1
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Jones-Weinert C, Mainz L, Karlseder J. Telomere function and regulation from mouse models to human ageing and disease. Nat Rev Mol Cell Biol 2024:10.1038/s41580-024-00800-5. [PMID: 39614014 DOI: 10.1038/s41580-024-00800-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/16/2024] [Indexed: 12/01/2024]
Abstract
Telomeres protect the ends of chromosomes but shorten following cell division in the absence of telomerase activity. When telomeres become critically short or damaged, a DNA damage response is activated. Telomeres then become dysfunctional and trigger cellular senescence or death. Telomere shortening occurs with ageing and may contribute to associated maladies such as infertility, neurodegeneration, cancer, lung dysfunction and haematopoiesis disorders. Telomere dysfunction (sometimes without shortening) is associated with various diseases, known as telomere biology disorders (also known as telomeropathies). Telomere biology disorders include dyskeratosis congenita, Høyeraal-Hreidarsson syndrome, Coats plus syndrome and Revesz syndrome. Although mouse models have been invaluable in advancing telomere research, full recapitulation of human telomere-related diseases in mice has been challenging, owing to key differences between the species. In this Review, we discuss telomere protection, maintenance and damage. We highlight the differences between human and mouse telomere biology that may contribute to discrepancies between human diseases and mouse models. Finally, we discuss recent efforts to generate new 'humanized' mouse models to better model human telomere biology. A better understanding of the limitations of mouse telomere models will pave the road for more human-like models and further our understanding of telomere biology disorders, which will contribute towards the development of new therapies.
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Affiliation(s)
| | - Laura Mainz
- The Salk Institute for Biological Studies, La Jolla, CA, USA
| | - Jan Karlseder
- The Salk Institute for Biological Studies, La Jolla, CA, USA.
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2
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Douglas ME. How to write an ending: Telomere replication as a multistep process. DNA Repair (Amst) 2024; 144:103774. [PMID: 39426311 DOI: 10.1016/j.dnarep.2024.103774] [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: 07/12/2024] [Revised: 10/01/2024] [Accepted: 10/04/2024] [Indexed: 10/21/2024]
Abstract
Telomeres are protective nucleoprotein caps found at the natural ends of eukaryotic chromosomes and are crucial for the preservation of stable chromosomal structure. In cycling cells, telomeres are maintained by a multi-step process called telomere replication, which involves the eukaryotic replisome navigating a complex repetitive template tightly bound by specific proteins, before terminating at the chromosome end prior to a 5' resection step that generates a protective 3' overhang. In this review, we examine mechanistic aspects of the telomere replication process and consider how individual parts of this multistep event are integrated and coordinated with one-another.
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Affiliation(s)
- Max E Douglas
- Telomere Biology Laboratory, The Institute of Cancer Research, 237 Fulham Road, London SW3 6JB, UK.
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3
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Liang F, Rai R, Sodeinde T, Chang S. TRF2-RAP1 represses RAD51-dependent homology-directed telomere repair by promoting BLM-mediated D-loop unwinding and inhibiting BLM-DNA2-dependent 5'-end resection. Nucleic Acids Res 2024; 52:9695-9709. [PMID: 39082275 PMCID: PMC11381343 DOI: 10.1093/nar/gkae642] [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: 05/07/2024] [Revised: 06/26/2024] [Accepted: 07/12/2024] [Indexed: 09/10/2024] Open
Abstract
Inappropriate homology-directed repair (HDR) of telomeres results in catastrophic telomere loss and aberrant chromosome fusions, leading to genome instability. We have previously shown that the TRF2-RAP1 heterodimer protects telomeres from engaging in aberrant telomere HDR. Cells lacking the basic domain of TRF2 and functional RAP1 display HDR-mediated telomere clustering, resulting in the formation of ultrabright telomeres (UTs) and massive chromosome fusions. Using purified proteins, we uncover three distinct molecular pathways that the TRF2-RAP1 heterodimer utilizes to protect telomeres from engaging in aberrant HDR. We show mechanistically that TRF2-RAP1 inhibits RAD51-initiated telomeric D-loop formation. Both the TRF2 basic domain and RAP1-binding to TRF2 are required to block RAD51-mediated homology search. TRF2 recruits the BLM helicase to telomeres through its TRFH domain to promote BLM-mediated unwinding of telomere D-loops. In addition, TRF2-RAP1 inhibits BLM-DNA2-mediated 5' telomere end resection, preventing the generation of 3' single-stranded telomere overhangs necessary for RAD51-dependent HDR. Importantly, cells expressing BLM mutants unable to interact with TRF2 accumulate telomere D-loops and UTs. Our findings uncover distinct molecular mechanisms coordinated by TRF2-RAP1 to protect telomeres from engaging in aberrant HDR.
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Affiliation(s)
- Fengshan Liang
- Departments of Laboratory Medicine, Yale University School of Medicine, 330 Cedar St., New Haven, CT 06520, USA
| | - Rekha Rai
- Departments of Laboratory Medicine, Yale University School of Medicine, 330 Cedar St., New Haven, CT 06520, USA
| | - Tori Sodeinde
- Departments of Laboratory Medicine, Yale University School of Medicine, 330 Cedar St., New Haven, CT 06520, USA
| | - Sandy Chang
- Departments of Laboratory Medicine, Yale University School of Medicine, 330 Cedar St., New Haven, CT 06520, USA
- Pathology, Yale University School of Medicine, 330 Cedar St., New Haven, CT 06520, USA
- Molecular Biophysics and Biochemistry, Yale University School of Medicine, 330 Cedar St., New Haven, CT 06520, USA
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4
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Estrem B, Davis R, Wang J. End resection and telomere healing of DNA double-strand breaks during nematode programmed DNA elimination. Nucleic Acids Res 2024; 52:8913-8929. [PMID: 38953168 PMCID: PMC11347171 DOI: 10.1093/nar/gkae579] [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: 03/15/2024] [Revised: 05/24/2024] [Accepted: 06/24/2024] [Indexed: 07/03/2024] Open
Abstract
Most DNA double-strand breaks (DSBs) are harmful to genome integrity. However, some forms of DSBs are essential to biological processes, such as meiotic recombination and V(D)J recombination. DSBs are also required for programmed DNA elimination (PDE) in ciliates and nematodes. In nematodes, the DSBs are healed with telomere addition. While telomere addition sites have been well characterized, little is known regarding the DSBs that fragment nematode chromosomes. Here, we used embryos from the human and pig parasitic nematode Ascaris to characterize the DSBs. Using END-seq, we demonstrate that DSBs are introduced before mitosis, followed by extensive end resection. The resection profile is unique for each break site, and the resection generates 3'-overhangs before the addition of neotelomeres. Interestingly, telomere healing occurs much more frequently on retained DSB ends than on eliminated ends. This biased repair of the DSB ends may be due to the sequestration of the eliminated DNA into micronuclei, preventing neotelomere formation at their ends. Additional DNA breaks occur within the eliminated DNA in both Ascaris and Parascaris, ensuring chromosomal breakage and providing a fail-safe mechanism for PDE. Overall, our data indicate that telomere healing of DSBs is specific to the break sites responsible for nematode PDE.
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Affiliation(s)
- Brandon Estrem
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996, USA
| | - Richard E Davis
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Jianbin Wang
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996, USA
- UT-ORNL Graduate School of Genome Science and Technology, University of Tennessee, Knoxville, TN 37996, USA
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5
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Wentworth K, Nandakumar J. At the end, it is POT1 again: Phosphorylation allows human telomeric protein POT1 to recruit the C-rich strand end replication machinery. Mol Cell 2024; 84:2598-2600. [PMID: 39059369 PMCID: PMC11613731 DOI: 10.1016/j.molcel.2024.06.030] [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: 06/25/2024] [Revised: 06/25/2024] [Accepted: 06/25/2024] [Indexed: 07/28/2024]
Abstract
Recently in Cell, Cai et al.1 reported how phosphorylation of human shelterin protein POT1 allows it to recruit the telomeric C-rich strand replication machinery, providing mechanistic insights into an understudied area of telomere biology with implications for telomere biology disorders.
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Affiliation(s)
- Katherine Wentworth
- 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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6
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Cai SW, Takai H, Zaug AJ, Dilgen TC, Cech TR, Walz T, de Lange T. POT1 recruits and regulates CST-Polα/primase at human telomeres. Cell 2024; 187:3638-3651.e18. [PMID: 38838667 PMCID: PMC11246235 DOI: 10.1016/j.cell.2024.05.002] [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: 06/12/2023] [Revised: 03/12/2024] [Accepted: 05/01/2024] [Indexed: 06/07/2024]
Abstract
Telomere maintenance requires the extension of the G-rich telomeric repeat strand by telomerase and the fill-in synthesis of the C-rich strand by Polα/primase. At telomeres, Polα/primase is bound to Ctc1/Stn1/Ten1 (CST), a single-stranded DNA-binding complex. Like mutations in telomerase, mutations affecting CST-Polα/primase result in pathological telomere shortening and cause a telomere biology disorder, Coats plus (CP). We determined cryogenic electron microscopy structures of human CST bound to the shelterin heterodimer POT1/TPP1 that reveal how CST is recruited to telomeres by POT1. Our findings suggest that POT1 hinge phosphorylation is required for CST recruitment, and the complex is formed through conserved interactions involving several residues mutated in CP. Our structural and biochemical data suggest that phosphorylated POT1 holds CST-Polα/primase in an inactive, autoinhibited state until telomerase has extended the telomere ends. We propose that dephosphorylation of POT1 releases CST-Polα/primase into an active state that completes telomere replication through fill-in synthesis.
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Affiliation(s)
- Sarah W Cai
- Laboratory of Cell Biology and Genetics, The Rockefeller University, New York, NY 10065, USA; Laboratory of Molecular Electron Microscopy, The Rockefeller University, New York, NY 10065, USA
| | - Hiroyuki Takai
- Laboratory of Cell Biology and Genetics, The Rockefeller University, New York, NY 10065, USA
| | - Arthur J Zaug
- Department of Biochemistry, University of Colorado Boulder, Boulder, CO 80303, USA; BioFrontiers Institute, University of Colorado Boulder, Boulder, CO 80303, USA; Howard Hughes Medical Institute, University of Colorado Boulder, Boulder, CO 80303, USA
| | - Teague C Dilgen
- Laboratory of Cell Biology and Genetics, The Rockefeller University, New York, NY 10065, USA
| | - Thomas R Cech
- Department of Biochemistry, University of Colorado Boulder, Boulder, CO 80303, USA; BioFrontiers Institute, University of Colorado Boulder, Boulder, CO 80303, USA; Howard Hughes Medical Institute, University of Colorado Boulder, Boulder, CO 80303, USA
| | - Thomas Walz
- Laboratory of Molecular Electron Microscopy, The Rockefeller University, New York, NY 10065, USA.
| | - Titia de Lange
- Laboratory of Cell Biology and Genetics, The Rockefeller University, New York, NY 10065, USA.
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7
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Stuart A, de Lange T. Replicative senescence is ATM driven, reversible, and accelerated by hyperactivation of ATM at normoxia. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.24.600514. [PMID: 38979390 PMCID: PMC11230194 DOI: 10.1101/2024.06.24.600514] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/10/2024]
Abstract
Programmed telomere shortening limits tumorigenesis through the induction of replicative senescence. Here we address three long-standing questions concerning senescence. First, we show that the ATM kinase is solely responsible for the induction of replicative senescence. Senescence was delayed by ATM inhibition (ATMi) or overexpression of TRF2, the shelterin subunit dedicated to ATM repression. In contrast, there was no evidence for ATR signaling contributing to replicative senescence even when ATMi was combined with ATR inhibition. Second, we show ATMi can induce apparently normal cell divisions in a subset of senescent cells, indicating that senescence can be reversed. Third, we show that the extended replicative life span at low (physiological) oxygen is due to diminished ATM activity. At low oxygen, cells show a decreased ATM response to dysfunctional telomeres and genome-wide DSBs compared to 20% oxygen. As this effect could be reversed by NAC, the attenuated response of ATM to critically short telomeres and the resulting extended life span at low oxygen is likely due to ROS-induced formation of cysteine disulfide-bridges that crosslink ATM dimers into a form that is not activated by DSBs. These findings show how primary human cells detect shortened telomeres and reveal the molecular mechanism underlying the telomere tumor suppressor pathway.
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Affiliation(s)
- Alexander Stuart
- Laboratory for Cell Biology and Genetics, Rockefeller University, New York, USA
| | - Titia de Lange
- Laboratory for Cell Biology and Genetics, Rockefeller University, New York, USA
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8
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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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9
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Bories C, Lejour T, Adolphe F, Kermasson L, Couvé S, Tanguy L, Luszczewska G, Watzky M, Poillerat V, Garnier P, Groisman R, Ferlicot S, Richard S, Saparbaev M, Revy P, Gad S, Renaud F. DCLRE1B/Apollo germline mutations associated with renal cell carcinoma impair telomere protection. Biochim Biophys Acta Mol Basis Dis 2024; 1870:167107. [PMID: 38430974 DOI: 10.1016/j.bbadis.2024.167107] [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: 07/05/2023] [Revised: 02/14/2024] [Accepted: 02/25/2024] [Indexed: 03/05/2024]
Abstract
Hereditary renal cell carcinoma (RCC) is caused by germline mutations in a subset of genes, including VHL, MET, FLCN, and FH. However, many familial RCC cases do not harbor mutations in the known predisposition genes. Using Whole Exome Sequencing, we identified two germline missense variants in the DCLRE1B/Apollo gene (ApolloN246I and ApolloY273H) in two unrelated families with several RCC cases. Apollo encodes an exonuclease involved in DNA Damage Response and Repair (DDRR) and telomere integrity. We characterized these two functions in the human renal epithelial cell line HKC8. The decrease or inhibition of Apollo expression sensitizes these cells to DNA interstrand crosslink damage (ICLs). HKC8 Apollo-/- cells appear defective in the DDRR and present an accumulation of telomere damage. Wild-type and mutated Apollo forms could interact with TRF2, a shelterin protein involved in telomere protection. However, only ApolloWT can rescue the telomere damage in HKC8 Apollo-/- cells. Our results strongly suggest that ApolloN246I and ApolloY273H are loss-of-function mutants that cause impaired telomere integrity and could lead to genomic instability. Altogether, our results suggest that mutations in Apollo could induce renal oncogenesis.
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Affiliation(s)
- Charlie Bories
- EPHE, PSL Université, Paris, France; UMR 9019 CNRS, Gustave Roussy, Université Paris-Saclay, 114 rue Edouard Vaillant, Villejuif 94800, France
| | - Thomas Lejour
- EPHE, PSL Université, Paris, France; UMR 9019 CNRS, Gustave Roussy, Université Paris-Saclay, 114 rue Edouard Vaillant, Villejuif 94800, France
| | - Florine Adolphe
- EPHE, PSL Université, Paris, France; UMR 9019 CNRS, Gustave Roussy, Université Paris-Saclay, 114 rue Edouard Vaillant, Villejuif 94800, France
| | - Laëtitia Kermasson
- Laboratory of Genome Dynamics in the Immune System, Laboratoire labellisé Ligue Nationale contre le Cancer, INSERM UMR 1163, Université de Paris, Imagine Institute, Paris, France
| | - Sophie Couvé
- EPHE, PSL Université, Paris, France; UMR 9019 CNRS, Gustave Roussy, Université Paris-Saclay, 114 rue Edouard Vaillant, Villejuif 94800, France
| | - Laura Tanguy
- EPHE, PSL Université, Paris, France; UMR 9019 CNRS, Gustave Roussy, Université Paris-Saclay, 114 rue Edouard Vaillant, Villejuif 94800, France
| | - Gabriela Luszczewska
- EPHE, PSL Université, Paris, France; UMR 9019 CNRS, Gustave Roussy, Université Paris-Saclay, 114 rue Edouard Vaillant, Villejuif 94800, France
| | - Manon Watzky
- EPHE, PSL Université, Paris, France; UMR 9019 CNRS, Gustave Roussy, Université Paris-Saclay, 114 rue Edouard Vaillant, Villejuif 94800, France
| | - Victoria Poillerat
- EPHE, PSL Université, Paris, France; UMR 9019 CNRS, Gustave Roussy, Université Paris-Saclay, 114 rue Edouard Vaillant, Villejuif 94800, France
| | - Pauline Garnier
- EPHE, PSL Université, Paris, France; UMR 9019 CNRS, Gustave Roussy, Université Paris-Saclay, 114 rue Edouard Vaillant, Villejuif 94800, France
| | - Regina Groisman
- UMR 9019 CNRS, Gustave Roussy, Université Paris-Saclay, 114 rue Edouard Vaillant, Villejuif 94800, France
| | - Sophie Ferlicot
- UMR 9019 CNRS, Gustave Roussy, Université Paris-Saclay, 114 rue Edouard Vaillant, Villejuif 94800, France; Département de Pathologie, AP-HP, Université Paris-Saclay, Hôpital de Bicêtre, Le Kremlin-Bicêtre, France
| | - Stéphane Richard
- EPHE, PSL Université, Paris, France; UMR 9019 CNRS, Gustave Roussy, Université Paris-Saclay, 114 rue Edouard Vaillant, Villejuif 94800, France; Réseau National de Référence pour Cancers Rares de l'Adulte PREDIR labellisé par l'INCa, Hôpital de Bicêtre, AP-HP, et Service d'Urologie, Le Kremlin-Bicêtre, France
| | - Murat Saparbaev
- UMR 9019 CNRS, Gustave Roussy, Université Paris-Saclay, 114 rue Edouard Vaillant, Villejuif 94800, France
| | - Patrick Revy
- Laboratory of Genome Dynamics in the Immune System, Laboratoire labellisé Ligue Nationale contre le Cancer, INSERM UMR 1163, Université de Paris, Imagine Institute, Paris, France
| | - Sophie Gad
- EPHE, PSL Université, Paris, France; UMR 9019 CNRS, Gustave Roussy, Université Paris-Saclay, 114 rue Edouard Vaillant, Villejuif 94800, France
| | - Flore Renaud
- EPHE, PSL Université, Paris, France; UMR 9019 CNRS, Gustave Roussy, Université Paris-Saclay, 114 rue Edouard Vaillant, Villejuif 94800, France.
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10
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Takai H, Aria V, Borges P, Yeeles JTP, de Lange T. CST-polymerase α-primase solves a second telomere end-replication problem. Nature 2024; 627:664-670. [PMID: 38418884 PMCID: PMC11160940 DOI: 10.1038/s41586-024-07137-1] [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: 07/26/2023] [Accepted: 01/30/2024] [Indexed: 03/02/2024]
Abstract
Telomerase adds G-rich telomeric repeats to the 3' ends of telomeres1, counteracting telomere shortening caused by loss of telomeric 3' overhangs during leading-strand DNA synthesis ('the end-replication problem'2). Here we report a second end-replication problem that originates from the incomplete duplication of the C-rich telomeric repeat strand (C-strand) by lagging-strand DNA synthesis. This problem is resolved by fill-in synthesis mediated by polymerase α-primase bound to Ctc1-Stn1-Ten1 (CST-Polα-primase). In vitro, priming for lagging-strand DNA replication does not occur on the 3' overhang and lagging-strand synthesis stops in a zone of approximately 150 nucleotides (nt) more than 26 nt from the end of the template. Consistent with the in vitro data, lagging-end telomeres of cells lacking CST-Polα-primase lost 50-60 nt of telomeric CCCTAA repeats per population doubling. The C-strands of leading-end telomeres shortened by around 100 nt per population doubling, reflecting the generation of 3' overhangs through resection. The measured overall C-strand shortening in the absence of CST-Polα-primase fill-in is consistent with the combined effects of incomplete lagging-strand synthesis and 5' resection at the leading ends. We conclude that canonical DNA replication creates two telomere end-replication problems that require telomerase to maintain the G-rich strand and CST-Polα-primase to maintain the C-strand.
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Affiliation(s)
- Hiroyuki Takai
- Laboratory for Cell Biology and Genetics, Rockefeller University, New York, NY, USA
| | - Valentina Aria
- Medical Research Council Laboratory of Molecular Biology, Cambridge, UK
| | - Pamela Borges
- Laboratory for Cell Biology and Genetics, Rockefeller University, New York, NY, USA
| | - Joseph T P Yeeles
- Medical Research Council Laboratory of Molecular Biology, Cambridge, UK.
| | - Titia de Lange
- Laboratory for Cell Biology and Genetics, Rockefeller University, New York, NY, USA.
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11
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Olson CL, Wuttke DS. Guardians of the Genome: How the Single-Stranded DNA-Binding Proteins RPA and CST Facilitate Telomere Replication. Biomolecules 2024; 14:263. [PMID: 38540683 PMCID: PMC10968030 DOI: 10.3390/biom14030263] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Revised: 02/02/2024] [Accepted: 02/20/2024] [Indexed: 04/26/2024] Open
Abstract
Telomeres act as the protective caps of eukaryotic linear chromosomes; thus, proper telomere maintenance is crucial for genome stability. Successful telomere replication is a cornerstone of telomere length regulation, but this process can be fraught due to the many intrinsic challenges telomeres pose to the replication machinery. In addition to the famous "end replication" problem due to the discontinuous nature of lagging strand synthesis, telomeres require various telomere-specific steps for maintaining the proper 3' overhang length. Bulk telomere replication also encounters its own difficulties as telomeres are prone to various forms of replication roadblocks. These roadblocks can result in an increase in replication stress that can cause replication forks to slow, stall, or become reversed. Ultimately, this leads to excess single-stranded DNA (ssDNA) that needs to be managed and protected for replication to continue and to prevent DNA damage and genome instability. RPA and CST are single-stranded DNA-binding protein complexes that play key roles in performing this task and help stabilize stalled forks for continued replication. The interplay between RPA and CST, their functions at telomeres during replication, and their specialized features for helping overcome replication stress at telomeres are the focus of this review.
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Affiliation(s)
- Conner L. Olson
- Department of Biochemistry, University of Colorado Boulder, Boulder, CO 80309, USA
| | - Deborah S. Wuttke
- Department of Biochemistry, University of Colorado Boulder, Boulder, CO 80309, USA
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12
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Kinzig CG, Zakusilo G, Takai KK, Myler LR, de Lange T. ATR blocks telomerase from converting DNA breaks into telomeres. Science 2024; 383:763-770. [PMID: 38359122 PMCID: PMC11267623 DOI: 10.1126/science.adg3224] [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: 12/15/2022] [Accepted: 12/13/2023] [Indexed: 02/17/2024]
Abstract
Telomerase, the enzyme that maintains telomeres at natural chromosome ends, should be repressed at double-strand breaks (DSBs), where neotelomere formation can cause terminal truncations. We developed an assay to detect neotelomere formation at Cas9- or I-SceI-induced DSBs in human cells. Telomerase added telomeric repeats to DSBs, leading to interstitial telomeric repeat insertions or the formation of functional neotelomeres accompanied by terminal deletions. The threat that telomerase poses to genome integrity was minimized by ataxia telangiectasia and Rad3-related (ATR) kinase signaling, which inhibited telomerase at resected DSBs. In addition to acting at resected DSBs, telomerase used the extruded strand in the Cas9 enzyme-product complex as a primer for neotelomere formation. We propose that although neotelomere formation is detrimental in normal human cells, it may allow cancer cells to escape from breakage-fusion-bridge cycles.
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Affiliation(s)
- Charles G. Kinzig
- Laboratory for Cell Biology and Genetics, The Rockefeller University, New York, NY 10065, USA
- Weill Cornell/Rockefeller/Sloan Kettering Tri-Institutional MD/PhD Program, New York, NY 10065, USA
| | - George Zakusilo
- Laboratory for Cell Biology and Genetics, The Rockefeller University, New York, NY 10065, USA
- Weill Cornell/Rockefeller/Sloan Kettering Tri-Institutional MD/PhD Program, New York, NY 10065, USA
| | - Kaori K. Takai
- Laboratory for Cell Biology and Genetics, The Rockefeller University, New York, NY 10065, USA
| | - Logan R. Myler
- Laboratory for Cell Biology and Genetics, The Rockefeller University, New York, NY 10065, USA
| | - Titia de Lange
- Laboratory for Cell Biology and Genetics, The Rockefeller University, New York, NY 10065, USA
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13
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Takai H, Aria V, Borges P, Yeeles JTP, de Lange T. CST-Polymeraseα-primase solves a second telomere end-replication problem. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.10.26.564248. [PMID: 37961611 PMCID: PMC10634868 DOI: 10.1101/2023.10.26.564248] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
Telomerase adds G-rich telomeric repeats to the 3' ends of telomeres1, counteracting telomere shortening caused by loss of telomeric 3' overhangs during leading-strand DNA synthesis ("the end-replication problem"2). We report a second end-replication problem that originates from the incomplete duplication of the C-rich telomeric repeat strand by lagging-strand synthesis. This problem is solved by CST-Polymeraseα(Polα)-primase fill-in synthesis. In vitro, priming for lagging-strand DNA replication does not occur on the 3' overhang and lagging-strand synthesis stops in an ~150-nt zone more than 26 nt from the end of the template. Consistent with the in vitro data, lagging-end telomeres of cells lacking CST-Polα-primase lost ~50-60 nt of CCCTAA repeats per population doubling (PD). The C-strands of leading-end telomeres shortened by ~100 nt/PD, reflecting the generation of 3' overhangs through resection. The measured overall C-strand shortening in absence of CST-Polα-primase fill-in is consistent with the combined effects of incomplete lagging-strand synthesis and 5' resection at the leading-ends. We conclude that canonical DNA replication creates two telomere end-replication problems that require telomerase to maintain the G-strand and CST-Polα-primase to maintain the C-strand.
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Affiliation(s)
- Hiroyuki Takai
- Laboratory for Cell Biology and Genetics, Rockefeller University, New York, USA
| | - Valentina Aria
- Medical Research Council Laboratory of Molecular Biology, Cambridge, CB2, 0QH
| | - Pamela Borges
- Laboratory for Cell Biology and Genetics, Rockefeller University, New York, USA
| | - Joseph T. P. Yeeles
- Medical Research Council Laboratory of Molecular Biology, Cambridge, CB2, 0QH
| | - Titia de Lange
- Laboratory for Cell Biology and Genetics, Rockefeller University, New York, USA
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14
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Lim CJ. Telomere C-Strand Fill-In Machinery: New Insights into the Human CST-DNA Polymerase Alpha-Primase Structures and Functions. Subcell Biochem 2024; 104:73-100. [PMID: 38963484 DOI: 10.1007/978-3-031-58843-3_5] [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] [Indexed: 07/05/2024]
Abstract
Telomeres at the end of eukaryotic chromosomes are extended by a specialized set of enzymes and telomere-associated proteins, collectively termed here the telomere "replisome." The telomere replisome acts on a unique replicon at each chromosomal end of the telomeres, the 3' DNA overhang. This telomere replication process is distinct from the replisome mechanism deployed to duplicate the human genome. The G-rich overhang is first extended before the complementary C-strand is filled in. This overhang is extended by telomerase, a specialized ribonucleoprotein and reverse transcriptase. The overhang extension process is terminated when telomerase is displaced by CTC1-STN1-TEN1 (CST), a single-stranded DNA-binding protein complex. CST then recruits DNA polymerase α-primase to complete the telomere replication process by filling in the complementary C-strand. In this chapter, the recent structure-function insights into the human telomere C-strand fill-in machinery (DNA polymerase α-primase and CST) will be discussed.
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Affiliation(s)
- Ci Ji Lim
- Department of Biochemistry, College of Agricultural and Life Sciences, University of Wisconsin-Madison, Madison, WI, USA.
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15
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Carvalho Borges PC, Bouabboune C, Escandell JM, Matmati S, Coulon S, Ferreira MG. Pot1 promotes telomere DNA replication via the Stn1-Ten1 complex in fission yeast. Nucleic Acids Res 2023; 51:12325-12336. [PMID: 37953281 PMCID: PMC10711446 DOI: 10.1093/nar/gkad1036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Revised: 10/19/2023] [Accepted: 10/31/2023] [Indexed: 11/14/2023] Open
Abstract
Telomeres are nucleoprotein complexes that protect the chromosome-ends from eliciting DNA repair while ensuring their complete duplication. Pot1 is a subunit of telomere capping complex that binds to the G-rich overhang and inhibits the activation of DNA damage checkpoints. In this study, we explore new functions of fission yeast Pot1 by using a pot1-1 temperature sensitive mutant. We show that pot1 inactivation impairs telomere DNA replication resulting in the accumulation of ssDNA leading to the complete loss of telomeric DNA. Recruitment of Stn1 to telomeres, an auxiliary factor of DNA lagging strand synthesis, is reduced in pot1-1 mutants and overexpression of Stn1 rescues loss of telomeres and cell viability at restrictive temperature. We propose that Pot1 plays a crucial function in telomere DNA replication by recruiting Stn1-Ten1 and Polα-primase complex to telomeres via Tpz1, thus promoting lagging-strand DNA synthesis at stalled replication forks.
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Affiliation(s)
| | - Chaïnez Bouabboune
- CNRS, INSERM, Aix Marseille Univ, Institut Paoli-Calmettes, CRCM, Equipe labellisée par la Ligue Nationale contre le Cancer, Marseille, F-13009, France
| | | | - Samah Matmati
- CNRS, INSERM, Aix Marseille Univ, Institut Paoli-Calmettes, CRCM, Equipe labellisée par la Ligue Nationale contre le Cancer, Marseille, F-13009, France
| | - Stéphane Coulon
- CNRS, INSERM, Aix Marseille Univ, Institut Paoli-Calmettes, CRCM, Equipe labellisée par la Ligue Nationale contre le Cancer, Marseille, F-13009, France
| | - Miguel Godinho Ferreira
- Instituto Gulbenkian de Ciência, Oeiras, 2781-901, Portugal
- Institute for Research on Cancer and Aging of Nice (IRCAN), INSERM U1081 UMR7284 CNRS, 06107 Nice, France
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16
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Le Clercq LS, Kotzé A, Grobler JP, Dalton DL. Biological clocks as age estimation markers in animals: a systematic review and meta-analysis. Biol Rev Camb Philos Soc 2023; 98:1972-2011. [PMID: 37356823 DOI: 10.1111/brv.12992] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Revised: 06/04/2023] [Accepted: 06/08/2023] [Indexed: 06/27/2023]
Abstract
Various biological attributes associated with individual fitness in animals change predictably over the lifespan of an organism. Therefore, the study of animal ecology and the work of conservationists frequently relies upon the ability to assign animals to functionally relevant age classes to model population fitness. Several approaches have been applied to determining individual age and, while these methods have proved useful, they are not without limitations and often lack standardisation or are only applicable to specific species. For these reasons, scientists have explored the potential use of biological clocks towards creating a universal age-determination method. Two biological clocks, tooth layer annulation and otolith layering have found universal appeal. Both methods are highly invasive and most appropriate for post-mortem age-at-death estimation. More recently, attributes of cellular ageing previously explored in humans have been adapted to studying ageing in animals for the use of less-invasive molecular methods for determining age. Here, we review two such methods, assessment of methylation and telomere length, describing (i) what they are, (ii) how they change with age, and providing (iii) a summary and meta-analysis of studies that have explored their utility in animal age determination. We found that both attributes have been studied across multiple vertebrate classes, however, telomere studies were used before methylation studies and telomere length has been modelled in nearly twice as many studies. Telomere length studies included in the review often related changes to stress responses and illustrated that telomere length is sensitive to environmental and social stressors and, in the absence of repair mechanisms such as telomerase or alternative lengthening modes, lacks the ability to recover. Methylation studies, however, while also detecting sensitivity to stressors and toxins, illustrated the ability to recover from such stresses after a period of accelerated ageing, likely due to constitutive expression or reactivation of repair enzymes such as DNA methyl transferases. We also found that both studied attributes have parentally heritable features, but the mode of inheritance differs among taxa and may relate to heterogamy. Our meta-analysis included more than 40 species in common for methylation and telomere length, although both analyses included at least 60 age-estimation models. We found that methylation outperforms telomere length in terms of predictive power evidenced from effect sizes (more than double that observed for telomeres) and smaller prediction intervals. Both methods produced age correlation models using similar sample sizes and were able to classify individuals into young, middle, or old age classes with high accuracy. Our review and meta-analysis illustrate that both methods are well suited to studying age in animals and do not suffer significantly from variation due to differences in the lifespan of the species, genome size, karyotype, or tissue type but rather that quantitative method, patterns of inheritance, and environmental factors should be the main considerations. Thus, provided that complex factors affecting the measured trait can be accounted for, both methylation and telomere length are promising targets to develop as biomarkers for age determination in animals.
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Affiliation(s)
- Louis-Stéphane Le Clercq
- South African National Biodiversity Institute, P.O. Box 754, Pretoria, 0001, South Africa
- Department of Genetics, University of the Free State, P.O. Box 339, Bloemfontein, 9300, South Africa
| | - Antoinette Kotzé
- South African National Biodiversity Institute, P.O. Box 754, Pretoria, 0001, South Africa
- Department of Genetics, University of the Free State, P.O. Box 339, Bloemfontein, 9300, South Africa
| | - J Paul Grobler
- Department of Genetics, University of the Free State, P.O. Box 339, Bloemfontein, 9300, South Africa
| | - Desiré Lee Dalton
- School of Health and Life Sciences, Teesside University, Middlesbrough, TS1 3BA, UK
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17
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Li B. Telomere maintenance in African trypanosomes. Front Mol Biosci 2023; 10:1302557. [PMID: 38074093 PMCID: PMC10704157 DOI: 10.3389/fmolb.2023.1302557] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Accepted: 11/15/2023] [Indexed: 02/12/2024] Open
Abstract
Telomere maintenance is essential for genome integrity and chromosome stability in eukaryotic cells harboring linear chromosomes, as telomere forms a specialized structure to mask the natural chromosome ends from DNA damage repair machineries and to prevent nucleolytic degradation of the telomeric DNA. In Trypanosoma brucei and several other microbial pathogens, virulence genes involved in antigenic variation, a key pathogenesis mechanism essential for host immune evasion and long-term infections, are located at subtelomeres, and expression and switching of these major surface antigens are regulated by telomere proteins and the telomere structure. Therefore, understanding telomere maintenance mechanisms and how these pathogens achieve a balance between stability and plasticity at telomere/subtelomere will help develop better means to eradicate human diseases caused by these pathogens. Telomere replication faces several challenges, and the "end replication problem" is a key obstacle that can cause progressive telomere shortening in proliferating cells. To overcome this challenge, most eukaryotes use telomerase to extend the G-rich telomere strand. In addition, a number of telomere proteins use sophisticated mechanisms to coordinate the telomerase-mediated de novo telomere G-strand synthesis and the telomere C-strand fill-in, which has been extensively studied in mammalian cells. However, we recently discovered that trypanosomes lack many telomere proteins identified in its mammalian host that are critical for telomere end processing. Rather, T. brucei uses a unique DNA polymerase, PolIE that belongs to the DNA polymerase A family (E. coli DNA PolI family), to coordinate the telomere G- and C-strand syntheses. In this review, I will first briefly summarize current understanding of telomere end processing in mammals. Subsequently, I will describe PolIE-mediated coordination of telomere G- and C-strand synthesis in T. brucei and implication of this recent discovery.
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Affiliation(s)
- Bibo Li
- Center for Gene Regulation in Health and Disease, Department of Biological, Geological, and Environmental Sciences, College of Arts and Sciences, Cleveland State University, Cleveland, OH, United States
- Case Comprehensive Cancer Center, Case Western Reserve University, Cleveland, OH, United States
- Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, United States
- Center for RNA Science and Therapeutics, Case Western Reserve University, Cleveland, OH, United States
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18
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Gold NM, Okeke MN, He Y. Involvement of Inheritance in Determining Telomere Length beyond Environmental and Lifestyle Factors. Aging Dis 2023; 15:2470-2490. [PMID: 37962459 PMCID: PMC11567259 DOI: 10.14336/ad.2023.1023] [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: 08/20/2023] [Accepted: 10/23/2023] [Indexed: 11/15/2023] Open
Abstract
All linear chromosomal ends have specific DNA-protein complexes called telomeres. Telomeres serve as a "molecular clock" to estimate the potential length of cell replication. Shortening of telomere length (TL) is associated with cellular senescence, aging, and various age-related diseases in humans. Here we reviewed the structure, function, and regulation of telomeres and the age-related diseases associated with telomere attrition. Among the various determinants of TL, we highlight the connection between TL and heredity to provide a new overview of genetic determinants for TL. Studies across multiple species have shown that maternal and paternal TL influence the TL of their offspring, and this may affect life span and their susceptibility to age-related diseases. Hence, we reviewed the linkage between TL and parental influences and the proposed mechanisms involved. More in-depth studies on the genetic mechanism for TL attrition are needed due to the potential application of this knowledge in human medicine to prevent premature frailty at its earliest stage, as well as promote health and longevity.
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Affiliation(s)
- Naheemat Modupeola Gold
- Key Laboratory of Healthy Aging Research of Yunnan Province, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming 650201, Yunnan, China.
- State Key Laboratory of Genetic, Evolution and Animal Models, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming 650201, Yunnan, China.
- University of Chinese Academy of Sciences, Beijing 100049, China.
| | - Michael Ngozi Okeke
- University of Chinese Academy of Sciences, Beijing 100049, China.
- Center for Nanomedical Technology Research, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China.
| | - Yonghan He
- Key Laboratory of Healthy Aging Research of Yunnan Province, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming 650201, Yunnan, China.
- State Key Laboratory of Genetic, Evolution and Animal Models, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming 650201, Yunnan, China.
- University of Chinese Academy of Sciences, Beijing 100049, China.
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19
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Sze S, Bhardwaj A, Fnu P, Azarm K, Mund R, Ring K, Smith S. TERRA R-loops connect and protect sister telomeres in mitosis. Cell Rep 2023; 42:113235. [PMID: 37843976 PMCID: PMC10873023 DOI: 10.1016/j.celrep.2023.113235] [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: 04/27/2023] [Revised: 08/08/2023] [Accepted: 09/22/2023] [Indexed: 10/18/2023] Open
Abstract
Resolution of cohesion between sister telomeres in human cells depends on TRF1-mediated recruitment of the polyADP-ribosyltransferase tankyrase to telomeres. In human aged cells, due to insufficient recruitment of TRF1/tankyrase to shortened telomeres, sisters remain cohered in mitosis. This persistent cohesion plays a protective role, but the mechanism by which sisters remain cohered is not well understood. Here we show that telomere repeat-containing RNA (TERRA) holds sister telomeres together through RNA-DNA hybrid (R-loop) structures. We show that a tankyrase-interacting partner, the RNA-binding protein C19orf43, is required for repression of TERRA R-loops. Persistent telomere cohesion in C19orf43-depleted cells is counteracted by RNaseH1, confirming that RNA-DNA hybrids hold sisters together. Consistent with a protective role for persistent telomere cohesion, depletion of C19orf43 in aged cells reduces DNA damage and delays replicative senescence. We propose that the inherent inability of shortened telomeres to recruit R-loop-repressing machinery permits a controlled onset of senescence.
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Affiliation(s)
- Samantha Sze
- Department of Cell Biology, New York University School of Medicine, New York, NY 10016, USA
| | | | - Priyanka Fnu
- University of Rochester Medical Center, Rochester, NY 14642, USA
| | | | - Rachel Mund
- New York Medical College, Valhalla, NY 10595, USA
| | - Katherine Ring
- Department of Cell Biology, New York University School of Medicine, New York, NY 10016, USA
| | - Susan Smith
- Department of Cell Biology, New York University School of Medicine, New York, NY 10016, USA.
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20
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El-Khoury R, Roman M, Assi HA, Moye AL, Bryan T, Damha M. Telomeric i-motifs and C-strands inhibit parallel G-quadruplex extension by telomerase. Nucleic Acids Res 2023; 51:10395-10410. [PMID: 37742080 PMCID: PMC10602923 DOI: 10.1093/nar/gkad764] [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: 05/29/2023] [Revised: 08/23/2023] [Accepted: 09/11/2023] [Indexed: 09/25/2023] Open
Abstract
Telomeric C-rich repeated DNA sequences fold into tetrahelical i-motif structures in vitro at acidic pH. While studies have suggested that i-motifs may form in cells, little is known about their potential role in human telomere biology. In this study, we explore the effect of telomeric C-strands and i-motifs on the ability of human telomerase to extend G-rich substrates. To promote i-motif formation at neutral pH, we use telomeric sequences where the cytidines have been substituted with 2'-fluoroarabinocytidine. Using FRET-based studies, we show that the stabilized i-motifs resist hybridization to concomitant parallel G-quadruplexes, implying that both structures could exist simultaneously at telomeric termini. Moreover, through telomerase activity assays, we show that both unstructured telomeric C-strands and telomeric i-motifs can inhibit the activity and processivity of telomerase extension of parallel G-quadruplexes and linear telomeric DNA. The data suggest at least three modes of inhibition by C-strands and i-motifs: direct hybridization to the substrate DNA, hybridization to nascent product DNA resulting in early telomerase dissociation, and interference with the unique mechanism of telomerase unwinding and extension of a G-quadruplex. Overall, this study highlights a potential inhibitory role for the telomeric C-strand in telomere maintenance.
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Affiliation(s)
- Roberto El-Khoury
- Department of Chemistry, McGill University, Montreal, Quebec H3A 0B8, Canada
| | - Morgane Roman
- Department of Chemistry, McGill University, Montreal, Quebec H3A 0B8, Canada
| | - Hala Abou Assi
- Department of Chemistry, McGill University, Montreal, Quebec H3A 0B8, Canada
| | - Aaron L Moye
- Children's Medical Research Institute, Faculty of Medicine and Health, University of Sydney, Westmead, NSW 2145, Australia
| | - Tracy M Bryan
- Children's Medical Research Institute, Faculty of Medicine and Health, University of Sydney, Westmead, NSW 2145, Australia
| | - Masad J Damha
- Department of Chemistry, McGill University, Montreal, Quebec H3A 0B8, Canada
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21
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Cai SW, Takai H, Walz T, de Lange T. POT1 recruits and regulates CST-Polα/Primase at human telomeres. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.08.539880. [PMID: 37215005 PMCID: PMC10197580 DOI: 10.1101/2023.05.08.539880] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Telomere maintenance requires extension of the G-rich telomeric repeat strand by telomerase and fill-in synthesis of the C-rich strand by Polα/Primase. Telomeric Polα/Primase is bound to Ctc1-Stn1-Ten1 (CST), a single-stranded DNA-binding complex. Like mutations in telomerase, mutations affecting CST-Polα/Primase result in pathological telomere shortening and cause a telomere biology disorder, Coats plus (CP). We determined cryogenic electron microscopy structures of human CST bound to the shelterin heterodimer POT1/TPP1 that reveal how CST is recruited to telomeres by POT1. Phosphorylation of POT1 is required for CST recruitment, and the complex is formed through conserved interactions involving several residues mutated in CP. Our structural and biochemical data suggest that phosphorylated POT1 holds CST-Polα/Primase in an inactive auto-inhibited state until telomerase has extended the telomere ends. We propose that dephosphorylation of POT1 releases CST-Polα/Primase into an active state that completes telomere replication through fill-in synthesis.
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Affiliation(s)
- Sarah W. Cai
- Laboratory of Cell Biology and Genetics, The Rockefeller University; New York, NY, USA
- Laboratory of Molecular Electron Microscopy, The Rockefeller University; New York, NY, USA
| | - Hiroyuki Takai
- Laboratory of Cell Biology and Genetics, The Rockefeller University; New York, NY, USA
| | - Thomas Walz
- Laboratory of Molecular Electron Microscopy, The Rockefeller University; New York, NY, USA
| | - Titia de Lange
- Laboratory of Cell Biology and Genetics, The Rockefeller University; New York, NY, USA
- Lead contact
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22
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He Q, Lim CJ. Models for human telomere C-strand fill-in by CST-Polα-primase. Trends Biochem Sci 2023; 48:860-872. [PMID: 37586999 PMCID: PMC10528720 DOI: 10.1016/j.tibs.2023.07.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2023] [Revised: 07/12/2023] [Accepted: 07/18/2023] [Indexed: 08/18/2023]
Abstract
Telomere maintenance is essential for the genome integrity of eukaryotes, and this function is underpinned by the two-step telomeric DNA synthesis process: telomere G-overhang extension by telomerase and complementary strand fill-in by DNA polymerase alpha-primase (polα-primase). Compared to the telomerase step, the telomere C-strand fill-in mechanism is less understood. Recent studies have provided new insights into how telomeric single-stranded DNA-binding protein CTC1-STN1-TEN1 (CST) and polα-primase coordinate to synthesize the telomeric C-strand for telomere overhang fill-in. Cryogenic electron microscopy (cryo-EM) structures of CST-polα-primase complexes have provided additional insights into how they assemble at telomeric templates and de novo synthesize the telomere C-strand. In this review, we discuss how these latest findings coalesce with existing understanding to develop a human telomere C-strand fill-in mechanism model.
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Affiliation(s)
- Qixiang He
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, USA
| | - Ci Ji Lim
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, USA.
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23
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Takasugi T, Gu P, Liang F, Staco I, Chang S. Pot1b -/- tumors activate G-quadruplex-induced DNA damage to promote telomere hyper-elongation. Nucleic Acids Res 2023; 51:9227-9247. [PMID: 37560909 PMCID: PMC10516629 DOI: 10.1093/nar/gkad648] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Revised: 07/14/2023] [Accepted: 07/22/2023] [Indexed: 08/11/2023] Open
Abstract
Malignant cancers must activate telomere maintenance mechanisms to achieve replicative immortality. Mutations in the human Protection of Telomeres 1 (POT1) gene are frequently detected in cancers with abnormally long telomeres, suggesting that the loss of POT1 function disrupts the regulation of telomere length homeostasis to promote telomere elongation. However, our understanding of the mechanisms leading to elongated telomeres remains incomplete. The mouse genome encodes two POT1 proteins, POT1a and POT1b possessing separation of hPOT1 functions. We performed serial transplantation of Pot1b-/- sarcomas to better understand the role of POT1b in regulating telomere length maintenance. While early-generation Pot1b-/- sarcomas initially possessed shortened telomeres, late-generation Pot1b-/- cells display markedly hyper-elongated telomeres that were recognized as damaged DNA by the Replication Protein A (RPA) complex. The RPA-ATR-dependent DNA damage response at telomeres promotes telomerase recruitment to facilitate telomere hyper-elongation. POT1b, but not POT1a, was able to unfold G-quadruplex present in hyper-elongated telomeres to repress the DNA damage response. Our findings demonstrate that the repression of the RPA-ATR DDR is conserved between POT1b and human POT1, suggesting that similar mechanisms may underly the phenotypes observed in human cancers harboring human POT1 mutations.
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Affiliation(s)
- Taylor Takasugi
- Department of Laboratory Medicine, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Peili Gu
- Department of Laboratory Medicine, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Fengshan Liang
- Department of Laboratory Medicine, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Isabelle Staco
- Department of Laboratory Medicine, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Sandy Chang
- Department of Laboratory Medicine, Yale University School of Medicine, New Haven, CT 06520, USA
- Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, CT 06520, USA
- Department of Pathology, Yale University School of Medicine, New Haven, CT 06520, USA
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24
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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: 8] [Impact Index Per Article: 8.0] [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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25
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Roisné-Hamelin F, Marcand S. All roads lead to MRN regulation at telomeres: different paths to one solution. Nat Struct Mol Biol 2023; 30:1242-1243. [PMID: 37653240 DOI: 10.1038/s41594-023-01077-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/02/2023]
Affiliation(s)
- Florian Roisné-Hamelin
- Department of Fundamental Microbiology (DMF), Faculty of Biology and Medicine (FBM), University of Lausanne (UNIL), Lausanne, Switzerland
| | - Stéphane Marcand
- Université Paris-Saclay, Université Paris-Cité, Inserm, CEA, Institut de Biologie François Jacob, iRCM, UMR Stabilité Génétique Cellules Souches et Radiations, Fontenay-aux-Roses, France.
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26
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Tesmer VM, Brenner KA, Nandakumar J. Human POT1 protects the telomeric ds-ss DNA junction by capping the 5' end of the chromosome. Science 2023; 381:771-778. [PMID: 37590346 PMCID: PMC10666826 DOI: 10.1126/science.adi2436] [Citation(s) in RCA: 14] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Accepted: 07/19/2023] [Indexed: 08/19/2023]
Abstract
Protection of telomeres 1 (POT1) is the 3' single-stranded overhang-binding telomeric protein that prevents an ataxia telangiectasia and Rad3-related (ATR) DNA damage response (DDR) at chromosome ends. What precludes the DDR machinery from accessing the telomeric double-stranded-single-stranded junction is unknown. We demonstrate that human POT1 binds this junction by recognizing the phosphorylated 5' end of the chromosome. High-resolution crystallographic structures reveal that the junction is capped by POT1 through a "POT-hole" surface, the mutation of which compromises junction protection in vitro and telomeric 5'-end definition and DDR suppression in human cells. Whereas both mouse POT1 paralogs bind the single-stranded overhang, POT1a, not POT1b, contains a POT-hole and binds the junction, which explains POT1a's sufficiency for end protection. Our study shifts the paradigm for DDR suppression at telomeres by highlighting the importance of protecting the double-stranded-single-stranded junction.
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Affiliation(s)
- Valerie M. Tesmer
- Department of Molecular, Cellular and Developmental Biology, University of Michigan; Ann Arbor, 48109, USA
| | - Kirsten A. Brenner
- Department of Molecular, Cellular and Developmental Biology, University of Michigan; Ann Arbor, 48109, USA
| | - Jayakrishnan Nandakumar
- Department of Molecular, Cellular and Developmental Biology, University of Michigan; Ann Arbor, 48109, USA
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27
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Abstract
It has been known for decades that telomerase extends the 3' end of linear eukaryotic chromosomes and dictates the telomeric repeat sequence based on the template in its RNA. However, telomerase does not mitigate sequence loss at the 5' ends of chromosomes, which results from lagging strand DNA synthesis and nucleolytic processing. Therefore, a second enzyme is needed to keep telomeres intact: DNA polymerase α/Primase bound to Ctc1-Stn1-Ten1 (CST). CST-Polα/Primase maintains telomeres through a fill-in reaction that replenishes the lost sequences at the 5' ends. CST not only serves to maintain telomeres but also determines their length by keeping telomerase from overelongating telomeres. Here we discuss recent data on the evolution, structure, function, and recruitment of mammalian CST-Polα/Primase, highlighting the role of this complex and telomere length control in human disease.
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Affiliation(s)
- Sarah W Cai
- Laboratory for Cell Biology and Genetics, The Rockefeller University, New York, New York 10065, USA
| | - Titia de Lange
- Laboratory for Cell Biology and Genetics, The Rockefeller University, New York, New York 10065, USA
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28
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Zade NH, Khattar E. POT1 mutations cause differential effects on telomere length leading to opposing disease phenotypes. J Cell Physiol 2023; 238:1237-1255. [PMID: 37183325 DOI: 10.1002/jcp.31034] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2023] [Revised: 03/28/2023] [Accepted: 04/17/2023] [Indexed: 05/16/2023]
Abstract
The protection of telomere protein (POT1) is a telomere-binding protein and is an essential component of the six-membered shelterin complex, which is associated with the telomeres. POT1 directly binds to the 3' single-stranded telomeric overhang and prevents the activation of DNA damage response at telomeres thus preventing the telomere-telomere fusions and genomic instability. POT1 also plays a pivotal role in maintaining telomere length by regulating telomerase-mediated telomere elongation. Mutations in POT1 proteins result in three different telomere phenotypes, which include long, short, or aberrant telomere length. Long telomeres predispose individuals to cancer, while short or aberrant telomere phenotypes result in pro-aging diseases referred to as telomeropathies. Here, we review the function of POT1 proteins in telomere length hemostasis and how the spectrum of mutations reported in POT1 can be segregated toward developing very distinct disease phenotypes of cancer and telomeropathies.
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Affiliation(s)
- Nikita Harish Zade
- Sunandan Divatia School of Science, SVKM's NMIMS (Deemed to be) University, Mumbai, India
| | - Ekta Khattar
- Sunandan Divatia School of Science, SVKM's NMIMS (Deemed to be) University, Mumbai, India
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29
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Moreno SP, Fusté JM, Kaiser M, Li JSZ, Nassour J, Haggblom C, Denchi EL, Karlseder J. TZAP overexpression induces telomere dysfunction and ALT-like activity in ATRX/DAXX-deficient cells. iScience 2023; 26:106405. [PMID: 37013192 PMCID: PMC10066556 DOI: 10.1016/j.isci.2023.106405] [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: 10/15/2022] [Revised: 11/13/2022] [Accepted: 03/10/2023] [Indexed: 03/14/2023] Open
Abstract
The appropriate regulation of telomere length homeostasis is crucial for the maintenance of genome integrity. The telomere-binding protein TZAP has been suggested to regulate telomere length by promoting t-circle and c-circle excisions through telomere trimming, yet the molecular mechanisms by which TZAP functions at telomeres are not understood. Using a system based on TZAP overexpression, we show that efficient TZAP recruitment to telomeres occurs in the context of open telomeric chromatin caused by loss of ATRX/DAXX independently of H3.3 deposition. Moreover, our data indicate that TZAP binding to telomeres induces telomere dysfunction and ALT-like activity, resulting in the generation of t-circles and c-circles in a Bloom-Topoisomerase IIIα-RMI1-RMI2 (BTR)-dependent manner.
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Affiliation(s)
- Sara Priego Moreno
- The Salk Institute for Biological Studies, Molecular and Cell Biology Department, 10010 N. Torrey pines Road, La Jolla, CA 92037, USA
| | - Javier Miralles Fusté
- The Salk Institute for Biological Studies, Molecular and Cell Biology Department, 10010 N. Torrey pines Road, La Jolla, CA 92037, USA
| | - Melanie Kaiser
- The Salk Institute for Biological Studies, Molecular and Cell Biology Department, 10010 N. Torrey pines Road, La Jolla, CA 92037, USA
| | - Julia Su Zhou Li
- The Ludwig Institute for Cancer Research, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Joe Nassour
- The Salk Institute for Biological Studies, Molecular and Cell Biology Department, 10010 N. Torrey pines Road, La Jolla, CA 92037, USA
| | - Candy Haggblom
- The Salk Institute for Biological Studies, Molecular and Cell Biology Department, 10010 N. Torrey pines Road, La Jolla, CA 92037, USA
| | - Eros Lazzerini Denchi
- Laboratory for Genome Integrity, National Cancer Institute, Building 37, Room 2144B, Bethesda, MD 20892, USA
| | - Jan Karlseder
- The Salk Institute for Biological Studies, Molecular and Cell Biology Department, 10010 N. Torrey pines Road, La Jolla, CA 92037, USA
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30
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Pennarun G, Picotto J, Bertrand P. Close Ties between the Nuclear Envelope and Mammalian Telomeres: Give Me Shelter. Genes (Basel) 2023; 14:genes14040775. [PMID: 37107534 PMCID: PMC10137478 DOI: 10.3390/genes14040775] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Revised: 03/18/2023] [Accepted: 03/20/2023] [Indexed: 04/29/2023] Open
Abstract
The nuclear envelope (NE) in eukaryotic cells is essential to provide a protective compartment for the genome. Beside its role in connecting the nucleus with the cytoplasm, the NE has numerous important functions including chromatin organization, DNA replication and repair. NE alterations have been linked to different human diseases, such as laminopathies, and are a hallmark of cancer cells. Telomeres, the ends of eukaryotic chromosomes, are crucial for preserving genome stability. Their maintenance involves specific telomeric proteins, repair proteins and several additional factors, including NE proteins. Links between telomere maintenance and the NE have been well established in yeast, in which telomere tethering to the NE is critical for their preservation and beyond. For a long time, in mammalian cells, except during meiosis, telomeres were thought to be randomly localized throughout the nucleus, but recent advances have uncovered close ties between mammalian telomeres and the NE that play important roles for maintaining genome integrity. In this review, we will summarize these connections, with a special focus on telomere dynamics and the nuclear lamina, one of the main NE components, and discuss the evolutionary conservation of these mechanisms.
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Affiliation(s)
- Gaëlle Pennarun
- Université Paris Cité, INSERM, CEA, Stabilité Génétique Cellules Souches et Radiations, LREV/iRCM/IBFJ, F-92260 Fontenay-aux-Roses, France
- Université Paris-Saclay, INSERM, CEA, Stabilité Génétique Cellules Souches et Radiations, LREV/iRCM/IBFJ, F-92260 Fontenay-aux-Roses, France
| | - Julien Picotto
- Université Paris Cité, INSERM, CEA, Stabilité Génétique Cellules Souches et Radiations, LREV/iRCM/IBFJ, F-92260 Fontenay-aux-Roses, France
- Université Paris-Saclay, INSERM, CEA, Stabilité Génétique Cellules Souches et Radiations, LREV/iRCM/IBFJ, F-92260 Fontenay-aux-Roses, France
| | - Pascale Bertrand
- Université Paris Cité, INSERM, CEA, Stabilité Génétique Cellules Souches et Radiations, LREV/iRCM/IBFJ, F-92260 Fontenay-aux-Roses, France
- Université Paris-Saclay, INSERM, CEA, Stabilité Génétique Cellules Souches et Radiations, LREV/iRCM/IBFJ, F-92260 Fontenay-aux-Roses, France
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31
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Nelson N, Feurstein S, Niaz A, Truong J, Holien JK, Lucas S, Fairfax K, Dickinson J, Bryan TM. Functional genomics for curation of variants in telomere biology disorder associated genes: A systematic review. Genet Med 2023; 25:100354. [PMID: 36496180 DOI: 10.1016/j.gim.2022.11.021] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Revised: 11/28/2022] [Accepted: 11/30/2022] [Indexed: 12/12/2022] Open
Abstract
PURPOSE Patients with an underlying telomere biology disorder (TBD) have variable clinical presentations, and they can be challenging to diagnose clinically. A genomic diagnosis for patients presenting with TBD is vital for optimal treatment. Unfortunately, many variants identified during diagnostic testing are variants of uncertain significance. This complicates management decisions, delays treatment, and risks nonuptake of potentially curative therapies. Improved application of functional genomic evidence may reduce variants of uncertain significance classifications. METHODS We systematically searched the literature for published functional assays interrogating TBD gene variants. When possible, established likely benign/benign and likely pathogenic/pathogenic variants were used to estimate the assay sensitivity, specificity, positive predictive value, negative predictive value, and odds of pathogenicity. RESULTS In total, 3131 articles were screened and 151 met inclusion criteria. Sufficient data to enable a PS3/BS3 recommendation were available for TERT variants only. We recommend that PS3 and BS3 can be applied at a moderate and supportive level, respectively. PS3/BS3 application was limited by a lack of assay standardization and limited inclusion of benign variants. CONCLUSION Further assay standardization and assessment of benign variants are required for optimal use of the PS3/BS3 criterion for TBD gene variant classification.
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Affiliation(s)
- Niles Nelson
- The Menzies Institute for Medical Research, College of Health and Medicine, The University of Tasmania, Hobart, Tasmania, Australia; Department of Molecular Medicine, The Royal Hobart Hospital, Hobart, Tasmania, Australia; Department of Molecular Haematology, The Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia.
| | - Simone Feurstein
- Section of Hematology, Oncology, and Rheumatology, Department of Internal Medicine, Heidelberg University Hospital, Heidelberg, Germany
| | - Aram Niaz
- Children's Medical Research Institute, Faculty of Medicine and Health, University of Sydney, Westmead, New South Wales, Australia
| | - Jia Truong
- School of Science, STEM College, RMIT University, Bundoora, Victoria, Australia
| | - Jessica K Holien
- School of Science, STEM College, RMIT University, Bundoora, Victoria, Australia
| | - Sionne Lucas
- The Menzies Institute for Medical Research, College of Health and Medicine, The University of Tasmania, Hobart, Tasmania, Australia
| | - Kirsten Fairfax
- The Menzies Institute for Medical Research, College of Health and Medicine, The University of Tasmania, Hobart, Tasmania, Australia
| | - Joanne Dickinson
- The Menzies Institute for Medical Research, College of Health and Medicine, The University of Tasmania, Hobart, Tasmania, Australia
| | - Tracy M Bryan
- Children's Medical Research Institute, Faculty of Medicine and Health, University of Sydney, Westmead, New South Wales, Australia
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32
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Mirman Z, Cai S, de Lange T. CST/Polα/primase-mediated fill-in synthesis at DSBs. Cell Cycle 2023; 22:379-389. [PMID: 36205622 PMCID: PMC9879193 DOI: 10.1080/15384101.2022.2123886] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Revised: 08/27/2022] [Accepted: 09/06/2022] [Indexed: 01/29/2023] Open
Abstract
DNA double-strand breaks (DSBs) pose a major threat to the genome, so the efficient repair of such breaks is essential. DSB processing and repair is affected by 53BP1, which has been proposed to determine repair pathway choice and/or promote repair fidelity. 53BP1 and its downstream effectors, RIF1 and shieldin, control 3' overhang length, and the mechanism has been a topic of intensive research. Here, we highlight recent evidence that 3' overhang control by 53BP1 occurs through fill-in synthesis of resected DSBs by CST/Polα/primase. We focus on the crucial role of fill-in synthesis in BRCA1-deficient cells treated with PARPi and discuss the notion of fill-in synthesis in other specialized settings and in the repair of random DSBs. We argue that - in addition to other determinants - repair pathway choice may be influenced by the DNA sequence at the break which can impact CST binding and therefore the deployment of Polα/primase fill-in.
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Affiliation(s)
- Zachary Mirman
- Laboratory for Cell Biology and Genetics, The Rockefeller University, New York, NY, USA
- Department of Genetics, Harvard Medical School, Division of Genetics, Brigham and Women’s Hospital, HHMI, Boston, MA, USA
| | - Sarah Cai
- Laboratory for Cell Biology and Genetics, The Rockefeller University, New York, NY, USA
- Laboratory for Molecular Electron Microscopy, The Rockefeller University, New York, NY
| | - Titia de Lange
- Laboratory for Cell Biology and Genetics, The Rockefeller University, New York, NY, USA
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33
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Revy P, Kannengiesser C, Bertuch AA. Genetics of human telomere biology disorders. Nat Rev Genet 2023; 24:86-108. [PMID: 36151328 DOI: 10.1038/s41576-022-00527-z] [Citation(s) in RCA: 68] [Impact Index Per Article: 68.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/11/2022] [Indexed: 01/24/2023]
Abstract
Telomeres are specialized nucleoprotein structures at the ends of linear chromosomes that prevent the activation of DNA damage response and repair pathways. Numerous factors localize at telomeres to regulate their length, structure and function, to avert replicative senescence or genome instability and cell death. In humans, Mendelian defects in several of these factors can result in abnormally short or dysfunctional telomeres, causing a group of rare heterogeneous premature-ageing diseases, termed telomeropathies, short-telomere syndromes or telomere biology disorders (TBDs). Here, we review the TBD-causing genes identified so far and describe their main functions associated with telomere biology. We present molecular aspects of TBDs, including genetic anticipation, phenocopy, incomplete penetrance and somatic genetic rescue, which underlie the complexity of these diseases. We also discuss the implications of phenotypic and genetic features of TBDs on fundamental aspects related to human telomere biology, ageing and cancer, as well as on diagnostic, therapeutic and clinical approaches.
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Affiliation(s)
- Patrick Revy
- INSERM UMR 1163, Laboratory of Genome Dynamics in the Immune System, Equipe Labellisée Ligue Nationale contre le Cancer, Paris, France.
- Université Paris Cité, Imagine Institute, Paris, France.
| | - Caroline Kannengiesser
- APHP Service de Génétique, Hôpital Bichat, Paris, France
- Inserm U1152, Université Paris Cité, Paris, France
| | - Alison A Bertuch
- Departments of Paediatrics and Molecular & Human Genetics, Baylor College of Medicine, Houston, TX, USA
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34
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Schimmel J, van Wezel MD, van Schendel R, Tijsterman M. Chromosomal breaks at the origin of small tandem DNA duplications. Bioessays 2023; 45:e2200168. [PMID: 36385254 DOI: 10.1002/bies.202200168] [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: 08/26/2022] [Revised: 11/01/2022] [Accepted: 11/03/2022] [Indexed: 11/18/2022]
Abstract
Small tandem DNA duplications in the range of 15 to 300 base-pairs play an important role in the aetiology of human disease and contribute to genome diversity. Here, we discuss different proposed mechanisms for their occurrence and argue that this type of structural variation mainly results from mutagenic repair of chromosomal breaks. This hypothesis is supported by both bioinformatical analysis of insertions occurring in the genome of different species and disease alleles, as well as by CRISPR/Cas9-based experimental data from different model systems. Recent work points to fill-in synthesis at double-stranded DNA breaks with complementary sequences, regulated by end-joining mechanisms, to account for small tandem duplications. We will review the prevalence of small tandem duplications in the population, and we will speculate on the potential sources of DNA damage that could give rise to this mutational signature. With the development of novel algorithms to analyse sequencing data, small tandem duplications are now more frequently detected in the human genome and identified as oncogenic gain-of-function mutations. Understanding their origin could lead to optimized treatment regimens to prevent therapy-induced activation of oncogenes and might expose novel vulnerabilities in cancer.
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Affiliation(s)
- Joost Schimmel
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Marloes D van Wezel
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Robin van Schendel
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - Marcel Tijsterman
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
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35
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Cai Y, Song W, Li J, Jing Y, Liang C, Zhang L, Zhang X, Zhang W, Liu B, An Y, Li J, Tang B, Pei S, Wu X, Liu Y, Zhuang CL, Ying Y, Dou X, Chen Y, Xiao FH, Li D, Yang R, Zhao Y, Wang Y, Wang L, Li Y, Ma S, Wang S, Song X, Ren J, Zhang L, Wang J, Zhang W, Xie Z, Qu J, Wang J, Xiao Y, Tian Y, Wang G, Hu P, Ye J, Sun Y, Mao Z, Kong QP, Liu Q, Zou W, Tian XL, Xiao ZX, Liu Y, Liu JP, Song M, Han JDJ, Liu GH. The landscape of aging. SCIENCE CHINA. LIFE SCIENCES 2022; 65:2354-2454. [PMID: 36066811 PMCID: PMC9446657 DOI: 10.1007/s11427-022-2161-3] [Citation(s) in RCA: 131] [Impact Index Per Article: 65.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Accepted: 07/05/2022] [Indexed: 02/07/2023]
Abstract
Aging is characterized by a progressive deterioration of physiological integrity, leading to impaired functional ability and ultimately increased susceptibility to death. It is a major risk factor for chronic human diseases, including cardiovascular disease, diabetes, neurological degeneration, and cancer. Therefore, the growing emphasis on "healthy aging" raises a series of important questions in life and social sciences. In recent years, there has been unprecedented progress in aging research, particularly the discovery that the rate of aging is at least partly controlled by evolutionarily conserved genetic pathways and biological processes. In an attempt to bring full-fledged understanding to both the aging process and age-associated diseases, we review the descriptive, conceptual, and interventive aspects of the landscape of aging composed of a number of layers at the cellular, tissue, organ, organ system, and organismal levels.
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Affiliation(s)
- Yusheng Cai
- State Key Laboratory of Membrane Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China
- Institute for Stem Cell and Regeneration, Chinese Academy of Sciences, Beijing, 100101, China
- Beijing Institute for Stem Cell and Regenerative Medicine, Beijing, 100101, China
| | - Wei Song
- Frontier Science Center for Immunology and Metabolism, Medical Research Institute, College of Life Sciences, Wuhan University, Wuhan, 430071, China
| | - Jiaming Li
- CAS Key Laboratory of Genomic and Precision Medicine, Beijing Institute of Genomics, Chinese Academy of Sciences and China National Center for Bioinformation, Beijing, 100101, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Ying Jing
- University of Chinese Academy of Sciences, Beijing, 100049, China
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China
| | - Chuqian Liang
- State Key Laboratory of Membrane Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China
- Institute for Stem Cell and Regeneration, Chinese Academy of Sciences, Beijing, 100101, China
- Beijing Institute for Stem Cell and Regenerative Medicine, Beijing, 100101, China
| | - Liyuan Zhang
- CAS Key Laboratory of Genomic and Precision Medicine, Beijing Institute of Genomics, Chinese Academy of Sciences and China National Center for Bioinformation, Beijing, 100101, China
| | - Xia Zhang
- CAS Key Laboratory of Tissue Microenvironment and Tumor, Shanghai Institute of Nutrition and Health, Chinese Academy of Sciences, Shanghai, 200031, China
| | - Wenhui Zhang
- University of Chinese Academy of Sciences, Beijing, 100049, China
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, China
| | - Beibei Liu
- CAS Key Laboratory of Genomic and Precision Medicine, Beijing Institute of Genomics, Chinese Academy of Sciences and China National Center for Bioinformation, Beijing, 100101, China
| | - Yongpan An
- Peking University International Cancer Institute, Peking University Health Science Center, Peking University, Beijing, 100191, China
| | - Jingyi Li
- State Key Laboratory of Membrane Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China
- Institute for Stem Cell and Regeneration, Chinese Academy of Sciences, Beijing, 100101, China
- Beijing Institute for Stem Cell and Regenerative Medicine, Beijing, 100101, China
| | - Baixue Tang
- School of Pharmaceutical Sciences, Tsinghua University, Beijing, 100084, China
| | - Siyu Pei
- CAS Key Laboratory of Tissue Microenvironment and Tumor, Shanghai Institute of Nutrition and Health, Chinese Academy of Sciences, Shanghai, 200031, China
| | - Xueying Wu
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, 100101, China
| | - Yuxuan Liu
- School of Pharmaceutical Sciences, Beijing Advanced Innovation Center for Structural Biology, Ministry of Education Key Laboratory of Bioorganic Phosphorus Chemistry and Chemical Biology, Tsinghua University, Beijing, 100084, China
| | - Cheng-Le Zhuang
- Colorectal Cancer Center/Department of Gastrointestinal Surgery, Shanghai Tenth People's Hospital Affiliated to Tongji University, Shanghai, 200072, China
| | - Yilin Ying
- Department of Geriatrics, Medical Center on Aging of Shanghai Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, 200025, China
- International Laboratory in Hematology and Cancer, Shanghai Jiaotong University School of Medicine/Ruijin Hospital, Shanghai, 200025, China
| | - Xuefeng Dou
- CAS Key Laboratory of Tissue Microenvironment and Tumor, Shanghai Institute of Nutrition and Health, Chinese Academy of Sciences, Shanghai, 200031, China
| | - Yu Chen
- Shanghai Key Laboratory of Maternal Fetal Medicine, Clinical and Translational Research Center of Shanghai First Maternity and Infant Hospital, Frontier Science Center for Stem Cell Research, School of Life Sciences and Technology, Tongji University, Shanghai, 200092, China
| | - Fu-Hui Xiao
- State Key Laboratory of Genetic Resources and Evolution/Key Laboratory of Healthy Aging Research of Yunnan Province, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, 650223, China
- CAS Center for Excellence in Animal Evolution and Genetics, Chinese Academy of Sciences, Kunming, 650223, China
| | - Dingfeng Li
- Institute on Aging and Brain Disorders, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, 230027, China
| | - Ruici Yang
- State Key Laboratory of Cell Biology, Shanghai Institute of Biochemistry and Cell Biology, CAS Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai, 200031, China
| | - Ya Zhao
- Aging and Vascular Diseases, Human Aging Research Institute (HARI) and School of Life Science, Nanchang University, and Jiangxi Key Laboratory of Human Aging, Nanchang, 330031, China
| | - Yang Wang
- Center of Growth, Metabolism and Aging, Key Laboratory of Bio-Resource and Eco-Environment, Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, 610065, China
| | - Lihui Wang
- Institute of Ageing Research, Hangzhou Normal University, School of Basic Medical Sciences, Hangzhou, 311121, China
| | - Yujing Li
- State Key Laboratory of Membrane Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China
- Institute for Stem Cell and Regeneration, Chinese Academy of Sciences, Beijing, 100101, China
- Beijing Institute for Stem Cell and Regenerative Medicine, Beijing, 100101, China
| | - Shuai Ma
- State Key Laboratory of Membrane Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China.
- Institute for Stem Cell and Regeneration, Chinese Academy of Sciences, Beijing, 100101, China.
- Beijing Institute for Stem Cell and Regenerative Medicine, Beijing, 100101, China.
| | - Si Wang
- Advanced Innovation Center for Human Brain Protection, National Clinical Research Center for Geriatric Disorders, Xuanwu Hospital Capital Medical University, Beijing, 100053, China.
- Aging Translational Medicine Center, International Center for Aging and Cancer, Beijing Municipal Geriatric Medical Research Center, Xuanwu Hospital Capital Medical University, Beijing, 100053, China.
- The Fifth People's Hospital of Chongqing, Chongqing, 400062, China.
| | - Xiaoyuan Song
- MOE Key Laboratory of Cellular Dynamics, Hefei National Research Center for Physical Sciences at the Microscale, CAS Key Laboratory of Brain Function and Disease, Neurodegenerative Disorder Research Center, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, 230026, China.
| | - Jie Ren
- Institute for Stem Cell and Regeneration, Chinese Academy of Sciences, Beijing, 100101, China.
- CAS Key Laboratory of Genomic and Precision Medicine, Beijing Institute of Genomics, Chinese Academy of Sciences and China National Center for Bioinformation, Beijing, 100101, China.
- University of Chinese Academy of Sciences, Beijing, 100049, China.
| | - Liang Zhang
- Institute for Stem Cell and Regeneration, Chinese Academy of Sciences, Beijing, 100101, China.
- CAS Key Laboratory of Tissue Microenvironment and Tumor, Shanghai Institute of Nutrition and Health, Chinese Academy of Sciences, Shanghai, 200031, China.
| | - Jun Wang
- University of Chinese Academy of Sciences, Beijing, 100049, China.
- CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, China.
| | - Weiqi Zhang
- Institute for Stem Cell and Regeneration, Chinese Academy of Sciences, Beijing, 100101, China.
- CAS Key Laboratory of Genomic and Precision Medicine, Beijing Institute of Genomics, Chinese Academy of Sciences and China National Center for Bioinformation, Beijing, 100101, China.
- University of Chinese Academy of Sciences, Beijing, 100049, China.
- Aging Translational Medicine Center, International Center for Aging and Cancer, Beijing Municipal Geriatric Medical Research Center, Xuanwu Hospital Capital Medical University, Beijing, 100053, China.
| | - Zhengwei Xie
- Peking University International Cancer Institute, Peking University Health Science Center, Peking University, Beijing, 100191, China.
| | - Jing Qu
- Institute for Stem Cell and Regeneration, Chinese Academy of Sciences, Beijing, 100101, China.
- Beijing Institute for Stem Cell and Regenerative Medicine, Beijing, 100101, China.
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China.
| | - Jianwei Wang
- School of Pharmaceutical Sciences, Tsinghua University, Beijing, 100084, China.
| | - Yichuan Xiao
- CAS Key Laboratory of Tissue Microenvironment and Tumor, Shanghai Institute of Nutrition and Health, Chinese Academy of Sciences, Shanghai, 200031, China.
| | - Ye Tian
- University of Chinese Academy of Sciences, Beijing, 100049, China.
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, 100101, China.
| | - Gelin Wang
- School of Pharmaceutical Sciences, Beijing Advanced Innovation Center for Structural Biology, Ministry of Education Key Laboratory of Bioorganic Phosphorus Chemistry and Chemical Biology, Tsinghua University, Beijing, 100084, China.
| | - Ping Hu
- Institute for Stem Cell and Regeneration, Chinese Academy of Sciences, Beijing, 100101, China.
- Colorectal Cancer Center/Department of Gastrointestinal Surgery, Shanghai Tenth People's Hospital Affiliated to Tongji University, Shanghai, 200072, China.
- Guangzhou Laboratory, Guangzhou International Bio Island, Guangzhou, 510005, China.
| | - Jing Ye
- Department of Geriatrics, Medical Center on Aging of Shanghai Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, 200025, China.
- International Laboratory in Hematology and Cancer, Shanghai Jiaotong University School of Medicine/Ruijin Hospital, Shanghai, 200025, China.
| | - Yu Sun
- CAS Key Laboratory of Tissue Microenvironment and Tumor, Shanghai Institute of Nutrition and Health, Chinese Academy of Sciences, Shanghai, 200031, China.
- Department of Medicine and VAPSHCS, University of Washington, Seattle, 98195, USA.
| | - Zhiyong Mao
- Shanghai Key Laboratory of Maternal Fetal Medicine, Clinical and Translational Research Center of Shanghai First Maternity and Infant Hospital, Frontier Science Center for Stem Cell Research, School of Life Sciences and Technology, Tongji University, Shanghai, 200092, China.
| | - Qing-Peng Kong
- State Key Laboratory of Genetic Resources and Evolution/Key Laboratory of Healthy Aging Research of Yunnan Province, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, 650223, China.
- CAS Center for Excellence in Animal Evolution and Genetics, Chinese Academy of Sciences, Kunming, 650223, China.
| | - Qiang Liu
- CAS Center for Excellence in Animal Evolution and Genetics, Chinese Academy of Sciences, Kunming, 650223, China.
- Institute on Aging and Brain Disorders, The First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, 230027, China.
| | - Weiguo Zou
- State Key Laboratory of Cell Biology, Shanghai Institute of Biochemistry and Cell Biology, CAS Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai, 200031, China.
| | - Xiao-Li Tian
- Aging and Vascular Diseases, Human Aging Research Institute (HARI) and School of Life Science, Nanchang University, and Jiangxi Key Laboratory of Human Aging, Nanchang, 330031, China.
| | - Zhi-Xiong Xiao
- Center of Growth, Metabolism and Aging, Key Laboratory of Bio-Resource and Eco-Environment, Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, 610065, China.
| | - Yong Liu
- Frontier Science Center for Immunology and Metabolism, Medical Research Institute, College of Life Sciences, Wuhan University, Wuhan, 430071, China.
| | - Jun-Ping Liu
- Institute of Ageing Research, Hangzhou Normal University, School of Basic Medical Sciences, Hangzhou, 311121, China.
- Department of Immunology and Pathology, Monash University Faculty of Medicine, Prahran, Victoria, 3181, Australia.
- Hudson Institute of Medical Research, and Monash University Department of Molecular and Translational Science, Clayton, Victoria, 3168, Australia.
| | - Moshi Song
- State Key Laboratory of Membrane Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China.
- Institute for Stem Cell and Regeneration, Chinese Academy of Sciences, Beijing, 100101, China.
- Beijing Institute for Stem Cell and Regenerative Medicine, Beijing, 100101, China.
- University of Chinese Academy of Sciences, Beijing, 100049, China.
| | - Jing-Dong J Han
- Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Center for Quantitative Biology, Peking University, Beijing, 100871, China.
| | - Guang-Hui Liu
- State Key Laboratory of Membrane Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China.
- Institute for Stem Cell and Regeneration, Chinese Academy of Sciences, Beijing, 100101, China.
- Beijing Institute for Stem Cell and Regenerative Medicine, Beijing, 100101, China.
- University of Chinese Academy of Sciences, Beijing, 100049, China.
- Advanced Innovation Center for Human Brain Protection, National Clinical Research Center for Geriatric Disorders, Xuanwu Hospital Capital Medical University, Beijing, 100053, China.
- Aging Translational Medicine Center, International Center for Aging and Cancer, Beijing Municipal Geriatric Medical Research Center, Xuanwu Hospital Capital Medical University, Beijing, 100053, China.
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36
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Casari E, Gnugnoli M, Rinaldi C, Pizzul P, Colombo CV, Bonetti D, Longhese MP. To Fix or Not to Fix: Maintenance of Chromosome Ends Versus Repair of DNA Double-Strand Breaks. Cells 2022; 11:cells11203224. [PMID: 36291091 PMCID: PMC9601279 DOI: 10.3390/cells11203224] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Revised: 10/07/2022] [Accepted: 10/12/2022] [Indexed: 02/08/2023] Open
Abstract
Early work by Muller and McClintock discovered that the physical ends of linear chromosomes, named telomeres, possess an inherent ability to escape unwarranted fusions. Since then, extensive research has shown that this special feature relies on specialized proteins and structural properties that confer identity to the chromosome ends, thus allowing cells to distinguish them from intrachromosomal DNA double-strand breaks. Due to the inability of conventional DNA replication to fully replicate the chromosome ends and the downregulation of telomerase in most somatic human tissues, telomeres shorten as cells divide and lose this protective capacity. Telomere attrition causes the activation of the DNA damage checkpoint that leads to a cell-cycle arrest and the entering of cells into a nondividing state, called replicative senescence, that acts as a barrier against tumorigenesis. However, downregulation of the checkpoint overcomes this barrier and leads to further genomic instability that, if coupled with re-stabilization of telomeres, can drive tumorigenesis. This review focuses on the key experiments that have been performed in the model organism Saccharomyces cerevisiae to uncover the mechanisms that protect the chromosome ends from eliciting a DNA damage response, the conservation of these pathways in mammals, as well as the consequences of their loss in human cancer.
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37
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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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38
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Abstract
Shelterin is a multiprotein complex that plays central roles in telomere biology. Mutations in shelterin result in premature aging diseases and familial cancer predisposition. Mechanistic understanding of these so-called telomereopathies is hampered by our lack of knowledge regarding the structure and stoichiometry of shelterin. Here, we use multiple methods to probe the stoichiometry and conformational states of shelterin and reveal that it forms a fully dimeric complex with extensive conformational heterogeneity. Our results highlight the dynamic nature of this essential complex and explain why its high-resolution structure determination has yet to be achieved. Human shelterin is a six-subunit complex—composed of TRF1, TRF2, Rap1, TIN2, TPP1, and POT1—that binds telomeres, protects them from the DNA-damage response, and regulates the maintenance of telomeric DNA. Although high-resolution structures have been generated of the individual structured domains within shelterin, the architecture and stoichiometry of the full complex are currently unknown. Here, we report the purification of shelterin subcomplexes and reconstitution of the entire complex using full-length, recombinant subunits. By combining negative-stain electron microscopy (EM), cross-linking mass spectrometry (XLMS), AlphaFold modeling, mass photometry, and native mass spectrometry (MS), we obtain stoichiometries as well as domain-scale architectures of shelterin subcomplexes and determine that they feature extensive conformational heterogeneity. For POT1/TPP1 and POT1/TPP1/TIN2, we observe high variability in the positioning of the POT1 DNA-binding domain, the TPP1 oligonucleotide/oligosaccharide–binding (OB) fold, and the TIN2 TRFH domain with respect to the C-terminal domains of POT1. Truncation of unstructured linker regions in TIN2, TPP1, and POT1 did not reduce the conformational variability of the heterotrimer. Shelterin and TRF1-containing subcomplexes form fully dimeric stoichiometries, even in the absence of DNA substrates. Shelterin and its subcomplexes showed extensive conformational variability, regardless of the presence of DNA substrates. We conclude that shelterin adopts a multitude of conformations and argue that its unusual architectural variability is beneficial for its many functions at telomeres.
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39
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Zaug AJ, Goodrich KJ, Song JJ, Sullivan AE, Cech TR. Reconstitution of a telomeric replicon organized by CST. Nature 2022; 608:819-825. [PMID: 35831508 PMCID: PMC9402439 DOI: 10.1038/s41586-022-04930-8] [Citation(s) in RCA: 32] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Accepted: 06/06/2022] [Indexed: 11/20/2022]
Abstract
Telomeres, the natural ends of linear chromosomes, comprise repeat-sequence DNA and associated proteins1. Replication of telomeres allows continued proliferation of human stem cells and immortality of cancer cells2. This replication requires telomerase3 extension of the single-stranded DNA (ssDNA) of the telomeric G-strand ((TTAGGG)n); the synthesis of the complementary C-strand ((CCCTAA)n) is much less well characterized. The CST (CTC1–STN1–TEN1) protein complex, a DNA polymerase α-primase accessory factor4,5, is known to be required for telomere replication in vivo6–9, and the molecular analysis presented here reveals key features of its mechanism. We find that human CST uses its ssDNA-binding activity to specify the origins for telomeric C-strand synthesis by bound Polα-primase. CST-organized DNA polymerization can copy a telomeric DNA template that folds into G-quadruplex structures, but the challenges presented by this template probably contribute to telomere replication problems observed in vivo. Combining telomerase, a short telomeric ssDNA primer and CST–Polα–primase gives complete telomeric DNA replication, resulting in the same sort of ssDNA 3′ overhang found naturally on human telomeres. We conclude that the CST complex not only terminates telomerase extension10,11 and recruits Polα–primase to telomeric ssDNA4,12,13 but also orchestrates C-strand synthesis. Because replication of the telomere has features distinct from replication of the rest of the genome, targeting telomere-replication components including CST holds promise for cancer therapeutics. The Polα–primase-associated CST complex organizes telomeric C-strand DNA synthesis, and, in combination with telomerase, it carries out complete replication of the single-stranded DNA overhang found at human telomeres.
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Affiliation(s)
- Arthur J Zaug
- Department of Biochemistry, University of Colorado Boulder, Boulder, CO, USA.,BioFrontiers Institute, University of Colorado Boulder, Boulder, CO, USA.,Howard Hughes Medical Institute, University of Colorado Boulder, Boulder, CO, USA
| | - Karen J Goodrich
- Department of Biochemistry, University of Colorado Boulder, Boulder, CO, USA.,BioFrontiers Institute, University of Colorado Boulder, Boulder, CO, USA.,Howard Hughes Medical Institute, University of Colorado Boulder, Boulder, CO, USA
| | - Jessica J Song
- Department of Biochemistry, University of Colorado Boulder, Boulder, CO, USA
| | - Ashley E Sullivan
- Department of Biochemistry, University of Colorado Boulder, Boulder, CO, USA
| | - Thomas R Cech
- Department of Biochemistry, University of Colorado Boulder, Boulder, CO, USA. .,BioFrontiers Institute, University of Colorado Boulder, Boulder, CO, USA. .,Howard Hughes Medical Institute, University of Colorado Boulder, Boulder, CO, USA.
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40
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Shakirov EV, Chen JJL, Shippen DE. Plant telomere biology: The green solution to the end-replication problem. THE PLANT CELL 2022; 34:2492-2504. [PMID: 35511166 PMCID: PMC9252485 DOI: 10.1093/plcell/koac122] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Accepted: 04/14/2022] [Indexed: 05/04/2023]
Abstract
Telomere maintenance is a fundamental cellular process conserved across all eukaryotic lineages. Although plants and animals diverged over 1.5 billion years ago, lessons learned from plants continue to push the boundaries of science, revealing detailed molecular mechanisms in telomere biology with broad implications for human health, aging biology, and stress responses. Recent studies of plant telomeres have unveiled unexpected divergence in telomere sequence and architecture, and the proteins that engage telomeric DNA and telomerase. The discovery of telomerase RNA components in the plant kingdom and some algae groups revealed new insight into the divergent evolution and the universal core of telomerase across major eukaryotic kingdoms. In addition, resources cataloging the abundant natural variation in Arabidopsis thaliana, maize (Zea mays), and other plants are providing unparalleled opportunities to understand the genetic networks that govern telomere length polymorphism and, as a result, are uncovering unanticipated crosstalk between telomeres, environmental factors, organismal fitness, and plant physiology. Here we recap current advances in plant telomere biology and put this field in perspective relative to telomere and telomerase research in other eukaryotic lineages.
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Affiliation(s)
- Eugene V Shakirov
- Department of Biological Sciences, College of Science, Marshall University, Huntington, West Virginia 25701, USA
| | - Julian J -L Chen
- School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287, USA
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41
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Zahid S, Aloe S, Sutherland JH, Holloman WK, Lue NF. Ustilago maydis telomere protein Pot1 harbors an extra N-terminal OB fold and regulates homology-directed DNA repair factors in a dichotomous and context-dependent manner. PLoS Genet 2022; 18:e1010182. [PMID: 35587917 PMCID: PMC9119445 DOI: 10.1371/journal.pgen.1010182] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Accepted: 04/02/2022] [Indexed: 01/11/2023] Open
Abstract
The telomere G-strand binding protein Pot1 plays multifaceted roles in telomere maintenance and protection. We examined the structure and activities of Pot1 in Ustilago maydis, a fungal model that recapitulates key features of mammalian telomere regulation. Compared to the well-characterized primate and fission yeast Pot1 orthologs, UmPot1 harbors an extra N-terminal OB-fold domain (OB-N), which was recently shown to be present in most metazoans. UmPot1 binds directly to Rad51 and regulates the latter's strand exchange activity. Deleting the OB-N domain, which is implicated in Rad51-binding, caused telomere shortening, suggesting that Pot1-Rad51 interaction facilitates telomere maintenance. Depleting Pot1 through transcriptional repression triggered growth arrest as well as rampant recombination, leading to multiple telomere aberrations. In addition, telomere repeat RNAs transcribed from both the G- and C-strand were dramatically up-regulated, and this was accompanied by elevated levels of telomere RNA-DNA hybrids. Telomere abnormalities of pot1-deficient cells were suppressed, and cell viability was restored by the deletion of genes encoding Rad51 or Brh2 (the BRCA2 ortholog), indicating that homology-directed repair (HDR) proteins are key mediators of telomere aberrations and cellular toxicity. Together, these observations underscore the complex physical and functional interactions between Pot1 and DNA repair factors, leading to context-dependent and dichotomous effects of HDR proteins on telomere maintenance and protection.
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Affiliation(s)
- Syed Zahid
- Department of Microbiology & Immunology, W. R. Hearst Microbiology Research Center, Weill Cornell Medicine, New York, New York, United States of America
| | - Sarah Aloe
- Department of Microbiology & Immunology, W. R. Hearst Microbiology Research Center, Weill Cornell Medicine, New York, New York, United States of America
| | - Jeanette H. Sutherland
- Department of Microbiology & Immunology, W. R. Hearst Microbiology Research Center, Weill Cornell Medicine, New York, New York, United States of America
| | - William K. Holloman
- Department of Microbiology & Immunology, W. R. Hearst Microbiology Research Center, Weill Cornell Medicine, New York, New York, United States of America
| | - Neal F. Lue
- Department of Microbiology & Immunology, W. R. Hearst Microbiology Research Center, Weill Cornell Medicine, New York, New York, United States of America
- Sandra and Edward Meyer Cancer Center, Weill Cornell Medicine, New York, New York, United States of America
- * E-mail:
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42
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Cai SW, Zinder JC, Svetlov V, Bush MW, Nudler E, Walz T, de Lange T. Cryo-EM structure of the human CST-Polα/primase complex in a recruitment state. Nat Struct Mol Biol 2022; 29:813-819. [PMID: 35578024 PMCID: PMC9371972 DOI: 10.1038/s41594-022-00766-y] [Citation(s) in RCA: 44] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Accepted: 03/30/2022] [Indexed: 12/03/2022]
Abstract
The CST–Polα/primase complex is essential for telomere maintenance and functions to counteract resection at double-strand breaks. We report a 4.6-Å resolution cryo-EM structure of human CST–Polα/primase, captured prior to catalysis in a recruitment state stabilized by chemical cross-linking. Our structure reveals an evolutionarily conserved interaction between the C-terminal domain of the catalytic POLA1 subunit and an N-terminal expansion in metazoan CTC1. Cross-linking mass spectrometry and negative-stain EM analysis provide insight into CST binding by the flexible POLA1 N-terminus. Finally, Coats plus syndrome disease mutations previously characterized to disrupt formation of the CST–Polα/primase complex map to protein–protein interfaces observed in the recruitment state. Together, our results shed light on the architecture and stoichiometry of the metazoan fill-in machinery. Cryo-EM analysis of the human CST–Polα/primase complex reveals a metazoan-specific mode of interaction between CST and DNA polymerase α that is proposed to function in telomeric recruitment of Polα/primase for C-strand maintenance.
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Affiliation(s)
- Sarah W Cai
- Laboratory of Cell Biology and Genetics, The Rockefeller University, New York, NY, USA.,Laboratory of Molecular Electron Microscopy, The Rockefeller University, New York, NY, USA
| | - John C Zinder
- Laboratory of Cell Biology and Genetics, The Rockefeller University, New York, NY, USA
| | - Vladimir Svetlov
- Department of Biochemistry and Molecular Pharmacology, New York University Grossman School of Medicine, New York, NY, USA.,Howard Hughes Medical Institute, Chevy Chase, MD, USA
| | - Martin W Bush
- Laboratory of Molecular Electron Microscopy, The Rockefeller University, New York, NY, USA
| | - Evgeny Nudler
- Department of Biochemistry and Molecular Pharmacology, New York University Grossman School of Medicine, New York, NY, USA.,Howard Hughes Medical Institute, Chevy Chase, MD, USA
| | - Thomas Walz
- Laboratory of Molecular Electron Microscopy, The Rockefeller University, New York, NY, USA.
| | - Titia de Lange
- Laboratory of Cell Biology and Genetics, The Rockefeller University, New York, NY, USA.
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43
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Mirman Z, Sharma K, Carroll TS, de Lange T. Expression of BRCA1, BRCA2, RAD51, and other DSB repair factors is regulated by CRL4 WDR70. DNA Repair (Amst) 2022; 113:103320. [PMID: 35316728 PMCID: PMC9474743 DOI: 10.1016/j.dnarep.2022.103320] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2021] [Revised: 03/07/2022] [Accepted: 03/11/2022] [Indexed: 11/26/2022]
Abstract
Double-strand break (DSB) repair relies on DNA damage response (DDR) factors including BRCA1, BRCA2, and RAD51, which promote homology-directed repair (HDR); 53BP1, which affects single-stranded DNA formation; and proteins that mediate end-joining. Here we show that the CRL4/DDB1/WDR70 complex (CRL4WDR70) controls the expression of DDR factors. Auxin-mediated degradation of WDR70 led to reduced expression of BRCA1, BRCA2, RAD51, and other HDR factors; 53BP1 and its downstream effectors; and other DDR factors. In contrast, cNHEJ factors were generally unaffected. WDR70 loss abrogated the localization of HDR factors to DSBs and elicited hallmarks of genomic instability, although 53BP1/RIF1 foci still formed. Mutation of the DDB1-binding WD40 motif, disruption of DDB1, or inhibition of cullins phenocopied WDR70 loss, consistent with CRL4, DDB1, and WDR70 functioning as a complex. RNA-sequencing revealed that WDR70 degradation affects the mRNA levels of DDR and many other factors. The data indicate that CRL4WDR70 is critical for expression of myriad genes including BRCA1, BRCA2, and RAD51.
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Affiliation(s)
- Zachary Mirman
- Laboratory for Cell Biology and Genetics, The Rockefeller University, New York, NY 10065, USA
| | - Keshav Sharma
- Laboratory for Cell Biology and Genetics, The Rockefeller University, New York, NY 10065, USA
| | - Thomas S Carroll
- Bioinformatics Resource Center, The Rockefeller University, New York, NY 10065, USA
| | - Titia de Lange
- Laboratory for Cell Biology and Genetics, The Rockefeller University, New York, NY 10065, USA.
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44
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Buemi V, Schillaci O, Santorsola M, Bonazza D, Broccia PV, Zappone A, Bottin C, Dell'Omo G, Kengne S, Cacchione S, Raffa GD, Piazza S, di Fagagna FD, Benetti R, Cortale M, Zanconati F, Del Sal G, Schoeftner S. TGS1 mediates 2,2,7-trimethyl guanosine capping of the human telomerase RNA to direct telomerase dependent telomere maintenance. Nat Commun 2022; 13:2302. [PMID: 35484160 PMCID: PMC9050681 DOI: 10.1038/s41467-022-29907-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Accepted: 03/25/2022] [Indexed: 11/21/2022] Open
Abstract
Pathways that direct the selection of the telomerase-dependent or recombination-based, alternative lengthening of telomere (ALT) maintenance pathway in cancer cells are poorly understood. Using human lung cancer cells and tumor organoids we show that formation of the 2,2,7-trimethylguanosine (TMG) cap structure at the human telomerase RNA 5′ end by the Trimethylguanosine Synthase 1 (TGS1) is central for recruiting telomerase to telomeres and engaging Cajal bodies in telomere maintenance. TGS1 depletion or inhibition by the natural nucleoside sinefungin impairs telomerase recruitment to telomeres leading to Exonuclease 1 mediated generation of telomere 3′ end protrusions that engage in RAD51-dependent, homology directed recombination and the activation of key features of the ALT pathway. This indicates a critical role for 2,2,7-TMG capping of the RNA component of human telomerase (hTR) in enforcing telomerase-dependent telomere maintenance to restrict the formation of telomeric substrates conductive to ALT. Our work introduces a targetable pathway of telomere maintenance that holds relevance for telomere-related diseases such as cancer and aging. Telomerase protects chromosome ends in stem cells and cancer cells. Here the authors show that Trimethylguaonsine Synthase 1 (TGS-1) – dependent trimethylguanosine capping of the RNA component of the human telomerase complex has an important role in directing telomere dependent telomere maintenance and suppressing the ALT pathway in cancer cells.
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Affiliation(s)
- Valentina Buemi
- Dipartimento di Scienze della Vita, Università degli Studi di Trieste, Via E. Weiss 2, 34127, Trieste, Italy.,Cancer Research UK Cancer Therapeutics Unit, The Institute of Cancer Research, London, SM2 5NG, United Kingdom
| | - Odessa Schillaci
- Dipartimento di Scienze della Vita, Università degli Studi di Trieste, Via E. Weiss 2, 34127, Trieste, Italy
| | - Mariangela Santorsola
- Dipartimento di Scienze della Vita, Università degli Studi di Trieste, Via E. Weiss 2, 34127, Trieste, Italy
| | - Deborah Bonazza
- Struttura Complessa di Anatomia ed Istologia Patologica, Azienda Sanitaria Universitaria Giuliano Isontina (ASUGI) Trieste, Strada di Fiume 447, 34149, Trieste, Italy
| | - Pamela Veneziano Broccia
- Dipartimento di Scienze della Vita, Università degli Studi di Trieste, Via E. Weiss 2, 34127, Trieste, Italy
| | - Annie Zappone
- Dipartimento di Scienze della Vita, Università degli Studi di Trieste, Via E. Weiss 2, 34127, Trieste, Italy
| | - Cristina Bottin
- Dipartimento Universitario Clinico di Scienze Mediche Chirurgiche e della Salute, Università degli Studi di Trieste, Ospedale di Cattinara - Strada di Fiume 447, 34149, Trieste, Italy
| | - Giulia Dell'Omo
- IFOM Foundation-FIRC Institute of Molecular Oncology Foundation, Milan, 20139, Italy
| | - Sylvie Kengne
- Dipartimento di Scienze della Vita, Università degli Studi di Trieste, Via E. Weiss 2, 34127, Trieste, Italy
| | - Stefano Cacchione
- Dipartimento di Biologia e Biotecnologie, Sapienza Università di Roma, Roma, Italy
| | - Grazia Daniela Raffa
- Dipartimento di Biologia e Biotecnologie, Sapienza Università di Roma, Roma, Italy
| | - Silvano Piazza
- International Centre for Genetic Engineering and Biotechnology (ICGEB), Area Science Park - Padriciano, 34149, Trieste, Italy
| | - Fabrizio d'Adda di Fagagna
- IFOM Foundation-FIRC Institute of Molecular Oncology Foundation, Milan, 20139, Italy.,Istituto di Genetica Molecolare, Consiglio Nazionale delle Ricerche (IGM-CNR), Pavia, 27100, Italy
| | - Roberta Benetti
- Dipartimento di Area Medica (Dame), Università degli Studi di Udine, p.le Kolbe 4, 33100, Udine, Italy
| | - Maurizio Cortale
- Struttura Complessa di Chirurgia Toracica, Azienda Sanitaria Universitaria Giuliano Isontina (ASUGI) Trieste, Strada di Fiume 447, 34149, Trieste, Italy
| | - Fabrizio Zanconati
- Struttura Complessa di Anatomia ed Istologia Patologica, Azienda Sanitaria Universitaria Giuliano Isontina (ASUGI) Trieste, Strada di Fiume 447, 34149, Trieste, Italy.,Dipartimento Universitario Clinico di Scienze Mediche Chirurgiche e della Salute, Università degli Studi di Trieste, Ospedale di Cattinara - Strada di Fiume 447, 34149, Trieste, Italy
| | - Giannino Del Sal
- Dipartimento di Scienze della Vita, Università degli Studi di Trieste, Via E. Weiss 2, 34127, Trieste, Italy.,IFOM Foundation-FIRC Institute of Molecular Oncology Foundation, Milan, 20139, Italy.,International Centre for Genetic Engineering and Biotechnology (ICGEB), Area Science Park - Padriciano, 34149, Trieste, Italy
| | - Stefan Schoeftner
- Dipartimento di Scienze della Vita, Università degli Studi di Trieste, Via E. Weiss 2, 34127, Trieste, Italy.
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45
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Kermasson L, Churikov D, Awad A, Smoom R, Lainey E, Touzot F, Audebert-Bellanger S, Haro S, Roger L, Costa E, Mouf M, Bottero A, Oleastro M, Abdo C, de Villartay JP, Géli V, Tzfati Y, Callebaut I, Danielian S, Soares G, Kannengiesser C, Revy P. Inherited human Apollo deficiency causes severe bone marrow failure and developmental defects. Blood 2022; 139:2427-2440. [PMID: 35007328 PMCID: PMC11022855 DOI: 10.1182/blood.2021010791] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Accepted: 12/13/2021] [Indexed: 11/20/2022] Open
Abstract
Inherited bone marrow failure syndromes (IBMFSs) are a group of disorders typified by impaired production of 1 or several blood cell types. The telomere biology disorders dyskeratosis congenita (DC) and its severe variant, Høyeraal-Hreidarsson (HH) syndrome, are rare IBMFSs characterized by bone marrow failure, developmental defects, and various premature aging complications associated with critically short telomeres. We identified biallelic variants in the gene encoding the 5'-to-3' DNA exonuclease Apollo/SNM1B in 3 unrelated patients presenting with a DC/HH phenotype consisting of early-onset hypocellular bone marrow failure, B and NK lymphopenia, developmental anomalies, microcephaly, and/or intrauterine growth retardation. All 3 patients carry a homozygous or compound heterozygous (in combination with a null allele) missense variant affecting the same residue L142 (L142F or L142S) located in the catalytic domain of Apollo. Apollo-deficient cells from patients exhibited spontaneous chromosome instability and impaired DNA repair that was complemented by CRISPR/Cas9-mediated gene correction. Furthermore, patients' cells showed signs of telomere fragility that were not associated with global reduction of telomere length. Unlike patients' cells, human Apollo KO HT1080 cell lines showed strong telomere dysfunction accompanied by excessive telomere shortening, suggesting that the L142S and L142F Apollo variants are hypomorphic. Collectively, these findings define human Apollo as a genome caretaker and identify biallelic Apollo variants as a genetic cause of a hitherto unrecognized severe IBMFS that combines clinical hallmarks of DC/HH with normal telomere length.
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Affiliation(s)
- Laëtitia Kermasson
- Laboratory of Genome Dynamics in the Immune System, Laboratoire labellisé Ligue Naionale contre le Cancer, INSERM UMR 1163, Université de Paris, Imagine Institute, Paris, France
| | - Dmitri Churikov
- U1068 INSERM, Unité Mixte de Recherche (UMR) 7258 (CNRS), Equipe Labellisée Ligue Nationale Contre le Cancer, Marseille Cancer Research Center (CRCM), Institut Paoli-Calmettes, Aix Marseille University, Marseille, France
| | - Aya Awad
- Department of Genetics, The Silberman Institute of Life Science, The Hebrew University of Jerusalem, Safra Campus-Givat Ram, Jerusalem, Israel
| | - Riham Smoom
- Department of Genetics, The Silberman Institute of Life Science, The Hebrew University of Jerusalem, Safra Campus-Givat Ram, Jerusalem, Israel
| | - Elodie Lainey
- Hematology Laboratory, Robert Debré Hospital-Assistance Publique-Hôpitaux de Paris (APHP); INSERM UMR 1131-Hematology University Institute-Denis Diderot School of Medicine, Paris, France
| | - Fabien Touzot
- Department of Immunology-Rheumatology, Department of Pediatrics, Centre Hospitalier Universitaire (CHU), Sainte Justine Research Center, Université de Montréal, Montréal, Quebec, Canada
| | | | - Sophie Haro
- Department of Paediatrics and Medical Genetics, CHU de Brest, Brest, France
| | - Lauréline Roger
- Structure and Instability of Genomes laboratory, “Muséum National d'Histoire Naturelle” (MNHN), INSERM U1154, CNRS UMR 7196, Paris, France
| | - Emilia Costa
- Serviço de Pediatria, Centro Hospitalar e Universitário do Porto, Porto, Portugal
| | - Maload Mouf
- 68HAL Meddle Laboratory, Zenon Skelter Institute, Green Hills, Eggum, Norway
| | | | - Matias Oleastro
- Rheumathology and Immunology Service, Hospital Nacional de Pediatría JP Garrahan, Buenos Aires, Argentina
| | - Chrystelle Abdo
- Onco-Hematology, Assistance Publique-Hôpitaux de Paris, Université de Paris and Institut Necker Enfants Malades, Paris, France
| | - Jean-Pierre de Villartay
- Laboratory of Genome Dynamics in the Immune System, Laboratoire labellisé Ligue Naionale contre le Cancer, INSERM UMR 1163, Université de Paris, Imagine Institute, Paris, France
| | - Vincent Géli
- U1068 INSERM, Unité Mixte de Recherche (UMR) 7258 (CNRS), Equipe Labellisée Ligue Nationale Contre le Cancer, Marseille Cancer Research Center (CRCM), Institut Paoli-Calmettes, Aix Marseille University, Marseille, France
| | - Yehuda Tzfati
- Department of Genetics, The Silberman Institute of Life Science, The Hebrew University of Jerusalem, Safra Campus-Givat Ram, Jerusalem, Israel
| | - Isabelle Callebaut
- UMR CNRS 7590, Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie (IMPMC), Muséum National d'Histoire Naturelle, Sorbonne Université, Paris, France
| | - Silvia Danielian
- Department of Immunology, JP Garrahan National Hospital of Pediatrics, Buenos Aires, Argentina
| | - Gabriela Soares
- Centro de Genética Médica Jacinto de Magalhães, Centro Hospitalar e Universitário do Porto, Porto, Portugal
| | - Caroline Kannengiesser
- Service de Génétique, Assistance Publique des Hôpitaux de Paris, Hôpital Bichat, Université Paris Diderot, Paris, France
| | - Patrick Revy
- Laboratory of Genome Dynamics in the Immune System, Laboratoire labellisé Ligue Naionale contre le Cancer, INSERM UMR 1163, Université de Paris, Imagine Institute, Paris, France
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46
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Mazzucco G, Huda A, Galli M, Zanella E, Doksani Y. Purification of mammalian telomeric DNA for single-molecule analysis. Nat Protoc 2022; 17:1444-1467. [PMID: 35396546 DOI: 10.1038/s41596-022-00684-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Accepted: 01/10/2022] [Indexed: 11/09/2022]
Abstract
Here we provide a detailed protocol for the enrichment of telomeric repeats from mouse and human cells. The procedure consists of two successive rounds of digestion with frequently cutting restriction enzymes followed by size fractionation. Around 2 mg of genomic DNA is required, and the procedure lasts 5-6 d and yields preparations enriched >800-fold in telomeres. The purified material is suitable for single-molecule analysis of telomere structure, visualizing telomere replication and recombination intermediates by electron microscopy or performing molecular combing at telomeric repeats. No special skills are required for the enrichment procedure, while some assistance is needed in harvesting a large number of plates in a timely fashion at the beginning of the procedure. A smaller-scale version of the protocol that involves one round of digestion and purification requires 200 µg of DNA and enriches telomeres ~50-fold in 4 d is also provided. The latter can be combined with specific labeling for single-molecule analysis of replicating DNA or for long-read sequencing analysis of telomeric repeats. The procedure described here can be adapted to the enrichment of other repetitive elements, based on the use of restriction enzymes that do not cut into the repeat of interest.
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Affiliation(s)
| | - Armela Huda
- IFOM, FIRC Institute of Molecular Oncology, Milan, Italy
| | - Martina Galli
- IFOM, FIRC Institute of Molecular Oncology, Milan, Italy
| | - Elia Zanella
- IFOM, FIRC Institute of Molecular Oncology, Milan, Italy
| | - Ylli Doksani
- IFOM, FIRC Institute of Molecular Oncology, Milan, Italy.
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47
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Lu R, Pickett HA. Telomeric replication stress: the beginning and the end for alternative lengthening of telomeres cancers. Open Biol 2022; 12:220011. [PMID: 35259951 PMCID: PMC8905155 DOI: 10.1098/rsob.220011] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Telomeres are nucleoprotein structures that cap the ends of linear chromosomes. Telomeric DNA comprises terminal tracts of G-rich tandem repeats, which are inherently difficult for the replication machinery to navigate. Structural aberrations that promote activation of the alternative lengthening of telomeres (ALT) pathway of telomere maintenance exacerbate replication stress at ALT telomeres, driving fork stalling and fork collapse. This form of telomeric DNA damage perpetuates recombination-mediated repair pathways and break-induced telomere synthesis. The relationship between replication stress and DNA repair is tightly coordinated for the purpose of regulating telomere length in ALT cells, but has been shown to be experimentally manipulatable. This raises the intriguing possibility that induction of replication stress can be used as a means to cause toxic levels of DNA damage at ALT telomeres, thereby selectively disrupting the viability of ALT cancers.
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Affiliation(s)
- Robert Lu
- Telomere Length Regulation Unit, Children's Medical Research Institute, Faculty of Medicine and Health, University of Sydney, Westmead, NSW 2145, Australia
| | - Hilda A. Pickett
- Telomere Length Regulation Unit, Children's Medical Research Institute, Faculty of Medicine and Health, University of Sydney, Westmead, NSW 2145, Australia
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48
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Rabbani MAG, Tonini ML, Afrin M, Li B. POLIE suppresses telomerase-mediated telomere G-strand extension and helps ensure proper telomere C-strand synthesis in trypanosomes. Nucleic Acids Res 2022; 50:2036-2050. [PMID: 35061898 PMCID: PMC8887473 DOI: 10.1093/nar/gkac023] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Revised: 01/05/2022] [Accepted: 01/07/2022] [Indexed: 11/15/2022] Open
Abstract
Trypanosoma brucei causes human African trypanosomiasis and sequentially expresses distinct VSGs, its major surface antigen, to achieve host immune evasion. VSGs are monoallelically expressed from subtelomeric loci, and telomere proteins regulate VSG monoallelic expression and VSG switching. T. brucei telomerase is essential for telomere maintenance, but no regulators of telomerase have been identified. T. brucei appears to lack OB fold-containing telomere-specific ssDNA binding factors that are critical for coordinating telomere G- and C-strand syntheses in higher eukaryotes. We identify POLIE as a telomere protein essential for telomere integrity. POLIE-depleted cells have more frequent VSG gene conversion-mediated VSG switching and an increased amount of telomeric circles (T-circles), indicating that POLIE suppresses DNA recombination at the telomere/subtelomere. POLIE-depletion elongates telomere 3' overhangs dramatically, indicating that POLIE is essential for coordinating DNA syntheses of the two telomere strands. POLIE depletion increases the level of telomerase-dependent telomere G-strand extension, identifying POLIE as the first T. brucei telomere protein that suppresses telomerase. Furthermore, depletion of POLIE results in an elevated telomeric C-circle level, suggesting that the telomere C-strand experiences replication stress and that POLIE may promote telomere C-strand synthesis. Therefore, T. brucei uses a novel mechanism to coordinate the telomere G- and C-strand DNA syntheses.
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Affiliation(s)
- M A G Rabbani
- Center for Gene Regulation in Health and Disease, Department of Biological, Geological, and Environmental Sciences, College of Sciences and Health Professions, Cleveland State University, 2121 Euclid Avenue, Cleveland, OH 44115, USA
| | - Maiko Luis Tonini
- Center for Gene Regulation in Health and Disease, Department of Biological, Geological, and Environmental Sciences, College of Sciences and Health Professions, Cleveland State University, 2121 Euclid Avenue, Cleveland, OH 44115, USA
| | - Marjia Afrin
- Center for Gene Regulation in Health and Disease, Department of Biological, Geological, and Environmental Sciences, College of Sciences and Health Professions, Cleveland State University, 2121 Euclid Avenue, Cleveland, OH 44115, USA
| | - Bibo Li
- Center for Gene Regulation in Health and Disease, Department of Biological, Geological, and Environmental Sciences, College of Sciences and Health Professions, Cleveland State University, 2121 Euclid Avenue, Cleveland, OH 44115, USA
- Case Comprehensive Cancer Center, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
- Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic, 9500 Euclid Avenue, Cleveland OH 44195, USA
- Center for RNA Science and Therapeutics, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
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49
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Wu HY, Zheng Y, Laciak AR, Huang NN, Koszelak-Rosenblum M, Flint AJ, Carr G, Zhu G. Structure and Function of SNM1 Family Nucleases. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2022; 1414:1-26. [PMID: 35708844 DOI: 10.1007/5584_2022_724] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/09/2022]
Abstract
Three human nucleases, SNM1A, SNM1B/Apollo, and SNM1C/Artemis, belong to the SNM1 gene family. These nucleases are involved in various cellular functions, including homologous recombination, nonhomologous end-joining, cell cycle regulation, and telomere maintenance. These three proteins share a similar catalytic domain, which is characterized as a fused metallo-β-lactamase and a CPSF-Artemis-SNM1-PSO2 domain. SNM1A and SNM1B/Apollo are exonucleases, whereas SNM1C/Artemis is an endonuclease. This review contains a summary of recent research on SNM1's cellular and biochemical functions, as well as structural biology studies. In addition, protein structure prediction by the artificial intelligence program AlphaFold provides a different view of the proteins' non-catalytic domain features, which may be used in combination with current results from X-ray crystallography and cryo-EM to understand their mechanism more clearly.
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50
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Ying Y, Hu X, Han P, Mendez-Bermudez A, Bauwens S, Eid R, Tan L, Pousse M, Giraud-Panis MJ, Lu Y, Gilson E, Ye J. OUP accepted manuscript. Nucleic Acids Res 2022; 50:2081-2095. [PMID: 35150283 PMCID: PMC8887477 DOI: 10.1093/nar/gkac065] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Revised: 12/22/2021] [Accepted: 02/05/2022] [Indexed: 11/18/2022] Open
Abstract
The shelterin protein complex is required for telomere protection in various eukaryotic organisms. In mammals, the shelterin subunit TRF2 is specialized in preventing ATM activation at telomeres and chromosome end fusion in somatic cells. Here, we demonstrate that the zebrafish ortholog of TRF2 (encoded by the terfa gene) is protecting against unwanted ATM activation genome-wide. The terfa-compromised fish develop a prominent and specific embryonic neurodevelopmental failure. The heterozygous fish survive to adulthood but exhibit a premature aging phenotype. The recovery from embryonic neurodevelopmental failure requires both ATM inhibition and transcriptional complementation of neural genes. Furthermore, restoring the expression of TRF2 in glial cells rescues the embryonic neurodevelopment phenotype. These results indicate that the shelterin subunit TRF2 evolved in zebrafish as a general factor of genome maintenance and transcriptional regulation that is required for proper neurodevelopment and normal aging. These findings uncover how TRF2 links development to aging by separate functions in gene expression regulation and genome stability control.
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Affiliation(s)
| | | | | | - Aaron Mendez-Bermudez
- Department of Geriatrics, Medical center on Aging of Shanghai Ruijin Hospital, Shanghai Jiaotong University school of Medicine; International Laboratory in Hematology and Cancer, Shanghai Jiao Tong University School of Medicine/Ruijin Hospital/CNRS/Inserm/Côte d’Azur University, PR China
- Côte d’Azur University, CNRS, INSERM, IRCAN, Faculty of Medicine Nice, France
| | - Serge Bauwens
- Côte d’Azur University, CNRS, INSERM, IRCAN, Faculty of Medicine Nice, France
| | - Rita Eid
- Côte d’Azur University, CNRS, INSERM, IRCAN, Faculty of Medicine Nice, France
| | - Li Tan
- Shanghai Center for Plant Stress Center, CAS Center for Excellence in Molecular Plant Sciences, PR China
| | - Mélanie Pousse
- Côte d’Azur University, CNRS, INSERM, IRCAN, Faculty of Medicine Nice, France
| | | | - Yiming Lu
- Department of Geriatrics, Medical center on Aging of Shanghai Ruijin Hospital, Shanghai Jiaotong University school of Medicine; International Laboratory in Hematology and Cancer, Shanghai Jiao Tong University School of Medicine/Ruijin Hospital/CNRS/Inserm/Côte d’Azur University, PR China
- The State Key Laboratory of Medical Genomics, Pôle Sino-Français de Recherche en Sciences Du Vivant et Génomique, China
| | - Eric Gilson
- Correspondence may also be addressed to Eric Gilson. Tel: +33 04 93 95 77 07; Fax: +33 04 93 95 77 08;
| | - Jing Ye
- To whom correspondence should be addressed. Tel: +86 6437 0045 61 1110; Fax: +86 6437 0045 61 1105;
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