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Park M, Lee DE, Hong Y, Suh JK, Lee JA, Kim M, Park HJ. Telomere Length in Adolescent and Young Adult Survivors of Childhood Cancer. Cancers (Basel) 2024; 16:2344. [PMID: 39001406 PMCID: PMC11240481 DOI: 10.3390/cancers16132344] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2024] [Revised: 06/21/2024] [Accepted: 06/23/2024] [Indexed: 07/16/2024] Open
Abstract
We examined the leukocyte relative telomere length (RTL) in Korean adolescent and young adult (AYA) survivors of childhood cancer and evaluated the association of leukocyte RTL with multiple factors, including malignancy type, cancer treatment, age, and chronic health conditions (CHCs). Eighty-eight AYA survivors of childhood cancer with a median follow-up period of 73 months were recruited. RTL in pediatric cancer survivors was not significantly shorter than the predicted value for age-matched references. Neither age at diagnosis nor duration of therapy influenced the RTL. Among the 43 patients with hematologic malignancies, those who underwent allogeneic hematopoietic stem cell transplantation (HSCT) showed a significant shortening of the RTL compared with those who did not (p = 0.039). Among the 15 patients who underwent allogeneic HSCT, those who developed acute graft-versus-host disease (GVHD) of grade II or higher had significantly shorter RTL than those who did not (p = 0.012). Patients with grade II CHCs had significantly shorter RTL than those without CHCs or with grade I CHCs (p = 0.001). Survivors with ≥2 CHCs also exhibited shorter RTL (p = 0.027). Overall, pediatric cancer survivors had similar telomere lengths compared to age-matched references. HSCT recipients and patients with severe or multiple CHCs had shorter telomeres. GVHD augmented telomere attrition in HSCT recipients.
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Affiliation(s)
- Meerim Park
- Department of Pediatrics, Center for Pediatric Cancer, National Cancer Center, Goyang 10408, Republic of Korea
| | - Dong-Eun Lee
- Biostatic Collaboration Team, Research Institute, National Cancer Center, Goyang 10408, Republic of Korea
| | - Yuna Hong
- Catholic Genetic Laboratory Center, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul 06591, Republic of Korea
| | - Jin Kyung Suh
- Department of Pediatrics, Center for Pediatric Cancer, National Cancer Center, Goyang 10408, Republic of Korea
| | - Jun Ah Lee
- Department of Pediatrics, Center for Pediatric Cancer, National Cancer Center, Goyang 10408, Republic of Korea
| | - Myungshin Kim
- Department of Laboratory Medicine, College of Medicine, The Catholic University of Korea, Seoul 06591, Republic of Korea
| | - Hyeon Jin Park
- Department of Pediatrics, Center for Pediatric Cancer, National Cancer Center, Goyang 10408, Republic of Korea
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2
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Herr LM, Schaffer ED, Fuchs KF, Datta A, Brosh RM. Replication stress as a driver of cellular senescence and aging. Commun Biol 2024; 7:616. [PMID: 38777831 PMCID: PMC11111458 DOI: 10.1038/s42003-024-06263-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2023] [Accepted: 04/29/2024] [Indexed: 05/25/2024] Open
Abstract
Replication stress refers to slowing or stalling of replication fork progression during DNA synthesis that disrupts faithful copying of the genome. While long considered a nexus for DNA damage, the role of replication stress in aging is under-appreciated. The consequential role of replication stress in promotion of organismal aging phenotypes is evidenced by an extensive list of hereditary accelerated aging disorders marked by molecular defects in factors that promote replication fork progression and operate uniquely in the replication stress response. Additionally, recent studies have revealed cellular pathways and phenotypes elicited by replication stress that align with designated hallmarks of aging. Here we review recent advances demonstrating the role of replication stress as an ultimate driver of cellular senescence and aging. We discuss clinical implications of the intriguing links between cellular senescence and aging including application of senotherapeutic approaches in the context of replication stress.
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Affiliation(s)
- Lauren M Herr
- Helicases and Genomic Integrity Section, Translational Gerontology Branch, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA
| | - Ethan D Schaffer
- Helicases and Genomic Integrity Section, Translational Gerontology Branch, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA
| | - Kathleen F Fuchs
- Helicases and Genomic Integrity Section, Translational Gerontology Branch, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA
| | - Arindam Datta
- Helicases and Genomic Integrity Section, Translational Gerontology Branch, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA.
- Department of Cancer Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
| | - Robert M Brosh
- Helicases and Genomic Integrity Section, Translational Gerontology Branch, National Institute on Aging, National Institutes of Health, Baltimore, MD, USA.
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3
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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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4
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Muyas F, Rodriguez MJG, Cascão R, Afonso A, Sauer CM, Faria CC, Cortés-Ciriano I, Flores I. The ALT pathway generates telomere fusions that can be detected in the blood of cancer patients. Nat Commun 2024; 15:82. [PMID: 38167290 PMCID: PMC10762111 DOI: 10.1038/s41467-023-44287-8] [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: 01/28/2023] [Accepted: 12/07/2023] [Indexed: 01/05/2024] Open
Abstract
Telomere fusions (TFs) can trigger the accumulation of oncogenic alterations leading to malignant transformation and drug resistance. Despite their relevance in tumour evolution, our understanding of the patterns and consequences of TFs in human cancers remains limited. Here, we characterize the rates and spectrum of somatic TFs across >30 cancer types using whole-genome sequencing data. TFs are pervasive in human tumours with rates varying markedly across and within cancer types. In addition to end-to-end fusions, we find patterns of TFs that we mechanistically link to the activity of the alternative lengthening of telomeres (ALT) pathway. We show that TFs can be detected in the blood of cancer patients, which enables cancer detection with high specificity and sensitivity even for early-stage tumours and cancers of high unmet clinical need. Overall, we report a genomic footprint that enables characterization of the telomere maintenance mechanism of tumours and liquid biopsy analysis.
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Affiliation(s)
- Francesc Muyas
- European Molecular Biology Laboratory, European Bioinformatics Institute, Hinxton, Cambridge, CB10 1SD, UK
| | | | - Rita Cascão
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal
| | - Angela Afonso
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal
| | - Carolin M Sauer
- European Molecular Biology Laboratory, European Bioinformatics Institute, Hinxton, Cambridge, CB10 1SD, UK
| | - Claudia C Faria
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal
- Department of Neurosurgery, Hospital de Santa Maria, Centro Hospitalar Universitário Lisboa Norte (CHULN), Lisboa, Portugal
| | - Isidro Cortés-Ciriano
- European Molecular Biology Laboratory, European Bioinformatics Institute, Hinxton, Cambridge, CB10 1SD, UK.
| | - Ignacio Flores
- Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC), Madrid, 28029, Spain.
- Centro de Biologia Molecular Severo Ochoa, CSIC-UAM, Cantoblanco, Madrid, 28049, Spain.
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5
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Reiss M, Keegan J, Aldrich A, Lyons SM, Flynn RL. The exoribonuclease XRN2 mediates degradation of the long non-coding telomeric RNA TERRA. FEBS Lett 2023; 597:1818-1836. [PMID: 37191774 PMCID: PMC10524182 DOI: 10.1002/1873-3468.14639] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Revised: 05/01/2023] [Accepted: 05/05/2023] [Indexed: 05/17/2023]
Abstract
The telomeric repeat-containing RNA, TERRA, associates with both telomeric DNA and telomeric proteins, often forming RNA:DNA hybrids (R-loops). TERRA is most abundant in cancer cells utilizing the alternative lengthening of telomeres (ALT) pathway for telomere maintenance, suggesting that persistent TERRA R-loops may contribute to activation of the ALT mechanism. Therefore, we sought to identify the enzyme(s) that regulate TERRA metabolism in mammalian cells. Here, we identify that the 5'-3' exoribonuclease XRN2 regulates the stability of TERRA RNA. Moreover, while stabilization of TERRA alone was insufficient to drive ALT, depletion of XRN2 in ALT-positive cells led to a significant increase in TERRA R-loops and exacerbated ALT activity. Together, our findings highlight XRN2 as a key determinant of TERRA metabolism and telomere stability in cancer cells that rely on the ALT pathway.
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Affiliation(s)
- Matthew Reiss
- Departments of Pharmacology and Experimental Therapeutics, and Medicine, Cancer Center, Boston University Chobanian & Avedisian School of Medicine, Boston, MA 02118, USA
| | - Joshua Keegan
- Departments of Pharmacology and Experimental Therapeutics, and Medicine, Cancer Center, Boston University Chobanian & Avedisian School of Medicine, Boston, MA 02118, USA
| | - Anne Aldrich
- Departments of Biochemistry and Cell Biology, Boston University Chobanian & Avedisian School of Medicine, Boston, MA 02118, USA
| | - Shawn M. Lyons
- Departments of Biochemistry and Cell Biology, Boston University Chobanian & Avedisian School of Medicine, Boston, MA 02118, USA
| | - Rachel Litman Flynn
- Departments of Pharmacology and Experimental Therapeutics, and Medicine, Cancer Center, Boston University Chobanian & Avedisian School of Medicine, Boston, MA 02118, USA
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6
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Chakraborty A, Roy S, Hande MP, Banerjee B. Telomere attrition and genomic instability in unexplained recurrent pregnancy loss in humans: A preliminary study. MUTATION RESEARCH. GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2023; 886:503580. [PMID: 36868694 DOI: 10.1016/j.mrgentox.2022.503580] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Revised: 12/20/2022] [Accepted: 12/22/2022] [Indexed: 12/28/2022]
Abstract
Genome instability is defined as an elevated rate of DNA damage and mutations as a result of exposure to potential direct and indirect mutagens. This current investigation was designed to elucidate the genomic instability among couples experiencing unexplained recurrent pregnancy loss (uRPL). A cohort of 1272 individuals with history of unexplained RPL with normal karyotype was retrospectively screened for levels of intracellular ROS production, baseline genomic instability and telomere functionality. The experimental outcome was compared with 728 fertile control individuals. In this study, it was perceived that individuals with uRPL exhibited higher intracellular oxidative stress, along with higher basal levels of genomic instability as compared with the fertile controls. This observation elucidates the role of genomic instability as well as involvement of telomeres in cases of uRPL. It was also observed that higher oxidative stress might be associated with DNA damage and telomere dysfunction resulting in genomic instability among subjects with unexplained RPL. This study highlighted the assessment of genomic instability status in individuals experiencing uRPL.
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Affiliation(s)
- Abhik Chakraborty
- School of Biotechnology, KIIT Deemed to be University, Bhubaneswar, Odisha 751024, India; inDNA Center for Research and Innovations in Molecular Diagnostics, inDNA Life Sciences Private Limited, Bhubaneswar, Odisha 751024, India
| | - Souvick Roy
- School of Biotechnology, KIIT Deemed to be University, Bhubaneswar, Odisha 751024, India; inDNA Center for Research and Innovations in Molecular Diagnostics, inDNA Life Sciences Private Limited, Bhubaneswar, Odisha 751024, India
| | - Manoor Prakash Hande
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117593, Singapore; VIT University, Vellore 632014, India; Department of Applied Zoology, Mangalore University, Mangalore, Karnataka 574199, India
| | - Birendranath Banerjee
- inDNA Center for Research and Innovations in Molecular Diagnostics, inDNA Life Sciences Private Limited, Bhubaneswar, Odisha 751024, India.
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7
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Abstract
The number of (TTAGGG)n repeats at the ends of chromosomes is highly variable between individual chromosomes, between different cells and between species. Progressive loss of telomere repeats limits the proliferation of pre-malignant human cells but also contributes to aging by inducing apoptosis and senescence in normal cells. Despite enormous progress in understanding distinct pathways that result in loss and gain of telomeric DNA in different cell types, many questions remain. Further studies are needed to delineate the role of damage to telomeric DNA, replication errors, chromatin structure, liquid-liquid phase transition, telomeric transcripts (TERRA) and secondary DNA structures such as guanine quadruplex structures, R-loops and T-loops in inducing gains and losses of telomere repeats in different cell types. Limitations of current telomere length measurements techniques and differences in telomere biology between species and different cell types complicate generalizations about the role of telomeres in aging and cancer. Here some of the factors regulating the telomere length in embryonic and adult cells in mammals are discussed from a mechanistic and evolutionary perspective.
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Affiliation(s)
- Peter Lansdorp
- Terry Fox Laboratory, British Columbia (BC) Cancer Agency, Vancouver, BC, Canada
- Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada
- *Correspondence: Peter Lansdorp,
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8
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Brenner KA, Nandakumar J. Consequences of telomere replication failure: the other end-replication problem. Trends Biochem Sci 2022; 47:506-517. [PMID: 35440402 PMCID: PMC9106919 DOI: 10.1016/j.tibs.2022.03.013] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Revised: 02/28/2022] [Accepted: 03/17/2022] [Indexed: 01/14/2023]
Abstract
Telomeres are chromosome-capping structures that protect ends of the linear genome from DNA damage sensors. However, these structures present obstacles during DNA replication. Incomplete telomere replication accelerates telomere shortening and limits replicative lifespan. Therefore, continued proliferation under conditions of replication stress requires a means of telomere repair, particularly in the absence of telomerase. It was recently revealed that replication stress triggers break-induced replication (BIR) and mitotic DNA synthesis (MiDAS) at mammalian telomeres; however, these mechanisms are error prone and primarily utilized in tumorigenic contexts. In this review article, we discuss the consequences of replication stress at telomeres and how use of available repair pathways contributes to genomic instability. Current research suggests that fragile telomeres are ultimately tumor-suppressive and thus may be better left unrepaired.
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Affiliation(s)
- Kirsten A Brenner
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA.
| | - Jayakrishnan Nandakumar
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA.
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9
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Enhanced radiosensitivity by 6-thio-dG via increasing telomere dysfunction and ataxia telangiectasia mutated inhibition in non-small cell lung cancer. RADIATION MEDICINE AND PROTECTION 2022. [DOI: 10.1016/j.radmp.2022.04.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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10
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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: 14] [Impact Index Per Article: 7.0] [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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Higa M, Matsuda Y, Fujii J, Sugimoto N, Yoshida K, Fujita M. TRF2-mediated ORC recruitment underlies telomere stability upon DNA replication stress. Nucleic Acids Res 2021; 49:12234-12251. [PMID: 34761263 PMCID: PMC8643664 DOI: 10.1093/nar/gkab1004] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2021] [Revised: 10/07/2021] [Accepted: 10/12/2021] [Indexed: 12/12/2022] Open
Abstract
Telomeres are intrinsically difficult-to-replicate region of eukaryotic chromosomes. Telomeric repeat binding factor 2 (TRF2) binds to origin recognition complex (ORC) to facilitate the loading of ORC and the replicative helicase MCM complex onto DNA at telomeres. However, the biological significance of the TRF2–ORC interaction for telomere maintenance remains largely elusive. Here, we employed a TRF2 mutant with mutations in two acidic acid residues (E111A and E112A) that inhibited the TRF2–ORC interaction in human cells. The TRF2 mutant was impaired in ORC recruitment to telomeres and showed increased replication stress-associated telomeric DNA damage and telomere instability. Furthermore, overexpression of an ORC1 fragment (amino acids 244–511), which competitively inhibited the TRF2–ORC interaction, increased telomeric DNA damage under replication stress conditions. Taken together, these findings suggest that TRF2-mediated ORC recruitment contributes to the suppression of telomere instability.
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Affiliation(s)
- Mitsunori Higa
- Department of Cellular Biochemistry, Graduate School of Pharmaceutical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Yukihiro Matsuda
- Department of Cellular Biochemistry, Graduate School of Pharmaceutical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Jumpei Fujii
- Department of Cellular Biochemistry, Graduate School of Pharmaceutical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Nozomi Sugimoto
- Department of Cellular Biochemistry, Graduate School of Pharmaceutical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Kazumasa Yoshida
- Department of Cellular Biochemistry, Graduate School of Pharmaceutical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Masatoshi Fujita
- Department of Cellular Biochemistry, Graduate School of Pharmaceutical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
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12
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Translesion polymerase eta both facilitates DNA replication and promotes increased human genetic variation at common fragile sites. Proc Natl Acad Sci U S A 2021; 118:2106477118. [PMID: 34815340 PMCID: PMC8640788 DOI: 10.1073/pnas.2106477118] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/08/2021] [Indexed: 01/23/2023] Open
Abstract
Common fragile sites (CFSs) are difficult-to-replicate genomic regions that form gaps and breaks on metaphase chromosomes under replication stress. They are hotspots for chromosomal instability in cancer. Repetitive sequences located at CFS loci are inefficiently copied by replicative DNA polymerase (Pol) delta. However, translesion synthesis Pol eta has been shown to efficiently polymerize CFS-associated repetitive sequences in vitro and facilitate CFS stability by a mechanism that is not fully understood. Here, by locus-specific, single-molecule replication analysis, we identified a crucial role for Pol eta (encoded by the gene POLH) in the in vivo replication of CFSs, even without exogenous stress. We find that Pol eta deficiency induces replication pausing, increases initiation events, and alters the direction of replication-fork progression at CFS-FRA16D in both lymphoblasts and fibroblasts. Furthermore, certain replication pause sites at CFS-FRA16D were associated with the presence of non-B DNA-forming motifs, implying that non-B DNA structures could increase replication hindrance in the absence of Pol eta. Further, in Pol eta-deficient fibroblasts, there was an increase in fork pausing at fibroblast-specific CFSs. Importantly, while not all pause sites were associated with non-B DNA structures, they were embedded within regions of increased genetic variation in the healthy human population, with mutational spectra consistent with Pol eta activity. From these findings, we propose that Pol eta replicating through CFSs may result in genetic variations found in the human population at these sites.
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13
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Lin CYG, Näger AC, Lunardi T, Vančevska A, Lossaint G, Lingner J. The human telomeric proteome during telomere replication. Nucleic Acids Res 2021; 49:12119-12135. [PMID: 34747482 PMCID: PMC8643687 DOI: 10.1093/nar/gkab1015] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Revised: 10/07/2021] [Accepted: 10/13/2021] [Indexed: 11/13/2022] Open
Abstract
Telomere shortening can cause detrimental diseases and contribute to aging. It occurs due to the end replication problem in cells lacking telomerase. Furthermore, recent studies revealed that telomere shortening can be attributed to difficulties of the semi-conservative DNA replication machinery to replicate the bulk of telomeric DNA repeats. To investigate telomere replication in a comprehensive manner, we develop QTIP-iPOND - Quantitative Telomeric chromatin Isolation Protocol followed by isolation of Proteins On Nascent DNA - which enables purification of proteins that associate with telomeres specifically during replication. In addition to the core replisome, we identify a large number of proteins that specifically associate with telomere replication forks. Depletion of several of these proteins induces telomere fragility validating their importance for telomere replication. We also find that at telomere replication forks the single strand telomere binding protein POT1 is depleted, whereas histone H1 is enriched. Our work reveals the dynamic changes of the telomeric proteome during replication, providing a valuable resource of telomere replication proteins. To our knowledge, this is the first study that examines the replisome at a specific region of the genome.
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Affiliation(s)
- Chih-Yi Gabriela Lin
- Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Anna Christina Näger
- Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Thomas Lunardi
- Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Aleksandra Vančevska
- Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Gérald Lossaint
- Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Joachim Lingner
- Swiss Institute for Experimental Cancer Research (ISREC), School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
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14
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Glousker G, Lingner J. Challenging endings: How telomeres prevent fragility. Bioessays 2021; 43:e2100157. [PMID: 34436787 DOI: 10.1002/bies.202100157] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Revised: 08/10/2021] [Accepted: 08/11/2021] [Indexed: 12/23/2022]
Abstract
It has become apparent that difficulties to replicate telomeres concern not only the very ends of eukaryotic chromosomes. The challenges already start when the replication fork enters the telomeric repeats. The obstacles encountered consist mainly of noncanonical nucleic acid structures that interfere with replication if not resolved. Replication stress at telomeres promotes the formation of so-called fragile telomeres displaying an abnormal appearance in metaphase chromosomes though their exact molecular nature remains to be elucidated. A substantial number of factors is required to counteract fragility. In this review we promote the hypothesis that telomere fragility is not caused directly by an initial insult during replication but it results as a secondary consequence of DNA repair of damaged replication forks by the homologous DNA recombination machinery. Incomplete DNA synthesis at repair sites or partial chromatin condensation may become apparent as telomere fragility. Fragility and DNA repair during telomere replication emerges as a common phenomenon which exacerbates in multiple disease conditions.
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Affiliation(s)
- Galina Glousker
- School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), Swiss Institute for Experimental Cancer Research (ISREC), Lausanne, Switzerland
| | - Joachim Lingner
- School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), Swiss Institute for Experimental Cancer Research (ISREC), Lausanne, Switzerland
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15
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Multifunctionality of the Telomere-Capping Shelterin Complex Explained by Variations in Its Protein Composition. Cells 2021; 10:cells10071753. [PMID: 34359923 PMCID: PMC8305809 DOI: 10.3390/cells10071753] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Revised: 07/03/2021] [Accepted: 07/09/2021] [Indexed: 12/31/2022] Open
Abstract
Protecting telomere from the DNA damage response is essential to avoid the entry into cellular senescence and organismal aging. The progressive telomere DNA shortening in dividing somatic cells, programmed during development, leads to critically short telomeres that trigger replicative senescence and thereby contribute to aging. In several organisms, including mammals, telomeres are protected by a protein complex named Shelterin that counteract at various levels the DNA damage response at chromosome ends through the specific function of each of its subunits. The changes in Shelterin structure and function during development and aging is thus an intense area of research. Here, we review our knowledge on the existence of several Shelterin subcomplexes and the functional independence between them. This leads us to discuss the possibility that the multifunctionality of the Shelterin complex is determined by the formation of different subcomplexes whose composition may change during aging.
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Replication initiation: Implications in genome integrity. DNA Repair (Amst) 2021; 103:103131. [PMID: 33992866 DOI: 10.1016/j.dnarep.2021.103131] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2021] [Revised: 05/07/2021] [Accepted: 05/07/2021] [Indexed: 02/01/2023]
Abstract
In every cell cycle, billions of nucleotides need to be duplicated within hours, with extraordinary precision and accuracy. The molecular mechanism by which cells regulate the replication event is very complicated, and the entire process begins way before the onset of S phase. During the G1 phase of the cell cycle, cells prepare by assembling essential replication factors to establish the pre-replicative complex at origins, sites that dictate where replication would initiate during S phase. During S phase, the replication process is tightly coupled with the DNA repair system to ensure the fidelity of replication. Defects in replication and any error must be recognized by DNA damage response and checkpoint signaling pathways in order to halt the cell cycle before cells are allowed to divide. The coordination of these processes throughout the cell cycle is therefore critical to achieve genomic integrity and prevent diseases. In this review, we focus on the current understanding of how the replication initiation events are regulated to achieve genome stability.
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Bonnell E, Pasquier E, Wellinger RJ. Telomere Replication: Solving Multiple End Replication Problems. Front Cell Dev Biol 2021; 9:668171. [PMID: 33869233 PMCID: PMC8047117 DOI: 10.3389/fcell.2021.668171] [Citation(s) in RCA: 48] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Accepted: 03/10/2021] [Indexed: 12/19/2022] Open
Abstract
Eukaryotic genomes are highly complex and divided into linear chromosomes that require end protection from unwarranted fusions, recombination, and degradation in order to maintain genomic stability. This is accomplished through the conserved specialized nucleoprotein structure of telomeres. Due to the repetitive nature of telomeric DNA, and the unusual terminal structure, namely a protruding single stranded 3' DNA end, completing telomeric DNA replication in a timely and efficient manner is a challenge. For example, the end replication problem causes a progressive shortening of telomeric DNA at each round of DNA replication, thus telomeres eventually lose their protective capacity. This phenomenon is counteracted by the recruitment and the activation at telomeres of the specialized reverse transcriptase telomerase. Despite the importance of telomerase in providing a mechanism for complete replication of telomeric ends, the majority of telomere replication is in fact carried out by the conventional DNA replication machinery. There is significant evidence demonstrating that progression of replication forks is hampered at chromosomal ends due to telomeric sequences prone to form secondary structures, tightly DNA-bound proteins, and the heterochromatic nature of telomeres. The telomeric loop (t-loop) formed by invasion of the 3'-end into telomeric duplex sequences may also impede the passage of replication fork. Replication fork stalling can lead to fork collapse and DNA breaks, a major cause of genomic instability triggered notably by unwanted repair events. Moreover, at chromosomal ends, unreplicated DNA distal to a stalled fork cannot be rescued by a fork coming from the opposite direction. This highlights the importance of the multiple mechanisms involved in overcoming fork progression obstacles at telomeres. Consequently, numerous factors participate in efficient telomeric DNA duplication by preventing replication fork stalling or promoting the restart of a stalled replication fork at telomeres. In this review, we will discuss difficulties associated with the passage of the replication fork through telomeres in both fission and budding yeasts as well as mammals, highlighting conserved mechanisms implicated in maintaining telomere integrity during replication, thus preserving a stable genome.
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Affiliation(s)
| | | | - Raymund J. Wellinger
- Department of Microbiology and Infectious Diseases, Faculty of Medicine and Health Sciences, Cancer Research Pavilion, Université de Sherbrooke, Sherbrooke, QC, Canada
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Bauwens S, Lototska L, Koundrioukoff S, Debatisse M, Ye J, Gilson E, Mendez-Bermudez A. The Telomeric Protein TRF2 Regulates Replication Origin Activity within Pericentromeric Heterochromatin. Life (Basel) 2021; 11:life11040267. [PMID: 33804994 PMCID: PMC8063955 DOI: 10.3390/life11040267] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Revised: 02/12/2021] [Accepted: 03/22/2021] [Indexed: 12/12/2022] Open
Abstract
Heterochromatic regions render the replication process particularly difficult due to the high level of chromatin compaction and the presence of repeated DNA sequences. In humans, replication through pericentromeric heterochromatin requires the binding of a complex formed by the telomeric factor TRF2 and the helicase RTEL1 in order to relieve topological barriers blocking fork progression. Since TRF2 is known to bind the Origin Replication Complex (ORC), we hypothesized that this factor could also play a role at the replication origins (ORI) of these heterochromatin regions. By performing DNA combing analysis, we found that the ORI density is higher within pericentromeric satellite DNA repeats than within bulk genomic DNA and decreased upon TRF2 downregulation. Moreover, we showed that TRF2 and ORC2 interact in pericentromeric DNA, providing a mechanism by which TRF2 is involved in ORI activity. Altogether, our findings reveal an essential role for TRF2 in pericentromeric heterochromatin replication by regulating both replication initiation and elongation.
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Affiliation(s)
- Serge Bauwens
- Faculty of Medicine Nice, Institute for Research on Cancer and Aging (IRCAN), CNRS, INSERM, Université Côte d’Azur, 06107 Nice, France; (S.B.); (L.L.)
| | - Liudmyla Lototska
- Faculty of Medicine Nice, Institute for Research on Cancer and Aging (IRCAN), CNRS, INSERM, Université Côte d’Azur, 06107 Nice, France; (S.B.); (L.L.)
| | - Stephane Koundrioukoff
- Institut Gustave Roussy, Sorbonne Université, UPMC University, 94805 Villejuif, France; (S.K.); (M.D.)
| | - Michelle Debatisse
- Institut Gustave Roussy, Sorbonne Université, UPMC University, 94805 Villejuif, France; (S.K.); (M.D.)
| | - Jing Ye
- International Laboratory in Hematology, Cancer and Aging, Pôle Sino-Français de Recherches en Sciences du Vivant et Génomique, Rui Jin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China;
| | - Eric Gilson
- Faculty of Medicine Nice, Institute for Research on Cancer and Aging (IRCAN), CNRS, INSERM, Université Côte d’Azur, 06107 Nice, France; (S.B.); (L.L.)
- International Laboratory in Hematology, Cancer and Aging, Pôle Sino-Français de Recherches en Sciences du Vivant et Génomique, Rui Jin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China;
- Correspondence: (E.G.); (A.M.-B.)
| | - Aaron Mendez-Bermudez
- Faculty of Medicine Nice, Institute for Research on Cancer and Aging (IRCAN), CNRS, INSERM, Université Côte d’Azur, 06107 Nice, France; (S.B.); (L.L.)
- International Laboratory in Hematology, Cancer and Aging, Pôle Sino-Français de Recherches en Sciences du Vivant et Génomique, Rui Jin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China;
- Correspondence: (E.G.); (A.M.-B.)
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TERRA G-quadruplex RNA interaction with TRF2 GAR domain is required for telomere integrity. Sci Rep 2021; 11:3509. [PMID: 33568696 PMCID: PMC7876106 DOI: 10.1038/s41598-021-82406-x] [Citation(s) in RCA: 44] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2020] [Accepted: 01/13/2021] [Indexed: 12/15/2022] Open
Abstract
Telomere dysfunction causes chromosomal instability which is associated with many cancers and age-related diseases. The non-coding telomeric repeat-containing RNA (TERRA) forms a structural and regulatory component of the telomere that is implicated in telomere maintenance and chromosomal end protection. The basic N-terminal Gly/Arg-rich (GAR) domain of telomeric repeat-binding factor 2 (TRF2) can bind TERRA but the structural basis and significance of this interaction remains poorly understood. Here, we show that TRF2 GAR recognizes G-quadruplex features of TERRA. We show that small molecules that disrupt the TERRA-TRF2 GAR complex, such as N-methyl mesoporphyrin IX (NMM) or genetic deletion of TRF2 GAR domain, result in the loss of TERRA, and the induction of γH2AX-associated telomeric DNA damage associated with decreased telomere length, and increased telomere aberrations, including telomere fragility. Taken together, our data indicates that the G-quadruplex structure of TERRA is an important recognition element for TRF2 GAR domain and this interaction between TRF2 GAR and TERRA is essential to maintain telomere stability.
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On K, Crevel G, Cotterill S, Itoh M, Kato Y. Drosophila telomere capping protein HOAP interacts with DSB sensor proteins Mre11 and Nbs. Genes Cells 2021; 26:219-229. [PMID: 33556205 DOI: 10.1111/gtc.12836] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2020] [Revised: 01/15/2021] [Accepted: 02/01/2021] [Indexed: 12/12/2022]
Abstract
In eukaryotes, specific DNA-protein structures called telomeres exist at linear chromosome ends. Telomere stability is maintained by a specific capping protein complex. This capping complex is essential for the inhibition of the DNA damage response (DDR) at telomeres and contributes to genome integrity. In Drosophila, the central factors of telomere capping complex are HOAP and HipHop. Furthermore, a DDR protein complex Mre11-Rad50-Nbs (MRN) is known to be important for the telomere association of HOAP and HipHop. However, whether MRN interacts with HOAP and HipHop, and the telomere recognition mechanisms of HOAP and HipHop are poorly understood. Here, we show that Nbs interacts with Mre11 and transports the Mre11-Rad50 complex from the cytoplasm to the nucleus. In addition, we report that HOAP interacts with both Mre11 and Nbs. The N-terminal region of HOAP is essential for its co-localization with HipHop. Finally, we reveal that Nbs interacts with the N-terminal region of HOAP.
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Affiliation(s)
- Kinyo On
- Department of Applied Biology, Kyoto Institute of Technology, Kyoto, Japan
| | - Gilles Crevel
- Department of Basic Medical Sciences, St Georges, University of London, London, UK
| | - Sue Cotterill
- Department of Basic Medical Sciences, St Georges, University of London, London, UK
| | - Masanobu Itoh
- Department of Applied Biology, Kyoto Institute of Technology, Kyoto, Japan.,Advanced Insect Research Promotion Center, Kyoto Institute of Technology, Kyoto, Japan
| | - Yasuko Kato
- Department of Applied Biology, Kyoto Institute of Technology, Kyoto, Japan.,Advanced Insect Research Promotion Center, Kyoto Institute of Technology, Kyoto, Japan
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