151
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High-Risk Alphapapillomavirus Oncogenes Impair the Homologous Recombination Pathway. J Virol 2017; 91:JVI.01084-17. [PMID: 28768872 DOI: 10.1128/jvi.01084-17] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Accepted: 07/28/2017] [Indexed: 01/25/2023] Open
Abstract
Persistent high-risk genus human Alphapapillomavirus (HPV) infections cause nearly every cervical carcinoma and a subset of tumors in the oropharyngeal tract. During the decades required for HPV-associated tumorigenesis, the cellular genome becomes significantly destabilized. Our analysis of cervical tumors from four separate data sets found a significant upregulation of the homologous-recombination (HR) pathway genes. The increased abundance of HR proteins can be replicated in primary cells by expression of the two HPV oncogenes (E6 and E7) required for HPV-associated transformation. HPV E6 and E7 also enhanced the ability of HR proteins to form repair foci, and yet both E6 and E7 reduce the ability of the HR pathway to complete double-strand break (DSB) repair by about 50%. The HPV oncogenes hinder HR by allowing the process to begin at points in the cell cycle when the lack of a sister chromatid to serve as a homologous template prevents completion of the repair. Further, HPV E6 attenuates repair by causing RAD51 to be mislocalized away from both transient and persistent DSBs, whereas HPV E7 is only capable of impairing RAD51 localization to transient lesions. Finally, we show that the inability to robustly repair DSBs causes some of these lesions to be more persistent, a phenotype that correlates with increased integration of episomal DNA. Together, these data support our hypothesis that HPV oncogenes contribute to the genomic instability observed in HPV-associated malignancies by attenuating the repair of damaged DNA.IMPORTANCE This study expands the understanding of HPV biology, establishing a direct role for both HPV E6 and E7 in the destabilization of the host genome by blocking the homologous repair of DSBs. To our knowledge, this is the first time that both viral oncogenes were shown to disrupt this DSB repair pathway. We show that HPV E6 and E7 allow HR to initiate at an inappropriate part of the cell cycle. The mislocalization of RAD51 away from DSBs in cells expressing HPV E6 and E7 hinders HR through a distinct mechanism. These observations have broad implications. The impairment of HR by HPV oncogenes may be targeted for treatment of HPV+ malignancies. Further, this attenuation of repair suggests HPV oncogenes may contribute to tumorigenesis by promoting the integration of the HPV genome, a common feature of HPV-transformed cells. Our data support this idea since HPV E6 stimulates the integration of episomes.
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152
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Betts JA, Moradi Marjaneh M, Al-Ejeh F, Lim YC, Shi W, Sivakumaran H, Tropée R, Patch AM, Clark MB, Bartonicek N, Wiegmans AP, Hillman KM, Kaufmann S, Bain AL, Gloss BS, Crawford J, Kazakoff S, Wani S, Wen SW, Day B, Möller A, Cloonan N, Pearson J, Brown MA, Mercer TR, Waddell N, Khanna KK, Dray E, Dinger ME, Edwards SL, French JD. Long Noncoding RNAs CUPID1 and CUPID2 Mediate Breast Cancer Risk at 11q13 by Modulating the Response to DNA Damage. Am J Hum Genet 2017; 101:255-266. [PMID: 28777932 PMCID: PMC5544418 DOI: 10.1016/j.ajhg.2017.07.007] [Citation(s) in RCA: 66] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Accepted: 07/10/2017] [Indexed: 02/06/2023] Open
Abstract
Breast cancer risk is strongly associated with an intergenic region on 11q13. We have previously shown that the strongest risk-associated SNPs fall within a distal enhancer that regulates CCND1. Here, we report that, in addition to regulating CCND1, this enhancer regulates two estrogen-regulated long noncoding RNAs, CUPID1 and CUPID2. We provide evidence that the risk-associated SNPs are associated with reduced chromatin looping between the enhancer and the CUPID1 and CUPID2 bidirectional promoter. We further show that CUPID1 and CUPID2 are predominantly expressed in hormone-receptor-positive breast tumors and play a role in modulating pathway choice for the repair of double-strand breaks. These data reveal a mechanism for the involvement of this region in breast cancer.
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MESH Headings
- Breast Neoplasms/genetics
- Cell Line, Tumor
- Chromatin/metabolism
- Chromosomes, Human, Pair 11/genetics
- Cyclin D1/genetics
- DNA Breaks, Double-Stranded
- DNA Damage/genetics
- DNA Repair/genetics
- Enhancer Elements, Genetic/genetics
- Estrogens/metabolism
- Female
- Gene Expression Regulation, Neoplastic
- Genetic Predisposition to Disease/genetics
- Humans
- MCF-7 Cells
- Polymorphism, Single Nucleotide/genetics
- Promoter Regions, Genetic/genetics
- RNA Interference
- RNA, Long Noncoding/genetics
- RNA, Small Interfering/genetics
- RNA, Guide, CRISPR-Cas Systems
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Affiliation(s)
- Joshua A Betts
- Cancer Division, QIMR Berghofer Medical Research Institute, Brisbane, QLD 4006, Australia; School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, QLD 4072, Australia
| | - Mahdi Moradi Marjaneh
- Cancer Division, QIMR Berghofer Medical Research Institute, Brisbane, QLD 4006, Australia
| | - Fares Al-Ejeh
- Cancer Division, QIMR Berghofer Medical Research Institute, Brisbane, QLD 4006, Australia
| | - Yi Chieh Lim
- Cancer Division, QIMR Berghofer Medical Research Institute, Brisbane, QLD 4006, Australia
| | - Wei Shi
- Cancer Division, QIMR Berghofer Medical Research Institute, Brisbane, QLD 4006, Australia
| | - Haran Sivakumaran
- Cancer Division, QIMR Berghofer Medical Research Institute, Brisbane, QLD 4006, Australia
| | - Romain Tropée
- Queensland University of Technology at the Translational Research Institute, Brisbane, QLD 4102, Australia
| | - Ann-Marie Patch
- Cancer Division, QIMR Berghofer Medical Research Institute, Brisbane, QLD 4006, Australia
| | - Michael B Clark
- Department of Psychiatry, University of Oxford, Warneford Hospital, Oxford OX1 2JD, UK; Garvan Institute of Medical Research, Sydney, NSW 2010, Australia
| | - Nenad Bartonicek
- Garvan Institute of Medical Research, Sydney, NSW 2010, Australia; St. Vincent's Clinical School, Faculty of Medicine, University of New South Wales, Sydney, NSW 2052, Australia
| | - Adrian P Wiegmans
- Cancer Division, QIMR Berghofer Medical Research Institute, Brisbane, QLD 4006, Australia
| | - Kristine M Hillman
- Cancer Division, QIMR Berghofer Medical Research Institute, Brisbane, QLD 4006, Australia
| | - Susanne Kaufmann
- Cancer Division, QIMR Berghofer Medical Research Institute, Brisbane, QLD 4006, Australia
| | - Amanda L Bain
- Cancer Division, QIMR Berghofer Medical Research Institute, Brisbane, QLD 4006, Australia
| | - Brian S Gloss
- Garvan Institute of Medical Research, Sydney, NSW 2010, Australia; St. Vincent's Clinical School, Faculty of Medicine, University of New South Wales, Sydney, NSW 2052, Australia
| | - Joanna Crawford
- Institute for Molecular Bioscience, University of Queensland, Brisbane, QLD 4072, Australia
| | - Stephen Kazakoff
- Cancer Division, QIMR Berghofer Medical Research Institute, Brisbane, QLD 4006, Australia
| | - Shivangi Wani
- Cancer Division, QIMR Berghofer Medical Research Institute, Brisbane, QLD 4006, Australia
| | - Shu W Wen
- Cancer Division, QIMR Berghofer Medical Research Institute, Brisbane, QLD 4006, Australia
| | - Bryan Day
- Cancer Division, QIMR Berghofer Medical Research Institute, Brisbane, QLD 4006, Australia
| | - Andreas Möller
- Cancer Division, QIMR Berghofer Medical Research Institute, Brisbane, QLD 4006, Australia
| | - Nicole Cloonan
- Cancer Division, QIMR Berghofer Medical Research Institute, Brisbane, QLD 4006, Australia
| | - John Pearson
- Cancer Division, QIMR Berghofer Medical Research Institute, Brisbane, QLD 4006, Australia
| | - Melissa A Brown
- School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, QLD 4072, Australia
| | - Timothy R Mercer
- Garvan Institute of Medical Research, Sydney, NSW 2010, Australia; St. Vincent's Clinical School, Faculty of Medicine, University of New South Wales, Sydney, NSW 2052, Australia
| | - Nicola Waddell
- Cancer Division, QIMR Berghofer Medical Research Institute, Brisbane, QLD 4006, Australia
| | - Kum Kum Khanna
- Cancer Division, QIMR Berghofer Medical Research Institute, Brisbane, QLD 4006, Australia
| | - Eloise Dray
- Queensland University of Technology at the Translational Research Institute, Brisbane, QLD 4102, Australia; Queensland University of Technology, Institute of Health and Biomedical Innovation, Brisbane, QLD 4059, Australia
| | - Marcel E Dinger
- Garvan Institute of Medical Research, Sydney, NSW 2010, Australia; St. Vincent's Clinical School, Faculty of Medicine, University of New South Wales, Sydney, NSW 2052, Australia
| | - Stacey L Edwards
- Cancer Division, QIMR Berghofer Medical Research Institute, Brisbane, QLD 4006, Australia.
| | - Juliet D French
- Cancer Division, QIMR Berghofer Medical Research Institute, Brisbane, QLD 4006, Australia.
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153
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Nickoloff JA, Jones D, Lee SH, Williamson EA, Hromas R. Drugging the Cancers Addicted to DNA Repair. J Natl Cancer Inst 2017; 109:3832892. [PMID: 28521333 PMCID: PMC5436301 DOI: 10.1093/jnci/djx059] [Citation(s) in RCA: 103] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2016] [Accepted: 03/10/2017] [Indexed: 12/29/2022] Open
Abstract
Defects in DNA repair can result in oncogenic genomic instability. Cancers occurring from DNA repair defects were once thought to be limited to rare inherited mutations (such as BRCA1 or 2). It now appears that a clinically significant fraction of cancers have acquired DNA repair defects. DNA repair pathways operate in related networks, and cancers arising from loss of one DNA repair component typically become addicted to other repair pathways to survive and proliferate. Drug inhibition of the rescue repair pathway prevents the repair-deficient cancer cell from replicating, causing apoptosis (termed synthetic lethality). However, the selective pressure of inhibiting the rescue repair pathway can generate further mutations that confer resistance to the synthetic lethal drugs. Many such drugs currently in clinical use inhibit PARP1, a repair component to which cancers arising from inherited BRCA1 or 2 mutations become addicted. It is now clear that drugs inducing synthetic lethality may also be therapeutic in cancers with acquired DNA repair defects, which would markedly broaden their applicability beyond treatment of cancers with inherited DNA repair defects. Here we review how each DNA repair pathway can be attacked therapeutically and evaluate DNA repair components as potential drug targets to induce synthetic lethality. Clinical use of drugs targeting DNA repair will markedly increase when functional and genetic loss of repair components are consistently identified. In addition, future therapies will exploit artificial synthetic lethality, where complementary DNA repair pathways are targeted simultaneously in cancers without DNA repair defects.
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Affiliation(s)
- Jac A Nickoloff
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, CO, USA
| | - Dennie Jones
- Department of Medicine and the Cancer Center, University of Florida Health, Gainesville, FL, USA
| | - Suk-Hee Lee
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Elizabeth A Williamson
- Department of Medicine and the Cancer Center, University of Florida Health, Gainesville, FL, USA
| | - Robert Hromas
- Department of Medicine and the Cancer Center, University of Florida Health, Gainesville, FL, USA
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154
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Application of the gene editing tool, CRISPR-Cas9, for treating neurodegenerative diseases. Neurochem Int 2017; 112:187-196. [PMID: 28732771 DOI: 10.1016/j.neuint.2017.07.007] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2017] [Revised: 06/12/2017] [Accepted: 07/16/2017] [Indexed: 12/26/2022]
Abstract
Increased accumulation of transcribed protein from the damaged DNA and reduced DNA repair capability contributes to numerous neurological diseases for which effective treatments are lacking. Gene editing techniques provide new hope for replacing defective genes and DNA associated with neurological diseases. With advancements in using such editing tools as zinc finger nucleases (ZFNs), meganucleases, and transcription activator-like effector nucleases (TALENs), etc., scientists are able to design DNA-binding proteins, which can make precise double-strand breaks (DSBs) at the target DNA. Recent developments with the CRISPR-Cas9 gene-editing technology has proven to be more precise and efficient when compared to most other gene-editing techniques. Two methods, non-homologous end joining (NHEJ) and homology-direct repair (HDR), are used in CRISPR-Cas9 system to efficiently excise the defective genes and incorporate exogenous DNA at the target site. In this review article, we provide an overview of the CRISPR-Cas9 methodology, including its molecular mechanism, with a focus on how in this gene-editing tool can be used to counteract certain genetic defects associated with neurological diseases. Detailed understanding of this new tool could help researchers design specific gene editing strategies to repair genetic disorders in selective neurological diseases.
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155
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Li L, Poon HY, Hildebrandt MR, Monckton EA, Germain DR, Fahlman RP, Godbout R. Role for RIF1-interacting partner DDX1 in BLM recruitment to DNA double-strand breaks. DNA Repair (Amst) 2017; 55:47-63. [DOI: 10.1016/j.dnarep.2017.05.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Revised: 05/01/2017] [Accepted: 05/02/2017] [Indexed: 01/13/2023]
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156
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The anaphase promoting complex impacts repair choice by protecting ubiquitin signalling at DNA damage sites. Nat Commun 2017; 8:15751. [PMID: 28604711 PMCID: PMC5472795 DOI: 10.1038/ncomms15751] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Accepted: 04/25/2017] [Indexed: 01/06/2023] Open
Abstract
Double-strand breaks (DSBs) are repaired through two major pathways, homology-directed recombination (HDR) and non-homologous end joining (NHEJ). While HDR can only occur in S/G2, NHEJ can happen in all cell cycle phases (except mitosis). How then is the repair choice made in S/G2 cells? Here we provide evidence demonstrating that APCCdh1 plays a critical role in choosing the repair pathways in S/G2 cells. Our results suggest that the default for all DSBs is to recruit 53BP1 and RIF1. BRCA1 is blocked from being recruited to broken ends because its recruitment signal, K63-linked poly-ubiquitin chains on histones, is actively destroyed by the deubiquitinating enzyme USP1. We show that the removal of USP1 depends on APCCdh1 and requires Chk1 activation known to be catalysed by ssDNA-RPA-ATR signalling at the ends designated for HDR, linking the status of end processing to RIF1 or BRCA1 recruitment. The choice between homologous recombination and non-homologous end-joining is largely influenced by cell cycle. Here the authors show that APCCdh1 promotes homologous recombination by removing USP1, allowing polyubiquitinated histones to recruit BRCA1.
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157
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A BRCA1-Dependent DNA Damage Response in the Regenerating Adult Peripheral Nerve Milieu. Mol Neurobiol 2017; 55:4051-4067. [PMID: 28585187 DOI: 10.1007/s12035-017-0574-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2016] [Accepted: 04/25/2017] [Indexed: 10/19/2022]
Abstract
It is not generally appreciated that DNA repair machinery has a critical role in the remodeling of neurons that adopt a regenerative phenotype. We identified that breast cancer 1 (BRCA1)-dependent DNA activity, previously well known to repair cancer cells, is active in adult peripheral neurons and Schwann cells during their injury and regeneration response. Temporary or partial loss of BRCA1 or blockade of its intraneuronal nuclear entry impaired outgrowth in neurons in vitro and impacted nerve regeneration and functional recovery in vivo. We found that distal axonal injury triggered a BRCA1-dependent DNA damage response (DDR) signal in neuronal soma. BRCA1 also supported an enabling transcriptional program of injured neurons and supporting Schwann cells. Our findings indicate that BRCA1 offers prominent functional roles in neurons and glial cells including key support for their physical and molecular integrity. Since BRCA1 mutations are common in humans, this function of BRCA1 in peripheral neurons and their glial partners warrants attention.
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158
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Duheron V, Nilles N, Pecenko S, Martinelli V, Fahrenkrog B. Localisation of Nup153 and SENP1 to nuclear pore complexes is required for 53BP1-mediated DNA double-strand break repair. J Cell Sci 2017; 130:2306-2316. [PMID: 28576968 DOI: 10.1242/jcs.198390] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2016] [Accepted: 05/28/2017] [Indexed: 12/28/2022] Open
Abstract
The nuclear basket of nuclear pore complexes (NPCs) is composed of three nucleoporins: Nup153, Nup50 and Tpr. Nup153 has a role in DNA double-strand break (DSB) repair by promoting nuclear import of 53BP1 (also known as TP53BP1), a mediator of the DNA damage response. Here, we provide evidence that loss of Nup153 compromises 53BP1 sumoylation, a prerequisite for efficient accumulation of 53BP1 at DSBs. Depletion of Nup153 resulted in reduced SUMO1 modification of 53BP1 and the displacement of the SUMO protease SENP1 from NPCs. Artificial tethering of SENP1 to NPCs restored non-homologous end joining (NHEJ) in the absence of Nup153 and re-established 53BP1 sumoylation. Furthermore, Nup50 and Tpr, the two other nuclear basket nucleoporins, also contribute to proper DSB repair, in a manner distinct from Nup153. Similar to the role of Nup153, Tpr is implicated in NHEJ and homologous recombination (HR), whereas loss of Nup50 only affects NHEJ. Despite the requirement of all three nucleoporins for accurate NHEJ, only Nup153 is needed for proper nuclear import of 53BP1 and SENP1-dependent sumoylation of 53BP1. Our data support the role of Nup153 as an important regulator of 53BP1 activity and efficient NHEJ.
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Affiliation(s)
- Vincent Duheron
- Laboratory Biology of the Nucleus, Institute for Molecular Biology and Medicine, Université Libre de Bruxelles, Charleroi 6041, Belgium
| | - Nadine Nilles
- Laboratory Biology of the Nucleus, Institute for Molecular Biology and Medicine, Université Libre de Bruxelles, Charleroi 6041, Belgium
| | - Sylvia Pecenko
- Laboratory Biology of the Nucleus, Institute for Molecular Biology and Medicine, Université Libre de Bruxelles, Charleroi 6041, Belgium
| | - Valérie Martinelli
- Laboratory Biology of the Nucleus, Institute for Molecular Biology and Medicine, Université Libre de Bruxelles, Charleroi 6041, Belgium
| | - Birthe Fahrenkrog
- Laboratory Biology of the Nucleus, Institute for Molecular Biology and Medicine, Université Libre de Bruxelles, Charleroi 6041, Belgium
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159
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Kan Y, Batada NN, Hendrickson EA. Human somatic cells deficient for RAD52 are impaired for viral integration and compromised for most aspects of homology-directed repair. DNA Repair (Amst) 2017; 55:64-75. [PMID: 28549257 DOI: 10.1016/j.dnarep.2017.04.006] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2016] [Revised: 03/25/2017] [Accepted: 04/27/2017] [Indexed: 01/28/2023]
Abstract
Homology-directed repair (HDR) maintains genomic integrity by eliminating lesions such as DNA double-strand breaks (DSBs), interstrand crosslinks (ICLs) and stalled replication forks and thus a deficiency in HDR is associated with genomic instability and cancer predisposition. The mechanism of HDR is best understood and most rigorously characterized in yeast. The inactivation of the fungal radiation sensitive 52 (RAD52) gene, which has both recombination mediator and single-strand annealing (SSA) activities in vitro, leads to severe HDR defects in vivo. Confusingly, however, the inactivation of murine and chicken RAD52 genes resulted in mouse and chicken cells, respectively, that were largely aphenotypic. To clarify this issue, we have generated RAD52 knockout human cell lines. Human RAD52-null cells retain a significant level of SSA activity demonstrating perforce that additional SSA-like activities must exist in human cells. Moreover, we confirmed that the SSA activity associated with RAD52 is involved in, but not absolutely required for, most HDR subpathways. Specifically, a deficiency in RAD52 impaired the repair of DNA DSBs and intriguingly decreased the random integration of recombinant adeno-associated virus (rAAV). Finally, an analysis of pan-cancer genome data from The Cancer Genome Atlas (TCGA) revealed an association between aberrant levels of RAD52 expression and poor overall survival in multiple cancers. In toto, our work demonstrates that RAD52 contributes to the maintenance of genome stability and tumor suppression in human cells.
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Affiliation(s)
- Yinan Kan
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota Medical School, Minneapolis, MN 55455, United States
| | - Nizar N Batada
- Department of Medical Biophysics, University of Toronto, Toronto, Canada
| | - Eric A Hendrickson
- BMBB Department, University of Minnesota Medical School, 6-155 Jackson Hall, 321 Church St., SE., Minneapolis, MN 55455, United States.
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160
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Control of gene editing by manipulation of DNA repair mechanisms. Mamm Genome 2017; 28:262-274. [DOI: 10.1007/s00335-017-9688-5] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Accepted: 03/25/2017] [Indexed: 12/22/2022]
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161
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Mayca Pozo F, Tang J, Bonk KW, Keri RA, Yao X, Zhang Y. Regulatory cross-talk determines the cellular levels of 53BP1 protein, a critical factor in DNA repair. J Biol Chem 2017; 292:5992-6003. [PMID: 28255090 DOI: 10.1074/jbc.m116.760645] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Revised: 02/28/2017] [Indexed: 01/08/2023] Open
Abstract
DNA double strand breaks (DSBs) severely disrupt DNA integrity. 53BP1 plays critical roles in determining DSB repair. Whereas the recruitment of 53BP1 to the DSB site is key for its function, recent evidence suggests that 53BP1's abundance also plays an important role in DSB repair because recruitment to damage sites will be influenced by protein availability. Initial evidence has pointed to three proteins, the ubiquitin-conjugating enzyme UbcH7, the cysteine protease cathepsin L (CTSL), and the nuclear structure protein lamin A/C, that may impact 53BP1 levels, but the roles of each protein and any interplay between them were unclear. Here we report that UbcH7-dependent degradation plays a major role in controlling 53BP1 levels both under normal growth conditions and during DNA damage. CTSL influenced 53BP1 degradation during DNA damage while having little effect under normal growth conditions. Interestingly, both the protein and the mRNA levels of CTSL were reduced in UbcH7-depleted cells. Lamin A/C interacted with 53BP1 under normal conditions. DNA damage disrupted the lamin A/C-53BP1 interaction, which preceded the degradation of 53BP1 in soluble, but not chromatin-enriched, cellular fractions. Inhibition of 53BP1 degradation by a proteasome inhibitor or by UbcH7 depletion restored the 53BP1-lamin A/C interaction. Depletion of lamin A/C, but not CTSL, caused a similar enhancement in cell sensitivity to DNA damage as UbcH7 depletion. These data suggest that multiple pathways collectively fine-tune the cellular levels of 53BP1 protein to ensure proper DSB repair and cell survival.
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Affiliation(s)
- Franklin Mayca Pozo
- From the Department of Pharmacology, Case Comprehensive Cancer Center, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106 and
| | - Jinshan Tang
- From the Department of Pharmacology, Case Comprehensive Cancer Center, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106 and.,Institute of Traditional Chinese Medicine and Natural Products, College of Pharmacy, Jinan University, Guangzhou 510632, China
| | - Kristen W Bonk
- From the Department of Pharmacology, Case Comprehensive Cancer Center, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106 and
| | - Ruth A Keri
- From the Department of Pharmacology, Case Comprehensive Cancer Center, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106 and
| | - Xinsheng Yao
- Institute of Traditional Chinese Medicine and Natural Products, College of Pharmacy, Jinan University, Guangzhou 510632, China
| | - Youwei Zhang
- From the Department of Pharmacology, Case Comprehensive Cancer Center, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106 and
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162
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Nepomuceno TC, Fernandes VC, Gomes TT, Carvalho RS, Suarez-Kurtz G, Monteiro AN, Carvalho MA. BRCA1 recruitment to damaged DNA sites is dependent on CDK9. Cell Cycle 2017; 16:665-672. [PMID: 28278048 DOI: 10.1080/15384101.2017.1295177] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Double strand break lesions, the most toxic type of DNA damage, are repaired primarily through 2 distinct pathways: homology-directed recombination (HR) and non-homologous end-joining (NHEJ). BRCA1 and 53BP1, 2 proteins containing the BRCT modular domain, play an important role in DNA damage response (DDR) by orchestrating the decision between HR and NHEJ, but the precise mechanisms regarding both pathways are not entirely understood. Previously, our group identified a putative interaction between BRCA1 and BARD1 (BRCA1-associated RING domain 1) and the cyclin-dependent kinase (CDK9). CDK9 is a component of the positive transcription elongation complex and has been implicated in genome integrity maintenance associated with the replication stress response. Here we show that CDK9 interacts with endogenous BRCA1 and BARD1 mediated by their RING finger and BRCT domains, and describe CDK9 ionizing radiation-induced foci (IRIF) formation and its co-localization with BRCA1 in DNA damage sites. Cells lacking CDK9 are characterized by an altered γ-H2AX foci dynamics after DNA damage, a reduced efficiency in HR but not in NHEJ repair, failure to form BRCA1 and RAD51 IRIF and increased sensitivity to genotoxic agents. These data indicate that CDK9 is a player in the DDR and is consistent with its participation in HR pathway by modulating BRCA1 response.
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Affiliation(s)
- Thales C Nepomuceno
- a Programa de Pesquisa Clínica , Instituto Nacional de Câncer , Rio de Janeiro , Brazil
| | - Vanessa C Fernandes
- a Programa de Pesquisa Clínica , Instituto Nacional de Câncer , Rio de Janeiro , Brazil
| | - Thiago T Gomes
- b Instituto Federal do Rio de Janeiro - IFRJ , Rio de Janeiro , Brazil
| | - Renato S Carvalho
- c Faculdade de Farmácia - Universidade Federal do Rio de Janeiro , Rio de Janeiro , RJ , Brazil
| | | | - Alvaro N Monteiro
- d Cancer Epidemiology Program , H. Lee Moffitt Cancer Center & Research Institute , Tampa , FL , USA
| | - Marcelo A Carvalho
- a Programa de Pesquisa Clínica , Instituto Nacional de Câncer , Rio de Janeiro , Brazil.,b Instituto Federal do Rio de Janeiro - IFRJ , Rio de Janeiro , Brazil
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163
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Abstract
Aging is characterized by a cumulative loss of genome integrity, which involves chromatin reorganization, transcriptional dysregulation and the accumulation of DNA damage. Sirtuins participate in the protection against these aging processes by promoting genome homeostasis in response to cellular stress. We recently reported that SirT7−/− mice suffer from partial embryonic lethality and a progeroid like phenotype. At the cellular level, SIRT7 depletion results in the impaired repair of DNA double-strand breaks (DSBs), one the most dangerous DNA lesions, leading to genome instability. SIRT7 is recruited to DSBs, where it specifically deacetylates histone H3 at lysine 18 and affects the focal accumulation of the DNA damage response factor 53BP1, thus influencing the efficiency of repair. Here, we integrate our findings with the current knowledge on the mode of action of other sirtuin family members in DNA repair. We emphasize their capacity to regulate chromatin structure as a response to DNA damage within the constraints imposed by cellular status.
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Affiliation(s)
- Berta N Vazquez
- a Rutgers University, Department of Genetics , Human Genetics Institute of New Jersey , Piscataway , NJ , USA
| | - Joshua K Thackray
- a Rutgers University, Department of Genetics , Human Genetics Institute of New Jersey , Piscataway , NJ , USA
| | - Lourdes Serrano
- a Rutgers University, Department of Genetics , Human Genetics Institute of New Jersey , Piscataway , NJ , USA
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164
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HSP90 inhibition sensitizes head and neck cancer to platin-based chemoradiotherapy by modulation of the DNA damage response resulting in chromosomal fragmentation. BMC Cancer 2017; 17:86. [PMID: 28143445 PMCID: PMC5282703 DOI: 10.1186/s12885-017-3084-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2016] [Accepted: 01/23/2017] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND Concurrent cisplatin radiotherapy (CCRT) is a current standard-of-care for locally advanced head and neck squamous cell carcinoma (HNSCC). However, CCRT is frequently ineffective in patients with advanced disease. It has previously been shown that HSP90 inhibitors act as radiosensitizers, but these studies have not focused on CCRT in HNSCC. Here, we evaluated the HSP90 inhibitor, AUY922, combined with CCRT. METHODS The ability of AUY922 to sensitize to CCRT was assessed in p53 mutant head and neck cell lines by clonogenic assay. Modulation of the CCRT induced DNA damage response (DDR) by AUY922 was characterized by confocal image analysis of RAD51, BRCA1, 53BP1, ATM and mutant p53 signaling. The role of FANCA depletion by AUY922 was examined using shRNA. Cell cycle checkpoint abrogation and chromosomal fragmentation was assessed by western blot, FACS and confocal. The role of ATM was also assessed by shRNA. AUY922 in combination with CCRT was assessed in vivo. RESULTS The combination of AUY922 with cisplatin, radiation and CCRT was found to be synergistic in p53 mutant HNSCC. AUY922 leads to significant alterations to the DDR induced by CCRT. This comprises inhibition of homologous recombination through decreased RAD51 and pS1524 BRCA1 with a corresponding increase in 53BP1 foci, activation of ATM and signaling into mutant p53. A shift to more error prone repair combined with a loss of checkpoint function leads to fragmentation of chromosomal material. The degree of disruption to DDR signalling correlated to chromosomal fragmentation and loss of clonogenicity. ATM shRNA indicated a possible rationale for the combination of AUY922 and CCRT in cells lacking ATM function. CONCLUSIONS This study supports future clinical studies combining AUY922 and CCRT in p53 mutant HNSCC. Modulation of the DDR and chromosomal fragmentation are likely to be analytical points of interest in such trials.
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165
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MCL-1 Depletion Impairs DNA Double-Strand Break Repair and Reinitiation of Stalled DNA Replication Forks. Mol Cell Biol 2017; 37:MCB.00535-16. [PMID: 27821478 DOI: 10.1128/mcb.00535-16] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Accepted: 10/24/2016] [Indexed: 12/31/2022] Open
Abstract
Myeloid cell leukemia 1 (MCL-1) is a prosurvival BCL-2 protein family member highly expressed in hematopoietic stem cells (HSCs) and regulated by growth factor signals that manifest antiapoptotic activity. Here we report that depletion of MCL-1 but not its isoform MCL-1S increases genomic instability and cell sensitivity to ionizing radiation (IR)-induced death. MCL-1 association with genomic DNA increased postirradiation, and the protein colocalized with 53BP1 foci. Postirradiation, MCL-1-depleted cells exhibited decreased γ-H2AX foci, decreased phosphorylation of ATR, and higher levels of residual 53BP1 and RIF1 foci, suggesting that DNA double-strand break (DSB) repair by homologous recombination (HR) was compromised. Consistent with this model, MCL-1-depleted cells had a reduced frequency of IR-induced BRCA1, RPA, and Rad51 focus formation, decreased DNA end resection, and decreased HR repair in the DR-GFP DSB repair model. Similarly, after HU induction of stalled replication forks in MCL-1-depleted cells, there was a decreased ability to subsequently restart DNA synthesis, which is normally dependent upon HR-mediated resolution of collapsed forks. Therefore, the present data support a model whereby MCL-1 depletion increases 53BP1 and RIF1 colocalization at DSBs, which inhibits BRCA1 recruitment, and sensitizes cells to DSBs from IR or stalled replication forks that require HR for repair.
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Mackay DR, Howa AC, Werner TL, Ullman KS. Nup153 and Nup50 promote recruitment of 53BP1 to DNA repair foci by antagonizing BRCA1-dependent events. J Cell Sci 2017; 130:3347-3359. [DOI: 10.1242/jcs.203513] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Accepted: 07/24/2017] [Indexed: 12/28/2022] Open
Abstract
DNA double strand breaks are typically repaired through either the high-fidelity process of homologous recombination (HR), in which BRCA1 plays a key role, or the more error-prone process of non-homologous end joining (NHEJ), which relies on 53BP1. The balance between NHEJ and HR depends, in part, on whether 53BP1 predominates in binding to damage sites, where it protects the DNA ends from resection. The nucleoporin Nup153 has been implicated in the DNA damage response, attributed to a role in promoting nuclear import of 53BP1. Here, we define a distinct requirement for Nup153 in 53BP1 intranuclear targeting to damage foci and report that Nup153 likely facilitates the role of another nucleoporin, Nup50, in 53BP1 targeting. The requirement for Nup153 and Nup50 in promoting 53BP1 recruitment to damage foci induced by either etoposide or olaparib is abrogated in cells deficient for BRCA1 or its partner BARD1, but not in cells deficient for BRCA2. Together, our results further highlight the antagonistic relationship between 53BP1 and BRCA1 and place Nup153 and Nup50 in a molecular pathway that regulates 53BP1 function by counteracting BRCA1-mediated events.
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Affiliation(s)
- Douglas R. Mackay
- Department of Oncological Sciences, Huntsman Cancer Institute, University of Utah, Salt Lake City, UT 84112, USA
| | - Amanda C. Howa
- Department of Oncological Sciences, Huntsman Cancer Institute, University of Utah, Salt Lake City, UT 84112, USA
| | - Theresa L. Werner
- Department of Oncology, Huntsman Cancer Institute, University of Utah, Salt Lake City, UT 84112, USA
| | - Katharine S. Ullman
- Department of Oncological Sciences, Huntsman Cancer Institute, University of Utah, Salt Lake City, UT 84112, USA
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167
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Pathway swapping: Toward modular engineering of essential cellular processes. Proc Natl Acad Sci U S A 2016; 113:15060-15065. [PMID: 27956602 DOI: 10.1073/pnas.1606701113] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Recent developments in synthetic biology enable one-step implementation of entire metabolic pathways in industrial microorganisms. A similarly radical remodelling of central metabolism could greatly accelerate fundamental and applied research, but is impeded by the mosaic organization of microbial genomes. To eliminate this limitation, we propose and explore the concept of "pathway swapping," using yeast glycolysis as the experimental model. Construction of a "single-locus glycolysis" Saccharomyces cerevisiae platform enabled quick and easy replacement of this yeast's entire complement of 26 glycolytic isoenzymes by any alternative, functional glycolytic pathway configuration. The potential of this approach was demonstrated by the construction and characterization of S. cerevisiae strains whose growth depended on two nonnative glycolytic pathways: a complete glycolysis from the related yeast Saccharomyces kudriavzevii and a mosaic glycolysis consisting of yeast and human enzymes. This work demonstrates the feasibility and potential of modular, combinatorial approaches to engineering and analysis of core cellular processes.
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168
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Lawrence KS, Tapley EC, Cruz VE, Li Q, Aung K, Hart KC, Schwartz TU, Starr DA, Engebrecht J. LINC complexes promote homologous recombination in part through inhibition of nonhomologous end joining. J Cell Biol 2016; 215:801-821. [PMID: 27956467 PMCID: PMC5166498 DOI: 10.1083/jcb.201604112] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Revised: 09/03/2016] [Accepted: 10/31/2016] [Indexed: 01/23/2023] Open
Abstract
The Caenorhabditis elegans SUN domain protein, UNC-84, functions in nuclear migration and anchorage in the soma. We discovered a novel role for UNC-84 in DNA damage repair and meiotic recombination. Loss of UNC-84 leads to defects in the loading and disassembly of the recombinase RAD-51. Similar to mutations in Fanconi anemia (FA) genes, unc-84 mutants and human cells depleted of Sun-1 are sensitive to DNA cross-linking agents, and sensitivity is rescued by the inactivation of nonhomologous end joining (NHEJ). UNC-84 also recruits FA nuclease FAN-1 to the nucleoplasm, suggesting that UNC-84 both alters the extent of repair by NHEJ and promotes the processing of cross-links by FAN-1. UNC-84 interacts with the KASH protein ZYG-12 for DNA damage repair. Furthermore, the microtubule network and interaction with the nucleoskeleton are important for repair, suggesting that a functional linker of nucleoskeleton and cytoskeleton (LINC) complex is required. We propose that LINC complexes serve a conserved role in DNA repair through both the inhibition of NHEJ and the promotion of homologous recombination at sites of chromosomal breaks.
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Affiliation(s)
- Katherine S Lawrence
- Department of Molecular and Cellular Biology; Biochemistry, Molecular Cellular, and Developmental Biology Graduate Group, University of California, Davis, Davis, CA 95616
| | - Erin C Tapley
- Department of Molecular and Cellular Biology; Biochemistry, Molecular Cellular, and Developmental Biology Graduate Group, University of California, Davis, Davis, CA 95616
| | - Victor E Cruz
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Qianyan Li
- Department of Molecular and Cellular Biology; Biochemistry, Molecular Cellular, and Developmental Biology Graduate Group, University of California, Davis, Davis, CA 95616
| | - Kayla Aung
- Department of Molecular and Cellular Biology; Biochemistry, Molecular Cellular, and Developmental Biology Graduate Group, University of California, Davis, Davis, CA 95616
| | - Kevin C Hart
- Department of Molecular and Cellular Biology; Biochemistry, Molecular Cellular, and Developmental Biology Graduate Group, University of California, Davis, Davis, CA 95616
| | - Thomas U Schwartz
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Daniel A Starr
- Department of Molecular and Cellular Biology; Biochemistry, Molecular Cellular, and Developmental Biology Graduate Group, University of California, Davis, Davis, CA 95616
| | - JoAnne Engebrecht
- Department of Molecular and Cellular Biology; Biochemistry, Molecular Cellular, and Developmental Biology Graduate Group, University of California, Davis, Davis, CA 95616
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169
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Chroma K, Mistrik M, Moudry P, Gursky J, Liptay M, Strauss R, Skrott Z, Vrtel R, Bartkova J, Kramara J, Bartek J. Tumors overexpressing RNF168 show altered DNA repair and responses to genotoxic treatments, genomic instability and resistance to proteotoxic stress. Oncogene 2016; 36:2405-2422. [DOI: 10.1038/onc.2016.392] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Revised: 08/14/2016] [Accepted: 09/12/2016] [Indexed: 12/20/2022]
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170
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Coucoravas C, Dhanjal S, Henriksson S, Böhm S, Farnebo M. Phosphorylation of the Cajal body protein WRAP53β by ATM promotes its involvement in the DNA damage response. RNA Biol 2016; 14:804-813. [PMID: 27715493 PMCID: PMC5519231 DOI: 10.1080/15476286.2016.1243647] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The cellular response to DNA double-strand breaks is orchestrated by the protein kinase ATM, which phosphorylates key actors in the DNA repair network. WRAP53β is a multifunctional protein that controls trafficking of factors to Cajal bodies, telomeres and DNA double-strand breaks but what regulates the involvement of WRAP53β in these separate processes remains unclear. Here, we show that in response to various types of DNA damage, including IR and UV, WRAP53β is phosphorylated on serine residue 64 by ATM with a time-course that parallels its accumulation at DNA lesions. Interestingly, recruitment of phosphorylated WRAP53β (pWRAP53βS64) to sites of such DNA damage promotes its interaction with γH2AX at these locations. Moreover, pWRAP53βS64 stimulates the accumulation of the repair factor 53BP1 at DNA double-strand breaks and enhances repair of this type of damage via homologous recombination and non-homologous end joining. At the same time, phosphorylation of WRAP53β is dispensable for its localization to Cajal bodies, where it accumulates even in unstressed cells. These findings not only reveal ATM to be an upstream regulator of WRAP53β, but also indicates that phosphorylation of WRAP53β at serine 64 controls its involvement in the DNA damage response and may also restrict its other functions.
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Affiliation(s)
- Christos Coucoravas
- a Department of Oncology-Pathology , Cancer Centrum Karolinska (CCK), Karolinska Institutet , Stockholm , Sweden
| | - Soniya Dhanjal
- a Department of Oncology-Pathology , Cancer Centrum Karolinska (CCK), Karolinska Institutet , Stockholm , Sweden
| | - Sofia Henriksson
- a Department of Oncology-Pathology , Cancer Centrum Karolinska (CCK), Karolinska Institutet , Stockholm , Sweden
| | - Stefanie Böhm
- a Department of Oncology-Pathology , Cancer Centrum Karolinska (CCK), Karolinska Institutet , Stockholm , Sweden
| | - Marianne Farnebo
- a Department of Oncology-Pathology , Cancer Centrum Karolinska (CCK), Karolinska Institutet , Stockholm , Sweden
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Chakraborty A, Tapryal N, Venkova T, Horikoshi N, Pandita RK, Sarker AH, Sarkar PS, Pandita TK, Hazra TK. Classical non-homologous end-joining pathway utilizes nascent RNA for error-free double-strand break repair of transcribed genes. Nat Commun 2016; 7:13049. [PMID: 27703167 PMCID: PMC5059474 DOI: 10.1038/ncomms13049] [Citation(s) in RCA: 121] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Accepted: 08/30/2016] [Indexed: 12/30/2022] Open
Abstract
DNA double-strand breaks (DSBs) leading to loss of nucleotides in the transcribed region can be lethal. Classical non-homologous end-joining (C-NHEJ) is the dominant pathway for DSB repair (DSBR) in adult mammalian cells. Here we report that during such DSBR, mammalian C-NHEJ proteins form a multiprotein complex with RNA polymerase II and preferentially associate with the transcribed genes after DSB induction. Depletion of C-NHEJ factors significantly abrogates DSBR in transcribed but not in non-transcribed genes. We hypothesized that nascent RNA can serve as a template for restoring the missing sequences, thus allowing error-free DSBR. We indeed found pre-mRNA in the C-NHEJ complex. Finally, when a DSB-containing plasmid with several nucleotides deleted within the E. coli lacZ gene was allowed time to repair in lacZ-expressing mammalian cells, a functional lacZ plasmid could be recovered from control but not C-NHEJ factor-depleted cells, providing important mechanistic insights into C-NHEJ-mediated error-free DSBR of the transcribed genome. Most adult mammalian cells prefer to repair double-strand DNA breaks though the classical nonhomologous end-joining pathway. Here the authors present evidence that a nascent RNA transcript can serve as a template to facilitate error-free repair.
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Affiliation(s)
- Anirban Chakraborty
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Sealy Center for Molecular Medicine, University of Texas Medical Branch, Galveston, Texas 77555, USA
| | - Nisha Tapryal
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Sealy Center for Molecular Medicine, University of Texas Medical Branch, Galveston, Texas 77555, USA
| | - Tatiana Venkova
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Sealy Center for Molecular Medicine, University of Texas Medical Branch, Galveston, Texas 77555, USA
| | - Nobuo Horikoshi
- Department of Radiation Oncology, The Houston Methodist Research Institute, Houston, Texas 77030, USA
| | - Raj K Pandita
- Department of Radiation Oncology, The Houston Methodist Research Institute, Houston, Texas 77030, USA
| | - Altaf H Sarker
- Division of Life Sciences, Department of Cancer and DNA Damage Responses, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Partha S Sarkar
- Department of Neurology and Neuroscience and Cell Biology, University of Texas Medical Branch, Galveston, Texas 77555, USA
| | - Tej K Pandita
- Department of Radiation Oncology, The Houston Methodist Research Institute, Houston, Texas 77030, USA
| | - Tapas K Hazra
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Sealy Center for Molecular Medicine, University of Texas Medical Branch, Galveston, Texas 77555, USA
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172
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Tóth E, Weinhardt N, Bencsura P, Huszár K, Kulcsár PI, Tálas A, Fodor E, Welker E. Cpf1 nucleases demonstrate robust activity to induce DNA modification by exploiting homology directed repair pathways in mammalian cells. Biol Direct 2016; 11:46. [PMID: 27630115 PMCID: PMC5024423 DOI: 10.1186/s13062-016-0147-0] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Accepted: 08/31/2016] [Indexed: 12/26/2022] Open
Abstract
Background Cpf1 nucleases have recently been repurposed for site-specific genome modification. Two members of the Cpf1 family, the AsCpf1 from Acidaminococcus sp. and the LbCpf1 from Lachnospiraceae bacterium were shown to induce higher indel frequencies than SpCas9 when examining four randomly-selected target sequences for each type of nuclease. Whether they are a real match for Cas9 nucleases, however, remains to be verified. Results Here, we used AsCpf1 and LbCpf1 to induce homology directed repair, either single strand annealing (SSA) or homologous recombination (HR), in N2a mouse neuroblastoma cells. Exploiting a plasmid that contains two GFP halves with overlapping sequences and exploring 20 targets, on all but one both nucleases consistently performed with above 10 % efficiency. Several Cas9 nucleases have been previously characterised in order to find an orthogonal counterpart for the most widely used promiscuous SpCas9. Here, we found that AsCpf1 and LbCpf1 might be better candidates than three of the best such counterparts: Cas9 from Staphylococcus aureus, from Streptococcus thermophilus and from Neisseria meningitidis, when assessed for inducing efficient SSA mediated repair in N2a cells. When tested on genomic targets exploiting HR, both nucleases were able to induce the integration of a donor cassette with 1000 bp-long homologous arms. We also generated plasmids that express these Cpf1 nucleases together with their cognate crRNAs and that are equipped with type IIS restriction enzyme sites to facilitate spacer cloning. Conclusions Our results suggest that employing As- or LbCpf1 nuclease to induce homology directed repair in N2a cells, although is less effective at present than employing SpCas9, it is an equally or more effective tool than the most frequently used orthogonal Cas9 counterparts of SpCas9. These findings support the position of Cpf1 nucleases on the side of SpCas9 on the palette of effective genome engineering tools. Reviewers This article was reviewed by Eugene Koonin, Haruhiko Siomi and Jean-Yves Masson. Electronic supplementary material The online version of this article (doi:10.1186/s13062-016-0147-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Eszter Tóth
- Institute of Enzymology, Research Centre for Natural Sciences of the Hungarian Academy of Sciences, 2 Magyar Tudósok krt., Budapest, H-1117, Hungary.,Institute of Biochemistry, Biological Research Centre, Hungarian Academy of Sciences, Szeged, H-6726, Hungary
| | - Nóra Weinhardt
- Institute of Enzymology, Research Centre for Natural Sciences of the Hungarian Academy of Sciences, 2 Magyar Tudósok krt., Budapest, H-1117, Hungary.,Institute of Biochemistry, Biological Research Centre, Hungarian Academy of Sciences, Szeged, H-6726, Hungary.,University of Szeged, Szeged, H-6726, Hungary
| | - Petra Bencsura
- Institute of Enzymology, Research Centre for Natural Sciences of the Hungarian Academy of Sciences, 2 Magyar Tudósok krt., Budapest, H-1117, Hungary
| | - Krisztina Huszár
- Institute of Enzymology, Research Centre for Natural Sciences of the Hungarian Academy of Sciences, 2 Magyar Tudósok krt., Budapest, H-1117, Hungary.,Institute of Biochemistry, Biological Research Centre, Hungarian Academy of Sciences, Szeged, H-6726, Hungary
| | - Péter I Kulcsár
- Institute of Enzymology, Research Centre for Natural Sciences of the Hungarian Academy of Sciences, 2 Magyar Tudósok krt., Budapest, H-1117, Hungary.,Institute of Biochemistry, Biological Research Centre, Hungarian Academy of Sciences, Szeged, H-6726, Hungary.,University of Szeged, Szeged, H-6726, Hungary
| | - András Tálas
- Institute of Enzymology, Research Centre for Natural Sciences of the Hungarian Academy of Sciences, 2 Magyar Tudósok krt., Budapest, H-1117, Hungary.,Semmelweis University, Budapest, H-1085, Hungary
| | - Elfrieda Fodor
- Institute of Biochemistry, Biological Research Centre, Hungarian Academy of Sciences, Szeged, H-6726, Hungary
| | - Ervin Welker
- Institute of Enzymology, Research Centre for Natural Sciences of the Hungarian Academy of Sciences, 2 Magyar Tudósok krt., Budapest, H-1117, Hungary. .,Institute of Biochemistry, Biological Research Centre, Hungarian Academy of Sciences, Szeged, H-6726, Hungary.
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173
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In vivo genome editing as a potential treatment strategy for inherited retinal dystrophies. Prog Retin Eye Res 2016; 56:1-18. [PMID: 27623223 DOI: 10.1016/j.preteyeres.2016.09.001] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Revised: 09/06/2016] [Accepted: 09/08/2016] [Indexed: 12/20/2022]
Abstract
In vivo genome editing represents an emerging field in the treatment of monogenic disorders, as it may constitute a solution to the current hurdles in classic gene addition therapy, which are the low levels and limited duration of transgene expression. Following the introduction of a double strand break (DSB) at the mutational site by highly specific endonucleases, such as TALENs (transcription activator like effector nucleases) or RNA based nucleases (clustered regulatory interspaced short palindromic repeats - CRISPR-Cas), the cell's own DNA repair machinery restores integrity to the DNA strand and corrects the mutant sequence, thus allowing the cell to produce protein levels as needed. The DNA repair happens either through the error prone non-homologous end-joining (NHEJ) pathway or with high fidelity through homology directed repair (HDR) in the presence of a DNA donor template. A third pathway called microhomology mediated endjoining (MMEJ) has been recently discovered. In this review, the authors focus on the different DNA repair mechanisms, the current state of the art tools for genome editing and the particularities of the retina and photoreceptors with regard to in vivo therapeutic approaches. Finally, current attempts in the field of retinal in vivo genome editing are discussed and future directions of research identified.
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174
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Hong R, Ma F, Zhang W, Yu X, Li Q, Luo Y, Zhu C, Jiang W, Xu B. 53BP1 depletion causes PARP inhibitor resistance in ATM-deficient breast cancer cells. BMC Cancer 2016; 16:725. [PMID: 27613518 PMCID: PMC5017014 DOI: 10.1186/s12885-016-2754-7] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2016] [Accepted: 08/28/2016] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Mutations in DNA damage response factors BRCA1 and BRCA2 confer sensitivity to poly(ADP-ribose) polymerase (PARP) inhibitors in breast and ovarian cancers. BRCA1/BRCA2-defective tumors can exhibit resistance to PARP inhibitors via multiple mechanisms, one of which involves loss of 53BP1. Deficiency in the DNA damage response factor ataxia-telangiectasia mutated (ATM) can also sensitize tumors to PARP inhibitors, raising the question of whether the presence or absence of 53BP1 can predict sensitivity of ATM-deficient breast cancer to these inhibitors. METHODS Cytotoxicity of PARP inhibitor and ATM inhibitor in breast cancer cell lines was assessed by MTS, colony formation and apoptosis assays. ShRNA lentiviral vectors were used to knockdown 53BP1 expression in breast cancer cell lines. Phospho-ATM and 53BP1 protein expressions were determined in human breast cancer tissues by immunohistochemistry (IHC). RESULTS We show that inhibiting ATM increased cytotoxicity of PARP inhibitor in triple-negative and non-triple-negative breast cancer cell lines, and depleting the cells of 53BP1 reduced this cytotoxicity. Inhibiting ATM abrogated homologous recombination induced by PARP inhibitor, and down-regulating 53BP1 partially reversed this effect. Further, overall survival was significantly better in triple-negative breast cancer patients with lower levels of phospho-ATM and tended to be better in patients with negative 53BP1. CONCLUSION These results suggest that 53BP1 may be a predictor of PARP inhibitor resistance in patients with ATM-deficient tumors.
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Affiliation(s)
- Ruoxi Hong
- Department of Medical Oncology, Cancer Institute and Hospital, Peking Union Medical College and Chinese Academy of Medical Sciences, Beijing, China.,Department of Medical Oncology, Sun Yat-sen University Cancer Center, Guangzhou, China
| | - Fei Ma
- Department of Medical Oncology, Cancer Institute and Hospital, Peking Union Medical College and Chinese Academy of Medical Sciences, Beijing, China
| | - Weimin Zhang
- State Key Laboratory of Molecular Oncology, Cancer Institute and Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Xiying Yu
- State Key Laboratory of Molecular Oncology, Cancer Institute and Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Qing Li
- Department of Medical Oncology, Cancer Institute and Hospital, Peking Union Medical College and Chinese Academy of Medical Sciences, Beijing, China
| | - Yang Luo
- Department of Medical Oncology, Cancer Institute and Hospital, Peking Union Medical College and Chinese Academy of Medical Sciences, Beijing, China
| | - Changjun Zhu
- College of Life Science/Tianjin Key Laboratory of Cyto-Genetical and Molecular Regulation, Tianjin Normal University, Tianjin, 300387, China
| | - Wei Jiang
- State Key Laboratory of Molecular Oncology, Cancer Institute and Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.
| | - Binghe Xu
- Department of Medical Oncology, Cancer Institute and Hospital, Peking Union Medical College and Chinese Academy of Medical Sciences, Beijing, China.
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175
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Ng HM, Wei L, Lan L, Huen MSY. The Lys63-deubiquitylating Enzyme BRCC36 Limits DNA Break Processing and Repair. J Biol Chem 2016; 291:16197-207. [PMID: 27288411 DOI: 10.1074/jbc.m116.731927] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Indexed: 12/31/2022] Open
Abstract
Multisubunit protein assemblies offer integrated functionalities for efficient cell signal transduction control. One example of such protein assemblies, the BRCA1-A macromolecular complex, couples ubiquitin recognition and metabolism and promotes cellular responses to DNA damage. Specifically, the BRCA1-A complex not only recognizes Lys(63)-linked ubiquitin (K63-Ub) adducts at the damaged chromatin but is endowed with K63-Ub deubiquitylase (DUB) activity. To explore how the BRCA1-A DUB activity contributes to its function at DNA double strand breaks (DSBs), we used RNAi and genome editing approaches to target BRCC36, the protein subunit that confers the BRCA1-A complex its DUB activity. Intriguingly, we found that the K63-Ub DUB activity, although dispensable for maintaining the integrity of the macromolecular protein assembly, is important in enforcing the accumulation of the BRCA1-A complex onto DSBs. Inactivating BRCC36 DUB attenuated BRCA1-A functions at DSBs and led to unrestrained DSB end resection and hyperactive DNA repair. Together, our findings uncover a pivotal role of BRCC36 DUB in limiting DSB processing and repair and illustrate how cells may physically couple ubiquitin recognition and metabolizing activities for fine tuning of DNA repair processes.
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Affiliation(s)
- Hoi-Man Ng
- From the School of Biomedical Sciences, LKS Faculty of Medicine, and
| | - Leizhen Wei
- the Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15213
| | - Li Lan
- the Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15213
| | - Michael S Y Huen
- From the School of Biomedical Sciences, LKS Faculty of Medicine, and the State Key Laboratory of Brain and Cognitive Sciences, University of Hong Kong, L1-46, Laboratory Block, 21 Sassoon Road, Pokfulam, Hong Kong and
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176
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González F. CRISPR/Cas9 genome editing in human pluripotent stem cells: Harnessing human genetics in a dish. Dev Dyn 2016; 245:788-806. [DOI: 10.1002/dvdy.24414] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Revised: 05/02/2016] [Accepted: 05/02/2016] [Indexed: 12/14/2022] Open
Affiliation(s)
- Federico González
- Institute for Bioengineering of Catalonia (IBEC); Calle Baldiri Reixac 15-21 08028 Barcelona Spain
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Penterling C, Drexler GA, Böhland C, Stamp R, Wilke C, Braselmann H, Caldwell RB, Reindl J, Girst S, Greubel C, Siebenwirth C, Mansour WY, Borgmann K, Dollinger G, Unger K, Friedl AA. Depletion of Histone Demethylase Jarid1A Resulting in Histone Hyperacetylation and Radiation Sensitivity Does Not Affect DNA Double-Strand Break Repair. PLoS One 2016; 11:e0156599. [PMID: 27253695 PMCID: PMC4890786 DOI: 10.1371/journal.pone.0156599] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Accepted: 05/17/2016] [Indexed: 12/31/2022] Open
Abstract
Histone demethylases have recently gained interest as potential targets in cancer treatment and several histone demethylases have been implicated in the DNA damage response. We investigated the effects of siRNA-mediated depletion of histone demethylase Jarid1A (KDM5A, RBP2), which demethylates transcription activating tri- and dimethylated lysine 4 at histone H3 (H3K4me3/me2), on growth characteristics and cellular response to radiation in several cancer cell lines. In unirradiated cells Jarid1A depletion lead to histone hyperacetylation while not affecting cell growth. In irradiated cells, depletion of Jarid1A significantly increased cellular radiosensitivity. Unexpectedly, the hyperacetylation phenotype did not lead to disturbed accumulation of DNA damage response and repair factors 53BP1, BRCA1, or Rad51 at damage sites, nor did it influence resolution of radiation-induced foci or rejoining of reporter constructs. We conclude that the radiation sensitivity observed following depletion of Jarid1A is not caused by a deficiency in repair of DNA double-strand breaks.
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Affiliation(s)
- Corina Penterling
- Department of Radiation Oncology, Ludwig-Maximilians-University of Munich, Munich, Germany
| | - Guido A. Drexler
- Department of Radiation Oncology, Ludwig-Maximilians-University of Munich, Munich, Germany
| | - Claudia Böhland
- Department of Radiation Oncology, Ludwig-Maximilians-University of Munich, Munich, Germany
| | - Ramona Stamp
- Department of Radiation Oncology, Ludwig-Maximilians-University of Munich, Munich, Germany
| | - Christina Wilke
- Research Unit Radiation Cytogenetics, Helmholtz Center Munich, Neuherberg, Germany
| | - Herbert Braselmann
- Research Unit Radiation Cytogenetics, Helmholtz Center Munich, Neuherberg, Germany
| | - Randolph B. Caldwell
- Research Unit Radiation Cytogenetics, Helmholtz Center Munich, Neuherberg, Germany
| | - Judith Reindl
- Institut für Angewandte Physik und Messtechnik, Universität der Bundeswehr München, Neubiberg, Germany
| | - Stefanie Girst
- Institut für Angewandte Physik und Messtechnik, Universität der Bundeswehr München, Neubiberg, Germany
| | - Christoph Greubel
- Institut für Angewandte Physik und Messtechnik, Universität der Bundeswehr München, Neubiberg, Germany
| | | | - Wael Y. Mansour
- Laboratory of Radiobiology & Experimental Radiooncology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
- Tumor Biology Department, National Cancer Institute, Cairo University, Cairo, Egypt
| | - Kerstin Borgmann
- Laboratory of Radiobiology & Experimental Radiooncology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Günther Dollinger
- Institut für Angewandte Physik und Messtechnik, Universität der Bundeswehr München, Neubiberg, Germany
| | - Kristian Unger
- Research Unit Radiation Cytogenetics, Helmholtz Center Munich, Neuherberg, Germany
- Clinical Cooperation Group ‘Personalized Radiotherapy of Head and Neck Cancer’, Helmholtz Center Munich, Neuherberg, Germany
| | - Anna A. Friedl
- Department of Radiation Oncology, Ludwig-Maximilians-University of Munich, Munich, Germany
- Clinical Cooperation Group ‘Personalized Radiotherapy of Head and Neck Cancer’, Helmholtz Center Munich, Neuherberg, Germany
- * E-mail:
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178
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Fenoy IM, Bogado SS, Contreras SM, Gottifredi V, Angel SO. The Knowns Unknowns: Exploring the Homologous Recombination Repair Pathway in Toxoplasma gondii. Front Microbiol 2016; 7:627. [PMID: 27199954 PMCID: PMC4853372 DOI: 10.3389/fmicb.2016.00627] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Accepted: 04/18/2016] [Indexed: 12/17/2022] Open
Abstract
Toxoplasma gondii is an apicomplexan parasite of medical and veterinary importance which causes toxoplasmosis in humans. Great effort is currently being devoted toward the identification of novel drugs capable of targeting such illness. In this context, we believe that the thorough understanding of the life cycle of this model parasite will facilitate the identification of new druggable targets in T. gondii. It is important to exploit the available knowledge of pathways which could modulate the sensitivity of the parasite to DNA damaging agents. The homologous recombination repair (HRR) pathway may be of particular interest in this regard as its inactivation sensitizes other cellular models such as human cancer to targeted therapy. Herein we discuss the information available on T. gondii's HRR pathway from the perspective of its conservation with respect to yeast and humans. Special attention was devoted to BRCT domain-containing and end-resection associated proteins in T. gondii as in other experimental models such proteins have crucial roles in early/late steps or HRR and in the pathway choice for double strand break resolution. We conclude that T. gondii HRR pathway is a source of several lines of investigation that allow to to comprehend the extent of diversification of HRR in T. gondii. Such an effort will serve to determine if HRR could represent a potential targer for the treatment of toxoplasmosis.
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Affiliation(s)
- Ignacio M Fenoy
- Laboratorio de Parasitología Molecular, IIB-INTECH, CONICET-UNSAM Chascomús, Argentina
| | - Silvina S Bogado
- Laboratorio de Parasitología Molecular, IIB-INTECH, CONICET-UNSAM Chascomús, Argentina
| | - Susana M Contreras
- Laboratorio de Parasitología Molecular, IIB-INTECH, CONICET-UNSAM Chascomús, Argentina
| | - Vanesa Gottifredi
- Cell Cycle Genomic Instability Laboratory, Fundación Instituto Leloir, IIBBA-CONICET Chascomús, Argentina
| | - Sergio O Angel
- Laboratorio de Parasitología Molecular, IIB-INTECH, CONICET-UNSAM Chascomús, Argentina
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179
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Yang W, Tu Z, Sun Q, Li XJ. CRISPR/Cas9: Implications for Modeling and Therapy of Neurodegenerative Diseases. Front Mol Neurosci 2016; 9:30. [PMID: 27199655 PMCID: PMC4848312 DOI: 10.3389/fnmol.2016.00030] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2016] [Accepted: 04/15/2016] [Indexed: 01/18/2023] Open
Abstract
CRISPR/Cas9 is now used widely to genetically modify the genomes of various species. The ability of CRISPR/Cas9 to delete DNA sequences and correct DNA mutations opens up a new avenue to treat genetic diseases that are caused by DNA mutations. In this review, we describe the advantages of using CRISPR/Cas9 to engineer genomic DNAs in animal embryos, as well as in specific regions or cell types in the brain. We also discuss how to apply CRISPR/Cas9 to establish animal models of neurodegenerative diseases, such as Parkinson’s and Huntington’s disease (HD), and to treat these disorders that are caused by genetic mutations.
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Affiliation(s)
- Weili Yang
- Institute of Genetics and Developmental Biology, Chinese Academy of Sciences Beijing, China
| | - Zhuchi Tu
- Institute of Genetics and Developmental Biology, Chinese Academy of Sciences Beijing, China
| | - Qiang Sun
- Institute of Genetics and Developmental Biology, Chinese Academy of Sciences Beijing, China
| | - Xiao-Jiang Li
- Institute of Genetics and Developmental Biology, Chinese Academy of SciencesBeijing, China; Department of Human Genetics, Emory University School of MedicineAtlanta, GA, USA
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180
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Seo Y, Tamari K, Yoshioka Y, Isohashi F, Suzuki O, Hayashi K, Takahashi Y, Baek S, Otani K, Ogawa K. Characterization of in vitro radiosensitization in mammalian cells using biomathematical modelling: implications for hypofractionated radiotherapy with a combined modality approach. Br J Radiol 2016; 89:20150724. [PMID: 26975496 DOI: 10.1259/bjr.20150724] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
OBJECTIVE It is unclear whether radiosensitization is beneficial when radiotherapy is administered at a high dose per fraction. The aim of this study was to assess the impact of radiation dose on the effectiveness of a broad range of radiosensitizers. METHODS We analyzed 653 pairs of clonogenic survival curves in 285 published articles, in which modifications of radiosensitivity were studied using the colony-forming assay. The modifications of radiosensitivity were arbitrarily classified into 20 classes. The survival curves were fitted to two biomathematical models: the linear-quadratic model and the repair-misrepair (RMR) model. RESULTS We found that radiosensitization was predominantly characterized by an increase of the α value (α-sensitization) without an increase of the β value (β-sensitization). A subset analysis revealed that all 20 classes showed significant α-sensitization. In contrast, only oxygen/hypoxic sensitizers (oxygen) and poly(adenosine diphosphate-ribose) polymerase inhibition (PARPi) exhibited β-sensitization. An analysis using the RMR model revealed two major sources of radiosensitization: an increased residual DNA lesion through repair inhibition and a shift from linear repairs to quadratic misrepairs, leading to enhanced lethal chromosomal aberrations. CONCLUSION Oxygen and PARPi were found to show β-sensitization, which was favourable for eliciting a comparable degree of sensitization in the higher dose range. Reduced fidelity of the repair was suggested to be a possible mechanism of β-sensitization. Further study targeting β-sensitization is needed to develop a novel combined modality therapy with high-dose-per-fraction radiotherapy. ADVANCES IN KNOWLEDGE Radiosensitization can be classified into two groups, α- and β-sensitizations. These two phenomena may stem from distinct underlying mechanisms.
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Affiliation(s)
- Yuji Seo
- Department of Radiation Oncology, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Keisuke Tamari
- Department of Radiation Oncology, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Yasuo Yoshioka
- Department of Radiation Oncology, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Fumiaki Isohashi
- Department of Radiation Oncology, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Osamu Suzuki
- Department of Radiation Oncology, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Kazuhiko Hayashi
- Department of Radiation Oncology, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Yutaka Takahashi
- Department of Radiation Oncology, Osaka University Graduate School of Medicine, Osaka, Japan
| | - SungJae Baek
- Department of Radiation Oncology, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Keisuke Otani
- Department of Radiation Oncology, Osaka University Graduate School of Medicine, Osaka, Japan
| | - Kazuhiko Ogawa
- Department of Radiation Oncology, Osaka University Graduate School of Medicine, Osaka, Japan
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181
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Nicolay NH, Rühle A, Perez RL, Trinh T, Sisombath S, Weber KJ, Schmezer P, Ho AD, Debus J, Saffrich R, Huber PE. Mesenchymal stem cells exhibit resistance to topoisomerase inhibition. Cancer Lett 2016; 374:75-84. [PMID: 26876302 DOI: 10.1016/j.canlet.2016.02.007] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2015] [Revised: 01/29/2016] [Accepted: 02/02/2016] [Indexed: 01/02/2023]
Abstract
BACKGROUND Inhibition of cellular topoisomerases has been established as an effective way of treating certain cancers, albeit with often high levels of toxicity to the bone marrow. While the involvement of mesenchymal stem cells (MSCs) in bone marrow homeostasis and regeneration has been well established, the effects of topoisomerase-inhibiting anticancer agents remain largely unknown. MATERIALS AND METHODS Human bone marrow MSCs were treated with topoisomerase I inhibitor irinotecan or topoisomerase II inhibitor etoposide, and survival and apoptosis levels were measured. The influence of topoisomerase inhibition on cellular morphology, adhesion and migration potential and the ability to differentiate was assessed. Additionally, the role of individual DNA double-strand break repair pathways in MSCs was investigated as a potential cellular mechanism of resistance to topoisomerase inhibitors. RESULTS Human bone marrow MSCs were found relatively resistant to topoisomerase I and II inhibitors and show survival levels comparable to these of differentiated fibroblasts. Treatment with irinotecan or etoposide did not significantly influence cellular adhesion, migratory ability, surface marker expression or induction of apoptosis in human MSCs. The ability to differentiate was found preserved in MSCs after exposure to high doses of irinotecan or etoposide. MSCs were able to efficiently repair DNA double-strand breaks induced by topoisomerase inhibitors both by non-homologous end joining and homologous recombination pathways. CONCLUSION Our data demonstrate a topoisomerase-resistant phenotype of human MSCs that may at least in part be due to the stem cells' ability to efficiently remove DNA damage caused by these anticancer agents. The observed resistance of MSCs warrants further investigation of these cells as a potential therapeutic option for treating topoisomerase inhibitor-induced bone marrow damage.
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Affiliation(s)
- Nils H Nicolay
- Department of Radiation Oncology, Heidelberg University Hospital, Im Neuenheimer Feld 400, 69120 Heidelberg, Germany; Heidelberg Institute for Radiation Oncology (HIRO), National Center for Radiation Research in Oncology, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany; Department of Molecular and Radiation Oncology, German Cancer Research Center (dkfz), Im Neuenheimer Feld 280, 69120 Heidelberg, Germany.
| | - Alexander Rühle
- Heidelberg Institute for Radiation Oncology (HIRO), National Center for Radiation Research in Oncology, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany; Department of Molecular and Radiation Oncology, German Cancer Research Center (dkfz), Im Neuenheimer Feld 280, 69120 Heidelberg, Germany
| | - Ramon Lopez Perez
- Department of Molecular and Radiation Oncology, German Cancer Research Center (dkfz), Im Neuenheimer Feld 280, 69120 Heidelberg, Germany
| | - Thuy Trinh
- Department of Radiation Oncology, Heidelberg University Hospital, Im Neuenheimer Feld 400, 69120 Heidelberg, Germany; Heidelberg Institute for Radiation Oncology (HIRO), National Center for Radiation Research in Oncology, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany
| | - Sonevisay Sisombath
- Department of Molecular and Radiation Oncology, German Cancer Research Center (dkfz), Im Neuenheimer Feld 280, 69120 Heidelberg, Germany
| | - Klaus-Josef Weber
- Department of Radiation Oncology, Heidelberg University Hospital, Im Neuenheimer Feld 400, 69120 Heidelberg, Germany; Heidelberg Institute for Radiation Oncology (HIRO), National Center for Radiation Research in Oncology, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany
| | - Peter Schmezer
- Department of Epigenomics and Cancer Risk Factors, German Cancer Research Center (dkfz), Im Neuenheimer Feld 280, 69120 Heidelberg, Germany
| | - Anthony D Ho
- Department of Hematology and Oncology, Heidelberg University Hospital, Im Neuenheimer Feld 410, 69120 Heidelberg, Germany
| | - Jürgen Debus
- Department of Radiation Oncology, Heidelberg University Hospital, Im Neuenheimer Feld 400, 69120 Heidelberg, Germany; Heidelberg Institute for Radiation Oncology (HIRO), National Center for Radiation Research in Oncology, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany
| | - Rainer Saffrich
- Department of Hematology and Oncology, Heidelberg University Hospital, Im Neuenheimer Feld 410, 69120 Heidelberg, Germany
| | - Peter E Huber
- Department of Radiation Oncology, Heidelberg University Hospital, Im Neuenheimer Feld 400, 69120 Heidelberg, Germany; Heidelberg Institute for Radiation Oncology (HIRO), National Center for Radiation Research in Oncology, Im Neuenheimer Feld 280, 69120 Heidelberg, Germany; Department of Molecular and Radiation Oncology, German Cancer Research Center (dkfz), Im Neuenheimer Feld 280, 69120 Heidelberg, Germany
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182
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Markiewicz E, Barnard S, Haines J, Coster M, van Geel O, Wu W, Richards S, Ainsbury E, Rothkamm K, Bouffler S, Quinlan RA. Nonlinear ionizing radiation-induced changes in eye lens cell proliferation, cyclin D1 expression and lens shape. Open Biol 2016; 5:150011. [PMID: 25924630 PMCID: PMC4422125 DOI: 10.1098/rsob.150011] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Elevated cataract risk after radiation exposure was established soon after the discovery of X-rays in 1895. Today, increased cataract incidence among medical imaging practitioners and after nuclear incidents has highlighted how little is still understood about the biological responses of the lens to low-dose ionizing radiation (IR). Here, we show for the first time that in mice, lens epithelial cells (LECs) in the peripheral region repair DNA double strand breaks (DSB) after exposure to 20 and 100 mGy more slowly compared with circulating blood lymphocytes, as demonstrated by counts of γH2AX foci in cell nuclei. LECs in the central region repaired DSBs faster than either LECs in the lens periphery or lymphocytes. Although DSB markers (γH2AX, 53BP1 and RAD51) in both lens regions showed linear dose responses at the 1 h timepoint, nonlinear responses were observed in lenses for EdU (5-ethynyl-2′-deoxy-uridine) incorporation, cyclin D1 staining and cell density after 24 h at 100 and 250 mGy. After 10 months, the lens aspect ratio was also altered, an indicator of the consequences of the altered cell proliferation and cell density changes. A best-fit model demonstrated a dose-response peak at 500 mGy. These data identify specific nonlinear biological responses to low (less than 1000 mGy) dose IR-induced DNA damage in the lens epithelium.
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Affiliation(s)
- Ewa Markiewicz
- School of Biological and Biomedical Sciences, University of Durham, Durham DH1 3LE, UK
| | - Stephen Barnard
- Public Health England, Centre for Radiation, Chemical & Environmental Hazards, Chilton, Didcot, Oxon OX11 0RQ, UK
| | - Jackie Haines
- Public Health England, Centre for Radiation, Chemical & Environmental Hazards, Chilton, Didcot, Oxon OX11 0RQ, UK
| | - Margaret Coster
- Public Health England, Centre for Radiation, Chemical & Environmental Hazards, Chilton, Didcot, Oxon OX11 0RQ, UK
| | - Orry van Geel
- School of Biological and Biomedical Sciences, University of Durham, Durham DH1 3LE, UK Faculty of Science, KU Leuven, Kasteelpark Arenberg 11, Leuven 3001, Belgium
| | - Weiju Wu
- School of Biological and Biomedical Sciences, University of Durham, Durham DH1 3LE, UK Biophysical Sciences Institute, University of Durham, Durham DH1 3LE, UK
| | - Shane Richards
- School of Biological and Biomedical Sciences, University of Durham, Durham DH1 3LE, UK
| | - Elizabeth Ainsbury
- Public Health England, Centre for Radiation, Chemical & Environmental Hazards, Chilton, Didcot, Oxon OX11 0RQ, UK
| | - Kai Rothkamm
- Public Health England, Centre for Radiation, Chemical & Environmental Hazards, Chilton, Didcot, Oxon OX11 0RQ, UK
| | - Simon Bouffler
- Public Health England, Centre for Radiation, Chemical & Environmental Hazards, Chilton, Didcot, Oxon OX11 0RQ, UK
| | - Roy A Quinlan
- School of Biological and Biomedical Sciences, University of Durham, Durham DH1 3LE, UK Biophysical Sciences Institute, University of Durham, Durham DH1 3LE, UK
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183
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The Rise of CRISPR/Cas for Genome Editing in Stem Cells. Stem Cells Int 2016; 2016:8140168. [PMID: 26880991 PMCID: PMC4736575 DOI: 10.1155/2016/8140168] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2015] [Revised: 11/03/2015] [Accepted: 11/05/2015] [Indexed: 12/26/2022] Open
Abstract
Genetic manipulation is a powerful tool to establish the causal relationship between a genetic lesion and a particular pathological phenotype. The rise of CRISPR/Cas9 genome-engineering tools overcame the traditional technical bottleneck for routine site-specific genetic manipulation in cells. To create the perfect in vitro cell model, there is significant interest from the stem cell research community to adopt this fast evolving technology. This review addresses this need directly by providing both the up-to-date biochemical rationale of CRISPR-mediated genome engineering and detailed practical guidelines for the design and execution of CRISPR experiments in cell models. Ultimately, this review will serve as a timely and comprehensive guide for this fast developing technology.
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184
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Nicolas E, Arora S, Zhou Y, Serebriiskii IG, Andrake MD, Handorf ED, Bodian DL, Vockley JG, Dunbrack RL, Ross EA, Egleston BL, Hall MJ, Golemis EA, Giri VN, Daly MB. Systematic evaluation of underlying defects in DNA repair as an approach to case-only assessment of familial prostate cancer. Oncotarget 2015; 6:39614-33. [PMID: 26485759 PMCID: PMC4741850 DOI: 10.18632/oncotarget.5554] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Accepted: 10/02/2015] [Indexed: 01/03/2023] Open
Abstract
Risk assessment for prostate cancer is challenging due to its genetic heterogeneity. In this study, our goal was to develop an operational framework to select and evaluate gene variants that may contribute to familial prostate cancer risk. Drawing on orthogonal sources, we developed a candidate list of genes relevant to prostate cancer, then analyzed germline exomes from 12 case-only prostate cancer patients from high-risk families to identify patterns of protein-damaging gene variants. We described an average of 5 potentially disruptive variants in each individual and annotated them in the context of public databases representing human variation. Novel damaging variants were found in several genes of relevance to prostate cancer. Almost all patients had variants associated with defects in DNA damage response. Many also had variants linked to androgen signaling. Treatment of primary T-lymphocytes from these prostate cancer patients versus controls with DNA damaging agents showed elevated levels of the DNA double strand break (DSB) marker γH2AX (p < 0.05), supporting the idea of an underlying defect in DNA repair. This work suggests the value of focusing on underlying defects in DNA damage in familial prostate cancer risk assessment and demonstrates an operational framework for exome sequencing in case-only prostate cancer genetic evaluation.
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Affiliation(s)
| | - Sanjeevani Arora
- Programs in Molecular Therapeutics Fox Chase Cancer Center, Philadelphia, PA, USA
| | - Yan Zhou
- Programs in Biostatistics, Fox Chase Cancer Center, Philadelphia, PA, USA
| | - Ilya G. Serebriiskii
- Programs in Molecular Therapeutics Fox Chase Cancer Center, Philadelphia, PA, USA
- Kazan Federal University, Kazan, Russia
| | - Mark D. Andrake
- Programs in Molecular Therapeutics Fox Chase Cancer Center, Philadelphia, PA, USA
| | | | - Dale L. Bodian
- Inova Translational Medicine Institute, Inova Health System, Falls Church, VA, USA
| | - Joseph G. Vockley
- Inova Translational Medicine Institute, Inova Health System, Falls Church, VA, USA
| | - Roland L. Dunbrack
- Programs in Molecular Therapeutics Fox Chase Cancer Center, Philadelphia, PA, USA
| | - Eric A. Ross
- Programs in Biostatistics, Fox Chase Cancer Center, Philadelphia, PA, USA
| | - Brian L. Egleston
- Programs in Biostatistics, Fox Chase Cancer Center, Philadelphia, PA, USA
| | - Michael J. Hall
- Cancer Prevention and Control, Fox Chase Cancer Center, Philadelphia, PA, USA
| | - Erica A. Golemis
- Programs in Molecular Therapeutics Fox Chase Cancer Center, Philadelphia, PA, USA
| | - Veda N. Giri
- Sidney Kimmel Cancer Center at Thomas Jefferson University, Philadelphia, PA, USA
| | - Mary B. Daly
- Cancer Prevention and Control, Fox Chase Cancer Center, Philadelphia, PA, USA
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185
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Rall M, Kraft D, Volcic M, Cucu A, Nasonova E, Taucher-Scholz G, Bönig H, Wiesmüller L, Fournier C. Impact of Charged Particle Exposure on Homologous DNA Double-Strand Break Repair in Human Blood-Derived Cells. Front Oncol 2015; 5:250. [PMID: 26618143 PMCID: PMC4641431 DOI: 10.3389/fonc.2015.00250] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2015] [Accepted: 10/26/2015] [Indexed: 12/12/2022] Open
Abstract
Ionizing radiation generates DNA double-strand breaks (DSB) which, unless faithfully repaired, can generate chromosomal rearrangements in hematopoietic stem and/or progenitor cells (HSPC), potentially priming the cells towards a leukemic phenotype. Using an enhanced green fluorescent protein (EGFP)-based reporter system, we recently identified differences in the removal of enzyme-mediated DSB in human HSPC versus mature peripheral blood lymphocytes (PBL), particularly regarding homologous DSB repair (HR). Assessment of chromosomal breaks via premature chromosome condensation or γH2AX foci indicated similar efficiency and kinetics of radiation-induced DSB formation and rejoining in PBL and HSPC. Prolonged persistence of chromosomal breaks was observed for higher LET charged particles which are known to induce more complex DNA damage compared to X-rays. Consistent with HR deficiency in HSPC observed in our previous study, we noticed here pronounced focal accumulation of 53BP1 after X-ray and carbon ion exposure (intermediate LET) in HSPC versus PBL. For higher LET, 53BP1 foci kinetics was similarly delayed in PBL and HSPC suggesting similar failure to repair complex DNA damage. Data obtained with plasmid reporter systems revealed a dose- and LET-dependent HR increase after X-ray, carbon ion and higher LET exposure, particularly in HR-proficient immortalized and primary lymphocytes, confirming preferential use of conservative HR in PBL for intermediate LET damage repair. HR measured adjacent to the leukemia-associated MLL breakpoint cluster sequence in reporter lines revealed dose dependency of potentially leukemogenic rearrangements underscoring the risk of leukemia-induction by radiation treatment.
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Affiliation(s)
- Melanie Rall
- Department of Obstetrics and Gynaecology, Ulm University, Ulm, Germany
| | - Daniela Kraft
- Department of Biophysics, GSI Helmholtz Center for Heavy Ion Research, Darmstadt, Germany
| | - Meta Volcic
- Department of Obstetrics and Gynaecology, Ulm University, Ulm, Germany
| | - Aljona Cucu
- Department of Biophysics, GSI Helmholtz Center for Heavy Ion Research, Darmstadt, Germany
| | - Elena Nasonova
- Department of Biophysics, GSI Helmholtz Center for Heavy Ion Research, Darmstadt, Germany
| | - Gisela Taucher-Scholz
- Department of Biophysics, GSI Helmholtz Center for Heavy Ion Research, Darmstadt, Germany
| | - Halvard Bönig
- German Red Cross Blood Service Baden-Wuerttemberg – Hessen, Institute for Transfusion Medicine and Immunohematology, Johann Wolfgang Goethe-University Hospital, Frankfurt, Germany
| | - Lisa Wiesmüller
- Department of Obstetrics and Gynaecology, Ulm University, Ulm, Germany
- *Correspondence: Lisa Wiesmüller, ; Claudia Fournier,
| | - Claudia Fournier
- Department of Biophysics, GSI Helmholtz Center for Heavy Ion Research, Darmstadt, Germany
- *Correspondence: Lisa Wiesmüller, ; Claudia Fournier,
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186
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Hamada N, Fujimichi Y. Role of carcinogenesis related mechanisms in cataractogenesis and its implications for ionizing radiation cataractogenesis. Cancer Lett 2015; 368:262-74. [DOI: 10.1016/j.canlet.2015.02.017] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Revised: 02/09/2015] [Accepted: 02/10/2015] [Indexed: 12/20/2022]
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187
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Sekhar KR, Freeman ML. Nrf2 promotes survival following exposure to ionizing radiation. Free Radic Biol Med 2015; 88:268-274. [PMID: 25975985 PMCID: PMC4628893 DOI: 10.1016/j.freeradbiomed.2015.04.035] [Citation(s) in RCA: 77] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Revised: 04/28/2015] [Accepted: 04/30/2015] [Indexed: 12/30/2022]
Abstract
Nrf2 is a transcription factor that promotes antioxidant and drug-metabolizing gene expression. It also regulates the transcription of genes involved in carbohydrate and lipid metabolism, NADPH regeneration, and heme and iron metabolism, as well as proteasome metabolism. Emerging research has identified Nrf2 as a critical factor for promoting survival of mammalian cells subjected to ionizing radiation. At a mechanistic level, Nrf2 promotes the repair of DNA damage and drives detoxification of superoxide that is generated hours to days after irradiation. This review summarizes research in these areas and discusses targeting of Nrf2 in radiation-resistant cancer and Nrf2׳s role in mitigating acute radiation syndrome.
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Affiliation(s)
- Konjeti R Sekhar
- Department of Radiation Oncology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | - Michael L Freeman
- Department of Radiation Oncology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA.
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188
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Westmoreland JW, Resnick MA. Recombinational repair of radiation-induced double-strand breaks occurs in the absence of extensive resection. Nucleic Acids Res 2015; 44:695-704. [PMID: 26503252 PMCID: PMC4737140 DOI: 10.1093/nar/gkv1109] [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: 04/06/2015] [Accepted: 10/13/2015] [Indexed: 02/07/2023] Open
Abstract
Recombinational repair provides accurate chromosomal restitution after double-strand break (DSB) induction. While all DSB recombination repair models include 5′-3′ resection, there are no studies that directly assess the resection needed for repair between sister chromatids in G-2 arrested cells of random, radiation-induced ‘dirty’ DSBs. Using our Pulse Field Gel Electrophoresis-shift approach, we determined resection at IR-DSBs in WT and mutants lacking exonuclease1 or Sgs1 helicase. Lack of either reduced resection length by half, without decreased DSB repair or survival. In the exo1Δ sgs1Δ double mutant, resection was barely detectable, yet it only took an additional hour to achieve a level of repair comparable to WT and there was only a 2-fold dose-modifying effect on survival. Results with a Dnl4 deletion strain showed that remaining repair was not due to endjoining. Thus, similar to what has been shown for a single, clean HO-induced DSB, a severe reduction in resection tract length has only a modest effect on repair of multiple, dirty DSBs in G2-arrested cells. Significantly, this study provides the first opportunity to directly relate resection length at DSBs to the capability for global recombination repair between sister chromatids.
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Affiliation(s)
- James W Westmoreland
- Chromosome Stability Section, Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, NIH, Research Triangle Park, NC 27709, USA
| | - Michael A Resnick
- Chromosome Stability Section, Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, NIH, Research Triangle Park, NC 27709, USA
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189
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Van Houten B. Pulmonary Arterial Hypertension Is Associated with Oxidative Stress-induced Genome Instability. Am J Respir Crit Care Med 2015; 192:129-30. [PMID: 26177169 DOI: 10.1164/rccm.201505-0904ed] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Affiliation(s)
- Bennett Van Houten
- 1 Department of Pharmacology and Chemical Biology and.,2 University of Pittsburgh Cancer Institute University of Pittsburgh School of Medicine Pittsburgh, Pennsylvania
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190
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Pinder J, Salsman J, Dellaire G. Nuclear domain 'knock-in' screen for the evaluation and identification of small molecule enhancers of CRISPR-based genome editing. Nucleic Acids Res 2015; 43:9379-92. [PMID: 26429972 PMCID: PMC4627099 DOI: 10.1093/nar/gkv993] [Citation(s) in RCA: 195] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2015] [Accepted: 09/21/2015] [Indexed: 12/31/2022] Open
Abstract
CRISPR is a genome-editing platform that makes use of the bacterially-derived endonuclease Cas9 to introduce DNA double-strand breaks at precise locations in the genome using complementary guide RNAs. We developed a nuclear domain knock-in screen, whereby the insertion of a gene encoding the green fluorescent protein variant Clover is inserted by Cas9-mediated homology directed repair (HDR) within the first exon of genes that are required for the structural integrity of subnuclear domains such as the nuclear lamina and promyelocytic leukemia nuclear bodies (PML NBs). Using this approach, we compared strategies for enhancing CRISPR-mediated HDR, focusing on known genes and small molecules that impact non-homologous end joining (NHEJ) and homologous recombination (HR). Ultimately, we identified the small molecule RS-1 as a potent enhancer of CRISPR-based genome editing, enhancing HDR 3- to 6-fold depending on the locus and transfection method. We also characterized U2OS human osteosarcoma cells expressing Clover-tagged PML and demonstrate that this strategy generates cell lines with PML NBs that are structurally and functionally similar to bodies in the parental cell line. Thus, the nuclear domain knock-in screen that we describe provides a simple means of rapidly evaluating methods and small molecules that have the potential to enhance Cas9-mediated HDR.
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Affiliation(s)
- Jordan Pinder
- Department of Pathology, Dalhousie University, Halifax, Nova Scotia, B3H 4R2, Canada
| | - Jayme Salsman
- Department of Pathology, Dalhousie University, Halifax, Nova Scotia, B3H 4R2, Canada
| | - Graham Dellaire
- Department of Pathology, Dalhousie University, Halifax, Nova Scotia, B3H 4R2, Canada Department of Biochemistry & Molecular Biology, Dalhousie University, Halifax, Nova Scotia, B3H 4R2, Canada Beatrice Hunter Cancer Research Institute, Halifax, Nova Scotia, B3H 4R2, Canada
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191
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Saito Y, Komatsu K. Functional Role of NBS1 in Radiation Damage Response and Translesion DNA Synthesis. Biomolecules 2015; 5:1990-2002. [PMID: 26308066 PMCID: PMC4598784 DOI: 10.3390/biom5031990] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Revised: 08/11/2015] [Accepted: 08/13/2015] [Indexed: 12/15/2022] Open
Abstract
Nijmegen breakage syndrome (NBS) is a recessive genetic disorder characterized by increased sensitivity to ionizing radiation (IR) and a high frequency of malignancies. NBS1, a product of the mutated gene in NBS, contains several protein interaction domains in the N-terminus and C-terminus. The C-terminus of NBS1 is essential for interactions with MRE11, a homologous recombination repair nuclease, and ATM, a key player in signal transduction after the generation of DNA double-strand breaks (DSBs), which is induced by IR. Moreover, NBS1 regulates chromatin remodeling during DSB repair by histone H2B ubiquitination through binding to RNF20 at the C-terminus. Thus, NBS1 is considered as the first protein to be recruited to DSB sites, wherein it acts as a sensor or mediator of DSB damage responses. In addition to DSB response, we showed that NBS1 initiates Polη-dependent translesion DNA synthesis by recruiting RAD18 through its binding at the NBS1 C-terminus after UV exposure, and it also functions after the generation of interstrand crosslink DNA damage. Thus, NBS1 has multifunctional roles in response to DNA damage from a variety of genotoxic agents, including IR.
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Affiliation(s)
- Yuichiro Saito
- Genome Repair Dynamics, Radiation Biology Center, Kyoto University, Yoshida Konoe, Sakyo-ku, Kyoto 606-8501, Japan.
| | - Kenshi Komatsu
- Genome Repair Dynamics, Radiation Biology Center, Kyoto University, Yoshida Konoe, Sakyo-ku, Kyoto 606-8501, Japan.
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192
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Ahn JW, Kim S, Na W, Baek SJ, Kim JH, Min K, Yeom J, Kwak H, Jeong S, Lee C, Kim SY, Choi CY. SERBP1 affects homologous recombination-mediated DNA repair by regulation of CtIP translation during S phase. Nucleic Acids Res 2015; 43:6321-33. [PMID: 26068472 PMCID: PMC4513868 DOI: 10.1093/nar/gkv592] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2014] [Revised: 05/13/2015] [Accepted: 05/24/2015] [Indexed: 11/12/2022] Open
Abstract
DNA double-strand breaks (DSBs) are the most severe type of DNA damage and are primarily repaired by non-homologous end joining (NHEJ) and homologous recombination (HR) in the G1 and S/G2 phase, respectively. Although CtBP-interacting protein (CtIP) is crucial in DNA end resection during HR following DSBs, little is known about how CtIP levels increase in an S phase-specific manner. Here, we show that Serpine mRNA binding protein 1 (SERBP1) regulates CtIP expression at the translational level in S phase. In response to camptothecin-mediated DNA DSBs, CHK1 and RPA2 phosphorylation, which are hallmarks of HR activation, was abrogated in SERBP1-depleted cells. We identified CtIP mRNA as a binding target of SERBP1 using RNA immunoprecipitation-coupled RNA sequencing, and confirmed SERBP1 binding to CtIP mRNA in S phase. SERBP1 depletion resulted in reduction of polysome-associated CtIP mRNA and concomitant loss of CtIP expression in S phase. These effects were reversed by reconstituting cells with wild-type SERBP1, but not by SERBP1 ΔRGG, an RNA binding defective mutant, suggesting regulation of CtIP translation by SERBP1 association with CtIP mRNA. These results indicate that SERBP1 affects HR-mediated DNA repair in response to DNA DSBs by regulation of CtIP translation in S phase.
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Affiliation(s)
- Jang-Won Ahn
- Department of Biological Sciences, Sungkyunkwan University, Suwon 440-746, Republic of Korea
| | - Sunjik Kim
- Department of Biological Sciences, Sungkyunkwan University, Suwon 440-746, Republic of Korea
| | - Wooju Na
- Department of Biological Sciences, Sungkyunkwan University, Suwon 440-746, Republic of Korea
| | - Su-Jin Baek
- Human Genomics Research Center, KRIBB, Daejeon 305-806, Republic of Korea Department of Functional Genomics, University of Science of Technology, Daejeon 305-350, Republic of Korea
| | - Jeong-Hwan Kim
- Human Genomics Research Center, KRIBB, Daejeon 305-806, Republic of Korea
| | - Keehong Min
- Department of Biological Sciences, Sungkyunkwan University, Suwon 440-746, Republic of Korea
| | - Jeonghun Yeom
- Center for Theragnosis, Korea Institute of Science and Technology, Seoul 136-791, Republic of Korea Department of Biological Chemistry, University of Science and Technology, Daejeon 305-333, Republic of Korea
| | - Hoyun Kwak
- Department of Molecular Biology, Dankook University, Yongin 448-701, Republic of Korea
| | - Sunjoo Jeong
- Department of Molecular Biology, Dankook University, Yongin 448-701, Republic of Korea
| | - Cheolju Lee
- Center for Theragnosis, Korea Institute of Science and Technology, Seoul 136-791, Republic of Korea Department of Biological Chemistry, University of Science and Technology, Daejeon 305-333, Republic of Korea
| | - Seon-Young Kim
- Human Genomics Research Center, KRIBB, Daejeon 305-806, Republic of Korea Department of Functional Genomics, University of Science of Technology, Daejeon 305-350, Republic of Korea
| | - Cheol Yong Choi
- Department of Biological Sciences, Sungkyunkwan University, Suwon 440-746, Republic of Korea
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193
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Fukuda T, Wu W, Okada M, Maeda I, Kojima Y, Hayami R, Miyoshi Y, Tsugawa KI, Ohta T. Class I histone deacetylase inhibitors inhibit the retention of BRCA1 and 53BP1 at the site of DNA damage. Cancer Sci 2015; 106:1050-6. [PMID: 26053117 PMCID: PMC4556395 DOI: 10.1111/cas.12717] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2015] [Revised: 05/08/2015] [Accepted: 06/03/2015] [Indexed: 01/06/2023] Open
Abstract
BRCA1 and 53BP1 antagonistically regulate homology-directed repair (HDR) and non-homologous end-joining (NHEJ) of DNA double-strand breaks (DSB). The histone deacetylase (HDAC) inhibitor trichostatin A directly inhibits the retention of 53BP1 at DSB sites by acetylating histone H4 (H4ac), which interferes with 53BP1 binding to dimethylated histone H4 Lys20 (H4K20me2). Conversely, we recently found that the retention of the BRCA1/BARD1 complex is also affected by another methylated histone residue, H3K9me2, which can be suppressed by the histone lysine methyltransferase (HKMT) inhibitor UNC0638. Here, we investigate the effects of the class I HDAC inhibitors MS-275 and FK228 compared to UNC0638 on histone modifications and the DNA damage response. In addition to H4ac, the HDAC inhibitors induce H3K9ac and inhibit H3K9me2 at doses that do not affect the expression levels of DNA repair genes. By contrast, UNC0638 selectively inhibits H3K9me2 without affecting the levels of H3K9ac, H3K56ac or H4ac. Reflecting their effects on histone modifications, the HDAC inhibitors inhibit ionizing radiation-induced foci (IRIF) formation of BRCA1 and BARD1 as well as 53BP1 and RIF1, whereas UNC0638 suppresses IRIF formation of BRCA1 and BARD1 but not 53BP1 and RIF1. Although HDAC inhibitors suppressed HDR, they did not cooperate with the poly(ADP-ribose) polymerase inhibitor olaparib to block cancer cell growth, possibly due to simultaneous suppression of NHEJ pathway components. Collectively, these results suggest the mechanism by that HDAC inhibitors inhibit both the HDR and NHEJ pathways, whereas HKMT inhibitor inhibits only the HDR pathway; this finding may affect the chemosensitizing effects of the inhibitors.
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Affiliation(s)
- Takayo Fukuda
- Department of Translational Oncology, St. Marianna University Graduate School of Medicine, Kawasaki, Japan
| | - Wenwen Wu
- Department of Translational Oncology, St. Marianna University Graduate School of Medicine, Kawasaki, Japan
| | - Maiko Okada
- Department of Translational Oncology, St. Marianna University Graduate School of Medicine, Kawasaki, Japan
| | - Ichiro Maeda
- Department of Pathology, St. Marianna University Graduate School of Medicine, Kawasaki, Japan
| | - Yasuyuki Kojima
- Division of Breast and Endocrine Surgery, Department of Surgery, St. Marianna University Graduate School of Medicine, Kawasaki, Japan
| | - Ryosuke Hayami
- Division of Breast and Endocrine Surgery, Department of Surgery, St. Marianna University Graduate School of Medicine, Kawasaki, Japan
| | - Yasuo Miyoshi
- Division of Breast and Endocrine Surgery, Department of Surgery, Hyogo College of Medicine, Hyogo, Japan
| | - Ko-ichiro Tsugawa
- Division of Breast and Endocrine Surgery, Department of Surgery, St. Marianna University Graduate School of Medicine, Kawasaki, Japan
| | - Tomohiko Ohta
- Department of Translational Oncology, St. Marianna University Graduate School of Medicine, Kawasaki, Japan
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194
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Rothkamm K, Barnard S, Moquet J, Ellender M, Rana Z, Burdak-Rothkamm S. DNA damage foci: Meaning and significance. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2015; 56:491-504. [PMID: 25773265 DOI: 10.1002/em.21944] [Citation(s) in RCA: 218] [Impact Index Per Article: 24.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2014] [Accepted: 02/13/2015] [Indexed: 06/04/2023]
Abstract
The discovery of DNA damage response proteins such as γH2AX, ATM, 53BP1, RAD51, and the MRE11/RAD50/NBS1 complex, that accumulate and/or are modified in the vicinity of a chromosomal DNA double-strand break to form microscopically visible, subnuclear foci, has revolutionized the detection of these lesions and has enabled studies of the cellular machinery that contributes to their repair. Double-strand breaks are induced directly by a number of physical and chemical agents, including ionizing radiation and radiomimetic drugs, but can also arise as secondary lesions during replication and DNA repair following exposure to a wide range of genotoxins. Here we aim to review the biological meaning and significance of DNA damage foci, looking specifically at a range of different settings in which such markers of DNA damage and repair are being studied and interpreted.
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Affiliation(s)
- Kai Rothkamm
- Public Health England, Centre for Radiation, Chemical and Environmental Hazards, Chilton, United Kingdom
- Department of Radiotherapy, Laboratory of Radiation Biology and Experimental Radiation Oncology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Stephen Barnard
- Public Health England, Centre for Radiation, Chemical and Environmental Hazards, Chilton, United Kingdom
| | - Jayne Moquet
- Public Health England, Centre for Radiation, Chemical and Environmental Hazards, Chilton, United Kingdom
| | - Michele Ellender
- Public Health England, Centre for Radiation, Chemical and Environmental Hazards, Chilton, United Kingdom
| | - Zohaib Rana
- Public Health England, Centre for Radiation, Chemical and Environmental Hazards, Chilton, United Kingdom
| | - Susanne Burdak-Rothkamm
- Department of Cellular Pathology, Oxford University Hospitals, Headley Way, Headington, Oxford, United Kingdom
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195
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Tsuchida E, Kaida A, Pratama E, Ikeda MA, Suzuki K, Harada K, Miura M. Effect of X-Irradiation at Different Stages in the Cell Cycle on Individual Cell-Based Kinetics in an Asynchronous Cell Population. PLoS One 2015; 10:e0128090. [PMID: 26086724 PMCID: PMC4472673 DOI: 10.1371/journal.pone.0128090] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2014] [Accepted: 04/23/2015] [Indexed: 12/20/2022] Open
Abstract
Using an asynchronously growing cell population, we investigated how X-irradiation at different stages of the cell cycle influences individual cell–based kinetics. To visualize the cell-cycle phase, we employed the fluorescent ubiquitination-based cell cycle indicator (Fucci). After 5 Gy irradiation, HeLa cells no longer entered M phase in an order determined by their previous stage of the cell cycle, primarily because green phase (S and G2) was less prolonged in cells irradiated during the red phase (G1) than in those irradiated during the green phase. Furthermore, prolongation of the green phase in cells irradiated during the red phase gradually increased as the irradiation timing approached late G1 phase. The results revealed that endoreduplication rarely occurs in this cell line under the conditions we studied. We next established a method for classifying the green phase into early S, mid S, late S, and G2 phases at the time of irradiation, and then attempted to estimate the duration of G2 arrest based on certain assumptions. The value was the largest when cells were irradiated in mid or late S phase and the smallest when they were irradiated in G1 phase. In this study, by closely following individual cells irradiated at different cell-cycle phases, we revealed for the first time the unique cell-cycle kinetics in HeLa cells that follow irradiation.
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Affiliation(s)
- Eri Tsuchida
- Section of Oral Radiation Oncology, Department of Oral Health Sciences, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113–8549, Japan
- Section of Maxillofacial Surgery, Department of Maxillofacial and Neck Reconstruction, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113–8549, Japan
| | - Atsushi Kaida
- Section of Oral Radiation Oncology, Department of Oral Health Sciences, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113–8549, Japan
| | - Endrawan Pratama
- Section of Molecular Craniofacial Embryology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113–8549, Japan
| | - Masa-Aki Ikeda
- Section of Molecular Craniofacial Embryology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113–8549, Japan
| | - Keiji Suzuki
- Department of Radiation Medical Sciences, Atomic Bomb Disease Institute, Nagasaki University Graduate School of Biomedical Sciences, 1-12-4 Sakamoto, Nagasaki, 852–8523, Japan
| | - Kiyoshi Harada
- Section of Maxillofacial Surgery, Department of Maxillofacial and Neck Reconstruction, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113–8549, Japan
| | - Masahiko Miura
- Section of Oral Radiation Oncology, Department of Oral Health Sciences, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113–8549, Japan
- * E-mail:
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196
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Koeppel M, Garcia-Alcalde F, Glowinski F, Schlaermann P, Meyer T. Helicobacter pylori Infection Causes Characteristic DNA Damage Patterns in Human Cells. Cell Rep 2015; 11:1703-13. [DOI: 10.1016/j.celrep.2015.05.030] [Citation(s) in RCA: 97] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2014] [Revised: 03/10/2015] [Accepted: 05/16/2015] [Indexed: 01/09/2023] Open
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197
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Abstract
DNA double-strand breaks (DSBs) in cells can undergo nucleolytic degradation to generate long 3' single-stranded DNA tails. This process is termed DNA end resection, and its occurrence effectively commits to break repair via homologous recombination, which entails the acquisition of genetic information from an intact, homologous donor DNA sequence. Recent advances, prompted by the identification of the nucleases that catalyze resection, have revealed intricate layers of functional redundancy, interconnectedness, and regulation. Here, we review the current state of the field with an emphasis on the major questions that remain to be answered. Topics addressed will include how resection initiates via the introduction of an endonucleolytic incision close to the break end, the molecular mechanism of the conserved MRE11 complex in conjunction with Sae2/CtIP within such a model, the role of BRCA1 and 53BP1 in regulating resection initiation in mammalian cells, the influence of chromatin in the resection process, and potential roles of novel factors.
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Affiliation(s)
- James M Daley
- Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, CT 06520, USA.
| | - Hengyao Niu
- Molecular and Cellular Biochemistry Department, Indiana University, Bloomington, IN 47405, USA
| | - Adam S Miller
- Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Patrick Sung
- Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, CT 06520, USA
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198
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Zong D, Callén E, Pegoraro G, Lukas C, Lukas J, Nussenzweig A. Ectopic expression of RNF168 and 53BP1 increases mutagenic but not physiological non-homologous end joining. Nucleic Acids Res 2015; 43:4950-61. [PMID: 25916843 PMCID: PMC4446425 DOI: 10.1093/nar/gkv336] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Accepted: 04/01/2015] [Indexed: 11/13/2022] Open
Abstract
DNA double strand breaks (DSBs) formed during S phase are preferentially repaired by homologous recombination (HR), whereas G1 DSBs, such as those occurring during immunoglobulin class switch recombination (CSR), are repaired by non-homologous end joining (NHEJ). The DNA damage response proteins 53BP1 and BRCA1 regulate the balance between NHEJ and HR. 53BP1 promotes CSR in part by mediating synapsis of distal DNA ends, and in addition, inhibits 5’ end resection. BRCA1 antagonizes 53BP1 dependent DNA end-blocking activity during S phase, which would otherwise promote mutagenic NHEJ and genome instability. Recently, it was shown that supra-physiological levels of the E3 ubiquitin ligase RNF168 results in the hyper-accumulation of 53BP1/BRCA1 which accelerates DSB repair. Here, we ask whether increased expression of RNF168 or 53BP1 impacts physiological versus mutagenic NHEJ. We find that the anti-resection activities of 53BP1 are rate-limiting for mutagenic NHEJ but not for physiological CSR. As heterogeneity in the expression of RNF168 and 53BP1 is found in human tumors, our results suggest that deregulation of the RNF168/53BP1 pathway could alter the chemosensitivity of BRCA1 deficient tumors.
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Affiliation(s)
- Dali Zong
- Laboratory of Genome Integrity; National Cancer Institute; National Institutes of Health; Bethesda, MD 20892, USA
| | - Elsa Callén
- Laboratory of Genome Integrity; National Cancer Institute; National Institutes of Health; Bethesda, MD 20892, USA
| | - Gianluca Pegoraro
- Center for Cancer Research, National Cancer Institute; National Institute of Health, Bethesda, MD 20892, USA
| | - Claudia Lukas
- The Novo Nordisk Foundation Center for Protein Research, University of Copenhagen, Faculty of Health and Medical Sciences, Blegdamsvej 3, 2200, Copenhagen, Denmark
| | - Jiri Lukas
- The Novo Nordisk Foundation Center for Protein Research, University of Copenhagen, Faculty of Health and Medical Sciences, Blegdamsvej 3, 2200, Copenhagen, Denmark
| | - André Nussenzweig
- Laboratory of Genome Integrity; National Cancer Institute; National Institutes of Health; Bethesda, MD 20892, USA
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199
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Stavnezer J, Schrader CE. IgH chain class switch recombination: mechanism and regulation. THE JOURNAL OF IMMUNOLOGY 2015; 193:5370-8. [PMID: 25411432 DOI: 10.4049/jimmunol.1401849] [Citation(s) in RCA: 168] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
IgH class switching occurs rapidly after activation of mature naive B cells, resulting in a switch from expression of IgM and IgD to expression of IgG, IgE, or IgA; this switch improves the ability of Abs to remove the pathogen that induces the humoral immune response. Class switching occurs by a deletional recombination between two switch regions, each of which is associated with a H chain constant region gene. Class switch recombination (CSR) is instigated by activation-induced cytidine deaminase, which converts cytosines in switch regions to uracils. The uracils are subsequently removed by two DNA-repair pathways, resulting in mutations, single-strand DNA breaks, and the double-strand breaks required for CSR. We discuss several aspects of CSR, including how CSR is induced, CSR in B cell progenitors, the roles of transcription and chromosomal looping in CSR, and the roles of certain DNA-repair enzymes in CSR.
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Affiliation(s)
- Janet Stavnezer
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, MA 01605
| | - Carol E Schrader
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, MA 01605
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200
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Batenburg NL, Thompson EL, Hendrickson EA, Zhu XD. Cockayne syndrome group B protein regulates DNA double-strand break repair and checkpoint activation. EMBO J 2015; 34:1399-416. [PMID: 25820262 DOI: 10.15252/embj.201490041] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2014] [Accepted: 03/11/2015] [Indexed: 11/09/2022] Open
Abstract
Mutations of CSB account for the majority of Cockayne syndrome (CS), a devastating hereditary disorder characterized by physical impairment, neurological degeneration and segmental premature aging. Here we report the generation of a human CSB-knockout cell line. We find that CSB facilitates HR and represses NHEJ. Loss of CSB or a CS-associated CSB mutation abrogating its ATPase activity impairs the recruitment of BRCA1, RPA and Rad51 proteins to damaged chromatin but promotes the formation of 53BP1-Rif1 damage foci in S and G2 cells. Depletion of 53BP1 rescues the formation of BRCA1 damage foci in CSB-knockout cells. In addition, knockout of CSB impairs the ATM- and Chk2-mediated DNA damage responses, promoting a premature entry into mitosis. Furthermore, we show that CSB accumulates at sites of DNA double-strand breaks (DSBs) in a transcription-dependent manner. The kinetics of DSB-induced chromatin association of CSB is distinct from that of its UV-induced chromatin association. These results reveal novel, important functions of CSB in regulating the DNA DSB repair pathway choice as well as G2/M checkpoint activation.
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Affiliation(s)
| | - Elizabeth L Thompson
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota Medical School, Minneapolis, MN, USA
| | - Eric A Hendrickson
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota Medical School, Minneapolis, MN, USA
| | - Xu-Dong Zhu
- Department of Biology, McMaster University, Hamilton, ON, Canada
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