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Bailey SM, Kunkel SR, Bedford JS, Cornforth MN. The Central Role of Cytogenetics in Radiation Biology. Radiat Res 2024; 202:227-259. [PMID: 38981612 DOI: 10.1667/rade-24-00038.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2024] [Accepted: 04/23/2024] [Indexed: 07/11/2024]
Abstract
Radiation cytogenetics has a rich history seldom appreciated by those outside the field. Early radiobiology was dominated by physics and biophysical concepts that borrowed heavily from the study of radiation-induced chromosome aberrations. From such studies, quantitative relationships between biological effect and changes in absorbed dose, dose rate and ionization density were codified into key concepts of radiobiological theory that have persisted for nearly a century. This review aims to provide a historical perspective of some of these concepts, including evidence supporting the contention that chromosome aberrations underlie development of many, if not most, of the biological effects of concern for humans exposed to ionizing radiations including cancer induction, on the one hand, and tumor eradication on the other. The significance of discoveries originating from these studies has widened and extended far beyond their original scope. Chromosome structural rearrangements viewed in mitotic cells were first attributed to the production of breaks by the radiations during interphase, followed by the rejoining or mis-rejoining among ends of other nearby breaks. These relatively modest beginnings eventually led to the discovery and characterization of DNA repair of double-strand breaks by non-homologous end joining, whose importance to various biological processes is now widely appreciated. Two examples, among many, are V(D)J recombination and speciation. Rapid technological advancements in cytogenetics, the burgeoning fields of molecular radiobiology and third-generation sequencing served as a point of confluence between the old and new. As a result, the emergent field of "cytogenomics" now becomes uniquely positioned for the purpose of more fully understanding mechanisms underlying the biological effects of ionizing radiation exposure.
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Affiliation(s)
- Susan M Bailey
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, Colorado
| | - Stephen R Kunkel
- Department of Radiation Oncology, University of Texas Medical Branch, Galveston, Texas
| | - Joel S Bedford
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, Colorado
| | - Michael N Cornforth
- Department of Radiation Oncology, University of Texas Medical Branch, Galveston, Texas
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2
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Rødland GE, Temelie M, Eek Mariampillai A, Hauge S, Gilbert A, Chevalier F, Savu DI, Syljuåsen RG. Potential Benefits of Combining Proton or Carbon Ion Therapy with DNA Damage Repair Inhibitors. Cells 2024; 13:1058. [PMID: 38920686 PMCID: PMC11201490 DOI: 10.3390/cells13121058] [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: 04/29/2024] [Revised: 06/03/2024] [Accepted: 06/05/2024] [Indexed: 06/27/2024] Open
Abstract
The use of charged particle radiotherapy is currently increasing, but combination therapy with DNA repair inhibitors remains to be exploited in the clinic. The high-linear energy transfer (LET) radiation delivered by charged particles causes clustered DNA damage, which is particularly effective in destroying cancer cells. Whether the DNA damage response to this type of damage is different from that elicited in response to low-LET radiation, and if and how it can be targeted to increase treatment efficacy, is not fully understood. Although several preclinical studies have reported radiosensitizing effects when proton or carbon ion irradiation is combined with inhibitors of, e.g., PARP, ATR, ATM, or DNA-PKcs, further exploration is required to determine the most effective treatments. Here, we examine what is known about repair pathway choice in response to high- versus low-LET irradiation, and we discuss the effects of inhibitors of these pathways when combined with protons and carbon ions. Additionally, we explore the potential effects of DNA repair inhibitors on antitumor immune signaling upon proton and carbon ion irradiation. Due to the reduced effect on healthy tissue and better immune preservation, particle therapy may be particularly well suited for combination with DNA repair inhibitors.
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Affiliation(s)
- Gro Elise Rødland
- Department of Radiation Biology, Institute for Cancer Research, Norwegian Radium Hospital, Oslo University Hospital, 0379 Oslo, Norway
| | - Mihaela Temelie
- Department of Life and Environmental Physics, Horia Hulubei National Institute of Physics and Nuclear Engineering, 077125 Magurele, Romania
| | - Adrian Eek Mariampillai
- Department of Radiation Biology, Institute for Cancer Research, Norwegian Radium Hospital, Oslo University Hospital, 0379 Oslo, Norway
| | - Sissel Hauge
- Department of Radiation Biology, Institute for Cancer Research, Norwegian Radium Hospital, Oslo University Hospital, 0379 Oslo, Norway
| | - Antoine Gilbert
- UMR6252 CIMAP, Team Applications in Radiobiology with Accelerated Ions, CEA-CNRS-ENSICAEN-Université de Caen Normandie, 14000 Caen, France (F.C.)
| | - François Chevalier
- UMR6252 CIMAP, Team Applications in Radiobiology with Accelerated Ions, CEA-CNRS-ENSICAEN-Université de Caen Normandie, 14000 Caen, France (F.C.)
| | - Diana I. Savu
- Department of Life and Environmental Physics, Horia Hulubei National Institute of Physics and Nuclear Engineering, 077125 Magurele, Romania
| | - Randi G. Syljuåsen
- Department of Radiation Biology, Institute for Cancer Research, Norwegian Radium Hospital, Oslo University Hospital, 0379 Oslo, Norway
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3
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Ng YB, Akincilar SC. Shaping DNA damage responses: Therapeutic potential of targeting telomeric proteins and DNA repair factors in cancer. Curr Opin Pharmacol 2024; 76:102460. [PMID: 38776747 DOI: 10.1016/j.coph.2024.102460] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2022] [Revised: 10/06/2023] [Accepted: 10/11/2023] [Indexed: 05/25/2024]
Abstract
Shelterin proteins regulate genomic stability by preventing inappropriate DNA damage responses (DDRs) at telomeres. Unprotected telomeres lead to persistent DDR causing cell cycle inhibition, growth arrest, and apoptosis. Cancer cells rely on DDR to protect themselves from DNA lesions and exogenous DNA-damaging agents such as chemotherapy and radiotherapy. Therefore, targeting DDR machinery is a promising strategy to increase the sensitivity of cancer cells to existing cancer therapies. However, the success of these DDR inhibitors depends on other mutations, and over time, patients develop resistance to these therapies. This suggests the need for alternative approaches. One promising strategy is co-inhibiting shelterin proteins with DDR molecules, which would offset cellular fitness in DNA repair in a mutation-independent manner. This review highlights the associations and dependencies of the shelterin complex with the DDR proteins and discusses potential co-inhibition strategies that might improve the therapeutic potential of current inhibitors.
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Affiliation(s)
- Yu Bin Ng
- Laboratory of NFκB Signalling, Institute of Molecular and Cell Biology (IMCB), Agency for Science, Technology and Research (A∗STAR), 61 Biopolis Drive, Proteos, Singapore 138673, Republic of Singapore
| | - Semih Can Akincilar
- Laboratory of NFκB Signalling, Institute of Molecular and Cell Biology (IMCB), Agency for Science, Technology and Research (A∗STAR), 61 Biopolis Drive, Proteos, Singapore 138673, Republic of Singapore.
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4
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Sonmez C, Toia B, Eickhoff P, Matei AM, El Beyrouthy M, Wallner B, Douglas ME, de Lange T, Lottersberger F. DNA-PK controls Apollo's access to leading-end telomeres. Nucleic Acids Res 2024; 52:4313-4327. [PMID: 38407308 PMCID: PMC11077071 DOI: 10.1093/nar/gkae105] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2023] [Revised: 01/23/2024] [Accepted: 02/01/2024] [Indexed: 02/27/2024] Open
Abstract
The complex formed by Ku70/80 and DNA-PKcs (DNA-PK) promotes the synapsis and the joining of double strand breaks (DSBs) during canonical non-homologous end joining (c-NHEJ). In c-NHEJ during V(D)J recombination, DNA-PK promotes the processing of the ends and the opening of the DNA hairpins by recruiting and/or activating the nuclease Artemis/DCLRE1C/SNM1C. Paradoxically, DNA-PK is also required to prevent the fusions of newly replicated leading-end telomeres. Here, we describe the role for DNA-PK in controlling Apollo/DCLRE1B/SNM1B, the nuclease that resects leading-end telomeres. We show that the telomeric function of Apollo requires DNA-PKcs's kinase activity and the binding of Apollo to DNA-PK. Furthermore, AlphaFold-Multimer predicts that Apollo's nuclease domain has extensive additional interactions with DNA-PKcs, and comparison to the cryo-EM structure of Artemis bound to DNA-PK phosphorylated on the ABCDE/Thr2609 cluster suggests that DNA-PK can similarly grant Apollo access to the DNA end. In agreement, the telomeric function of DNA-PK requires the ABCDE/Thr2609 cluster. These data reveal that resection of leading-end telomeres is regulated by DNA-PK through its binding to Apollo and its (auto)phosphorylation-dependent positioning of Apollo at the DNA end, analogous but not identical to DNA-PK dependent regulation of Artemis at hairpins.
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Affiliation(s)
- Ceylan Sonmez
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping 58 183, Sweden
| | - Beatrice Toia
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping 58 183, Sweden
| | - Patrik Eickhoff
- Chester Beatty Laboratories, The Institute of Cancer Research, 237 Fulham Road, London SW3 6JB, UK
| | - Andreea Medeea Matei
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping 58 183, Sweden
| | - Michael El Beyrouthy
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping 58 183, Sweden
| | - Björn Wallner
- Department of Physics, Chemistry and Biology, Linköping University, Linköping 58 183, Sweden
| | - Max E Douglas
- Chester Beatty Laboratories, The Institute of Cancer Research, 237 Fulham Road, London SW3 6JB, UK
| | - Titia de Lange
- Laboratory for Cell Biology and Genetics, The Rockefeller University, 1230 York Avenue, NY, NY 10021, USA
| | - Francisca Lottersberger
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping 58 183, Sweden
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Milletti G, Colicchia V, Cecconi F. Cyclers' kinases in cell division: from molecules to cancer therapy. Cell Death Differ 2023; 30:2035-2052. [PMID: 37516809 PMCID: PMC10482880 DOI: 10.1038/s41418-023-01196-z] [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: 04/27/2023] [Revised: 07/08/2023] [Accepted: 07/18/2023] [Indexed: 07/31/2023] Open
Abstract
Faithful eucaryotic cell division requires spatio-temporal orchestration of multiple sequential events. To ensure the dynamic nature of these molecular and morphological transitions, a swift modulation of key regulatory pathways is necessary. The molecular process that most certainly fits this description is phosphorylation, the post-translational modification provided by kinases, that is crucial to allowing the progression of the cell cycle and that culminates with the separation of two identical daughter cells. In detail, from the early stages of the interphase to the cytokinesis, each critical step of this process is tightly regulated by multiple families of kinases including the Cyclin-dependent kinases (CDKs), kinases of the Aurora, Polo, Wee1 families, and many others. While cell-cycle-related CDKs control the timing of the different phases, preventing replication machinery errors, the latter modulate the centrosome cycle and the spindle function, avoiding karyotypic abnormalities typical of chromosome instability. Such chromosomal abnormalities may result from replication stress (RS) and chromosome mis-segregation and are considered a hallmark of poor prognosis, therapeutic resistance, and metastasis in cancer patients. Here, we discuss recent advances in the understanding of how different families of kinases concur to govern cell cycle, preventing RS and mitotic infidelity. Additionally, considering the growing number of clinical trials targeting these molecules, we review to what extent and in which tumor context cell-cycle-related kinases inhibitors are worth exploiting as an effective therapeutic strategy.
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Affiliation(s)
- Giacomo Milletti
- DNA Replication and Cancer Group, Danish Cancer Institute, 2100, Copenhagen, Denmark.
- Department of Pediatric Hematology and Oncology and of Cell and Gene Therapy, IRCCS Ospedale Pediatrico Bambino Gesù, Rome, Italy.
| | - Valeria Colicchia
- Department of Biology, University of Rome Tor Vergata, Rome, Italy
- IRBM S.p.A., Via Pontina Km 30.60, 00070, Pomezia, Italy
| | - Francesco Cecconi
- Cell Stress and Survival Group, Center for Autophagy, Recycling and Disease (CARD), Danish Cancer Institute, Copenhagen, Denmark.
- Università Cattolica del Sacro Cuore and Fondazione Policlinico Universitario Agostino Gemelli IRCCS, Rome, Italy.
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6
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Dutta B, Osato M. The RUNX Family, a Novel Multifaceted Guardian of the Genome. Cells 2023; 12:255. [PMID: 36672189 PMCID: PMC9856552 DOI: 10.3390/cells12020255] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2022] [Revised: 12/24/2022] [Accepted: 12/30/2022] [Indexed: 01/11/2023] Open
Abstract
The DNA repair machinery exists to protect cells from daily genetic insults by orchestrating multiple intrinsic and extrinsic factors. One such factor recently identified is the Runt-related transcription factor (RUNX) family, a group of proteins that act as a master transcriptional regulator for multiple biological functions such as embryonic development, stem cell behaviors, and oncogenesis. A significant number of studies in the past decades have delineated the involvement of RUNX proteins in DNA repair. Alterations in RUNX genes cause organ failure and predisposition to cancers, as seen in patients carrying mutations in the other well-established DNA repair genes. Herein, we review the currently existing findings and provide new insights into transcriptional and non-transcriptional multifaceted regulation of DNA repair by RUNX family proteins.
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Affiliation(s)
- Bibek Dutta
- Department of Paediatrics, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117599, Singapore
- Cancer Science Institute of Singapore, National University of Singapore, Singapore 117599, Singapore
| | - Motomi Osato
- Department of Paediatrics, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117599, Singapore
- Cancer Science Institute of Singapore, National University of Singapore, Singapore 117599, Singapore
- International Research Center for Medical Sciences, Kumamoto University, Kumamoto 860-0811, Japan
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Low GKM, Ting APL, Fok EDZ, Gopalakrishnan K, Zeegers D, Khaw AK, Jayapal M, Martinez-Lopez W, Hande MP. Role of Xeroderma pigmentosum D (XPD) protein in genome maintenance in human cells under oxidative stress. MUTATION RESEARCH. GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2022; 876-877:503444. [PMID: 35483790 DOI: 10.1016/j.mrgentox.2022.503444] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Revised: 12/29/2021] [Accepted: 01/10/2022] [Indexed: 06/14/2023]
Abstract
Xeroderma pigmentosum D (XPD) protein plays a pivotal role in the nucleotide excision repair pathway. XPD unwinds the local area of the damaged DNA by virtue of constituting transcription factor II H (TFIIH) and is important not only for repair but also for basal transcription. Although cells deficient in XPD have shown to be defective in oxidative base-lesion repair, the effects of the oxidative assault on primary fibroblasts from patients suffering from Xeroderma Pigmentosum D have not been fully explored. Therefore, we sought to investigate the role of XPD in oxidative DNA damage-repair by treating primary fibroblasts derived from a patient suffering from Xeroderma Pigmentosum D, with hydrogen peroxide. Our results show dose-dependent increase in genotoxicity with minimal effect on cytotoxicity with H2O2 in XPD deficient cells compared to control cells. XPD deficient cells displayed increased susceptibility and reduced repair capacity when subjected to DNA damage induced by oxidative stress. XPD deficient fibroblasts exhibited increased telomeric loss after H2O2 treatment. In addition, we demonstrated that chronic oxidative stress induced accelerated premature senescence characteristics. Gene expression profiling revealed alterations in genes involved in transcription and nucleotide metabolisms, as well as in cellular and cell cycle processes in a more significant way than in other pathways. This study highlights the role of XPD in the repair of oxidative stress and telomere maintenance. Lack of functional XPD seems to increase the susceptibility of oxidative stress-induced genotoxicity while retaining cell viability posing as a potential cancer risk factor of Xeroderma Pigmentosum D patients.
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Affiliation(s)
- Grace Kah Mun Low
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Aloysius Poh Leong Ting
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Edwin Dan Zhihao Fok
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Kalpana Gopalakrishnan
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Dimphy Zeegers
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Aik Kia Khaw
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Manikandan Jayapal
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Wilner Martinez-Lopez
- Instituto de Investigaciones Biológicas Clemente Estable, Montevideo, Uruguay; Associate Unit on Genomic Stability, Faculty of Medicine, University of the Republic (UdelaR), Montevideo, Uruguay; Vellore Institute of Technology, Vellore, India
| | - M Prakash Hande
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore; Vellore Institute of Technology, Vellore, India; Mangalore University, India.
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8
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Lu YJ, Yang Y, Hu TH, Duan WM. Identification of key genes and pathways at the downstream of S100PBP in pancreatic cancer cells by integrated bioinformatical analysis. Transl Cancer Res 2022; 10:806-816. [PMID: 35116411 PMCID: PMC8799081 DOI: 10.21037/tcr-20-2531] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Accepted: 12/11/2020] [Indexed: 12/12/2022]
Abstract
Background The aim of the present study was to identify key genes and pathways downstream of S100PPBP in pancreatic cancer cells. Methods The microarray datasets GSE35196 (S100PBP knockdown) and GSE35198 (S100PBP overexpression) were downloaded from the Gene Expression Omnibus (GEO). Differentially expressed genes (DEGs) were obtained separately from GEO2R, and heatmaps showing clustering analysis of DEGs were generated using R software. Gene Ontology and pathway enrichment analyses were performed for identified DEGs using the Database for Annotation, Visualization, and Integrated Discovery and Kyoto Encyclopedia of Genes and Genomes, respectively. A protein-protein interaction (PPI) network was created using the Search Tool for the Retrieval of Interacting Genes and Cytoscape software. Relevant expression datasets of key identified genes were downloaded from The Cancer Genome Atlas, and overall survival (OS) analysis was performed with R software. Finally, Gene Expression Profiling Interactive Analysis was used to evaluate the expression of key DEGs in pancreatic cancer tissues. Results A total of 34 DEGs (11 upregulated and 23 downregulated) were screened out from the two datasets. Gene Ontology enrichment analysis revealed that the identified DEGs were mainly functionally enriched in ATPase activity, production of siRNA involved in RNA interference, and production of miRNAs involved in gene silencing by miRNA. The pathway enrichment analysis of the identified DEGs showed enrichment mainly in apoptosis, non-homologous end-joining, and miRNA pathways in cancer. The protein–protein interaction network was composed of 21 nodes and 30 edges. After survival analysis and gene expression analysis, 4 genes associated with poor prognosis were selected, including LMNB1, PRKRA, SEPT2, and XRCC5. Conclusions LMNB1, PRKRA, SEPT2, and XRCC5 could be key downstream genes of the S100PBP gene in the inhibition of pancreatic cancer cell adhesion.
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Affiliation(s)
- Yu-Jie Lu
- Department of Oncology, the First Affiliated Hospital of Soochow University, Suzhou, China
| | - Yi Yang
- Department of Gastroenterology, the First Affiliated Hospital of Soochow University, Suzhou, China
| | - Ting-Hui Hu
- Department of General Surgery, the First Affiliated Hospital of Soochow University, Suzhou, China
| | - Wei-Ming Duan
- Department of Oncology, the First Affiliated Hospital of Soochow University, Suzhou, China
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Abstract
In this perspective, we introduce shelterin and the mechanisms of ATM activation and NHEJ at telomeres, before discussing the following questions: How are t-loops proposed to protect chromosome ends and what is the evidence for this model? Can other models explain how TRF2 mediates end protection? Could t-loops be pathological structures? How is end protection achieved in pluripotent cells? What do the insights into telomere end protection in pluripotent cells mean for the t-loop model of end protection? Why might different cell states have evolved different mechanisms of end protection? Finally, we offer support for an updated t-loop model of end protection, suggesting that the data is supportive of a critical role for t-loops in protecting chromosome ends from NHEJ and ATM activation, but that other mechanisms are involved. Finally, we propose that t-loops are likely dynamic, rather than static, structures.
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Affiliation(s)
- Phil Ruis
- The Francis Crick Institute, London NW1 1AT, United Kingdom
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10
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Sui J, Zhang S, Chen BPC. DNA-dependent protein kinase in telomere maintenance and protection. Cell Mol Biol Lett 2020; 25:2. [PMID: 31988640 PMCID: PMC6969447 DOI: 10.1186/s11658-020-0199-0] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Accepted: 01/02/2020] [Indexed: 12/12/2022] Open
Abstract
This review focuses on DNA-dependent protein kinase (DNA-PK), which is the key regulator of canonical non-homologous end-joining (NHEJ), the predominant mechanism of DNA double-strand break (DSB) repair in mammals. DNA-PK consists of the DNA-binding Ku70/80 heterodimer and the catalytic subunit DNA-PKcs. They assemble at DNA ends, forming the active DNA-PK complex, which initiates NHEJ-mediated DSB repair. Paradoxically, both Ku and DNA-PKcs are associated with telomeres, and they play crucial roles in protecting the telomere against fusions. Herein, we discuss possible mechanisms and contributions of Ku and DNA-PKcs in telomere regulation.
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Affiliation(s)
- Jiangdong Sui
- 1Radiation Oncology Center, Chongqing University Cancer Hospital, Chongqing, 400030 China
| | - Shichuan Zhang
- 2Department of Radiation Oncology, Sichuan Cancer Hospital, Chengdu, China
| | - Benjamin P C Chen
- 3Department of Radiation Oncology, University of Texas Southwestern Medical Center, 2201 Inwood Rd., Dallas, TX 75390-9187 USA
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Zheng JT, Zhang N, Yu YH, Gong PT, Li XH, Wu N, Wang C, Wang XC, Li X, Li JH, Zhang XC. Identification of a TRBD zinc finger-interacting protein in Giardia duodenalis and its regulation of telomerase. Parasit Vectors 2019; 12:568. [PMID: 31783771 PMCID: PMC6884763 DOI: 10.1186/s13071-019-3821-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Accepted: 11/21/2019] [Indexed: 11/10/2022] Open
Abstract
Background Giardia duodenalis causes giardiasis, with diarrhea as the primary symptom. The trophozoite proliferation of this zoonotic parasite is mainly affected by telomerase, although the mechanism of telomerase regulation has not been thoroughly analyzed. Methods This study was performed to identify the telomerase RNA-binding domain (TRBD)-interacting protein in G. duodenalis and its regulation of telomerase. Interaction between TRBD and interacting proteins was verified via pulldown assays and co-immunoprecipitation (co-IP) techniques, and the subcellular localization of the protein interactions was determined in vivo via split SNAP-tag labeling. The hammerhead ribozyme was designed to deplete the mRNA of TRBD-interacting proteins. Results Using TRBD as bait, we identified zinc-finger domain (ZFD)-containing proteins and verified it via pulldown and co-IP experiments. Protein-protein interaction occurred in the nuclei of 293T cells and both nuclei of G. duodenalis. The hammerhead ribozyme depleted ZFD mRNA levels, which reduced the reproduction rate of G. duodenalis, telomerase activity and telomere length. Conclusions Our findings suggest that ZFD may regulate telomere function in G. duodenalis nuclei.
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Affiliation(s)
- Jing-Tong Zheng
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Institute of Zoonosis, Jilin University, Changchun, 130062, China.,Department of Pathogenobiology, College of Basic Medicine, Jilin University, Changchun, 130021, Jilin, China
| | - Nan Zhang
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Institute of Zoonosis, Jilin University, Changchun, 130062, China.,State and Local Joint Engineering Laboratory for Animal Models of Human Diseases, Academy of Translational Medicine, First Hospital, Jilin University, Changchun, 130021, China
| | - Yan-Hui Yu
- Clinical Laboratory of Second Hospital, Jilin University, Changchun, 130021, China
| | - Peng-Tao Gong
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Institute of Zoonosis, Jilin University, Changchun, 130062, China
| | - Xian-He Li
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Institute of Zoonosis, Jilin University, Changchun, 130062, China
| | - Na Wu
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Institute of Zoonosis, Jilin University, Changchun, 130062, China
| | - Can Wang
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Institute of Zoonosis, Jilin University, Changchun, 130062, China
| | - Xiao-Cen Wang
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Institute of Zoonosis, Jilin University, Changchun, 130062, China
| | - Xin Li
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Institute of Zoonosis, Jilin University, Changchun, 130062, China
| | - Jian-Hua Li
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Institute of Zoonosis, Jilin University, Changchun, 130062, China.
| | - Xi-Chen Zhang
- Key Laboratory of Zoonosis Research, Ministry of Education, College of Veterinary Medicine, Institute of Zoonosis, Jilin University, Changchun, 130062, China.
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12
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ATM, DNA-PKcs and ATR: shaping development through the regulation of the DNA damage responses. ACTA ACUST UNITED AC 2019. [DOI: 10.1007/s42764-019-00003-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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13
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Piekna-Przybylska D, Nagumotu K, Reid DM, Maggirwar SB. HIV-1 infection renders brain vascular pericytes susceptible to the extracellular glutamate. J Neurovirol 2018; 25:114-126. [PMID: 30402824 DOI: 10.1007/s13365-018-0693-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Revised: 09/28/2018] [Accepted: 10/25/2018] [Indexed: 12/18/2022]
Abstract
Reduced pericytes' coverage of endothelium in the brain is one of the structural changes leading to breach of the blood-brain barrier during HIV infection. We previously showed in central memory T (TCM) cells that HIV latency increases cellular susceptibility to DNA damage. In this study, we investigated susceptibility of primary brain pericytes infected with HIV-1 to DNA damage in response to glutamate and TNF-α, both known to induce neuronal death during chronic inflammatory conditions. To infect pericytes, we used a single-cycle HIV-1 pseudotyped with VSV-G envelope glycoprotein and maintained the cultures until latency was established. Our data indicate that pericytes silence HIV-1 expression at similar rate compared to primary TCM cells. TNF-α and IL-1β caused partial reactivation of the virus suggesting that progression of disease and neuroinflammation might facilitate virus reactivation from latency. Significant increases in the level of γH2AX, which reflect DNA damage, were observed in infected cultures exposed to TNF-α and glutamate at day 2 post-infection. Glutamate, an excitatory neurologic stimuli, also caused increases in the γH2AX level in latently infected pericytes, whereas PARP and DNA-PK inhibitors caused reductions in cell population suggesting that HIV-1 latency affects repairs of single- and double-strand DNA breaks. For comparison, we also analyzed latently infected astrocytes and determined that DNA damage response in astrocytes is less affected by HIV-1. In conclusion, our results indicate that productive infection and HIV-1 latency in pericytes interfere with DNA damage response, rendering them vulnerable to the agents that are characteristic of chronic neuroinflammatory disease conditions.
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Affiliation(s)
- Dorota Piekna-Przybylska
- Department of Microbiology and Immunology, School of Medicine and Dentistry, University of Rochester, Rochester, NY, 14642, USA.
| | - Kavyasri Nagumotu
- Department of Microbiology and Immunology, School of Medicine and Dentistry, University of Rochester, Rochester, NY, 14642, USA
| | - Danielle M Reid
- Department of Microbiology and Immunology, School of Medicine and Dentistry, University of Rochester, Rochester, NY, 14642, USA
| | - Sanjay B Maggirwar
- Department of Microbiology and Immunology, School of Medicine and Dentistry, University of Rochester, Rochester, NY, 14642, USA
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14
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Piekna-Przybylska D, Maggirwar SB. CD4+ memory T cells infected with latent HIV-1 are susceptible to drugs targeting telomeres. Cell Cycle 2018; 17:2187-2203. [PMID: 30198385 DOI: 10.1080/15384101.2018.1520568] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The population of HIV reservoir in infected person is very small, but extremely long-lived and is a major obstacle for an HIV cure. We previously showed that cells with established HIV latency have deficiencies in DNA damage response (DDR). Here, we investigated ability of HIV-1 to interfere with telomere maintenance, and the effects of targeting telomeres on latently infected cells. Our results show that telomeres are elongated in cultured primary memory CD4 + T cells (TCM) after HIV-1 infection and when virus latency is established. Similarly, much longer telomeres were found in several Jurkat-derived latently infected cell lines, indicating that virus stimulates telomere elongation. Exposing primary CD4+ TCM cells to BRACO19, an agent targeting telomeres, resulted in a higher rate of apoptosis for infected cultures at day 3 post-infection, during HIV-1 latency and for PMA-stimulated cultures with low level of HIV-1 reactivation. Importantly, BRACO19 induced apoptosis in infected cells with potency similar to etoposide and camptothecin, whereas uninfected cells were less affected by BRACO19. We also determined that apoptosis induced by BRACO19 is not caused by telomeres shortening, but is related to formation of gamma-H2AX, implicating DNA damage or uncapping of telomeres, which triggers genome instability. In conclusion, our results indicate that HIV-1 stimulates telomere elongation during latency, suggesting that HIV reservoir has greater capacity for clonal expansion and extended lifespan. Higher rates of apoptosis in response to BRACO19 treatment suggest that HIV reservoirs are more susceptible to targeting telomere maintenance and to inhibitors targeting DDR, which is also involved in stabilizing telomeres.
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Affiliation(s)
- Dorota Piekna-Przybylska
- a Department of Microbiology and Immunology, School of Medicine and Dentistry , University of Rochester , Rochester , NY , USA
| | - Sanjay B Maggirwar
- a Department of Microbiology and Immunology, School of Medicine and Dentistry , University of Rochester , Rochester , NY , USA
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15
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Lee Y, Okayasu R. Strategies to Enhance Radiosensitivity to Heavy Ion Radiation Therapy. Int J Part Ther 2018; 5:114-121. [DOI: 10.14338/ijpt-18-00014.1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Accepted: 06/16/2018] [Indexed: 11/21/2022] Open
Affiliation(s)
- Younghyun Lee
- Center for Radiological Research, Columbia University Medical Center, New York, NY, USA
| | - Ryuichi Okayasu
- Department of Basic Medical Sciences for Radiation Damages, National Institutes for Quantum and Radiological Science and Technology/National Institute of Radiological Sciences, Japan
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16
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Chung JH. The role of DNA-PK in aging and energy metabolism. FEBS J 2018; 285:1959-1972. [PMID: 29453899 DOI: 10.1111/febs.14410] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Revised: 01/15/2018] [Accepted: 02/12/2018] [Indexed: 12/17/2022]
Abstract
DNA-dependent protein kinase (DNA-PK) is a very large holoenzyme comprised of the p470 kDa DNA-PK catalytic subunit (DNA-PKcs ) and the Ku heterodimer consisting of the p86 (Ku 80) and p70 (Ku 70) subunits. It is best known for its nonhomologous end joining (NHEJ) activity, which repairs double-strand DNA (dsDNA) breaks (DSBs). As expected, the absence of DNA-PK activity results in sensitivity to ionizing radiation, which generates DSBs and defect in lymphocyte development, which requires NHEJ of the V(D)J region in the immunoglobulin and T-cell receptor loci. DNA-PK also has been reported to have functions seemingly unrelated to NHEJ. For example, DNA-PK responds to insulin signaling to facilitate the conversion of carbohydrates to fatty acids in the liver. More recent evidence indicates that DNA-PK activity increases with age in skeletal muscle, promoting mitochondrial loss and weight gain. These discoveries suggest that our understanding of DNA-PK is far from complete. As many excellent reviews have already been written about the role of DNA-PK in NHEJ, here we will review the non-NHEJ role of DNA-PK with a focus on its role in aging and energy metabolism.
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Affiliation(s)
- Jay H Chung
- Laboratory of Obesity and Aging Research, Genetics and Developmental Biology Center, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, MD, USA
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17
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DNA damage, metabolism and aging in pro-inflammatory T cells: Rheumatoid arthritis as a model system. Exp Gerontol 2017; 105:118-127. [PMID: 29101015 DOI: 10.1016/j.exger.2017.10.027] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2017] [Revised: 10/26/2017] [Accepted: 10/30/2017] [Indexed: 01/09/2023]
Abstract
The aging process is the major driver of morbidity and mortality, steeply increasing the risk to succumb to cancer, cardiovascular disease, infection and neurodegeneration. Inflammation is a common denominator in age-related pathologies, identifying the immune system as a gatekeeper in aging overall. Among immune cells, T cells are long-lived and exposed to intense replication pressure, making them sensitive to aging-related abnormalities. In successful T cell aging, numbers of naïve cells, repertoire diversity and activation thresholds are preserved as long as possible; in maladaptive T cell aging, protective T cell functions decline and pro-inflammatory effector cells are enriched. Here, we review in the model system of rheumatoid arthritis (RA) how maladaptive T cell aging renders the host susceptible to chronic, tissue-damaging inflammation. In T cells from RA patients, known to be about 20years pre-aged, three interconnected functional domains are altered: DNA damage repair, metabolic activity generating energy and biosynthetic precursor molecules, and shaping of plasma membranes to promote T cell motility. In each of these domains, key molecules and pathways have now been identified, including the glycolytic enzymes PFKFB3 and G6PD; the DNA repair molecules ATM, DNA-PKcs and MRE11A; and the podosome marker protein TKS5. Some of these molecules may help in defining targetable pathways to slow the T cell aging process.
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18
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DNA-dependent protein kinase modulates the anti-cancer properties of silver nanoparticles in human cancer cells. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2017; 824:32-41. [PMID: 29150048 DOI: 10.1016/j.mrgentox.2017.10.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2017] [Revised: 10/04/2017] [Accepted: 10/09/2017] [Indexed: 12/19/2022]
Abstract
Silver nanoparticles (Ag-np) were reported to be toxic to eukaryotic cells. These potentially detrimental effects of Ag-np can be advantageous in experimental therapeutics. They are currently being employed to enhance the therapeutic efficacy of cancer drugs. In this study, we demonstrate that Ag-np treatment trigger the activation of DNA-PKcs and JNK pathway at selected doses, presumably as a physiologic response to DNA damage and repair in normal and malignant cells. Ag-np altered the telomere dynamics by disrupting the shelterin complex located at the telomeres and telomere lengths. The genotoxic effect of Ag-np was not restricted to telomeres but the entire genome as Ag-np induced γ-H2AX foci formation, an indicator of global DNA damage. Inhibition of DNA-PKcs activity sensitised the cancer cells towards the cytotoxicity of Ag-np and substantiated the damaging effect of Ag-np at telomeres in human cancer cells. Abrogation of JNK mediated DNA repair and extensive damage of telomeres led to greater cell death following Ag-np treatment in DNA-PKcs inhibited cancer cells. Collectively, this study suggests that improved anti-proliferative and cytotoxic effects of Ag-np treatment in cancer cells can be achieved by the inhibition of DNA-PKcs.
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Abstract
Bacteria and viruses possess circular DNA, whereas eukaryotes with typically very large DNA molecules have had to evolve into linear chromosomes to circumvent the problem of supercoiling circular DNA of that size. Consequently, such organisms possess telomeres to cap chromosome ends. Telomeres are essentially tandem repeats of any DNA sequence that are present at the ends of chromosomes. Their biology has been an enigmatic one, involving various molecules interacting dynamically in an evolutionarily well-trimmed fashion. Telomeres range from canonical hexameric repeats in most eukaryotes to unimaginably random retrotransposons, which attach to chromosome ends and reverse-transcribe to DNA in some plants and insects. Telomeres invariably associate with specialised protein complexes that envelop it, also regulating access of the ends to legitimate enzymes involved in telomere metabolism. They also transcribe into repetitive RNA which also seems to be playing significant roles in telomere maintenance. Telomeres thus form the intersection of DNA, protein, and RNA molecules acting in concert to maintain chromosome integrity. Telomere biology is emerging to appear ever more complex than previously envisaged, with the continual discovery of more molecules and interplays at the telomeres. This review also includes a section dedicated to the history of telomere biology, and intends to target the scientific audience new to the field by rendering an understanding of the phenomenon of chromosome end protection at large, with more emphasis on the biology of human telomeres. The review provides an update on the field and mentions the questions that need to be addressed.
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Affiliation(s)
- Shriram Venkatesan
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, 117597 Singapore, Singapore.
| | - Aik Kia Khaw
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, 117597 Singapore, Singapore.
- Clinical Research Unit, Khoo Teck Puat Hospital, 768828 Singapore, Singapore.
| | - Manoor Prakash Hande
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, 117597 Singapore, Singapore.
- Tembusu College, National University of Singapore, 138598 Singapore, Singapore.
- VIT University, Vellore 632014, India.
- Mangalore University, Mangalore 574199, India.
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20
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Piekna-Przybylska D, Sharma G, Maggirwar SB, Bambara RA. Deficiency in DNA damage response, a new characteristic of cells infected with latent HIV-1. Cell Cycle 2017; 16:968-978. [PMID: 28388353 DOI: 10.1080/15384101.2017.1312225] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
Abstract
Viruses can interact with host cell molecules responsible for the recognition and repair of DNA lesions, resulting in dysfunctional DNA damage response (DDR). Cells with inefficient DDR are more vulnerable to therapeutic approaches that target DDR, thereby raising DNA damage to a threshold that triggers apoptosis. Here, we demonstrate that 2 Jurkat-derived cell lines with incorporated silent HIV-1 provirus show increases in DDR signaling that responds to formation of double strand DNA breaks (DSBs). We found that phosphorylation of histone H2AX on Ser139 (gamma-H2AX), a biomarker of DSBs, and phosphorylation of ATM at Ser1981, Chk2 at Thr68, and p53 at Ser15, part of signaling pathways associated with DSBs, are elevated in these cells. These results indicate a DDR defect even though the virus is latent. DDR-inducing agents, specifically high doses of nucleoside RT inhibitors (NRTIs), caused greater increases in gamma-H2AX levels in latently infected cells. Additionally, latently infected cells are more susceptible to long-term exposure to G-quadruplex stabilizing agents, and this effect is enhanced when the agent is combined with an inhibitor targeting DNA-PK, which is crucial for DSB repair and telomere maintenance. Moreover, exposing these cells to the cancer drug etoposide resulted in formation of DSBs at a higher rate than in un-infected cells. Similar effects of etoposide were also observed in population of primary memory T cells infected with latent HIV-1. Sensitivity to these agents highlights a unique vulnerability of latently infected cells, a new feature that could potentially be used in developing therapies to eliminate HIV-1 reservoirs.
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Affiliation(s)
- Dorota Piekna-Przybylska
- a Department of Microbiology and Immunology , School of Medicine and Dentistry, University of Rochester , Rochester , NY , USA
| | - Gaurav Sharma
- b Department of Electrical and Computer Engineering , University of Rochester , Rochester , NY , USA
| | - Sanjay B Maggirwar
- a Department of Microbiology and Immunology , School of Medicine and Dentistry, University of Rochester , Rochester , NY , USA
| | - Robert A Bambara
- a Department of Microbiology and Immunology , School of Medicine and Dentistry, University of Rochester , Rochester , NY , USA
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21
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Sunada S, Kanai H, Lee Y, Yasuda T, Hirakawa H, Liu C, Fujimori A, Uesaka M, Okayasu R. Nontoxic concentration of DNA-PK inhibitor NU7441 radio-sensitizes lung tumor cells with little effect on double strand break repair. Cancer Sci 2016; 107:1250-5. [PMID: 27341700 PMCID: PMC5021029 DOI: 10.1111/cas.12998] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2016] [Revised: 06/21/2016] [Accepted: 06/23/2016] [Indexed: 12/19/2022] Open
Abstract
High‐linear energy transfer (LET) heavy ions have been increasingly employed as a useful alternative to conventional photon radiotherapy. As recent studies suggested that high LET radiation mainly affects the nonhomologous end‐joining (NHEJ) pathway of DNA double strand break (DSB) repair, we further investigated this concept by evaluating the combined effect of an NHEJ inhibitor (NU7441) at a non‐toxic concentration and carbon ions. NU7441‐treated non‐small cell lung cancer (NSCLC) A549 and H1299 cells were irradiated with X‐rays and carbon ions (290 MeV/n, 50 keV/μm). Cell survival was measured by clonogenic assay. DNA DSB repair, cell cycle distribution, DNA fragmentation and cellular senescence induction were studied using a flow cytometer. Senescence‐associated protein p21 was detected by western blotting. In the present study, 0.3 μM of NU7441, nontoxic to both normal and tumor cells, caused a significant radio‐sensitization in tumor cells exposed to X‐rays and carbon ions. This concentration did not seem to cause inhibition of DNA DSB repair but induced a significant G2/M arrest, which was particularly emphasized in p53‐null H1299 cells treated with NU7441 and carbon ions. In addition, the combined treatment induced more DNA fragmentation and a higher degree of senescence in H1299 cells than in A549 cells, indicating that DNA‐PK inhibitor contributes to various modes of cell death in a p53‐dependent manner. In summary, NSCLC cells irradiated with carbon ions were radio‐sensitized by a low concentration of DNA‐PK inhibitor NU7441 through a strong G2/M cell cycle arrest. Our findings may contribute to further effective radiotherapy using heavy ions.
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Affiliation(s)
- Shigeaki Sunada
- Department of Nuclear Engineering and Management, School of Engineering, University of Tokyo, Tokyo, Japan.,Research Center for Radiation Protection, National Institute of Radiological Sciences, Chiba, Japan
| | - Hideki Kanai
- Department of Nuclear Engineering and Management, School of Engineering, University of Tokyo, Tokyo, Japan.,Research Center for Radiation Protection, National Institute of Radiological Sciences, Chiba, Japan
| | - Younghyun Lee
- Research Center for Radiation Protection, National Institute of Radiological Sciences, Chiba, Japan
| | - Takeshi Yasuda
- Research Center for Radiation Emergency Medicine, National Institute of Radiological Sciences, Chiba, Japan
| | - Hirokazu Hirakawa
- Research Center for Radiation Protection, National Institute of Radiological Sciences, Chiba, Japan
| | - Cuihua Liu
- Research Center for Radiation Protection, National Institute of Radiological Sciences, Chiba, Japan
| | - Akira Fujimori
- Research Center for Radiation Protection, National Institute of Radiological Sciences, Chiba, Japan
| | - Mitsuru Uesaka
- Department of Nuclear Engineering and Management, School of Engineering, University of Tokyo, Tokyo, Japan
| | - Ryuichi Okayasu
- Research Center for Radiation Protection, National Institute of Radiological Sciences, Chiba, Japan.
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22
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Spontaneous tumor development in bone marrow-rescued DNA-PKcs(3A/3A) mice due to dysfunction of telomere leading strand deprotection. Oncogene 2015; 35:3909-18. [PMID: 26616856 PMCID: PMC4885801 DOI: 10.1038/onc.2015.459] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Revised: 10/29/2015] [Accepted: 10/30/2015] [Indexed: 12/16/2022]
Abstract
Phosphorylation of the DNA-dependent protein kinase catalytic subunit (DNA-PKcs) at the Thr2609 cluster is essential for its complete function in DNA repair and tissue stem cell homeostasis. This phenomenon is demonstrated by congenital bone marrow failure occurring in DNA-PKcs3A/3A mutant mice, which require bone marrow transplantation (BMT) to prevent early mortality. Surprisingly, an increased incidence of spontaneous tumors, especially skin cancer, was observed in adult BMT-rescued DNA-PKcs3A/3A mice. Upon further investigation we found that spontaneous γH2AX foci occurred in DNA-PKcs3A/3A skin biopsies and primary keratinocytes and that these foci overlapped with telomeres during mitosis, indicating impairment of telomere replication and maturation. Consistently, we observed significantly elevated frequencies of telomere fusion events in DNA-PKcs3A/3A cells as compared to wild type and DNA-PKcs knockout cells. In addition, a previously identified DNA-PKcs Thr2609Pro mutation, found in breast cancer, also induces a similar impairment of telomere leading end maturation. Taken together, our current analyses indicate that the functional DNA-PKcs T2609 cluster is required to facilitate telomere leading strand maturation and prevention of genomic instability and cancer development.
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23
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Venkatesan S, Natarajan AT, Hande MP. Chromosomal instability--mechanisms and consequences. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2015; 793:176-84. [PMID: 26520388 DOI: 10.1016/j.mrgentox.2015.08.008] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2015] [Accepted: 08/21/2015] [Indexed: 01/08/2023]
Abstract
Chromosomal instability is defined as a state of numerical and/or structural chromosomal anomalies in cells. Numerous studies have documented the incidence of chromosomal instability, which acutely or chronically may lead to accelerated ageing (tissue-wide or even organismal), cancer or other genetic disorders. Potential mechanisms leading to the generation of chromosome-genome instability include erroneous/inefficient DNA repair, chromosome segregation defects, spindle assembly defects, DNA replication stress, telomere shortening/dysfunction - to name a few. Understanding the cellular and molecular mechanisms for chromosomal instability in various human cells and tissues will be useful in elucidating the cause for many age associated diseases including cancer. This approach holds a great promise for the cytogenetic assays not only for prognosis but also for diagnostic purposes in clinical settings. In this review, a multi-dimensional approach has been attempted to portray the complexity behind the incidence of chromosome-genome instability including evolutionary implications at the species level for some of the mechanisms of chromosomal instability.
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Affiliation(s)
- Shriram Venkatesan
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, 117597
| | - Adayapalam T Natarajan
- Department of Ecological and Biological Sciences, University of Tuscia, Viterbo 01100, Italy
| | - M Prakash Hande
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, 117597; Tembusu College, National University of Singapore, Singapore, 138597.
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24
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Anjomani Virmouni S, Al-Mahdawi S, Sandi C, Yasaei H, Giunti P, Slijepcevic P, Pook MA. Identification of telomere dysfunction in Friedreich ataxia. Mol Neurodegener 2015; 10:22. [PMID: 26059974 PMCID: PMC4462004 DOI: 10.1186/s13024-015-0019-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Accepted: 05/26/2015] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Friedreich ataxia (FRDA) is a progressive inherited neurodegenerative disorder caused by mutation of the FXN gene, resulting in decreased frataxin expression, mitochondrial dysfunction and oxidative stress. A recent study has identified shorter telomeres in FRDA patient leukocytes as a possible disease biomarker. RESULTS Here we aimed to investigate both telomere structure and function in FRDA cells. Our results confirmed telomere shortening in FRDA patient leukocytes and identified similar telomere shortening in FRDA patient autopsy cerebellar tissues. However, FRDA fibroblasts showed significantly longer telomeres at early passage, occurring in the absence of telomerase activity, but with activation of an alternative lengthening of telomeres (ALT)-like mechanism. These cells also showed accelerated telomere shortening as population doubling increases. Furthermore, telomere dysfunction-induced foci (TIF) analysis revealed that FRDA fibroblasts have dysfunctional telomeres. CONCLUSIONS Our finding of dysfunctional telomeres in FRDA cells provides further insight into FRDA molecular disease mechanisms, which may have implications for future FRDA therapy.
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Affiliation(s)
- Sara Anjomani Virmouni
- Division of Biosciences, Department of Life Sciences, College of Health & Life Sciences, Brunel University London, Uxbridge, UB8 3PH, UK. .,Synthetic Biology Theme, Institute of Environment, Health & Societies, Brunel University London, Uxbridge, UK.
| | - Sahar Al-Mahdawi
- Division of Biosciences, Department of Life Sciences, College of Health & Life Sciences, Brunel University London, Uxbridge, UB8 3PH, UK. .,Synthetic Biology Theme, Institute of Environment, Health & Societies, Brunel University London, Uxbridge, UK.
| | - Chiranjeevi Sandi
- Division of Biosciences, Department of Life Sciences, College of Health & Life Sciences, Brunel University London, Uxbridge, UB8 3PH, UK. .,Current address: Uro-Oncology Research Group, Cancer Research UK-Cambridge Institute, University of Cambridge, Cambridge, UK.
| | - Hemad Yasaei
- Division of Biosciences, Department of Life Sciences, College of Health & Life Sciences, Brunel University London, Uxbridge, UB8 3PH, UK.
| | - Paola Giunti
- Department of Molecular Neuroscience, Institute of Neurology, University College London, Queen Square, London, UK.
| | - Predrag Slijepcevic
- Division of Biosciences, Department of Life Sciences, College of Health & Life Sciences, Brunel University London, Uxbridge, UB8 3PH, UK.
| | - Mark A Pook
- Division of Biosciences, Department of Life Sciences, College of Health & Life Sciences, Brunel University London, Uxbridge, UB8 3PH, UK. .,Synthetic Biology Theme, Institute of Environment, Health & Societies, Brunel University London, Uxbridge, UK.
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25
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Sui J, Lin YF, Xu K, Lee KJ, Wang D, Chen BPC. DNA-PKcs phosphorylates hnRNP-A1 to facilitate the RPA-to-POT1 switch and telomere capping after replication. Nucleic Acids Res 2015; 43:5971-83. [PMID: 25999341 PMCID: PMC4499152 DOI: 10.1093/nar/gkv539] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Accepted: 05/12/2015] [Indexed: 11/13/2022] Open
Abstract
The heterogeneous nuclear ribonucleoprotein A1 (hnRNP-A1) has been implicated in telomere protection and telomerase activation. Recent evidence has further demonstrated that hnRNP-A1 plays a crucial role in maintaining newly replicated telomeric 3' overhangs and facilitating the switch from replication protein A (RPA) to protection of telomeres 1 (POT1). The role of hnRNP-A1 in telomere protection also involves DNA-dependent protein kinase catalytic subunit (DNA-PKcs), although the detailed regulation mechanism has not been clear. Here we report that hnRNP-A1 is phosphorylated by DNA-PKcs during the G2 and M phases and that DNA-PK-dependent hnRNP-A1 phosphorylation promotes the RPA-to-POT1 switch on telomeric single-stranded 3' overhangs. Consequently, in cells lacking hnRNP-A1 or DNA-PKcs-dependent hnRNP-A1 phosphorylation, impairment of the RPA-to-POT1 switch results in DNA damage response at telomeres during mitosis as well as induction of fragile telomeres. Taken together, our results indicate that DNA-PKcs-dependent hnRNP-A1 phosphorylation is critical for capping of the newly replicated telomeres and prevention of telomeric aberrations.
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Affiliation(s)
- Jiangdong Sui
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA Cancer Center, Daping Hospital, Third Military Medical University, Chongqing 400042, China
| | - Yu-Fen Lin
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Kangling Xu
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Kyung-Jong Lee
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Dong Wang
- Cancer Center, Daping Hospital, Third Military Medical University, Chongqing 400042, China
| | - Benjamin P C Chen
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
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26
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The DNA-dependent protein kinase: A multifunctional protein kinase with roles in DNA double strand break repair and mitosis. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2014; 117:194-205. [PMID: 25550082 DOI: 10.1016/j.pbiomolbio.2014.12.003] [Citation(s) in RCA: 198] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2014] [Revised: 12/16/2014] [Accepted: 12/19/2014] [Indexed: 11/21/2022]
Abstract
The DNA-dependent protein kinase (DNA-PK) is a serine/threonine protein kinase composed of a large catalytic subunit (DNA-PKcs) and the Ku70/80 heterodimer. Over the past two decades, significant progress has been made in elucidating the role of DNA-PK in non-homologous end joining (NHEJ), the major pathway for repair of ionizing radiation-induced DNA double strand breaks in human cells and recently, additional roles for DNA-PK have been reported. In this review, we will describe the biochemistry, structure and function of DNA-PK, its roles in DNA double strand break repair and its newly described roles in mitosis and other cellular processes.
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27
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Saadat M, Pashaei S, Amerizade F. Susceptibility to gastric cancer and polymorphisms of insertion/deletion at the intron 3 of the XRCC4 and VNTR at the promoter region of the XRCC5. Pathol Oncol Res 2014; 21:689-93. [PMID: 25527410 DOI: 10.1007/s12253-014-9875-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/20/2014] [Accepted: 12/05/2014] [Indexed: 12/18/2022]
Abstract
The genes encoding X-ray repair cross-complementing group 4 (XRCC4; OMIM: 194363) and 5 (XRCC5; OMIM: 194364) are involved in repair of DNA double-strand breaks. To investigating the associations between polymorphisms of Insertion/Deletion (I/D, rs28360071) in the intron 3 of the XRCC4 and VNTR in the promoter region of the XRCC5 and risk of gastric cancer, the present study was carried out. We included 159 (56 females, 103 males) with gastric cancer and 242 (75 females, 167 males) healthy blood donors frequency matched for age and gender. Using PCR-based methods, the genotypes of the study polymorphisms were determined. The alleles of VNTR XRCC5 polymorphism divided into two groups: L (0 and 1 repeats) and H (2 and 3 repeats) alleles. For the I/D XRCC4 polymorphism, after stratification of the subjects according to their family history (FH) of cancer, either the ID (OR = 3.19, 95%CI: 1.35-7.50, P = 0.008) or the DD genotypes (OR = 4.62, 95%CI: 1.63-13.0, P = 0.004) among positive FH persons, increased the risk of gastric cancer compared with the reference group (persons who have negative FH and II genotype). For the VNTR XRCC5 polymorphism, the LH + HH genotypes among positive FH persons, increased the risk of gastric cancer compared with the reference group (persons who have negative FH and LL genotype) (OR = 2.88, 95%CI: 1.34-6.18, P = 0.006). Sensitivity analysis showed that the above mentioned associations were not occurred due to the maldistribution of the genotypes among missing data. The present study suggests that both polymorphisms of the XRCC4 and XRCC5 might be risk factors for gastric cancer development especially among persons with positive FH.
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Affiliation(s)
- Mostafa Saadat
- Department of Biology, College of Sciences, Shiraz University, Shiraz, 71454, Iran,
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Tanaka H, Beam MJ, Caruana K. The presence of telomere fusion in sporadic colon cancer independently of disease stage, TP53/KRAS mutation status, mean telomere length, and telomerase activity. Neoplasia 2014; 16:814-23. [PMID: 25379018 PMCID: PMC4212252 DOI: 10.1016/j.neo.2014.08.009] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2014] [Revised: 08/19/2014] [Accepted: 08/20/2014] [Indexed: 11/25/2022] Open
Abstract
Defects in telomere maintenance can result in telomere fusions that likely play a causative role in carcinogenesis by promoting genomic instability. However, this proposition remains to be fully understood in human colon carcinogenesis. In the present study, the temporal sequence of telomere dysfunction dynamics was delineated by analyzing telomere fusion, telomere length, telomerase activity, hotspot mutations in KRAS or BRAF, and TP53 of tissue samples obtained from 18 colon cancer patients. Our results revealed that both the deficiency of p53 and the shortening of mean telomere length were not necessary for producing telomere fusions in colon tissue. In five cases, telomere fusion was observed even in tissue adjacent to cancerous lesions, suggesting that genomic instability is initiated in pathologically non-cancerous lesions. The extent of mean telomere attrition increased with lymph node invasiveness of tumors, implying that mean telomere shortening correlates with colon cancer progression. Telomerase activity was relatively higher in most cancer tissues containing mutation(s) in KRAS or BRAF and/or TP53 compared to those without these hotspot mutations, suggesting that telomerase could become fully active at the late stage of colon cancer development. Interestingly, the majority of telomere fusion junctions in colon cancer appeared to be a chromatid-type containing chromosome 7q or 12q. In sum, this meticulous correlative study not only highlights the concept that telomere fusion is present in the early stages of cancer regardless of TP53/KRAS mutation status, mean telomere length, and telomerase activity, but also provides additional insights targeting key telomere fusion junctions which may have significant implications for colon cancer diagnoses.
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Affiliation(s)
- Hiromi Tanaka
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, IN, USA
| | - Matthew J Beam
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, IN, USA
| | - Kevin Caruana
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, IN, USA
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DNA-PKcs-interacting protein KIP binding to TRF2 is required for the maintenance of functional telomeres. Biochem J 2014; 463:19-30. [DOI: 10.1042/bj20131395] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
DNA-PKcs-interacting protein KIP interacts with TRF2 and enhances the telomere binding activity of TRF2. Depletion of KIP induces telomere-damage response foci. Thus KIP plays important roles in the maintenance of functional telomeres and the regulation of telomere-associated DNA-damage response.
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30
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Misenko SM, Bunting SF. Rapid analysis of chromosome aberrations in mouse B lymphocytes by PNA-FISH. J Vis Exp 2014:51806. [PMID: 25177909 PMCID: PMC4540087 DOI: 10.3791/51806] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Defective DNA repair leads to increased genomic instability, which is the root cause of mutations that lead to tumorigenesis. Analysis of the frequency and type of chromosome aberrations in different cell types allows defects in DNA repair pathways to be elucidated. Understanding mammalian DNA repair biology has been greatly helped by the production of mice with knockouts in specific genes. The goal of this protocol is to quantify genomic instability in mouse B lymphocytes. Labeling of the telomeres using PNA-FISH probes (peptide nucleic acid - fluorescent in situ hybridization) facilitates the rapid analysis of genomic instability in metaphase chromosome spreads. B cells have specific advantages relative to fibroblasts, because they have normal ploidy and a higher mitotic index. Short-term culture of B cells therefore enables precise measurement of genomic instability in a primary cell population which is likely to have fewer secondary genetic mutations than what is typically found in transformed fibroblasts or patient cell lines.
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Affiliation(s)
- Sarah M Misenko
- Department of Molecular Biology and Biochemistry, Rutgers, the State University of New Jersey
| | - Samuel F Bunting
- Department of Molecular Biology and Biochemistry, Rutgers, the State University of New Jersey;
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Molina-Estevez FJ, Lozano ML, Navarro S, Torres Y, Grabundzija I, Ivics Z, Samper E, Bueren JA, Guenechea G. Brief report: impaired cell reprogramming in nonhomologous end joining deficient cells. Stem Cells 2014; 31:1726-30. [PMID: 23630174 DOI: 10.1002/stem.1406] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2012] [Accepted: 03/28/2013] [Indexed: 01/14/2023]
Abstract
Although there is an increasing interest in defining the role of DNA damage response mechanisms in cell reprogramming, the relevance of proteins participating in nonhomologous end joining (NHEJ), a major mechanism of DNA double-strand breaks repair, in this process remains to be investigated. Herein, we present data related to the reprogramming of primary mouse embryonic fibroblasts (MEF) from severe combined immunodeficient (Scid) mice defective in DNA-PKcs, a key protein for NHEJ. Reduced numbers of induced pluripotent stem cell (iPSC) colonies were generated from Scid cells using reprogramming lentiviral vectors (LV), being the reprogramming efficiency fourfold to sevenfold lower than that observed in wt cells. Moreover, these Scid iPSC-like clones were prematurely lost or differentiated spontaneously. While the Scid mutation neither reduce the proliferation rate nor the transduction efficacy of fibroblasts transduced with reprogramming LV, both the expression of SA-β-Gal and of P16/INK(4a) senescence markers were highly increased in Scid versus wt MEFs during the reprogramming process, accounting for the reduced reprogramming efficacy of Scid MEFs. The use of improved Sleeping Beauty transposon/transposase systems allowed us, however, to isolate DNA-PKcs-deficient iPSCs which preserved their parental genotype and hypersensitivity to ionizing radiation. This new disease-specific iPSC model would be useful to understand the physiological consequences of the DNA-PKcs mutation during development and would help to improve current cell and gene therapy strategies for the disease.
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Affiliation(s)
- F Javier Molina-Estevez
- Division of Hematopoietic Innovative Therapies (HIT), Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas (CIEMAT)/Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBER-ER), Madrid, Spain
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Differential role of nonhomologous end joining factors in the generation, DNA damage response, and myeloid differentiation of human induced pluripotent stem cells. Proc Natl Acad Sci U S A 2014; 111:8889-94. [PMID: 24889605 DOI: 10.1073/pnas.1323649111] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Nonhomologous end-joining (NHEJ) is a key pathway for efficient repair of DNA double-strand breaks (DSBs) and V(D)J recombination. NHEJ defects in humans cause immunodeficiency and increased cellular sensitivity to ionizing irradiation (IR) and are variably associated with growth retardation, microcephaly, and neurodevelopmental delay. Repair of DNA DSBs is important for reprogramming of somatic cells into induced pluripotent stem cells (iPSCs). To compare the specific contribution of DNA ligase 4 (LIG4), Artemis, and DNA-protein kinase catalytic subunit (PKcs) in this process and to gain insights into phenotypic variability associated with these disorders, we reprogrammed patient-derived fibroblast cell lines with NHEJ defects. Deficiencies of LIG4 and of DNA-PK catalytic activity, but not Artemis deficiency, were associated with markedly reduced reprogramming efficiency, which could be partially rescued by genetic complementation. Moreover, we identified increased genomic instability in LIG4-deficient iPSCs. Cell cycle synchronization revealed a severe defect of DNA repair and a G0/G1 cell cycle arrest, particularly in LIG4- and DNA-PK catalytically deficient iPSCs. Impaired myeloid differentiation was observed in LIG4-, but not Artemis- or DNA-PK-mutated iPSCs. These results indicate a critical importance of the NHEJ pathway for somatic cell reprogramming, with a major role for LIG4 and DNA-PKcs and a minor, if any, for Artemis.
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Frit P, Barboule N, Yuan Y, Gomez D, Calsou P. Alternative end-joining pathway(s): bricolage at DNA breaks. DNA Repair (Amst) 2014; 17:81-97. [PMID: 24613763 DOI: 10.1016/j.dnarep.2014.02.007] [Citation(s) in RCA: 106] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2013] [Revised: 02/01/2014] [Accepted: 02/10/2014] [Indexed: 10/25/2022]
Abstract
To cope with DNA double strand break (DSB) genotoxicity, cells have evolved two main repair pathways: homologous recombination which uses homologous DNA sequences as repair templates, and non-homologous Ku-dependent end-joining involving direct sealing of DSB ends by DNA ligase IV (Lig4). During the last two decades a third player most commonly named alternative end-joining (A-EJ) has emerged, which is defined as any Ku- or Lig4-independent end-joining process. A-EJ increasingly appears as a highly error-prone bricolage on DSBs and despite expanding exploration, it still escapes full characterization. In the present review, we discuss the mechanism and regulation of A-EJ as well as its biological relevance under physiological and pathological situations, with a particular emphasis on chromosomal instability and cancer. Whether or not it is a genuine DSB repair pathway, A-EJ is emerging as an important cellular process and understanding A-EJ will certainly be a major challenge for the coming years.
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Affiliation(s)
- Philippe Frit
- CNRS, IPBS (Institut de Pharmacologie et de Biologie Structurale), BP 64182, 205 route de Narbonne, 31077 Toulouse, Cedex4, France; Université de Toulouse, UPS, IPBS, F-31077 Toulouse, France; Equipe labellisée Ligue Nationale Contre le Cancer, France
| | - Nadia Barboule
- CNRS, IPBS (Institut de Pharmacologie et de Biologie Structurale), BP 64182, 205 route de Narbonne, 31077 Toulouse, Cedex4, France; Université de Toulouse, UPS, IPBS, F-31077 Toulouse, France; Equipe labellisée Ligue Nationale Contre le Cancer, France
| | - Ying Yuan
- CNRS, IPBS (Institut de Pharmacologie et de Biologie Structurale), BP 64182, 205 route de Narbonne, 31077 Toulouse, Cedex4, France; Université de Toulouse, UPS, IPBS, F-31077 Toulouse, France; Equipe labellisée Ligue Nationale Contre le Cancer, France
| | - Dennis Gomez
- CNRS, IPBS (Institut de Pharmacologie et de Biologie Structurale), BP 64182, 205 route de Narbonne, 31077 Toulouse, Cedex4, France; Université de Toulouse, UPS, IPBS, F-31077 Toulouse, France; Equipe labellisée Ligue Nationale Contre le Cancer, France
| | - Patrick Calsou
- CNRS, IPBS (Institut de Pharmacologie et de Biologie Structurale), BP 64182, 205 route de Narbonne, 31077 Toulouse, Cedex4, France; Université de Toulouse, UPS, IPBS, F-31077 Toulouse, France; Equipe labellisée Ligue Nationale Contre le Cancer, France.
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Krutikov K, Zheng Y, Chesney A, Huang X, Vaags AK, Evdokimova V, Hough MR, Chen E. Ectopic TLX1 expression accelerates malignancies in mice deficient in DNA-PK. PLoS One 2014; 9:e89649. [PMID: 24586935 PMCID: PMC3935916 DOI: 10.1371/journal.pone.0089649] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2013] [Accepted: 01/26/2014] [Indexed: 11/22/2022] Open
Abstract
The noncluster homeobox gene HOX11/TLX1 (TLX1) is detected at the breakpoint of the t(10;14)(q24;q11) chromosome translocation in patients with T cell acute lymphoblastic leukemia (T-ALL). This translocation results in the inappropriate expression of TLX1 in T cells. The oncogenic potential of TLX1 was demonstrated in IgHμ-TLX1Tg mice which develop mature B cell lymphoma after a long latency period, suggesting the requirement of additional mutations to initiate malignancy. To determine whether dysregulation of genes involved in the DNA damage response contributed to tumor progression, we crossed IgHμ-TLX1Tg mice with mice deficient in the DNA repair enzyme DNA-PK (PrkdcScid/Scid mice). IgHµ-TLX1TgPrkdcScid/Scid mice developed T-ALL and acute myeloid leukemia (AML) with reduced latency relative to control PrkdcScid/Scid mice. Further analysis of thymi from premalignant mice revealed greater thymic cellularity concomitant with increased thymocyte proliferation and decreased apoptotic index. Moreover, premalignant and malignant thymocytes exhibited impaired spindle checkpoint function, in association with aneuploid karyotypes. Gene expression profiling of premalignant IgHµ-TLX1TgPrkdcScid/Scid thymocytes revealed dysregulated expression of cell cycle, apoptotic and mitotic spindle checkpoint genes in double negative 2 (DN2) and DN3 stage thymocytes. Collectively, these findings reveal a novel synergy between TLX1 and impaired DNA repair pathway in leukemogenesis.
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Affiliation(s)
- Konstantin Krutikov
- Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada
- Department of Molecular and Cellular Biology, Sunnybrook Research Institute, Toronto, Ontario, Canada
| | - Yanzhen Zheng
- Department of Molecular and Cellular Biology, Sunnybrook Research Institute, Toronto, Ontario, Canada
| | - Alden Chesney
- Department of Clinical Pathology, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
| | - Xiaoyong Huang
- Department of Molecular and Cellular Biology, Sunnybrook Research Institute, Toronto, Ontario, Canada
| | - Andrea K. Vaags
- Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada
- Department of Molecular and Cellular Biology, Sunnybrook Research Institute, Toronto, Ontario, Canada
| | - Valentina Evdokimova
- Department of Molecular and Cellular Biology, Sunnybrook Research Institute, Toronto, Ontario, Canada
| | - Margaret R. Hough
- Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
- * E-mail: (EC); (MRH)
| | - Edwin Chen
- Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada
- Department of Molecular and Cellular Biology, Sunnybrook Research Institute, Toronto, Ontario, Canada
- * E-mail: (EC); (MRH)
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35
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Shim G, Ricoul M, Hempel WM, Azzam EI, Sabatier L. Crosstalk between telomere maintenance and radiation effects: A key player in the process of radiation-induced carcinogenesis. MUTATION RESEARCH. REVIEWS IN MUTATION RESEARCH 2014; 760:S1383-5742(14)00002-7. [PMID: 24486376 PMCID: PMC4119099 DOI: 10.1016/j.mrrev.2014.01.001] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2013] [Revised: 01/14/2014] [Accepted: 01/22/2014] [Indexed: 02/06/2023]
Abstract
It is well established that ionizing radiation induces chromosomal damage, both following direct radiation exposure and via non-targeted (bystander) effects, activating DNA damage repair pathways, of which the proteins are closely linked to telomeric proteins and telomere maintenance. Long-term propagation of this radiation-induced chromosomal damage during cell proliferation results in chromosomal instability. Many studies have shown the link between radiation exposure and radiation-induced changes in oxidative stress and DNA damage repair in both targeted and non-targeted cells. However, the effect of these factors on telomeres, long established as guardians of the genome, still remains to be clarified. In this review, we will focus on what is known about how telomeres are affected by exposure to low- and high-LET ionizing radiation and during proliferation, and will discuss how telomeres may be a key player in the process of radiation-induced carcinogenesis.
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Kang GY, Pyun BJ, Seo HR, Jin YB, Lee HJ, Lee YJ, Lee YS. Inhibition of Snail1-DNA-PKcs protein-protein interface sensitizes cancer cells and inhibits tumor metastasis. J Biol Chem 2013; 288:32506-32516. [PMID: 24085291 DOI: 10.1074/jbc.m113.479840] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Our previous study suggested that the DNA-dependent protein kinase catalytic subunit (DNA-PKcs) interacts with Snail1, which affects genomic instability, sensitivity to DNA-damaging agents, and migration of tumor cells by reciprocal regulation between DNA-PKcs and Snail1. Here, we further investigate that a peptide containing 7-amino acid sequences (amino acids 15-21) of Snail1 (KPNYSEL, SP) inhibits the endogenous interaction between DNA-PKcs and Snail1 through primary interaction with DNA-PKcs. SP restored the inhibited DNA-PKcs repair activity and downstream pathways. On the other hand, DNA-PKcs-mediated phosphorylation of Snail1 was inhibited by SP, which resulted in decreased Snail1 stability and Snail1 functions. However, these phenomena were only shown in p53 wild-type cells, not in p53-defective cells. From these results, it is suggested that interfering with the protein interaction between DNA-PKcs and Snail1 might be an effective strategy for sensitizing cancer cells and inhibiting tumor migration, especially in both Snail1-overexpressing and DNA-PKcs-overexpressing cancer cells with functional p53.
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Affiliation(s)
- Ga-Young Kang
- From the College of Pharmacy, Graduate School of Pharmaceutical Sciences, Ewha Womans University, Seoul 120-750
| | - Bo-Jeong Pyun
- From the College of Pharmacy, Graduate School of Pharmaceutical Sciences, Ewha Womans University, Seoul 120-750
| | - Haeng Ran Seo
- the Division of Radiation Effects, Korea Institute of Radiological and Medical Sciences, Seoul 139-706
| | - Yeung Bae Jin
- the Korea Atomic Energy Research Institute, Advanced Radiation Technology Institute, Jeongeup-si, Jeollabuk-do 580-185, Korea
| | - Hae-June Lee
- the Division of Radiation Effects, Korea Institute of Radiological and Medical Sciences, Seoul 139-706
| | - Yoon-Jin Lee
- the Division of Radiation Effects, Korea Institute of Radiological and Medical Sciences, Seoul 139-706
| | - Yun-Sil Lee
- From the College of Pharmacy, Graduate School of Pharmaceutical Sciences, Ewha Womans University, Seoul 120-750,.
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37
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Zhou X, Zhang X, Xie Y, Tanaka K, Wang B, Zhang H. DNA-PKcs inhibition sensitizes cancer cells to carbon-ion irradiation via telomere capping disruption. PLoS One 2013; 8:e72641. [PMID: 24013362 PMCID: PMC3754927 DOI: 10.1371/journal.pone.0072641] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2013] [Accepted: 07/11/2013] [Indexed: 11/18/2022] Open
Abstract
Heavy-ion irradiation induces a higher frequency of DNA double strand breaks (DSBs) which must be properly repaired. Critical shortening of telomeres can trigger DNA damage responses such as DSBs. Telomeres are very sensitive to oxidative stress such as ionizing radiation. The DNA-dependent protein kinase catalytic subunit (DNA-PKcs) is the central component in the non-homologous end joining (NHEJ) repair complex and participates in telomere maintenance. Therefore, it is expected to enhance the cell killing effect of heavy-ion irradiation via DNA-PKcs inhibition. To test this hypothesis, cellular radiosensitivity was measured by the clonal genetic assay. DNA damage repair was relatively quantified by long PCR. Apoptosis was quantified by flow-cytometric analysis of annexin V/PI double staining, and senescence was analyzed by galactosidase activity. Telomere length was semi-quantified by real-time PCR. P53 and p21 expression was determined by western blotting. Our data demonstrated that MCF-7 and HeLa cells with DNA-PKcs inhibition were more susceptible to carbon-ion irradiation than Those without DNA-PKcs inhibition. Even though NHEJ was inhibited by the DNA-PKcs specific inhibitor, NU7026, most DNA damage induced by carbon-ion irradiation was repaired within 24 hours after irradiation in both cell lines. However, potential lethal damage repair (PLDR) could not restore cellular inactivation in DNA-PKcs inhibited cells. MCF-7 cells showed extensive senescence and accelerated telomere length reduction, while HeLa cells underwent significant apoptosis after irradiation with NU7026 incubation. In addition, both cell lines with shorter telomere were more susceptible to carbon-ion radiation. Our current data suggested that DNA-PKcs inhibition could enhance cellular sensitivity to carbon-ion radiation via disturbing its functional role in telomere end protection. The combination of DNA-PKcs inhibition and carbon-ion irradiation may be an efficient method of heavy-ion therapy.
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Affiliation(s)
- Xin Zhou
- Department of Heavy Ion Radiation Medicine, Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, China
- Key Laboratory of Heavy Ion Radiation Biology and Medicine of Chinese Academy of Sciences, Lanzhou, China
- Key Laboratory of Heavy Ion Radiation Medicine of Gansu Province, Lanzhou, China
| | - Xin Zhang
- Department of Heavy Ion Radiation Medicine, Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, China
- Key Laboratory of Heavy Ion Radiation Biology and Medicine of Chinese Academy of Sciences, Lanzhou, China
- Key Laboratory of Heavy Ion Radiation Medicine of Gansu Province, Lanzhou, China
| | - Yi Xie
- Department of Heavy Ion Radiation Medicine, Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, China
- Key Laboratory of Heavy Ion Radiation Biology and Medicine of Chinese Academy of Sciences, Lanzhou, China
- Key Laboratory of Heavy Ion Radiation Medicine of Gansu Province, Lanzhou, China
| | - Kaoru Tanaka
- Radiation Risk Reduction Research Program, Research Center for Radiation Protection, National Institute of Radiological Sciences, Inage-ku, Chiba, Japan
| | - Bing Wang
- Radiation Risk Reduction Research Program, Research Center for Radiation Protection, National Institute of Radiological Sciences, Inage-ku, Chiba, Japan
| | - Hong Zhang
- Department of Heavy Ion Radiation Medicine, Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, China
- Key Laboratory of Heavy Ion Radiation Biology and Medicine of Chinese Academy of Sciences, Lanzhou, China
- Key Laboratory of Heavy Ion Radiation Medicine of Gansu Province, Lanzhou, China
- * E-mail:
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Xu H, Zou P, Chen P, Zhao L, Zhao P, Lu A. Association between the XRCC6 Promoter rs2267437 polymorphism and cancer risk: evidence based on the current literature. Genet Test Mol Biomarkers 2013; 17:607-14. [PMID: 23745766 DOI: 10.1089/gtmb.2013.0083] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND Increasing evidence suggests that the DNA repair gene XRCC6 (Ku70) may be critically involved in the aetiology of the human carcinogenesis. Many studies have investigated the association between the rs2267437 polymorphism and cancer susceptibility. However, the results of these studies have been controversial. This meta-analysis was conducted to quantitatively summarize the evidence for a relationship between the rs2267437 polymorphism and cancer risk. METHODS Electronic databases, including PUBMED and EMBASE, were searched for publications that met the inclusion criteria. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated to evaluate the strength of the association between the XRCC6 promoter rs2267437 polymorphism and cancer risk in a fixed-effects model (the Mantel-Haenszel method) or a random-effects model (the DerSimonian and Laird method), as appropriate. RESULTS A total of 13 case-control studies, involving 3675 cases and 4247 controls, investigating the XRCC6 rs2267437 polymorphism and cancer susceptibility were identified for the meta-analysis. The pooled analysis showed that there is a significant relationship between the XRCC6 rs2267437 polymorphism and cancer susceptibility (GG vs. CC: OR=1.28, 95% CI=1.03-1.60). Subgroup analyses based on the cancer type, ethnicity, and source of the controls were also performed, and these results indicated that the XRCC6 promoter rs2267437 polymorphism was associated with cancer risk in breast cancer studies (GG vs. CC: OR=1.79, 95% CI=1.25-2.56; GG vs. CG+CC: OR=1.40, 95% CI=1.01-1.95), in Asian populations (GG vs. CC: OR=1.33, 95% CI=1.01-1.74) and in population-based studies (GG vs. CC: OR=1.57, 95% CI=1.12-2.22; CG vs. CC: OR=1.35, 95% CI=1.11-1.64; GG+CG vs. CC: OR=1.37, 95% CI=1.14-1.65). CONCLUSION This meta-analysis suggests that the XRCC6 rs2267437 polymorphism may affect breast cancer susceptibility and increase the risk of cancer in Asian populations and in the general population. It is critical that further large-scale and well-designed studies be conducted to confirm the association between the rs2267437 genotype and cancer risk.
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Affiliation(s)
- Haitao Xu
- Department of Neurosurgery, The First Affiliated Hospital, Nanjing Medical University, Nanjing, China
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39
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Galati A, Micheli E, Cacchione S. Chromatin structure in telomere dynamics. Front Oncol 2013; 3:46. [PMID: 23471416 PMCID: PMC3590461 DOI: 10.3389/fonc.2013.00046] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2012] [Accepted: 02/21/2013] [Indexed: 11/13/2022] Open
Abstract
The establishment of a specific nucleoprotein structure, the telomere, is required to ensure the protection of chromosome ends from being recognized as DNA damage sites. Telomere shortening below a critical length triggers a DNA damage response that leads to replicative senescence. In normal human somatic cells, characterized by telomere shortening with each cell division, telomere uncapping is a regulated process associated with cell turnover. Nevertheless, telomere dysfunction has also been associated with genomic instability, cell transformation, and cancer. Despite the essential role telomeres play in chromosome protection and in tumorigenesis, our knowledge of the chromatin structure involved in telomere maintenance is still limited. Here we review the recent findings on chromatin modifications associated with the dynamic changes of telomeres from protected to deprotected state and their role in telomere functions.
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Affiliation(s)
- Alessandra Galati
- Dipartimento di Biologia e Biotecnologie, Istituto Pasteur - Fondazione Cenci Bolognetti, Sapienza Università di Roma Rome, Italy
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40
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Izumi N, Yamashita A, Ohno S. Integrated regulation of PIKK-mediated stress responses by AAA+ proteins RUVBL1 and RUVBL2. Nucleus 2012; 3:29-43. [PMID: 22540023 PMCID: PMC3337166 DOI: 10.4161/nucl.18926] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Proteins of the phosphatidylinositol 3-kinase-related protein kinase (PIKK) family are activated by various cellular stresses, including DNA damage, premature termination codon and nutritional status, and induce appropriate cellular responses. The importance of PIKK functions in the maintenance of genome integrity, accurate gene expression and the proper control of cell growth/proliferation is established. Recently, ATPase associated diverse cellular activities (AAA+) proteins RUVBL1 and RUVBL2 (RUVBL1/2) have been shown to be common regulators of PIKKs. The RUVBL1/2 complex regulates PIKK-mediated stress responses through physical interactions with PIKKs and by controlling PIKK mRNA levels. In this review, the functions of PIKKs in stress responses are outlined and the physiological significance of the integrated regulation of PIKKs by the RUVBL1/2 complex is presented. We also discuss a putative "PIKK regulatory chaperone complex" including other PIKK regulators, Hsp90 and the Tel2 complex.
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Affiliation(s)
- Natsuko Izumi
- Department of Molecular Biology, Yokohama City University School of Medicine, Yokohama, Japan
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41
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Lim HK, Asharani PV, Hande MP. Enhanced genotoxicity of silver nanoparticles in DNA repair deficient Mammalian cells. Front Genet 2012; 3:104. [PMID: 22707954 PMCID: PMC3374476 DOI: 10.3389/fgene.2012.00104] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2012] [Accepted: 05/21/2012] [Indexed: 11/25/2022] Open
Abstract
Silver nanoparticles (Ag-np) have been used in medicine and commercially due to their anti-microbial properties. Therapeutic potentials of these nanoparticles are being explored extensively despite the lack of information on their mechanism of action at molecular and cellular level. Here, we have investigated the DNA damage response and repair following Ag-np treatment in mammalian cells. Studies have shown that Ag-np exerts genotoxicity through double-strand breaks (DSBs). DNA-PKcs, the catalytic subunit of DNA dependent protein kinase, is an important caretaker of the genome which is known to be the main player mediating Non-homologous End-Joining (NHEJ) repair pathway. We hypothesize that DNA-PKcs is responsible for the repair of Ag-np induced DNA damage. In vitro studies have been carried out to investigate both cytotoxicity and genotoxicity induced by Ag-np in normal human cells, DNA-PKcs proficient, and deficient mammalian cells. Chemical inhibition of DNA-PKcs activity with NU7026, an ATP-competitive inhibitor of DNA-PKcs, has been performed to further validate the role of DNA-PKcs in this model. Our results suggest that Ag-np induced more prominent dose-dependent decrease in cell viability in DNA-PKcs deficient or inhibited cells. The deficiency or inhibition of DNA-PKcs renders the cells with higher susceptibility to DNA damage and genome instability which in turn contributed to greater cell cycle arrest/cell death. These findings support the fact that DNA-PKcs is involved in the repair of Ag-np induced genotoxicity and NHEJ repair pathway and DNA-PKcs particularly is activated to safeguard the genome upon Ag-np exposure.
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Affiliation(s)
- Hui Kheng Lim
- Genome Stability Laboratory, Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore Singapore
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Bau DT, Lin CC, Chiu CF, Tsai MH. Role of nonhomologous end-joining in oral cancer and personalized pharmacogenomics. Biomedicine (Taipei) 2012. [DOI: 10.1016/j.biomed.2011.12.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
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Yang MD, Tsai CW, Chang WS, Tsou YA, Wu CN, Bau DT. Predictive role of XRCC5/ XRCC6 genotypes in digestive system cancers. World J Gastrointest Oncol 2011; 3:175-81. [PMID: 22224172 PMCID: PMC3251741 DOI: 10.4251/wjgo.v3.i12.175] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/22/2011] [Revised: 10/06/2011] [Accepted: 10/14/2011] [Indexed: 02/05/2023] Open
Abstract
Cancers are a worldwide concern; oral, esophageal and gastrointestinal cancers represent important causes of cancer-related mortality and contribute to a significant burden of human health. The DNA repair systems are the genome caretakers, playing a critical role in the initiation and progression of cancers. However, the association between the genomic variations of DNA repair genes and cancer susceptibility is not well understood. This review focuses on the polymorphic genotypes of the non-homologous end-joining DNA repair system, highlighting the role of two genes of this pathway, XRCC5 and XRCC6, in the susceptibility to digestive system cancers and discussing their potential contributions to personalized medicine.
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Affiliation(s)
- Mei-Due Yang
- Mei-Due Yang, Chia-Wen Tsai, Wen-Shin Chang, Yung-An Tsou, Cheng-Nan Wu, Da-Tian Bau, Terry Fox Cancer Research Laboratory, China Medical University Hospital, 2 Yuh-Der Road, Taichung 40402, Taiwan, China
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Rad51 and DNA-PKcs are involved in the generation of specific telomere aberrations induced by the quadruplex ligand 360A that impair mitotic cell progression and lead to cell death. Cell Mol Life Sci 2011; 69:629-40. [PMID: 21773671 PMCID: PMC3265728 DOI: 10.1007/s00018-011-0767-6] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2011] [Revised: 06/16/2011] [Accepted: 06/30/2011] [Indexed: 11/18/2022]
Abstract
Functional telomeres are protected from non-homologous end-joining (NHEJ) and homologous recombination (HR) DNA repair pathways. Replication is a critical period for telomeres because of the requirement for reconstitution of functional protected telomere conformations, a process that involves DNA repair proteins. Using knockdown of DNA-PKcs and Rad51 expression in three different cell lines, we demonstrate the respective involvement of NHEJ and HR in the formation of telomere aberrations induced by the G-quadruplex ligand 360A during or after replication. HR contributed to specific chromatid-type aberrations (telomere losses and doublets) affecting the lagging strand telomeres, whereas DNA-PKcs-dependent NHEJ was responsible for sister telomere fusions as a direct consequence of G-quadruplex formation and/or stabilization induced by 360A on parental telomere G strands. NHEJ and HR activation at telomeres altered mitotic progression in treated cells. In particular, NHEJ-mediated sister telomere fusions were associated with altered metaphase-anaphase transition and anaphase bridges and resulted in cell death during mitosis or early G1. Collectively, these data elucidate specific molecular and cellular mechanisms triggered by telomere targeting by the G-quadruplex ligand 360A, leading to cancer cell death.
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Bau DT, Tsai CW, Wu CN. Role of the XRCC5/XRCC6 dimer in carcinogenesis and pharmacogenomics. Pharmacogenomics 2011; 12:515-34. [PMID: 21521024 DOI: 10.2217/pgs.10.209] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Over the past few decades, the incidence of cancer has rapidly increased all over the world and cancer remains a major threat to public health. It is believed that cancer results from a series of genetic alterations that lead to the progressive disorder of the normal mechanisms controlling cell proliferation, differentiation, death and/or genomic stability. The response of the cell to genetic injury and its ability to maintain genomic stability by means of a variety of DNA repair mechanisms are therefore essential in preventing tumor initiation and progression. From the same viewpoint, the relative role of DNA repair as a biomarker for prognosis, predictor of drug and therapy responses or indeed as a target for novel gene therapy, is very promising. In this article, we have summarized the studies investigating the association between the XRCC5/XRCC6 dimer and the susceptibility to multiple cancers and discuss its role in carcinogenesis and its potential application to anticancer drug discovery.
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Affiliation(s)
| | - Chia-Wen Tsai
- Terry Fox Cancer Research Laboratory, China Medical University Hospital, 2 Yuh-Der Road, Taichung, 404 Taiwan, Republic of China
| | - Cheng-Nan Wu
- Terry Fox Cancer Research Laboratory, China Medical University Hospital, 2 Yuh-Der Road, Taichung, 404 Taiwan, Republic of China
- Department of Medical Laboratory Science & Biotechnology, Central-Taiwan University of Science & Technology, Taichung, Taiwan, Republic of China
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Different DNA-PKcs functions in the repair of radiation-induced and spontaneous DSBs within interstitial telomeric sequences. Chromosoma 2011; 120:309-19. [PMID: 21359527 DOI: 10.1007/s00412-011-0313-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2011] [Revised: 02/03/2011] [Accepted: 02/03/2011] [Indexed: 10/18/2022]
Abstract
Interstitial telomeric sequences (ITSs) in hamster cells are hot spots for spontaneous and induced chromosome aberrations (CAs). Most data on ITS instability to date have been obtained in DNA repair-proficient cells. The classical non-homologous end joining repair pathway (C-NHEJ), which is the principal double strand break (DSB) repair mechanism in mammalian cells, is thought to restore the morphologically correct chromosome structure. The production of CAs thus involves DNA-PKcs-independent repair pathways. In our current study, we investigated the participation of DNA-PKcs from the C-NHEJ pathway in the repair of spontaneous or radiation-induced DSBs in ITSs using wild-type and DNA-PKcs mutant Chinese hamster ovary cells. Our data demonstrate that DNA-PKcs stabilizes spontaneous DSBs within ITSs from the chromosome 9 long arm, leading to the formation of terminal deletions. In addition, we show that DNA-PKcs-dependent C-NHEJ is employed following radiation-induced DSBs in other ITSs and restores morphologically correct chromosomes, whereas DNA-PKcs independent mechanisms co-exist in DNA-PKcs proficient cells leading to an excess of CAs within ITSs.
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Double-strand breaks and the concept of short- and long-term epigenetic memory. Chromosoma 2010; 120:129-49. [PMID: 21174214 DOI: 10.1007/s00412-010-0305-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2010] [Accepted: 12/06/2010] [Indexed: 12/17/2022]
Abstract
Double-strand breaks represent an extremely cytolethal form of DNA damage and thus pose a serious threat to the preservation of genetic and epigenetic information. Though it is well-known that double-strand breaks such as those generated by ionising radiation are among the principal causative factors behind mutations, chromosomal aberrations, genetic instability and carcinogenesis, significantly less is known about the epigenetic consequences of double-strand break formation and repair for carcinogenesis. Double-strand break repair is a highly coordinated process that requires the unravelling of the compacted chromatin structure to facilitate repair machinery access and then restoration of the original undamaged chromatin state. Recent experimental findings have pointed to a potential mechanism for double-strand break-induced epigenetic silencing. This review will discuss some of the key epigenetic regulatory processes involved in double-strand break (DSB) repair and how incomplete or incorrect restoration of chromatin structure can leave a DSB-induced epigenetic memory of damage with potentially pathological repercussions.
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Zhou FX, Xiong J, Luo ZG, Dai J, Yu HJ, Liao ZK, Lei H, Xie CH, Zhou YF. cDNA Expression Analysis of a Human Radiosensitive-Radioresistant Cell Line Model Identifies Telomere Function as a Hallmark of Radioresistance. Radiat Res 2010; 174:550-7. [DOI: 10.1667/rr1657.1] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Gurung RL, Lim SN, Khaw AK, Soon JFF, Shenoy K, Mohamed Ali S, Jayapal M, Sethu S, Baskar R, Hande MP. Thymoquinone induces telomere shortening, DNA damage and apoptosis in human glioblastoma cells. PLoS One 2010; 5:e12124. [PMID: 20711342 PMCID: PMC2920825 DOI: 10.1371/journal.pone.0012124] [Citation(s) in RCA: 108] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2010] [Accepted: 06/22/2010] [Indexed: 12/15/2022] Open
Abstract
Background A major concern of cancer chemotherapy is the side effects caused by the non-specific targeting of both normal and cancerous cells by therapeutic drugs. Much emphasis has been placed on discovering new compounds that target tumour cells more efficiently and selectively with minimal toxic effects on normal cells. Methodology/Principal Findings The cytotoxic effect of thymoquinone, a component derived from the plant Nigella sativa, was tested on human glioblastoma and normal cells. Our findings demonstrated that glioblastoma cells were more sensitive to thymoquinone-induced antiproliferative effects. Thymoquinone induced DNA damage, cell cycle arrest and apoptosis in the glioblastoma cells. It was also observed that thymoquinone facilitated telomere attrition by inhibiting the activity of telomerase. In addition to these, we investigated the role of DNA-PKcs on thymoquinone mediated changes in telomere length. Telomeres in glioblastoma cells with DNA-PKcs were more sensitive to thymoquinone mediated effects as compared to those cells deficient in DNA-PKcs. Conclusions/Significance Our results indicate that thymoquinone induces DNA damage, telomere attrition by inhibiting telomerase and cell death in glioblastoma cells. Telomere shortening was found to be dependent on the status of DNA-PKcs. Collectively, these data suggest that thymoquinone could be useful as a potential chemotherapeutic agent in the management for brain tumours.
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Affiliation(s)
- Resham Lal Gurung
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Shi Ni Lim
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Aik Kia Khaw
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Jasmine Fen Fen Soon
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Kirthan Shenoy
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Safiyya Mohamed Ali
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Manikandan Jayapal
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Swaminathan Sethu
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Rajamanickam Baskar
- Division of Cellular and Molecular Research, Department of Radiation Oncology, National Cancer Centre, Singapore, Singapore
| | - M. Prakash Hande
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
- * E-mail:
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Bombarde O, Boby C, Gomez D, Frit P, Giraud-Panis MJ, Gilson E, Salles B, Calsou P. TRF2/RAP1 and DNA-PK mediate a double protection against joining at telomeric ends. EMBO J 2010; 29:1573-84. [PMID: 20407424 DOI: 10.1038/emboj.2010.49] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2009] [Accepted: 03/04/2010] [Indexed: 11/09/2022] Open
Abstract
DNA-dependent protein kinase (DNA-PK) is a double-strand breaks repair complex, the subunits of which (KU and DNA-PKcs) are paradoxically present at mammalian telomeres. Telomere fusion has been reported in cells lacking these proteins, raising two questions: how is DNA-PK prevented from initiating classical ligase IV (LIG4)-dependent non-homologous end-joining (C-NHEJ) at telomeres and how is the backup end-joining (EJ) activity (B-NHEJ) that operates at telomeres under conditions of C-NHEJ deficiency controlled? To address these questions, we have investigated EJ using plasmid substrates bearing double-stranded telomeric tracks and human cell extracts with variable C-NHEJ or B-NHEJ activity. We found that (1) TRF2/RAP1 prevents C-NHEJ-mediated end fusion at the initial DNA-PK end binding and activation step and (2) DNA-PK counteracts a potent LIG4-independent EJ mechanism. Thus, telomeres are protected against EJ by a lock with two bolts. These results account for observations with mammalian models and underline the importance of alternative non-classical EJ pathways for telomere fusions in cells.
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Affiliation(s)
- Oriane Bombarde
- Institut de Pharmacologie et de Biologie Structurale, Toulouse, France
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