fundamental role in regulating the chronological post-mitotic cell ageing. In this review, we summarize the current understandings of telomere regulation of cell replicative and chronological ageing in the pioneer model system Saccharomyces cerevisiae and provide an overview on telomere regulation of animal lifespans. We focus on the mechanisms of survivals by telomere elongation, DNA damage response and environmental factors in the absence of telomerase maintenance of telomeres in the yeast and mammals.
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Affiliation(s)
- Jun Liu
- Institute of Ageing Research, School of Medicine, Hangzhou Normal University, Hangzhou 311121, Zhejiang, China.
| | - Lihui Wang
- Institute of Ageing Research, School of Medicine, Hangzhou Normal University, Hangzhou 311121, Zhejiang, China.
| | - Zhiguo Wang
- Institute of Ageing Research, School of Medicine, Hangzhou Normal University, Hangzhou 311121, Zhejiang, China.
| | - Jun-Ping Liu
- Institute of Ageing Research, School of Medicine, Hangzhou Normal University, Hangzhou 311121, Zhejiang, China.
- Department of Immunology, Monash University Faculty of Medicine, Melbourne, Vitoria 3004, Australia.
- Hudson Institute of Medical Research, Clayton, Victoria 3168, Australia.
- Department of Molecular and Translational Science, Monash University, Clayton, Victoria 3168, Australia.
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26
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Piñeiro D, Stoneley M, Ramakrishna M, Alexandrova J, Dezi V, Juke-Jones R, Lilley KS, Cain K, Willis AE. Identification of the RNA polymerase I-RNA interactome. Nucleic Acids Res 2018; 46:11002-11013. [PMID: 30169671 PMCID: PMC6237751 DOI: 10.1093/nar/gky779] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Revised: 07/27/2018] [Accepted: 08/29/2018] [Indexed: 12/13/2022] Open
Abstract
Ribosome biogenesis is a complex process orchestrated by a host of ribosome assembly factors. Although it is known that many of the proteins involved in this process have RNA binding activity, the full repertoire of proteins that interact with the precursor ribosomal RNA is currently unknown. To gain a greater understanding of the extent to which RNA-protein interactions have the potential to control ribosome biogenesis, we used RNA affinity isolation coupled with proteomics to measure the changes in RNA-protein interactions that occur when rRNA transcription is blocked. Our analysis identified 211 out of 457 nuclear RNA binding proteins with a >3-fold decrease in RNA-protein interaction after inhibition of RNA polymerase I (RNAPI). We have designated these 211 RNA binding proteins as the RNAPI RNA interactome. As expected, the RNAPI RNA interactome is highly enriched for nucleolar proteins and proteins associated with ribosome biogenesis. Selected proteins from the interactome were shown to be nucleolar in location and to have RNA binding activity that was dependent on RNAPI activity. Furthermore, our data show that two proteins, which are required for rRNA maturation, AATF and NGDN, and which form part of the RNA interactome, both lack canonical RNA binding domains and yet are novel pre-rRNA binding proteins.
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Affiliation(s)
- David Piñeiro
- Medical Research Council Toxicology Unit, University of Cambridge, Lancaster Rd, Leicester LE1 9HN, UK
| | - Mark Stoneley
- Medical Research Council Toxicology Unit, University of Cambridge, Lancaster Rd, Leicester LE1 9HN, UK
| | - Manasa Ramakrishna
- Medical Research Council Toxicology Unit, University of Cambridge, Lancaster Rd, Leicester LE1 9HN, UK
| | - Jana Alexandrova
- Medical Research Council Toxicology Unit, University of Cambridge, Lancaster Rd, Leicester LE1 9HN, UK
| | - Veronica Dezi
- Medical Research Council Toxicology Unit, University of Cambridge, Lancaster Rd, Leicester LE1 9HN, UK
| | - Rebekha Juke-Jones
- Medical Research Council Toxicology Unit, University of Cambridge, Lancaster Rd, Leicester LE1 9HN, UK
| | - Kathryn S Lilley
- Cambridge Centre for Proteomics, University of Cambridge, Department of Biochemistry, Tennis Court Road, Cambridge CB2 1QR, UK
| | - Kelvin Cain
- Medical Research Council Toxicology Unit, University of Cambridge, Lancaster Rd, Leicester LE1 9HN, UK
| | - Anne E Willis
- Medical Research Council Toxicology Unit, University of Cambridge, Lancaster Rd, Leicester LE1 9HN, UK
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27
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Ku DNA End-Binding Activity Promotes Repair Fidelity and Influences End-Processing During Nonhomologous End-Joining in Saccharomyces cerevisiae. Genetics 2018; 209:115-128. [PMID: 29500182 DOI: 10.1534/genetics.117.300672] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2017] [Accepted: 02/25/2018] [Indexed: 12/21/2022] Open
Abstract
The Ku heterodimer acts centrally in nonhomologous end-joining (NHEJ) of DNA double-strand breaks (DSB). Saccharomyces cerevisiae Ku, like mammalian Ku, binds and recruits NHEJ factors to DSB ends. Consequently, NHEJ is virtually absent in yeast Ku null (yku70∆ or yku80∆) strains. Previously, we unexpectedly observed imprecise NHEJ proficiency in a yeast Ku mutant with impaired DNA end-binding (DEB). However, how DEB impairment supported imprecise NHEJ was unknown. Here, we found imprecise NHEJ proficiency to be a feature of a panel of DEB-impaired Ku mutants and that DEB impairment resulted in a deficiency in precise NHEJ. These results suggest that DEB-impaired Ku specifically promotes error-prone NHEJ. Epistasis analysis showed that classical NHEJ factors, as well as novel and previously characterized NHEJ-specific residues of Ku, are required for the distinct error-prone repair in a Ku DEB mutant. However, sequencing of repair junctions revealed that imprecise repair in Ku DEB mutants was almost exclusively characterized by small deletions, in contrast to the majority of insertions that define imprecise repair in wild-type strains. Notably, while sequencing indicated a lack of Pol4-dependent insertions at the site of repair, Pol2 exonuclease activity, which mediates small deletions in NHEJ, contributed to imprecise NHEJ in a Ku DEB mutant. The deletions were smaller than in Ku-independent microhomology-mediated end-joining (MMEJ) and were neither promoted by Mre11 nuclease activity nor Sae2 Thus, the quality of Ku's engagement at the DNA end influences end-processing during NHEJ and DEB impairment unmasks a Ku-dependent error-prone pathway of end-joining distinct from MMEJ.
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Current Perspectives of Telomerase Structure and Function in Eukaryotes with Emerging Views on Telomerase in Human Parasites. Int J Mol Sci 2018; 19:ijms19020333. [PMID: 29364142 PMCID: PMC5855555 DOI: 10.3390/ijms19020333] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Revised: 01/10/2018] [Accepted: 01/17/2018] [Indexed: 12/11/2022] Open
Abstract
Replicative capacity of a cell is strongly correlated with telomere length regulation. Aberrant lengthening or reduction in the length of telomeres can lead to health anomalies, such as cancer or premature aging. Telomerase is a master regulator for maintaining replicative potential in most eukaryotic cells. It does so by controlling telomere length at chromosome ends. Akin to cancer cells, most single-cell eukaryotic pathogens are highly proliferative and require persistent telomerase activity to maintain constant length of telomere and propagation within their host. Although telomerase is key to unlimited cellular proliferation in both cases, not much was known about the role of telomerase in human parasites (malaria, Trypanosoma, etc.) until recently. Since telomerase regulation is mediated via its own structural components, interactions with catalytic reverse transcriptase and several factors that can recruit and assemble telomerase to telomeres in a cell cycle-dependent manner, we compare and discuss here recent findings in telomerase biology in cancer, aging and parasitic diseases to give a broader perspective of telomerase function in human diseases.
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29
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Cdc73 suppresses genome instability by mediating telomere homeostasis. PLoS Genet 2018; 14:e1007170. [PMID: 29320491 PMCID: PMC5779705 DOI: 10.1371/journal.pgen.1007170] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Revised: 01/23/2018] [Accepted: 12/25/2017] [Indexed: 12/18/2022] Open
Abstract
Defects in the genes encoding the Paf1 complex can cause increased genome instability. Loss of Paf1, Cdc73, and Ctr9, but not Rtf1 or Leo1, caused increased accumulation of gross chromosomal rearrangements (GCRs). Combining the cdc73Δ mutation with individual deletions of 43 other genes, including TEL1 and YKU80, which are involved in telomere maintenance, resulted in synergistic increases in GCR rates. Whole genome sequence analysis of GCRs indicated that there were reduced relative rates of GCRs mediated by de novo telomere additions and increased rates of translocations and inverted duplications in cdc73Δ single and double mutants. Analysis of telomere lengths and telomeric gene silencing in strains containing different combinations of cdc73Δ, tel1Δ and yku80Δ mutations suggested that combinations of these mutations caused increased defects in telomere maintenance. A deletion analysis of Cdc73 revealed that a central 105 amino acid region was necessary and sufficient for suppressing the defects observed in cdc73Δ strains; this region was required for the binding of Cdc73 to the Paf1 complex through Ctr9 and for nuclear localization of Cdc73. Taken together, these data suggest that the increased GCR rate of cdc73Δ single and double mutants is due to partial telomere dysfunction and that Ctr9 and Paf1 play a central role in the Paf1 complex potentially by scaffolding the Paf1 complex subunits or by mediating recruitment of the Paf1 complex to the different processes it functions in. Maintaining a stable genome is crucial for all organisms, and loss of genome stability has been linked to multiple human diseases, including many cancers. Previously we found that defects in Cdc73, a component of the Paf1 transcriptional elongation complex, give rise to increased genome instability. Here, we explored the mechanism underlying this instability and found that Cdc73 defects give rise to partial defects in maintaining telomeres, which are the specialized ends of chromosomes, and interact with other mutations causing telomere defects. Remarkably, Cdc73 function is mediated through a short central region of the protein that is not a part of previously identified protein domains but targets Cdc73 to the Paf1 complex through interaction with the Ctr9 subunit. Analysis of the other components of the Paf1 complex provides a model in which the Paf1 subunit mediates recruitment of the other subunits to different processes they function in. Together, these data suggest that the mutations in CDC73 and CTR9 found in patients with hyperparathyroidism-jaw tumor syndrome and some patients with Wilms tumors, respectively, may contribute to cancer progression by contributing to genome instability.
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30
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Chen H, Xue J, Churikov D, Hass EP, Shi S, Lemon LD, Luciano P, Bertuch AA, Zappulla DC, Géli V, Wu J, Lei M. Structural Insights into Yeast Telomerase Recruitment to Telomeres. Cell 2017; 172:331-343.e13. [PMID: 29290466 DOI: 10.1016/j.cell.2017.12.008] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Revised: 09/27/2017] [Accepted: 12/04/2017] [Indexed: 10/18/2022]
Abstract
Telomerase maintains chromosome ends from humans to yeasts. Recruitment of yeast telomerase to telomeres occurs through its Ku and Est1 subunits via independent interactions with telomerase RNA (TLC1) and telomeric proteins Sir4 and Cdc13, respectively. However, the structures of the molecules comprising these telomerase-recruiting pathways remain unknown. Here, we report crystal structures of the Ku heterodimer and Est1 complexed with their key binding partners. Two major findings are as follows: (1) Ku specifically binds to telomerase RNA in a distinct, yet related, manner to how it binds DNA; and (2) Est1 employs two separate pockets to bind distinct motifs of Cdc13. The N-terminal Cdc13-binding site of Est1 cooperates with the TLC1-Ku-Sir4 pathway for telomerase recruitment, whereas the C-terminal interface is dispensable for binding Est1 in vitro yet is nevertheless essential for telomere maintenance in vivo. Overall, our results integrate previous models and provide fundamentally valuable structural information regarding telomere biology.
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Affiliation(s)
- Hongwen Chen
- State Key Laboratory of Molecular Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 201210 Shanghai, China
| | - Jing Xue
- State Key Laboratory of Molecular Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 201210 Shanghai, China
| | - Dmitri Churikov
- Marseille Cancer Research Center (CRCM), U1068 INSERM, UMR7258 CNRS, Aix Marseille University, Institut Paoli-Calmettes (Equipe labellisée Ligue), 13009 Marseille, France
| | - Evan P Hass
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Shaohua Shi
- State Key Laboratory of Molecular Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 201210 Shanghai, China
| | - Laramie D Lemon
- Department of Pediatrics, Baylor College of Medicine, One Baylor Plaza, BCM225, Houston, TX 77030, USA
| | - Pierre Luciano
- Marseille Cancer Research Center (CRCM), U1068 INSERM, UMR7258 CNRS, Aix Marseille University, Institut Paoli-Calmettes (Equipe labellisée Ligue), 13009 Marseille, France
| | - Alison A Bertuch
- Department of Pediatrics, Baylor College of Medicine, One Baylor Plaza, BCM225, Houston, TX 77030, USA
| | - David C Zappulla
- Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA
| | - Vincent Géli
- Marseille Cancer Research Center (CRCM), U1068 INSERM, UMR7258 CNRS, Aix Marseille University, Institut Paoli-Calmettes (Equipe labellisée Ligue), 13009 Marseille, France
| | - Jian Wu
- State Key Laboratory of Molecular Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 201210 Shanghai, China.
| | - Ming Lei
- Shanghai Institute of Precision Medicine, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200125, China; Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Shanghai Jiao Tong University School of Medicine, 200025 Shanghai, China.
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31
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Telomerase RNA Imaging in Budding Yeast and Human Cells by Fluorescent In Situ Hybridization. Methods Mol Biol 2017. [PMID: 29043638 DOI: 10.1007/978-1-4939-7306-4_27] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
Telomerase, the enzyme that elongates telomeres in most eukaryotes, is a ribonucleoprotein complex composed of a reverse transcriptase catalytic subunit (TERT in human, Est2 in the budding yeast S. cerevisiae), regulatory factors and a noncoding RNA called hTERC (in human) or TLC1 (in budding yeast). Telomerase trafficking is a major process in the biogenesis and regulation of telomerase action at telomeres. Due to its higher signal-to-noise ratio, imaging of the telomerase RNA moiety is frequently used to determine telomerase intracellular localization. Here we describe how to image telomerase RNA in human and yeast cells using fluorescence in situ hybridization.
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32
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Long Y, Wang X, Youmans DT, Cech TR. How do lncRNAs regulate transcription? SCIENCE ADVANCES 2017; 3:eaao2110. [PMID: 28959731 PMCID: PMC5617379 DOI: 10.1126/sciadv.aao2110] [Citation(s) in RCA: 454] [Impact Index Per Article: 64.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2017] [Accepted: 09/12/2017] [Indexed: 05/11/2023]
Abstract
It has recently become apparent that RNA, itself the product of transcription, is a major regulator of the transcriptional process. In particular, long noncoding RNAs (lncRNAs), which are so numerous in eukaryotes, function in many cases as transcriptional regulators. These RNAs function through binding to histone-modifying complexes, to DNA binding proteins (including transcription factors), and even to RNA polymerase II. In other cases, it is the act of lncRNA transcription rather than the lncRNA product that appears to be regulatory. We review recent progress in elucidating the molecular mechanisms by which lncRNAs modulate gene expression and future opportunities in this research field.
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Affiliation(s)
- Yicheng Long
- Department of Chemistry and Biochemistry, University of Colorado BioFrontiers Institute, and Howard Hughes Medical Institute, University of Colorado, Boulder, CO 80309, USA
| | - Xueyin Wang
- Department of Chemistry and Biochemistry, University of Colorado BioFrontiers Institute, and Howard Hughes Medical Institute, University of Colorado, Boulder, CO 80309, USA
| | - Daniel T. Youmans
- Department of Chemistry and Biochemistry, University of Colorado BioFrontiers Institute, and Howard Hughes Medical Institute, University of Colorado, Boulder, CO 80309, USA
- Anschutz Medical Campus, University of Colorado Denver, Aurora, CO 80045, USA
| | - Thomas R. Cech
- Department of Chemistry and Biochemistry, University of Colorado BioFrontiers Institute, and Howard Hughes Medical Institute, University of Colorado, Boulder, CO 80309, USA
- Corresponding author.
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Ouenzar F, Lalonde M, Laprade H, Morin G, Gallardo F, Tremblay-Belzile S, Chartrand P. Cell cycle-dependent spatial segregation of telomerase from sites of DNA damage. J Cell Biol 2017. [PMID: 28637749 PMCID: PMC5551704 DOI: 10.1083/jcb.201610071] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Telomerase can generate a novel telomere at a DNA break, with potentially lethal consequences for the cell. Ouenzar et al. reveal novel roles for Pif1, Rad52, and Siz1-dependent sumoylation in the spatial exclusion of telomerase from sites of DNA repair during the cell cycle. Telomerase can generate a novel telomere at DNA double-strand breaks (DSBs), an event called de novo telomere addition. How this activity is suppressed remains unclear. Combining single-molecule imaging and deep sequencing, we show that the budding yeast telomerase RNA (TLC1 RNA) is spatially segregated to the nucleolus and excluded from sites of DNA repair in a cell cycle–dependent manner. Although TLC1 RNA accumulates in the nucleoplasm in G1/S, Pif1 activity promotes TLC1 RNA localization in the nucleolus in G2/M. In the presence of DSBs, TLC1 RNA remains nucleolar in most G2/M cells but accumulates in the nucleoplasm and colocalizes with DSBs in rad52Δ cells, leading to de novo telomere additions. Nucleoplasmic accumulation of TLC1 RNA depends on Cdc13 localization at DSBs and on the SUMO ligase Siz1, which is required for de novo telomere addition in rad52Δ cells. This study reveals novel roles for Pif1, Rad52, and Siz1-dependent sumoylation in the spatial exclusion of telomerase from sites of DNA repair.
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Affiliation(s)
- Faissal Ouenzar
- Department of Biochemistry and Molecular Medicine, Université de Montréal, Montréal, Quebec, Canada
| | - Maxime Lalonde
- Department of Biochemistry and Molecular Medicine, Université de Montréal, Montréal, Quebec, Canada
| | - Hadrien Laprade
- Department of Biochemistry and Molecular Medicine, Université de Montréal, Montréal, Quebec, Canada
| | - Geneviève Morin
- Department of Biochemistry and Molecular Medicine, Université de Montréal, Montréal, Quebec, Canada
| | - Franck Gallardo
- Department of Biochemistry and Molecular Medicine, Université de Montréal, Montréal, Quebec, Canada
| | - Samuel Tremblay-Belzile
- Department of Biochemistry and Molecular Medicine, Université de Montréal, Montréal, Quebec, Canada
| | - Pascal Chartrand
- Department of Biochemistry and Molecular Medicine, Université de Montréal, Montréal, Quebec, Canada
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Zietzer A, Buschmann EE, Janke D, Li L, Brix M, Meyborg H, Stawowy P, Jungk C, Buschmann I, Hillmeister P. Acute physical exercise and long-term individual shear rate therapy increase telomerase activity in human peripheral blood mononuclear cells. Acta Physiol (Oxf) 2017; 220:251-262. [PMID: 27770498 DOI: 10.1111/apha.12820] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Revised: 06/28/2016] [Accepted: 10/17/2016] [Indexed: 01/03/2023]
Abstract
AIM Physical activity is a potent way to impede vascular ageing. However, patients who suffer from peripheral artery disease (PAD) are often unable to exercise adequately. For those patients, we have developed individual shear rate therapy (ISRT), which is an adaptation of external counterpulsation and enhances endovascular fluid shear stress to increase collateral growth (arteriogenesis). To evaluate the effects of physical exercise and ISRT on the telomere biology of peripheral blood mononuclear cells (PBMCs), we conducted two clinical trials. METHODS In the ISRT-1 study, we assessed PBMC telomerase activity in 26 young healthy volunteers upon a single (short-term) ISRT session and a single treadmill running session. In the ISRT-2 study, we investigated PBMC telomere biology of 14 elderly patients with PAD, who underwent 30 h of (long-term) ISRT within a 5-week period. RESULTS We demonstrate that telomerase activity significantly increased from 39.84 Total Product Generated (TPG) Units ± 6.15 to 58.10 TPG ± 10.46 upon a single treadmill running session in healthy volunteers. In the ISRT-2 trial, PBMC telomerase activity and the mRNA expression of the telomere-protective factor TRF2 increased from 40.87 TPG ± 4.45 to 60.98 TPG ± 6.83 and 2.10-fold ± 0.40, respectively, upon long-term ISRT in elderly patients with PAD. CONCLUSION In summary, we show that acute exercise and long-term ISRT positively affect PBMC telomerase activity, which is indicative for an improved regenerative potential of immune cells and vascular tissues. Long-term ISRT also enhances the gene expression of the telomere-protective factor TRF2.
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Affiliation(s)
- A. Zietzer
- Experimental and Clinical Research Center (ECRC); Richard-Thoma-Laboratories for Arteriogenesis; Center for Cardiovascular Research; Charité - Universitätsmedizin Berlin; Campus Mitte (CCM); Berlin Germany
| | - E. E. Buschmann
- Department for Angiology; Center for Internal Medicine I; Medical University of Brandenburg (MHB); Brandenburg an der Havel Brandenburg Germany
- Institute of Physiology; Charité - Universitätsmedizin Berlin; Campus Mitte (CCM); Berlin Germany
| | - D. Janke
- Berlin-Brandenburg School for Regenerative Therapies (BSRT); Charité - Universitaetsmedizin Berlin; Campus Virchow Klinikum (CVK) and Institute of Chemistry and Biochemistry; Freie Universität Berlin; Berlin Germany
| | - L. Li
- Experimental and Clinical Research Center (ECRC); Richard-Thoma-Laboratories for Arteriogenesis; Center for Cardiovascular Research; Charité - Universitätsmedizin Berlin; Campus Mitte (CCM); Berlin Germany
- Department for Angiology; Center for Internal Medicine I; Medical University of Brandenburg (MHB); Brandenburg an der Havel Brandenburg Germany
| | - M. Brix
- Experimental and Clinical Research Center (ECRC); Richard-Thoma-Laboratories for Arteriogenesis; Center for Cardiovascular Research; Charité - Universitätsmedizin Berlin; Campus Mitte (CCM); Berlin Germany
| | - H. Meyborg
- Department of Medicine/Cardiology; Deutsches Herzzentrum Berlin; Berlin Germany
| | - P. Stawowy
- Department of Medicine/Cardiology; Deutsches Herzzentrum Berlin; Berlin Germany
| | - C. Jungk
- Experimental and Clinical Research Center (ECRC); Richard-Thoma-Laboratories for Arteriogenesis; Center for Cardiovascular Research; Charité - Universitätsmedizin Berlin; Campus Mitte (CCM); Berlin Germany
| | - I. Buschmann
- Experimental and Clinical Research Center (ECRC); Richard-Thoma-Laboratories for Arteriogenesis; Center for Cardiovascular Research; Charité - Universitätsmedizin Berlin; Campus Mitte (CCM); Berlin Germany
- Department for Angiology; Center for Internal Medicine I; Medical University of Brandenburg (MHB); Brandenburg an der Havel Brandenburg Germany
| | - P. Hillmeister
- Experimental and Clinical Research Center (ECRC); Richard-Thoma-Laboratories for Arteriogenesis; Center for Cardiovascular Research; Charité - Universitätsmedizin Berlin; Campus Mitte (CCM); Berlin Germany
- Department for Angiology; Center for Internal Medicine I; Medical University of Brandenburg (MHB); Brandenburg an der Havel Brandenburg Germany
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35
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Valuchova S, Fulnecek J, Prokop Z, Stolt-Bergner P, Janouskova E, Hofr C, Riha K. Protection of Arabidopsis Blunt-Ended Telomeres Is Mediated by a Physical Association with the Ku Heterodimer. THE PLANT CELL 2017; 29:1533-1545. [PMID: 28584163 PMCID: PMC5502450 DOI: 10.1105/tpc.17.00064] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Revised: 05/01/2017] [Accepted: 06/02/2017] [Indexed: 05/15/2023]
Abstract
Telomeres form specialized chromatin that protects natural chromosome termini from being recognized as DNA double-strand breaks. Plants possess unusual blunt-ended telomeres that are unable to form t-loops or complex with single-strand DNA binding proteins, raising the question of the mechanism behind their protection. We have previously suggested that blunt-ended telomeres in Arabidopsis thaliana are protected by Ku, a DNA repair factor with a high affinity for DNA ends. In nonhomologous end joining, Ku loads onto broken DNA via a channel consisting of positively charged amino acids. Here, we demonstrate that while association of Ku with plant telomeres also depends on this channel, Ku's requirements for DNA binding differ between DNA repair and telomere protection. We show that a Ku complex proficient in DNA loading but impaired in translocation along DNA is able to protect blunt-ended telomeres but is deficient in DNA repair. This suggests that Ku physically sequesters blunt-ended telomeres within its DNA binding channel, shielding them from other DNA repair machineries.
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Affiliation(s)
- Sona Valuchova
- Central European Institute of Technology, Masaryk University, 625 00 Brno, Czech Republic
- Gregor Mendel Institute, Austrian Academy of Sciences (OEAW), Vienna Biocenter, 1030 Vienna, Austria
| | - Jaroslav Fulnecek
- Central European Institute of Technology, Masaryk University, 625 00 Brno, Czech Republic
| | - Zbynek Prokop
- Loschmidt Laboratories, Department of Experimental Biology and Research Centre for Toxic Compounds in the Environment, Faculty of Science, Masaryk University, 625 00 Brno, Czech Republic
| | | | - Eliska Janouskova
- Central European Institute of Technology, Masaryk University, 625 00 Brno, Czech Republic
| | - Ctirad Hofr
- Central European Institute of Technology, Masaryk University, 625 00 Brno, Czech Republic
| | - Karel Riha
- Central European Institute of Technology, Masaryk University, 625 00 Brno, Czech Republic
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Hou C, Wang F, Liu X, Chang G, Wang F, Geng X. Comprehensive Analysis of Interaction Networks of Telomerase Reverse Transcriptase with Multiple Bioinformatic Approaches: Deep Mining the Potential Functions of Telomere and Telomerase. Rejuvenation Res 2017; 20:320-333. [PMID: 28281877 DOI: 10.1089/rej.2016.1909] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Telomerase reverse transcriptase (TERT) is the protein component of telomerase complex. Evidence has accumulated showing that the nontelomeric functions of TERT are independent of telomere elongation. However, the mechanisms governing the interaction between TERT and its target genes are not clearly revealed. The biological functions of TERT are not fully elucidated and have thus far been underestimated. To further explore these functions, we investigated TERT interaction networks using multiple bioinformatic databases, including BioGRID, STRING, DAVID, GeneCards, GeneMANIA, PANTHER, miRWalk, mirTarBase, miRNet, miRDB, and TargetScan. In addition, network diagrams were built using Cytoscape software. As competing endogenous RNAs (ceRNAs) are endogenous transcripts that compete for the binding of microRNAs (miRNAs) by using shared miRNA recognition elements, they are involved in creating widespread regulatory networks. Therefore, the ceRNA regulatory networks of TERT were also investigated in this study. Interestingly, we found that the three genes PABPC1, SLC7A11, and TP53 were present in both TERT interaction networks and ceRNAs target genes. It was predicted that TERT might play nontelomeric roles in the generation or development of some rare diseases, such as Rift Valley fever and dyscalculia. Thus, our data will help to decipher the interaction networks of TERT and reveal the unknown functions of telomerase in cancer and aging-related diseases.
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Affiliation(s)
- Chunyu Hou
- 1 Department of Biochemistry and Molecular Biology, Tianjin Medical University , Tianjin, China .,2 Key Laboratory of Cancer Prevention and Therapy, Tianjin Medical University Cancer Institute and Hospital , Tianjin, China
| | - Fei Wang
- 3 Department of Neurology, Tianjin Medical University , Tianjin, China
| | - Xuewen Liu
- 1 Department of Biochemistry and Molecular Biology, Tianjin Medical University , Tianjin, China
| | - Guangming Chang
- 4 Department of Clinical Laboratory, General Hospital, Tianjin Medical University , Tianjin, China
| | - Feng Wang
- 5 Department of Genetics, Tianjin Medical University , Tianjin, China
| | - Xin Geng
- 1 Department of Biochemistry and Molecular Biology, Tianjin Medical University , Tianjin, China .,6 Tianjin Key Laboratory of Cellular and Molecular Immunology, Tianjin Medical University , Tianjin, China .,7 Key Laboratory of Educational Ministry of China, Tianjin Medical University , Tianjin, China
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Ludlow AT, Gratidão L, Ludlow LW, Spangenburg EE, Roth SM. Acute exercise activates p38 MAPK and increases the expression of telomere-protective genes in cardiac muscle. Exp Physiol 2017; 102:397-410. [PMID: 28166612 DOI: 10.1113/ep086189] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2016] [Accepted: 01/20/2017] [Indexed: 12/14/2022]
Abstract
NEW FINDINGS What is the central question of this study? A positive association between telomere length and exercise training has been shown in cardiac tissue of mice. It is currently unknown how each bout of exercise influences telomere-length-regulating proteins. We sought to determine how a bout of exercise altered the expression of telomere-length-regulating genes and a related signalling pathway in cardiac tissue of mice. What is the main finding and its importance? Acute exercise altered the expression of telomere-length-regulating genes in cardiac tissue and might be related to altered mitogen-activated protein kinase signalling. These findings are important in understanding how exercise provides a cardioprotective phenotype with ageing. Age is the greatest risk factor for cardiovascular disease. Telomere length is shorter in the hearts of aged mice compared with young mice, and short telomere length has been associated with an increased risk of cardiovascular disease. One year of voluntary wheel-running exercise attenuates the age-associated loss of telomere length and results in altered gene expression of telomere-length-maintaining and genome-stabilizing proteins in heart tissue of mice. Understanding the early adaptive response of the heart to an endurance exercise bout is paramount to understanding the impact of endurance exercise on heart tissue and cells. To this end, we studied mice before (BL), immediately after (TP1) and 1 h after a treadmill running bout (TP2). We measured the changes in expression of telomere-related genes (shelterin components), DNA-damage-sensing (p53 and Chk2) and DNA-repair genes (Ku70 and Ku80) and mitogen-activated protein kinase (MAPK) signalling. The TP1 animals had increased TRF1 and TRF2 protein and mRNA levels, greater expression of DNA-repair and -response genes (Chk2 and Ku80) and greater protein content of phosphorylated p38 MAPK compared with both BL and TP2 animals. These data provide insights into how physiological stressors remodel the heart tissue and how an early adaptive response mediated by exercise may be maintaining telomere length and/or stabilizing the heart genome through the upregulation of telomere-protective genes.
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Affiliation(s)
- Andrew T Ludlow
- Department of Kinesiology, School of Public Health, University of Maryland at College Park, College Park, MD, USA.,Department of Cell Biology, The University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Laila Gratidão
- Department of Kinesiology, School of Public Health, University of Maryland at College Park, College Park, MD, USA.,Kinesiology Graduate Program, Catholic University of Brasilia, Brasilia, Brazil
| | - Lindsay W Ludlow
- Department of Kinesiology, School of Public Health, University of Maryland at College Park, College Park, MD, USA.,Department of Applied Physiology, Southern Methodist University, Dallas, TX, USA
| | - Espen E Spangenburg
- Department of Physiology, Brody School of Medicine, East Carolina Diabetes and Obesity Institute, East Carolina University, Greenville, NC, USA
| | - Stephen M Roth
- Department of Kinesiology, School of Public Health, University of Maryland at College Park, College Park, MD, USA
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38
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Vasianovich Y, Wellinger RJ. Life and Death of Yeast Telomerase RNA. J Mol Biol 2017; 429:3242-3254. [PMID: 28115201 DOI: 10.1016/j.jmb.2017.01.013] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2016] [Revised: 01/10/2017] [Accepted: 01/14/2017] [Indexed: 12/20/2022]
Abstract
Telomerase reverse transcriptase elongates telomeres to overcome their natural attrition and allow unlimited cellular proliferation, a characteristic shared by stem cells and the majority of malignant cancerous cells. The telomerase holoenzyme comprises a core RNA molecule, a catalytic protein subunit, and other accessory proteins. Malfunction of certain telomerase components can cause serious genetic disorders including dyskeratosis congenita and aplastic anaemia. A hierarchy of tightly regulated steps constitutes the process of telomerase biogenesis, which, if interrupted or misregulated, can impede the production of a functional enzyme and severely affect telomere maintenance. Here, we take a closer look at the budding yeast telomerase RNA component, TLC1, in its long lifetime journey around the cell. We review the extensive knowledge on TLC1 transcription and processing. We focus on exciting recent studies on telomerase assembly, trafficking, and nuclear dynamics, which for the first time unveil striking similarities between the yeast and human telomerase ribonucleoproteins. Finally, we identify questions yet to be answered and new directions to be followed, which, in the future, might improve our knowledge of telomerase biology and trigger the development of new therapies against cancer and other telomerase-related diseases.
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Affiliation(s)
- Yulia Vasianovich
- Department of Microbiology and Infectious Diseases, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Applied Cancer Research Pavillion, 3201 rue Jean-Mignault, Sherbrooke, Quebec, J1E 4K8, Canada.
| | - Raymund J Wellinger
- Department of Microbiology and Infectious Diseases, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Applied Cancer Research Pavillion, 3201 rue Jean-Mignault, Sherbrooke, Quebec, J1E 4K8, Canada.
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Larcher MV, Pasquier E, MacDonald RS, Wellinger RJ. Ku Binding on Telomeres Occurs at Sites Distal from the Physical Chromosome Ends. PLoS Genet 2016; 12:e1006479. [PMID: 27930670 PMCID: PMC5145143 DOI: 10.1371/journal.pgen.1006479] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2016] [Accepted: 11/14/2016] [Indexed: 01/28/2023] Open
Abstract
The Ku complex binds non-specifically to DNA breaks and ensures repair via NHEJ. However, Ku is also known to bind directly to telomeric DNA ends and its presence there is associated with telomere capping, but avoiding NHEJ. How the complex discriminates between a DNA break and a telomeric extremity remains unknown. Our results using a tagged Ku complex, or a chromosome end capturing method, in budding yeast show that yKu association with telomeres can occur at sites distant from the physical end, on sub-telomeric elements, as well as on interstitial telomeric repeats. Consistent with previous studies, our results also show that yKu associates with telomeres in two distinct and independent ways: either via protein-protein interactions between Yku80 and Sir4 or via direct DNA binding. Importantly, yKu associates with the new sites reported here via both modes. Therefore, in sir4Δ cells, telomere bound yKu molecules must have loaded from a DNA-end near the transition of non-telomeric to telomeric repeat sequences. Such ends may have been one sided DNA breaks that occur as a consequence of stalled replication forks on or near telomeric repeat DNA. Altogether, the results predict a new model for yKu function at telomeres that involves yKu binding at one-sided DNA breaks caused by replication stalling. On telomere proximal chromatin, this binding is not followed by initiation of non-homologous end-joining, but rather by break-induced replication or repeat elongation by telomerase. After repair, the yKu-distal portion of telomeres is bound by Rap1, which in turn reduces the potential for yKu to mediate NHEJ. These results thus propose a solution to a long-standing conundrum, namely how to accommodate the apparently conflicting functions of Ku on telomeres. The Ku complex binds to and mediates the rejoining of two DNA ends that were generated by a double-stranded DNA break in the genome. However, Ku is known to be present at telomeres as well. If it would induce end-to-end joining there, it would create chromosome end-fusions that inevitably will lead to gross chromosome rearrangements and genome instability, common hallmarks for cancer initiation. Our results here show that Ku actually is associated with sites on telomeric regions that are distant from the physical ends of the chromosomes. We propose that this association serves to rescue DNA replication that has difficulty passing through telomeric chromatin. If so called one-sided breaks occur near or in telomeric repeats, they will generate critically short telomeres that need to be elongated. The binding of Ku may thus either facilitate the establishment of a specialized end-copying mechanism, called break induced replication or aid in recruiting telomerase to the short ends. These findings thus propose ways to potential solutions for the major conceptual problem that arose with the finding that Ku is associated with telomeres.
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Affiliation(s)
- Mélanie V. Larcher
- Department of Microbiology and Infectious Diseases, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Canada
| | - Emeline Pasquier
- Department of Microbiology and Infectious Diseases, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Canada
| | - R. Stephen MacDonald
- Department of Microbiology and Infectious Diseases, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Canada
| | - Raymund J. Wellinger
- Department of Microbiology and Infectious Diseases, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Canada
- * E-mail:
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40
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Kyriakou D, Stavrou E, Demosthenous P, Angelidou G, San Luis BJ, Boone C, Promponas VJ, Kirmizis A. Functional characterisation of long intergenic non-coding RNAs through genetic interaction profiling in Saccharomyces cerevisiae. BMC Biol 2016; 14:106. [PMID: 27927215 PMCID: PMC5142380 DOI: 10.1186/s12915-016-0325-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2016] [Accepted: 11/09/2016] [Indexed: 01/07/2023] Open
Abstract
BACKGROUND Transcriptome studies have revealed that many eukaryotic genomes are pervasively transcribed producing numerous long non-coding RNAs (lncRNAs). However, only a few lncRNAs have been ascribed a cellular role thus far, with most regulating the expression of adjacent genes. Even less lncRNAs have been annotated as essential hence implying that the majority may be functionally redundant. Therefore, the function of lncRNAs could be illuminated through systematic analysis of their synthetic genetic interactions (GIs). RESULTS Here, we employ synthetic genetic array (SGA) in Saccharomyces cerevisiae to identify GIs between long intergenic non-coding RNAs (lincRNAs) and protein-coding genes. We first validate this approach by demonstrating that the telomerase RNA TLC1 displays a GI network that corresponds to its well-described function in telomere length maintenance. We subsequently performed SGA screens on a set of uncharacterised lincRNAs and uncover their connection to diverse cellular processes. One of these lincRNAs, SUT457, exhibits a GI profile associating it to telomere organisation and we consistently demonstrate that SUT457 is required for telomeric overhang homeostasis through an Exo1-dependent pathway. Furthermore, the GI profile of SUT457 is distinct from that of its neighbouring genes suggesting a function independent to its genomic location. Accordingly, we show that ectopic expression of this lincRNA suppresses telomeric overhang accumulation in sut457Δ cells assigning a trans-acting role for SUT457 in telomere biology. CONCLUSIONS Overall, our work proposes that systematic application of this genetic approach could determine the functional significance of individual lncRNAs in yeast and other complex organisms.
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Affiliation(s)
- Dimitris Kyriakou
- Department of Biological Sciences, University of Cyprus, Nicosia, CY-1678, Cyprus
| | - Emmanouil Stavrou
- Department of Biological Sciences, University of Cyprus, Nicosia, CY-1678, Cyprus
| | | | - Georgia Angelidou
- Department of Biological Sciences, University of Cyprus, Nicosia, CY-1678, Cyprus
| | - Bryan-Joseph San Luis
- The Donnelly Centre, University of Toronto, 160 College Street, Toronto, Ontario, M5S 3E1, Canada
| | - Charles Boone
- The Donnelly Centre, University of Toronto, 160 College Street, Toronto, Ontario, M5S 3E1, Canada
| | - Vasilis J Promponas
- Department of Biological Sciences, University of Cyprus, Nicosia, CY-1678, Cyprus
| | - Antonis Kirmizis
- Department of Biological Sciences, University of Cyprus, Nicosia, CY-1678, Cyprus.
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41
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Anisenko AN, Knyazhanskaya ES, Zatsepin TS, Gottikh MB. Human Ku70 protein binds hairpin RNA and double stranded DNA through two different sites. Biochimie 2016; 132:85-93. [PMID: 27825805 DOI: 10.1016/j.biochi.2016.11.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2016] [Accepted: 11/02/2016] [Indexed: 02/07/2023]
Abstract
Human protein Ku usually functions in the cell as a complex of two subunits, Ku70 and Ku80. The Ku heterodimer plays a key role in the non-homologous end joining DNA repair pathway by specifically recognizing the DNA ends at the site of the lesion. The binding of the Ku heterodimer to DNA has been well-studied, and its interactions with RNA have been also described. However, Ku70 subunit is known to have independent DNA binding capability, which is less characterized. RNA binding properties of Ku70 have not been yet specially studied. We have prepared recombinant full-length Ku70 and a set of its truncated mutants in E. coli, and studied their interactions with nucleic acids of various structures: linear single- and double-stranded DNA and RNA, as well as closed circular DNA and hairpin RNA. Ku70 has demonstrated a high affinity binding to double stranded DNA and hairpin RNA with a certain structure only. Interestingly, in contrast to the Ku heterodimer, Ku70 is found to interact with closed circular DNA. We also show for the first time that Ku70 employs two different sites for DNA and RNA binding. The double-stranded DNA is recognized by the C-terminal part of Ku70 including SAP domain as it has been earlier demonstrated, whereas hairpin RNA binding is provided by amino acids 251-438.
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Affiliation(s)
- Andrey N Anisenko
- Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow, Russia.
| | | | - Timofey S Zatsepin
- Chemistry Department, Lomonosov Moscow State University, Moscow, Russia; Skolkovo Institute of Science and Technology, Skolkovo, Russia.
| | - Marina B Gottikh
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia.
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42
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Laprade H, Lalonde M, Guérit D, Chartrand P. Live-cell imaging of budding yeast telomerase RNA and TERRA. Methods 2016; 114:46-53. [PMID: 27474163 DOI: 10.1016/j.ymeth.2016.07.014] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Revised: 07/11/2016] [Accepted: 07/23/2016] [Indexed: 02/02/2023] Open
Abstract
In most eukaryotes, the ribonucleoprotein complex telomerase is responsible for maintaining telomere length. In recent years, single-cell microscopy techniques such as fluorescent in situ hybridization and live-cell imaging have been developed to image the RNA subunit of the telomerase holoenzyme. These techniques are now becoming important tools for the study of telomerase biogenesis, its association with telomeres and its regulation. Here, we present detailed protocols for live-cell imaging of the Saccharomyces cerevisiae telomerase RNA subunit, called TLC1, and also of the non-coding telomeric repeat-containing RNA TERRA. We describe the approach used for genomic integration of MS2 stem-loops in these transcripts, and provide information for optimal live-cell imaging of these non-coding RNAs.
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Affiliation(s)
- Hadrien Laprade
- Department of Biochemistry and Molecular Medicine, Université de Montréal, Montréal, Qc H3C 3J7, Canada
| | - Maxime Lalonde
- Department of Biochemistry and Molecular Medicine, Université de Montréal, Montréal, Qc H3C 3J7, Canada
| | - David Guérit
- Department of Biochemistry and Molecular Medicine, Université de Montréal, Montréal, Qc H3C 3J7, Canada
| | - Pascal Chartrand
- Department of Biochemistry and Molecular Medicine, Université de Montréal, Montréal, Qc H3C 3J7, Canada.
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43
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Finding a place in the SUN: telomere maintenance in a diverse nuclear landscape. Curr Opin Cell Biol 2016; 40:145-152. [PMID: 27064212 DOI: 10.1016/j.ceb.2016.03.011] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Revised: 03/15/2016] [Accepted: 03/18/2016] [Indexed: 11/21/2022]
Abstract
Telomeres function in the context of a complex nuclear milieu in which telomeres tend to occupy distinct subnuclear regions. Indeed, regulation of the subnuclear positioning of telomeres is conserved from yeast to human, raising the age-old question: to what extent is location important for function? In mitotically dividing cells, the positioning of telomeres affects their epigenetic state and influences telomere processing and synthesis. In meiotic cells, telomere location is important for homologue pairing, centromere assembly and spindle formation. Here we focus on recent insights into the functions of telomere positioning in maintaining genome integrity.
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44
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Conrad T, Albrecht AS, de Melo Costa VR, Sauer S, Meierhofer D, Ørom UA. Serial interactome capture of the human cell nucleus. Nat Commun 2016; 7:11212. [PMID: 27040163 PMCID: PMC4822031 DOI: 10.1038/ncomms11212] [Citation(s) in RCA: 98] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2015] [Accepted: 03/02/2016] [Indexed: 11/15/2022] Open
Abstract
Novel RNA-guided cellular functions are paralleled by an increasing number of RNA-binding proteins (RBPs). Here we present 'serial RNA interactome capture' (serIC), a multiple purification procedure of ultraviolet-crosslinked poly(A)-RNA-protein complexes that enables global RBP detection with high specificity. We apply serIC to the nuclei of proliferating K562 cells to obtain the first human nuclear RNA interactome. The domain composition of the 382 identified nuclear RBPs markedly differs from previous IC experiments, including few factors without known RNA-binding domains that are in good agreement with computationally predicted RNA binding. serIC extends the number of DNA-RNA-binding proteins (DRBPs), and reveals a network of RBPs involved in p53 signalling and double-strand break repair. serIC is an effective tool to couple global RBP capture with additional selection or labelling steps for specific detection of highly purified RBPs.
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Affiliation(s)
- Thomas Conrad
- Max Planck Institute for Molecular Genetics, Otto Warburg Laboratories, 14195 Berlin, Germany
| | - Anne-Susann Albrecht
- Max Planck Institute for Molecular Genetics, Otto Warburg Laboratories, 14195 Berlin, Germany
- Department of Biochemistry, Free University of Berlin, 14195 Berlin, Germany
| | - Veronica Rodrigues de Melo Costa
- Max Planck Institute for Molecular Genetics, Otto Warburg Laboratories, 14195 Berlin, Germany
- Department of Informatics, Free University of Berlin, 14195 Berlin, Germany
| | - Sascha Sauer
- Max Planck Institute for Molecular Genetics, Otto Warburg Laboratories, 14195 Berlin, Germany
- CU Systems Medicine, 97080 Würzburg 14195, Germany
| | - David Meierhofer
- Max Planck Institute for Molecular Genetics, Mass Spectrometry Core Facility, 14195 Berlin, Germany
| | - Ulf Andersson Ørom
- Max Planck Institute for Molecular Genetics, Otto Warburg Laboratories, 14195 Berlin, Germany
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45
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Lamaa A, Le Bras M, Skuli N, Britton S, Frit P, Calsou P, Prats H, Cammas A, Millevoi S. A novel cytoprotective function for the DNA repair protein Ku in regulating p53 mRNA translation and function. EMBO Rep 2016; 17:508-18. [PMID: 26964895 DOI: 10.15252/embr.201541181] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2015] [Accepted: 01/27/2016] [Indexed: 12/11/2022] Open
Abstract
Ku heterodimer is a DNA binding protein with a prominent role in DNA repair. Here, we investigate whether and how Ku impacts the DNA damage response by acting as a post-transcriptional regulator of gene expression. We show that Ku represses p53 protein synthesis and p53-mediated apoptosis by binding to a bulged stem-loop structure within the p53 5' UTR However, Ku-mediated translational repression of the p53 mRNA is relieved after genotoxic stress. The underlying mechanism involves Ku acetylation which disrupts Ku-p53 mRNA interactions. These results suggest that Ku-mediated repression of p53 mRNA translation constitutes a novel mechanism linking DNA repair and mRNA translation.
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Affiliation(s)
- Assala Lamaa
- Cancer Research Center of Toulouse (CRCT), Inserm UMR 1037 Université Toulouse III-Paul Sabatier, Toulouse, France
| | - Morgane Le Bras
- Cancer Research Center of Toulouse (CRCT), Inserm UMR 1037 Université Toulouse III-Paul Sabatier, Toulouse, France
| | - Nicolas Skuli
- Cancer Research Center of Toulouse (CRCT), Inserm UMR 1037 Université Toulouse III-Paul Sabatier, Toulouse, France
| | - Sébastien Britton
- Institut de Pharmacologie et de Biologie Structurale, Université de Toulouse, CNRS UPS, France Equipe labellisée Ligue Nationale Contre le Cancer
| | - Philippe Frit
- Institut de Pharmacologie et de Biologie Structurale, Université de Toulouse, CNRS UPS, France Equipe labellisée Ligue Nationale Contre le Cancer
| | - Patrick Calsou
- Institut de Pharmacologie et de Biologie Structurale, Université de Toulouse, CNRS UPS, France Equipe labellisée Ligue Nationale Contre le Cancer
| | - Hervé Prats
- Cancer Research Center of Toulouse (CRCT), Inserm UMR 1037 Université Toulouse III-Paul Sabatier, Toulouse, France
| | - Anne Cammas
- Cancer Research Center of Toulouse (CRCT), Inserm UMR 1037 Université Toulouse III-Paul Sabatier, Toulouse, France
| | - Stefania Millevoi
- Cancer Research Center of Toulouse (CRCT), Inserm UMR 1037 Université Toulouse III-Paul Sabatier, Toulouse, France
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Millet C, Makovets S. Aneuploidy as a mechanism of adaptation to telomerase insufficiency. Curr Genet 2016; 62:557-64. [PMID: 26758992 PMCID: PMC4929173 DOI: 10.1007/s00294-015-0559-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Revised: 12/20/2015] [Accepted: 12/24/2015] [Indexed: 12/01/2022]
Abstract
Cells’ survival is determined by their ability to adapt to constantly changing environment. Adaptation responses involve global changes in transcription, translation, and posttranslational modifications of proteins. In recent years, karyotype changes in adapting populations of single cell organisms have been reported in a number of studies. More recently, we have described aneuploidy as an adaptation mechanism used by populations of budding yeast Saccharomyces cerevisiae to survive telomerase insufficiency induced by elevated growth temperature. Genetic evidence suggests that telomerase insufficiency is caused by decreased levels of the telomerase catalytic subunit Est2. Here, we present experiments arguing that the underlying cause of this phenomenon may be within the telomerase RNA TLC1: changes in the expression of TLC1 as well as mutations in the TLC1 template region affect telomere length equilibrium and the temperature threshold for the induction of telomerase insufficiency. We discuss what lies at the root of telomerase insufficiency, how cell populations overcome it through aneuploidy and whether reversible aneuploidy could be an adaptation mechanism for a variety of environmental stresses.
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Affiliation(s)
- Caroline Millet
- School of Biological Sciences, Institute of Cell Biology, University of Edinburgh, Roger Land Building Room 1.07, Alexander Crum Brown Road, Edinburgh, EH9 3FF, UK
| | - Svetlana Makovets
- School of Biological Sciences, Institute of Cell Biology, University of Edinburgh, Roger Land Building Room 1.07, Alexander Crum Brown Road, Edinburgh, EH9 3FF, UK.
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47
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Byun MY, Cui LH, Kim WT. Suppression of OsKu80 results in defects in developmental growth and increased telomere length in rice (Oryza sativa L.). Biochem Biophys Res Commun 2015; 468:857-62. [PMID: 26590017 DOI: 10.1016/j.bbrc.2015.11.044] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2015] [Accepted: 11/09/2015] [Indexed: 10/22/2022]
Abstract
The Ku70-Ku80 heterodimer plays a critical role in the maintenance of genomic stability in humans and yeasts. In this report, we identified and characterized OsKu80 in rice, a model monocot crop. OsKu80 forms a heterodimer with OsKu70 in yeast and plant cells, as demonstrated by yeast two-hybrid, in vivo co-immunoprecipitation, and bimolecular fluorescence complementation assays. RNAi-mediated knock-down T3 transgenic rice plants (Ubi:RNAi-OsKu80) displayed a retarded growth phenotype at the post-germination stage. In addition, the Ubi:RNAi-OsKu80 knock-down progeny exhibited noticeably increased telomere length as compared to wild-type rice. These results are discussed with the idea that OsKu80 plays a role in developmental growth and telomere length regulation in rice plants.
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Affiliation(s)
- Mi Young Byun
- Department of Systems Biology, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, South Korea
| | - Li Hua Cui
- Department of Systems Biology, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, South Korea
| | - Woo Taek Kim
- Department of Systems Biology, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749, South Korea.
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48
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Hass EP, Zappulla DC. The Ku subunit of telomerase binds Sir4 to recruit telomerase to lengthen telomeres in S. cerevisiae. eLife 2015. [PMID: 26218225 PMCID: PMC4547093 DOI: 10.7554/elife.07750] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
In Saccharomyces cerevisiae and in humans, the telomerase RNA subunit is bound by Ku, a ring-shaped protein heterodimer best known for its function in DNA repair. Ku binding to yeast telomerase RNA promotes telomere lengthening and telomerase recruitment to telomeres, but how this is achieved remains unknown. Using telomere-length analysis and chromatin immunoprecipitation, we show that Sir4 – a previously identified Ku-binding protein that is a component of telomeric silent chromatin – is required for Ku-mediated telomere lengthening and telomerase recruitment. We also find that specifically tethering Sir4 directly to Ku-binding-defective telomerase RNA restores otherwise-shortened telomeres to wild-type length. These findings suggest that Sir4 is the telomere-bound target of Ku-mediated telomerase recruitment and provide one mechanism for how the Sir4-competing Rif1 and Rif2 proteins negatively regulate telomere length in yeast. DOI:http://dx.doi.org/10.7554/eLife.07750.001 Inside a cell's nucleus, DNA is packaged into structures called chromosomes. The ends of every chromosome are capped by repeating sequences of DNA known as telomeres, which protect the chromosomes from damage. Every time a cell divides, the telomeres shorten. If telomere length falls below a critical level, the cell can die or enter a state in which it can no longer divide. During cell division, an enzyme called telomerase normally restores telomeres to their original length. Telomerase is made up of several proteins and an RNA molecule. In yeast and humans, a protein called Ku is one part of the telomerase enzyme. Ku binds to the RNA subunit of telomerase and helps the enzyme find and interact with the telomeres. Previous research has shown that Ku is unable to work alone to recruit telomerase to the chromosome. A protein called Sir4 binds to telomeres and cells lacking it have short telomeres, but the reason behind this was not known. Hass and Zappulla confirmed previous reports that Ku binds to Sir4 using a biochemical approach. Additional experiments provided genetic evidence that this binding interaction is important for telomerase to lengthen telomeres appropriately. Cells in which the RNA subunit of telomerase is unable to bind effectively to Ku have short telomeres. Hass and Zappulla directly tethered Sir4 to this defective RNA and found this restored the shortened telomeres to a normal length, indicating that Sir4 normally binds Ku to recruit telomerase. Discovering this mode of recruitment also helps to explain how two other telomeric proteins (Rif1 and 2) limit telomere lengthening; they compete with Ku-Sir4 recruitment to form a length-regulating system. Taken together, Hass and Zappulla's results provide strong evidence that Sir4 cooperates with Ku to control the lengthening of chromosome ends. Future research will hopefully reveal the precise space and time requirements for this telomerase-controlling system in yeast. Additionally, because Ku has been reported to be a subunit of human telomerase, future studies could also explore whether human cells use a similar strategy. DOI:http://dx.doi.org/10.7554/eLife.07750.002
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Affiliation(s)
- Evan P Hass
- Department of Biology, Johns Hopkins University, Baltimore, United States
| | - David C Zappulla
- Department of Biology, Johns Hopkins University, Baltimore, United States
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Marcand S. How do telomeres and NHEJ coexist? Mol Cell Oncol 2014; 1:e963438. [PMID: 27308342 PMCID: PMC4904885 DOI: 10.4161/23723548.2014.963438] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2014] [Revised: 08/01/2014] [Accepted: 08/07/2014] [Indexed: 12/21/2022]
Abstract
The telomeres of eukaryotes are stable open double-strand ends that coexist with nonhomologous end joining (NHEJ), the repair pathway that directly ligates DNA ends generated by double-strand breaks. Since a single end-joining event between 2 telomeres generates a circular chromosome or an unstable dicentric chromosome, NHEJ must be prevented from acting on telomeres. Multiple mechanisms mediated by telomere factors act in synergy to achieve this inhibition.
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Affiliation(s)
- Stéphane Marcand
- CEA; DSV/IRCM/SIGRR/LTR; Fontenay-aux-roses; France; INSERM UMR 967; Fontenay-aux-roses; France
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Vasianovich Y, Harrington LA, Makovets S. Break-induced replication requires DNA damage-induced phosphorylation of Pif1 and leads to telomere lengthening. PLoS Genet 2014; 10:e1004679. [PMID: 25329304 PMCID: PMC4199488 DOI: 10.1371/journal.pgen.1004679] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2014] [Accepted: 08/18/2014] [Indexed: 11/18/2022] Open
Abstract
Broken replication forks result in DNA breaks that are normally repaired via homologous recombination or break induced replication (BIR). Mild insufficiency in the replicative ligase Cdc9 in budding yeast Saccharomyces cerevisiae resulted in a population of cells with persistent DNA damage, most likely due to broken replication forks, constitutive activation of the DNA damage checkpoint and longer telomeres. This telomere lengthening required functional telomerase, the core DNA damage signaling cascade Mec1-Rad9-Rad53, and the components of the BIR repair pathway - Rad51, Rad52, Pol32, and Pif1. The Mec1-Rad53 induced phosphorylation of Pif1, previously found necessary for inhibition of telomerase at double strand breaks, was also important for the role of Pif1 in BIR and telomere elongation in cdc9-1 cells. Two other mutants with impaired DNA replication, cdc44-5 and rrm3Δ, were similar to cdc9-1: their long telomere phenotype was dependent on the Pif1 phosphorylation locus. We propose a model whereby the passage of BIR forks through telomeres promotes telomerase activity and leads to telomere lengthening.
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Affiliation(s)
- Yulia Vasianovich
- Institute of Cell Biology, University of Edinburgh, Edinburgh, United Kingdom
| | - Lea A. Harrington
- Institute of Cell Biology, University of Edinburgh, Edinburgh, United Kingdom
- Institut de Recherche en Immunologie et en Cancérologie, Université de Montréal, Montréal, Québec, Canada
| | - Svetlana Makovets
- Institute of Cell Biology, University of Edinburgh, Edinburgh, United Kingdom
- * E-mail:
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