1
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Carvalho Borges PC, Bouabboune C, Escandell JM, Matmati S, Coulon S, Ferreira MG. Pot1 promotes telomere DNA replication via the Stn1-Ten1 complex in fission yeast. Nucleic Acids Res 2023; 51:12325-12336. [PMID: 37953281 PMCID: PMC10711446 DOI: 10.1093/nar/gkad1036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Revised: 10/19/2023] [Accepted: 10/31/2023] [Indexed: 11/14/2023] Open
Abstract
Telomeres are nucleoprotein complexes that protect the chromosome-ends from eliciting DNA repair while ensuring their complete duplication. Pot1 is a subunit of telomere capping complex that binds to the G-rich overhang and inhibits the activation of DNA damage checkpoints. In this study, we explore new functions of fission yeast Pot1 by using a pot1-1 temperature sensitive mutant. We show that pot1 inactivation impairs telomere DNA replication resulting in the accumulation of ssDNA leading to the complete loss of telomeric DNA. Recruitment of Stn1 to telomeres, an auxiliary factor of DNA lagging strand synthesis, is reduced in pot1-1 mutants and overexpression of Stn1 rescues loss of telomeres and cell viability at restrictive temperature. We propose that Pot1 plays a crucial function in telomere DNA replication by recruiting Stn1-Ten1 and Polα-primase complex to telomeres via Tpz1, thus promoting lagging-strand DNA synthesis at stalled replication forks.
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Affiliation(s)
| | - Chaïnez Bouabboune
- CNRS, INSERM, Aix Marseille Univ, Institut Paoli-Calmettes, CRCM, Equipe labellisée par la Ligue Nationale contre le Cancer, Marseille, F-13009, France
| | | | - Samah Matmati
- CNRS, INSERM, Aix Marseille Univ, Institut Paoli-Calmettes, CRCM, Equipe labellisée par la Ligue Nationale contre le Cancer, Marseille, F-13009, France
| | - Stéphane Coulon
- CNRS, INSERM, Aix Marseille Univ, Institut Paoli-Calmettes, CRCM, Equipe labellisée par la Ligue Nationale contre le Cancer, Marseille, F-13009, France
| | - Miguel Godinho Ferreira
- Instituto Gulbenkian de Ciência, Oeiras, 2781-901, Portugal
- Institute for Research on Cancer and Aging of Nice (IRCAN), INSERM U1081 UMR7284 CNRS, 06107 Nice, France
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2
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Singh P, Gazy I, Kupiec M. Control of telomere length in yeast by SUMOylated PCNA and the Elg1 PCNA unloader. eLife 2023; 12:RP86990. [PMID: 37530521 PMCID: PMC10396338 DOI: 10.7554/elife.86990] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/03/2023] Open
Abstract
Telomeres cap and protect the linear eukaryotic chromosomes. Telomere length is determined by an equilibrium between positive and negative regulators of telomerase activity. A systematic screen for yeast mutants that affect telomere length maintenance in the yeast Saccharomyces cerevisiae revealed that mutations in any of ~500 genes affects telomere length. One of the genes that, when mutated, causes telomere elongation is ELG1, which encodes an unloader of PCNA, the processivity factor for replicative DNA polymerases. PCNA can undergo SUMOylation on two conserved residues, K164 and K127, or ubiquitination at lysine 164. These modifications have already been implicated in genome stability processes. We report that SUMOylated PCNA acts as a signal that positively regulates telomerase activity. We also uncovered physical interactions between Elg1 and the CST (Cdc13-Stn1-Ten) complex and addressed the mechanism by which Elg1 and Stn1 negatively regulates telomere elongation, coordinated by SUMO. We discuss these results with respect to how chromosomal replication and telomere elongation are coordinated.
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Affiliation(s)
- Pragyan Singh
- The Shmunis School of Biomedicine and Cancer Research, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Inbal Gazy
- The Shmunis School of Biomedicine and Cancer Research, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
| | - Martin Kupiec
- The Shmunis School of Biomedicine and Cancer Research, The George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
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3
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Vaurs M, Naiman K, Bouabboune C, Rai S, Ptasińska K, Rives M, Matmati S, Carr AM, Géli V, Coulon S. Stn1-Ten1 and Taz1 independently promote replication of subtelomeric fragile sequences in fission yeast. Cell Rep 2023; 42:112537. [PMID: 37243596 DOI: 10.1016/j.celrep.2023.112537] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Revised: 03/01/2023] [Accepted: 05/03/2023] [Indexed: 05/29/2023] Open
Abstract
Efficient replication of terminal DNA is crucial to maintain telomere stability. In fission yeast, Taz1 and the Stn1-Ten1 (ST) complex play prominent roles in DNA-ends replication. However, their function remains elusive. Here, we have analyzed genome-wide replication and show that ST does not affect genome-wide replication but is crucial for the efficient replication of a subtelomeric region called STE3-2. We further show that, when ST function is compromised, a homologous recombination (HR)-based fork restart mechanism becomes necessary for STE3-2 stability. While both Taz1 and Stn1 bind to STE3-2, we find that the STE3-2 replication function of ST is independent of Taz1 but relies on its association with the shelterin proteins Pot1-Tpz1-Poz1. Finally, we demonstrate that the firing of an origin normally inhibited by Rif1 can circumvent the replication defect of subtelomeres when ST function is compromised. Our results help illuminate why fission yeast telomeres are terminal fragile sites.
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Affiliation(s)
- Mélina Vaurs
- CNRS, INSERM, Aix Marseille Univ, Institut Paoli-Calmettes, CRCM, Ligue Nationale Contre le Cancer (équipe labellisée), Marseille, France
| | - Karel Naiman
- CNRS, INSERM, Aix Marseille Univ, Institut Paoli-Calmettes, CRCM, Ligue Nationale Contre le Cancer (équipe labellisée), Marseille, France; Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer BN1 9RQ, UK
| | - Chaïnez Bouabboune
- CNRS, INSERM, Aix Marseille Univ, Institut Paoli-Calmettes, CRCM, Ligue Nationale Contre le Cancer (équipe labellisée), Marseille, France
| | - Sudhir Rai
- CNRS, INSERM, Aix Marseille Univ, Institut Paoli-Calmettes, CRCM, Ligue Nationale Contre le Cancer (équipe labellisée), Marseille, France
| | - Katarzyna Ptasińska
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer BN1 9RQ, UK
| | - Marion Rives
- CNRS, INSERM, Aix Marseille Univ, Institut Paoli-Calmettes, CRCM, Ligue Nationale Contre le Cancer (équipe labellisée), Marseille, France
| | - Samah Matmati
- CNRS, INSERM, Aix Marseille Univ, Institut Paoli-Calmettes, CRCM, Ligue Nationale Contre le Cancer (équipe labellisée), Marseille, France
| | - Antony M Carr
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer BN1 9RQ, UK
| | - Vincent Géli
- CNRS, INSERM, Aix Marseille Univ, Institut Paoli-Calmettes, CRCM, Ligue Nationale Contre le Cancer (équipe labellisée), Marseille, France.
| | - Stéphane Coulon
- CNRS, INSERM, Aix Marseille Univ, Institut Paoli-Calmettes, CRCM, Ligue Nationale Contre le Cancer (équipe labellisée), Marseille, France.
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4
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Wang H, Ma T, Zhang X, Chen W, Lan Y, Kuang G, Hsu SJ, He Z, Chen Y, Stewart J, Bhattacharjee A, Luo Z, Price C, Feng X. CTC1 OB-B interaction with TPP1 terminates telomerase and prevents telomere overextension. Nucleic Acids Res 2023; 51:4914-4928. [PMID: 37021555 PMCID: PMC10250220 DOI: 10.1093/nar/gkad237] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Revised: 03/16/2023] [Accepted: 03/31/2023] [Indexed: 04/07/2023] Open
Abstract
CST (CTC1-STN1-TEN1) is a telomere associated complex that binds ssDNA and is required for multiple steps in telomere replication, including termination of G-strand extension by telomerase and synthesis of the complementary C-strand. CST contains seven OB-folds which appear to mediate CST function by modulating CST binding to ssDNA and the ability of CST to recruit or engage partner proteins. However, the mechanism whereby CST achieves its various functions remains unclear. To address the mechanism, we generated a series of CTC1 mutants and studied their effect on CST binding to ssDNA and their ability to rescue CST function in CTC1-/- cells. We identified the OB-B domain as a key determinant of telomerase termination but not C-strand synthesis. CTC1-ΔB expression rescued C-strand fill-in, prevented telomeric DNA damage signaling and growth arrest. However, it caused progressive telomere elongation and the accumulation of telomerase at telomeres, indicating an inability to limit telomerase action. The CTC1-ΔB mutation greatly reduced CST-TPP1 interaction but only modestly affected ssDNA binding. OB-B point mutations also weakened TPP1 association, with the deficiency in TPP1 interaction tracking with an inability to limit telomerase action. Overall, our results indicate that CTC1-TPP1 interaction plays a key role in telomerase termination.
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Affiliation(s)
- Huan Wang
- Department of Pediatrics, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, China
- Institute of Precision Medicine, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Tengfei Ma
- Department of Pediatrics, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, China
- Institute of Precision Medicine, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Xiaotong Zhang
- Institute of Precision Medicine, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Wei Chen
- Institute of Precision Medicine, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Yina Lan
- Institute of Precision Medicine, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Guotao Kuang
- Institute of Precision Medicine, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Shih-Jui Hsu
- Department of Cancer Biology, University of Cincinnati, Cincinnati, OH, USA
| | - Zibin He
- MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Yuxi Chen
- MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Jason Stewart
- Department of Biological Sciences, University of South Carolina, Columbia, SC, USA
| | | | - Zhenhua Luo
- Department of Pediatrics, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, China
- Institute of Precision Medicine, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, China
| | - Carolyn Price
- Department of Cancer Biology, University of Cincinnati, Cincinnati, OH, USA
| | - Xuyang Feng
- Department of Pediatrics, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, China
- Institute of Precision Medicine, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, China
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5
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Vaurs M, Audry J, Runge KW, Géli V, Coulon S. A proto-telomere is elongated by telomerase in a shelterin-dependent manner in quiescent fission yeast cells. Nucleic Acids Res 2022; 50:11682-11695. [PMID: 36330920 PMCID: PMC9723628 DOI: 10.1093/nar/gkac986] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2022] [Revised: 10/08/2022] [Accepted: 10/17/2022] [Indexed: 11/06/2022] Open
Abstract
Telomere elongation is coupled with genome replication, raising the question of the repair of short telomeres in post-mitotic cells. We investigated the fate of a telomere-repeat capped end that mimics a single short telomere in quiescent fission yeast cells. We show that telomerase is able to elongate this single short telomere during quiescence despite the binding of Ku to the proto-telomere. While Taz1 and Rap1 repress telomerase in vegetative cells, both shelterin proteins are required for efficient telomere extension in quiescent cells, underscoring a distinct mode of telomerase control. We further show that Rad3ATR and Tel1ATM are redundantly required for telomere elongation in quiescence through the phosphorylation of Ccq1 and that Rif1 and its associated-PP1 phosphatases negatively regulate telomerase activity by opposing Ccq1 phosphorylation. The distinct mode of telomerase regulation in quiescent fission yeast cells may be relevant to that in human stem and progenitor cells.
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Affiliation(s)
- Mélina Vaurs
- CNRS, INSERM, Aix Marseille Univ, Institut Paoli-Calmettes, CRCM, Equipe labellisée par la Ligue Nationale contre le Cancer, Marseille, F-13009, France
| | - Julien Audry
- Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, OH, USA
| | - Kurt W Runge
- Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, OH, USA,Department of Genetics and Genome Sciences, Case Western Reserve University, Cleveland, OH, USA
| | - Vincent Géli
- Correspondence may also be addressed to Vincent Géli.
| | - Stéphane Coulon
- To whom correspondence should be addressed. Tel: +33 4 86 97 74 07; Fax: +33 4 86 97 74 99;
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6
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Mennie AK, Moser BA, Hoyle A, Low RS, Tanaka K, Nakamura TM. Tpz1 TPP1 prevents telomerase activation and protects telomeres by modulating the Stn1-Ten1 complex in fission yeast. Commun Biol 2019; 2:297. [PMID: 31396577 PMCID: PMC6686008 DOI: 10.1038/s42003-019-0546-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Accepted: 07/15/2019] [Indexed: 12/24/2022] Open
Abstract
In both mammalian and fission yeast cells, conserved shelterin and CST (CTC1-STN1-TEN1) complexes play critical roles in protection of telomeres and regulation of telomerase, an enzyme required to overcome the end replication problem. However, molecular details that govern proper coordination among shelterin, CST, and telomerase have not yet been fully understood. Here, we establish a conserved SWSSS motif, located adjacent to the Lys242 SUMOylation site in the fission yeast shelterin subunit Tpz1, as a new functional regulatory element for telomere protection and telomere length homeostasis. The SWSSS motif works redundantly with Lys242 SUMOylation to promote binding of Stn1-Ten1 at telomere and sub-telomere regions to protect against single-strand annealing (SSA)-dependent telomere fusions, and to prevent telomerase accumulation at telomeres. In addition, we provide evidence that the SWSSS motif defines an unanticipated role of Tpz1 in limiting telomerase activation at telomeres to prevent uncontrolled telomere elongation.
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Affiliation(s)
- Amanda K. Mennie
- Department of Biochemistry and Molecular Genetics, College of Medicine, University of Illinois at Chicago, Chicago, IL 60607 USA
| | - Bettina A. Moser
- Department of Biochemistry and Molecular Genetics, College of Medicine, University of Illinois at Chicago, Chicago, IL 60607 USA
| | - Alice Hoyle
- Department of Biochemistry and Molecular Genetics, College of Medicine, University of Illinois at Chicago, Chicago, IL 60607 USA
| | - Ross S. Low
- Department of Biochemistry and Molecular Genetics, College of Medicine, University of Illinois at Chicago, Chicago, IL 60607 USA
- Present Address: Earlham Institute, Norwich Research Park, Norwich, NR4 7UZ United Kingdom
| | - Katsunori Tanaka
- Department of Bioscience, School of Science and Technology, Kwansei Gakuin University, Sanda, 669-1337 Japan
| | - Toru M. Nakamura
- Department of Biochemistry and Molecular Genetics, College of Medicine, University of Illinois at Chicago, Chicago, IL 60607 USA
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7
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Armstrong CA, Moiseeva V, Collopy LC, Pearson SR, Ullah TR, Xi ST, Martin J, Subramaniam S, Marelli S, Amelina H, Tomita K. Fission yeast Ccq1 is a modulator of telomerase activity. Nucleic Acids Res 2019; 46:704-716. [PMID: 29216371 PMCID: PMC5778466 DOI: 10.1093/nar/gkx1223] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Accepted: 11/27/2017] [Indexed: 01/05/2023] Open
Abstract
Shelterin, the telomeric protein complex, plays a crucial role in telomere homeostasis. In fission yeast, telomerase is recruited to chromosome ends by the shelterin component Tpz1 and its binding partner Ccq1, where telomerase binds to the 3' overhang to add telomeric repeats. Recruitment is initiated by the interaction of Ccq1 with the telomerase subunit Est1. However, how telomerase is released following elongation remains to be established. Here, we show that Ccq1 also has a role in the suppression of telomere elongation, when coupled with the Clr4 histone H3 methyl-transferase complex and the Clr3 histone deacetylase and nucleosome remodelling complex, SHREC. We have dissected the functions of Ccq1 by establishing a Ccq1-Est1 fusion system, which bypasses the telomerase recruitment step. We demonstrate that Ccq1 forms two distinct complexes for positive and negative telomerase regulation, with Est1 and Clr3 respectively. The negative form of Ccq1 promotes dissociation of Ccq1-telomerase from Tpz1, thereby restricting local telomerase activity. The Clr4 complex also has a negative regulation activity with Ccq1, independently of SHREC. Thus, we propose a model in which Ccq1-Est1 recruits telomerase to mediate telomere extension, whilst elongated telomeric DNA recruits Ccq1 with the chromatin-remodelling complexes, which in turn releases telomerase from the telomere.
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Affiliation(s)
- Christine A Armstrong
- Chromosome Maintenance Group, UCL Cancer Institute, University College London, London WC1E 6DD, UK
| | - Vera Moiseeva
- Chromosome Maintenance Group, UCL Cancer Institute, University College London, London WC1E 6DD, UK
| | - Laura C Collopy
- Chromosome Maintenance Group, UCL Cancer Institute, University College London, London WC1E 6DD, UK
| | - Siân R Pearson
- Chromosome Maintenance Group, UCL Cancer Institute, University College London, London WC1E 6DD, UK
| | - Tomalika R Ullah
- Chromosome Maintenance Group, UCL Cancer Institute, University College London, London WC1E 6DD, UK.,MSc Human Molecular Genetics, Faculty of Medicine, Imperial College London, London SW7 2AZ, UK
| | - Shidong T Xi
- Chromosome Maintenance Group, UCL Cancer Institute, University College London, London WC1E 6DD, UK.,Faculty of Life Sciences, University College London, London WC1E 6BT, UK
| | - Jennifer Martin
- Chromosome Maintenance Group, UCL Cancer Institute, University College London, London WC1E 6DD, UK.,MSc Human Molecular Genetics, Faculty of Medicine, Imperial College London, London SW7 2AZ, UK
| | - Shaan Subramaniam
- Chromosome Maintenance Group, UCL Cancer Institute, University College London, London WC1E 6DD, UK.,Faculty of Life Sciences, University College London, London WC1E 6BT, UK
| | - Sara Marelli
- Chromosome Maintenance Group, UCL Cancer Institute, University College London, London WC1E 6DD, UK
| | - Hanna Amelina
- Chromosome Maintenance Group, UCL Cancer Institute, University College London, London WC1E 6DD, UK
| | - Kazunori Tomita
- Chromosome Maintenance Group, UCL Cancer Institute, University College London, London WC1E 6DD, UK
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8
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Escandell JM, Carvalho ES, Gallo-Fernandez M, Reis CC, Matmati S, Luís IM, Abreu IA, Coulon S, Ferreira MG. Ssu72 phosphatase is a conserved telomere replication terminator. EMBO J 2019; 38:embj.2018100476. [PMID: 30796050 PMCID: PMC6443209 DOI: 10.15252/embj.2018100476] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Revised: 01/21/2019] [Accepted: 01/28/2019] [Indexed: 01/31/2023] Open
Abstract
Telomeres, the protective ends of eukaryotic chromosomes, are replicated through concerted actions of conventional DNA polymerases and elongated by telomerase, but the regulation of this process is not fully understood. Telomere replication requires (Ctc1/Cdc13)‐Stn1‐Ten1, a telomeric ssDNA‐binding complex homologous to RPA. Here, we show that the evolutionarily conserved phosphatase Ssu72 is responsible for terminating the cycle of telomere replication in fission yeast. Ssu72 controls the recruitment of Stn1 to telomeres by regulating Stn1 phosphorylation at Ser74, a residue located within its conserved OB‐fold domain. Consequently, ssu72∆ mutants are defective in telomere replication and exhibit long 3′‐ssDNA overhangs, indicative of defective lagging‐strand DNA synthesis. We also show that hSSU72 regulates telomerase activation in human cells by controlling recruitment of hSTN1 to telomeres. These results reveal a previously unknown yet conserved role for the phosphatase SSU72, whereby this enzyme controls telomere homeostasis by activating lagging‐strand DNA synthesis, thus terminating the cycle of telomere replication.
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Affiliation(s)
| | | | | | - Clara C Reis
- Instituto Gulbenkian de Ciência, Oeiras, Portugal
| | - Samah Matmati
- Equipe Labellisée Ligue, CRCM, CNRS, Inserm, Institut Paoli-Calmettes, Aix-Marseille University, Marseille, France
| | - Inês Matias Luís
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Isabel A Abreu
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Stéphane Coulon
- Equipe Labellisée Ligue, CRCM, CNRS, Inserm, Institut Paoli-Calmettes, Aix-Marseille University, Marseille, France
| | - Miguel Godinho Ferreira
- Instituto Gulbenkian de Ciência, Oeiras, Portugal .,Institute for Research on Cancer and Aging of Nice (IRCAN), INSERM U1081 UMR7284, CNRS, Nice, France
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9
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CTC1-STN1 terminates telomerase while STN1-TEN1 enables C-strand synthesis during telomere replication in colon cancer cells. Nat Commun 2018; 9:2827. [PMID: 30026550 PMCID: PMC6053418 DOI: 10.1038/s41467-018-05154-z] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2017] [Accepted: 06/07/2018] [Indexed: 01/20/2023] Open
Abstract
Telomerase elongates the telomeric G-strand to prevent telomere shortening through conventional DNA replication. However, synthesis of the complementary C-strand by DNA polymerase α is also required to maintain telomere length. Polymerase α cannot perform this role without the ssDNA binding complex CST (CTC1-STN1-TEN1). Here we describe the roles of individual CST subunits in telomerase regulation and G-overhang maturation in human colon cancer cells. We show that CTC1-STN1 limits telomerase action to prevent G-overhang overextension. CTC1-/- cells exhibit telomeric DNA damage and growth arrest due to overhang elongation whereas TEN1-/- cells do not. However, TEN1 is essential for C-strand synthesis and TEN1-/- cells exhibit progressive telomere shortening. DNA binding analysis indicates that CTC1-STN1 retains affinity for ssDNA but TEN1 stabilizes binding. We propose CTC1-STN1 binding is sufficient to terminate telomerase action but altered DNA binding dynamics renders CTC1-STN1 unable to properly engage polymerase α on the overhang for C-strand synthesis.
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10
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Matmati S, Vaurs M, Escandell JM, Maestroni L, Nakamura TM, Ferreira MG, Géli V, Coulon S. The fission yeast Stn1-Ten1 complex limits telomerase activity via its SUMO-interacting motif and promotes telomeres replication. SCIENCE ADVANCES 2018; 4:eaar2740. [PMID: 29774234 PMCID: PMC5955624 DOI: 10.1126/sciadv.aar2740] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2017] [Accepted: 03/29/2018] [Indexed: 06/01/2023]
Abstract
Mammalian CST (CTC1-STN1-TEN1) complex fulfills numerous functions including rescue of the stalled replication forks and termination of telomerase action. In fission yeast lacking the CTC1 ortholog, the Stn1-Ten1 complex restricts telomerase action via its sumoylation-mediated interaction with Tpz1TPP1. We identify a small ubiquitin-like modifier (SUMO)-interacting motif (SIM) in the carboxyl-terminal part of Stn1 and show that this domain is crucial for SUMO and Tpz1-SUMO interactions. Point mutations in the SIM (Stn1-226) lead to telomere elongation, impair Stn1-Ten1 recruitment to telomeres, and enhance telomerase binding, revealing that Stn1 SIM domain contributes to the inhibition of telomerase activity at chromosome ends. Our results suggest that Stn1-Ten1 promotes DNA synthesis at telomeres to limit single-strand DNA accumulation. We further demonstrate that Stn1 functions in the replication of telomeric and subtelomeric regions in a Taz1-independent manner. Genetic analysis reveals that misregulation of origin firing and/or telomerase inhibition circumvents the replication defects of the stn1-226 mutant. Together, our results show that the Stn1-Ten1 complex has a dual function at telomeres by limiting telomerase action and promoting chromosome end replication.
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Affiliation(s)
- Samah Matmati
- CRCM, CNRS, INSERM, Aix-Marseille Université, Institut Paoli-Calmettes, Equipe Labellisée Ligue, 27 Boulevard Lei Roure, Marseille, France
| | - Mélina Vaurs
- CRCM, CNRS, INSERM, Aix-Marseille Université, Institut Paoli-Calmettes, Equipe Labellisée Ligue, 27 Boulevard Lei Roure, Marseille, France
| | - José M. Escandell
- Telomere and Genome Stability Laboratory, Instituto Gulbenkian de Ciência, Oeiras, Portugal
| | - Laetitia Maestroni
- CRCM, CNRS, INSERM, Aix-Marseille Université, Institut Paoli-Calmettes, Equipe Labellisée Ligue, 27 Boulevard Lei Roure, Marseille, France
| | - Toru M. Nakamura
- Department of Biochemistry and Molecular Genetics, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Miguel G. Ferreira
- Telomere and Genome Stability Laboratory, Instituto Gulbenkian de Ciência, Oeiras, Portugal
- Institute for Research on Cancer and Aging, Nice, Faculty of Medicine, CNRS UMR7284, INSERM U1081, University of Nice Sophia Antipolis, Nice, France
| | - Vincent Géli
- CRCM, CNRS, INSERM, Aix-Marseille Université, Institut Paoli-Calmettes, Equipe Labellisée Ligue, 27 Boulevard Lei Roure, Marseille, France
| | - Stéphane Coulon
- CRCM, CNRS, INSERM, Aix-Marseille Université, Institut Paoli-Calmettes, Equipe Labellisée Ligue, 27 Boulevard Lei Roure, Marseille, France
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11
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Stewart JA, Wang Y, Ackerson SM, Schuck PL. Emerging roles of CST in maintaining genome stability and human disease. Front Biosci (Landmark Ed) 2018; 23:1564-1586. [PMID: 29293451 DOI: 10.2741/4661] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The human CTC1-STN1-TEN1 (CST) complex is a single-stranded DNA binding protein that shares homology with RPA and interacts with DNA polymerase alpha/primase. CST complexes are conserved from yeasts to humans and function in telomere maintenance. A common role of CST across species is in the regulation of telomere extension by telomerase and C-strand fill-in synthesis. However, recent studies also indicate that CST promotes telomere duplex replication as well the rescue of stalled DNA replication at non-telomeric sites. Furthermore, CST dysfunction and mutation is associated with several genetic diseases and cancers. In this review, we will summarize what is known about CST with a particular focus on the emerging roles of CST in DNA replication and human disease.
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Affiliation(s)
- Jason A Stewart
- Department of Biological Sciences, University of South Carolina, Columbia, SC 29208, USA,
| | - Yilin Wang
- Department of Biological Sciences, University of South Carolina, Columbia, SC 29208, USA
| | - Stephanie M Ackerson
- Department of Biological Sciences, University of South Carolina, Columbia, SC 29208, USA
| | - Percy Logan Schuck
- Department of Biological Sciences, University of South Carolina, Columbia, SC 29208, USA
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12
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Takikawa M, Tarumoto Y, Ishikawa F. Fission yeast Stn1 is crucial for semi-conservative replication at telomeres and subtelomeres. Nucleic Acids Res 2017; 45:1255-1269. [PMID: 28180297 PMCID: PMC5388396 DOI: 10.1093/nar/gkw1176] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2016] [Revised: 11/08/2016] [Accepted: 11/23/2016] [Indexed: 12/29/2022] Open
Abstract
The CST complex is a phylogenetically conserved protein complex consisting of CTC1/Cdc13, Stn1 and Ten1 that protects telomeres on linear chromosomes. Deletion of the fission yeast homologs stn1 and ten1 results in complete telomere loss; however, the precise function of Stn1 is still largely unknown. Here, we have isolated a high-temperature sensitive stn1 allele (termed stn1-1). stn1-1 cells abruptly lost telomeric sequence almost completely at the restrictive temperature. The loss of chromosomal DNA happened without gradual telomere shortening, and extended to 30 kb from the ends of chromosomes. We found transient and modest single-stranded G-strand exposure, but did not find any evidence of checkpoint activation in stn1-1 at the restrictive temperature. When we probed neutral-neutral 2D gels for subtelomere regions, we found no Y-arc-shaped replication intermediates in cycling cells. We conclude that the loss of telomere and subtelomere DNAs in stn1-1 cells at the restrictive temperature is caused by very frequent replication fork collapses specifically in subtelomere regions. Furthermore, we identified two independent suppressor mutants of the high-temperature sensitivity of stn1-1: a multi-copy form of pmt3 and a deletion of rif1. Collectively, we propose that fission yeast Stn1 primarily safeguards the semi-conservative DNA replication at telomeres and subtelomeres.
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Affiliation(s)
- Masahiro Takikawa
- Department of Gene Mechanisms, Graduate School of Biostudies, Kyoto University, Yoshida-Konoe-cho, Sakyo-ku, Kyoto, Japan
| | - Yusuke Tarumoto
- Department of Gene Mechanisms, Graduate School of Biostudies, Kyoto University, Yoshida-Konoe-cho, Sakyo-ku, Kyoto, Japan
| | - Fuyuki Ishikawa
- Department of Gene Mechanisms, Graduate School of Biostudies, Kyoto University, Yoshida-Konoe-cho, Sakyo-ku, Kyoto, Japan
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13
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Zilio N, Eifler-Olivi K, Ulrich HD. Functions of SUMO in the Maintenance of Genome Stability. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 963:51-87. [PMID: 28197906 DOI: 10.1007/978-3-319-50044-7_4] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Like in most other areas of cellular metabolism, the functions of the ubiquitin-like modifier SUMO in the maintenance of genome stability are manifold and varied. Perturbations of global sumoylation causes a wide spectrum of phenotypes associated with defects in DNA maintenance, such as hypersensitivity to DNA-damaging agents, gross chromosomal rearrangements and loss of entire chromosomes. Consistent with these observations, many key factors involved in various DNA repair pathways have been identified as SUMO substrates. However, establishing a functional connection between a given SUMO target, the cognate SUMO ligase and a relevant phenotype has remained a challenge, mainly because of the difficulties involved in identifying important modification sites and downstream effectors that specifically recognize the target in its sumoylated state. This review will give an overview over the major pathways of DNA repair and genome maintenance influenced by the SUMO system and discuss selected examples of SUMO's actions in these pathways where the biological consequences of the modification have been elucidated.
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Affiliation(s)
- Nicola Zilio
- Institute of Molecular Biology (IMB), Ackermannweg 4, D-55128, Mainz, Germany
| | | | - Helle D Ulrich
- Institute of Molecular Biology (IMB), Ackermannweg 4, D-55128, Mainz, Germany.
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14
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Feng X, Hsu SJ, Kasbek C, Chaiken M, Price CM. CTC1-mediated C-strand fill-in is an essential step in telomere length maintenance. Nucleic Acids Res 2017; 45:4281-4293. [PMID: 28334750 PMCID: PMC5416890 DOI: 10.1093/nar/gkx125] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2016] [Accepted: 02/15/2017] [Indexed: 11/13/2022] Open
Abstract
To prevent progressive telomere shortening as a result of conventional DNA replication, new telomeric DNA must be added onto the chromosome end. The de novo DNA synthesis involves elongation of the G-rich strand of the telomere by telomerase. In human cells, the CST complex (CTC1-STN1-TEN1) also functions in telomere replication. CST first aids in duplication of the telomeric dsDNA. Then after telomerase has extended the G-rich strand, CST facilitates fill-in synthesis of the complementary C-strand. Here, we analyze telomere structure after disruption of human CTC1 and demonstrate that functional CST is essential for telomere length maintenance due to its role in mediating C-strand fill-in. Removal of CTC1 results in elongation of the 3΄ overhang on the G-rich strand. This leads to accumulation of RPA and telomeric DNA damage signaling. G-overhang length increases with time after CTC1 disruption and at early times net G-strand growth is apparent, indicating telomerase-mediated G-strand extension. In contrast, C-strand length decreases continuously, indicating a deficiency in C-strand fill-in synthesis. The lack of C-strand maintenance leads to gradual shortening of the telomeric dsDNA, similar to that observed in cells lacking telomerase. Thus, telomerase-mediated G-strand extension and CST-mediated C-strand fill-in are equally important for telomere length maintenance.
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Affiliation(s)
- Xuyang Feng
- Department of Cancer Biology, University of Cincinnati, Cincinnati, OH 45230, USA
| | - Shih-Jui Hsu
- Department of Cancer Biology, University of Cincinnati, Cincinnati, OH 45230, USA
| | - Christopher Kasbek
- Department of Cancer Biology, University of Cincinnati, Cincinnati, OH 45230, USA
| | - Mary Chaiken
- Department of Cancer Biology, University of Cincinnati, Cincinnati, OH 45230, USA
| | - Carolyn M Price
- Department of Cancer Biology, University of Cincinnati, Cincinnati, OH 45230, USA
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15
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Yalçin Z, Selenz C, Jacobs JJL. Ubiquitination and SUMOylation in Telomere Maintenance and Dysfunction. Front Genet 2017; 8:67. [PMID: 28588610 PMCID: PMC5440461 DOI: 10.3389/fgene.2017.00067] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Accepted: 05/10/2017] [Indexed: 12/14/2022] Open
Abstract
Telomeres are essential nucleoprotein structures at linear chromosomes that maintain genome integrity by protecting chromosome ends from being recognized and processed as damaged DNA. In addition, they limit the cell’s proliferative capacity, as progressive loss of telomeric DNA during successive rounds of cell division eventually causes a state of telomere dysfunction that prevents further cell division. When telomeres become critically short, the cell elicits a DNA damage response resulting in senescence, apoptosis or genomic instability, thereby impacting on aging and tumorigenesis. Over the past years substantial progress has been made in understanding the role of post-translational modifications in telomere-related processes, including telomere maintenance, replication and dysfunction. This review will focus on recent findings that establish an essential role for ubiquitination and SUMOylation at telomeres.
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Affiliation(s)
- Zeliha Yalçin
- Department of Molecular Oncology, Netherlands Cancer InstituteAmsterdam, Netherlands
| | - Carolin Selenz
- Department of Molecular Oncology, Netherlands Cancer InstituteAmsterdam, Netherlands
| | - Jacqueline J L Jacobs
- Department of Molecular Oncology, Netherlands Cancer InstituteAmsterdam, Netherlands
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16
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Nie M, Moser BA, Nakamura TM, Boddy MN. SUMO-targeted ubiquitin ligase activity can either suppress or promote genome instability, depending on the nature of the DNA lesion. PLoS Genet 2017; 13:e1006776. [PMID: 28475613 PMCID: PMC5438191 DOI: 10.1371/journal.pgen.1006776] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Revised: 05/19/2017] [Accepted: 04/24/2017] [Indexed: 11/19/2022] Open
Abstract
The posttranslational modifiers SUMO and ubiquitin critically regulate the DNA damage response (DDR). Important crosstalk between these modifiers at DNA lesions is mediated by the SUMO-targeted ubiquitin ligase (STUbL), which ubiquitinates SUMO chains to generate SUMO-ubiquitin hybrids. These SUMO-ubiquitin hybrids attract DDR proteins able to bind both modifiers, and/or are degraded at the proteasome. Despite these insights, specific roles for SUMO chains and STUbL in the DDR remain poorly defined. Notably, fission yeast defective in SUMO chain formation exhibit near wild-type resistance to genotoxins and moreover, have a greatly reduced dependency on STUbL activity for DNA repair. Based on these and other data, we propose that a critical role of STUbL is to antagonize DDR-inhibitory SUMO chain formation at DNA lesions. In this regard, we identify a SUMO-binding Swi2/Snf2 translocase called Rrp2 (ScUls1) as a mediator of the DDR defects in STUbL mutant cells. Therefore, in support of our proposal, SUMO chains attract activities that can antagonize STUbL and other DNA repair factors. Finally, we find that Taz1TRF1/TRF2-deficiency triggers extensive telomeric poly-SUMOylation. In this setting STUbL, together with its cofactor Cdc48p97, actually promotes genomic instability caused by the aberrant processing of taz1Δ telomeres by DNA repair factors. In summary, depending on the nature of the initiating DNA lesion, STUbL activity can either be beneficial or harmful. Since its discovery in 2007, SUMO-targeted ubiquitin ligase (STUbL) activity has been identified as a key regulator of diverse cellular processes such as DNA repair, mitosis and DNA replication. In each of these processes, STUbL has been shown to promote the chromatin extraction and/or degradation of SUMO chain modified proteins. However, it remains unclear whether STUbL acts as part of a "programmed" cascade to remove specific proteins, or antagonizes localized SUMO chain formation that otherwise impedes each process. Here we determine that SUMO chains, the major recruitment signal for STUbL, are largely dispensable for genotoxin resistance in fission yeast. Moreover, when SUMO chain formation is compromised, the need for STUbL activity in DNA repair is strongly reduced. These results indicate a primary role for STUbL in antagonizing localized SUMO chain formation. Interestingly, we also find that STUbL activity can be toxic at certain genomic lesions that induce extensive local SUMOylation. For example, STUbL promotes the chromosome instability and cell death caused by deprotected telomeres following Taz1TRF1/2 deletion. Together, our data suggest that STUbL limits DNA repair-inhibitory SUMO chain formation, and depending on the nature of the genomic lesion, can either suppress or cause genome instability.
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Affiliation(s)
- Minghua Nie
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, United States of America
| | - Bettina A. Moser
- Department of Biochemistry and Molecular Genetics, College of Medicine, University of Illinois at Chicago, Chicago, IL, United States of America
| | - Toru M. Nakamura
- Department of Biochemistry and Molecular Genetics, College of Medicine, University of Illinois at Chicago, Chicago, IL, United States of America
| | - Michael N. Boddy
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA, United States of America
- * E-mail:
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17
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Abstract
Telomerase is the essential reverse transcriptase required for linear chromosome maintenance in most eukaryotes. Telomerase supplements the tandem array of simple-sequence repeats at chromosome ends to compensate for the DNA erosion inherent in genome replication. The template for telomerase reverse transcriptase is within the RNA subunit of the ribonucleoprotein complex, which in cells contains additional telomerase holoenzyme proteins that assemble the active ribonucleoprotein and promote its function at telomeres. Telomerase is distinct among polymerases in its reiterative reuse of an internal template. The template is precisely defined, processively copied, and regenerated by release of single-stranded product DNA. New specificities of nucleic acid handling that underlie the catalytic cycle of repeat synthesis derive from both active site specialization and new motif elaborations in protein and RNA subunits. Studies of telomerase provide unique insights into cellular requirements for genome stability, tissue renewal, and tumorigenesis as well as new perspectives on dynamic ribonucleoprotein machines.
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Affiliation(s)
- R Alex Wu
- Department of Molecular and Cell Biology, University of California, Berkeley, California 94720-3202; , , ,
| | - Heather E Upton
- Department of Molecular and Cell Biology, University of California, Berkeley, California 94720-3202; , , ,
| | - Jacob M Vogan
- Department of Molecular and Cell Biology, University of California, Berkeley, California 94720-3202; , , ,
| | - Kathleen Collins
- Department of Molecular and Cell Biology, University of California, Berkeley, California 94720-3202; , , ,
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18
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Princz A, Tavernarakis N. The role of SUMOylation in ageing and senescent decline. Mech Ageing Dev 2017; 162:85-90. [PMID: 28088449 DOI: 10.1016/j.mad.2017.01.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Revised: 01/03/2017] [Accepted: 01/05/2017] [Indexed: 02/07/2023]
Abstract
Posttranslational protein modifications are playing crucial roles in essential cellular mechanisms. SUMOylation is a reversible posttranslational modification of specific target proteins by the attachment of a small ubiquitin-like protein. Although the mechanism of conjugation of SUMO to proteins is analogous to ubiquitination, it requires its own, specific set of enzymes. The consequences of SUMOylation are widely variable, depending on the physiological state of the cell and the attached SUMO isoform. Accumulating recent findings have revealed a prominent role of SUMOylation in molecular pathways that govern senescence and ageing. Here, we review the link between SUMO attachment events and cellular processes that influence senescence and ageing, including promyelocytic leukaemia (PML) nuclear body and telomere function, autophagy, reactive oxygen species (ROS) homeostasis and growth factor signalling.
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Affiliation(s)
- Andrea Princz
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Department of Basic Sciences, Faculty of Medicine, University of Crete, N. Plastira 100, Vassilika Vouton, Heraklion, 71110, Crete, Greece
| | - Nektarios Tavernarakis
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Department of Basic Sciences, Faculty of Medicine, University of Crete, N. Plastira 100, Vassilika Vouton, Heraklion, 71110, Crete, Greece.
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19
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Bhattacharjee A, Stewart J, Chaiken M, Price CM. STN1 OB Fold Mutation Alters DNA Binding and Affects Selective Aspects of CST Function. PLoS Genet 2016; 12:e1006342. [PMID: 27690379 PMCID: PMC5045167 DOI: 10.1371/journal.pgen.1006342] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Accepted: 09/06/2016] [Indexed: 12/03/2022] Open
Abstract
Mammalian CST (CTC1-STN1-TEN1) participates in multiple aspects of telomere replication and genome-wide recovery from replication stress. CST resembles Replication Protein A (RPA) in that it binds ssDNA and STN1 and TEN1 are structurally similar to RPA2 and RPA3. Conservation between CTC1 and RPA1 is less apparent. Currently the mechanism underlying CST action is largely unknown. Here we address CST mechanism by using a DNA-binding mutant, (STN1 OB-fold mutant, STN1-OBM) to examine the relationship between DNA binding and CST function. In vivo, STN1-OBM affects resolution of endogenous replication stress and telomere duplex replication but telomeric C-strand fill-in and new origin firing after exogenous replication stress are unaffected. These selective effects indicate mechanistic differences in CST action during resolution of different replication problems. In vitro binding studies show that STN1 directly engages both short and long ssDNA oligonucleotides, however STN1-OBM preferentially destabilizes binding to short substrates. The finding that STN1-OBM affects binding to only certain substrates starts to explain the in vivo separation of function observed in STN1-OBM expressing cells. CST is expected to engage DNA substrates of varied length and structure as it acts to resolve different replication problems. Since STN1-OBM will alter CST binding to only some of these substrates, the mutant should affect resolution of only a subset of replication problems, as was observed in the STN1-OBM cells. The in vitro studies also provide insight into CST binding mechanism. Like RPA, CST likely contacts DNA via multiple OB folds. However, the importance of STN1 for binding short substrates indicates differences in the architecture of CST and RPA DNA-protein complexes. Based on our results, we propose a dynamic DNA binding model that provides a general mechanism for CST action at diverse forms of replication stress. Mammalian CST (CTC1/STN1/TEN1) is a three protein complex that aids in several steps during telomere replication and has genome-wide roles during recovery from replication fork stalling. Loss of CST leads to abnormalities in telomere structure, genomic instability and defects in chromosome segregation. Currently, we do not understand how CST acts to ensure the resolution of very diverse types of replication problem. We set out to address this question by studying a mutant form of CST that was predicted to alter DNA binding. The mutations are in the STN1 subunit. In vivo, the STN1 mutant (STN1-OBM) affects some aspects of CST function while others are normal. The effects of STN1-OBM do not align with the telomeric versus non-telomeric roles of CST but instead separate out different aspects of CST function at telomeres and genome-wide. In vitro binding studies indicate that STN1-OBM disrupts binding to only short DNA substrates. Since CST is likely to encounter DNA substrates of varied length and structure in vivo as it helps resolve different replication problems, this finding starts to explain why STN1-OBM affects only certain aspects of CST function. Our in vitro binding studies also shed light on how CST actually binds to DNA and they suggest a novel “dynamic binding model” that provides a mechanistic explanation for how CST helps resolve a diverse array of replication problems to preserve genome stability.
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Affiliation(s)
- Anukana Bhattacharjee
- Department of Cancer Biology, University of Cincinnati, Cincinnati, Ohio, United States of America
| | - Jason Stewart
- Department of Cancer Biology, University of Cincinnati, Cincinnati, Ohio, United States of America
- Department of Biological Sciences, University of South Carolina, Columbia, South Carolina, United States of America
- * E-mail: (JS); (CMP)
| | - Mary Chaiken
- Department of Cancer Biology, University of Cincinnati, Cincinnati, Ohio, United States of America
| | - Carolyn M. Price
- Department of Cancer Biology, University of Cincinnati, Cincinnati, Ohio, United States of America
- * E-mail: (JS); (CMP)
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20
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Lee JR, Xie X, Yang K, Zhang J, Lee SY, Shippen DE. Dynamic Interactions of Arabidopsis TEN1: Stabilizing Telomeres in Response to Heat Stress. THE PLANT CELL 2016; 28:2212-2224. [PMID: 27609839 PMCID: PMC5059806 DOI: 10.1105/tpc.16.00408] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Revised: 08/25/2016] [Accepted: 09/06/2016] [Indexed: 05/15/2023]
Abstract
Telomeres are the essential nucleoprotein structures that provide a physical cap for the ends of linear chromosomes. The highly conserved CST (CTC1/STN1/TEN1) protein complex facilitates telomeric DNA replication and promotes telomere stability. Here we report three unexpected properties of Arabidopsis thaliana TEN1 that indicate it possesses functions distinct from other previously characterized telomere proteins. First, we show that telomeres in ten1 mutants are highly sensitive to thermal stress. Heat shock causes abrupt and dramatic loss of telomeric DNA in ten1 plants, likely via deletional recombination. Second, we show that AtTEN1 has the properties of a heat-shock induced molecular chaperone. At elevated temperature, AtTEN1 rapidly assembles into high molecular weight homo-oligomeric complexes that efficiently suppress heat-induced aggregation of model protein substrates in vitro. Finally, we report that AtTEN1 specifically protects CTC1 from heat-induced aggregation in vitro, and from heat-induced protein degradation and loss of telomere association in vivo. Collectively, these observations define Arabidopsis TEN1 as a highly dynamic protein that works in concert with CTC1 to preserve telomere integrity in response to environmental stress.
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Affiliation(s)
- Jung Ro Lee
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843-2128
| | - Xiaoyuan Xie
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843-2128
| | - Kailu Yang
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843-2128
| | - Junjie Zhang
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843-2128
| | - Sang Yeol Lee
- Division of Applied Life Sciences (BK21) and PMBBRC, Gyeongsang National University, Jinju 52828, Republic of Korea
| | - Dorothy E Shippen
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843-2128
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21
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Kim YJ, Kim ET, Kim YE, Lee MK, Kwon KM, Kim KI, Stamminger T, Ahn JH. Consecutive Inhibition of ISG15 Expression and ISGylation by Cytomegalovirus Regulators. PLoS Pathog 2016; 12:e1005850. [PMID: 27564865 PMCID: PMC5001722 DOI: 10.1371/journal.ppat.1005850] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Accepted: 08/08/2016] [Indexed: 11/18/2022] Open
Abstract
Interferon-stimulated gene 15 (ISG15) encodes an ubiquitin-like protein that covalently conjugates protein. Protein modification by ISG15 (ISGylation) is known to inhibit the replication of many viruses. However, studies on the viral targets and viral strategies to regulate ISGylation-mediated antiviral responses are limited. In this study, we show that human cytomegalovirus (HCMV) replication is inhibited by ISGylation, but the virus has evolved multiple countermeasures. HCMV-induced ISG15 expression was mitigated by IE1, a viral inhibitor of interferon signaling, however, ISGylation was still strongly upregulated during virus infection. RNA interference of UBE1L (E1), UbcH8 (E2), Herc5 (E3), and UBP43 (ISG15 protease) revealed that ISGylation inhibits HCMV growth by downregulating viral gene expression and virion release in a manner that is more prominent at low multiplicity of infection. A viral regulator pUL26 was found to interact with ISG15, UBE1L, and Herc5, and be ISGylated. ISGylation of pUL26 regulated its stability and inhibited its activities to suppress NF-κB signaling and complement the growth of UL26-null mutant virus. Moreover, pUL26 reciprocally suppressed virus-induced ISGylation independent of its own ISGylation. Consistently, ISGylation was more pronounced in infections with the UL26-deleted mutant virus, whose growth was more sensitive to IFNβ treatment than that of the wild-type virus. Therefore, pUL26 is a viral ISG15 target that also counteracts ISGylation. Our results demonstrate that ISGylation inhibits HCMV growth at multiple steps and that HCMV has evolved countermeasures to suppress ISG15 transcription and protein ISGylation, highlighting the importance of the interplay between virus and ISGylation in productive viral infection. Type I IFN response is a front-line defense against virus infection. Activation of type I IFN signaling leads to expression of a subset of cellular proteins encoded by interferon-stimulated genes (ISGs). ISG15 encodes an ubiquitin-like protein that is covalently conjugated to protein lysine residues. ISG15 modification (ISGylation) of a protein causes changes of protein function. ISGylation is known to inhibit the replication of many viruses, although pro-viral effects of ISGylation are also reported. Given that ISG15 and the enzymes involved in ISGylation are strongly induced upon virus infection, understanding the interplay between virus and ISGylation is an important issue in virus-host interaction. Nevertheless, viral substrates of ISG15 and viral strategies to regulate ISGylation-mediated antiviral responses are limited to only a few examples. In this study we demonstrate that ISGylation suppresses human cytomegalovirus (HCMV) infection but the virus is armed with countermeasures that consecutively reduce ISG15 transcription and protein ISGylation. Interestingly, a viral ISG15 target is found to inhibit ISGylation. This study highlights that ISGylation is a critical innate immune response against HCMV infection and interfering with ISG15-mediated anti-viral immunity is critical for productive viral infection.
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Affiliation(s)
- Ye Ji Kim
- Department of Molecular Cell Biology, Samsung Biomedical Research Institute, Sungkyunkwan University School of Medicine, Suwon, Republic of Korea
| | - Eui Tae Kim
- Department of Molecular Cell Biology, Samsung Biomedical Research Institute, Sungkyunkwan University School of Medicine, Suwon, Republic of Korea
| | - Young-Eui Kim
- Department of Molecular Cell Biology, Samsung Biomedical Research Institute, Sungkyunkwan University School of Medicine, Suwon, Republic of Korea
| | - Myoung Kyu Lee
- Department of Molecular Cell Biology, Samsung Biomedical Research Institute, Sungkyunkwan University School of Medicine, Suwon, Republic of Korea
| | - Ki Mun Kwon
- Department of Molecular Cell Biology, Samsung Biomedical Research Institute, Sungkyunkwan University School of Medicine, Suwon, Republic of Korea
| | - Keun Il Kim
- Department of Biological Sciences, Sookmyung Women's University, Seoul, Republic of Korea
| | - Thomas Stamminger
- Institute for Clinical and Molecular Virology, University of Erlangen-Nuremberg, Schlossgarten, Erlangen, Germany
| | - Jin-Hyun Ahn
- Department of Molecular Cell Biology, Samsung Biomedical Research Institute, Sungkyunkwan University School of Medicine, Suwon, Republic of Korea
- * E-mail:
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22
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Køhler JB, Tammsalu T, Jørgensen MM, Steen N, Hay RT, Thon G. Targeting of SUMO substrates to a Cdc48-Ufd1-Npl4 segregase and STUbL pathway in fission yeast. Nat Commun 2015; 6:8827. [PMID: 26537787 PMCID: PMC4667616 DOI: 10.1038/ncomms9827] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2015] [Accepted: 10/08/2015] [Indexed: 12/26/2022] Open
Abstract
In eukaryotes, the conjugation of proteins to the small ubiquitin-like modifier (SUMO) regulates numerous cellular functions. A proportion of SUMO conjugates are targeted for degradation by SUMO-targeted ubiquitin ligases (STUbLs) and it has been proposed that the ubiquitin-selective chaperone Cdc48/p97-Ufd1-Npl4 facilitates this process. However, the extent to which the two pathways overlap, and how substrates are selected, remains unknown. Here we address these questions in fission yeast through proteome-wide analyses of SUMO modification sites. We identify over a thousand sumoylated lysines in a total of 468 proteins and quantify changes occurring in the SUMO modification status when the STUbL or Ufd1 pathways are compromised by mutations. The data suggest the coordinated processing of several classes of SUMO conjugates, many dynamically associated with centromeres or telomeres. They provide new insights into subnuclear organization and chromosome biology, and, altogether, constitute an extensive resource for the molecular characterization of SUMO function and dynamics.
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Affiliation(s)
- Julie Bonne Køhler
- Department of Biology, University of Copenhagen, Ole Maaløes vej 5, Copenhagen DK-2200, Denmark
| | - Triin Tammsalu
- Centre for Gene Regulation and Expression, Sir James Black Centre, College of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, UK
| | - Maria Mønster Jørgensen
- Department of Biology, University of Copenhagen, Ole Maaløes vej 5, Copenhagen DK-2200, Denmark
| | - Nana Steen
- Department of Biology, University of Copenhagen, Ole Maaløes vej 5, Copenhagen DK-2200, Denmark
| | - Ronald Thomas Hay
- Centre for Gene Regulation and Expression, Sir James Black Centre, College of Life Sciences, University of Dundee, Dow Street, Dundee DD1 5EH, UK
| | - Geneviève Thon
- Department of Biology, University of Copenhagen, Ole Maaløes vej 5, Copenhagen DK-2200, Denmark
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High Confidence Fission Yeast SUMO Conjugates Identified by Tandem Denaturing Affinity Purification. Sci Rep 2015; 5:14389. [PMID: 26404184 PMCID: PMC4585906 DOI: 10.1038/srep14389] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2015] [Accepted: 08/27/2015] [Indexed: 01/01/2023] Open
Abstract
Covalent attachment of the small ubiquitin-like modifier (SUMO) to key targets in the proteome critically regulates the evolutionarily conserved processes of cell cycle control, transcription, DNA replication and maintenance of genome stability. The proteome-wide identification of SUMO conjugates in budding yeast has been invaluable in helping to define roles of SUMO in these processes. Like budding yeast, fission yeast is an important and popular model organism; however, the fission yeast Schizosaccharomyces pombe community currently lacks proteome-wide knowledge of SUMO pathway targets. To begin to address this deficiency, we adapted and used a highly stringent Tandem Denaturing Affinity Purification (TDAP) method, coupled with mass spectrometry, to identify fission yeast SUMO conjugates. Comparison of our data with that compiled in budding yeast reveals conservation of SUMO target enrichment in nuclear and chromatin-associated processes. Moreover, the SUMO "cloud" phenomenon, whereby multiple components of a single protein complex are SUMOylated, is also conserved. Overall, SUMO TDAP provides both a key resource of high confidence SUMO-modified target proteins in fission yeast, and a robust method for future analyses of SUMO function.
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Narayanan S, Dubarry M, Lawless C, Banks AP, Wilkinson DJ, Whitehall SK, Lydall D. Quantitative Fitness Analysis Identifies exo1∆ and Other Suppressors or Enhancers of Telomere Defects in Schizosaccharomyces pombe. PLoS One 2015; 10:e0132240. [PMID: 26168240 PMCID: PMC4500466 DOI: 10.1371/journal.pone.0132240] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Accepted: 06/11/2015] [Indexed: 01/28/2023] Open
Abstract
Synthetic genetic array (SGA) has been successfully used to identify genetic interactions in S. cerevisiae and S. pombe. In S. pombe, SGA methods use either cycloheximide (C) or heat shock (HS) to select double mutants before measuring colony size as a surrogate for fitness. Quantitative Fitness Analysis (QFA) is a different method for determining fitness of microbial strains. In QFA, liquid cultures are spotted onto solid agar and growth curves determined for each spot by photography and model fitting. Here, we compared the two S. pombe SGA methods and found that the HS method was more reproducible for us. We also developed a QFA procedure for S. pombe. We used QFA to identify genetic interactions affecting two temperature sensitive, telomere associated query mutations (taz1Δ and pot1-1). We identify exo1∆ and other gene deletions as suppressors or enhancers of S. pombe telomere defects. Our study identifies known and novel gene deletions affecting the fitness of strains with telomere defects. The interactions we identify may be relevant in human cells.
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Affiliation(s)
- Siddharth Narayanan
- Institute for Cell & Molecular Biosciences, Newcastle University Medical School, Newcastle upon Tyne, NE2 4HH, United Kingdom
| | - Marion Dubarry
- Institute for Cell & Molecular Biosciences, Newcastle University Medical School, Newcastle upon Tyne, NE2 4HH, United Kingdom
| | - Conor Lawless
- Institute for Cell & Molecular Biosciences, Newcastle University Medical School, Newcastle upon Tyne, NE2 4HH, United Kingdom
| | - A. Peter Banks
- High Throughput Screening Facility, Newcastle Biomedicine, Newcastle University, Newcastle upon Tyne, NE2 4HH, United Kingdom
| | - Darren J. Wilkinson
- School of Mathematics & Statistics, Newcastle University, Newcastle upon Tyne, NE1 7RU, United Kingdom
| | - Simon K. Whitehall
- Institute for Cell & Molecular Biosciences, Newcastle University Medical School, Newcastle upon Tyne, NE2 4HH, United Kingdom
| | - David Lydall
- Institute for Cell & Molecular Biosciences, Newcastle University Medical School, Newcastle upon Tyne, NE2 4HH, United Kingdom
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25
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Audry J, Maestroni L, Delagoutte E, Gauthier T, Nakamura TM, Gachet Y, Saintomé C, Géli V, Coulon S. RPA prevents G-rich structure formation at lagging-strand telomeres to allow maintenance of chromosome ends. EMBO J 2015; 34:1942-58. [PMID: 26041456 DOI: 10.15252/embj.201490773] [Citation(s) in RCA: 75] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2014] [Accepted: 05/06/2015] [Indexed: 01/07/2023] Open
Abstract
Replication protein A (RPA) is a highly conserved heterotrimeric single-stranded DNA-binding protein involved in DNA replication, recombination, and repair. In fission yeast, the Rpa1-D223Y mutation provokes telomere shortening. Here, we show that this mutation impairs lagging-strand telomere replication and leads to the accumulation of secondary structures and recruitment of the homologous recombination factor Rad52. The presence of these secondary DNA structures correlates with reduced association of shelterin subunits Pot1 and Ccq1 at telomeres. Strikingly, heterologous expression of the budding yeast Pif1 known to efficiently unwind G-quadruplex rescues all the telomeric defects of the D223Y cells. Furthermore, in vitro data show that the identical D to Y mutation in human RPA specifically affects its ability to bind G-quadruplex. We propose that RPA prevents the formation of G-quadruplex structures at lagging-strand telomeres to promote shelterin association and facilitate telomerase action at telomeres.
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Affiliation(s)
- Julien Audry
- Cancer Research Center of Marseille (CRCM), U1068 Inserm, UMR7258 CNRS, Institut Paoli-Calmettes, Aix Marseille University (AMU), Marseille, France Ligue Nationale contre le Cancer (LNCC) (Equipe Labellisée), Paris, France
| | - Laetitia Maestroni
- Cancer Research Center of Marseille (CRCM), U1068 Inserm, UMR7258 CNRS, Institut Paoli-Calmettes, Aix Marseille University (AMU), Marseille, France Ligue Nationale contre le Cancer (LNCC) (Equipe Labellisée), Paris, France
| | - Emmanuelle Delagoutte
- Structure des Acides Nucléiques, Télomères et Evolution, Inserm U1154, CNRS UMR 7196, Muséum National d'Histoire Naturelle, Paris Cedex 05, France
| | - Tiphaine Gauthier
- Laboratoire de Biologie Cellulaire et Moléculaire du Controle de la Prolifération UMR5088, Université de Toulouse, Toulouse, France
| | - Toru M Nakamura
- Department of Biochemistry and Molecular Genetics, University of Illinois at Chicago, Chicago, IL, USA
| | - Yannick Gachet
- Laboratoire de Biologie Cellulaire et Moléculaire du Controle de la Prolifération UMR5088, Université de Toulouse, Toulouse, France
| | - Carole Saintomé
- Structure des Acides Nucléiques, Télomères et Evolution, Inserm U1154, CNRS UMR 7196, Muséum National d'Histoire Naturelle, Paris Cedex 05, France UPMC Univ Paris 06, UFR927, Sorbonne Universités, Paris, France
| | - Vincent Géli
- Cancer Research Center of Marseille (CRCM), U1068 Inserm, UMR7258 CNRS, Institut Paoli-Calmettes, Aix Marseille University (AMU), Marseille, France Ligue Nationale contre le Cancer (LNCC) (Equipe Labellisée), Paris, France
| | - Stéphane Coulon
- Cancer Research Center of Marseille (CRCM), U1068 Inserm, UMR7258 CNRS, Institut Paoli-Calmettes, Aix Marseille University (AMU), Marseille, France Ligue Nationale contre le Cancer (LNCC) (Equipe Labellisée), Paris, France
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26
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Sarangi P, Zhao X. SUMO-mediated regulation of DNA damage repair and responses. Trends Biochem Sci 2015; 40:233-42. [PMID: 25778614 DOI: 10.1016/j.tibs.2015.02.006] [Citation(s) in RCA: 104] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Revised: 02/17/2015] [Accepted: 02/17/2015] [Indexed: 12/21/2022]
Abstract
Sumoylation has important roles during DNA damage repair and responses. Recent broad-scope and substrate-based studies have shed light on the regulation and significance of sumoylation during these processes. An emerging paradigm is that sumoylation of many DNA metabolism proteins is controlled by DNA engagement. Such 'on-site modification' can explain low substrate modification levels and has important implications in sumoylation mechanisms and effects. New studies also suggest that sumoylation can regulate a process through an ensemble effect or via major substrates. Additionally, we describe new trends in the functional effects of sumoylation, such as bi-directional changes in biomolecule binding and multilevel coordination with other modifications. These emerging themes and models will stimulate our thinking and research in sumoylation and genome maintenance.
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Affiliation(s)
- Prabha Sarangi
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA; Programs in Biochemistry, Cell, and Molecular Biology, Weill Graduate School of Medical Sciences of Cornell University, New York, NY 10021, USA
| | - Xiaolan Zhao
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA.
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27
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Renfrew KB, Song X, Lee JR, Arora A, Shippen DE. POT1a and components of CST engage telomerase and regulate its activity in Arabidopsis. PLoS Genet 2014; 10:e1004738. [PMID: 25329641 PMCID: PMC4199523 DOI: 10.1371/journal.pgen.1004738] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2014] [Accepted: 09/06/2014] [Indexed: 11/18/2022] Open
Abstract
Protection of Telomeres 1 (POT1) is a conserved nucleic acid binding protein implicated in both telomere replication and chromosome end protection. We previously showed that Arabidopsis thaliana POT1a associates with the TER1 telomerase RNP, and is required for telomere length maintenance in vivo. Here we further dissect the function of POT1a and explore its interplay with the CST (CTC1/STN1/TEN1) telomere complex. Analysis of pot1a null mutants revealed that POT1a is not required for telomerase recruitment to telomeres, but is required for telomerase to maintain telomere tracts. We show that POT1a stimulates the synthesis of long telomere repeat arrays by telomerase, likely by enhancing repeat addition processivity. We demonstrate that POT1a binds STN1 and CTC1 in vitro, and further STN1 and CTC1, like POT1a, associate with enzymatically active telomerase in vivo. Unexpectedly, the in vitro interaction of STN1 with TEN1 and POT1a was mutually exclusive, indicating that POT1a and TEN1 may compete for the same binding site on STN1 in vivo. Finally, unlike CTC1 and STN1, TEN1 was not associated with active telomerase in vivo, consistent with our previous data showing that TEN1 negatively regulates telomerase enzyme activity. Altogether, our data support a two-state model in which POT1a promotes an extendable telomere state via contacts with the telomerase RNP as well as STN1 and CTC1, while TEN1 opposes these functions.
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Affiliation(s)
- Kyle B. Renfrew
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, United States of America
| | - Xiangyu Song
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, United States of America
| | - Jung Ro Lee
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, United States of America
| | - Amit Arora
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, United States of America
| | - Dorothy E. Shippen
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas, United States of America
- * E-mail:
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