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Pascarella G, Conner KN, Goff NJ, Carninci P, Olive AJ, Meek K. Compared to other NHEJ factors, DNA-PK protein and RNA levels are markedly increased in all higher primates, but not in prosimians or other mammals. DNA Repair (Amst) 2024; 142:103737. [PMID: 39128395 DOI: 10.1016/j.dnarep.2024.103737] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2024] [Revised: 07/23/2024] [Accepted: 07/24/2024] [Indexed: 08/13/2024]
Abstract
The DNA dependent protein kinase (DNA-PK) initiates non-homologous recombination (NHEJ), the predominate DNA double-strand break (DSBR) pathway in higher vertebrates. It has been known for decades that the enzymatic activity of DNA-PK [that requires its three component polypeptides, Ku70, Ku80 (that comprise the DNA-end binding Ku heterodimer), and the catalytic subunit (DNA-PKcs)] is present in humans at 10-50 times the level observed in other mammals. Here, we show that the high level of DNA-PKcs protein expression appears evolutionarily in mammals between prosimians and higher primates. Moreover, the RNAs encoding the three component polypeptides of DNA-PK are present at similarly high levels in hominids, new-, and old-world monkeys, but expression of these RNAs in prosimians is ∼5-50 fold less, analogous to the levels observed in other non-primate species. This is reminiscent of the appearance of Alu repeats in primate genomes -- abundant in higher primates, but present at much lower density in prosimians. Alu repeats are well-known for their capacity to promote non-allelic homologous recombination (NAHR) a process known to be inhibited by DNA-PK. Nanopore sequence analyses of cultured cells proficient or deficient in DNA-PK revealed an increase of inter-chromosomal translocations caused by NAHR. Although the high levels of DNA-PK in primates may have many functions, we posit that high levels of DNA-PK may function to restrain deleterious NAHR events between Alu elements.
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Affiliation(s)
| | - Kayla N Conner
- Department of Microbiology, Genetics, and Immunology, Michigan State University, East Lansing, MI 48824, USA
| | - Noah J Goff
- Department of Microbiology, Genetics, and Immunology, Michigan State University, East Lansing, MI 48824, USA; Department of Pathobiology & Diagnostic Investigation, Michigan State University, East Lansing, MI 48824, USA
| | - Piero Carninci
- RIKEN Center for Integrative Medical Sciences (IMS), Yokohama, Japan; Human Technopole, Milan, Italy
| | - Andrew J Olive
- Department of Microbiology, Genetics, and Immunology, Michigan State University, East Lansing, MI 48824, USA
| | - Katheryn Meek
- Department of Microbiology, Genetics, and Immunology, Michigan State University, East Lansing, MI 48824, USA; Department of Pathobiology & Diagnostic Investigation, Michigan State University, East Lansing, MI 48824, USA.
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2
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Wu J, Song L, Lu M, Gao Q, Xu S, Zhou P, Ma T. The multifaceted functions of DNA-PKcs: implications for the therapy of human diseases. MedComm (Beijing) 2024; 5:e613. [PMID: 38898995 PMCID: PMC11185949 DOI: 10.1002/mco2.613] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2023] [Revised: 05/07/2024] [Accepted: 05/09/2024] [Indexed: 06/21/2024] Open
Abstract
The DNA-dependent protein kinase (DNA-PK), catalytic subunit, also known as DNA-PKcs, is complexed with the heterodimer Ku70/Ku80 to form DNA-PK holoenzyme, which is well recognized as initiator in the nonhomologous end joining (NHEJ) repair after double strand break (DSB). During NHEJ, DNA-PKcs is essential for both DNA end processing and end joining. Besides its classical function in DSB repair, DNA-PKcs also shows multifaceted functions in various biological activities such as class switch recombination (CSR) and variable (V) diversity (D) joining (J) recombination in B/T lymphocytes development, innate immunity through cGAS-STING pathway, transcription, alternative splicing, and so on, which are dependent on its function in NHEJ or not. Moreover, DNA-PKcs deficiency has been proven to be related with human diseases such as neurological pathogenesis, cancer, immunological disorder, and so on through different mechanisms. Therefore, it is imperative to summarize the latest findings about DNA-PKcs and diseases for better targeting DNA-PKcs, which have shown efficacy in cancer treatment in preclinical models. Here, we discuss the multifaceted roles of DNA-PKcs in human diseases, meanwhile, we discuss the progresses of DNA-PKcs inhibitors and their potential in clinical trials. The most updated review about DNA-PKcs will hopefully provide insights and ideas to understand DNA-PKcs associated diseases.
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Affiliation(s)
- Jinghong Wu
- Cancer Research CenterBeijing Chest HospitalCapital Medical University/Beijing Tuberculosis and Thoracic Tumor Research InstituteBeijingChina
| | - Liwei Song
- Department of Thoracic SurgeryBeijing Chest HospitalCapital Medical University, Beijing Tuberculosis and Thoracic Tumor Research InstituteBeijingChina
| | - Mingjun Lu
- Cancer Research CenterBeijing Chest HospitalCapital Medical University/Beijing Tuberculosis and Thoracic Tumor Research InstituteBeijingChina
| | - Qing Gao
- Cancer Research CenterBeijing Chest HospitalCapital Medical University/Beijing Tuberculosis and Thoracic Tumor Research InstituteBeijingChina
| | - Shaofa Xu
- Department of Thoracic SurgeryBeijing Chest HospitalCapital Medical University, Beijing Tuberculosis and Thoracic Tumor Research InstituteBeijingChina
| | - Ping‐Kun Zhou
- Beijing Key Laboratory for RadiobiologyBeijing Institute of Radiation MedicineBeijingChina
| | - Teng Ma
- Cancer Research CenterBeijing Chest HospitalCapital Medical University/Beijing Tuberculosis and Thoracic Tumor Research InstituteBeijingChina
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3
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Mai Y, Lin T, Zhang L, Yang W, Liu S, Wang M, Liu P, Li Z, Luo W. RAD54B inhibits vascular endothelial senescence via suppression of CHK1/p53/p21 pathway. Can J Physiol Pharmacol 2024; 102:137-149. [PMID: 37748205 DOI: 10.1139/cjpp-2023-0192] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/27/2023]
Abstract
RAD54B belongs to the SNF2/SWI2 superfamily, participating in homologous recombination repair. DNA damage is the central driver of aging, but there is no direct evidence of an association between RAD54B and vascular aging. The present study sought to investigate the role and mechanisms of RAD54B in endothelial senescence. In senescent animal models, including spontaneously hypertensive rats, normal aging mice, and D-gal-induced senescent mice, and senescent cell models induced by H2O2, D-gal, and culture, RAD54B was remarkably downregulated. Knockdown of RAD54B increased the expression of p53 and p21, increased the ratio of SA-β-gal-positive cells, and decreased the proportion of EdU-positive cells. Conversely, overexpression of RAD54B reversed the senescent phenotypes stimulated by H2O2 and delayed replicative endothelial senescence. Mechanistically, silencing RAD54B compensatorily increased the expression of RAD51/XRCC4, which remained unchanged in H2O2-induced senescence. RAD54B lacking the SNF2 domain could still reverse the increasing expression of p53/p21 induced by H2O2. RAD54B reduced γH2A.X expression and inhibited the expression and phosphorylation of CHK1. In conclusion, RAD54B exerts a direct protective effect against DNA damage through enhancing homologous recombination repair in endothelial senescence, resulting in inhibition of the downstream CHK1/p53/p21 pathway, suggesting that RAD54B may be a potential therapeutic target for vascular aging-associated diseases.
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Affiliation(s)
- Yanqi Mai
- Laboratory of Pharmacology and Toxicology, School of Pharmaceutical Sciences; National and Local United Engineering Lab of Druggability and New Drugs Evaluation; Guangdong Engineering Laboratory of Druggability and New Drug Evaluation; Guangdong Provincial Key Laboratory of New Drug Design and Evaluation, Sun Yat-sen University, Guangzhou, P. R. China
| | - Tong Lin
- Laboratory of Pharmacology and Toxicology, School of Pharmaceutical Sciences; National and Local United Engineering Lab of Druggability and New Drugs Evaluation; Guangdong Engineering Laboratory of Druggability and New Drug Evaluation; Guangdong Provincial Key Laboratory of New Drug Design and Evaluation, Sun Yat-sen University, Guangzhou, P. R. China
- Department of Pharmacy, Guangdong Provincial People's Hospital (Guangdong Academy of Medical Sciences), Southern Medical University, Guangzhou, P. R. China
| | - Lili Zhang
- Laboratory of Pharmacology and Toxicology, School of Pharmaceutical Sciences; National and Local United Engineering Lab of Druggability and New Drugs Evaluation; Guangdong Engineering Laboratory of Druggability and New Drug Evaluation; Guangdong Provincial Key Laboratory of New Drug Design and Evaluation, Sun Yat-sen University, Guangzhou, P. R. China
| | - Wanqi Yang
- Laboratory of Pharmacology and Toxicology, School of Pharmaceutical Sciences; National and Local United Engineering Lab of Druggability and New Drugs Evaluation; Guangdong Engineering Laboratory of Druggability and New Drug Evaluation; Guangdong Provincial Key Laboratory of New Drug Design and Evaluation, Sun Yat-sen University, Guangzhou, P. R. China
| | - Sitong Liu
- Laboratory of Pharmacology and Toxicology, School of Pharmaceutical Sciences; National and Local United Engineering Lab of Druggability and New Drugs Evaluation; Guangdong Engineering Laboratory of Druggability and New Drug Evaluation; Guangdong Provincial Key Laboratory of New Drug Design and Evaluation, Sun Yat-sen University, Guangzhou, P. R. China
| | - Minghui Wang
- Laboratory of Pharmacology and Toxicology, School of Pharmaceutical Sciences; National and Local United Engineering Lab of Druggability and New Drugs Evaluation; Guangdong Engineering Laboratory of Druggability and New Drug Evaluation; Guangdong Provincial Key Laboratory of New Drug Design and Evaluation, Sun Yat-sen University, Guangzhou, P. R. China
| | - Peiqing Liu
- Laboratory of Pharmacology and Toxicology, School of Pharmaceutical Sciences; National and Local United Engineering Lab of Druggability and New Drugs Evaluation; Guangdong Engineering Laboratory of Druggability and New Drug Evaluation; Guangdong Provincial Key Laboratory of New Drug Design and Evaluation, Sun Yat-sen University, Guangzhou, P. R. China
| | - Zhuoming Li
- Laboratory of Pharmacology and Toxicology, School of Pharmaceutical Sciences; National and Local United Engineering Lab of Druggability and New Drugs Evaluation; Guangdong Engineering Laboratory of Druggability and New Drug Evaluation; Guangdong Provincial Key Laboratory of New Drug Design and Evaluation, Sun Yat-sen University, Guangzhou, P. R. China
| | - Wenwei Luo
- Laboratory of Pharmacology and Toxicology, School of Pharmaceutical Sciences; National and Local United Engineering Lab of Druggability and New Drugs Evaluation; Guangdong Engineering Laboratory of Druggability and New Drug Evaluation; Guangdong Provincial Key Laboratory of New Drug Design and Evaluation, Sun Yat-sen University, Guangzhou, P. R. China
- Department of Pharmacy, Guangdong Provincial People's Hospital (Guangdong Academy of Medical Sciences), Southern Medical University, Guangzhou, P. R. China
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4
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Bader AS, Bushell M. iMUT-seq: high-resolution DSB-induced mutation profiling reveals prevalent homologous-recombination dependent mutagenesis. Nat Commun 2023; 14:8419. [PMID: 38110444 PMCID: PMC10728174 DOI: 10.1038/s41467-023-44167-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Accepted: 12/04/2023] [Indexed: 12/20/2023] Open
Abstract
DNA double-strand breaks (DSBs) are the most mutagenic form of DNA damage, and play a significant role in cancer biology, neurodegeneration and aging. However, studying DSB-induced mutagenesis is limited by our current approaches. Here, we describe iMUT-seq, a technique that profiles DSB-induced mutations at high-sensitivity and single-nucleotide resolution around endogenous DSBs. By depleting or inhibiting 20 DSB-repair factors we define their mutational signatures in detail, revealing insights into the mechanisms of DSB-induced mutagenesis. Notably, we find that homologous-recombination (HR) is more mutagenic than previously thought, inducing prevalent base substitutions and mononucleotide deletions at distance from the break due to DNA-polymerase errors. Simultaneously, HR reduces translocations, suggesting a primary role of HR is specifically the prevention of genomic rearrangements. The results presented here offer fundamental insights into DSB-induced mutagenesis and have significant implications for our understanding of cancer biology and the development of DDR-targeting chemotherapeutics.
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Affiliation(s)
- Aldo S Bader
- Cancer Research UK Beatson Institute, Glasgow, G61 1BD, UK.
- Cancer Research UK/CI, University of Cambridge, Li Ka Shing Centre, Cambridge, CB2 0RE, UK.
- The Gurdon Institute, University of Cambridge, Biochemistry, Cambridge, UK.
| | - Martin Bushell
- Cancer Research UK Beatson Institute, Glasgow, G61 1BD, UK.
- Institute of Cancer Sciences, University of Glasgow, Glasgow, G61 1QH, UK.
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5
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Loparo JJ. Holding it together: DNA end synapsis during non-homologous end joining. DNA Repair (Amst) 2023; 130:103553. [PMID: 37572577 PMCID: PMC10530278 DOI: 10.1016/j.dnarep.2023.103553] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2023] [Revised: 08/04/2023] [Accepted: 08/06/2023] [Indexed: 08/14/2023]
Abstract
DNA double strand breaks (DSBs) are common lesions whose misrepair are drivers of oncogenic transformations. The non-homologous end joining (NHEJ) pathway repairs the majority of these breaks in vertebrates by directly ligating DNA ends back together. Upon formation of a DSB, a multiprotein complex is assembled on DNA ends which tethers them together within a synaptic complex. Synapsis is a critical step of the NHEJ pathway as loss of synapsis can result in mispairing of DNA ends and chromosome translocations. As DNA ends are commonly incompatible for ligation, the NHEJ machinery must also process ends to enable rejoining. This review describes how recent progress in single-molecule approaches and cryo-EM have advanced our molecular understanding of DNA end synapsis during NHEJ and how synapsis is coordinated with end processing to determine the fidelity of repair.
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Affiliation(s)
- Joseph J Loparo
- Dept. of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA.
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6
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Shridharan RV, Kalakuntla N, Chirmule N, Tiwari B. The Happy Hopping of Transposons: The Origins of V(D)J Recombination in Adaptive Immunity. Front Ecol Evol 2022. [DOI: 10.3389/fevo.2022.836066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Nearly 50% of the human genome is derived from transposable elements (TEs). Though dysregulated transposons are deleterious to humans and can lead to diseases, co-opted transposons play an important role in generating alternative or new DNA sequence combinations to perform novel cellular functions. The appearance of an adaptive immune system in jawed vertebrates, wherein the somatic rearrangement of T and B cells generates a repertoire of antibodies and receptors, is underpinned by Class II TEs. This review follows the evolution of recombination activation genes (RAGs), components of adaptive immunity, from TEs, focusing on the structural and mechanistic similarities between RAG recombinases and DNA transposases. As evolution occurred from a transposon precursor, DNA transposases developed a more targeted and constrained mechanism of mobilization. As DNA repair is integral to transposition and recombination, we note key similarities and differences in the choice of DNA repair pathways following these processes. Understanding the regulation of V(D)J recombination from its evolutionary origins may help future research to specifically target RAG proteins to rectify diseases associated with immune dysregulation.
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7
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Christie SM, Fijen C, Rothenberg E. V(D)J Recombination: Recent Insights in Formation of the Recombinase Complex and Recruitment of DNA Repair Machinery. Front Cell Dev Biol 2022; 10:886718. [PMID: 35573672 PMCID: PMC9099191 DOI: 10.3389/fcell.2022.886718] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Accepted: 04/01/2022] [Indexed: 11/13/2022] Open
Abstract
V(D)J recombination is an essential mechanism of the adaptive immune system, producing a diverse set of antigen receptors in developing lymphocytes via regulated double strand DNA break and subsequent repair. DNA cleavage is initiated by the recombinase complex, consisting of lymphocyte specific proteins RAG1 and RAG2, while the repair phase is completed by classical non-homologous end joining (NHEJ). Many of the individual steps of this process have been well described and new research has increased the scale to understand the mechanisms of initiation and intermediate stages of the pathway. In this review we discuss 1) the regulatory functions of RAGs, 2) recruitment of RAGs to the site of recombination and formation of a paired complex, 3) the transition from a post-cleavage complex containing RAGs and cleaved DNA ends to the NHEJ repair phase, and 4) the potential redundant roles of certain factors in repairing the break. Regulatory (non-core) domains of RAGs are not necessary for catalytic activity, but likely influence recruitment and stabilization through interaction with modified histones and conformational changes. To form long range paired complexes, recent studies have found evidence in support of large scale chromosomal contraction through various factors to utilize diverse gene segments. Following the paired cleavage event, four broken DNA ends must now make a regulated transition to the repair phase, which can be controlled by dynamic conformational changes and post-translational modification of the factors involved. Additionally, we examine the overlapping roles of certain NHEJ factors which allows for prevention of genomic instability due to incomplete repair in the absence of one, but are lethal in combined knockouts. To conclude, we focus on the importance of understanding the detail of these processes in regards to off-target recombination or deficiency-mediated clinical manifestations.
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Affiliation(s)
- Shaun M. Christie
- *Correspondence: Shaun M. Christie, ; Carel Fijen, ; Eli Rothenberg,
| | - Carel Fijen
- *Correspondence: Shaun M. Christie, ; Carel Fijen, ; Eli Rothenberg,
| | - Eli Rothenberg
- *Correspondence: Shaun M. Christie, ; Carel Fijen, ; Eli Rothenberg,
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8
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McPherson KS, Korzhnev DM. Targeting protein-protein interactions in the DNA damage response pathways for cancer chemotherapy. RSC Chem Biol 2021; 2:1167-1195. [PMID: 34458830 PMCID: PMC8342002 DOI: 10.1039/d1cb00101a] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2021] [Accepted: 06/20/2021] [Indexed: 12/11/2022] Open
Abstract
Cellular DNA damage response (DDR) is an extensive signaling network that orchestrates DNA damage recognition, repair and avoidance, cell cycle progression and cell death. DDR alteration is a hallmark of cancer, with the deficiency in one DDR capability often compensated by a dependency on alternative pathways endowing cancer cells with survival and growth advantage. Targeting these DDR pathways has provided multiple opportunities for the development of cancer therapies. Traditional drug discovery has mainly focused on catalytic inhibitors that block enzyme active sites, which limits the number of potential drug targets within the DDR pathways. This review article describes the emerging approach to the development of cancer therapeutics targeting essential protein-protein interactions (PPIs) in the DDR network. The overall strategy for the structure-based design of small molecule PPI inhibitors is discussed, followed by an overview of the major DNA damage sensing, DNA repair, and DNA damage tolerance pathways with a specific focus on PPI targets for anti-cancer drug design. The existing small molecule inhibitors of DDR PPIs are summarized that selectively kill cancer cells and/or sensitize cancers to front-line genotoxic therapies, and a range of new PPI targets are proposed that may lead to the development of novel chemotherapeutics.
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Affiliation(s)
- Kerry Silva McPherson
- Department of Molecular Biology and Biophysics, University of Connecticut Health Center Farmington CT 06030 USA +1 860 679 3408 +1 860 679 2849
| | - Dmitry M Korzhnev
- Department of Molecular Biology and Biophysics, University of Connecticut Health Center Farmington CT 06030 USA +1 860 679 3408 +1 860 679 2849
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9
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Jensen RB, Rothenberg E. Preserving genome integrity in human cells via DNA double-strand break repair. Mol Biol Cell 2021; 31:859-865. [PMID: 32286930 PMCID: PMC7185975 DOI: 10.1091/mbc.e18-10-0668] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The efficient maintenance of genome integrity in the face of cellular stress is vital to protect against human diseases such as cancer. DNA replication, chromatin dynamics, cellular signaling, nuclear architecture, cell cycle checkpoints, and other cellular activities contribute to the delicate spatiotemporal control that cells utilize to regulate and maintain genome stability. This perspective will highlight DNA double-strand break (DSB) repair pathways in human cells, how DNA repair failures can lead to human disease, and how PARP inhibitors have emerged as a novel clinical therapy to treat homologous recombination-deficient tumors. We briefly discuss how failures in DNA repair produce a permissive genetic environment in which preneoplastic cells evolve to reach their full tumorigenic potential. Finally, we conclude that an in-depth understanding of DNA DSB repair pathways in human cells will lead to novel therapeutic strategies to treat cancer and potentially other human diseases.
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Affiliation(s)
- Ryan B Jensen
- Department of Therapeutic Radiology, Yale University School of Medicine, New Haven, CT 06520-8040
| | - Eli Rothenberg
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY 10016
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10
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Asa ADDC, Wanotayan R, Sharma MK, Tsukada K, Shimada M, Matsumoto Y. Functional analysis of XRCC4 mutations in reported microcephaly and growth defect patients in terms of radiosensitivity. JOURNAL OF RADIATION RESEARCH 2021; 62:380-389. [PMID: 33842963 PMCID: PMC8127669 DOI: 10.1093/jrr/rrab016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2020] [Revised: 02/01/2021] [Indexed: 05/08/2023]
Abstract
Non-homologous end joining is one of the main pathways for DNA double-strand break (DSB) repair and is also implicated in V(D)J recombination in immune system. Therefore, mutations in non-homologous end-joining (NHEJ) proteins were found to be associated with immunodeficiency in human as well as in model animals. Several human patients with mutations in XRCC4 were reported to exhibit microcephaly and growth defects, but unexpectedly showed normal immune function. Here, to evaluate the functionality of these disease-associated mutations of XRCC4 in terms of radiosensitivity, we generated stable transfectants expressing these mutants in XRCC4-deficient murine M10 cells and measured their radiosensitivity by colony formation assay. V83_S105del, R225X and D254Mfs*68 were expressed at a similar level to wild-type XRCC4, while W43R, R161Q and R275X were expressed at even higher level than wild-type XRCC4. The expression levels of DNA ligase IV in the transfectants with these mutants were comparable to that in the wild-type XRCC4 transfectant. The V83S_S105del transfectant and, to a lesser extent, D254Mfs*68 transfectant, showed substantially increased radiosensitivity compared to the wild-type XRCC4 transfectant. The W43R, R161Q, R225X and R275X transfectants showed a slight but statistically significant increase in radiosensitivity compared to the wild-type XRCC4 transfectant. When expressed as fusion proteins with Green fluorescent protein (GFP), R225X, R275X and D254Mfs*68 localized to the cytoplasm, whereas other mutants localized to the nucleus. These results collectively indicated that the defects of XRCC4 in patients might be mainly due to insufficiency in protein quantity and impaired functionality, underscoring the importance of XRCC4's DSB repair function in normal development.
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Affiliation(s)
- Anie Day D C Asa
- Laboratory for Advanced Nuclear Energy, Institute of Innovative Research, Tokyo Institute of Technology, Tokyo 152-8550, Japan
| | - Rujira Wanotayan
- Laboratory for Advanced Nuclear Energy, Institute of Innovative Research, Tokyo Institute of Technology, Tokyo 152-8550, Japan
- Department of Radiological Technology, Mahidol University, Nakhon Pathom 73170, Thailand
| | - Mukesh Kumar Sharma
- Laboratory for Advanced Nuclear Energy, Institute of Innovative Research, Tokyo Institute of Technology, Tokyo 152-8550, Japan
- Department of Zoology, SPC Government College, Ajmer-305001, Rajasthan, India
| | - Kaima Tsukada
- Laboratory for Advanced Nuclear Energy, Institute of Innovative Research, Tokyo Institute of Technology, Tokyo 152-8550, Japan
| | - Mikio Shimada
- Laboratory for Advanced Nuclear Energy, Institute of Innovative Research, Tokyo Institute of Technology, Tokyo 152-8550, Japan
| | - Yoshihisa Matsumoto
- Corresponding author. Yoshihisa Matsumoto, Laboratory for Advanced Nuclear Energy, Institute of Innovative Research, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550 Japan. E-mail: ; FAX: +81-3-5734-3703
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11
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Stinson BM, Loparo JJ. Repair of DNA Double-Strand Breaks by the Nonhomologous End Joining Pathway. Annu Rev Biochem 2021; 90:137-164. [PMID: 33556282 DOI: 10.1146/annurev-biochem-080320-110356] [Citation(s) in RCA: 85] [Impact Index Per Article: 28.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
DNA double-strand breaks pose a serious threat to genome stability. In vertebrates, these breaks are predominantly repaired by nonhomologous end joining (NHEJ), which pairs DNA ends in a multiprotein synaptic complex to promote their direct ligation. NHEJ is a highly versatile pathway that uses an array of processing enzymes to modify damaged DNA ends and enable their ligation. The mechanisms of end synapsis and end processing have important implications for genome stability. Rapid and stable synapsis is necessary to limit chromosome translocations that result from the mispairing of DNA ends. Furthermore, end processing must be tightly regulated to minimize mutations at the break site. Here, we review our current mechanistic understanding of vertebrate NHEJ, with a particular focus on end synapsis and processing.
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Affiliation(s)
- Benjamin M Stinson
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts 02115, USA; ,
| | - Joseph J Loparo
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts 02115, USA; ,
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12
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Carney SM, Moreno AT, Piatt SC, Cisneros-Aguirre M, Lopezcolorado FW, Stark JM, Loparo JJ. XLF acts as a flexible connector during non-homologous end joining. eLife 2020; 9:e61920. [PMID: 33289484 PMCID: PMC7744095 DOI: 10.7554/elife.61920] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2020] [Accepted: 12/07/2020] [Indexed: 01/01/2023] Open
Abstract
Non-homologous end joining (NHEJ) is the predominant pathway that repairs DNA double-strand breaks in vertebrates. During NHEJ DNA ends are held together by a multi-protein synaptic complex until they are ligated. Here, we use Xenopus laevis egg extract to investigate the role of the intrinsically disordered C-terminal tail of the XRCC4-like factor (XLF), a critical factor in end synapsis. We demonstrate that the XLF tail along with the Ku-binding motif (KBM) at the extreme C-terminus are required for end joining. Although the underlying sequence of the tail can be varied, a minimal tail length is required for NHEJ. Single-molecule FRET experiments that observe end synapsis in real-time show that this defect is due to a failure to closely align DNA ends. Our data supports a model in which a single C-terminal tail tethers XLF to Ku, while allowing XLF to form interactions with XRCC4 that enable synaptic complex formation.
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Affiliation(s)
- Sean M Carney
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical SchoolBostonUnited States
| | - Andrew T Moreno
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical SchoolBostonUnited States
| | - Sadie C Piatt
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical SchoolBostonUnited States
- Harvard Graduate Program in Biophysics, Harvard Medical SchoolBostonUnited States
| | - Metztli Cisneros-Aguirre
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute of the City of HopeDuarteUnited States
- Irell and Manella Graduate School of Biological Sciences, Beckman Research Institute of the City of HopeDuarteUnited States
| | | | - Jeremy M Stark
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute of the City of HopeDuarteUnited States
- Irell and Manella Graduate School of Biological Sciences, Beckman Research Institute of the City of HopeDuarteUnited States
| | - Joseph J Loparo
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical SchoolBostonUnited States
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13
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Meek K. Activation of DNA-PK by hairpinned DNA ends reveals a stepwise mechanism of kinase activation. Nucleic Acids Res 2020; 48:9098-9108. [PMID: 32716029 PMCID: PMC7498359 DOI: 10.1093/nar/gkaa614] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Revised: 07/08/2020] [Accepted: 07/14/2020] [Indexed: 12/12/2022] Open
Abstract
As its name implies, the DNA dependent protein kinase (DNA-PK) requires DNA double-stranded ends for enzymatic activation. Here, I demonstrate that hairpinned DNA ends are ineffective for activating the kinase toward many of its well-studied substrates (p53, XRCC4, XLF, HSP90). However, hairpinned DNA ends robustly stimulate certain DNA-PK autophosphorylations. Specifically, autophosphorylation sites within the ABCDE cluster are robustly phosphorylated when DNA-PK is activated by hairpinned DNA ends. Of note, phosphorylation of the ABCDE sites is requisite for activation of the Artemis nuclease that associates with DNA-PK to mediate hairpin opening. This finding suggests a multi-step mechanism of kinase activation. Finally, I find that all non-homologous end joining (NHEJ) defective cells (whether deficient in components of the DNA-PK complex or components of the ligase complex) are similarly deficient in joining DNA double-stranded breaks (DSBs) with hairpinned termini.
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Affiliation(s)
- Katheryn Meek
- Department of Microbiology & Molecular Genetics, and Department of Pathobiology & Diagnostic Investigation, College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824, USA
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14
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Neal JA, Dunger K, Geith K, Meek K. Deciphering the role of distinct DNA-PK phosphorylations at collapsed replication forks. DNA Repair (Amst) 2020; 94:102925. [PMID: 32674014 PMCID: PMC7494621 DOI: 10.1016/j.dnarep.2020.102925] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Revised: 06/29/2020] [Accepted: 07/06/2020] [Indexed: 11/29/2022]
Abstract
It has recently been established that the marked sensitivity of ATM deficient cells to topoisomerase poisons like camptothecin (Cpt) results from unrestrained end-joining of DNA ends at collapsed replication forks that is mediated by the non-homologous end joining [NHEJ] pathway and results in the induction of copious numbers of genomic alterations, termed "toxic NHEJ". Ablation of core components of the NHEJ pathway reverses the Cpt sensitivity of ATM deficient cells, but inhibition of DNA-PKcs does not. Here, we show that complete ablation of DNA-PKcs partially reverses the Cpt sensitivity of ATM deficient cells; thus, ATM deficient cells lacking DNA-PKcs are more resistant to Cpt than cells expressing DNA-PKcs. However, the relative sensitivity of DNA-PKcs proficient ATM deficient cells is inversely proportional to DNA-PKcs expression levels. These data suggest that DNA-PK may phosphorylate an ATM target (that contributes to Cpt resistance), explaining partial rescue of Cpt sensitivity in cells expressing high levels of DNA-PKcs. Although crippling NHEJ function by mutagenic blockade of the critical ABCDE autophosphorylation sites in DNA-PKcs also sensitizes cells to Cpt, this sensitization apparently occurs by a distinct mechanism from ATM ablation because blockade of these sites actually rescues ATM deficient cells from toxic NHEJ. These data are consistent with autophosphorylation of the ABCDE sites (and not ATM mediated phosphorylation) in response to Cpt-induced damage. In contrast, blockade of S3205 (an ATM dependent phosphorylation site in DNA-PKcs) that minimally impacts NHEJ, increases Cpt sensitivity. In sum, these data suggest that ATM and DNA-PK cooperate to facilitate Cpt-induced DNA damage, and that ATM phosphorylation of S3205 facilitates appropriate repair at collapsed replication forks.
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Affiliation(s)
- Jessica A Neal
- College of Veterinary Medicine, Department of Microbiology & Molecular Genetics, Department of Pathobiology & Diagnostic Investigation, Michigan State University, East Lansing, MI 48824, USA
| | - Krista Dunger
- College of Veterinary Medicine, Department of Microbiology & Molecular Genetics, Department of Pathobiology & Diagnostic Investigation, Michigan State University, East Lansing, MI 48824, USA
| | - Kelly Geith
- College of Veterinary Medicine, Department of Microbiology & Molecular Genetics, Department of Pathobiology & Diagnostic Investigation, Michigan State University, East Lansing, MI 48824, USA
| | - Katheryn Meek
- College of Veterinary Medicine, Department of Microbiology & Molecular Genetics, Department of Pathobiology & Diagnostic Investigation, Michigan State University, East Lansing, MI 48824, USA.
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15
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Britton S, Chanut P, Delteil C, Barboule N, Frit P, Calsou P. ATM antagonizes NHEJ proteins assembly and DNA-ends synapsis at single-ended DNA double strand breaks. Nucleic Acids Res 2020; 48:9710-9723. [PMID: 32890395 PMCID: PMC7515714 DOI: 10.1093/nar/gkaa723] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Revised: 07/29/2020] [Accepted: 08/21/2020] [Indexed: 12/15/2022] Open
Abstract
Two DNA repair pathways operate at DNA double strand breaks (DSBs): non-homologous end-joining (NHEJ), that requires two adjacent DNA ends for ligation, and homologous recombination (HR), that resects one DNA strand for invasion of a homologous duplex. Faithful repair of replicative single-ended DSBs (seDSBs) is mediated by HR, due to the lack of a second DNA end for end-joining. ATM stimulates resection at such breaks through multiple mechanisms including CtIP phosphorylation, which also promotes removal of the DNA-ends sensor and NHEJ protein Ku. Here, using a new method for imaging the recruitment of the Ku partner DNA-PKcs at DSBs, we uncover an unanticipated role of ATM in removing DNA-PKcs from seDSBs in human cells. Phosphorylation of DNA-PKcs on the ABCDE cluster is necessary not only for DNA-PKcs clearance but also for the subsequent MRE11/CtIP-dependent release of Ku from these breaks. We propose that at seDSBs, ATM activity is necessary for the release of both Ku and DNA-PKcs components of the NHEJ apparatus, and thereby prevents subsequent aberrant interactions between seDSBs accompanied by DNA-PKcs autophosphorylation and detrimental commitment to Lig4-dependent end-joining.
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Affiliation(s)
- Sébastien Britton
- Institut de Pharmacologie et de Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS, Toulouse, France
- Equipe Labellisée Ligue contre le Cancer 2018, Toulouse, France
| | - Pauline Chanut
- Institut de Pharmacologie et de Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS, Toulouse, France
- Equipe Labellisée Ligue contre le Cancer 2018, Toulouse, France
| | - Christine Delteil
- Institut de Pharmacologie et de Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS, Toulouse, France
- Equipe Labellisée Ligue contre le Cancer 2018, Toulouse, France
| | - Nadia Barboule
- Institut de Pharmacologie et de Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS, Toulouse, France
- Equipe Labellisée Ligue contre le Cancer 2018, Toulouse, France
| | - Philippe Frit
- Institut de Pharmacologie et de Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS, Toulouse, France
- Equipe Labellisée Ligue contre le Cancer 2018, Toulouse, France
| | - Patrick Calsou
- Institut de Pharmacologie et de Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS, Toulouse, France
- Equipe Labellisée Ligue contre le Cancer 2018, Toulouse, France
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16
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Structural mechanism of DNA-end synapsis in the non-homologous end joining pathway for repairing double-strand breaks: bridge over troubled ends. Biochem Soc Trans 2020; 47:1609-1619. [PMID: 31829407 DOI: 10.1042/bst20180518] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Revised: 11/25/2019] [Accepted: 11/27/2019] [Indexed: 12/18/2022]
Abstract
Non-homologous end joining (NHEJ) is a major repair pathway for DNA double-strand breaks (DSBs), which is the most toxic DNA damage in cells. Unrepaired DSBs can cause genome instability, tumorigenesis or cell death. DNA end synapsis is the first and probably the most important step of the NHEJ pathway, aiming to bring two broken DNA ends close together and provide structural stability for end processing and ligation. This process is mediated through a group of NHEJ proteins forming higher-order complexes, to recognise and bridge two DNA ends. Spatial and temporal understanding of the structural mechanism of DNA-end synapsis has been largely advanced through recent structural and single-molecule studies of NHEJ proteins. This review focuses on core NHEJ proteins that mediate DNA end synapsis through their unique structures and interaction properties, as well as how they play roles as anchor and linker proteins during the process of 'bridge over troubled ends'.
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17
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Ruis B, Molan A, Takasugi T, Hendrickson EA. Absence of XRCC4 and its paralogs in human cells reveal differences in outcomes for DNA repair and V(D)J recombination. DNA Repair (Amst) 2019; 85:102738. [PMID: 31731258 DOI: 10.1016/j.dnarep.2019.102738] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2019] [Revised: 10/15/2019] [Accepted: 10/16/2019] [Indexed: 02/06/2023]
Abstract
The repair of DNA double-stranded breaks (DSBs) is an essential function performed by the Classical Non-Homologous End-Joining (C-NHEJ) pathway in higher eukaryotes. C-NHEJ, in fact, does double duty as it is also required for the repair of the intermediates formed during lymphoid B- and T-cell recombination. Consequently, the failure to properly repair DSBs leads to both genomic instability and immunodeficiency. A critical DSB protein required for C-NHEJ is the DNA Ligase IV (LIGIV) accessory factor, X-Ray Cross Complementing 4 (XRCC4). XRCC4 is believed to stabilize LIGIV, participate in LIGIV activation, and to help tether the broken DSB ends together. XRCC4's role in these processes has been muddied by the identification of two additional XRCC4 paralogs, XRCC4-Like Factor (XLF), and Paralog of XRCC4 and XLF (PAXX). The roles that these paralogs play in C-NHEJ is partially understood, but, in turn, has itself been obscured by species-specific differences observed in the absence of one or the other paralogs. In order to investigate the role(s) that XRCC4 may play, with or without XLF and/or PAXX, in lymphoid variable(diversity)joining [V(D)J] recombination as well as in DNA DSB repair in human somatic cells, we utilized gene targeting to inactivate the XRCC4 gene in both parental and XLF- HCT116 cells and then inactivated PAXX in those same cell lines. The loss of XRCC4 expression by itself led, as anticipated, to increased sensitivity to DNA damaging agents as well as an increased dependence on microhomology-mediated DNA repair whether in the context of DSB repair or during V(D)J recombination. The additional loss of XLF in these cell lines sensitized the cells even more whereas the presence or absence of PAXX was scarcely negligible. These studies demonstrate that, of the three LIG4 accessory factor paralogs, the absence of XRCC4 influences DNA repair and recombination the most in human cells.
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Affiliation(s)
- Brian Ruis
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota Medical School, Minneapolis, MN, 55455, United States
| | - Amy Molan
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota Medical School, Minneapolis, MN, 55455, United States
| | - Taylor Takasugi
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota Medical School, Minneapolis, MN, 55455, United States
| | - Eric A Hendrickson
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota Medical School, Minneapolis, MN, 55455, United States.
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18
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Plugged into the Ku-DNA hub: The NHEJ network. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2019; 147:62-76. [PMID: 30851288 DOI: 10.1016/j.pbiomolbio.2019.03.001] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2018] [Revised: 02/26/2019] [Accepted: 03/01/2019] [Indexed: 12/16/2022]
Abstract
In vertebrates, double-strand breaks in DNA are primarily repaired by Non-Homologous End-Joining (NHEJ). The ring-shaped Ku heterodimer rapidly senses and threads onto broken DNA ends forming a recruiting hub. Through protein-protein contacts eventually reinforced by protein-DNA interactions, the Ku-DNA hub attracts a series of specialized proteins with scaffolding and/or enzymatic properties. To shed light on these dynamic interplays, we review here current knowledge on proteins directly interacting with Ku and on the contact points involved, with a particular accent on the different classes of Ku-binding motifs identified in several Ku partners. An integrated structural model of the core NHEJ network at the synapsis step is proposed.
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19
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Neal JA, Meek K. Deciphering phenotypic variance in different models of DNA-PKcs deficiency. DNA Repair (Amst) 2018; 73:7-16. [PMID: 30409670 DOI: 10.1016/j.dnarep.2018.10.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Revised: 10/09/2018] [Accepted: 10/14/2018] [Indexed: 02/02/2023]
Abstract
DNA-PKcs deficiency has been studied in numerous animal models and cell culture systems. In previous studies of kinase inactivating mutations in cell culture systems, ablation of DNA-PK's catalytic activity results in a cell phenotype that is virtually indistinguishable from that ascribed to complete loss of the enzyme. However, a recent compelling study demonstrates a remarkably more severe phenotype in mice harboring a targeted disruption of DNA-PK's ATP binding site as compared to DNA-PKcs deficient mice. Here we investigate the mechanism for these divergent results. We find that kinase inactivating DNA-PKcs mutants markedly radiosensitize immortalized DNA-PKcs deficient cells, but have no substantial effects on transformed DNA-PKcs deficient cells. Since the non-homologous end joining mechanism likely functions similarly in all of these cell strains, it seems unlikely that kinase inactive DNA-PK could impair the end joining mechanism in some cell types, but not in others. In fact, we observed no significant differences in either episomal or chromosomal end joining assays in cells expressing kinase inactivated DNA-PKcs versus no DNA-PKcs. Several potential explanations could explain these data including a non-catalytic role for DNA-PKcs in promoting cell death, or alteration of gene expression by loss of DNA-PKcs as opposed to inhibition of its catalytic activity. Finally, controversy exists as to whether DNA-PKcs autophosphorylates or is the target of other PIKKs; we present data demonstrating that DNA-PK primarily autophosphorylates.
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Affiliation(s)
- Jessica A Neal
- College of Veterinary Medicine, Department of Microbiology & Molecular Genetics, and Department of Pathobiology & Diagnostic Investigation, Michigan State University, East Lansing, MI 48824, USA
| | - Katheryn Meek
- College of Veterinary Medicine, Department of Microbiology & Molecular Genetics, and Department of Pathobiology & Diagnostic Investigation, Michigan State University, East Lansing, MI 48824, USA.
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20
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A single XLF dimer bridges DNA ends during nonhomologous end joining. Nat Struct Mol Biol 2018; 25:877-884. [PMID: 30177755 PMCID: PMC6128732 DOI: 10.1038/s41594-018-0120-y] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Accepted: 07/05/2018] [Indexed: 01/09/2023]
Abstract
Non-homologous end joining (NHEJ) is the primary pathway of DNA double-strand break repair in vertebrate cells, yet it remains unclear how NHEJ factors assemble a synaptic complex that bridges DNA ends. To address the role of XRCC4-like factor (XLF) in synaptic complex assembly, we employed single-molecule fluorescence imaging in Xenopus laevis egg extract, a system that efficiently joins DNA ends. We find that a single XLF dimer binds to DNA substrates just prior to formation of a ligation-competent synaptic complex between DNA ends. The interaction of both globular head domains of the XLF dimer with XRCC4 is required for efficient formation of this synaptic complex. In contrast to a model in which filaments of XLF and XRCC4 bridge DNA ends, our results indicate that binding of a single XLF dimer facilitates the assembly of a stoichiometrically well-defined synaptic complex.
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21
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Fritzen D, Kuechler A, Grimmel M, Becker J, Peters S, Sturm M, Hundertmark H, Schmidt A, Kreiß M, Strom TM, Wieczorek D, Haack TB, Beck-Wödl S, Cremer K, Engels H. De novo FBXO11 mutations are associated with intellectual disability and behavioural anomalies. Hum Genet 2018; 137:401-411. [PMID: 29796876 DOI: 10.1007/s00439-018-1892-1] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2018] [Accepted: 05/17/2018] [Indexed: 12/26/2022]
Abstract
Intellectual disability (ID) has an estimated prevalence of 1.5-2%. In most affected individuals, its genetic basis remains unclear. Whole exome sequencing (WES) studies have identified a multitude of novel causative gene defects and have shown that a large proportion of sporadic ID cases results from de novo mutations. Here, we present two unrelated individuals with similar clinical features and deleterious de novo variants in FBXO11 detected by WES. Individual 1, a 14-year-old boy, has mild ID as well as mild microcephaly, corrected cleft lip and alveolus, hyperkinetic disorder, mild brain atrophy and minor facial dysmorphism. WES detected a heterozygous de novo 1 bp insertion in the splice donor site of exon 3. Individual 2, a 3-year-old boy, showed ID and pre- and postnatal growth retardation, postnatal mild microcephaly, hyperkinetic and restless behaviour, as well as mild dysmorphism. WES detected a heterozygous de novo frameshift mutation. While ten individuals with ID and de novo variants in FBXO11 have been reported as part of larger studies, only one of the reports has some additional clinical data. Interestingly, the latter individual carries the identical mutation as our individual 2 and also displays ID, intrauterine growth retardation, microcephaly, behavioural anomalies, and dysmorphisms. Thus, we confirm deleterious de novo mutations in FBXO11 as a cause of ID and start the delineation of the associated clinical picture which may also comprise postnatal microcephaly or borderline small head size and behavioural anomalies.
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Affiliation(s)
- Daniel Fritzen
- Institute of Human Genetics, University of Bonn, School of Medicine & University Hospital Bonn, Sigmund-Freud-Str. 25, 53127, Bonn, Germany
| | - Alma Kuechler
- Institut für Humangenetik, Universitätsklinikum Essen, Universität Duisburg-Essen, Hufelandstraße 55, 45147, Essen, Germany
| | - Mona Grimmel
- Institute of Medical Genetics and Applied Genomics, University of Tübingen, Calwerstrasse 7, 72076, Tübingen, Germany
| | - Jessica Becker
- Institute of Human Genetics, University of Bonn, School of Medicine & University Hospital Bonn, Sigmund-Freud-Str. 25, 53127, Bonn, Germany
| | - Sophia Peters
- Institute of Human Genetics, University of Bonn, School of Medicine & University Hospital Bonn, Sigmund-Freud-Str. 25, 53127, Bonn, Germany
| | - Marc Sturm
- Institute of Medical Genetics and Applied Genomics, University of Tübingen, Calwerstrasse 7, 72076, Tübingen, Germany
| | - Hela Hundertmark
- Institute of Human Genetics, University of Bonn, School of Medicine & University Hospital Bonn, Sigmund-Freud-Str. 25, 53127, Bonn, Germany
| | - Axel Schmidt
- Institute of Human Genetics, University of Bonn, School of Medicine & University Hospital Bonn, Sigmund-Freud-Str. 25, 53127, Bonn, Germany
| | - Martina Kreiß
- Institute of Human Genetics, University of Bonn, School of Medicine & University Hospital Bonn, Sigmund-Freud-Str. 25, 53127, Bonn, Germany
| | - Tim M Strom
- Institute of Human Genetics, Helmholtz Zentrum München, Ingolstaedter Landstr. 1, 85764, Neuherberg, Germany
- Institute of Human Genetics, Technische Universität München, Trogerstraße 32, 81675, München, Germany
| | - Dagmar Wieczorek
- Institut für Humangenetik, Universitätsklinikum Essen, Universität Duisburg-Essen, Hufelandstraße 55, 45147, Essen, Germany
- Heinrich-Heine-University, Medical Faculty, Institute of Human Genetics, Universitätsstr. 1, 40225, Düsseldorf, Germany
| | - Tobias B Haack
- Institute of Medical Genetics and Applied Genomics, University of Tübingen, Calwerstrasse 7, 72076, Tübingen, Germany
- Institute of Human Genetics, Technische Universität München, Trogerstraße 32, 81675, München, Germany
| | - Stefanie Beck-Wödl
- Institute of Medical Genetics and Applied Genomics, University of Tübingen, Calwerstrasse 7, 72076, Tübingen, Germany
| | - Kirsten Cremer
- Institute of Human Genetics, University of Bonn, School of Medicine & University Hospital Bonn, Sigmund-Freud-Str. 25, 53127, Bonn, Germany
| | - Hartmut Engels
- Institute of Human Genetics, University of Bonn, School of Medicine & University Hospital Bonn, Sigmund-Freud-Str. 25, 53127, Bonn, Germany.
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22
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Che R, Zhang J, Nepal M, Han B, Fei P. Multifaceted Fanconi Anemia Signaling. Trends Genet 2018; 34:171-183. [PMID: 29254745 PMCID: PMC5858900 DOI: 10.1016/j.tig.2017.11.006] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Accepted: 11/28/2017] [Indexed: 01/26/2023]
Abstract
In 1927 Guido Fanconi described a hereditary condition presenting panmyelopathy accompanied by short stature and hyperpigmentation, now better known as Fanconi anemia (FA). With this discovery the genetic and molecular basis underlying FA has emerged as a field of great interest. FA signaling is crucial in the DNA damage response (DDR) to mediate the repair of damaged DNA. This has attracted a diverse range of investigators, especially those interested in aging and cancer. However, recent evidence suggests FA signaling also regulates functions outside the DDR, with implications for many other frontiers of research. We discuss here the characteristics of FA functions and expand upon current perspectives regarding the genetics of FA, indicating that FA plays a role in a myriad of molecular and cellular processes.
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Affiliation(s)
- Raymond Che
- University of Hawaii Cancer Center, University of Hawaii, Honolulu, HI, USA; Graduate Program of Molecular Biosciences and Bioengineering, University of Hawaii, Honolulu, HI, USA
| | - Jun Zhang
- Department of Laboratory Medicine and Pathology, Mayo Clinic Foundation, USA
| | - Manoj Nepal
- University of Hawaii Cancer Center, University of Hawaii, Honolulu, HI, USA; Graduate Program of Molecular Biosciences and Bioengineering, University of Hawaii, Honolulu, HI, USA
| | - Bing Han
- University of Hawaii Cancer Center, University of Hawaii, Honolulu, HI, USA
| | - Peiwen Fei
- University of Hawaii Cancer Center, University of Hawaii, Honolulu, HI, USA; Graduate Program of Molecular Biosciences and Bioengineering, University of Hawaii, Honolulu, HI, USA.
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23
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Aceytuno RD, Piett CG, Havali-Shahriari Z, Edwards RA, Rey M, Ye R, Javed F, Fang S, Mani R, Weinfeld M, Hammel M, Tainer JA, Schriemer DC, Lees-Miller SP, Glover JNM. Structural and functional characterization of the PNKP-XRCC4-LigIV DNA repair complex. Nucleic Acids Res 2017; 45:6238-6251. [PMID: 28453785 PMCID: PMC5449630 DOI: 10.1093/nar/gkx275] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Accepted: 04/25/2017] [Indexed: 01/14/2023] Open
Abstract
Non-homologous end joining (NHEJ) repairs DNA double strand breaks in non-cycling eukaryotic cells. NHEJ relies on polynucleotide kinase/phosphatase (PNKP), which generates 5΄-phosphate/3΄-hydroxyl DNA termini that are critical for ligation by the NHEJ DNA ligase, LigIV. PNKP and LigIV require the NHEJ scaffolding protein, XRCC4. The PNKP FHA domain binds to the CK2-phosphorylated XRCC4 C-terminal tail, while LigIV uses its tandem BRCT repeats to bind the XRCC4 coiled-coil. Yet, the assembled PNKP-XRCC4–LigIV complex remains uncharacterized. Here, we report purification and characterization of a recombinant PNKP–XRCC4–LigIV complex. We show that the stable binding of PNKP in this complex requires XRCC4 phosphorylation and that only one PNKP protomer binds per XRCC4 dimer. Small angle X-ray scattering (SAXS) reveals a flexible multi-state complex that suggests that both the PNKP FHA and catalytic domains contact the XRCC4 coiled-coil and LigIV BRCT repeats. Hydrogen-deuterium exchange indicates protection of a surface on the PNKP phosphatase domain that may contact XRCC4–LigIV. A mutation on this surface (E326K) causes the hereditary neuro-developmental disorder, MCSZ. This mutation impairs PNKP recruitment to damaged DNA in human cells and provides a possible disease mechanism. Together, this work unveils multipoint contacts between PNKP and XRCC4–LigIV that regulate PNKP recruitment and activity within NHEJ.
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Affiliation(s)
- R Daniel Aceytuno
- Department of Biochemistry, University of Alberta, Edmonton, AB T6G-2H7, Canada
| | - Cortt G Piett
- Department of Biochemistry & Molecular Biology, Robson DNA Science Centre, Arnie Charbonneau Cancer Institute, University of Calgary, Calgary, AB T2N 1N4, Canada
| | | | - Ross A Edwards
- Department of Biochemistry, University of Alberta, Edmonton, AB T6G-2H7, Canada
| | - Martial Rey
- Department of Biochemistry & Molecular Biology, Robson DNA Science Centre, Arnie Charbonneau Cancer Institute, University of Calgary, Calgary, AB T2N 1N4, Canada
| | - Ruiqiong Ye
- Department of Biochemistry & Molecular Biology, Robson DNA Science Centre, Arnie Charbonneau Cancer Institute, University of Calgary, Calgary, AB T2N 1N4, Canada
| | - Fatima Javed
- Department of Biochemistry, University of Alberta, Edmonton, AB T6G-2H7, Canada
| | - Shujuan Fang
- Department of Biochemistry & Molecular Biology, Robson DNA Science Centre, Arnie Charbonneau Cancer Institute, University of Calgary, Calgary, AB T2N 1N4, Canada
| | - Rajam Mani
- Department of Oncology, University of Alberta, Cross Cancer Institute, 11560 University Avenue, Edmonton, Alberta T6G 1Z2, Canada
| | - Michael Weinfeld
- Department of Oncology, University of Alberta, Cross Cancer Institute, 11560 University Avenue, Edmonton, Alberta T6G 1Z2, Canada
| | - Michal Hammel
- Molecular Biophysics & Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - John A Tainer
- Molecular Biophysics & Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.,Department of Molecular and Cellular Oncology, The University of Texas M. D. Anderson Cancer Center, Houston, TX 77030, USA
| | - David C Schriemer
- Department of Biochemistry & Molecular Biology, Robson DNA Science Centre, Arnie Charbonneau Cancer Institute, University of Calgary, Calgary, AB T2N 1N4, Canada
| | - Susan P Lees-Miller
- Department of Biochemistry & Molecular Biology, Robson DNA Science Centre, Arnie Charbonneau Cancer Institute, University of Calgary, Calgary, AB T2N 1N4, Canada
| | - J N Mark Glover
- Department of Biochemistry, University of Alberta, Edmonton, AB T6G-2H7, Canada
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24
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Menon V, Povirk LF. XLF/Cernunnos: An important but puzzling participant in the nonhomologous end joining DNA repair pathway. DNA Repair (Amst) 2017; 58:29-37. [PMID: 28846869 DOI: 10.1016/j.dnarep.2017.08.003] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Revised: 07/24/2017] [Accepted: 08/07/2017] [Indexed: 01/15/2023]
Abstract
DNA double strand breaks (DSBs) are one of the most deleterious DNA lesions that promote cell death, genomic instability and carcinogenesis. The two major cellular mechanisms that repair DSBs are Nonhomologous End-Joining (NHEJ) and Homologous Recombination Repair (HRR). NHEJ is the predominant pathway, in which XLF (also called Cernunnos) is a key player. Patients with XLF mutation exhibit microcephaly, lymphopenia, and growth retardation, and are immunodeficient and radiosensitive. During NHEJ, XLF interacts with XRCC4-Ligase IV, stimulates its ligase activity, and forms DNA-binding filaments of alternating XLF and XRCC4 dimers that may serve to align broken DNA and promote ligation of noncomplementary ends. Despite its central role in NHEJ, the effects of XLF deficiency are surprisingly variable in different biological contexts, and different individual cell lines. This review summarizes the role of XLF in NHEJ, and the unexpected complexity of its interplay with other repair factors in supporting radiosurvival and V(D)J recombination.
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Affiliation(s)
- Vijay Menon
- Goodwin Research Laboratory, Massey Cancer Center, Virginia Commonwealth University, VA, USA
| | - Lawrence F Povirk
- Goodwin Research Laboratory, Massey Cancer Center, Virginia Commonwealth University, VA, USA; Department of Pharmacology and Toxicology, Virginia Commonwealth University, VA, USA.
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Fujii N. Potential Strategies to Target Protein-Protein Interactions in the DNA Damage Response and Repair Pathways. J Med Chem 2017; 60:9932-9959. [PMID: 28654754 DOI: 10.1021/acs.jmedchem.7b00358] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
This review article discusses some insights about generating novel mechanistic inhibitors of the DNA damage response and repair (DDR) pathways by focusing on protein-protein interactions (PPIs) of the key DDR components. General requirements for PPI strategies, such as selecting the target PPI site on the basis of its functionality, are discussed first. Next, on the basis of functional rationale and biochemical feasibility to identify a PPI inhibitor, 26 PPIs in DDR pathways (BER, MMR, NER, NHEJ, HR, TLS, and ICL repair) are specifically discussed for inhibitor discovery to benefit cancer therapies using a DNA-damaging agent.
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Affiliation(s)
- Naoaki Fujii
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital , 262 Danny Thomas Place, MS1000, Memphis, Tennessee 38105, United States
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26
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Normanno D, Négrel A, de Melo AJ, Betzi S, Meek K, Modesti M. Mutational phospho-mimicry reveals a regulatory role for the XRCC4 and XLF C-terminal tails in modulating DNA bridging during classical non-homologous end joining. eLife 2017; 6. [PMID: 28500754 PMCID: PMC5468090 DOI: 10.7554/elife.22900] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2016] [Accepted: 05/12/2017] [Indexed: 12/23/2022] Open
Abstract
XRCC4 and DNA Ligase 4 (LIG4) form a tight complex that provides DNA ligase activity for classical non-homologous end joining (the predominant DNA double-strand break repair pathway in higher eukaryotes) and is stimulated by XLF. Independently of LIG4, XLF also associates with XRCC4 to form filaments that bridge DNA. These XRCC4/XLF complexes rapidly load and connect broken DNA, thereby stimulating intermolecular ligation. XRCC4 and XLF both include disordered C-terminal tails that are functionally dispensable in isolation but are phosphorylated in response to DNA damage by DNA-PK and/or ATM. Here we concomitantly modify the tails of XRCC4 and XLF by substituting fourteen previously identified phosphorylation sites with either alanine or aspartate residues. These phospho-blocking and -mimicking mutations impact both the stability and DNA bridging capacity of XRCC4/XLF complexes, but without affecting their ability to stimulate LIG4 activity. Implicit in this finding is that phosphorylation may regulate DNA bridging by XRCC4/XLF filaments.
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Affiliation(s)
- Davide Normanno
- Cancer Research Center of Marseille, CNRS UMR7258, Inserm U1068, Institut Paoli-Calmettes, Aix-Marseille Université UM105, Marseille, France
| | - Aurélie Négrel
- Cancer Research Center of Marseille, CNRS UMR7258, Inserm U1068, Institut Paoli-Calmettes, Aix-Marseille Université UM105, Marseille, France
| | - Abinadabe J de Melo
- Cancer Research Center of Marseille, CNRS UMR7258, Inserm U1068, Institut Paoli-Calmettes, Aix-Marseille Université UM105, Marseille, France
| | - Stéphane Betzi
- Cancer Research Center of Marseille, CNRS UMR7258, Inserm U1068, Institut Paoli-Calmettes, Aix-Marseille Université UM105, Marseille, France
| | - Katheryn Meek
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, United States.,Department of Pathobiology and Diagnostic Investigation, College of Veterinary Medicine, Michigan State University, East Lansing, United States
| | - Mauro Modesti
- Cancer Research Center of Marseille, CNRS UMR7258, Inserm U1068, Institut Paoli-Calmettes, Aix-Marseille Université UM105, Marseille, France
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Abstract
Single-molecule FRET (smFRET) and single-molecule colocalization (smCL) assays have allowed us to observe the recombination-activating gene (RAG) complex reaction mechanism in real time. Our smFRET data have revealed distinct bending modes at recombination signal sequence (RSS)-conserved regions before nicking and synapsis. We show that high mobility group box 1 (HMGB1) acts as a cofactor in stabilizing conformational changes at the 12RSS heptamer and increasing RAG1/2 binding affinity for 23RSS. Using smCL analysis, we have quantitatively measured RAG1/2 dwell time on 12RSS, 23RSS, and non-RSS DNA, confirming a strict RSS molecular specificity that was enhanced in the presence of a partner RSS in solution. Our studies also provide single-molecule determination of rate constants that were previously only possible by indirect methods, allowing us to conclude that RAG binding, bending, and synapsis precede catalysis. Our real-time analysis offers insight into the requirements for RSS-RSS pairing, architecture of the synaptic complex, and dynamics of the paired RSS substrates. We show that the synaptic complex is extremely stable and that heptamer regions of the 12RSS and 23RSS substrates in the synaptic complex are closely associated in a stable conformational state, whereas nonamer regions are perpendicular. Our data provide an enhanced and comprehensive mechanistic description of the structural dynamics and associated enzyme kinetics of variable, diversity, and joining [V(D)J] recombination.
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28
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Sliding sleeves of XRCC4-XLF bridge DNA and connect fragments of broken DNA. Nature 2016; 535:566-9. [PMID: 27437582 DOI: 10.1038/nature18643] [Citation(s) in RCA: 113] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Accepted: 06/13/2016] [Indexed: 12/11/2022]
Abstract
Non-homologous end joining (NHEJ) is the primary pathway for repairing DNA double-strand breaks (DSBs) in mammalian cells. Such breaks are formed, for example, during gene-segment rearrangements in the adaptive immune system or by cancer therapeutic agents. Although the core components of the NHEJ machinery are known, it has remained difficult to assess the specific roles of these components and the dynamics of bringing and holding the fragments of broken DNA together. The structurally similar XRCC4 and XLF proteins are proposed to assemble as highly dynamic filaments at (or near) DSBs. Here we show, using dual- and quadruple-trap optical tweezers combined with fluorescence microscopy, how human XRCC4, XLF and XRCC4-XLF complexes interact with DNA in real time. We find that XLF stimulates the binding of XRCC4 to DNA, forming heteromeric complexes that diffuse swiftly along the DNA. Moreover, we find that XRCC4-XLF complexes robustly bridge two independent DNA molecules and that these bridges are able to slide along the DNA. These observations suggest that XRCC4-XLF complexes form mobile sleeve-like structures around DNA that can reconnect the broken ends very rapidly and hold them together. Understanding the dynamics and regulation of this mechanism will lead to clarification of how NHEJ proteins are involved in generating chromosomal translocations.
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McGovern S, Baconnais S, Roblin P, Nicolas P, Drevet P, Simonson H, Piétrement O, Charbonnier JB, Le Cam E, Noirot P, Lecointe F. C-terminal region of bacterial Ku controls DNA bridging, DNA threading and recruitment of DNA ligase D for double strand breaks repair. Nucleic Acids Res 2016; 44:4785-4806. [PMID: 26961308 PMCID: PMC4889933 DOI: 10.1093/nar/gkw149] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2015] [Revised: 02/26/2016] [Accepted: 02/29/2016] [Indexed: 01/15/2023] Open
Abstract
Non-homologous end joining is a ligation process repairing DNA double strand breaks in eukaryotes and many prokaryotes. The ring structured eukaryotic Ku binds DNA ends and recruits other factors which can access DNA ends through the threading of Ku inward the DNA, making this protein a key ingredient for the scaffolding of the NHEJ machinery. However, this threading ability seems unevenly conserved among bacterial Ku. As bacterial Ku differ mainly by their C-terminus, we evaluate the role of this region in the loading and the threading abilities of Bacillus subtilis Ku and the stimulation of the DNA ligase LigD. We identify two distinct sub-regions: a ubiquitous minimal C-terminal region and a frequent basic C-terminal extension. We show that truncation of one or both of these sub-regions in Bacillus subtilis Ku impairs the stimulation of the LigD end joining activity in vitro. We further demonstrate that the minimal C-terminus is required for the Ku-LigD interaction, whereas the basic extension controls the threading and DNA bridging abilities of Ku. We propose that the Ku basic C-terminal extension increases the concentration of Ku near DNA ends, favoring the recruitment of LigD at the break, thanks to the minimal C-terminal sub-region.
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Affiliation(s)
- Stephen McGovern
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350 Jouy-en-Josas, France
| | - Sonia Baconnais
- UMR 8126, CNRS, Gustave Roussy Université Paris Sud, Université Paris-Saclay, F-94805 Villejuif, France
| | - Pierre Roblin
- SOLEIL Synchrotron, F- 91192 Gif-sur-Yvette, INRA-URBIA, F-44316 Nantes, France
| | - Pierre Nicolas
- MaIAGE, INRA, Université Paris-Saclay, 78350 Jouy-en-Josas, France
| | - Pascal Drevet
- I2BC, iBiTec-S, CEA Saclay, UMR 9198, F-91191 Gif-sur-Yvette, France
| | - Héloïse Simonson
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350 Jouy-en-Josas, France
| | - Olivier Piétrement
- UMR 8126, CNRS, Gustave Roussy Université Paris Sud, Université Paris-Saclay, F-94805 Villejuif, France
| | | | - Eric Le Cam
- UMR 8126, CNRS, Gustave Roussy Université Paris Sud, Université Paris-Saclay, F-94805 Villejuif, France
| | - Philippe Noirot
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350 Jouy-en-Josas, France
| | - François Lecointe
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350 Jouy-en-Josas, France
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DNA double-strand-break repair in higher eukaryotes and its role in genomic instability and cancer: Cell cycle and proliferation-dependent regulation. Semin Cancer Biol 2016; 37-38:51-64. [DOI: 10.1016/j.semcancer.2016.03.003] [Citation(s) in RCA: 178] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2016] [Revised: 03/11/2016] [Accepted: 03/21/2016] [Indexed: 12/18/2022]
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31
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Bee L, Nasca A, Zanolini A, Cendron F, d'Adamo P, Costa R, Lamperti C, Celotti L, Ghezzi D, Zeviani M. A nonsense mutation of human XRCC4 is associated with adult-onset progressive encephalocardiomyopathy. EMBO Mol Med 2016; 7:918-29. [PMID: 25872942 PMCID: PMC4520657 DOI: 10.15252/emmm.201404803] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
We studied two monozygotic twins, born to first cousins, affected by a multisystem disease. At birth, they both presented with bilateral cryptorchidism and malformations. Since early adulthood, they developed a slowly progressive neurological syndrome, with cerebellar and pyramidal signs, cognitive impairment, and depression. Dilating cardiomyopathy is also present in both. By whole-exome sequencing, we found a homozygous nucleotide change in XRCC4 (c.673C>T), predicted to introduce a premature stop codon (p.R225*). XRCC4 transcript levels were profoundly reduced, and the protein was undetectable in patients' skin fibroblasts. XRCC4 plays an important role in non-homologous end joining of DNA double-strand breaks (DSB), a system that is involved in repairing DNA damage from, for example, ionizing radiations. Gamma-irradiated mutant cells demonstrated reduction, but not abolition, of DSB repair. In contrast with embryonic lethality of the Xrcc4 KO mouse, nonsense mutations in human XRCC4 have recently been associated with primordial dwarfism and, in our cases, with adult-onset neurological impairment, suggesting an important role for DNA repair in the brain. Surprisingly, neither immunodeficiency nor predisposition to malignancy was reported in these patients.
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Affiliation(s)
- Leonardo Bee
- Department of Biology, University of Padua, Padua, Italy
| | - Alessia Nasca
- Molecular Neurogenetics Unit, Foundation IRCCS Institute of Neurology "Carlo Besta", Milan, Italy
| | - Alice Zanolini
- Molecular Neurogenetics Unit, Foundation IRCCS Institute of Neurology "Carlo Besta", Milan, Italy
| | | | - Pio d'Adamo
- Department of Medical Sciences, University of Trieste, Trieste, Italy
| | - Rodolfo Costa
- Department of Biology, University of Padua, Padua, Italy
| | - Costanza Lamperti
- Molecular Neurogenetics Unit, Foundation IRCCS Institute of Neurology "Carlo Besta", Milan, Italy
| | - Lucia Celotti
- Department of Biology, University of Padua, Padua, Italy
| | - Daniele Ghezzi
- Molecular Neurogenetics Unit, Foundation IRCCS Institute of Neurology "Carlo Besta", Milan, Italy
| | - Massimo Zeviani
- Molecular Neurogenetics Unit, Foundation IRCCS Institute of Neurology "Carlo Besta", Milan, Italy MRC Mitochondrial Biology Unit, CB2 0XY, Cambridge, UK
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32
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Neal JA, Xu Y, Abe M, Hendrickson E, Meek K. Restoration of ATM Expression in DNA-PKcs-Deficient Cells Inhibits Signal End Joining. THE JOURNAL OF IMMUNOLOGY 2016; 196:3032-42. [PMID: 26921311 DOI: 10.4049/jimmunol.1501654] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Accepted: 01/26/2016] [Indexed: 11/19/2022]
Abstract
Unlike most DNA-dependent protein kinase, catalytic subunit (DNA-PKcs)-deficient mouse cell strains, we show in the present study that targeted deletion of DNA-PKcs in two different human cell lines abrogates VDJ signal end joining in episomal assays. Although the mechanism is not well defined, DNA-PKcs deficiency results in spontaneous reduction of ATM expression in many cultured cell lines (including those examined in this study) and in DNA-PKcs-deficient mice. We considered that varying loss of ATM expression might explain differences in signal end joining in different cell strains and animal models, and we investigated the impact of ATM and/or DNA-PKcs loss on VDJ recombination in cultured human and rodent cell strains. To our surprise, in DNA-PKcs-deficient mouse cell strains that are proficient in signal end joining, restoration of ATM expression markedly inhibits signal end joining. In contrast, in DNA-PKcs-deficient cells that are deficient in signal end joining, complete loss of ATM enhances signal (but not coding) joint formation. We propose that ATM facilitates restriction of signal ends to the classical nonhomologous end-joining pathway.
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Affiliation(s)
- Jessica A Neal
- Department of Microbiology and Molecular Genetics, College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824; Department of Pathobiology and Diagnostic Investigation, College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824
| | - Yao Xu
- Department of Microbiology and Molecular Genetics, College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824; Department of Pathobiology and Diagnostic Investigation, College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824
| | - Masumi Abe
- National Institute of Radiological Sciences, Chiba 263-8555, Japan; and
| | - Eric Hendrickson
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota Medical School, Minneapolis, MN 55455
| | - Katheryn Meek
- Department of Microbiology and Molecular Genetics, College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824; Department of Pathobiology and Diagnostic Investigation, College of Veterinary Medicine, Michigan State University, East Lansing, MI 48824;
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33
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Lescale C, Abramowski V, Bedora-Faure M, Murigneux V, Vera G, Roth DB, Revy P, de Villartay JP, Deriano L. RAG2 and XLF/Cernunnos interplay reveals a novel role for the RAG complex in DNA repair. Nat Commun 2016; 7:10529. [PMID: 26833222 PMCID: PMC4740868 DOI: 10.1038/ncomms10529] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2015] [Accepted: 12/22/2015] [Indexed: 12/22/2022] Open
Abstract
XRCC4-like factor (XLF) functions in classical non-homologous end-joining (cNHEJ) but is dispensable for the repair of DNA double-strand breaks (DSBs) generated during V(D)J recombination. A long-standing hypothesis proposes that, in addition to its canonical nuclease activity, the RAG1/2 proteins participate in the DNA repair phase of V(D)J recombination. Here we show that in the context of RAG2 lacking the C-terminus domain (Rag2c/c mice), XLF deficiency leads to a profound lymphopenia associated with a severe defect in V(D)J recombination and, in the absence of p53, increased genomic instability at V(D)J sites. In addition, Rag2c/cXLF−/−p53−/− mice develop aggressive pro-B cell lymphomas bearing complex chromosomal translocations and gene amplifications involving Igh and c-myc/pvt1 loci. Our results reveal an unanticipated functional interplay between the RAG complex and XLF in repairing RAG-induced DSBs and maintaining genome integrity during antigen receptor gene assembly. Antigen receptor diversity relies on careful DNA cleavage and repair. Here the authors identify a functional interplay between RAG2 and XLF during V(D)J recombination, revealing an important role for the RAG complex in repairing induced DNA double-strand breaks and maintaining genome integrity.
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Affiliation(s)
- Chloé Lescale
- Departments of Immunology and Genomes and Genetics, Institut Pasteur, CNRS-URA 1961, Paris 75015, France
| | - Vincent Abramowski
- Laboratory of Genome Dynamics in the Immune System, INSERM UMR1163, Université Paris Descartes Sorbonne Paris Cité, Institut Imagine, Paris 75015, France
| | - Marie Bedora-Faure
- Departments of Immunology and Genomes and Genetics, Institut Pasteur, CNRS-URA 1961, Paris 75015, France
| | - Valentine Murigneux
- Departments of Immunology and Genomes and Genetics, Institut Pasteur, CNRS-URA 1961, Paris 75015, France
| | - Gabriella Vera
- Laboratory of Genome Dynamics in the Immune System, INSERM UMR1163, Université Paris Descartes Sorbonne Paris Cité, Institut Imagine, Paris 75015, France
| | - David B Roth
- Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - Patrick Revy
- Laboratory of Genome Dynamics in the Immune System, INSERM UMR1163, Université Paris Descartes Sorbonne Paris Cité, Institut Imagine, Paris 75015, France
| | - Jean-Pierre de Villartay
- Laboratory of Genome Dynamics in the Immune System, INSERM UMR1163, Université Paris Descartes Sorbonne Paris Cité, Institut Imagine, Paris 75015, France
| | - Ludovic Deriano
- Departments of Immunology and Genomes and Genetics, Institut Pasteur, CNRS-URA 1961, Paris 75015, France
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Yeast DNA ligase IV mutations reveal a nonhomologous end joining function of BRCT1 distinct from XRCC4/Lif1 binding. DNA Repair (Amst) 2015; 24:37-45. [PMID: 25457772 DOI: 10.1016/j.dnarep.2014.10.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2014] [Revised: 08/23/2014] [Accepted: 10/02/2014] [Indexed: 02/03/2023]
Abstract
LIG4/Dnl4 is the DNA ligase that (re)joins DNA double-strand breaks (DSBs) via nonhomologous end joining (NHEJ), an activity supported by binding of its tandem BRCT domains to the ligase accessory protein XRCC4/Lif1. We screened a panel of 88 distinct ligase mutants to explore the structure–function relationships of the yeast Dnl4 BRCT domains and inter-BRCT linker in NHEJ. Screen results suggested two distinct classes of BRCT mutations with differential effects on Lif1 interaction as compared to NHEJ completion. Validated constructs confirmed that D800K and GG(868:869)AA mutations, which target the Lif1 binding interface, showed a severely defective Dnl4–Lif1 interaction but a less consistent and often small decrease in NHEJ activity in some assays, as well as nearly normal levels of Dnl4 accumulation at DSBs. In contrast, mutants K742A and KTT(742:744)ATA, which target the β3-α2 region of the first BRCT domain, substantially decreased NHEJ function commensurate with a large defect in Dnl4 recruitment to DSBs, despite a comparatively greater preservation of the Lif1 interaction. Together, these separation-of-function mutants indicate that Dnl4 BRCT1 supports DSB recruitment and NHEJ in a manner distinct from Lif1 binding and reveal a complexity of Dnl4 BRCT domain functions in support of stable DSB association.
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35
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Role for Artemis nuclease in the repair of radiation-induced DNA double strand breaks by alternative end joining. DNA Repair (Amst) 2015; 31:29-40. [DOI: 10.1016/j.dnarep.2015.04.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2014] [Revised: 04/14/2015] [Accepted: 04/15/2015] [Indexed: 11/24/2022]
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36
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XRCC4/XLF Interaction Is Variably Required for DNA Repair and Is Not Required for Ligase IV Stimulation. Mol Cell Biol 2015; 35:3017-28. [PMID: 26100018 DOI: 10.1128/mcb.01503-14] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Accepted: 06/15/2015] [Indexed: 01/21/2023] Open
Abstract
The classic nonhomologous end-joining (c-NHEJ) pathway is largely responsible for repairing double-strand breaks (DSBs) in mammalian cells. XLF stimulates the XRCC4/DNA ligase IV complex by an unknown mechanism. XLF interacts with XRCC4 to form filaments of alternating XRCC4 and XLF dimers that bridge DNA ends in vitro, providing a mechanism by which XLF might stimulate ligation. Here, we characterize two XLF mutants that do not interact with XRCC4 and cannot form filaments or bridge DNA in vitro. One mutant is fully sufficient in stimulating ligation by XRCC4/Lig4 in vitro; the other is not. This separation-of-function mutant (which must function as an XLF homodimer) fully complements the c-NHEJ deficits of some XLF-deficient cell strains but not others, suggesting a variable requirement for XRCC4/XLF interaction in living cells. To determine whether the lack of XRCC4/XLF interaction (and potential bridging) can be compensated for by other factors, candidate repair factors were disrupted in XLF- or XRCC4-deficient cells. The loss of either ATM or the newly described XRCC4/XLF-like factor, PAXX, accentuates the requirement for XLF. However, in the case of ATM/XLF loss (but not PAXX/XLF loss), this reflects a greater requirement for XRCC4/XLF interaction.
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37
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Heo J, Li J, Summerlin M, Hays A, Katyal S, McKinnon PJ, Nitiss KC, Nitiss JL, Hanakahi LA. TDP1 promotes assembly of non-homologous end joining protein complexes on DNA. DNA Repair (Amst) 2015; 30:28-37. [PMID: 25841101 DOI: 10.1016/j.dnarep.2015.03.003] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2014] [Revised: 02/25/2015] [Accepted: 03/09/2015] [Indexed: 11/16/2022]
Abstract
The repair of DNA double-strand breaks (DSB) is central to the maintenance of genomic integrity. In tumor cells, the ability to repair DSBs predicts response to radiation and many cytotoxic anti-cancer drugs. DSB repair pathways include homologous recombination and non-homologous end joining (NHEJ). NHEJ is a template-independent mechanism, yet many NHEJ repair products carry limited genetic changes, which suggests that NHEJ includes mechanisms to minimize error. Proteins required for mammalian NHEJ include Ku70/80, the DNA-dependent protein kinase (DNA-PKcs), XLF/Cernunnos and the XRCC4:DNA ligase IV complex. NHEJ also utilizes accessory proteins that include DNA polymerases, nucleases, and other end-processing factors. In yeast, mutations of tyrosyl-DNA phosphodiesterase (TDP1) reduced NHEJ fidelity. TDP1 plays an important role in repair of topoisomerase-mediated DNA damage and 3'-blocking DNA lesions, and mutation of the human TDP1 gene results in an inherited human neuropathy termed SCAN1. We found that human TDP1 stimulated DNA binding by XLF and physically interacted with XLF to form TDP1:XLF:DNA complexes. TDP1:XLF interactions preferentially stimulated TDP1 activity on dsDNA as compared to ssDNA. TDP1 also promoted DNA binding by Ku70/80 and stimulated DNA-PK activity. Because Ku70/80 and XLF are the first factors recruited to the DSB at the onset of NHEJ, our data suggest a role for TDP1 during the early stages of mammalian NHEJ.
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Affiliation(s)
- Jinho Heo
- Department of Medicinal Chemistry and Pharmacognosy, College of Pharmacy, University of Illinois, Chicago, Rockford Health Sciences Campus, 1601 Parkview Avenue, Rockford, IL 61107, USA
| | - Jing Li
- Department of Medicinal Chemistry and Pharmacognosy, College of Pharmacy, University of Illinois, Chicago, Rockford Health Sciences Campus, 1601 Parkview Avenue, Rockford, IL 61107, USA
| | - Matthew Summerlin
- Department of Medicinal Chemistry and Pharmacognosy, College of Pharmacy, University of Illinois, Chicago, Rockford Health Sciences Campus, 1601 Parkview Avenue, Rockford, IL 61107, USA
| | - Annette Hays
- Department of Medicinal Chemistry and Pharmacognosy, College of Pharmacy, University of Illinois, Chicago, Rockford Health Sciences Campus, 1601 Parkview Avenue, Rockford, IL 61107, USA
| | - Sachin Katyal
- University of Manitoba, Department of Pharmacology and Therapeutics, Manitoba Institute of Cell Biology, 675 McDermot Avenue, Winnipeg, Manitoba, Canada R3E 0V9
| | - Peter J McKinnon
- Department of Genetics, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA
| | - Karin C Nitiss
- Department of Biopharmaceutical Sciences, College of Pharmacy, University of Illinois, Chicago, Rockford Health Sciences Campus, 1601 Parkview Avenue, Rockford, IL 61107, USA
| | - John L Nitiss
- Department of Biopharmaceutical Sciences, College of Pharmacy, University of Illinois, Chicago, Rockford Health Sciences Campus, 1601 Parkview Avenue, Rockford, IL 61107, USA
| | - Leslyn A Hanakahi
- Department of Medicinal Chemistry and Pharmacognosy, College of Pharmacy, University of Illinois, Chicago, Rockford Health Sciences Campus, 1601 Parkview Avenue, Rockford, IL 61107, USA; Department of Biopharmaceutical Sciences, College of Pharmacy, University of Illinois, Chicago, Rockford Health Sciences Campus, 1601 Parkview Avenue, Rockford, IL 61107, USA.
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Francis DB, Kozlov M, Chavez J, Chu J, Malu S, Hanna M, Cortes P. DNA Ligase IV regulates XRCC4 nuclear localization. DNA Repair (Amst) 2014; 21:36-42. [PMID: 24984242 DOI: 10.1016/j.dnarep.2014.05.010] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2013] [Revised: 05/22/2014] [Accepted: 05/29/2014] [Indexed: 11/17/2022]
Abstract
DNA Ligase IV, along with its interacting partner XRCC4, are essential for repairing DNA double strand breaks by non-homologous end joining (NHEJ). Together, they complete the final ligation step resolving the DNA break. Ligase IV is regulated by XRCC4 and XLF. However, the mechanism(s) by which Ligase IV control the NHEJ reaction and other NHEJ factor(s) remains poorly characterized. Here, we show that a C-terminal region of Ligase IV (aa 620-800), which encompasses a NLS, the BRCT I, and the XRCC4 interacting region (XIR), is essential for nuclear localization of its co-factor XRCC4. In Ligase IV deficient cells, XRCC4 showed deregulated localization remaining in the cytosol even after induction of DNA double strand breaks. DNA Ligase IV was also required for efficient localization of XLF into the nucleus. Additionally, human fibroblasts that harbor hypomorphic mutations within the Ligase IV gene displayed decreased levels of XRCC4 protein, implicating that DNA Ligase IV is also regulating XRCC4 stability. Our results provide evidence for a role of DNA Ligase IV in controlling the cellular localization and protein levels of XRCC4.
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Affiliation(s)
- Dailia B Francis
- Immunology Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, United States; Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY 10029, United States; Graduate School of Biological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY 10029, United States
| | - Mikhail Kozlov
- Immunology Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, United States; Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY 10029, United States
| | - Jose Chavez
- Immunology Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, United States; Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY 10029, United States
| | - Jennifer Chu
- Immunology Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, United States; Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY 10029, United States
| | - Shruti Malu
- Immunology Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, United States; Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY 10029, United States
| | - Mary Hanna
- Immunology Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, United States; Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY 10029, United States
| | - Patricia Cortes
- Immunology Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, United States; Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY 10029, United States; Graduate School of Biological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY 10029, United States.
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39
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Oh S, Harvey A, Zimbric J, Wang Y, Nguyen T, Jackson PJ, Hendrickson EA. DNA ligase III and DNA ligase IV carry out genetically distinct forms of end joining in human somatic cells. DNA Repair (Amst) 2014; 21:97-110. [PMID: 24837021 DOI: 10.1016/j.dnarep.2014.04.015] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2014] [Revised: 04/15/2014] [Accepted: 04/24/2014] [Indexed: 12/11/2022]
Abstract
Ku-dependent C-NHEJ (classic non-homologous end joining) is the primary DNA EJing (end joining) repair pathway in mammals. Recently, an additional EJing repair pathway (A-NHEJ; alternative-NHEJ) has been described. Currently, the mechanism of A-NHEJ is obscure although a dependency on LIGIII (DNA ligase III) is often implicated. To test the requirement for LIGIII in A-NHEJ we constructed a LIGIII conditionally-null human cell line using gene targeting. Nuclear EJing activity appeared unaffected by a deficiency in LIGIII as, surprisingly, so were random gene targeting integration events. In contrast, LIGIII was required for mitochondrial function and this defined the gene's essential activity. Human Ku:LIGIII and Ku:LIGIV (DNA ligase IV) double knockout cell lines, however, demonstrated that LIGIII is required for the enhanced A-NHEJ activity that is observed in Ku-deficient cells. Most unexpectedly, however, the majority of EJing events remained LIGIV-dependent. In conclusion, although human LIGIII has an essential function in mitochondrial maintenance, it is dispensable for most types of nuclear DSB repair, except for the A-NHEJ events that are normally suppressed by Ku. Moreover, we describe that a robust Ku-independent, LIGIV-dependent repair pathway exists in human somatic cells.
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Affiliation(s)
- Sehyun Oh
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota Medical School, Minneapolis, MN 55455, United States.
| | - Adam Harvey
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota Medical School, Minneapolis, MN 55455, United States
| | - Jacob Zimbric
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota Medical School, Minneapolis, MN 55455, United States.
| | - Yongbao Wang
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota Medical School, Minneapolis, MN 55455, United States.
| | - Thanh Nguyen
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota Medical School, Minneapolis, MN 55455, United States
| | - Pauline J Jackson
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota Medical School, Minneapolis, MN 55455, United States
| | - Eric A Hendrickson
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota Medical School, Minneapolis, MN 55455, United States.
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40
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Ochi T, Wu Q, Blundell TL. The spatial organization of non-homologous end joining: from bridging to end joining. DNA Repair (Amst) 2014; 17:98-109. [PMID: 24636752 PMCID: PMC4037875 DOI: 10.1016/j.dnarep.2014.02.010] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2013] [Revised: 01/27/2014] [Accepted: 02/10/2014] [Indexed: 01/24/2023]
Abstract
Non-homologous end joining (NHEJ) repairs DNA double-strand breaks generated by DNA damage and also those occurring in V(D)J recombination in immunoglobulin and T cell receptor production in the immune system. In NHEJ DNA-PKcs assembles with Ku heterodimer on the DNA ends at double-strand breaks, in order to bring the broken ends together and to assemble other proteins, including DNA ligase IV (LigIV), required for DNA repair. Here we focus on structural aspects of the interactions of LigIV with XRCC4, XLF, Artemis and DNA involved in the bridging and end-joining steps of NHEJ. We begin with a discussion of the role of XLF, which interacts with Ku and forms a hetero-filament with XRCC4; this likely forms a scaffold bridging the DNA ends. We then review the well-defined interaction of XRCC4 with LigIV, and discuss the possibility of this complex interrupting the filament formation, so positioning the ligase at the correct positions close to the broken ends. We also describe the interactions of LigIV with Artemis, the nuclease that prepares the ends for ligation and also interacts with DNA-PK. Lastly we review the likely affects of Mendelian mutations on these multiprotein assemblies and their impacts on the form of inherited disease.
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Affiliation(s)
- Takashi Ochi
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge CB2 1GA, UK.
| | - Qian Wu
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge CB2 1GA, UK
| | - Tom L Blundell
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge CB2 1GA, UK
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41
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Kumar V, Alt FW, Oksenych V. Reprint of "Functional overlaps between XLF and the ATM-dependent DNA double strand break response". DNA Repair (Amst) 2014; 17:52-63. [PMID: 24767946 DOI: 10.1016/j.dnarep.2014.04.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2013] [Revised: 01/14/2014] [Accepted: 01/24/2014] [Indexed: 02/08/2023]
Abstract
Developing B and T lymphocytes generate programmed DNA double strand breaks (DSBs) during the V(D)J recombination process that assembles exons that encode the antigen-binding variable regions of antibodies. In addition, mature B lymphocytes generate programmed DSBs during the immunoglobulin heavy chain (IgH) class switch recombination (CSR) process that allows expression of different antibody heavy chain constant regions that provide different effector functions. During both V(D)J recombination and CSR, DSB intermediates are sensed by the ATM-dependent DSB response (DSBR) pathway, which also contributes to their joining via classical non-homologous end-joining (C-NHEJ). The precise nature of the interplay between the DSBR and C-NHEJ pathways in the context of DSB repair via C-NHEJ remains under investigation. Recent studies have shown that the XLF C-NHEJ factor has functional redundancy with several members of the ATM-dependent DSBR pathway in C-NHEJ, highlighting unappreciated major roles for both XLF as well as the DSBR in V(D)J recombination, CSR and C-NHEJ in general. In this review, we discuss current knowledge of the mechanisms that contribute to the repair of DSBs generated during B lymphocyte development and activation with a focus on potential functionally redundant roles of XLF and ATM-dependent DSBR factors.
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Affiliation(s)
- Vipul Kumar
- Howard Hughes Medical Institute, Program in Cellular and Molecular Medicine, Boston Children's Hospital, Department of Genetics, Harvard Medical School, Boston, MA 02115, United States
| | - Frederick W Alt
- Howard Hughes Medical Institute, Program in Cellular and Molecular Medicine, Boston Children's Hospital, Department of Genetics, Harvard Medical School, Boston, MA 02115, United States.
| | - Valentyn Oksenych
- Howard Hughes Medical Institute, Program in Cellular and Molecular Medicine, Boston Children's Hospital, Department of Genetics, Harvard Medical School, Boston, MA 02115, United States.
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42
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Ophir MJ, Liu BC, Bunnell SC. The N terminus of SKAP55 enables T cell adhesion to TCR and integrin ligands via distinct mechanisms. ACTA ACUST UNITED AC 2014; 203:1021-41. [PMID: 24368808 PMCID: PMC3871428 DOI: 10.1083/jcb.201305088] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The T cell receptor (TCR) triggers the assembly of "SLP-76 microclusters," which mediate signals required for T cell activation. In addition to regulating integrin activation, we show that Src kinase-associated phosphoprotein of 55 kD (SKAP55) is required for microcluster persistence and movement, junctional stabilization, and integrin-independent adhesion via the TCR. These functions require the dimerization of SKAP55 and its interaction with the adaptor adhesion and degranulation-promoting adaptor protein (ADAP). A "tandem dimer" containing two ADAP-binding SKAP55 Src homology 3 (SH3) domains stabilized SLP-76 microclusters and promoted T cell adhesion via the TCR, but could not support adhesion to integrin ligands. Finally, the SKAP55 dimerization motif (DM) enabled the coimmunoprecipitation of the Rap1-dependent integrin regulator Rap1-GTP-interacting adaptor molecule (RIAM), the recruitment of talin into TCR-induced adhesive junctions, and "inside-out" signaling to β1 integrins. Our data indicate that SKAP55 dimers stabilize SLP-76 microclusters, couple SLP-76 to the force-generating systems responsible for microcluster movement, and enable adhesion via the TCR by mechanisms independent of RIAM, talin, and β1 integrins.
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Affiliation(s)
- Michael J Ophir
- Program in Immunology, Sackler School of Graduate Biomedical Sciences, and 2 Department of Integrative Physiology and Pathobiology, Tufts University School of Medicine, Boston, MA 02111
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43
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Waters CA, Strande NT, Wyatt DW, Pryor JM, Ramsden DA. Nonhomologous end joining: a good solution for bad ends. DNA Repair (Amst) 2014; 17:39-51. [PMID: 24630899 DOI: 10.1016/j.dnarep.2014.02.008] [Citation(s) in RCA: 96] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2013] [Revised: 01/27/2014] [Accepted: 02/10/2014] [Indexed: 12/27/2022]
Abstract
Double strand breaks pose unique problems for DNA repair, especially when broken ends possess complex structures that interfere with standard DNA transactions. Nonhomologous end joining can use multiple strategies to solve these problems. It further uses sophisticated means to ensure the strategy chosen provides the ideal balance of flexibility and accuracy.
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Affiliation(s)
- Crystal A Waters
- Department of Biochemistry and Biophysics and Curriculum in Genetics and Molecular Biology, Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599, USA.
| | - Natasha T Strande
- Department of Biochemistry and Biophysics and Curriculum in Genetics and Molecular Biology, Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599, USA.
| | - David W Wyatt
- Department of Biochemistry and Biophysics and Curriculum in Genetics and Molecular Biology, Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599, USA.
| | - John M Pryor
- Department of Biochemistry and Biophysics and Curriculum in Genetics and Molecular Biology, Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599, USA.
| | - Dale A Ramsden
- Department of Biochemistry and Biophysics and Curriculum in Genetics and Molecular Biology, Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599, USA.
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44
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Kumar V, Alt FW, Oksenych V. Functional overlaps between XLF and the ATM-dependent DNA double strand break response. DNA Repair (Amst) 2014; 16:11-22. [PMID: 24674624 DOI: 10.1016/j.dnarep.2014.01.010] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2013] [Revised: 01/14/2014] [Accepted: 01/24/2014] [Indexed: 11/27/2022]
Abstract
Developing B and T lymphocytes generate programmed DNA double strand breaks (DSBs) during the V(D)J recombination process that assembles exons that encode the antigen-binding variable regions of antibodies. In addition, mature B lymphocytes generate programmed DSBs during the immunoglobulin heavy chain (IgH) class switch recombination (CSR) process that allows expression of different antibody heavy chain constant regions that provide different effector functions. During both V(D)J recombination and CSR, DSB intermediates are sensed by the ATM-dependent DSB response (DSBR) pathway, which also contributes to their joining via classical non-homologous end-joining (C-NHEJ). The precise nature of the interplay between the DSBR and C-NHEJ pathways in the context of DSB repair via C-NHEJ remains under investigation. Recent studies have shown that the XLF C-NHEJ factor has functional redundancy with several members of the ATM-dependent DSBR pathway in C-NHEJ, highlighting unappreciated major roles for both XLF as well as the DSBR in V(D)J recombination, CSR and C-NHEJ in general. In this review, we discuss current knowledge of the mechanisms that contribute to the repair of DSBs generated during B lymphocyte development and activation with a focus on potential functionally redundant roles of XLF and ATM-dependent DSBR factors.
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Affiliation(s)
- Vipul Kumar
- Howard Hughes Medical Institute, Program in Cellular and Molecular Medicine, Boston Children's Hospital, Department of Genetics, Harvard Medical School, Boston, MA 02115, United States
| | - Frederick W Alt
- Howard Hughes Medical Institute, Program in Cellular and Molecular Medicine, Boston Children's Hospital, Department of Genetics, Harvard Medical School, Boston, MA 02115, United States.
| | - Valentyn Oksenych
- Howard Hughes Medical Institute, Program in Cellular and Molecular Medicine, Boston Children's Hospital, Department of Genetics, Harvard Medical School, Boston, MA 02115, United States.
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45
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Fattah FJ, Kweon J, Wang Y, Lee EH, Kan Y, Lichter N, Weisensel N, Hendrickson EA. A role for XLF in DNA repair and recombination in human somatic cells. DNA Repair (Amst) 2014; 15:39-53. [PMID: 24461734 DOI: 10.1016/j.dnarep.2013.12.006] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2013] [Revised: 11/03/2013] [Accepted: 12/10/2013] [Indexed: 01/08/2023]
Abstract
Classic non-homologous end-joining (C-NHEJ) is required for the repair of radiation-induced DNA double-strand breaks (DSBs) in mammalian cells and plays a critical role in lymphoid V(D)J recombination. A core C-NHEJ component is the DNA ligase IV co-factor, Cernunnos/XLF (hereafter XLF). In patients, mutations in XLF cause predicted increases in radiosensitivity and deficits in immune function, but also cause other less well-understood pathologies including neural disorders. To characterize XLF function(s) in a defined genetic system, we used a recombinant adeno-associated virus-mediated gene targeting strategy to inactivate both copies of the XLF locus in the human HCT116 cell line. Analyses of XLF-null cells (which were viable) showed that they were highly sensitive to ionizing radiation and a radiomimetic DNA damaging agent, etoposide. XLF-null cells had profound DNA DSB repair defects as measured by in vivo plasmid end-joining assays and were also dramatically impaired in their ability to form either V(D)J coding or signal joints on extrachromosomal substrates. Thus, our somatic XLF-null cell line recapitulates many of the phenotypes expected from XLF patient cell lines. Subsequent structure:function experiments utilizing the expression of wild-type and mutant XLF cDNAs demonstrated that all of the phenotypes of an XLF deficiency could be rescued by the overexpression of a wild-type XLF cDNA. Unexpectedly, mutant forms of XLF bearing point mutations at amino acid positions L115 and L179, also completely complemented the null phenotype suggesting, in contrast to predictions to the contrary, that these mutations do not abrogate XLF function. Finally, we demonstrate that the absence of XLF causes a small, but significant, increase in homologous recombination, implicating XLF in DSB pathway choice regulation. We conclude that human XLF is a non-essential, but critical, C-NHEJ-repair factor.
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Affiliation(s)
- Farjana Jahan Fattah
- Departments of Pharmacology and Radiation Oncology, Simmons Cancer Center, University of Texas Southwestern Medical Center, Dallas, TX 75390, United States.
| | - Junghun Kweon
- Department of Pediatrics, Section of Cardiology, University of Chicago, 900 East 57th Street, KCBD Room 5240, Chicago, IL 60637, United States.
| | - Yongbao Wang
- Cancer Diagnostics Service, Quest Diagnostics Nichols Institute, Chantilly, VA 20151, United States.
| | - Eu Han Lee
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota Medical School, Minneapolis, MN 55455, United States
| | - Yinan Kan
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota Medical School, Minneapolis, MN 55455, United States
| | - Natalie Lichter
- University of ND School of Medicine, 501 Columbia Road, Grand Forks, ND 58203, United States.
| | - Natalie Weisensel
- University of Wisconsin School of Medicine and Public Health, Health Sciences Learning Center, 750 Highland Ave., Madison, WI 53705, United States.
| | - Eric A Hendrickson
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota Medical School, Minneapolis, MN 55455, United States.
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46
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Mahaney BL, Lees-Miller SP, Cobb JA. The C-terminus of Nej1 is critical for nuclear localization and non-homologous end-joining. DNA Repair (Amst) 2013; 14:9-16. [PMID: 24369855 DOI: 10.1016/j.dnarep.2013.12.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2013] [Revised: 11/14/2013] [Accepted: 12/03/2013] [Indexed: 11/25/2022]
Abstract
Nej1 is an essential factor in the non-homologous end-joining (NHEJ) pathway and interacts with the DNA ligase complex, Lif1-Dnl4, through interactions with Lif1. We have mapped K331-V338 in the C-terminal region of Nej1 to be critical for its functionality during repair. Truncation and alanine scanning mutagenesis have been used to identify a motif in Nej1, KKRK (331-334), which is important for both nuclear targeting and NHEJ repair after localization. We have identified F335-V338 to be important for proper interaction with Lif1, however this region is not required for Nej1 recruitment to HO endonuclease-induced DNA double-strand breaks in vivo. Phenylalanine at position 335 is particularly important for the role of Nej1 in repair and the loss of association between Nej1 and Lif1 correlates with a decrease in cell survival upon either transient or continuous HO expression in nej1 mutants.
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Affiliation(s)
- Brandi L Mahaney
- Department of Biochemistry and Molecular Biology, Southern Alberta Cancer Research Institute, University of Calgary, 3330 Hospital Drive NW, Calgary, AB, Canada T2N 4N1
| | - Susan P Lees-Miller
- Department of Biochemistry and Molecular Biology, Southern Alberta Cancer Research Institute, University of Calgary, 3330 Hospital Drive NW, Calgary, AB, Canada T2N 4N1
| | - Jennifer A Cobb
- Department of Biochemistry and Molecular Biology, Southern Alberta Cancer Research Institute, University of Calgary, 3330 Hospital Drive NW, Calgary, AB, Canada T2N 4N1.
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47
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Deriano L, Roth DB. Modernizing the nonhomologous end-joining repertoire: alternative and classical NHEJ share the stage. Annu Rev Genet 2013; 47:433-55. [PMID: 24050180 DOI: 10.1146/annurev-genet-110711-155540] [Citation(s) in RCA: 314] [Impact Index Per Article: 28.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
DNA double-strand breaks (DSBs) are common lesions that continually threaten genomic integrity. Failure to repair a DSB has deleterious consequences, including cell death. Misrepair is also fraught with danger, especially inappropriate end-joining events, which commonly underlie oncogenic transformation and can scramble the genome. Canonically, cells employ two basic mechanisms to repair DSBs: homologous recombination (HR) and the classical nonhomologous end-joining pathway (cNHEJ). More recent experiments identified a highly error-prone NHEJ pathway, termed alternative NHEJ (aNHEJ), which operates in both cNHEJ-proficient and cNHEJ-deficient cells. aNHEJ is now recognized to catalyze many genome rearrangements, some leading to oncogenic transformation. Here, we review the mechanisms of cNHEJ and aNHEJ, their interconnections with the DNA damage response (DDR), and the mechanisms used to determine which of the three DSB repair pathways is used to heal a particular DSB. We briefly review recent clinical applications involving NHEJ and NHEJ inhibitors.
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Affiliation(s)
- Ludovic Deriano
- Departments of Immunology and Genomes & Genetics, Institut Pasteur, CNRS-URA 1961, 75015 Paris, France;
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48
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C-terminal region of DNA ligase IV drives XRCC4/DNA ligase IV complex to chromatin. Biochem Biophys Res Commun 2013; 439:173-8. [DOI: 10.1016/j.bbrc.2013.08.068] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2013] [Accepted: 08/20/2013] [Indexed: 01/25/2023]
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49
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Vigasova D, Sarangi P, Kolesar P, Vlasáková D, Slezakova Z, Altmannova V, Nikulenkov F, Anrather D, Gith R, Zhao X, Chovanec M, Krejci L. Lif1 SUMOylation and its role in non-homologous end-joining. Nucleic Acids Res 2013; 41:5341-53. [PMID: 23571759 PMCID: PMC3664818 DOI: 10.1093/nar/gkt236] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Non-homologous end-joining (NHEJ) repairs DNA double-strand breaks by tethering and ligating the two DNA ends. The mechanisms regulating NHEJ efficiency and interplay between its components are not fully understood. Here, we identify and characterize the SUMOylation of budding yeast Lif1 protein, which is required for the ligation step in NHEJ. We show that Lif1 SUMOylation occurs throughout the cell cycle and requires the Siz SUMO ligases. Single-strand DNA, but not double-strand DNA or the Lif1 binding partner Nej1, is inhibitory to Lif1 SUMOylation. We identify lysine 301 as the major conjugation site and demonstrate that its replacement with arginine completely abolishes Lif1 SUMOylation in vivo and in vitro. The lif1-K301R mutant cells exhibit increased levels of NHEJ repair compared with wild-type cells throughout the cell cycle. This is likely due to the inhibitory effect of Lif1 SUMOylation on both its self-association and newly observed single-strand DNA binding activity. Taken together, these findings suggest that SUMOylation of Lif1 represents a new regulatory mechanism that downregulates NHEJ in a cell cycle phase-independent manner.
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Affiliation(s)
- Dana Vigasova
- Laboratory of Molecular Genetics, Cancer Research Institute, Bratislava 83391, Slovak Republic
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50
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Cottarel J, Frit P, Bombarde O, Salles B, Négrel A, Bernard S, Jeggo PA, Lieber MR, Modesti M, Calsou P. A noncatalytic function of the ligation complex during nonhomologous end joining. ACTA ACUST UNITED AC 2013; 200:173-86. [PMID: 23337116 PMCID: PMC3549972 DOI: 10.1083/jcb.201203128] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Ligase IV, but not its catalytic function, is required for DNA-PK–dependent end synapsis during nonhomologous end joining. Nonhomologous end joining is the primary deoxyribonucleic acid (DNA) double-strand break repair pathway in multicellular eukaryotes. To initiate repair, Ku binds DNA ends and recruits the DNA-dependent protein kinase (DNA-PK) catalytic subunit (DNA-PKcs) forming the holoenzyme. Early end synapsis is associated with kinase autophosphorylation. The XRCC4 (X4)–DNA Ligase IV (LIG4) complex (X4LIG4) executes the final ligation promoted by Cernunnos (Cer)–X4-like factor (XLF). In this paper, using a cell-free system that recapitulates end synapsis and DNA-PKcs autophosphorylation, we found a defect in both activities in human cell extracts lacking LIG4. LIG4 also stimulated the DNA-PKcs autophosphorylation in a reconstitution assay with purified components. We additionally uncovered a kinase autophosphorylation defect in LIG4-defective cells that was corrected by ectopic expression of catalytically dead LIG4. Finally, our data support a contribution of Cer-XLF to this unexpected early role of the ligation complex in end joining. We propose that productive end joining occurs by early formation of a supramolecular entity containing both DNA-PK and X4LIG4–Cer-XLF complexes on DNA ends.
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Affiliation(s)
- Jessica Cottarel
- Centre National de la Recherche Scientifique, Institut de Pharmacologie et de Biologie Structurale, Toulouse F-31077, Cedex 4, France
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