1
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Al-Turki TM, Maranon DG, Nelson CB, Lewis AM, Luxton JJ, Taylor LE, Altina N, Wu F, Du H, Kim J, Damle N, Overbey E, Meydan C, Grigorev K, Winer DA, Furman D, Mason CE, Bailey SM. Telomeric RNA (TERRA) increases in response to spaceflight and high-altitude climbing. Commun Biol 2024; 7:698. [PMID: 38862827 PMCID: PMC11167063 DOI: 10.1038/s42003-024-06014-x] [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: 12/03/2023] [Accepted: 03/06/2024] [Indexed: 06/13/2024] Open
Abstract
Telomeres are repetitive nucleoprotein complexes at chromosomal termini essential for maintaining genome stability. Telomeric RNA, or TERRA, is a previously presumed long noncoding RNA of heterogeneous lengths that contributes to end-capping structure and function, and facilitates telomeric recombination in tumors that maintain telomere length via the telomerase-independent Alternative Lengthening of Telomeres (ALT) pathway. Here, we investigated TERRA in the radiation-induced DNA damage response (DDR) across astronauts, high-altitude climbers, healthy donors, and cellular models. Similar to astronauts in the space radiation environment and climbers of Mt. Everest, in vitro radiation exposure prompted increased transcription of TERRA, while simulated microgravity did not. Data suggest a specific TERRA DDR to telomeric double-strand breaks (DSBs), and provide direct demonstration of hybridized TERRA at telomere-specific DSB sites, indicative of protective TERRA:telomeric DNA hybrid formation. Targeted telomeric DSBs also resulted in accumulation of TERRA foci in G2-phase, supportive of TERRA's role in facilitating recombination-mediated telomere elongation. Results have important implications for scenarios involving persistent telomeric DNA damage, such as those associated with chronic oxidative stress (e.g., aging, systemic inflammation, environmental and occupational radiation exposures), which can trigger transient ALT in normal human cells, as well as for targeting TERRA as a therapeutic strategy against ALT-positive tumors.
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Affiliation(s)
- Taghreed M Al-Turki
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, CO, USA
- Cell and Molecular Biology Program, Colorado State University, Fort Collins, CO, USA
- Lineberger Comprehensive Cancer Center and Departments of Microbiology and Immunology, and Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - David G Maranon
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, CO, USA
- Department of Microbiology, Immunology, and Pathology, Colorado State University, Fort Collins, CO, USA
| | - Christopher B Nelson
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, CO, USA
- Cell and Molecular Biology Program, Colorado State University, Fort Collins, CO, USA
- Children's Medical Research Institute, 214 Hawkesbury Road, Westmead, Sydney, NSW, 2145, Australia
| | - Aidan M Lewis
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, CO, USA
- Cell and Molecular Biology Program, Colorado State University, Fort Collins, CO, USA
| | - Jared J Luxton
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, CO, USA
- Cell and Molecular Biology Program, Colorado State University, Fort Collins, CO, USA
| | - Lynn E Taylor
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, CO, USA
| | - Noelia Altina
- Cell and Molecular Biology Program, Colorado State University, Fort Collins, CO, USA
- Department of Microbiology, Immunology, and Pathology, Colorado State University, Fort Collins, CO, USA
| | - Fei Wu
- Buck AI Platform, Buck Institute for Research on Aging, Novato, CA, USA
| | - Huixun Du
- Buck AI Platform, Buck Institute for Research on Aging, Novato, CA, USA
| | - JangKeun Kim
- Department of Physiology and Biophysics, Weill Cornell Medicine, New York, NY, USA
- The HRH Prince Alwaleed Bin Talal Bin Abdulaziz Alsaud Institute for Computational Biomedicine and WorldQuant Initiative for Quantitative Prediction, Weill Cornell Medicine, New York, NY, USA
| | - Namita Damle
- Department of Physiology and Biophysics, Weill Cornell Medicine, New York, NY, USA
- The HRH Prince Alwaleed Bin Talal Bin Abdulaziz Alsaud Institute for Computational Biomedicine and WorldQuant Initiative for Quantitative Prediction, Weill Cornell Medicine, New York, NY, USA
| | - Eliah Overbey
- Department of Physiology and Biophysics, Weill Cornell Medicine, New York, NY, USA
- The HRH Prince Alwaleed Bin Talal Bin Abdulaziz Alsaud Institute for Computational Biomedicine and WorldQuant Initiative for Quantitative Prediction, Weill Cornell Medicine, New York, NY, USA
| | - Cem Meydan
- Department of Physiology and Biophysics, Weill Cornell Medicine, New York, NY, USA
- The HRH Prince Alwaleed Bin Talal Bin Abdulaziz Alsaud Institute for Computational Biomedicine and WorldQuant Initiative for Quantitative Prediction, Weill Cornell Medicine, New York, NY, USA
| | - Kirill Grigorev
- Department of Physiology and Biophysics, Weill Cornell Medicine, New York, NY, USA
- The HRH Prince Alwaleed Bin Talal Bin Abdulaziz Alsaud Institute for Computational Biomedicine and WorldQuant Initiative for Quantitative Prediction, Weill Cornell Medicine, New York, NY, USA
| | - Daniel A Winer
- Buck AI Platform, Buck Institute for Research on Aging, Novato, CA, USA
| | - David Furman
- Buck AI Platform, Buck Institute for Research on Aging, Novato, CA, USA
- Stanford 1000 Immunomes Project, Stanford School of Medicine, Stanford, CA, USA
- Instituto de Investigaciones en Medicina Traslacional (IIMT), Universidad Austral, CONICET, Pilar, Argentina
| | - Christopher E Mason
- Department of Physiology and Biophysics, Weill Cornell Medicine, New York, NY, USA.
- The HRH Prince Alwaleed Bin Talal Bin Abdulaziz Alsaud Institute for Computational Biomedicine and WorldQuant Initiative for Quantitative Prediction, Weill Cornell Medicine, New York, NY, USA.
| | - Susan M Bailey
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, CO, USA.
- Cell and Molecular Biology Program, Colorado State University, Fort Collins, CO, USA.
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2
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Gu L, Liu M, Zhang Y, Zhou H, Wang Y, Xu ZX. Telomere-related DNA damage response pathways in cancer therapy: prospective targets. Front Pharmacol 2024; 15:1379166. [PMID: 38910895 PMCID: PMC11190371 DOI: 10.3389/fphar.2024.1379166] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2024] [Accepted: 05/23/2024] [Indexed: 06/25/2024] Open
Abstract
Maintaining the structural integrity of genomic chromosomal DNA is an essential role of cellular life and requires two important biological mechanisms: the DNA damage response (DDR) mechanism and telomere protection mechanism at chromosome ends. Because abnormalities in telomeres and cellular DDR regulation are strongly associated with human aging and cancer, there is a reciprocal regulation of telomeres and cellular DDR. Moreover, several drug treatments for DDR are currently available. This paper reviews the progress in research on the interaction between telomeres and cellular DNA damage repair pathways. The research on the crosstalk between telomere damage and DDR is important for improving the efficacy of tumor treatment. However, further studies are required to confirm this hypothesis.
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Affiliation(s)
- Liting Gu
- Key Laboratory of Pathobiology, Ministry of Education, Jilin University, Changchun, Jilin, China
| | - Mingdi Liu
- Key Laboratory of Pathobiology, Ministry of Education, Jilin University, Changchun, Jilin, China
| | - Yuning Zhang
- Key Laboratory of Pathobiology, Ministry of Education, Jilin University, Changchun, Jilin, China
| | - Honglan Zhou
- Department of Urology, The First Hospital of Jilin University, Changchun, Jilin, China
| | - Yishu Wang
- Key Laboratory of Pathobiology, Ministry of Education, Jilin University, Changchun, Jilin, China
| | - Zhi-Xiang Xu
- Key Laboratory of Pathobiology, Ministry of Education, Jilin University, Changchun, Jilin, China
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3
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Otarbayev D, Myung K. Exploring factors influencing choice of DNA double-strand break repair pathways. DNA Repair (Amst) 2024; 140:103696. [PMID: 38820807 DOI: 10.1016/j.dnarep.2024.103696] [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: 04/17/2024] [Revised: 05/20/2024] [Accepted: 05/20/2024] [Indexed: 06/02/2024]
Abstract
DNA double-strand breaks (DSBs) represent one of the most severe threats to genomic integrity, demanding intricate repair mechanisms within eukaryotic cells. A diverse array of factors orchestrates the complex choreography of DSB signaling and repair, encompassing repair pathways, such as non-homologous end-joining, homologous recombination, and polymerase-θ-mediated end-joining. This review looks into the intricate decision-making processes guiding eukaryotic cells towards a particular repair pathway, particularly emphasizing the processing of two-ended DSBs. Furthermore, we elucidate the transformative role of Cas9, a site-specific endonuclease, in revolutionizing our comprehension of DNA DSB repair dynamics. Additionally, we explore the burgeoning potential of Cas9's remarkable ability to induce sequence-specific DSBs, offering a promising avenue for precise targeting of tumor cells. Through this comprehensive exploration, we unravel the intricate molecular mechanisms of cellular responses to DSBs, shedding light on both fundamental repair processes and cutting-edge therapeutic strategies.
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Affiliation(s)
- Daniyar Otarbayev
- Center for Genomic Integrity, Institute for Basic Science, Ulsan 44919, South Korea; Department of Biomedical Engineering, Ulsan National Institute of Science and Technology, Ulsan 44919, South Korea
| | - Kyungjae Myung
- Center for Genomic Integrity, Institute for Basic Science, Ulsan 44919, South Korea; Department of Biomedical Engineering, Ulsan National Institute of Science and Technology, Ulsan 44919, South Korea.
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4
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Sonmez C, Toia B, Eickhoff P, Matei AM, El Beyrouthy M, Wallner B, Douglas ME, de Lange T, Lottersberger F. DNA-PK controls Apollo's access to leading-end telomeres. Nucleic Acids Res 2024; 52:4313-4327. [PMID: 38407308 PMCID: PMC11077071 DOI: 10.1093/nar/gkae105] [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: 05/19/2023] [Revised: 01/23/2024] [Accepted: 02/01/2024] [Indexed: 02/27/2024] Open
Abstract
The complex formed by Ku70/80 and DNA-PKcs (DNA-PK) promotes the synapsis and the joining of double strand breaks (DSBs) during canonical non-homologous end joining (c-NHEJ). In c-NHEJ during V(D)J recombination, DNA-PK promotes the processing of the ends and the opening of the DNA hairpins by recruiting and/or activating the nuclease Artemis/DCLRE1C/SNM1C. Paradoxically, DNA-PK is also required to prevent the fusions of newly replicated leading-end telomeres. Here, we describe the role for DNA-PK in controlling Apollo/DCLRE1B/SNM1B, the nuclease that resects leading-end telomeres. We show that the telomeric function of Apollo requires DNA-PKcs's kinase activity and the binding of Apollo to DNA-PK. Furthermore, AlphaFold-Multimer predicts that Apollo's nuclease domain has extensive additional interactions with DNA-PKcs, and comparison to the cryo-EM structure of Artemis bound to DNA-PK phosphorylated on the ABCDE/Thr2609 cluster suggests that DNA-PK can similarly grant Apollo access to the DNA end. In agreement, the telomeric function of DNA-PK requires the ABCDE/Thr2609 cluster. These data reveal that resection of leading-end telomeres is regulated by DNA-PK through its binding to Apollo and its (auto)phosphorylation-dependent positioning of Apollo at the DNA end, analogous but not identical to DNA-PK dependent regulation of Artemis at hairpins.
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Affiliation(s)
- Ceylan Sonmez
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping 58 183, Sweden
| | - Beatrice Toia
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping 58 183, Sweden
| | - Patrik Eickhoff
- Chester Beatty Laboratories, The Institute of Cancer Research, 237 Fulham Road, London SW3 6JB, UK
| | - Andreea Medeea Matei
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping 58 183, Sweden
| | - Michael El Beyrouthy
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping 58 183, Sweden
| | - Björn Wallner
- Department of Physics, Chemistry and Biology, Linköping University, Linköping 58 183, Sweden
| | - Max E Douglas
- Chester Beatty Laboratories, The Institute of Cancer Research, 237 Fulham Road, London SW3 6JB, UK
| | - Titia de Lange
- Laboratory for Cell Biology and Genetics, The Rockefeller University, 1230 York Avenue, NY, NY 10021, USA
| | - Francisca Lottersberger
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping 58 183, Sweden
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5
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Wondisford AR, Lee J, Lu R, Schuller M, Groslambert J, Bhargava R, Schamus-Haynes S, Cespedes LC, Opresko PL, Pickett HA, Min J, Ahel I, O'Sullivan RJ. Deregulated DNA ADP-ribosylation impairs telomere replication. Nat Struct Mol Biol 2024; 31:791-800. [PMID: 38714889 PMCID: PMC11102865 DOI: 10.1038/s41594-024-01279-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2023] [Accepted: 03/18/2024] [Indexed: 05/21/2024]
Abstract
The recognition that DNA can be ADP ribosylated provides an unexpected regulatory level of how ADP-ribosylation contributes to genome stability, epigenetics and immunity. Yet, it remains unknown whether DNA ADP-ribosylation (DNA-ADPr) promotes genome stability and how it is regulated. Here, we show that telomeres are subject to DNA-ADPr catalyzed by PARP1 and removed by TARG1. Mechanistically, we show that DNA-ADPr is coupled to lagging telomere DNA strand synthesis, forming at single-stranded DNA present at unligated Okazaki fragments and on the 3' single-stranded telomere overhang. Persistent DNA-linked ADPr, due to TARG1 deficiency, eventually leads to telomere shortening. Furthermore, using the bacterial DNA ADP-ribosyl-transferase toxin to modify DNA at telomeres directly, we demonstrate that unhydrolyzed DNA-linked ADP-ribose compromises telomere replication and telomere integrity. Thus, by identifying telomeres as chromosomal targets of PARP1 and TARG1-regulated DNA-ADPr, whose deregulation compromises telomere replication and integrity, our study highlights and establishes the critical importance of controlling DNA-ADPr turnover for sustained genome stability.
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Affiliation(s)
- Anne R Wondisford
- Department of Pharmacology and Chemical Biology, UPMC Hillman Cancer Center, University of Pittsburgh, Pittsburgh, PA, USA
| | - Junyeop Lee
- Institute for Cancer Genetics, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, USA
| | - Robert Lu
- Telomere Length Regulation Unit, Children's Medical Research Institute, Faculty of Medicine and Health, University of Sydney, Westmead, New South Wales, Australia
| | - Marion Schuller
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
| | | | - Ragini Bhargava
- Department of Pharmacology and Chemical Biology, UPMC Hillman Cancer Center, University of Pittsburgh, Pittsburgh, PA, USA
| | - Sandra Schamus-Haynes
- Department of Pharmacology and Chemical Biology, UPMC Hillman Cancer Center, University of Pittsburgh, Pittsburgh, PA, USA
| | - Leyneir C Cespedes
- Institute for Cancer Genetics, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, USA
| | - Patricia L Opresko
- Department of Pharmacology and Chemical Biology, UPMC Hillman Cancer Center, University of Pittsburgh, Pittsburgh, PA, USA
- Department of Environmental and Occupational Health, University of Pittsburgh, Pittsburgh, PA, USA
| | - Hilda A Pickett
- Telomere Length Regulation Unit, Children's Medical Research Institute, Faculty of Medicine and Health, University of Sydney, Westmead, New South Wales, Australia
| | - Jaewon Min
- Institute for Cancer Genetics, Columbia University Vagelos College of Physicians and Surgeons, New York, NY, USA
| | - Ivan Ahel
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
| | - Roderick J O'Sullivan
- Department of Pharmacology and Chemical Biology, UPMC Hillman Cancer Center, University of Pittsburgh, Pittsburgh, PA, USA.
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6
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Muoio D, Laspata N, Dannenberg RL, Curry C, Darkoa-Larbi S, Hedglin M, Uttam S, Fouquerel E. PARP2 promotes Break Induced Replication-mediated telomere fragility in response to replication stress. Nat Commun 2024; 15:2857. [PMID: 38565848 PMCID: PMC10987537 DOI: 10.1038/s41467-024-47222-7] [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: 05/30/2023] [Accepted: 03/22/2024] [Indexed: 04/04/2024] Open
Abstract
PARP2 is a DNA-dependent ADP-ribosyl transferase (ARTs) enzyme with Poly(ADP-ribosyl)ation activity that is triggered by DNA breaks. It plays a role in the Base Excision Repair pathway, where it has overlapping functions with PARP1. However, additional roles for PARP2 have emerged in the response of cells to replication stress. In this study, we demonstrate that PARP2 promotes replication stress-induced telomere fragility and prevents telomere loss following chronic induction of oxidative DNA lesions and BLM helicase depletion. Telomere fragility results from the activity of the break-induced replication pathway (BIR). During this process, PARP2 promotes DNA end resection, strand invasion and BIR-dependent mitotic DNA synthesis by orchestrating POLD3 recruitment and activity. Our study has identified a role for PARP2 in the response to replication stress. This finding may lead to the development of therapeutic approaches that target DNA-dependent ART enzymes, particularly in cancer cells with high levels of replication stress.
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Affiliation(s)
- Daniela Muoio
- UPMC Hillman Cancer Center, University of Pittsburgh Cancer Institute, Department of Pharmacology and Chemical Biology, Pittsburgh, PA, 15213, USA
| | - Natalie Laspata
- UPMC Hillman Cancer Center, University of Pittsburgh Cancer Institute, Department of Pharmacology and Chemical Biology, Pittsburgh, PA, 15213, USA
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, 233S. 10th street, Philadelphia, PA, 19107, USA
| | - Rachel L Dannenberg
- Department of Chemistry, The Pennsylvania State University, University park, State College, PA, 16802, USA
| | - Caroline Curry
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, 233S. 10th street, Philadelphia, PA, 19107, USA
| | - Simone Darkoa-Larbi
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, 233S. 10th street, Philadelphia, PA, 19107, USA
| | - Mark Hedglin
- Department of Chemistry, The Pennsylvania State University, University park, State College, PA, 16802, USA
| | - Shikhar Uttam
- Department of Computational and Systems Biology, UPMC Hillman Cancer Center, University of Pittsburgh, 5117 Centre Avenue, Pittsburgh, PA, 15213, USA
| | - Elise Fouquerel
- UPMC Hillman Cancer Center, University of Pittsburgh Cancer Institute, Department of Pharmacology and Chemical Biology, Pittsburgh, PA, 15213, USA.
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7
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Tire B, Talibova G, Ozturk S. The crosstalk between telomeres and DNA repair mechanisms: an overview to mammalian somatic cells, germ cells, and preimplantation embryos. J Assist Reprod Genet 2024; 41:277-291. [PMID: 38165506 PMCID: PMC10894803 DOI: 10.1007/s10815-023-03008-2] [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: 07/10/2023] [Accepted: 12/12/2023] [Indexed: 01/03/2024] Open
Abstract
Telomeres are located at the ends of linear chromosomes and play a critical role in maintaining genomic stability by preventing premature activation of DNA repair mechanisms. Because of exposure to various genotoxic agents, telomeres can undergo shortening and genetic changes. In mammalian cells, the basic DNA repair mechanisms, including base excision repair, nucleotide excision repair, double-strand break repair, and mismatch repair, function in repairing potential damages in telomeres. If these damages are not repaired correctly in time, the unfavorable results such as apoptosis, cell cycle arrest, and cancerous transition may occur. During lifespan, mammalian somatic cells, male and female germ cells, and preimplantation embryos experience a number of telomeric damages. Herein, we comprehensively reviewed the crosstalk between telomeres and the DNA repair mechanisms in the somatic cells, germ cells, and embryos. Infertility development resulting from possible defects in this crosstalk is also discussed in the light of existing studies.
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Affiliation(s)
- Betul Tire
- Department of Histology and Embryology, Akdeniz University School of Medicine, Campus, 07070, Antalya, Turkey
| | - Gunel Talibova
- Department of Histology and Embryology, Akdeniz University School of Medicine, Campus, 07070, Antalya, Turkey
| | - Saffet Ozturk
- Department of Histology and Embryology, Akdeniz University School of Medicine, Campus, 07070, Antalya, Turkey.
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8
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Lu R, Nelson CB, Rogers S, Cesare AJ, Sobinoff AP, Pickett HA. Distinct modes of telomere synthesis and extension contribute to Alternative Lengthening of Telomeres. iScience 2024; 27:108655. [PMID: 38213617 PMCID: PMC10783591 DOI: 10.1016/j.isci.2023.108655] [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: 08/07/2023] [Revised: 10/13/2023] [Accepted: 12/04/2023] [Indexed: 01/13/2024] Open
Abstract
Alternative lengthening of telomeres (ALT) is a homology-directed repair mechanism that becomes activated in a subset of cancers to maintain telomere length. One of the defining features of ALT cells is the prevalence of extrachromosomal telomeric repeat (ECTR) DNA. Here, we identify that ALT cells engage in two modes of telomere synthesis. Non-productive telomere synthesis occurs during the G2 phase of the cell cycle and is characterized by newly synthesized internal telomeric regions that are not retained in the subsequent G1, coinciding with an induction of ECTR DNA. Productive telomere synthesis occurs specifically during the transition from G2 to mitosis and is defined as the extension of the telomere termini. While many proteins associated with break-induced telomere synthesis function in both non-productive and productive telomere synthesis, POLH specifically promotes productive telomere lengthening and suppresses non-productive telomere synthesis. These findings delineate the mechanism and cell cycle regulation of ALT-mediated telomere synthesis and extension.
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Affiliation(s)
- Robert Lu
- Telomere Length Regulation Unit, Children’s Medical Research Institute, University of Sydney, Westmead, NSW, Australia
| | - Christopher B. Nelson
- Telomere Length Regulation Unit, Children’s Medical Research Institute, University of Sydney, Westmead, NSW, Australia
| | - Samuel Rogers
- Genome Integrity Unit, Children’s Medical Research Institute, University of Sydney, Westmead, NSW, Australia
| | - Anthony J. Cesare
- Genome Integrity Unit, Children’s Medical Research Institute, University of Sydney, Westmead, NSW, Australia
| | - Alexander P. Sobinoff
- Telomere Length Regulation Unit, Children’s Medical Research Institute, University of Sydney, Westmead, NSW, Australia
| | - Hilda A. Pickett
- Telomere Length Regulation Unit, Children’s Medical Research Institute, University of Sydney, Westmead, NSW, Australia
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9
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Kalmykova A. Telomere Checkpoint in Development and Aging. Int J Mol Sci 2023; 24:15979. [PMID: 37958962 PMCID: PMC10647821 DOI: 10.3390/ijms242115979] [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: 09/01/2023] [Revised: 10/19/2023] [Accepted: 11/02/2023] [Indexed: 11/15/2023] Open
Abstract
The maintenance of genome integrity through generations is largely determined by the stability of telomeres. Increasing evidence suggests that telomere dysfunction may trigger changes in cell fate, independently of telomere length. Telomeric multiple tandem repeats are potentially highly recombinogenic. Heterochromatin formation, transcriptional repression, the suppression of homologous recombination and chromosome end protection are all required for telomere stability. Genetic and epigenetic defects affecting telomere homeostasis may cause length-independent internal telomeric DNA damage. Growing evidence, including that based on Drosophila research, points to a telomere checkpoint mechanism that coordinates cell fate with telomere state. According to this scenario, telomeres, irrespective of their length, serve as a primary sensor of genome instability that is capable of triggering cell death or developmental arrest. Telomeric factors released from shortened or dysfunctional telomeres are thought to mediate these processes. Here, we discuss a novel signaling role for telomeric RNAs in cell fate and early development. Telomere checkpoint ensures genome stability in multicellular organisms but aggravates the aging process, promoting the accumulation of damaged and senescent cells.
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Affiliation(s)
- Alla Kalmykova
- Koltzov Institute of Developmental Biology, Russian Academy of Sciences, 119334 Moscow, Russia
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10
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Tsai LK, Peng M, Chang CC, Wen L, Liu L, Liang X, Chen YE, Xu J, Sung LY. ZSCAN4 interacts with PARP1 to promote DNA repair in mouse embryonic stem cells. Cell Biosci 2023; 13:193. [PMID: 37875990 PMCID: PMC10594928 DOI: 10.1186/s13578-023-01140-1] [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] [Received: 03/31/2023] [Accepted: 10/05/2023] [Indexed: 10/26/2023] Open
Abstract
BACKGROUND In eukaryotic cells, DNA double strand breaks (DSB) are primarily repaired by canonical non-homologous end joining (c-NHEJ), homologous recombination (HR) and alternative NHEJ (alt-NHEJ). Zinc finger and SCAN domain containing 4 (ZSCAN4), sporadically expressed in 1-5% mouse embryonic stem cells (mESCs), is known to regulate genome stability by promoting HR. RESULTS Here we show that ZSCAN4 promotes DNA repair by acting with Poly (ADP-ribose) polymerase 1 (PARP1), which is a key member of the alt-NHEJ pathway. In the presence of PARP1, ZSCAN4-expressing mESCs are associated with lower extent of endogenous or chemical induced DSB comparing to ZSCAN4-negative ones. Reduced DSBs associated with ZSCAN4 are abolished by PARP1 inhibition, achieved either through small molecule inhibitor or gene knockout in mESCs. Furthermore, PARP1 binds directly to ZSCAN4, and the second ⍺-helix and the fourth zinc finger motif of ZSCAN4 are critical for this binding. CONCLUSIONS These data reveal that PARP1 and ZSCAN4 have a protein-protein interaction, and shed light on the molecular mechanisms by which ZSCAN4 reduces DSB in mESCs.
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Affiliation(s)
- Li-Kuang Tsai
- Institute of Biotechnology, National Taiwan University, Taipei, 106, Taiwan, ROC
| | - Min Peng
- Institute of Biotechnology, National Taiwan University, Taipei, 106, Taiwan, ROC
| | - Chia-Chun Chang
- Institute of Biotechnology, National Taiwan University, Taipei, 106, Taiwan, ROC
| | - Luan Wen
- Center for Advanced Models for Translational Sciences and Therapeutics, University of Michigan Medical School, Ann Arbor, MI, 48109, USA
| | - Lin Liu
- State Key Laboratory of Medicinal Chemical Biology, Department of Cell Biology and Genetics, College of Life Sciences, Nankai University, Tianjin, 300071, China
| | - Xiubin Liang
- Center for Advanced Models for Translational Sciences and Therapeutics, University of Michigan Medical School, Ann Arbor, MI, 48109, USA
| | - Y Eugene Chen
- Center for Advanced Models for Translational Sciences and Therapeutics, University of Michigan Medical School, Ann Arbor, MI, 48109, USA
| | - Jie Xu
- Center for Advanced Models for Translational Sciences and Therapeutics, University of Michigan Medical School, Ann Arbor, MI, 48109, USA.
| | - Li-Ying Sung
- Institute of Biotechnology, National Taiwan University, Taipei, 106, Taiwan, ROC.
- Center for Developmental Biology and Regenerative Medicine, Taipei, 106, Taiwan, ROC.
- Center for Biotechnology, National Taiwan University, Taipei, 106, Taiwan, ROC.
- Agricultural Biotechnology Research Center, Academia Sinica, Taipei, 115, Taiwan, ROC.
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11
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Myler LR, Toia B, Vaughan CK, Takai K, Matei AM, Wu P, Paull TT, de Lange T, Lottersberger F. DNA-PK and the TRF2 iDDR inhibit MRN-initiated resection at leading-end telomeres. Nat Struct Mol Biol 2023; 30:1346-1356. [PMID: 37653239 PMCID: PMC10497418 DOI: 10.1038/s41594-023-01072-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Accepted: 07/18/2023] [Indexed: 09/02/2023]
Abstract
Telomeres replicated by leading-strand synthesis lack the 3' overhang required for telomere protection. Surprisingly, resection of these blunt telomeres is initiated by the telomere-specific 5' exonuclease Apollo rather than the Mre11-Rad50-Nbs1 (MRN) complex, the nuclease that acts at DNA breaks. Without Apollo, leading-end telomeres undergo fusion, which, as demonstrated here, is mediated by alternative end joining. Here, we show that DNA-PK and TRF2 coordinate the repression of MRN at blunt mouse telomeres. DNA-PK represses an MRN-dependent long-range resection, while the endonuclease activity of MRN-CtIP, which could cleave DNA-PK off of blunt telomere ends, is inhibited in vitro and in vivo by the iDDR of TRF2. AlphaFold-Multimer predicts a conserved association of the iDDR with Rad50, potentially interfering with CtIP binding and MRN endonuclease activation. We propose that repression of MRN-mediated resection is a conserved aspect of telomere maintenance and represents an ancient feature of DNA-PK and the iDDR.
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Affiliation(s)
- Logan R Myler
- Laboratory for Cell Biology and Genetics, The Rockefeller University, New York, NY, USA
| | - Beatrice Toia
- Department of Biomedical and Clinical Sciences, Faculty of Medicine and Health Sciences, Linköping University, Linköping, Sweden
| | - Cara K Vaughan
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX, USA
| | - Kaori Takai
- Laboratory for Cell Biology and Genetics, The Rockefeller University, New York, NY, USA
| | - Andreea M Matei
- Department of Biomedical and Clinical Sciences, Faculty of Medicine and Health Sciences, Linköping University, Linköping, Sweden
| | - Peng Wu
- Laboratory for Cell Biology and Genetics, The Rockefeller University, New York, NY, USA
- Department of Pediatrics, Stanford University School of Medicine, Stanford, CA, USA
| | - Tanya T Paull
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX, USA
| | - Titia de Lange
- Laboratory for Cell Biology and Genetics, The Rockefeller University, New York, NY, USA.
| | - Francisca Lottersberger
- Department of Biomedical and Clinical Sciences, Faculty of Medicine and Health Sciences, Linköping University, Linköping, Sweden.
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12
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Zhang T, Rawal Y, Jiang H, Kwon Y, Sung P, Greenberg RA. Break-induced replication orchestrates resection-dependent template switching. Nature 2023; 619:201-208. [PMID: 37316655 PMCID: PMC10937050 DOI: 10.1038/s41586-023-06177-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2022] [Accepted: 05/05/2023] [Indexed: 06/16/2023]
Abstract
Break-induced telomere synthesis (BITS) is a RAD51-independent form of break-induced replication that contributes to alternative lengthening of telomeres1,2. This homology-directed repair mechanism utilizes a minimal replisome comprising proliferating cell nuclear antigen (PCNA) and DNA polymerase-δ to execute conservative DNA repair synthesis over many kilobases. How this long-tract homologous recombination repair synthesis responds to complex secondary DNA structures that elicit replication stress remains unclear3-5. Moreover, whether the break-induced replisome orchestrates additional DNA repair events to ensure processivity is also unclear. Here we combine synchronous double-strand break induction with proteomics of isolated chromatin segments (PICh) to capture the telomeric DNA damage response proteome during BITS1,6. This approach revealed a replication stress-dominated response, highlighted by repair synthesis-driven DNA damage tolerance signalling through RAD18-dependent PCNA ubiquitination. Furthermore, the SNM1A nuclease was identified as the major effector of ubiquitinated PCNA-dependent DNA damage tolerance. SNM1A recognizes the ubiquitin-modified break-induced replisome at damaged telomeres, and this directs its nuclease activity to promote resection. These findings show that break-induced replication orchestrates resection-dependent lesion bypass, with SNM1A nuclease activity serving as a critical effector of ubiquitinated PCNA-directed recombination in mammalian cells.
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Affiliation(s)
- Tianpeng Zhang
- Department of Cancer Biology, Penn Center for Genome Integrity, Basser Center for BRCA, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Yashpal Rawal
- Department of Biochemistry and Structural Biology and Greehey Children's Cancer Research Institute, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Haoyang Jiang
- Department of Cancer Biology, Penn Center for Genome Integrity, Basser Center for BRCA, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Youngho Kwon
- Department of Biochemistry and Structural Biology and Greehey Children's Cancer Research Institute, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Patrick Sung
- Department of Biochemistry and Structural Biology and Greehey Children's Cancer Research Institute, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA
| | - Roger A Greenberg
- Department of Cancer Biology, Penn Center for Genome Integrity, Basser Center for BRCA, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
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13
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Sun S, Ma W, Mao P. Analysis of MsTERT Gene Expression Profile in Alfalfa ( Medicago sativa) Indicates Their Response to Abiotic Stress and Seed Aging. PLANTS (BASEL, SWITZERLAND) 2023; 12:2036. [PMID: 37653953 PMCID: PMC10221914 DOI: 10.3390/plants12102036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2023] [Revised: 05/17/2023] [Accepted: 05/17/2023] [Indexed: 09/02/2023]
Abstract
Seed aging is always taken as a crucial factor for vigor loss due to delayed seed germination and seedling growth, which limits hay production. Many studies have found that telomeres are closely related to abiotic stress and seed vigor. However, the molecular mechanism of telomeres' response to abiotic stress, seed vigor, and the maintenance mechanism of plant telomere homeostasis still remain unclear. Alfalfa (Medicago sativa) enjoys the title of "King of Forage", and is an important protein forage for the dairy industry as planted in the world. This comprehensive investigation was performed to explore the molecular characterization, phylogenetic relationship, and gene expression analysis of MsTERT under abiotic stress and during seed aging in alfalfa. In this study, MsTERT was identified from the 'Zhongmu 1' alfalfa genome and encoded a coding sequence (CDS) of 3615 bp in length, consisting of telomerase- RNA-Binding Domain (RBD) and Reverse Transcriptase (RT) domains, 1024 amino acids, an isoelectric point of 9.58, and a relative molecular mass of 138.94 kD. Subcellular localization showed that MsTERT was mainly localized in the nucleus and mitochondria. The results of the expression profile showed that MsTERT was observed to respond to various stress conditions such as salt (100 mmol/L NaCl) and drought (20% PEG 6000). Furthermore, exogenous hormones IAA, ABA, and GA3 showed the potential to affect MsTERT expression. Additionally, MsTERT also responded to seed aging. Our results revealed a marginal but significant association between relative telomere length, MsTERT expression, and seed germination percentage, suggesting that the length of telomeres was shortened, and expression of MsTERT decreased with alfalfa seed aged. These results provide some evidence for the hypothesis of relative telomere length and/or TERT expression serving as biomarkers of seed aging. Although this finding is helpful to offer a new way to elucidate the molecular mechanism of vigor loss in alfalfa seed, further investigation is required to elucidate the molecular mechanism by which the MsTERT gene regulates seed vigor.
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Affiliation(s)
| | | | - Peisheng Mao
- Forage Seed Laboratory, College of Grassland Science and Technology, China Agricultural University, Beijing 100193, China; (S.S.); (W.M.)
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14
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Rai R, Biju K, Sun W, Sodeinde T, Al-Hiyasat A, Morgan J, Ye X, Li X, Chen Y, Chang S. Homology directed telomere clustering, ultrabright telomere formation and nuclear envelope rupture in cells lacking TRF2 B and RAP1. Nat Commun 2023; 14:2144. [PMID: 37059728 PMCID: PMC10104862 DOI: 10.1038/s41467-023-37761-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Accepted: 03/30/2023] [Indexed: 04/16/2023] Open
Abstract
Double-strand breaks (DSBs) due to genotoxic stress represent potential threats to genome stability. Dysfunctional telomeres are recognized as DSBs and are repaired by distinct DNA repair mechanisms. RAP1 and TRF2 are telomere binding proteins essential to protect telomeres from engaging in homology directed repair (HDR), but how this occurs remains unclear. In this study, we examined how the basic domain of TRF2 (TRF2B) and RAP1 cooperate to repress HDR at telomeres. Telomeres lacking TRF2B and RAP1 cluster into structures termed ultrabright telomeres (UTs). HDR factors localize to UTs, and UT formation is abolished by RNaseH1, DDX21 and ADAR1p110, suggesting that they contain DNA-RNA hybrids. Interaction between the BRCT domain of RAP1 and KU70/KU80 is also required to repress UT formation. Expressing TRF2∆B in Rap1-/- cells resulted in aberrant lamin A localization in the nuclear envelope and dramatically increased UT formation. Expressing lamin A phosphomimetic mutants induced nuclear envelope rupturing and aberrant HDR-mediated UT formation. Our results highlight the importance of shelterin and proteins in the nuclear envelope in repressing aberrant telomere-telomere recombination to maintain telomere homeostasis.
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Affiliation(s)
- Rekha Rai
- Department of Laboratory Medicine, Yale University School of Medicine, New Haven, 330 Cedar Street, CT, 06520, USA.
| | - Kevin Biju
- Department of Laboratory Medicine, Yale University School of Medicine, New Haven, 330 Cedar Street, CT, 06520, USA
- Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
| | - Wenqi Sun
- State Key Laboratory of Molecular Biology, National Center for Protein Science Shanghai, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, Shanghai, 200031, China
- University of Chinese Academy of Sciences, 100049, Beijing, China
| | - Tori Sodeinde
- Department of Laboratory Medicine, Yale University School of Medicine, New Haven, 330 Cedar Street, CT, 06520, USA
| | - Amer Al-Hiyasat
- Department of Laboratory Medicine, Yale University School of Medicine, New Haven, 330 Cedar Street, CT, 06520, USA
| | - Jaida Morgan
- Department of Laboratory Medicine, Yale University School of Medicine, New Haven, 330 Cedar Street, CT, 06520, USA
| | - Xianwen Ye
- University of Chinese Academy of Sciences, 100049, Beijing, China
- School of Life Science and Technology, ShanghaiTech University, 100 Haike Road, Shanghai, 201210, China
| | - Xueqing Li
- State Key Laboratory of Molecular Biology, National Center for Protein Science Shanghai, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, Shanghai, 200031, China
- University of Chinese Academy of Sciences, 100049, Beijing, China
| | - Yong Chen
- State Key Laboratory of Molecular Biology, National Center for Protein Science Shanghai, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, Shanghai, 200031, China
- University of Chinese Academy of Sciences, 100049, Beijing, China
- School of Life Science and Technology, ShanghaiTech University, 100 Haike Road, Shanghai, 201210, China
| | - Sandy Chang
- Department of Laboratory Medicine, Yale University School of Medicine, New Haven, 330 Cedar Street, CT, 06520, USA.
- Department of Pathology, Yale University School of Medicine, 330 Cedar Street, New Haven, CT, 06520, USA.
- Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, 330 Cedar Street, New Haven, CT, 06520, USA.
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15
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Maresca C, Dello Stritto A, D'Angelo C, Petti E, Rizzo A, Vertecchi E, Berardinelli F, Bonanni L, Sgura A, Antoccia A, Graziani G, Biroccio A, Salvati E. PARP1 allows proper telomere replication through TRF1 poly (ADP-ribosyl)ation and helicase recruitment. Commun Biol 2023; 6:234. [PMID: 36864251 PMCID: PMC9981704 DOI: 10.1038/s42003-023-04596-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2022] [Accepted: 02/15/2023] [Indexed: 03/04/2023] Open
Abstract
Telomeres are nucleoprotein structures at eukaryotic chromosome termini. Their stability is preserved by a six-protein complex named shelterin. Among these, TRF1 binds telomere duplex and assists DNA replication with mechanisms only partly clarified. Here we found that poly (ADP-ribose) polymerase 1 (PARP1) interacts and covalently PARylates TRF1 in S-phase modifying its DNA affinity. Therefore, genetic and pharmacological inhibition of PARP1 impairs the dynamic association of TRF1 and the bromodeoxyuridine incorporation at replicating telomeres. Inhibition of PARP1 also affects the recruitment of WRN and BLM helicases in TRF1 containing complexes during S-phase, triggering replication-dependent DNA-damage and telomere fragility. This work unveils an unprecedented role for PARP1 as a "surveillant" of telomere replication, which orchestrates protein dynamics at proceeding replication fork.
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Affiliation(s)
- C Maresca
- Translational Oncology Research Unit, IRCCS Regina Elena National Cancer Institute, Rome, Italy
| | - A Dello Stritto
- Department of Biology and Biotechnology "Charles Darwin", Sapienza University of Rome, Rome, Italy
- Institute of Molecular Genetics "Luigi Cavalli-Sforza", National Research Council, Via Abbiategrasso 207, Pavia, Italy
| | - C D'Angelo
- Translational Oncology Research Unit, IRCCS Regina Elena National Cancer Institute, Rome, Italy
| | - E Petti
- Translational Oncology Research Unit, IRCCS Regina Elena National Cancer Institute, Rome, Italy
| | - A Rizzo
- Translational Oncology Research Unit, IRCCS Regina Elena National Cancer Institute, Rome, Italy
| | - E Vertecchi
- Institute of Molecular Biology and Pathology, National Research Council, Rome, Italy
| | | | - L Bonanni
- Department of Biology, Roma Tre University, Rome, Italy
| | - A Sgura
- Department of Biology, Roma Tre University, Rome, Italy
| | - A Antoccia
- Department of Biology, Roma Tre University, Rome, Italy
| | - G Graziani
- Department of Systems Medicine, University of Rome Tor Vergata, Rome, Italy
| | - A Biroccio
- Translational Oncology Research Unit, IRCCS Regina Elena National Cancer Institute, Rome, Italy.
| | - E Salvati
- Institute of Molecular Biology and Pathology, National Research Council, Rome, Italy.
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16
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Storchova R, Palek M, Palkova N, Veverka P, Brom T, Hofr C, Macurek L. Phosphorylation of TRF2 promotes its interaction with TIN2 and regulates DNA damage response at telomeres. Nucleic Acids Res 2023; 51:1154-1172. [PMID: 36651296 PMCID: PMC9943673 DOI: 10.1093/nar/gkac1269] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Revised: 11/25/2022] [Accepted: 12/23/2022] [Indexed: 01/19/2023] Open
Abstract
Protein phosphatase magnesium-dependent 1 delta (PPM1D) terminates the cell cycle checkpoint by dephosphorylating the tumour suppressor protein p53. By targeting additional substrates at chromatin, PPM1D contributes to the control of DNA damage response and DNA repair. Using proximity biotinylation followed by proteomic analysis, we identified a novel interaction between PPM1D and the shelterin complex that protects telomeric DNA. In addition, confocal microscopy revealed that endogenous PPM1D localises at telomeres. Further, we found that ATR phosphorylated TRF2 at S410 after induction of DNA double strand breaks at telomeres and this modification increased after inhibition or loss of PPM1D. TRF2 phosphorylation stimulated its interaction with TIN2 both in vitro and at telomeres. Conversely, induced expression of PPM1D impaired localisation of TIN2 and TPP1 at telomeres. Finally, recruitment of the DNA repair factor 53BP1 to the telomeric breaks was strongly reduced after inhibition of PPM1D and was rescued by the expression of TRF2-S410A mutant. Our results suggest that TRF2 phosphorylation promotes the association of TIN2 within the shelterin complex and regulates DNA repair at telomeres.
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Affiliation(s)
- Radka Storchova
- Cancer Cell Biology, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague CZ-14220, Czech Republic
| | - Matous Palek
- Cancer Cell Biology, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague CZ-14220, Czech Republic
| | - Natalie Palkova
- Cancer Cell Biology, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague CZ-14220, Czech Republic
| | - Pavel Veverka
- LifeB, Functional Genomics and Proteomics, National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Brno CZ-62500, Czech Republic
| | - Tomas Brom
- LifeB, Functional Genomics and Proteomics, National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Brno CZ-62500, Czech Republic
| | - Ctirad Hofr
- LifeB, Functional Genomics and Proteomics, National Centre for Biomolecular Research, Faculty of Science, Masaryk University, Brno CZ-62500, Czech Republic
| | - Libor Macurek
- Cancer Cell Biology, Institute of Molecular Genetics of the Czech Academy of Sciences, Prague CZ-14220, Czech Republic
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17
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Ragupathi A, Singh M, Perez AM, Zhang D. Targeting the BRCA1/ 2 deficient cancer with PARP inhibitors: Clinical outcomes and mechanistic insights. Front Cell Dev Biol 2023; 11:1133472. [PMID: 37035242 PMCID: PMC10073599 DOI: 10.3389/fcell.2023.1133472] [Citation(s) in RCA: 16] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2022] [Accepted: 03/14/2023] [Indexed: 04/11/2023] Open
Abstract
BRCA1 and BRCA2 play a critical role in a variety of molecular processes related to DNA metabolism, including homologous recombination and mediating the replication stress response. Individuals with mutations in the BRCA1 and BRCA2 (BRCA1/2) genes have a significantly higher risk of developing various types of cancers, especially cancers of the breast, ovary, pancreas, and prostate. Currently, the Food and Drug Administration (FDA) has approved four PARP inhibitors (PARPi) to treat cancers with BRCA1/2 mutations. In this review, we will first summarize the clinical outcomes of the four FDA-approved PARPi in treating BRCA1/2 deficient cancers. We will then discuss evidence supporting the hypothesis that the cytotoxic effect of PARPi is likely due to inducing excessive replication stress at the difficult-to-replicate (DTR) genomic regions in BRCA1/2 mutated tumors. Finally, we will discuss the ongoing preclinical and clinical studies on how to combine the PARPi with immuno-oncology drugs to further improve clinical outcomes.
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18
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Wilson C, Murnane JP. High-throughput screen to identify compounds that prevent or target telomere loss in human cancer cells. NAR Cancer 2022; 4:zcac029. [PMID: 36196242 PMCID: PMC9527662 DOI: 10.1093/narcan/zcac029] [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: 06/27/2022] [Revised: 09/09/2022] [Accepted: 09/29/2022] [Indexed: 11/14/2022] Open
Abstract
Chromosome instability (CIN) is an early step in carcinogenesis that promotes tumor cell progression and resistance to therapy. Using plasmids integrated adjacent to telomeres, we have previously demonstrated that the sensitivity of subtelomeric regions to DNA double-strand breaks (DSBs) contributes to telomere loss and CIN in cancer. A high-throughput screen was created to identify compounds that affect telomere loss due to subtelomeric DSBs introduced by I-SceI endonuclease, as detected by cells expressing green fluorescent protein (GFP). A screen of a library of 1832 biologically-active compounds identified a variety of compounds that increase or decrease the number of GFP-positive cells following activation of I-SceI. A curated screen done in triplicate at various concentrations found that inhibition of classical nonhomologous end joining (C-NHEJ) increased DSB-induced telomere loss, demonstrating that C-NHEJ is functional in subtelomeric regions. Compounds that decreased DSB-induced telomere loss included inhibitors of mTOR, p38 and tankyrase, consistent with our earlier hypothesis that the sensitivity of subtelomeric regions to DSBs is a result of inappropriate resection during repair. Although this assay was also designed to identify compounds that selectively target cells experiencing telomere loss and/or chromosome instability, no compounds of this type were identified in the current screen.
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Affiliation(s)
- Chris Wilson
- Department of Pharmaceutical Chemistry, Small Molecule Discovery Center, University of California, San Francisco, CA 94143, USA
| | - John P Murnane
- To whom correspondence should be addressed. Tel: +1 415 680 4434;
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19
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Macha SJ, Koneru B, Burrow TA, Zhu C, Savitski D, Rahman RL, Ronaghan CA, Nance J, McCoy K, Eslinger C, Reynolds CP. Alternative Lengthening of Telomeres in Cancer Confers a Vulnerability to Reactivation of p53 Function. Cancer Res 2022; 82:3345-3358. [PMID: 35947641 PMCID: PMC9566554 DOI: 10.1158/0008-5472.can-22-0125] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Revised: 05/18/2022] [Accepted: 07/14/2022] [Indexed: 11/16/2022]
Abstract
A subset of cancers across multiple histologies with predominantly poor outcomes use the alternative lengthening of telomeres (ALT) mechanism to maintain telomere length, which can be identified with robust biomarkers. ALT has been reported to be prevalent in high-risk neuroblastoma and certain sarcomas, and ALT cancers are a major clinical challenge that lack targeted therapeutic approaches. Here, we found ALT in a variety of pediatric and adult cancer histologies, including carcinomas. Patient-derived ALT cancer cell lines from neuroblastomas, sarcomas, and carcinomas were hypersensitive to the p53 reactivator eprenetapopt (APR-246) relative to telomerase-positive (TA+) models. Constitutive telomere damage signaling in ALT cells activated ataxia-telangiectasia mutated (ATM) kinase to phosphorylate p53, which resulted in selective ALT sensitivity to APR-246. Treatment with APR-246 combined with irinotecan achieved complete responses in mice xenografted with ALT neuroblastoma, rhabdomyosarcoma, and breast cancer and delayed tumor growth in ALT colon cancer xenografts, while the combination had limited efficacy in TA+ tumor models. A large number of adult and pediatric cancers present with the ALT phenotype, which confers a uniquely high sensitivity to reactivation of p53. These data support clinical evaluation of a combinatorial approach using APR-246 and irinotecan in ALT patients with cancer. SIGNIFICANCE This work demonstrates that constitutive activation of ATM in chemotherapy-refractory ALT cancer cells renders them hypersensitive to reactivation of p53 function by APR-246, indicating a potential strategy to overcome therapeutic resistance.
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Affiliation(s)
- Shawn J. Macha
- Cancer Center, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, USA
- Department of Cell Biology & Biochemistry, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, USA
| | - Balakrishna Koneru
- Cancer Center, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, USA
- Department of Pediatrics, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, USA
| | - Trevor A. Burrow
- Cancer Center, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, USA
| | - Charles Zhu
- Cancer Center, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, USA
| | - Dzmitry Savitski
- Cancer Center, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, USA
| | - Rakhshanda L. Rahman
- Cancer Center, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, USA
- Department of Surgery, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, USA
| | - Catherine A. Ronaghan
- Cancer Center, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, USA
- Department of Surgery, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, USA
| | - Jonas Nance
- Cancer Center, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, USA
- Department of Pediatrics, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, USA
| | - Kristyn McCoy
- Cancer Center, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, USA
- Department of Pediatrics, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, USA
| | - Cody Eslinger
- Cancer Center, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, USA
| | - C. Patrick Reynolds
- Cancer Center, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, USA
- Department of Pediatrics, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, USA
- Department of Cell Biology & Biochemistry, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, USA
- Corresponding author. C. Patrick Reynolds, MD PhD, Cancer Center, School of Medicine, Texas Tech University Health Sciences Center; 3601 4th Street, Mail Stop 9445, Lubbock, Texas, USA. 79430-6450,
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20
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Liddiard K, Aston-Evans AN, Cleal K, Hendrickson E, Baird D. POLQ suppresses genome instability and alterations in DNA repeat tract lengths. NAR Cancer 2022; 4:zcac020. [PMID: 35774233 PMCID: PMC9241439 DOI: 10.1093/narcan/zcac020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Revised: 05/19/2022] [Accepted: 06/10/2022] [Indexed: 11/26/2022] Open
Abstract
DNA polymerase theta (POLQ) is a principal component of the alternative non-homologous end-joining (ANHEJ) DNA repair pathway that ligates DNA double-strand breaks. Utilizing independent models of POLQ insufficiency during telomere-driven crisis, we found that POLQ - /- cells are resistant to crisis-induced growth deceleration despite sustaining inter-chromosomal telomere fusion frequencies equivalent to wild-type (WT) cells. We recorded longer telomeres in POLQ - / - than WT cells pre- and post-crisis, notwithstanding elevated total telomere erosion and fusion rates. POLQ - /- cells emerging from crisis exhibited reduced incidence of clonal gross chromosomal abnormalities in accordance with increased genetic heterogeneity. High-throughput sequencing of telomere fusion amplicons from POLQ-deficient cells revealed significantly raised frequencies of inter-chromosomal fusions with correspondingly depreciated intra-chromosomal recombinations. Long-range interactions culminating in telomere fusions with centromere alpha-satellite repeats, as well as expansions in HSAT2 and HSAT3 satellite and contractions in ribosomal DNA repeats, were detected in POLQ - / - cells. In conjunction with the expanded telomere lengths of POLQ - /- cells, these results indicate a hitherto unrealized capacity of POLQ for regulation of repeat arrays within the genome. Our findings uncover novel considerations for the efficacy of POLQ inhibitors in clinical cancer interventions, where potential genome destabilizing consequences could drive clonal evolution and resistant disease.
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Affiliation(s)
- Kate Liddiard
- Division of Cancer and Genetics, School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4XN, UK
| | - Alys N Aston-Evans
- Dementia Research Institute, School of Medicine, Cardiff University, Hadyn Ellis Building, Maindy Road, Cardiff CF24 4HQ, UK
| | - Kez Cleal
- Division of Cancer and Genetics, School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4XN, UK
| | - Eric A Hendrickson
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota Medical School, Minneapolis, MN 55455, USA
| | - Duncan M Baird
- Division of Cancer and Genetics, School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4XN, UK
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21
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Yang Z, Sharma K, de Lange T. TRF1 uses a noncanonical function of TFIIH to promote telomere replication. Genes Dev 2022; 36:956-969. [PMID: 36229075 PMCID: PMC9732906 DOI: 10.1101/gad.349975.122] [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: 08/03/2022] [Accepted: 09/26/2022] [Indexed: 01/07/2023]
Abstract
Telomeric DNA challenges the replisome and requires TRF1 for efficient duplication. TRF1 recruits the BLM helicase, but BLM loss does not explain the extensive telomere fragility, ATR signaling, and sister telomere associations (STAs) induced by TRF1 deletion. Here, we document that Helix2 of the TRFH domain and Helix1 of the Myb domain of TRF1 are required for efficient telomere replication. Mutation of both helices generated a TRF1 separation-of-function mutant (TRF1-E83K/LW-TI) that induced severe telomere replication defects but no ATR signaling or STAs. We identified the transcription and nucleotide excision repair (NER) factor TFIIH as a critical effector of TRF1. Loss of TFIIH subunits, but no other NER factors, caused the same telomere replication phenotypes as the TRF1-E83K/LW-TI mutant independent of the effects on TRF1 expression. TFIIH subunits coimmunoprecipitated with wild-type TRF1 but not with TRF1-E83K/LW-TI. These results establish that the major mechanism by which TRF1 ensures telomere replication involves a noncanonical function of TFIIH.
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22
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Brenner KA, Nandakumar J. Consequences of telomere replication failure: the other end-replication problem. Trends Biochem Sci 2022; 47:506-517. [PMID: 35440402 PMCID: PMC9106919 DOI: 10.1016/j.tibs.2022.03.013] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Revised: 02/28/2022] [Accepted: 03/17/2022] [Indexed: 01/14/2023]
Abstract
Telomeres are chromosome-capping structures that protect ends of the linear genome from DNA damage sensors. However, these structures present obstacles during DNA replication. Incomplete telomere replication accelerates telomere shortening and limits replicative lifespan. Therefore, continued proliferation under conditions of replication stress requires a means of telomere repair, particularly in the absence of telomerase. It was recently revealed that replication stress triggers break-induced replication (BIR) and mitotic DNA synthesis (MiDAS) at mammalian telomeres; however, these mechanisms are error prone and primarily utilized in tumorigenic contexts. In this review article, we discuss the consequences of replication stress at telomeres and how use of available repair pathways contributes to genomic instability. Current research suggests that fragile telomeres are ultimately tumor-suppressive and thus may be better left unrepaired.
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Affiliation(s)
- Kirsten A Brenner
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA.
| | - Jayakrishnan Nandakumar
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA.
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23
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Muoio D, Laspata N, Fouquerel E. Functions of ADP-ribose transferases in the maintenance of telomere integrity. Cell Mol Life Sci 2022; 79:215. [PMID: 35348914 PMCID: PMC8964661 DOI: 10.1007/s00018-022-04235-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Revised: 03/03/2022] [Accepted: 03/07/2022] [Indexed: 12/21/2022]
Abstract
The ADP-ribose transferase (ART) family comprises 17 enzymes that catalyze mono- or poly-ADP-ribosylation, a post-translational modification of proteins. Present in all subcellular compartments, ARTs are implicated in a growing number of biological processes including DNA repair, replication, transcription regulation, intra- and extra-cellular signaling, viral infection and cell death. Five members of the family, PARP1, PARP2, PARP3, tankyrase 1 and tankyrase 2 are mainly described for their crucial functions in the maintenance of genome stability. It is well established that the most describedrole of PARP1, 2 and 3 is the repair of DNA lesions while tankyrases 1 and 2 are crucial for maintaining the integrity of telomeres. Telomeres, nucleoprotein complexes located at the ends of eukaryotic chromosomes, utilize their unique structure and associated set of proteins to orchestrate the mechanisms necessary for their own protection and replication. While the functions of tankyrases 1 and 2 at telomeres are well known, several studies have also brought PARP1, 2 and 3 to the forefront of telomere protection. The singular quality of the telomeric environment has highlighted protein interactions and molecular pathways distinct from those described throughout the genome. The aim of this review is to provide an overview of the current knowledge on the multiple roles of PARP1, PARP2, PARP3, tankyrase 1 and tankyrase 2 in the maintenance and preservation of telomere integrity.
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Affiliation(s)
- Daniela Muoio
- UPMC Cancer Institute and Department of Pharmacology and Chemical Biology at the University of Pittsburgh, Hillman Cancer Center, 5115 Centre Avenue, Pittsburgh, PA, 15213, USA
| | - Natalie Laspata
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, 233 S. 10th street, Philadelphia, PA, 19107, USA
| | - Elise Fouquerel
- UPMC Cancer Institute and Department of Pharmacology and Chemical Biology at the University of Pittsburgh, Hillman Cancer Center, 5115 Centre Avenue, Pittsburgh, PA, 15213, USA.
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24
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Zhou Z, Li Y, Xu H, Xie X, He Z, Lin S, Li R, Jin S, Cui J, Hu H, Liu F, Wu S, Ma W, Songyang Z. An inducible CRISPR/Cas9 screen identifies DTX2 as a transcriptional regulator of human telomerase. iScience 2022; 25:103813. [PMID: 35198878 PMCID: PMC8844827 DOI: 10.1016/j.isci.2022.103813] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 12/07/2021] [Accepted: 01/20/2022] [Indexed: 01/12/2023] Open
Abstract
Most tumor cells reactivate telomerase to ensure unlimited proliferation, whereas the expression of human telomerase reverse transcriptase (hTERT) is tightly regulated and rate-limiting for telomerase activity maintenance. Several general transcription factors (TFs) have been found in regulating hTERT transcription; however, a systematic study is lacking. Here we performed an inducible CRISPR/Cas9 KO screen using an hTERT core promoter-driven reporter. We identified numerous positive regulators including an E3 ligase DTX2. In telomerase-positive cancer cells, DTX2 depletion downregulated hTERT transcription and telomerase activity, contributing to progressive telomere shortening, growth arrest, and increased apoptosis. Utilizing BioID, we characterized multiple TFs as DTX2 proximal proteins, among which NFIC functioned corporately with DTX2 in promoting hTERT transcription. Further analysis demonstrated that DTX2 mediated K63-linked ubiquitination of NFIC, which facilitated NFIC binding to the hTERT promoter and enhanced hTERT expression. These findings highlight a new hTERT regulatory pathway that may be exploited for potential cancer therapeutics. An inducible CRISPR/Cas9 screen identifies regulators for hTERT transcription DTX2 deficiency leads to telomere shortening and cell growth arrest DTX2 mediates ubiquitination on NFIC, stabilizing NFIC binding on hTERT promoter DTX2-NFIC functions corporately to promote hTERT transcription and tumorigenesis
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Affiliation(s)
- Zhifen Zhou
- Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou 510120, China
- MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, Guangzhou Key Laboratory of Healthy Aging Research, Institute of Healthy Aging Research, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
| | - Yujing Li
- MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, Guangzhou Key Laboratory of Healthy Aging Research, Institute of Healthy Aging Research, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
| | - Huimin Xu
- MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, Guangzhou Key Laboratory of Healthy Aging Research, Institute of Healthy Aging Research, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
| | - Xiaowei Xie
- MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, Guangzhou Key Laboratory of Healthy Aging Research, Institute of Healthy Aging Research, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
| | - Zibin He
- MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, Guangzhou Key Laboratory of Healthy Aging Research, Institute of Healthy Aging Research, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
| | - Song Lin
- MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, Guangzhou Key Laboratory of Healthy Aging Research, Institute of Healthy Aging Research, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
| | - Ruofei Li
- MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, Guangzhou Key Laboratory of Healthy Aging Research, Institute of Healthy Aging Research, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
| | - Shouheng Jin
- MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, Guangzhou Key Laboratory of Healthy Aging Research, Institute of Healthy Aging Research, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
| | - Jun Cui
- MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, Guangzhou Key Laboratory of Healthy Aging Research, Institute of Healthy Aging Research, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
| | - Hai Hu
- Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou 510120, China
| | - Feng Liu
- MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, Guangzhou Key Laboratory of Healthy Aging Research, Institute of Healthy Aging Research, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
| | - Su Wu
- Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou 510120, China
- MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, Guangzhou Key Laboratory of Healthy Aging Research, Institute of Healthy Aging Research, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
- Corresponding author
| | - Wenbin Ma
- MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, Guangzhou Key Laboratory of Healthy Aging Research, Institute of Healthy Aging Research, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
- Corresponding author
| | - Zhou Songyang
- Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou 510120, China
- MOE Key Laboratory of Gene Function and Regulation, State Key Laboratory of Biocontrol, Guangzhou Key Laboratory of Healthy Aging Research, Institute of Healthy Aging Research, School of Life Sciences, Sun Yat-sen University, Guangzhou 510275, China
- Bioland Laboratory (Guangzhou Regenerative Medicine and Health Guangdong Laboratory), Guangzhou 510005, China
- Corresponding author
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25
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Kent T, Clynes D. Alternative Lengthening of Telomeres: Lessons to Be Learned from Telomeric DNA Double-Strand Break Repair. Genes (Basel) 2021; 12:1734. [PMID: 34828344 PMCID: PMC8619803 DOI: 10.3390/genes12111734] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Revised: 10/22/2021] [Accepted: 10/28/2021] [Indexed: 12/25/2022] Open
Abstract
The study of the molecular pathways underlying cancer has given us important insights into how breaks in our DNA are repaired and the dire consequences that can occur when these processes are perturbed. Extensive research over the past 20 years has shown that the key molecular event underpinning a subset of cancers involves the deregulated repair of DNA double-strand breaks (DSBs) at telomeres, which in turn leads to telomere lengthening and the potential for replicative immortality. Here we discuss, in-depth, recent major breakthroughs in our understanding of the mechanisms underpinning this pathway known as the alternative lengthening of telomeres (ALT). We explore how this gives us important insights into how DSB repair at telomeres is regulated, with relevance to the cell-cycle-dependent regulation of repair, repair of stalled replication forks and the spatial regulation of DSB repair.
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Affiliation(s)
- Thomas Kent
- Molecular Haematology Unit, Radcliffe Department of Medicine, The MRC Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford OX3 9DS, UK;
| | - David Clynes
- Department of Oncology, The MRC Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Oxford OX3 9DS, UK
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26
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Abstract
Telomeres protect chromosome ends from nucleolytic degradation, uncontrolled recombination by DNA repair enzymes and checkpoint signaling, and they provide mechanisms for their maintenance by semiconservative DNA replication, telomerase and homologous recombination. The telomeric long noncoding RNA TERRA is transcribed from a large number of chromosome ends. TERRA has been implicated in modulating telomeric chromatin structure and checkpoint signaling, and in telomere maintenance by homology directed repair, and telomerase – when telomeres are damaged or very short. Recent work indicates that TERRA association with telomeres involves the formation of DNA:RNA hybrid structures that can be formed post transcription by the RAD51 DNA recombinase, which in turn may trigger homologous recombination between telomeric repeats and telomere elongation. In this review, we describe the mechanisms of TERRA recruitment to telomeres, R-loop formation and its regulation by shelterin proteins. We discuss the consequences of R-loop formation, with regard to telomere maintenance by DNA recombination and how this may impinge on telomere replication while counteracting telomere shortening in normal cells and in ALT cancer cells, which maintain telomeres in the absence of telomerase.
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Affiliation(s)
- Rita Valador Fernandes
- School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), Swiss Institute for Experimental Cancer Research (ISREC), Lausanne, Switzerland
| | - Marianna Feretzaki
- School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), Swiss Institute for Experimental Cancer Research (ISREC), Lausanne, Switzerland
| | - Joachim Lingner
- School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), Swiss Institute for Experimental Cancer Research (ISREC), Lausanne, Switzerland
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27
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Koneru B, Farooqi A, Nguyen TH, Chen WH, Hindle A, Eslinger C, Makena MR, Burrow TA, Wilson J, Smith A, Pilla Reddy V, Cadogan E, Durant ST, Reynolds CP. ALT neuroblastoma chemoresistance due to telomere dysfunction-induced ATM activation is reversible with ATM inhibitor AZD0156. Sci Transl Med 2021; 13:13/607/eabd5750. [PMID: 34408079 DOI: 10.1126/scitranslmed.abd5750] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 03/10/2021] [Accepted: 05/14/2021] [Indexed: 12/26/2022]
Abstract
Cancers overcome replicative immortality by activating either telomerase or an alternative lengthening of telomeres (ALT) mechanism. ALT occurs in ~25% of high-risk neuroblastomas, and progression in patients with ALT neuroblastoma during or after front-line therapy is frequent and often fatal. Temozolomide + irinotecan is commonly used as salvage therapy for neuroblastoma. Patient-derived cell lines and xenografts established from patients with relapsed ALT neuroblastoma demonstrated de novo resistance to temozolomide + irinotecan [SN-38 in vitro, P < 0.05; in vivo mouse event-free survival (EFS), P < 0.0001] vs. telomerase-positive neuroblastomas. We observed that ALT neuroblastoma cells manifested constitutive ataxia-telangiectasia mutated (ATM) activation due to spontaneous telomere dysfunction which was not observed in telomerase-positive neuroblastoma cells. We demonstrated that induction of telomere dysfunction resulted in ATM activation that, in turn, conferred resistance to temozolomide + SN-38 (4.2-fold change in IC50, P < 0.001). ATM knockdown (shRNA) or inhibition using a clinical-stage small-molecule inhibitor (AZD0156) reversed resistance to temozolomide + irinotecan in ALT neuroblastoma cell lines in vitro (P < 0.001) and in four ALT xenografts in vivo (EFS, P < 0.0001). AZD0156 showed modest to no enhancement of temozolomide + irinotecan activity in telomerase-positive neuroblastoma cell lines and xenografts. Ataxia telangiectasia and Rad3 related (ATR) inhibition using AZD6738 did not enhance temozolomide + SN-38 activity in ALT neuroblastoma cells. Thus, ALT neuroblastoma chemotherapy resistance occurs via ATM activation and is reversible with ATM inhibitor AZD0156. Combining AZD0156 with temozolomide + irinotecan warrants clinical testing for neuroblastoma.
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Affiliation(s)
- Balakrishna Koneru
- Cancer Center, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA.,Department of Pediatrics, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA.,Department of Cell Biology and Biochemistry, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
| | - Ahsan Farooqi
- Cancer Center, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
| | - Thinh H Nguyen
- Cancer Center, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
| | - Wan Hsi Chen
- Cancer Center, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
| | - Ashly Hindle
- Cancer Center, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA.,Department of Cell Biology and Biochemistry, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
| | - Cody Eslinger
- Cancer Center, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
| | - Monish Ram Makena
- Cancer Center, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
| | - Trevor A Burrow
- Cancer Center, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
| | - Joanne Wilson
- Early Oncology, R&D AstraZeneca, Cambridge CB10 1XL, UK
| | - Aaron Smith
- Early Oncology, R&D AstraZeneca, Cambridge CB10 1XL, UK
| | - Venkatesh Pilla Reddy
- Clinical Pharmacology and Quantitative Pharmacology, Biopharmaceuticals R&D, AstraZeneca, Cambridge SG8 6EE, UK
| | | | | | - C Patrick Reynolds
- Cancer Center, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA. .,Department of Pediatrics, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA.,Department of Cell Biology and Biochemistry, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA.,Department of Internal Medicine, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
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28
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Lee JH, Hong J, Zhang Z, de la Peña Avalos B, Proietti CJ, Deamicis AR, Guzmán G P, Lam HM, Garcia J, Roudier MP, Sisk AE, De La Rosa R, Vu K, Yang M, Liao Y, Scheirer J, Pechacek D, Yadav P, Rao MK, Zheng S, Johnson-Pais TL, Leach RJ, Elizalde PV, Dray E, Xu K. Regulation of telomere homeostasis and genomic stability in cancer by N 6-adenosine methylation (m 6A). SCIENCE ADVANCES 2021; 7:7/31/eabg7073. [PMID: 34321211 PMCID: PMC8318370 DOI: 10.1126/sciadv.abg7073] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2021] [Accepted: 06/11/2021] [Indexed: 05/04/2023]
Abstract
The role of RNA methylation on N 6-adenosine (m6A) in cancer has been acknowledged, but the underlying mechanisms remain obscure. Here, we identified homeobox containing 1 (HMBOX1) as an authentic target mRNA of m6A machinery, which is highly methylated in malignant cells compared to the normal counterparts and subject to expedited degradation upon the modification. m6A-mediated down-regulation of HMBOX1 causes telomere dysfunction and inactivation of p53 signaling, which leads to chromosome abnormalities and aggressive phenotypes. CRISPR-based, m6A-editing tools further prove that the methyl groups on HMBOX1 per se contribute to the generation of altered cancer genome. In multiple types of human cancers, expression of the RNA methyltransferase METTL3 is negatively correlated with the telomere length but favorably with fractions of altered cancer genome, whereas HMBOX1 mRNA levels show the opposite patterns. Our work suggests that the cancer-driving genomic alterations may potentially be fixed by rectifying particular epitranscriptomic program.
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Affiliation(s)
- Ji Hoon Lee
- Department of Molecular Medicine, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
| | - Juyeong Hong
- Department of Molecular Medicine, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
| | - Zhao Zhang
- Department of Molecular Medicine, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
| | - Bárbara de la Peña Avalos
- Department of Biochemistry and Structural Biology, University of Texas Health San Antonio, San Antonio, TX 78229, USA
- Mays Cancer Center, UT Health San Antonio MD Anderson, San Antonio, TX 78229, USA
| | - Cecilia J Proietti
- Laboratory of Molecular Mechanisms of Carcinogenesis and Molecular Endocrinology, Instituto de Biología y Medicina Experimental (IBYME), CONICET, Buenos Aires C1428ADN, Argentina
| | - Agustina Roldán Deamicis
- Laboratory of Molecular Mechanisms of Carcinogenesis and Molecular Endocrinology, Instituto de Biología y Medicina Experimental (IBYME), CONICET, Buenos Aires C1428ADN, Argentina
| | - Pablo Guzmán G
- Departamento de Anatomía Patológica (BIOREN), Universidad de La Frontera, Temuco Casilla 54-D, Chile
| | - Hung-Ming Lam
- Department of Urology, University of Washington, Seattle, WA 98195, USA
| | - Jose Garcia
- Department of Urology, University of Washington, Seattle, WA 98195, USA
| | - Martine P Roudier
- Department of Urology, University of Washington, Seattle, WA 98195, USA
| | - Anthony E Sisk
- Department of Pathology, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, CA 90095, USA
| | - Richard De La Rosa
- Department of Molecular Medicine, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
| | - Kevin Vu
- Department of Medical Education, Joe R. and Teresa Lozano Long School of Medicine, San Antonio, TX 78229, USA
| | - Mei Yang
- Department of Molecular Medicine, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
| | - Yiji Liao
- Department of Molecular Medicine, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
| | - Jessica Scheirer
- Department of Molecular Medicine, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
| | - Douglas Pechacek
- Department of Molecular Medicine, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
| | - Pooja Yadav
- Department of Cell Systems and Anatomy, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
- Greehey Children's Cancer Research Institute, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
| | - Manjeet K Rao
- Department of Cell Systems and Anatomy, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
- Greehey Children's Cancer Research Institute, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
| | - Siyuan Zheng
- Greehey Children's Cancer Research Institute, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
- Department of Population Health Sciences, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
| | - Teresa L Johnson-Pais
- Department of Urology, University of Texas Health Sciences Center at San Antonio, San Antonio, TX 78229, USA
| | - Robin J Leach
- Mays Cancer Center, UT Health San Antonio MD Anderson, San Antonio, TX 78229, USA
- Department of Cell Systems and Anatomy, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA
| | - Patricia V Elizalde
- Laboratory of Molecular Mechanisms of Carcinogenesis and Molecular Endocrinology, Instituto de Biología y Medicina Experimental (IBYME), CONICET, Buenos Aires C1428ADN, Argentina
| | - Eloïse Dray
- Department of Biochemistry and Structural Biology, University of Texas Health San Antonio, San Antonio, TX 78229, USA
- Mays Cancer Center, UT Health San Antonio MD Anderson, San Antonio, TX 78229, USA
| | - Kexin Xu
- Department of Molecular Medicine, University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA.
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29
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Dewhurst SM, Yao X, Rosiene J, Tian H, Behr J, Bosco N, Takai KK, de Lange T, Imieliński M. Structural variant evolution after telomere crisis. Nat Commun 2021; 12:2093. [PMID: 33828097 PMCID: PMC8027843 DOI: 10.1038/s41467-021-21933-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Accepted: 02/17/2021] [Indexed: 01/14/2023] Open
Abstract
Telomere crisis contributes to cancer genome evolution, yet only a subset of cancers display breakage-fusion-bridge (BFB) cycles and chromothripsis, hallmarks of experimental telomere crisis identified in previous studies. We examine the spectrum of structural variants (SVs) instigated by natural telomere crisis. Eight spontaneous post-crisis clones did not show prominent patterns of BFB cycles or chromothripsis. Their crisis-induced genome rearrangements varied from infrequent simple SVs to more frequent and complex SVs. In contrast, BFB cycles and chromothripsis occurred in MRC5 fibroblast clones that escaped telomere crisis after CRISPR-controlled telomerase activation. This system revealed convergent evolutionary lineages altering one allele of chromosome 12p, where a short telomere likely predisposed to fusion. Remarkably, the 12p chromothripsis and BFB events were stabilized by independent fusions to chromosome 21. The data establish that telomere crisis can generate a wide spectrum of SVs implying that a lack of BFB patterns and chromothripsis in cancer genomes does not indicate absence of past telomere crisis. Telomere crisis has been shown to induce chromothripsis and breakage fusion bridge (BFB) cycles in vitro. Here, the authors show that telomere crisis generates a much broader spectrum of structural variations, implying that cancers without chromothripsis and BFB cycles could have emerged from telomere crisis.
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Affiliation(s)
- Sally M Dewhurst
- Laboratory of Cell Biology and Genetics, Rockefeller University, New York, NY, USA
| | - Xiaotong Yao
- Tri-Institutional Ph.D. Program in Computational Biology and Medicine, Weill Cornell Medicine, New York, NY, USA.,Department of Pathology and Laboratory Medicine, Englander Institute for Precision Medicine, Institute for Computational Biomedicine, and Meyer Cancer Center, Weill Cornell Medicine, New York, NY, USA.,New York Genome Center, New York, NY, USA
| | - Joel Rosiene
- Department of Pathology and Laboratory Medicine, Englander Institute for Precision Medicine, Institute for Computational Biomedicine, and Meyer Cancer Center, Weill Cornell Medicine, New York, NY, USA.,New York Genome Center, New York, NY, USA
| | - Huasong Tian
- Department of Pathology and Laboratory Medicine, Englander Institute for Precision Medicine, Institute for Computational Biomedicine, and Meyer Cancer Center, Weill Cornell Medicine, New York, NY, USA.,New York Genome Center, New York, NY, USA
| | - Julie Behr
- Tri-Institutional Ph.D. Program in Computational Biology and Medicine, Weill Cornell Medicine, New York, NY, USA.,Department of Pathology and Laboratory Medicine, Englander Institute for Precision Medicine, Institute for Computational Biomedicine, and Meyer Cancer Center, Weill Cornell Medicine, New York, NY, USA.,New York Genome Center, New York, NY, USA
| | - Nazario Bosco
- Laboratory of Cell Biology and Genetics, Rockefeller University, New York, NY, USA.,Department of Biochemistry and Molecular Pharmacology, Institute for Systems Genetics, NYU Langone Health, New York, NY, USA
| | - Kaori K Takai
- Laboratory of Cell Biology and Genetics, Rockefeller University, New York, NY, USA
| | - Titia de Lange
- Laboratory of Cell Biology and Genetics, Rockefeller University, New York, NY, USA.
| | - Marcin Imieliński
- Department of Pathology and Laboratory Medicine, Englander Institute for Precision Medicine, Institute for Computational Biomedicine, and Meyer Cancer Center, Weill Cornell Medicine, New York, NY, USA. .,New York Genome Center, New York, NY, USA.
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30
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Ogrodnik M. Cellular aging beyond cellular senescence: Markers of senescence prior to cell cycle arrest in vitro and in vivo. Aging Cell 2021; 20:e13338. [PMID: 33711211 PMCID: PMC8045927 DOI: 10.1111/acel.13338] [Citation(s) in RCA: 111] [Impact Index Per Article: 37.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Revised: 02/09/2021] [Accepted: 02/19/2021] [Indexed: 12/14/2022] Open
Abstract
The field of research on cellular senescence experienced a rapid expansion from being primarily focused on in vitro aspects of aging to the vast territories of animal and clinical research. Cellular senescence is defined by a set of markers, many of which are present and accumulate in a gradual manner prior to senescence induction or are found outside of the context of cellular senescence. These markers are now used to measure the impact of cellular senescence on aging and disease as well as outcomes of anti-senescence interventions, many of which are at the stage of clinical trials. It is thus of primary importance to discuss their specificity as well as their role in the establishment of senescence. Here, the presence and role of senescence markers are described in cells prior to cell cycle arrest, especially in the context of replicative aging and in vivo conditions. Specifically, this review article seeks to describe the process of "cellular aging": the progression of internal changes occurring in primary cells leading to the induction of cellular senescence and culminating in cell death. Phenotypic changes associated with aging prior to senescence induction will be characterized, as well as their effect on the induction of cell senescence and the final fate of cells reviewed. Using published datasets on assessments of senescence markers in vivo, it will be described how disparities between quantifications can be explained by the concept of cellular aging. Finally, throughout the article the applicational value of broadening cellular senescence paradigm will be discussed.
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Affiliation(s)
- Mikolaj Ogrodnik
- Ludwig Boltzmann Research Group Senescence and Healing of Wounds Vienna Austria
- Ludwig Boltzmann Institute for Experimental and Clinical Traumatology in AUVA Research Center Vienna Austria
- Austrian Cluster for Tissue Regeneration Vienna Austria
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31
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Nelson CB, Alturki TM, Luxton JJ, Taylor LE, Maranon DG, Muraki K, Murnane JP, Bailey SM. Telomeric Double Strand Breaks in G1 Human Cells Facilitate Formation of 5' C-Rich Overhangs and Recruitment of TERRA. Front Genet 2021; 12:644803. [PMID: 33841503 PMCID: PMC8027502 DOI: 10.3389/fgene.2021.644803] [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: 12/21/2020] [Accepted: 02/08/2021] [Indexed: 12/12/2022] Open
Abstract
Telomeres, repetitive nucleoprotein complexes that protect chromosomal termini and prevent them from activating inappropriate DNA damage responses (DDRs), shorten with cell division and thus with aging. Here, we characterized the human cellular response to targeted telomeric double-strand breaks (DSBs) in telomerase-positive and telomerase-independent alternative lengthening of telomere (ALT) cells, specifically in G1 phase. Telomeric DSBs in human G1 cells elicited early signatures of a DDR; however, localization of 53BP1, an important regulator of resection at broken ends, was not observed at telomeric break sites. Consistent with this finding and previously reported repression of classical non-homologous end-joining (c-NHEJ) at telomeres, evidence for c-NHEJ was also lacking. Likewise, no evidence of homologous recombination (HR)-dependent repair of telomeric DSBs in G1 was observed. Rather, and supportive of rapid truncation events, telomeric DSBs in G1 human cells facilitated formation of extensive tracks of resected 5′ C-rich telomeric single-stranded (ss)DNA, a previously proposed marker of the recombination-dependent ALT pathway. Indeed, induction of telomeric DSBs in human ALT cells resulted in significant increases in 5′ C-rich (ss)telomeric DNA in G1, which rather than RPA, was bound by the complementary telomeric RNA, TERRA, presumably to protect these exposed ends so that they persist into S/G2 for telomerase-mediated or HR-dependent elongation, while also circumventing conventional repair pathways. Results demonstrate the remarkable adaptability of telomeres, and thus they have important implications for persistent telomeric DNA damage in normal human G1/G0 cells (e.g., lymphocytes), as well as for therapeutically relevant targets to improve treatment of ALT-positive tumors.
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Affiliation(s)
- Christopher B Nelson
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, CO, United States.,Cell and Molecular Biology Program, Colorado State University, Fort Collins, CO, United States
| | - Taghreed M Alturki
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, CO, United States.,Cell and Molecular Biology Program, Colorado State University, Fort Collins, CO, United States
| | - Jared J Luxton
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, CO, United States.,Cell and Molecular Biology Program, Colorado State University, Fort Collins, CO, United States
| | - Lynn E Taylor
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, CO, United States
| | - David G Maranon
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, CO, United States
| | - Keiko Muraki
- Department of Radiation Oncology, University of California, San Francisco, San Francisco, CA, United States
| | - John P Murnane
- Department of Radiation Oncology, University of California, San Francisco, San Francisco, CA, United States
| | - Susan M Bailey
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, CO, United States.,Cell and Molecular Biology Program, Colorado State University, Fort Collins, CO, United States
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Baxley RM, Leung W, Schmit MM, Matson JP, Yin L, Oram MK, Wang L, Taylor J, Hedberg J, Rogers CB, Harvey AJ, Basu D, Taylor JC, Pagnamenta AT, Dreau H, Craft J, Ormondroyd E, Watkins H, Hendrickson EA, Mace EM, Orange JS, Aihara H, Stewart GS, Blair E, Cook JG, Bielinsky AK. Bi-allelic MCM10 variants associated with immune dysfunction and cardiomyopathy cause telomere shortening. Nat Commun 2021; 12:1626. [PMID: 33712616 PMCID: PMC7955084 DOI: 10.1038/s41467-021-21878-x] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Accepted: 02/11/2021] [Indexed: 12/22/2022] Open
Abstract
Minichromosome maintenance protein 10 (MCM10) is essential for eukaryotic DNA replication. Here, we describe compound heterozygous MCM10 variants in patients with distinctive, but overlapping, clinical phenotypes: natural killer (NK) cell deficiency (NKD) and restrictive cardiomyopathy (RCM) with hypoplasia of the spleen and thymus. To understand the mechanism of MCM10-associated disease, we modeled these variants in human cell lines. MCM10 deficiency causes chronic replication stress that reduces cell viability due to increased genomic instability and telomere erosion. Our data suggest that loss of MCM10 function constrains telomerase activity by accumulating abnormal replication fork structures enriched with single-stranded DNA. Terminally-arrested replication forks in MCM10-deficient cells require endonucleolytic processing by MUS81, as MCM10:MUS81 double mutants display decreased viability and accelerated telomere shortening. We propose that these bi-allelic variants in MCM10 predispose specific cardiac and immune cell lineages to prematurely arrest during differentiation, causing the clinical phenotypes observed in both NKD and RCM patients.
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Affiliation(s)
- Ryan M Baxley
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Wendy Leung
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Megan M Schmit
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Jacob Peter Matson
- Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC, 27599, USA
| | - Lulu Yin
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Marissa K Oram
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Liangjun Wang
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN, 55455, USA
| | - John Taylor
- Oxford Medical Genetics Laboratories, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Jack Hedberg
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Colette B Rogers
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Adam J Harvey
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Debashree Basu
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Jenny C Taylor
- Wellcome Centre Human Genetics, University of Oxford, Oxford, OX3 7BN, UK
- Oxford NIHR Biomedical Research Centre, Oxford, OX3 7BN, UK
| | - Alistair T Pagnamenta
- Wellcome Centre Human Genetics, University of Oxford, Oxford, OX3 7BN, UK
- Oxford NIHR Biomedical Research Centre, Oxford, OX3 7BN, UK
| | - Helene Dreau
- Department of Haematology, University of Oxford, Oxford, OX3 7BN, UK
| | - Jude Craft
- Oxford Centre for Genomic Medicine, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Elizabeth Ormondroyd
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - Hugh Watkins
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, UK
| | - Eric A Hendrickson
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Emily M Mace
- Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, 10032, USA
| | - Jordan S Orange
- Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, 10032, USA
| | - Hideki Aihara
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Grant S Stewart
- Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham, B15 2TT, UK
| | - Edward Blair
- Oxford Centre for Genomic Medicine, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
| | - Jeanette Gowen Cook
- Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC, 27599, USA
| | - Anja-Katrin Bielinsky
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN, 55455, USA.
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Mentegari E, Bertoletti F, Kissova M, Zucca E, Galli S, Tagliavini G, Garbelli A, Maffia A, Bione S, Ferrari E, d’Adda di Fagagna F, Francia S, Sabbioneda S, Chen LY, Lingner J, Bergoglio V, Hoffmann JS, Hübscher U, Crespan E, Maga G. A Role for Human DNA Polymerase λ in Alternative Lengthening of Telomeres. Int J Mol Sci 2021; 22:ijms22052365. [PMID: 33673424 PMCID: PMC7956399 DOI: 10.3390/ijms22052365] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Revised: 02/13/2021] [Accepted: 02/23/2021] [Indexed: 12/15/2022] Open
Abstract
Telomerase negative cancer cell types use the Alternative Lengthening of Telomeres (ALT) pathway to elongate telomeres ends. Here, we show that silencing human DNA polymerase (Pol λ) in ALT cells represses ALT activity and induces telomeric stress. In addition, replication stress in the absence of Pol λ, strongly affects the survival of ALT cells. In vitro, Pol λ can promote annealing of even a single G-rich telomeric repeat to its complementary strand and use it to prime DNA synthesis. The noncoding telomeric repeat containing RNA TERRA and replication protein A negatively regulate this activity, while the Protection of Telomeres protein 1 (POT1)/TPP1 heterodimer stimulates Pol λ. Pol λ associates with telomeres and colocalizes with TPP1 in cells. In summary, our data suggest a role of Pol λ in the maintenance of telomeres by the ALT mechanism.
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Affiliation(s)
- Elisa Mentegari
- Institute of Molecular Genetics IGM-CNR “Luigi Luca Cavalli-Sforza”, via Abbiategrasso 207, 27100 Pavia, Italy; (E.M.); (F.B.); (M.K.); (E.Z.); (S.G.); (G.T.); (A.G.); (A.M.); (S.B.); (F.d.d.F.); (S.F.); (S.S.)
| | - Federica Bertoletti
- Institute of Molecular Genetics IGM-CNR “Luigi Luca Cavalli-Sforza”, via Abbiategrasso 207, 27100 Pavia, Italy; (E.M.); (F.B.); (M.K.); (E.Z.); (S.G.); (G.T.); (A.G.); (A.M.); (S.B.); (F.d.d.F.); (S.F.); (S.S.)
| | - Miroslava Kissova
- Institute of Molecular Genetics IGM-CNR “Luigi Luca Cavalli-Sforza”, via Abbiategrasso 207, 27100 Pavia, Italy; (E.M.); (F.B.); (M.K.); (E.Z.); (S.G.); (G.T.); (A.G.); (A.M.); (S.B.); (F.d.d.F.); (S.F.); (S.S.)
| | - Elisa Zucca
- Institute of Molecular Genetics IGM-CNR “Luigi Luca Cavalli-Sforza”, via Abbiategrasso 207, 27100 Pavia, Italy; (E.M.); (F.B.); (M.K.); (E.Z.); (S.G.); (G.T.); (A.G.); (A.M.); (S.B.); (F.d.d.F.); (S.F.); (S.S.)
| | - Silvia Galli
- Institute of Molecular Genetics IGM-CNR “Luigi Luca Cavalli-Sforza”, via Abbiategrasso 207, 27100 Pavia, Italy; (E.M.); (F.B.); (M.K.); (E.Z.); (S.G.); (G.T.); (A.G.); (A.M.); (S.B.); (F.d.d.F.); (S.F.); (S.S.)
| | - Giulia Tagliavini
- Institute of Molecular Genetics IGM-CNR “Luigi Luca Cavalli-Sforza”, via Abbiategrasso 207, 27100 Pavia, Italy; (E.M.); (F.B.); (M.K.); (E.Z.); (S.G.); (G.T.); (A.G.); (A.M.); (S.B.); (F.d.d.F.); (S.F.); (S.S.)
| | - Anna Garbelli
- Institute of Molecular Genetics IGM-CNR “Luigi Luca Cavalli-Sforza”, via Abbiategrasso 207, 27100 Pavia, Italy; (E.M.); (F.B.); (M.K.); (E.Z.); (S.G.); (G.T.); (A.G.); (A.M.); (S.B.); (F.d.d.F.); (S.F.); (S.S.)
| | - Antonio Maffia
- Institute of Molecular Genetics IGM-CNR “Luigi Luca Cavalli-Sforza”, via Abbiategrasso 207, 27100 Pavia, Italy; (E.M.); (F.B.); (M.K.); (E.Z.); (S.G.); (G.T.); (A.G.); (A.M.); (S.B.); (F.d.d.F.); (S.F.); (S.S.)
| | - Silvia Bione
- Institute of Molecular Genetics IGM-CNR “Luigi Luca Cavalli-Sforza”, via Abbiategrasso 207, 27100 Pavia, Italy; (E.M.); (F.B.); (M.K.); (E.Z.); (S.G.); (G.T.); (A.G.); (A.M.); (S.B.); (F.d.d.F.); (S.F.); (S.S.)
| | - Elena Ferrari
- Department of Molecular Mechanisms of Disease, University of Zürich-Irchel, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland; (E.F.); (U.H.)
| | - Fabrizio d’Adda di Fagagna
- Institute of Molecular Genetics IGM-CNR “Luigi Luca Cavalli-Sforza”, via Abbiategrasso 207, 27100 Pavia, Italy; (E.M.); (F.B.); (M.K.); (E.Z.); (S.G.); (G.T.); (A.G.); (A.M.); (S.B.); (F.d.d.F.); (S.F.); (S.S.)
- IFOM-The FIRC Institute of Molecular Oncology, 20139 Milan, Italy
| | - Sofia Francia
- Institute of Molecular Genetics IGM-CNR “Luigi Luca Cavalli-Sforza”, via Abbiategrasso 207, 27100 Pavia, Italy; (E.M.); (F.B.); (M.K.); (E.Z.); (S.G.); (G.T.); (A.G.); (A.M.); (S.B.); (F.d.d.F.); (S.F.); (S.S.)
| | - Simone Sabbioneda
- Institute of Molecular Genetics IGM-CNR “Luigi Luca Cavalli-Sforza”, via Abbiategrasso 207, 27100 Pavia, Italy; (E.M.); (F.B.); (M.K.); (E.Z.); (S.G.); (G.T.); (A.G.); (A.M.); (S.B.); (F.d.d.F.); (S.F.); (S.S.)
| | - Liuh-Yow Chen
- Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences, Frontiers in Genetics National Center of Competence in Research, Ecole Polytechnique Fédérale de Lausanne (EPFL), Station 19, CH-1015 Lausanne, Switzerland; (L.-Y.C.); (J.L.)
| | - Joachim Lingner
- Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences, Frontiers in Genetics National Center of Competence in Research, Ecole Polytechnique Fédérale de Lausanne (EPFL), Station 19, CH-1015 Lausanne, Switzerland; (L.-Y.C.); (J.L.)
| | - Valerie Bergoglio
- UMR1037 INSERM, Cancer Research Center of Toulouse, 2 Avenue Curien, 31037 Toulouse, France;
| | - Jean-Sébastien Hoffmann
- Laboratoire d’Excellence Toulouse Cancer (TOUCAN), Laboratoire de Pathologie, Institut Universitaire du Cancer-Toulouse, Oncopole, 1 Avenue Irène-Joliot-Curie, 31059 Toulouse, France;
| | - Ulrich Hübscher
- Department of Molecular Mechanisms of Disease, University of Zürich-Irchel, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland; (E.F.); (U.H.)
| | - Emmanuele Crespan
- Institute of Molecular Genetics IGM-CNR “Luigi Luca Cavalli-Sforza”, via Abbiategrasso 207, 27100 Pavia, Italy; (E.M.); (F.B.); (M.K.); (E.Z.); (S.G.); (G.T.); (A.G.); (A.M.); (S.B.); (F.d.d.F.); (S.F.); (S.S.)
- Correspondence: (E.C.); (G.M.)
| | - Giovanni Maga
- Institute of Molecular Genetics IGM-CNR “Luigi Luca Cavalli-Sforza”, via Abbiategrasso 207, 27100 Pavia, Italy; (E.M.); (F.B.); (M.K.); (E.Z.); (S.G.); (G.T.); (A.G.); (A.M.); (S.B.); (F.d.d.F.); (S.F.); (S.S.)
- Correspondence: (E.C.); (G.M.)
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34
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Engin AB, Engin A. The Connection Between Cell Fate and Telomere. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2021; 1275:71-100. [PMID: 33539012 DOI: 10.1007/978-3-030-49844-3_3] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Abolition of telomerase activity results in telomere shortening, a process that eventually destabilizes the ends of chromosomes, leading to genomic instability and cell growth arrest or death. Telomere shortening leads to the attainment of the "Hayflick limit", and the transition of cells to state of senescence. If senescence is bypassed, cells undergo crisis through loss of checkpoints. This process causes massive cell death concomitant with further telomere shortening and spontaneous telomere fusions. In functional telomere of mammalian cells, DNA contains double-stranded tandem repeats of TTAGGG. The Shelterin complex, which is composed of six different proteins, is required for the regulation of telomere length and stability in cells. Telomere protection by telomeric repeat binding protein 2 (TRF2) is dependent on DNA damage response (DDR) inhibition via formation of T-loop structures. Many protein kinases contribute to the DDR activated cell cycle checkpoint pathways, and prevent DNA replication until damaged DNA is repaired. Thereby, the connection between cell fate and telomere length-associated telomerase activity is regulated by multiple protein kinase activities. Contrarily, inactivation of DNA damage checkpoint protein kinases in senescent cells can restore cell-cycle progression into S phase. Therefore, telomere-initiated senescence is a DNA damage checkpoint response that is activated with a direct contribution from dysfunctional telomeres. In this review, in addition to the above mentioned, the choice of main repair pathways, which comprise non-homologous end joining and homologous recombination in telomere uncapping telomere dysfunctions, are discussed.
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Affiliation(s)
- Ayse Basak Engin
- Department of Toxicology, Faculty of Pharmacy, Gazi University, Ankara, Turkey.
| | - Atilla Engin
- Department of General Surgery, Faculty of Medicine, Gazi University, Ankara, Turkey
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Abstract
In this perspective, we introduce shelterin and the mechanisms of ATM activation and NHEJ at telomeres, before discussing the following questions: How are t-loops proposed to protect chromosome ends and what is the evidence for this model? Can other models explain how TRF2 mediates end protection? Could t-loops be pathological structures? How is end protection achieved in pluripotent cells? What do the insights into telomere end protection in pluripotent cells mean for the t-loop model of end protection? Why might different cell states have evolved different mechanisms of end protection? Finally, we offer support for an updated t-loop model of end protection, suggesting that the data is supportive of a critical role for t-loops in protecting chromosome ends from NHEJ and ATM activation, but that other mechanisms are involved. Finally, we propose that t-loops are likely dynamic, rather than static, structures.
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Affiliation(s)
- Phil Ruis
- The Francis Crick Institute, London NW1 1AT, United Kingdom
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36
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Yu EY, Zahid SS, Ganduri S, Sutherland JH, Hsu M, Holloman WK, Lue NF. Structurally distinct telomere-binding proteins in Ustilago maydis execute non-overlapping functions in telomere replication, recombination, and protection. Commun Biol 2020; 3:777. [PMID: 33328546 PMCID: PMC7744550 DOI: 10.1038/s42003-020-01505-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Accepted: 11/20/2020] [Indexed: 11/09/2022] Open
Abstract
Duplex telomere binding proteins exhibit considerable structural and functional diversity in fungi. Herein we interrogate the activities and functions of two Myb-containing, duplex telomere repeat-binding factors in Ustilago maydis, a basidiomycete that is evolutionarily distant from the standard fungi. These two telomere-binding proteins, UmTay1 and UmTrf2, despite having distinct domain structures, exhibit comparable affinities and sequence specificity for the canonical telomere repeats. UmTay1 specializes in promoting telomere replication and an ALT-like pathway, most likely by modulating the helicase activity of Blm. UmTrf2, in contrast, is critical for telomere protection; transcriptional repression of Umtrf2 leads to severe growth defects and profound telomere aberrations. Comparative analysis of UmTay1 homologs in different phyla reveals broad functional diversity for this protein family and provides a case study for how DNA-binding proteins can acquire and lose functions at various chromosomal locations. Our findings also point to stimulatory effect of telomere protein on ALT in Ustilago maydis that may be conserved in other systems.
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Affiliation(s)
- Eun Young Yu
- Department of Microbiology & Immunology, W. R. Hearst Microbiology Research Center, Weill Cornell Medicine, 1300 York Avenue, New York, NY, 10065, USA
| | - Syed S Zahid
- Department of Microbiology & Immunology, W. R. Hearst Microbiology Research Center, Weill Cornell Medicine, 1300 York Avenue, New York, NY, 10065, USA
| | - Swapna Ganduri
- Department of Microbiology & Immunology, W. R. Hearst Microbiology Research Center, Weill Cornell Medicine, 1300 York Avenue, New York, NY, 10065, USA
| | - Jeanette H Sutherland
- Department of Microbiology & Immunology, W. R. Hearst Microbiology Research Center, Weill Cornell Medicine, 1300 York Avenue, New York, NY, 10065, USA
| | - Min Hsu
- Department of Microbiology & Immunology, W. R. Hearst Microbiology Research Center, Weill Cornell Medicine, 1300 York Avenue, New York, NY, 10065, USA
| | - William K Holloman
- Department of Microbiology & Immunology, W. R. Hearst Microbiology Research Center, Weill Cornell Medicine, 1300 York Avenue, New York, NY, 10065, USA
| | - Neal F Lue
- Department of Microbiology & Immunology, W. R. Hearst Microbiology Research Center, Weill Cornell Medicine, 1300 York Avenue, New York, NY, 10065, USA. .,Sandra and Edward Meyer Cancer Center, Weill Cornell Medicine, 1300 York Avenue, New York, NY, 10065, USA.
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37
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Hoang SM, Kaminski N, Bhargava R, Barroso-González J, Lynskey ML, García-Expósito L, Roncaioli JL, Wondisford AR, Wallace CT, Watkins SC, James DI, Waddell ID, Ogilvie D, Smith KM, da Veiga Leprevost F, Mellacharevu D, Nesvizhskii AI, Li J, Ray-Gallet D, Sobol RW, Almouzni G, O'Sullivan RJ. Regulation of ALT-associated homology-directed repair by polyADP-ribosylation. Nat Struct Mol Biol 2020; 27:1152-1164. [PMID: 33046907 PMCID: PMC7809635 DOI: 10.1038/s41594-020-0512-7] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Accepted: 08/27/2020] [Indexed: 12/22/2022]
Abstract
The synthesis of poly(ADP-ribose) (PAR) reconfigures the local chromatin environment and recruits DNA-repair complexes to damaged chromatin. PAR degradation by poly(ADP-ribose) glycohydrolase (PARG) is essential for progression and completion of DNA repair. Here, we show that inhibition of PARG disrupts homology-directed repair (HDR) mechanisms that underpin alternative lengthening of telomeres (ALT). Proteomic analyses uncover a new role for poly(ADP-ribosyl)ation (PARylation) in regulating the chromatin-assembly factor HIRA in ALT cancer cells. We show that HIRA is enriched at telomeres during the G2 phase and is required for histone H3.3 deposition and telomere DNA synthesis. Depletion of HIRA elicits systemic death of ALT cancer cells that is mitigated by re-expression of ATRX, a protein that is frequently inactivated in ALT tumors. We propose that PARylation enables HIRA to fulfill its essential role in the adaptive response to ATRX deficiency that pervades ALT cancers.
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Affiliation(s)
- Song My Hoang
- Department of Pharmacology and Chemical Biology, UPMC Hillman Cancer Center, University of Pittsburgh, Pittsburgh, PA, USA
| | - Nicole Kaminski
- Department of Pharmacology and Chemical Biology, UPMC Hillman Cancer Center, University of Pittsburgh, Pittsburgh, PA, USA
| | - Ragini Bhargava
- Department of Pharmacology and Chemical Biology, UPMC Hillman Cancer Center, University of Pittsburgh, Pittsburgh, PA, USA
| | - Jonathan Barroso-González
- Department of Pharmacology and Chemical Biology, UPMC Hillman Cancer Center, University of Pittsburgh, Pittsburgh, PA, USA
| | - Michelle L Lynskey
- Department of Pharmacology and Chemical Biology, UPMC Hillman Cancer Center, University of Pittsburgh, Pittsburgh, PA, USA
| | - Laura García-Expósito
- Department of Pharmacology and Chemical Biology, UPMC Hillman Cancer Center, University of Pittsburgh, Pittsburgh, PA, USA
| | - Justin L Roncaioli
- Department of Pharmacology and Chemical Biology, UPMC Hillman Cancer Center, University of Pittsburgh, Pittsburgh, PA, USA
| | - Anne R Wondisford
- Department of Pharmacology and Chemical Biology, UPMC Hillman Cancer Center, University of Pittsburgh, Pittsburgh, PA, USA
| | - Callen T Wallace
- Department of Cell Biology, UPMC Hillman Cancer Center, University of Pittsburgh, Pittsburgh, PA, USA
| | - Simon C Watkins
- Department of Cell Biology, UPMC Hillman Cancer Center, University of Pittsburgh, Pittsburgh, PA, USA
| | - Dominic I James
- Drug Discovery Unit, Cancer Research UK Manchester Institute, The University of Manchester, Manchester, Macclesfield, UK
| | - Ian D Waddell
- Drug Discovery Unit, Cancer Research UK Manchester Institute, The University of Manchester, Manchester, Macclesfield, UK
| | - Donald Ogilvie
- Drug Discovery Unit, Cancer Research UK Manchester Institute, The University of Manchester, Manchester, Macclesfield, UK
| | - Kate M Smith
- Drug Discovery Unit, Cancer Research UK Manchester Institute, The University of Manchester, Manchester, Macclesfield, UK
| | | | | | - Alexey I Nesvizhskii
- Department of Pathology, University of Michigan, Ann Arbor, MI, USA
- Department of Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, MI, USA
| | - Jianfeng Li
- Department of Pharmacology and the Mitchell Cancer Institute, University of South Alabama, Mobile, AL, USA
| | - Dominique Ray-Gallet
- Institut Curie, PSL Research University, CNRS, Sorbonne Université, Nuclear Dynamics Unit, Equipe Labellisée, Ligue contre le Cancer, Paris, France
| | - Robert W Sobol
- Department of Pharmacology and the Mitchell Cancer Institute, University of South Alabama, Mobile, AL, USA
| | - Genevieve Almouzni
- Institut Curie, PSL Research University, CNRS, Sorbonne Université, Nuclear Dynamics Unit, Equipe Labellisée, Ligue contre le Cancer, Paris, France
| | - Roderick J O'Sullivan
- Department of Pharmacology and Chemical Biology, UPMC Hillman Cancer Center, University of Pittsburgh, Pittsburgh, PA, USA.
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Ahmed W, Lingner J. PRDX1 Counteracts Catastrophic Telomeric Cleavage Events That Are Triggered by DNA Repair Activities Post Oxidative Damage. Cell Rep 2020; 33:108347. [DOI: 10.1016/j.celrep.2020.108347] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 08/26/2020] [Accepted: 10/13/2020] [Indexed: 01/03/2023] Open
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Replication stress conferred by POT1 dysfunction promotes telomere relocalization to the nuclear pore. Genes Dev 2020; 34:1619-1636. [PMID: 33122293 PMCID: PMC7706707 DOI: 10.1101/gad.337287.120] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Accepted: 09/21/2020] [Indexed: 12/31/2022]
Abstract
In this study, Pinzaru et al. set out to uncover the pathways that enable the proliferation of cells expressing cancer-associated POT1 mutations. Using complementary genetic and proteomic approaches, the authors identify a conserved function for the NPC in resolving replication defects at telomere loci. Mutations in the telomere-binding protein POT1 are associated with solid tumors and leukemias. POT1 alterations cause rapid telomere elongation, ATR kinase activation, telomere fragility, and accelerated tumor development. Here, we define the impact of mutant POT1 alleles through complementary genetic and proteomic approaches based on CRISPR interference and biotin-based proximity labeling, respectively. These screens reveal that replication stress is a major vulnerability in cells expressing mutant POT1, which manifests as increased telomere mitotic DNA synthesis at telomeres. Our study also unveils a role for the nuclear pore complex in resolving replication defects at telomeres. Depletion of nuclear pore complex subunits in the context of POT1 dysfunction increases DNA damage signaling, telomere fragility and sister chromatid exchanges. Furthermore, we observed telomere repositioning to the nuclear periphery driven by nuclear F-actin polymerization in cells with POT1 mutations. In conclusion, our study establishes that relocalization of dysfunctional telomeres to the nuclear periphery is critical to preserve telomere repeat integrity.
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40
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Yang Z, Takai KK, Lovejoy CA, de Lange T. Break-induced replication promotes fragile telomere formation. Genes Dev 2020; 34:1392-1405. [PMID: 32883681 PMCID: PMC7528700 DOI: 10.1101/gad.328575.119] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Accepted: 08/04/2020] [Indexed: 12/16/2022]
Abstract
In this study, Yang et al. investigated how lagging-strand telomeres lacking TRF1 or BLM form fragile telomeres, structures that resemble common fragile sites (CFSs). They found that fragile telomeres in BLM-deficient cells involved double-strand break (DSB) formation by the SLX4/SLX1 nuclease, and the DSBs were repaired by POLD3/POLD4-dependent break-induced replication (BIR), resulting in fragile telomeres containing conservatively replicated DNA. TRF1 facilitates the replication of telomeric DNA in part by recruiting the BLM helicase, which can resolve G-quadruplexes on the lagging-strand template. Lagging-strand telomeres lacking TRF1 or BLM form fragile telomeres—structures that resemble common fragile sites (CFSs)—but how they are formed is not known. We report that analogous to CFSs, fragile telomeres in BLM-deficient cells involved double-strand break (DSB) formation, in this case by the SLX4/SLX1 nuclease. The DSBs were repaired by POLD3/POLD4-dependent break-induced replication (BIR), resulting in fragile telomeres containing conservatively replicated DNA. BIR also promoted fragile telomere formation in cells with FokI-induced telomeric DSBs and in alternative lengthening of telomeres (ALT) cells, which have spontaneous telomeric damage. BIR of telomeric DSBs competed with PARP1-, LIG3-, and XPF-dependent alternative nonhomologous end joining (alt-NHEJ), which did not generate fragile telomeres. Collectively, these findings indicate that fragile telomeres can arise from BIR-mediated repair of telomeric DSBs.
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Affiliation(s)
- Zhe Yang
- Laboratory for Cell Biology and Genetics, Rockefeller University; New York 10021, USA
| | - Kaori K Takai
- Laboratory for Cell Biology and Genetics, Rockefeller University; New York 10021, USA
| | - Courtney A Lovejoy
- Laboratory for Cell Biology and Genetics, Rockefeller University; New York 10021, USA
| | - Titia de Lange
- Laboratory for Cell Biology and Genetics, Rockefeller University; New York 10021, USA
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41
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Yeh SJ, Chen SW, Chen BS. Investigation of the Genome-Wide Genetic and Epigenetic Networks for Drug Discovery Based on Systems Biology Approaches in Colorectal Cancer. Front Genet 2020; 11:117. [PMID: 32211020 PMCID: PMC7068214 DOI: 10.3389/fgene.2020.00117] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Accepted: 01/31/2020] [Indexed: 12/29/2022] Open
Abstract
Colorectal cancer (CRC) is the third most commonly diagnosed type of cancer worldwide. The mechanisms leading to the progression of CRC are involved in both genetic and epigenetic regulations. In this study, we applied systems biology methods to identify potential biomarkers and conduct drug discovery in a computational approach. Using big database mining, we constructed a candidate protein-protein interaction network and a candidate gene regulatory network, combining them into a genome-wide genetic and epigenetic network (GWGEN). With the assistance of system identification and model selection approaches, we obtain real GWGENs for early-stage, mid-stage, and late-stage CRC. Subsequently, we extracted core GWGENs for each stage of CRC from their real GWGENs through a principal network projection method, and projected them to the Kyoto Encyclopedia of Genes and Genomes pathways for further analysis. Finally, we compared these core pathways resulting in different molecular mechanisms in each stage of CRC and identified carcinogenic biomarkers for the design of multiple-molecule drugs to prevent the progression of CRC. Based on the identified gene expression signatures, we suggested potential compounds combined with known CRC drugs to prevent the progression of CRC with querying Connectivity Map (CMap).
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Affiliation(s)
- Shan-Ju Yeh
- Laboratory of Automatic Control, Signaling Processing and Systems Biology, Department of Electrical Engineering, National Tsing Hua University, Hsinchu, Taiwan.,Department of Pediatrics and Human Development, College of Human Medicine, Michigan State University, Grand Rapids, MI, United States
| | - Shuo-Wei Chen
- Laboratory of Automatic Control, Signaling Processing and Systems Biology, Department of Electrical Engineering, National Tsing Hua University, Hsinchu, Taiwan
| | - Bor-Sen Chen
- Laboratory of Automatic Control, Signaling Processing and Systems Biology, Department of Electrical Engineering, National Tsing Hua University, Hsinchu, Taiwan
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42
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Chi X, Li Y, Qiu X. V(D)J recombination, somatic hypermutation and class switch recombination of immunoglobulins: mechanism and regulation. Immunology 2020; 160:233-247. [PMID: 32031242 DOI: 10.1111/imm.13176] [Citation(s) in RCA: 116] [Impact Index Per Article: 29.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2019] [Revised: 12/30/2019] [Accepted: 01/08/2020] [Indexed: 02/06/2023] Open
Abstract
Immunoglobulins emerging from B lymphocytes and capable of recognizing almost all kinds of antigens owing to the extreme diversity of their antigen-binding portions, known as variable (V) regions, play an important role in immune responses. The exons encoding the V regions are known as V (variable), D (diversity), or J (joining) genes. V, D, J segments exist as multiple copy arrays on the chromosome. The recombination of the V(D)J gene is the key mechanism to produce antibody diversity. The recombinational process, including randomly choosing a pair of V, D, J segments, introducing double-strand breaks adjacent to each segment, deleting (or inverting in some cases) the intervening DNA and ligating the segments together, is defined as V(D)J recombination, which contributes to surprising immunoglobulin diversity in vertebrate immune systems. To enhance both the ability of immunoglobulins to recognize and bind to foreign antigens and the effector capacities of the expressed antibodies, naive B cells will undergo class switching recombination (CSR) and somatic hypermutation (SHM). However, the genetics mechanisms of V(D)J recombination, CSR and SHM are not clear. In this review, we summarize the major progress in mechanism studies of immunoglobulin V(D)J gene recombination and CSR as well as SHM, and their regulatory mechanisms.
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Affiliation(s)
- Xiying Chi
- Department of Immunology, School of Basic Medical Sciences, Peking University, Beijing, China.,NHC Key Laboratory of Medical Immunology, Peking University, Beijing, China
| | - Yue Li
- Department of Immunology, School of Basic Medical Sciences, Peking University, Beijing, China.,NHC Key Laboratory of Medical Immunology, Peking University, Beijing, China
| | - Xiaoyan Qiu
- Department of Immunology, School of Basic Medical Sciences, Peking University, Beijing, China.,NHC Key Laboratory of Medical Immunology, Peking University, Beijing, China
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43
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Vítor AC, Huertas P, Legube G, de Almeida SF. Studying DNA Double-Strand Break Repair: An Ever-Growing Toolbox. Front Mol Biosci 2020; 7:24. [PMID: 32154266 PMCID: PMC7047327 DOI: 10.3389/fmolb.2020.00024] [Citation(s) in RCA: 87] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Accepted: 02/04/2020] [Indexed: 12/29/2022] Open
Abstract
To ward off against the catastrophic consequences of persistent DNA double-strand breaks (DSBs), eukaryotic cells have developed a set of complex signaling networks that detect these DNA lesions, orchestrate cell cycle checkpoints and ultimately lead to their repair. Collectively, these signaling networks comprise the DNA damage response (DDR). The current knowledge of the molecular determinants and mechanistic details of the DDR owes greatly to the continuous development of ground-breaking experimental tools that couple the controlled induction of DSBs at distinct genomic positions with assays and reporters to investigate DNA repair pathways, their impact on other DNA-templated processes and the specific contribution of the chromatin environment. In this review, we present these tools, discuss their pros and cons and illustrate their contribution to our current understanding of the DDR.
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Affiliation(s)
- Alexandra C Vítor
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina da Universidade de Lisboa, Lisbon, Portugal
| | - Pablo Huertas
- Department of Genetics, University of Seville, Seville, Spain.,Centro Andaluz de Biología Molecular y Medicina Regenerativa-CABIMER, Universidad de Sevilla-CSIC-Universidad Pablo de Olavide, Seville, Spain
| | - Gaëlle Legube
- LBCMCP, Centre de Biologie Integrative (CBI), CNRS, Université de Toulouse, Toulouse, France
| | - Sérgio F de Almeida
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina da Universidade de Lisboa, Lisbon, Portugal
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44
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Brambati A, Barry RM, Sfeir A. DNA polymerase theta (Polθ) - an error-prone polymerase necessary for genome stability. Curr Opin Genet Dev 2020; 60:119-126. [PMID: 32302896 PMCID: PMC7230004 DOI: 10.1016/j.gde.2020.02.017] [Citation(s) in RCA: 50] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Revised: 02/13/2020] [Accepted: 02/14/2020] [Indexed: 12/21/2022]
Abstract
Mammalian cells have evolved multiple pathways to repair DNA double strand breaks (DSBs) and ensure genome stability. In addition to non-homologous end-joining (NHEJ) and homologous recombination (HR), cells evolved an error-prone repair pathway termed microhomology-mediated end joining (MMEJ). The mutagenic outcome of MMEJ derives from the activity of DNA polymerase theta (Polθ) - a multidomain enzyme that is minimally expressed in normal tissue but overexpressed in tumors. Polθ expression is particularly crucial for the proliferation of HR deficient cancer cells. As a result, this mutagenic repair emerged as an attractive target for cancer therapy, and inhibitors are currently in pre-clinical development. Here, we review the multifunctionality of this enigmatic polymerase, focusing on its role during DSB repair in mammalian cells and its impact on cancer genomes.
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Affiliation(s)
- Alessandra Brambati
- Skirball Institute of Biomolecular Medicine, Department of Cell Biology, NYU School of Medicine, New York, NY 10016, USA
| | - Raymond Mario Barry
- Skirball Institute of Biomolecular Medicine, Department of Cell Biology, NYU School of Medicine, New York, NY 10016, USA
| | - Agnel Sfeir
- Skirball Institute of Biomolecular Medicine, Department of Cell Biology, NYU School of Medicine, New York, NY 10016, USA.
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45
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Wilk A, Hayat F, Cunningham R, Li J, Garavaglia S, Zamani L, Ferraris DM, Sykora P, Andrews J, Clark J, Davis A, Chaloin L, Rizzi M, Migaud M, Sobol RW. Extracellular NAD + enhances PARP-dependent DNA repair capacity independently of CD73 activity. Sci Rep 2020; 10:651. [PMID: 31959836 PMCID: PMC6971268 DOI: 10.1038/s41598-020-57506-9] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Accepted: 12/29/2019] [Indexed: 02/06/2023] Open
Abstract
Changes in nicotinamide adenine dinucleotide (NAD+) levels that compromise mitochondrial function trigger release of DNA damaging reactive oxygen species. NAD+ levels also affect DNA repair capacity as NAD+ is a substrate for PARP-enzymes (mono/poly-ADP-ribosylation) and sirtuins (deacetylation). The ecto-5′-nucleotidase CD73, an ectoenzyme highly expressed in cancer, is suggested to regulate intracellular NAD+ levels by processing NAD+ and its bio-precursor, nicotinamide mononucleotide (NMN), from tumor microenvironments, thereby enhancing tumor DNA repair capacity and chemotherapy resistance. We therefore investigated whether expression of CD73 impacts intracellular NAD+ content and NAD+-dependent DNA repair capacity. Reduced intracellular NAD+ levels suppressed recruitment of the DNA repair protein XRCC1 to sites of genomic DNA damage and impacted the amount of accumulated DNA damage. Further, decreased NAD+ reduced the capacity to repair DNA damage induced by DNA alkylating agents. Overall, reversal of these outcomes through NAD+ or NMN supplementation was independent of CD73. In opposition to its proposed role in extracellular NAD+ bioprocessing, we found that recombinant human CD73 only poorly processes NMN but not NAD+. A positive correlation between CD73 expression and intracellular NAD+ content could not be made as CD73 knockout human cells were efficient in generating intracellular NAD+ when supplemented with NAD+ or NMN.
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Affiliation(s)
- Anna Wilk
- Mitchell Cancer Institute, University of South Alabama, Mobile, AL, 36604, USA.,Department of Pharmacology, College of Medicine, University of South Alabama, Mobile, AL, 36604, USA
| | - Faisal Hayat
- Mitchell Cancer Institute, University of South Alabama, Mobile, AL, 36604, USA.,Department of Pharmacology, College of Medicine, University of South Alabama, Mobile, AL, 36604, USA
| | - Richard Cunningham
- Mitchell Cancer Institute, University of South Alabama, Mobile, AL, 36604, USA.,Department of Pharmacology, College of Medicine, University of South Alabama, Mobile, AL, 36604, USA
| | - Jianfeng Li
- Mitchell Cancer Institute, University of South Alabama, Mobile, AL, 36604, USA.,Department of Pharmacology, College of Medicine, University of South Alabama, Mobile, AL, 36604, USA
| | - Silvia Garavaglia
- Department of Pharmaceutical Sciences, University of Piemonte Orientale, Largo Donegani 2, 28100, Novara, Italy
| | - Leila Zamani
- Mitchell Cancer Institute, University of South Alabama, Mobile, AL, 36604, USA
| | - Davide M Ferraris
- Department of Pharmaceutical Sciences, University of Piemonte Orientale, Largo Donegani 2, 28100, Novara, Italy
| | - Peter Sykora
- Mitchell Cancer Institute, University of South Alabama, Mobile, AL, 36604, USA.,Amelia Technologies, 14676 Rothgeb Drive, Rockville, MD, 20850, USA
| | - Joel Andrews
- Mitchell Cancer Institute, University of South Alabama, Mobile, AL, 36604, USA
| | - Jennifer Clark
- Mitchell Cancer Institute, University of South Alabama, Mobile, AL, 36604, USA.,Department of Pharmacology, College of Medicine, University of South Alabama, Mobile, AL, 36604, USA
| | - Amanda Davis
- Mitchell Cancer Institute, University of South Alabama, Mobile, AL, 36604, USA
| | - Laurent Chaloin
- Institut de Recherche en Infectiologie de Montpellier (IRIM), Université de Montpellier, CNRS, 34293, Montpellier, France
| | - Menico Rizzi
- Department of Pharmaceutical Sciences, University of Piemonte Orientale, Largo Donegani 2, 28100, Novara, Italy
| | - Marie Migaud
- Mitchell Cancer Institute, University of South Alabama, Mobile, AL, 36604, USA.,Department of Pharmacology, College of Medicine, University of South Alabama, Mobile, AL, 36604, USA
| | - Robert W Sobol
- Mitchell Cancer Institute, University of South Alabama, Mobile, AL, 36604, USA. .,Department of Pharmacology, College of Medicine, University of South Alabama, Mobile, AL, 36604, USA.
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46
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Lovejoy CA, Takai K, Huh MS, Picketts DJ, de Lange T. ATRX affects the repair of telomeric DSBs by promoting cohesion and a DAXX-dependent activity. PLoS Biol 2020; 18:e3000594. [PMID: 31895940 PMCID: PMC6959610 DOI: 10.1371/journal.pbio.3000594] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Revised: 01/14/2020] [Accepted: 12/19/2019] [Indexed: 12/20/2022] Open
Abstract
Alpha thalassemia/mental retardation syndrome X-linked chromatin remodeler (ATRX), a DAXX (death domain-associated protein) interacting protein, is often lost in cells using the alternative lengthening of telomeres (ALT) pathway, but it is not known how ATRX loss leads to ALT. We report that ATRX deletion from mouse cells altered the repair of telomeric double-strand breaks (DSBs) and induced ALT-like phenotypes, including ALT-associated promyelocytic leukemia (PML) bodies (APBs), telomere sister chromatid exchanges (T-SCEs), and extrachromosomal telomeric signals (ECTSs). Mechanistically, we show that ATRX affects telomeric DSB repair by promoting cohesion of sister telomeres and that loss of ATRX in ALT cells results in diminished telomere cohesion. In addition, we document a role for DAXX in the repair of telomeric DSBs. Removal of telomeric cohesion in combination with DAXX deficiency recapitulates all telomeric DSB repair phenotypes associated with ATRX loss. The data reveal that ATRX has an effect on telomeric DSB repair and that this role involves both telomere cohesion and a DAXX-dependent pathway.
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Affiliation(s)
- Courtney A. Lovejoy
- Laboratory for Cell Biology and Genetics, The Rockefeller University, New York, New York, United States of America
| | - Kaori Takai
- Laboratory for Cell Biology and Genetics, The Rockefeller University, New York, New York, United States of America
| | - Michael S. Huh
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
| | - David J. Picketts
- Regenerative Medicine Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario, Canada
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario, Canada
| | - Titia de Lange
- Laboratory for Cell Biology and Genetics, The Rockefeller University, New York, New York, United States of America
- * E-mail:
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47
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G-quadruplex Structures Contribute to Differential Radiosensitivity of the Human Genome. iScience 2019; 21:288-307. [PMID: 31678912 PMCID: PMC6838516 DOI: 10.1016/j.isci.2019.10.033] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Revised: 06/12/2019] [Accepted: 10/16/2019] [Indexed: 02/04/2023] Open
Abstract
DNA, the fundamental unit of human cell, generally exists in Watson-Crick base-paired B-DNA form. Often, DNA folds into non-B forms, such as four-stranded G-quadruplexes. It is generally believed that ionizing radiation (IR) induces DNA strand-breaks in a random manner. Here, we show that regions of DNA enriched in G-quadruplex structures are less sensitive to IR compared with B-DNA in vitro and inside cells. Planar G-quartet of G4-DNA is shielded from IR-induced free radicals, unlike single- and double-stranded DNA. Whole-genome sequence analysis and real-time PCR reveal that genomic regions abundant in G4-DNA are protected from radiation-induced breaks and can be modulated by G4 stabilizers. Thus, our results reveal that formation of G4 structures contribute toward differential radiosensitivity of the human genome. G4 DNA contributes to genome-wide radioprotection and is modulated by G4 resolvases Radiation causes minimal damage at the G4 structures at telomeres Formation of G4 DNA contributes toward differential radiosensitivity of human genome Planar quartet of G4 DNA is shielded from IR-induced free radicals and thus DNA breaks
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48
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Abstract
Reactive oxygen species (ROS) play important roles in aging, inflammation, and cancer. Mitochondria are an important source of ROS; however, the spatiotemporal ROS events underlying oxidative cellular damage from dysfunctional mitochondria remain unresolved. To this end, we have developed and validated a chemoptogenetic approach that uses a mitochondrially targeted fluorogen-activating peptide (Mito-FAP) to deliver a photosensitizer MG-2I dye exclusively to this organelle. Light-mediated activation (660 nm) of the Mito-FAP-MG-2I complex led to a rapid loss of mitochondrial respiration, decreased electron transport chain complex activity, and mitochondrial fragmentation. Importantly, one round of singlet oxygen produced a persistent secondary wave of mitochondrial superoxide and hydrogen peroxide lasting for over 48 h after the initial insult. By following ROS intermediates, we were able to detect hydrogen peroxide in the nucleus through ratiometric analysis of the oxidation of nuclear cysteine residues. Despite mitochondrial DNA (mtDNA) damage and nuclear oxidative stress induced by dysfunctional mitochondria, there was a lack of gross nuclear DNA strand breaks and apoptosis. Targeted telomere analysis revealed fragile telomeres and telomere loss as well as 53BP1-positive telomere dysfunction-induced foci (TIFs), indicating that DNA double-strand breaks occurred exclusively in telomeres as a direct consequence of mitochondrial dysfunction. These telomere defects activated ataxia-telangiectasia mutated (ATM)-mediated DNA damage repair signaling. Furthermore, ATM inhibition exacerbated the Mito-FAP-induced mitochondrial dysfunction and sensitized cells to apoptotic cell death. This profound sensitivity of telomeres through hydrogen peroxide induced by dysregulated mitochondria reveals a crucial mechanism of telomere-mitochondria communication underlying the pathophysiological role of mitochondrial ROS in human diseases.
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49
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Transient induction of telomerase expression mediates senescence and reduces tumorigenesis in primary fibroblasts. Proc Natl Acad Sci U S A 2019; 116:18983-18993. [PMID: 31481614 PMCID: PMC6754593 DOI: 10.1073/pnas.1907199116] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Telomerase is an enzymatic ribonucleoprotein complex that acts as a reverse transcriptase in the elongation of telomeres. Telomerase activity is well documented in embryonic stem cells and the vast majority of tumor cells, but its role in somatic cells remains to be understood. Here, we report an unexpected function of telomerase during cellular senescence and tumorigenesis. We crossed Tert heterozygous knockout mice (mTert +/- ) for 26 generations, during which time there was progressive shortening of telomeres, and obtained primary skin fibroblasts from mTert +/+ and mTert -/- progeny of the 26th cross. As a consequence of insufficient telomerase activities in prior generations, both mTert +/+ and mTert -/- fibroblasts showed comparable and extremely short telomere length. However, mTert -/- cells approached cellular senescence faster and exhibited a significantly higher rate of malignant transformation than mTert +/+ cells. Furthermore, an evident up-regulation of telomerase reverse-transcriptase (TERT) expression was detected in mTert +/+ cells at the presenescence stage. Moreover, removal or down-regulation of TERT expression in mTert +/+ and human primary fibroblast cells via CRISPR/Cas9 or shRNA recapitulated mTert -/- phenotypes of accelerated senescence and transformation, and overexpression of TERT in mTert -/- cells rescued these phenotypes. Taking these data together, this study suggests that TERT has a previously underappreciated, protective role in buffering senescence stresses due to short, dysfunctional telomeres, and preventing malignant transformation.
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50
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X-rays Activate Telomeric Homologous Recombination Mediated Repair in Primary Cells. Cells 2019; 8:cells8070708. [PMID: 31336873 PMCID: PMC6678842 DOI: 10.3390/cells8070708] [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: 04/01/2019] [Revised: 06/27/2019] [Accepted: 07/06/2019] [Indexed: 12/31/2022] Open
Abstract
Cancer cells need to acquire telomere maintenance mechanisms in order to counteract progressive telomere shortening due to multiple rounds of replication. Most human tumors maintain their telomeres expressing telomerase whereas the remaining 15%–20% utilize the alternative lengthening of telomeres (ALT) pathway. Previous studies have demonstrated that ionizing radiations (IR) are able to modulate telomere lengths and to transiently induce some of the ALT-pathway hallmarks in normal primary fibroblasts. In the present study, we investigated the telomere length modulation kinetics, telomeric DNA damage induction, and the principal hallmarks of ALT over a period of 13 days in X-ray-exposed primary cells. Our results show that X-ray-treated cells primarily display telomere shortening and telomeric damage caused by persistent IR-induced oxidative stress. After initial telomere erosion, we observed a telomere elongation that was associated to the transient activation of a homologous recombination (HR) based mechanism, sharing several features with the ALT pathway observed in cancer cells. Data indicate that telomeric damage activates telomeric HR-mediated repair in primary cells. The characterization of HR-mediated telomere repair in normal cells may contribute to the understanding of the ALT pathway and to the identification of novel strategies in the treatment of ALT-positive cancers.
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