1
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Stinson BM, Carney SM, Walter JC, Loparo JJ. Structural role for DNA Ligase IV in promoting the fidelity of non-homologous end joining. Nat Commun 2024; 15:1250. [PMID: 38341432 PMCID: PMC10858965 DOI: 10.1038/s41467-024-45553-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Accepted: 01/25/2024] [Indexed: 02/12/2024] Open
Abstract
Nonhomologous end joining (NHEJ), the primary pathway of vertebrate DNA double-strand-break (DSB) repair, directly re-ligates broken DNA ends. Damaged DSB ends that cannot be immediately re-ligated are modified by NHEJ processing enzymes, including error-prone polymerases and nucleases, to enable ligation. However, DSB ends that are initially compatible for re-ligation are typically joined without end processing. As both ligation and end processing occur in the short-range (SR) synaptic complex that closely aligns DNA ends, it remains unclear how ligation of compatible ends is prioritized over end processing. In this study, we identify structural interactions of the NHEJ-specific DNA Ligase IV (Lig4) within the SR complex that prioritize ligation and promote NHEJ fidelity. Mutational analysis demonstrates that Lig4 must bind DNA ends to form the SR complex. Furthermore, single-molecule experiments show that a single Lig4 binds both DNA ends at the instant of SR synapsis. Thus, Lig4 is poised to ligate compatible ends upon initial formation of the SR complex before error-prone processing. Our results provide a molecular basis for the fidelity of NHEJ.
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Affiliation(s)
- Benjamin M Stinson
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA, 02115, USA
- Howard Hughes Medical Institute, Boston, MA, 02115, USA
| | - Sean M Carney
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA, 02115, USA
| | - Johannes C Walter
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA, 02115, USA.
- Howard Hughes Medical Institute, Boston, MA, 02115, USA.
| | - Joseph J Loparo
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA, 02115, USA.
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2
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Kumari N, Antil H, Kumari S, Raghavan SC. Deficiency of ligase IV leads to reduced NHEJ, accumulation of DNA damage, and can sensitize cells to cancer therapeutics. Genomics 2023; 115:110731. [PMID: 37871849 DOI: 10.1016/j.ygeno.2023.110731] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2023] [Revised: 09/14/2023] [Accepted: 10/19/2023] [Indexed: 10/25/2023]
Abstract
Ligase IV is a key enzyme involved during DNA double-strand breaks (DSBs) repair through nonhomologous end joining (NHEJ). However, in contrast to Ligase IV deficient mouse cells, which are embryonic lethal, Ligase IV deficient human cells, including pre-B cells, are viable. Using CRISPR-Cas9 mediated genome editing, we have generated six different LIG4 mutants in cervical cancer and normal kidney epithelial cell lines. While the LIG4 mutant cells showed a significant reduction in NHEJ, joining mediated through microhomology-mediated end joining (MMEJ) and homologous recombination (HR) were significantly high. The reduced NHEJ joining activity was restored by adding purified Ligase IV/XRCC4. Accumulation of DSBs and reduced cell viability were observed in LIG4 mutant cells. LIG4 mutant cells exhibited enhanced sensitivity towards DSB-inducing agents such as ionizing radiation (IR) and etoposide. More importantly, the LIG4 mutant of cervical cancer cells showed increased sensitivity towards FDA approved drugs such as Carboplatin, Cisplatin, Paclitaxel, Doxorubicin, and Bleomycin used for cervical cancer treatment. These drugs, in combination with IR showed enhanced cancer cell death in the background of LIG4 gene mutation. Thus, our study reveals that mutation in LIG4 results in compromised NHEJ, leading to sensitization of cervical cancer cells towards currently used cancer therapeutics.
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Affiliation(s)
- Nitu Kumari
- Department of Biochemistry, Indian Institute of Science, Bangalore 560012, India
| | - Himanshu Antil
- Department of Biochemistry, Indian Institute of Science, Bangalore 560012, India
| | - Susmita Kumari
- Department of Biochemistry, Indian Institute of Science, Bangalore 560012, India
| | - Sathees C Raghavan
- Department of Biochemistry, Indian Institute of Science, Bangalore 560012, India.
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3
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Vogt A, He Y. Structure and mechanism in non-homologous end joining. DNA Repair (Amst) 2023; 130:103547. [PMID: 37556875 PMCID: PMC10528545 DOI: 10.1016/j.dnarep.2023.103547] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2023] [Revised: 07/26/2023] [Accepted: 07/27/2023] [Indexed: 08/11/2023]
Abstract
DNA double-stranded breaks (DSBs) are a particularly challenging form of DNA damage to repair because the damaged DNA must not only undergo the chemical reactions responsible for returning it to its original state, but, additionally, the two free ends can become physically separated in the nucleus and must be bridged prior to repair. In nonhomologous end joining (NHEJ), one of the major pathways of DSB repair, repair is carried out by a number of repair factors capable of binding to and directly joining DNA ends. It has been unclear how these processes are carried out at a molecular level, owing in part to the lack of structural evidence describing the coordination of the NHEJ factors with each other and a DNA substrate. Advances in cryo-Electron Microscopy (cryo-EM), allowing for the structural characterization of large protein complexes that would be intractable using other techniques, have led to the visualization several key steps of the NHEJ process, which support a model of sequential assembly of repair factors at the DSB, followed by end-bridging mediated by protein-protein complexes and transition to full synapsis. Here we examine the structural evidence for these models, devoting particular attention to recent work identifying a new NHEJ intermediate state and incorporating new NHEJ factors into the general mechanism. We also discuss the evolving understanding of end-bridging mechanisms in NHEJ and DNA-PKcs's role in mediating DSB repair.
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Affiliation(s)
- Alex Vogt
- Department of Molecular Biosciences, Northwestern University, Evanston, IL, USA; Interdisciplinary Biological Sciences Program, Northwestern University, Evanston, USA
| | - Yuan He
- Department of Molecular Biosciences, Northwestern University, Evanston, IL, USA; Interdisciplinary Biological Sciences Program, Northwestern University, Evanston, USA; Chemistry of Life Processes Institute, Northwestern University, Evanston, IL, USA; Robert H. Lurie Comprehensive Cancer Center of Northwestern University, Northwestern University, Chicago, USA.
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4
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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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5
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Yin S, Liu L, Gan W. PRMT1 and PRMT5: on the road of homologous recombination and non-homologous end joining. GENOME INSTABILITY & DISEASE 2023; 4:197-209. [PMID: 37663901 PMCID: PMC10470524 DOI: 10.1007/s42764-022-00095-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2022] [Accepted: 11/28/2022] [Indexed: 09/05/2023]
Abstract
DNA double-strand breaks (DSBs) are widely accepted to be the most deleterious form of DNA lesions that pose a severe threat to genome integrity. Two predominant pathways are responsible for repair of DSBs, homologous recombination (HR) and non-homologous end-joining (NHEJ). HR relies on a template to faithfully repair breaks, while NHEJ is a template-independent and error-prone repair mechanism. Multiple layers of regulation have been documented to dictate the balance between HR and NHEJ, such as cell cycle and post-translational modifications (PTMs). Arginine methylation is one of the most common PTMs, which is catalyzed by protein arginine methyltransferases (PRMTs). PRMT1 and PRMT5 are the predominate PRMTs that promote asymmetric dimethylarginine and symmetric dimethylarginine, respectively. They have emerged to be crucial regulators of DNA damage repair. In this review, we summarize current understanding and unaddressed questions of PRMT1 and PRMT5 in regulation of HR and NHEJ, providing insights into their roles in DSB repair pathway choice and the potential of targeting them for cancer therapy.
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Affiliation(s)
- Shasha Yin
- Department of Biochemistry and Molecular Biology, Hollings Cancer Center, Medical University of South Carolina, Charleston, SC 29425, USA
| | - Liu Liu
- Department of Biochemistry and Molecular Biology, Hollings Cancer Center, Medical University of South Carolina, Charleston, SC 29425, USA
| | - Wenjian Gan
- Department of Biochemistry and Molecular Biology, Hollings Cancer Center, Medical University of South Carolina, Charleston, SC 29425, USA
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6
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Watanabe G, Lieber MR. The flexible and iterative steps within the NHEJ pathway. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2023; 180-181:105-119. [PMID: 37150451 DOI: 10.1016/j.pbiomolbio.2023.05.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 04/28/2023] [Accepted: 05/04/2023] [Indexed: 05/09/2023]
Abstract
Cellular and biochemical studies of nonhomologous DNA end joining (NHEJ) have long established that nuclease and polymerase action are necessary for the repair of a very large fraction of naturally-arising double-strand breaks (DSBs). This conclusion is derived from NHEJ studies ranging from yeast to humans and all genetically-tractable model organisms. Biochemical models derived from recent real-time and structural studies have yet to incorporate physical space or timing for DNA end processing. In real-time single molecule FRET (smFRET) studies, our lab analyzed NHEJ synapsis of DNA ends in a defined biochemical system. We described a Flexible Synapsis (FS) state in which the DNA ends were in proximity via only Ku and XRCC4:DNA ligase 4 (X4L4), and in an orientation that would not yet permit ligation until base pairing between one or more nucleotides of microhomology (MH) occurred, thereby allowing an in-line Close Synapsis (CS) state. If no MH was achievable, then XLF was critical for ligation. Neither FS or CS required DNA-PKcs, unless Artemis activation was necessary to permit local resection and subsequent base pairing between the two DNA ends being joined. Here we conjecture on possible 3D configurations for this FS state, which would spatially accommodate the nuclease and polymerase processing steps in an iterative manner. The FS model permits repeated attempts at ligation of at least one strand at the DSB after each round of nuclease or polymerase action. In addition to activation of Artemis, other possible roles for DNA-PKcs are discussed.
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Affiliation(s)
- Go Watanabe
- Departments of Pathology, Biochemistry, Molecular Microbiology & Immunology, and Section of Molecular & Computational Biology (Department of Biological Sciences), University of Southern California, Los Angeles, CA, 90089-9176, USA
| | - Michael R Lieber
- Departments of Pathology, Biochemistry, Molecular Microbiology & Immunology, and Section of Molecular & Computational Biology (Department of Biological Sciences), University of Southern California, Los Angeles, CA, 90089-9176, USA.
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7
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Ogana HA, Hurwitz S, Hsieh CL, Geng H, Müschen M, Bhojwani D, Wolf MA, Larocque J, Lieber MR, Kim YM. Artemis inhibition as a therapeutic strategy for acute lymphoblastic leukemia. Front Cell Dev Biol 2023; 11:1134121. [PMID: 37082620 PMCID: PMC10111164 DOI: 10.3389/fcell.2023.1134121] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2022] [Accepted: 03/20/2023] [Indexed: 04/03/2023] Open
Abstract
As effective therapies for relapse and refractory B-cell acute lymphoblastic leukemia (B-ALL) remain problematic, novel therapeutic strategies are needed. Artemis is a key endonuclease in V(D)J recombination and nonhomologous end joining (NHEJ) of DNA double-strand break (DSB) repair. Inhibition of Artemis would cause chromosome breaks during maturation of RAG-expressing T- and B-cells. Though this would block generation of new B- and T-cells temporarily, it could be oncologically beneficial for reducing the proliferation of B-ALL and T-ALL cells by causing chromosome breaks in these RAG-expressing tumor cells. Currently, pharmacological inhibition is not available for Artemis. According to gene expression analyses from 207 children with high-risk pre-B acute lymphoblastic leukemias high Artemis expression is correlated with poor outcome. Therefore, we evaluated four compounds (827171, 827032, 826941, and 825226), previously generated from a large Artemis targeted drug screen. A biochemical assay using a purified Artemis:DNA-PKcs complex shows that the Artemis inhibitors 827171, 827032, 826941, 825226 have nanomolar IC50 values for Artemis inhibition. We compared these 4 compounds to a DNA-PK inhibitor (AZD7648) in three patient-derived B-ALL cell lines (LAX56, BLQ5 and LAX7R) and in two mature B-cell lines (3301015 and 5680001) as controls. We found that pharmacological Artemis inhibition substantially decreases proliferation of B-ALL cell lines while normal mature B-cell lines are not markedly affected. Inhibition of DNA-PKcs (which regulates Artemis) using the DNA-PK inhibitor AZD7648 had minor effects on these same primary patient-derived ALL lines, indicating that inhibition of V(D)J hairpin opening requires direct inhibition of Artemis, rather than indirect suppression of the kinase that regulates Artemis. Our data provides a basis for further evaluation of pharmacological Artemis inhibition of proliferation of B- and T-ALL.
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Affiliation(s)
- Heather A. Ogana
- Department of Pediatrics, Children’s Hospital Los Angeles, Division of Hematology and Oncology, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States
| | - Samantha Hurwitz
- Department of Pediatrics, Children’s Hospital Los Angeles, Division of Hematology and Oncology, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States
| | - Chih-Lin Hsieh
- Department of Urology, USC Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States
| | - Huimin Geng
- Department of Laboratory Medicine, UCSF, San Francisco, CA, United States
| | - Markus Müschen
- Department of Immunobiology, Center of Molecular and Cellular Oncology, Yale University, New Haven, CT, United States
| | - Deepa Bhojwani
- Department of Pediatrics, Children’s Hospital Los Angeles, Division of Hematology and Oncology, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States
| | | | | | - Michael R. Lieber
- Departments of Pathology, The Molecular and Computational Biology Section of the Department of Biological Sciences, USC Norris Comprehensive Cancer Center, Biochemistry and Molecular Biology, Molecular Microbiology and Immunology, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States
| | - Yong Mi Kim
- Department of Pediatrics, Children’s Hospital Los Angeles, Division of Hematology and Oncology, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States
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8
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Hao Q, Zhan C, Lian C, Luo S, Cao W, Wang B, Xie X, Ye X, Gui T, Voena C, Pighi C, Wang Y, Tian Y, Wang X, Dai P, Cai Y, Liu X, Ouyang S, Sun S, Hu Q, Liu J, Ye Y, Zhao J, Lu A, Wang JY, Huang C, Su B, Meng FL, Chiarle R, Pan-Hammarström Q, Yeap LS. DNA repair mechanisms that promote insertion-deletion events during immunoglobulin gene diversification. Sci Immunol 2023; 8:eade1167. [PMID: 36961908 PMCID: PMC10351598 DOI: 10.1126/sciimmunol.ade1167] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Accepted: 03/01/2023] [Indexed: 03/26/2023]
Abstract
Insertions and deletions (indels) are low-frequency deleterious genomic DNA alterations. Despite their rarity, indels are common, and insertions leading to long complementarity-determining region 3 (CDR3) are vital for antigen-binding functions in broadly neutralizing and polyreactive antibodies targeting viruses. Because of challenges in detecting indels, the mechanism that generates indels during immunoglobulin diversification processes remains poorly understood. We carried out ultra-deep profiling of indels and systematically dissected the underlying mechanisms using passenger-immunoglobulin mouse models. We found that activation-induced cytidine deaminase-dependent ±1-base pair (bp) indels are the most prevalent indel events, biasing deleterious outcomes, whereas longer in-frame indels, especially insertions that can extend the CDR3 length, are rare outcomes. The ±1-bp indels are channeled by base excision repair, but longer indels require additional DNA-processing factors. Ectopic expression of a DNA exonuclease or perturbation of the balance of DNA polymerases can increase the frequency of longer indels, thus paving the way for models that can generate antibodies with long CDR3. Our study reveals the mechanisms that generate beneficial and deleterious indels during the process of antibody somatic hypermutation and has implications in understanding the detrimental genomic alterations in various conditions, including tumorigenesis.
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Affiliation(s)
- Qian Hao
- Center for Immune-Related Diseases at Shanghai Institute of Immunology, Department of Endocrinology and Metabolic Diseases, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
- Shanghai Institute of Immunology, Department of Immunology and Microbiology, State Key Laboratory of Oncogenes and Related Genes, Shanghai Jiao Tong University School of Medicine; 280 South Chongqing Road, Shanghai, 200025, China
| | - Chuanzong Zhan
- Center for Immune-Related Diseases at Shanghai Institute of Immunology, Department of Endocrinology and Metabolic Diseases, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
- Shanghai Institute of Immunology, Department of Immunology and Microbiology, State Key Laboratory of Oncogenes and Related Genes, Shanghai Jiao Tong University School of Medicine; 280 South Chongqing Road, Shanghai, 200025, China
| | - Chaoyang Lian
- Shanghai Institute of Immunology, Department of Immunology and Microbiology, State Key Laboratory of Oncogenes and Related Genes, Shanghai Jiao Tong University School of Medicine; 280 South Chongqing Road, Shanghai, 200025, China
| | - Simin Luo
- Shanghai Institute of Immunology, Department of Immunology and Microbiology, State Key Laboratory of Oncogenes and Related Genes, Shanghai Jiao Tong University School of Medicine; 280 South Chongqing Road, Shanghai, 200025, China
| | - Wenyi Cao
- Shanghai Institute of Immunology, Department of Immunology and Microbiology, State Key Laboratory of Oncogenes and Related Genes, Shanghai Jiao Tong University School of Medicine; 280 South Chongqing Road, Shanghai, 200025, China
| | - Binbin Wang
- Shanghai Institute of Immunology, Department of Immunology and Microbiology, State Key Laboratory of Oncogenes and Related Genes, Shanghai Jiao Tong University School of Medicine; 280 South Chongqing Road, Shanghai, 200025, China
| | - Xia Xie
- State Key Laboratory of Molecular Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences; 320 Yueyang Road, Shanghai 200031, China
| | - Xiaofei Ye
- Department of Biosciences and Nutrition, Karolinska Institutet; SE141-83, Huddinge, Stockholm, Sweden
- Present address: Kindstar Global Precision Medicine Institute, Wuhan, China and Kindstar Biotech, Wuhan, China
| | - Tuantuan Gui
- Shanghai Institute of Immunology, Department of Immunology and Microbiology, State Key Laboratory of Oncogenes and Related Genes, Shanghai Jiao Tong University School of Medicine; 280 South Chongqing Road, Shanghai, 200025, China
| | - Claudia Voena
- Department of Molecular Biotechnology and Health Sciences, University of Torino; 10126 Torino, Italy
| | - Chiara Pighi
- Department of Molecular Biotechnology and Health Sciences, University of Torino; 10126 Torino, Italy
- Department of Pathology, Boston Children’s Hospital, and Harvard Medical School; Boston, MA 02115, USA
| | - Yanyan Wang
- State Key Laboratory of Molecular Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences; 320 Yueyang Road, Shanghai 200031, China
| | - Ying Tian
- Shanghai Institute of Immunology, Department of Immunology and Microbiology, State Key Laboratory of Oncogenes and Related Genes, Shanghai Jiao Tong University School of Medicine; 280 South Chongqing Road, Shanghai, 200025, China
| | - Xin Wang
- Shanghai Institute of Immunology, Department of Immunology and Microbiology, State Key Laboratory of Oncogenes and Related Genes, Shanghai Jiao Tong University School of Medicine; 280 South Chongqing Road, Shanghai, 200025, China
| | - Pengfei Dai
- State Key Laboratory of Molecular Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences; 320 Yueyang Road, Shanghai 200031, China
| | - Yanni Cai
- State Key Laboratory of Molecular Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences; 320 Yueyang Road, Shanghai 200031, China
| | - Xiaojing Liu
- State Key Laboratory of Molecular Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences; 320 Yueyang Road, Shanghai 200031, China
| | - Shengqun Ouyang
- Center for Immune-Related Diseases at Shanghai Institute of Immunology, Department of Endocrinology and Metabolic Diseases, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
- Shanghai Institute of Immunology, Department of Immunology and Microbiology, State Key Laboratory of Oncogenes and Related Genes, Shanghai Jiao Tong University School of Medicine; 280 South Chongqing Road, Shanghai, 200025, China
| | - Shiqi Sun
- Shanghai Institute of Immunology, Department of Immunology and Microbiology, State Key Laboratory of Oncogenes and Related Genes, Shanghai Jiao Tong University School of Medicine; 280 South Chongqing Road, Shanghai, 200025, China
| | - Qianwen Hu
- Shanghai Institute of Immunology, Department of Immunology and Microbiology, State Key Laboratory of Oncogenes and Related Genes, Shanghai Jiao Tong University School of Medicine; 280 South Chongqing Road, Shanghai, 200025, China
| | - Jun Liu
- Department of Immunology, School of Basic Medical Sciences, Fudan University, Shanghai 200032, China
| | - Youqiong Ye
- Shanghai Institute of Immunology, Department of Immunology and Microbiology, State Key Laboratory of Oncogenes and Related Genes, Shanghai Jiao Tong University School of Medicine; 280 South Chongqing Road, Shanghai, 200025, China
| | - Jingkun Zhao
- Department of General Surgery, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
| | - Aiguo Lu
- Department of General Surgery, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
| | - Ji-Yang Wang
- Department of Immunology, School of Basic Medical Sciences, Fudan University, Shanghai 200032, China
- Department of Microbiology and Immunology, College of Basic Medical Sciences, Zhengzhou University, Zhengzhou, China
| | - Chuanxin Huang
- Shanghai Institute of Immunology, Department of Immunology and Microbiology, State Key Laboratory of Oncogenes and Related Genes, Shanghai Jiao Tong University School of Medicine; 280 South Chongqing Road, Shanghai, 200025, China
| | - Bing Su
- Shanghai Institute of Immunology, Department of Immunology and Microbiology, State Key Laboratory of Oncogenes and Related Genes, Shanghai Jiao Tong University School of Medicine; 280 South Chongqing Road, Shanghai, 200025, China
- Center for Immune-Related Diseases at Shanghai Institute of Immunology, Departments of Endocrinology and Gastroenterology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
- Shanghai Jiao Tong University School of Medicine-Yale Institute for Immune Metabolism, Shanghai Jiao Tong University School of Medicine, Shanghai 200025
| | - Fei-Long Meng
- State Key Laboratory of Molecular Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences; 320 Yueyang Road, Shanghai 200031, China
| | - Roberto Chiarle
- Department of Molecular Biotechnology and Health Sciences, University of Torino; 10126 Torino, Italy
- Department of Pathology, Boston Children’s Hospital, and Harvard Medical School; Boston, MA 02115, USA
| | - Qiang Pan-Hammarström
- Department of Biosciences and Nutrition, Karolinska Institutet; SE141-83, Huddinge, Stockholm, Sweden
| | - Leng-Siew Yeap
- Center for Immune-Related Diseases at Shanghai Institute of Immunology, Department of Endocrinology and Metabolic Diseases, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
- Shanghai Institute of Immunology, Department of Immunology and Microbiology, State Key Laboratory of Oncogenes and Related Genes, Shanghai Jiao Tong University School of Medicine; 280 South Chongqing Road, Shanghai, 200025, China
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9
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Mechetin GV, Zharkov DO. DNA Damage Response and Repair in Boron Neutron Capture Therapy. Genes (Basel) 2023; 14:127. [PMID: 36672868 PMCID: PMC9859301 DOI: 10.3390/genes14010127] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2022] [Revised: 12/28/2022] [Accepted: 12/29/2022] [Indexed: 01/03/2023] Open
Abstract
Boron neutron capture therapy (BNCT) is an approach to the radiotherapy of solid tumors that was first outlined in the 1930s but has attracted considerable attention recently with the advent of a new generation of neutron sources. In BNCT, tumor cells accumulate 10B atoms that react with epithermal neutrons, producing energetic α particles and 7Li atoms that damage the cell's genome. The damage inflicted by BNCT appears not to be easily repairable and is thus lethal for the cell; however, the molecular events underlying the action of BNCT remain largely unaddressed. In this review, the chemistry of DNA damage during BNCT is outlined, the major mechanisms of DNA break sensing and repair are summarized, and the specifics of the repair of BNCT-induced DNA lesions are discussed.
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Affiliation(s)
- Grigory V. Mechetin
- Department of Natural Sciences, Novosibirsk State University, 2 Pirogova St., 630090 Novosibirsk, Russia
- Siberian Branch of the Russian Academy of Sciences Institute of Chemical Biology and Fundamental Medicine, 8 Lavrentieva Ave., 630090 Novosibirsk, Russia
| | - Dmitry O. Zharkov
- Department of Natural Sciences, Novosibirsk State University, 2 Pirogova St., 630090 Novosibirsk, Russia
- Siberian Branch of the Russian Academy of Sciences Institute of Chemical Biology and Fundamental Medicine, 8 Lavrentieva Ave., 630090 Novosibirsk, Russia
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10
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A novel KU70-mutant human leukemic cell line generated using CRISPR-Cas9 shows increased sensitivity to DSB inducing agents and reduced NHEJ activity. Biochim Biophys Acta Gen Subj 2022; 1866:130246. [PMID: 36162731 DOI: 10.1016/j.bbagen.2022.130246] [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: 06/27/2022] [Revised: 09/10/2022] [Accepted: 09/19/2022] [Indexed: 11/21/2022]
Abstract
KU70 (XRCC6 gene in humans) is one of the proteins in the KU70-KU80 heterodimer which is the first component recruited to broken DNA ends during DNA double-strand break repair through nonhomologous end joining (NHEJ). Previous studies have shown that Ku70 deficient mouse cells are defective in NHEJ and V(D)J recombination. In contrast, heterozygous KU70 mutant human cell lines did not show any significant change in cell viability and sensitivity towards ionizing radiation. In this study, we used CRISPR-Cas9 technique to generate a KU70 mutant (heterozygous) human pre-B leukemic cell line (N6-KU70-2-DG). We observed that the N6-KU70-2-DG cells showed a prominent reduction in the expression of both KU70 mRNA and protein. The mutant cells showed reduced cell viability, increased sensitivity to DSB inducing agents such as ionizing radiation (IR) and etoposide, and increased number of unrepaired DSBs after exposure to IR. In addition, the mutant cells showed a reduction in the NHEJ activity and increased rate of microhomology mediated joining (MMEJ) activity. KU70 mutant cells also revealed enhanced level of senescence markers following irradiation. Thus, we report a novel KU70-mutant leukemic cell line (heterozygous) with reduced NHEJ, which is sensitive to DNA damaging agents, unlike the previously reported other KU heterozygous mutant cell lines.
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Talibova G, Bilmez Y, Ozturk S. DNA double-strand break repair in male germ cells during spermatogenesis and its association with male infertility development. DNA Repair (Amst) 2022; 118:103386. [DOI: 10.1016/j.dnarep.2022.103386] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Revised: 08/01/2022] [Accepted: 08/03/2022] [Indexed: 11/16/2022]
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12
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Sterrenberg JN, Folkerts ML, Rangel V, Lee SE, Pannunzio NR. Diversity upon diversity: linking DNA double-strand break repair to blood cancer health disparities. Trends Cancer 2022; 8:328-343. [PMID: 35094960 PMCID: PMC9248772 DOI: 10.1016/j.trecan.2022.01.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Revised: 12/20/2021] [Accepted: 01/03/2022] [Indexed: 10/19/2022]
Abstract
Chromosomal translocations arising from aberrant repair of multiple DNA double-strand breaks (DSBs) are a defining characteristic of many cancers. DSBs are an essential part of physiological processes in antibody-producing B cells. The B cell environment is poised to generate genome instability leading to translocations relevant to the pathology of blood cancers. These are a diverse set of cancers, but limited data from under-represented groups have pointed to health disparities associated with each. We focus on the DSBs that occur in developing B cells and propose the most likely mechanism behind the formation of translocations. We also highlight specific cancers in which these rearrangements occur and address the growing concern of health disparities associated with them.
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13
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Shah S, Rachmat R, Enyioma S, Ghose A, Revythis A, Boussios S. BRCA Mutations in Prostate Cancer: Assessment, Implications and Treatment Considerations. Int J Mol Sci 2021; 22:12628. [PMID: 34884434 PMCID: PMC8657599 DOI: 10.3390/ijms222312628] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Revised: 11/20/2021] [Accepted: 11/21/2021] [Indexed: 12/12/2022] Open
Abstract
Prostate cancer ranks fifth in cancer-related mortality in men worldwide. DNA damage is implicated in cancer and DNA damage response (DDR) pathways are in place against this to maintain genomic stability. Impaired DDR pathways play a role in prostate carcinogenesis and germline or somatic mutations in DDR genes have been found in both primary and metastatic prostate cancer. Among these, BRCA mutations have been found to be especially clinically relevant with a role for germline or somatic testing. Prostate cancer with DDR defects may be sensitive to poly(ADP-ribose) polymerase (PARP) inhibitors which target proteins in a process called PARylation. Initially they were used to target BRCA-mutated tumor cells in a process of synthetic lethality. However, recent studies have found potential for PARP inhibitors in a variety of other genetic settings. In this review, we explore the mechanisms of DNA repair, potential for genomic analysis of prostate cancer and therapeutics of PARP inhibitors along with their safety profile.
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Affiliation(s)
- Sidrah Shah
- Department of Palliative Care, Guy’s and St Thomas’ Hospital, Great Maze Pond, London SE1 9RT, UK;
| | - Rachelle Rachmat
- Department of Radiology, Guy’s and St Thomas’ Hospital, Great Maze Pond, London SE1 9RT, UK;
| | - Synthia Enyioma
- Department of Medical Oncology, Medway NHS Foundation Trust, Windmill Road, Gillingham ME7 5NY, UK; (S.E.); (A.R.)
| | - Aruni Ghose
- Department of Medical Oncology, Barts Cancer Centre, St. Bartholomew’s Hospital, Barts Health NHS Trust, W Smithfield, London EC1A 7BE, UK;
- Faculty of Life Sciences & Medicine, King’s College London, London WC2R 2LS, UK
| | - Antonios Revythis
- Department of Medical Oncology, Medway NHS Foundation Trust, Windmill Road, Gillingham ME7 5NY, UK; (S.E.); (A.R.)
| | - Stergios Boussios
- Department of Medical Oncology, Medway NHS Foundation Trust, Windmill Road, Gillingham ME7 5NY, UK; (S.E.); (A.R.)
- School of Cancer & Pharmaceutical Sciences, Faculty of Life Sciences & Medicine, King’s College London, London SE1 9RT, UK
- AELIA Organization, 9th Km Thessaloniki-Thermi, 57001 Thessaloniki, Greece
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Kong M, Greene EC. Mechanistic Insights From Single-Molecule Studies of Repair of Double Strand Breaks. Front Cell Dev Biol 2021; 9:745311. [PMID: 34869333 PMCID: PMC8636147 DOI: 10.3389/fcell.2021.745311] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Accepted: 10/28/2021] [Indexed: 01/01/2023] Open
Abstract
DNA double strand breaks (DSBs) are among some of the most deleterious forms of DNA damage. Left unrepaired, they are detrimental to genome stability, leading to high risk of cancer. Two major mechanisms are responsible for the repair of DSBs, homologous recombination (HR) and nonhomologous end joining (NHEJ). The complex nature of both pathways, involving a myriad of protein factors functioning in a highly coordinated manner at distinct stages of repair, lend themselves to detailed mechanistic studies using the latest single-molecule techniques. In avoiding ensemble averaging effects inherent to traditional biochemical or genetic methods, single-molecule studies have painted an increasingly detailed picture for every step of the DSB repair processes.
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Affiliation(s)
| | - Eric C. Greene
- Department of Biochemistry and Molecular Biophysics, Columbia University Irving Medical Center, New York, NY, United States
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15
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Mechanism of genome instability mediated by human DNA polymerase mu misincorporation. Nat Commun 2021; 12:3759. [PMID: 34145298 PMCID: PMC8213813 DOI: 10.1038/s41467-021-24096-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Accepted: 05/19/2021] [Indexed: 11/08/2022] Open
Abstract
Pol μ is capable of performing gap-filling repair synthesis in the nonhomologous end joining (NHEJ) pathway. Together with DNA ligase, misincorporation of dGTP opposite the templating T by Pol μ results in a promutagenic T:G mispair, leading to genomic instability. Here, crystal structures and kinetics of Pol μ substituting dGTP for dATP on gapped DNA substrates containing templating T were determined and compared. Pol μ is highly mutagenic on a 2-nt gapped DNA substrate, with T:dGTP base pairing at the 3' end of the gap. Two residues (Lys438 and Gln441) interact with T:dGTP and fine tune the active site microenvironments. The in-crystal misincorporation reaction of Pol μ revealed an unexpected second dGTP in the active site, suggesting its potential mutagenic role among human X family polymerases in NHEJ.
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Cabañas Morafraile E, Pérez-Peña J, Fuentes-Antrás J, Manzano A, Pérez-Segura P, Pandiella A, Galán-Moya EM, Ocaña A. Genomic Correlates of DNA Damage in Breast Cancer Subtypes. Cancers (Basel) 2021; 13:cancers13092117. [PMID: 33925616 PMCID: PMC8123819 DOI: 10.3390/cancers13092117] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Revised: 04/20/2021] [Accepted: 04/24/2021] [Indexed: 12/27/2022] Open
Abstract
Simple Summary Breast cancer (BC) is the most common invasive tumor in women and the second leading cause of cancer-related death. Therefore, identification of druggable targets to improve current therapies and overcome resistance is a major goal. In this work, we performed an in silico analysis of transcriptomic datasets in breast cancer, and focused on those involved in DNA damage, as were clearly upregulated using gene set enrichment analyses (GSEA), particular the following pathways: ATM/ATR, BARD1 and Fanconi Anemia. BHLHE40, RFWD2, BRIP1, PRKDC, NBN, RNF8, FANCD2, RAD1, BLM, DCLRE1C, UBE2T, CSTF1, MCM7, RFC4, YWHAB, YWHAZ, CDC6, CCNE1, and FANCI genes were amplified/overexpressed in BC, and correlated with detrimental prognosis. Finally, we selected the best transcriptomic signature of genes within this function that associated with clinical outcome to identify functional genomic correlates of outcome. Abstract Among the described druggable vulnerabilities, acting on the DNA repair mechanism has gained momentum, with the approval of PARP inhibitors in several indications, including breast cancer. However, beyond the mere presence of BRCA1/BRCA2 mutations, the identification of additional biomarkers that would help to select tumors with an extreme dependence on DNA repair machinery would help to stratify therapeutic decisions. Gene set enrichment analyses (GSEA) using public datasets evaluating expression values between normal breast tissue and breast cancer identified a set of upregulated genes. Genes included in different pathways, such as ATM/ATR, BARD1, and Fanconi Anemia, which are involved in the DNA damage response, were selected and confirmed using molecular alterations data contained at cBioportal. Nineteen genes from these gene sets were identified to be amplified and upregulated in breast cancer but only five of them NBN, PRKDC, RFWD2, UBE2T, and YWHAZ meet criteria in all breast cancer molecular subtypes. Correlation of the selected genes with prognosis (relapse free survival, RFS, and overall survival, OS) was performed using the KM Plotter Online Tool. In last place, we selected the best signature of genes within this process whose upregulation can be indicative of a more aggressive phenotype and linked with worse outcome. In summary, we identify genomic correlates within DNA damage pathway associated with prognosis in breast cancer.
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Affiliation(s)
- Esther Cabañas Morafraile
- Experimental Therapeutics Unit, Hospital Clínico San Carlos (HCSC), Instituto de Investigación Sanitaria San Carlos (IdISSC) and Centro de Investigación Biomédica en Red en Oncología (CIBERONC), 28040 Madrid, Spain; (E.C.M.); (J.F.-A.); (A.M.); (P.P.-S.)
| | - Javier Pérez-Peña
- Instituto de Biología Molecular y Celular del Cáncer del CSIC, IBSAL and CIBERONC, 37007 Salamanca, Spain; (J.P.-P.); (A.P.)
| | - Jesús Fuentes-Antrás
- Experimental Therapeutics Unit, Hospital Clínico San Carlos (HCSC), Instituto de Investigación Sanitaria San Carlos (IdISSC) and Centro de Investigación Biomédica en Red en Oncología (CIBERONC), 28040 Madrid, Spain; (E.C.M.); (J.F.-A.); (A.M.); (P.P.-S.)
| | - Aránzazu Manzano
- Experimental Therapeutics Unit, Hospital Clínico San Carlos (HCSC), Instituto de Investigación Sanitaria San Carlos (IdISSC) and Centro de Investigación Biomédica en Red en Oncología (CIBERONC), 28040 Madrid, Spain; (E.C.M.); (J.F.-A.); (A.M.); (P.P.-S.)
| | - Pedro Pérez-Segura
- Experimental Therapeutics Unit, Hospital Clínico San Carlos (HCSC), Instituto de Investigación Sanitaria San Carlos (IdISSC) and Centro de Investigación Biomédica en Red en Oncología (CIBERONC), 28040 Madrid, Spain; (E.C.M.); (J.F.-A.); (A.M.); (P.P.-S.)
| | - Atanasio Pandiella
- Instituto de Biología Molecular y Celular del Cáncer del CSIC, IBSAL and CIBERONC, 37007 Salamanca, Spain; (J.P.-P.); (A.P.)
| | - Eva M. Galán-Moya
- Translational Oncology Laboratory, Centro Regional de Investigaciones Biomédicas (CRIB) and Nursery School, Campus de Albacete, Universidad de Castilla-La Mancha, 02008 Albacete, Spain;
| | - Alberto Ocaña
- Experimental Therapeutics Unit, Hospital Clínico San Carlos (HCSC), Instituto de Investigación Sanitaria San Carlos (IdISSC) and Centro de Investigación Biomédica en Red en Oncología (CIBERONC), 28040 Madrid, Spain; (E.C.M.); (J.F.-A.); (A.M.); (P.P.-S.)
- Translational Oncology Laboratory, Centro Regional de Investigaciones Biomédicas (CRIB) and Nursery School, Campus de Albacete, Universidad de Castilla-La Mancha, 02008 Albacete, Spain;
- Correspondence:
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Ghosh D, Raghavan SC. 20 years of DNA Polymerase μ, the polymerase that still surprises. FEBS J 2021; 288:7230-7242. [DOI: 10.1111/febs.15852] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Revised: 03/02/2021] [Accepted: 03/01/2021] [Indexed: 12/22/2022]
Affiliation(s)
- Dipayan Ghosh
- Department of Biochemistry Indian Institute of Science Bangalore India
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18
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Ghosh D, Raghavan SC. Nonhomologous end joining: new accessory factors fine tune the machinery. Trends Genet 2021; 37:582-599. [PMID: 33785198 DOI: 10.1016/j.tig.2021.03.001] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Revised: 03/01/2021] [Accepted: 03/04/2021] [Indexed: 01/08/2023]
Abstract
Nonhomologous DNA end joining (NHEJ) is one of the major DNA double-strand break (DSB) repair pathways in eukaryotes. The well-known critical proteins involved in NHEJ include Ku70/80, DNA-PKcs, Artemis, DNA pol λ/μ, DNA ligase IV-XRCC4, and XLF. Recent studies have added a number of new proteins to the NHEJ repertoire namely paralog of XRCC4 and XLF (PAXX), modulator of retroviral infection (MRI)/ cell cycle regulator of NHEJ (CYREN), transactivation response DNA-binding protein (TARDBP) of 43 kDa (TDP-43), intermediate filament family orphan (IFFO1), ERCC excision repair 6 like 2 (ERCC6L2), and RNase H2. PAXX acts as a stabilizing factor for the main NHEJ components. MRI/CYREN seems to play a dual role stimulating NHEJ in the G1 phase of the cell cycle, while inhibiting the pathway in the S and G2 phases. TDP-43 can recruit the ligase IV-XRCC4 complex to the DSB sites and stimulate ligation in neuronal cells. RNase H2 excises out the ribonucleotides inserted during repair by DNA polymerase μ/TdT. This review provides a brief glimpse into how these new partners were discovered and their contribution to the mechanism and regulation of NHEJ.
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Affiliation(s)
- Dipayan Ghosh
- Department of Biochemistry, Indian Institute of Science, Bangalore 560012, India
| | - Sathees C Raghavan
- Department of Biochemistry, Indian Institute of Science, Bangalore 560012, India.
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Abbasi S, Schild-Poulter C. Identification of Ku70 Domain-Specific Interactors Using BioID2. Cells 2021; 10:cells10030646. [PMID: 33799447 PMCID: PMC8001828 DOI: 10.3390/cells10030646] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Revised: 03/04/2021] [Accepted: 03/10/2021] [Indexed: 11/23/2022] Open
Abstract
Since its inception, proximity-dependent biotin identification (BioID), an in vivo biochemical screening method to identify proximal protein interactors, has seen extensive developments. Improvements and variants of the original BioID technique are being reported regularly, each expanding upon the existing potential of the original technique. While this is advancing our capabilities to study protein interactions under different contexts, we have yet to explore the full potential of the existing BioID variants already at our disposal. Here, we used BioID2 in an innovative manner to identify and map domain-specific protein interactions for the human Ku70 protein. Four HEK293 cell lines were created, each stably expressing various BioID2-tagged Ku70 segments designed to collectively identify factors that interact with different regions of Ku70. Historically, although many interactions have been mapped to the C-terminus of the Ku70 protein, few have been mapped to the N-terminal von Willebrand A-like domain, a canonical protein-binding domain ideally situated as a site for protein interaction. Using this segmented approach, we were able to identify domain-specific interactors as well as evaluate advantages and drawbacks of the BioID2 technique. Our study identifies several potential new Ku70 interactors and validates RNF113A and Spindly as proteins that contact or co-localize with Ku in a Ku70 vWA domain-specific manner.
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20
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Liang S, Yu H. Revealing new therapeutic opportunities through drug target prediction: a class imbalance-tolerant machine learning approach. Bioinformatics 2021; 36:4490-4497. [PMID: 32399556 DOI: 10.1093/bioinformatics/btaa495] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Revised: 02/18/2020] [Accepted: 05/06/2020] [Indexed: 11/12/2022] Open
Abstract
MOTIVATION In silico drug target prediction provides valuable information for drug repurposing, understanding of side effects as well as expansion of the druggable genome. In particular, discovery of actionable drug targets is critical to developing targeted therapies for diseases. RESULTS Here, we develop a robust method for drug target prediction by leveraging a class imbalance-tolerant machine learning framework with a novel training scheme. We incorporate novel features, including drug-gene phenotype similarity and gene expression profile similarity that capture information orthogonal to other features. We show that our classifier achieves robust performance and is able to predict gene targets for new drugs as well as drugs that potentially target unexplored genes. By providing newly predicted drug-target associations, we uncover novel opportunities of drug repurposing that may benefit cancer treatment through action on either known drug targets or currently undrugged genes. SUPPLEMENTARY INFORMATION Supplementary data are available at Bioinformatics online.
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Affiliation(s)
- Siqi Liang
- Department of Computational Biology, Cornell University, Ithaca, NY 14853, USA.,Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14853, USA
| | - Haiyuan Yu
- Department of Computational Biology, Cornell University, Ithaca, NY 14853, USA.,Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14853, USA
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21
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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: 71] [Impact Index Per Article: 23.7] [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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22
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Symeonidi E, Regalado J, Schwab R, Weigel D. CRISPR-finder: A high throughput and cost-effective method to identify successfully edited Arabidopsis thaliana individuals. QUANTITATIVE PLANT BIOLOGY 2021; 2:e1. [PMID: 37077216 PMCID: PMC10095899 DOI: 10.1017/qpb.2020.6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Revised: 11/24/2020] [Accepted: 12/01/2020] [Indexed: 05/03/2023]
Abstract
Genome editing with the CRISPR/Cas (clustered regularly interspaced short palindromic repeats/CRISPR associated protein) system allows mutagenesis of a targeted region of the genome using a Cas endonuclease and an artificial guide RNA. Both because of variable efficiency with which such mutations arise and because the repair process produces a spectrum of mutations, one needs to ascertain the genome sequence at the targeted locus for many individuals that have been subjected to mutagenesis. We provide a complete protocol for the generation of amplicons up until the identification of the exact mutations in the targeted region. CRISPR-finder can be used to process thousands of individuals in a single sequencing run. We successfully identified an ISOCHORISMATE SYNTHASE 1 mutant line in which the production of salicylic acid was impaired compared to the wild type, as expected. These features establish CRISPR-finder as a high-throughput, cost-effective and efficient genotyping method of individuals whose genomes have been targeted using the CRISPR/Cas9 system.
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Affiliation(s)
- Efthymia Symeonidi
- Department of Molecular Biology, Max Planck Institute for Developmental Biology, Tübingen, Germany
| | - Julian Regalado
- Department of Molecular Biology, Max Planck Institute for Developmental Biology, Tübingen, Germany
| | - Rebecca Schwab
- Department of Molecular Biology, Max Planck Institute for Developmental Biology, Tübingen, Germany
| | - Detlef Weigel
- Department of Molecular Biology, Max Planck Institute for Developmental Biology, Tübingen, Germany
- Author for correspondence: Detlef Weigel, E-mail: Current address: Efthymia Symeonidi, Department of Biological Sciences, University of Utah, Salt Lake City, Utah84112, USA; Julian Regalado, The Globe Institute, University of Copenhagen, Øster Voldgade 5-7, 1350 Copenhagen, Denmark
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23
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The molecular basis and disease relevance of non-homologous DNA end joining. Nat Rev Mol Cell Biol 2020; 21:765-781. [PMID: 33077885 DOI: 10.1038/s41580-020-00297-8] [Citation(s) in RCA: 201] [Impact Index Per Article: 50.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/08/2020] [Indexed: 12/26/2022]
Abstract
Non-homologous DNA end joining (NHEJ) is the predominant repair mechanism of any type of DNA double-strand break (DSB) during most of the cell cycle and is essential for the development of antigen receptors. Defects in NHEJ result in sensitivity to ionizing radiation and loss of lymphocytes. The most critical step of NHEJ is synapsis, or the juxtaposition of the two DNA ends of a DSB, because all subsequent steps rely on it. Recent findings show that, like the end processing step, synapsis can be achieved through several mechanisms. In this Review, we first discuss repair pathway choice between NHEJ and other DSB repair pathways. We then integrate recent insights into the mechanisms of NHEJ synapsis with updates on other steps of NHEJ, such as DNA end processing and ligation. Finally, we discuss NHEJ-related human diseases, including inherited disorders and neoplasia, which arise from rare failures at different NHEJ steps.
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Polymerase δ promotes chromosomal rearrangements and imprecise double-strand break repair. Proc Natl Acad Sci U S A 2020; 117:27566-27577. [PMID: 33077594 DOI: 10.1073/pnas.2014176117] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Recent studies have implicated DNA polymerases θ (Pol θ) and β (Pol β) as mediators of alternative nonhomologous end-joining (Alt-NHEJ) events, including chromosomal translocations. Here we identify subunits of the replicative DNA polymerase δ (Pol δ) as promoters of Alt-NHEJ that results in more extensive intrachromosomal mutations at a single double-strand break (DSB) and more frequent translocations between two DSBs. Depletion of the Pol δ accessory subunit POLD2 destabilizes the complex, resulting in degradation of both POLD1 and POLD3 in human cells. POLD2 depletion markedly reduces the frequency of translocations with sequence modifications but does not affect the frequency of translocations with exact joins. Using separation-of-function mutants, we show that both the DNA synthesis and exonuclease activities of the POLD1 subunit contribute to translocations. As described in yeast and unlike Pol θ, Pol δ also promotes homology-directed repair. Codepletion of POLD2 with 53BP1 nearly eliminates translocations. POLD1 and POLD2 each colocalize with phosphorylated H2AX at ionizing radiation-induced DSBs but not with 53BP1. Codepletion of POLD2 with either ligase 3 (LIG3) or ligase 4 (LIG4) does not further reduce translocation frequency compared to POLD2 depletion alone. Together, these data support a model in which Pol δ promotes Alt-NHEJ in human cells at DSBs, including translocations.
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25
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Zhao B, Watanabe G, Lieber MR. Polymerase μ in non-homologous DNA end joining: importance of the order of arrival at a double-strand break in a purified system. Nucleic Acids Res 2020; 48:3605-3618. [PMID: 32052035 PMCID: PMC7144918 DOI: 10.1093/nar/gkaa094] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Revised: 01/14/2020] [Accepted: 02/04/2020] [Indexed: 01/07/2023] Open
Abstract
During non-homologous DNA end joining (NHEJ), bringing two broken dsDNA ends into proximity is an essential prerequisite for ligation by XRCC4:Ligase IV (X4L4). This physical juxtaposition of DNA ends is called NHEJ synapsis. In addition to the key NHEJ synapsis proteins, Ku, X4L4, and XLF, it has been suggested that DNA polymerase mu (pol μ) may also align two dsDNA ends into close proximity for synthesis. Here, we directly observe the NHEJ synapsis by pol μ using a single molecule FRET (smFRET) assay where we can measure the duration of the synapsis. The results show that pol μ alone can mediate efficient NHEJ synapsis of 3′ overhangs that have at least 1 nt microhomology. The abundant Ku protein in cells limits the accessibility of pol μ to DNA ends with overhangs. But X4L4 can largely reverse the Ku inhibition, perhaps by pushing the Ku inward to expose the overhang for NHEJ synapsis. Based on these studies, the mechanistic flexibility known to exist at other steps of NHEJ is now also apparent for the NHEJ synapsis step.
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Affiliation(s)
- Bailin Zhao
- Department of Pathology, Department of Biochemistry & Molecular Biology, Department of Molecular Microbiology & Immunology, and Section of Computational & Molecular Biology, USC Norris Comprehensive Cancer Center, University of Southern California Keck School of Medicine, 1441 Eastlake Ave, Rm. 5428, Los Angeles, CA 90089, USA
| | - Go Watanabe
- Department of Pathology, Department of Biochemistry & Molecular Biology, Department of Molecular Microbiology & Immunology, and Section of Computational & Molecular Biology, USC Norris Comprehensive Cancer Center, University of Southern California Keck School of Medicine, 1441 Eastlake Ave, Rm. 5428, Los Angeles, CA 90089, USA
| | - Michael R Lieber
- Department of Pathology, Department of Biochemistry & Molecular Biology, Department of Molecular Microbiology & Immunology, and Section of Computational & Molecular Biology, USC Norris Comprehensive Cancer Center, University of Southern California Keck School of Medicine, 1441 Eastlake Ave, Rm. 5428, Los Angeles, CA 90089, USA
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26
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Ubiquitylation-Mediated Fine-Tuning of DNA Double-Strand Break Repair. Cancers (Basel) 2020; 12:cancers12061617. [PMID: 32570875 PMCID: PMC7352447 DOI: 10.3390/cancers12061617] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Revised: 06/15/2020] [Accepted: 06/17/2020] [Indexed: 01/04/2023] Open
Abstract
The proper function of DNA repair is indispensable for eukaryotic cells since accumulation of DNA damages leads to genome instability and is a major cause of oncogenesis. Ubiquitylation and deubiquitylation play a pivotal role in the precise regulation of DNA repair pathways by coordinating the recruitment and removal of repair proteins at the damaged site. Here, we summarize the most important post-translational modifications (PTMs) involved in DNA double-strand break repair. Although we highlight the most relevant PTMs, we focus principally on ubiquitylation-related processes since these are the most robust regulatory pathways among those of DNA repair.
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27
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Zhu X, Cong J, Lin Z, Sun J, Yang B, Li A. Inhibition of HMGB1 Overcomes Resistance to Radiation and Chemotherapy in Nasopharyngeal Carcinoma. Onco Targets Ther 2020; 13:4189-4199. [PMID: 32523355 PMCID: PMC7236242 DOI: 10.2147/ott.s239243] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Accepted: 03/25/2020] [Indexed: 01/25/2023] Open
Abstract
Objective This study aimed to investigate the effect of high mobility group protein B1 (HMGB1) on chemoresistance and radioresistance in nasopharyngeal carcinoma (NPC). Materials and Methods HMGB1-knockout HK1 cell lines were generated using clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9 (CRISPR/Cas9) system. Western blotting was used to evaluate the protein expression level of HMGB1. DNA repair efficiency of non-homologous end joining (NHEJ) and homologous recombination (HR) was monitored through NHEJ and HR reporter assay. Cellular protein–protein interaction between HMGB1 and NHEJ apparatus was determined by immunoprecipitation. Direct protein–protein interaction was examined by affinity capture assay with purified protein. Protein-DNA binding was evaluated by chromatin fractionation assay. Cell viability assay was employed to measure cell sensitivity to ionizing radiation (IR) or cisplatin. Results HMGB1-knockout NPC cells showed significant decrease in NHEJ efficiency. HMGB1 immunoprecipitated NHEJ key factors in NPC cells and promoted DNA-binding activity of Ku70. Mutational analysis revealed that serine 155 of Ku70 was required for its direct interaction with HMGB1. HMGB1 was highly expressed in radio- and chemoresistant NPC cells. Deficiency of HMGB1 sensitized wild-type (WT) and resistant NPC cells to IR and cisplatin. Glycyrrhizin, which is HMGB1 inhibitor, impaired DNA binding of HMGB1 and exhibited excellent synergy with IR and cisplatin. Conclusion HMGB1 promotes NHEJ via interaction with Ku70 resulting in resistance to IR and cisplatin. Inhibition of HMGB1 by glycyrrhizin is a potential therapeutic regimen to treat cisplatin and IR resistant NPC patients.
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Affiliation(s)
- Xuewei Zhu
- Department of Otolaryngology Head and Neck Surgery, China-Japan Union Hospital of Jilin University, Changchun, Jilin, People's Republic of China
| | - Jianan Cong
- Department of Ophthalmology, Changchun City Central Hospital, Changchun, Jilin, People's Republic of China
| | - Zhang Lin
- Department of Ophthalmology, China-Japan Union Hospital of Jilin University, Changchun, Jilin, People's Republic of China
| | - Jing Sun
- Department of Biochemistry and Molecular Biology, The George Washington University, Washington, DC, USA
| | - Ben Yang
- Department of Ophthalmology, China-Japan Union Hospital of Jilin University, Changchun, Jilin, People's Republic of China
| | - Aipeng Li
- Department of Ophthalmology, The First Hospital of Jilin University, Changchun, Jilin, People's Republic of China
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28
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MiRNAs Targeting Double Strand DNA Repair Pathways Lurk in Genomically Unstable Rare Fragile Sites and Determine Cancer Outcomes. Cancers (Basel) 2020; 12:cancers12040876. [PMID: 32260317 PMCID: PMC7226545 DOI: 10.3390/cancers12040876] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Revised: 03/31/2020] [Accepted: 04/02/2020] [Indexed: 12/12/2022] Open
Abstract
Double strand break (DSB) repair mechanisms guard genome integrity and their deterioration causes genomic instability. Common and rare fragile sites (CFS and RFS, respectively) are particularly vulnerable to instability, and there is an inverse correlation between fragile site (FS) expression and DSB repair protein levels. Upon DSB repair dysfunction, genes residing at these sites are at greater risk of deregulation compared to genes located at non-FS. In this regard, it remains enigmatic why the incidence of miRNA genes at FS is higher compared to non-FS. Herein, using bioinformatics, we examined whether miRNA genes localized at FS inhibit components of DSB repair pathways and assessed their effects on cancer. We show that such miRNAs over-accumulate in RFS, and that FRAXA, which is expressed in Fragile X syndrome, is a conserved hotspot for miRNAs inhibiting DSB repair. Axes of FRAXA-residing miRNAs/DSB repair targets affect survival in a cancer type-specific manner. Moreover, copy number variations in the region encompassing these miRNA genes discriminate survival between male and female patients. Given that, thus far, only CFS have been considered relevant for carcinogenesis, our data are the first to associate RFS with cancer, through the impairment of DSB repair by the FRAXA-residing miRNAs.
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29
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Serrano-Benítez A, Cortés-Ledesma F, Ruiz JF. "An End to a Means": How DNA-End Structure Shapes the Double-Strand Break Repair Process. Front Mol Biosci 2020; 6:153. [PMID: 31998749 PMCID: PMC6965357 DOI: 10.3389/fmolb.2019.00153] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Accepted: 12/11/2019] [Indexed: 12/12/2022] Open
Abstract
Endogenously-arising DNA double-strand breaks (DSBs) rarely harbor canonical 5′-phosphate, 3′-hydroxyl moieties at the ends, which are, regardless of the pathway used, ultimately required for their repair. Cells are therefore endowed with a wide variety of enzymes that can deal with these chemical and structural variations and guarantee the formation of ligatable termini. An important distinction is whether the ends are directly “unblocked” by specific enzymatic activities without affecting the integrity of the DNA molecule and its sequence, or whether they are “processed” by unspecific nucleases that remove nucleotides from the termini. DNA end structure and configuration, therefore, shape the repair process, its requirements, and, importantly, its final outcome. Thus, the molecular mechanisms that coordinate and integrate the cellular response to blocked DSBs, although still largely unexplored, can be particularly relevant for maintaining genome integrity and avoiding malignant transformation and cancer.
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Affiliation(s)
- Almudena Serrano-Benítez
- Andalusian Center of Molecular Biology and Regenerative Medicine (CABIMER-CSIC-University of Seville-Pablo de Olavide University), Seville, Spain
| | - Felipe Cortés-Ledesma
- Andalusian Center of Molecular Biology and Regenerative Medicine (CABIMER-CSIC-University of Seville-Pablo de Olavide University), Seville, Spain.,Topology and DNA breaks Group, Spanish National Cancer Research Center, Madrid, Spain
| | - Jose F Ruiz
- Andalusian Center of Molecular Biology and Regenerative Medicine (CABIMER-CSIC-University of Seville-Pablo de Olavide University), Seville, Spain.,Department of Plant Biochemistry and Molecular Biology, University of Seville, Seville, Spain
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30
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Pharmacological methods to transcriptionally modulate double-strand break DNA repair. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2019; 354:187-213. [PMID: 32475473 DOI: 10.1016/bs.ircmb.2019.11.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
There is much interest in targeting DNA repair pathways for use in cancer therapy, as the effectiveness of many therapeutic agents relies on their ability to cause damage to DNA, and deficiencies in DSB repair pathways can make cells more sensitive to specific cancer therapies. For example, defects in the double-strand break (DSB) pathways, non-homologous end joining (NHEJ) and homology-directed repair (HDR), induce sensitivity to radiation therapy and poly(ADP)-ribose polymerase (PARP) inhibitors, respectively. However, traditional approaches to inhibit DNA repair through small molecule inhibitors have often been limited by toxicity and poor bioavailability. This review identifies several pharmacologic manipulations that modulate DSB repair by reducing expression of DNA repair factors. A number of pathways have been identified that modulate activity of NHEJ and HDR through this mechanism, including growth and hormonal receptor signaling pathways as well as epigenetic modifiers. We also discuss the effects of anti-angiogenic therapy on DSB repair. Preclinically, these pharmacological manipulations of DNA repair factor expression have been shown to increase sensitivity to specific cancer therapies, including ionizing radiation and PARP inhibitors. When applicable, relevant clinical trials are discussed and areas for future study are identified.
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31
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Stinson BM, Moreno AT, Walter JC, Loparo JJ. A Mechanism to Minimize Errors during Non-homologous End Joining. Mol Cell 2019; 77:1080-1091.e8. [PMID: 31862156 DOI: 10.1016/j.molcel.2019.11.018] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Revised: 10/09/2019] [Accepted: 11/22/2019] [Indexed: 01/15/2023]
Abstract
Enzymatic processing of DNA underlies all DNA repair, yet inappropriate DNA processing must be avoided. In vertebrates, double-strand breaks are repaired predominantly by non-homologous end joining (NHEJ), which directly ligates DNA ends. NHEJ has the potential to be highly mutagenic because it uses DNA polymerases, nucleases, and other enzymes that modify incompatible DNA ends to allow their ligation. Using frog egg extracts that recapitulate NHEJ, we show that end processing requires the formation of a "short-range synaptic complex" in which DNA ends are closely aligned in a ligation-competent state. Furthermore, single-molecule imaging directly demonstrates that processing occurs within the short-range complex. This confinement of end processing to a ligation-competent complex ensures that DNA ends undergo ligation as soon as they become compatible, thereby minimizing mutagenesis. Our results illustrate how the coordination of enzymatic catalysis with higher-order structural organization of substrate maximizes the fidelity of DNA repair.
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Affiliation(s)
- Benjamin M Stinson
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
| | - Andrew T Moreno
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA
| | - Johannes C Walter
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA; Howard Hughes Medical Institute, Boston, MA 02115, USA.
| | - Joseph J Loparo
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA.
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32
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Trimidal SG, Benjamin R, Bae JE, Han MV, Kong E, Singer A, Williams TS, Yang B, Schiller MR. Can Designer Indels Be Tailored by Gene Editing?: Can Indels Be Customized? Bioessays 2019; 41:e1900126. [PMID: 31693213 DOI: 10.1002/bies.201900126] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Revised: 10/01/2019] [Indexed: 12/23/2022]
Abstract
Genome editing with engineered nucleases (GEENs) introduce site-specific DNA double-strand breaks (DSBs) and repairs DSBs via nonhomologous end-joining (NHEJ) pathways that eventually create indels (insertions/deletions) in a genome. Whether the features of indels resulting from gene editing could be customized is asked. A review of the literature reveals how gene editing technologies via NHEJ pathways impact gene editing. The survey consolidates a body of literature that suggests that the type (insertion, deletion, and complex) and the approximate length of indel edits can be somewhat customized with different GEENs and by manipulating the expression of key NHEJ genes. Structural data suggest that binding of GEENs to DNA may interfere with binding of key components of DNA repair complexes, favoring either classical- or alternative-NHEJ. The hypotheses have some limitations, but if validated, will enable scientists to better control indel makeup, holding promise for basic science and clinical applications of gene editing. Also see the video abstract here https://youtu.be/vTkJtUsLi3w.
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Affiliation(s)
- Sara G Trimidal
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, NV, 89154, USA.,Nevada Institute of Personalized Medicine, University of Nevada Las Vegas, Las Vegas, NV, 89154, USA
| | - Ronald Benjamin
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, NV, 89154, USA.,Nevada Institute of Personalized Medicine, University of Nevada Las Vegas, Las Vegas, NV, 89154, USA
| | - Ji Eun Bae
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, NV, 89154, USA.,Nevada Institute of Personalized Medicine, University of Nevada Las Vegas, Las Vegas, NV, 89154, USA
| | - Mira V Han
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, NV, 89154, USA.,Nevada Institute of Personalized Medicine, University of Nevada Las Vegas, Las Vegas, NV, 89154, USA
| | - Elizabeth Kong
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, NV, 89154, USA.,Nevada Institute of Personalized Medicine, University of Nevada Las Vegas, Las Vegas, NV, 89154, USA
| | - Aaron Singer
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, NV, 89154, USA.,Nevada Institute of Personalized Medicine, University of Nevada Las Vegas, Las Vegas, NV, 89154, USA
| | - Tyler S Williams
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, NV, 89154, USA.,Nevada Institute of Personalized Medicine, University of Nevada Las Vegas, Las Vegas, NV, 89154, USA
| | - Bing Yang
- Donald Danforth Plant Science Center, St. Louis, MO, 63132, USA
| | - Martin R Schiller
- School of Life Sciences, University of Nevada Las Vegas, Las Vegas, NV, 89154, USA.,Nevada Institute of Personalized Medicine, University of Nevada Las Vegas, Las Vegas, NV, 89154, USA
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33
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Ray S, Breuer G, DeVeaux M, Zelterman D, Bindra R, Sweasy JB. DNA polymerase beta participates in DNA End-joining. Nucleic Acids Res 2019; 46:242-255. [PMID: 29161447 PMCID: PMC5758893 DOI: 10.1093/nar/gkx1147] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Accepted: 10/31/2017] [Indexed: 12/21/2022] Open
Abstract
DNA double strand breaks (DSBs) are one of the most deleterious lesions and if left unrepaired, they lead to cell death, genomic instability and carcinogenesis. Cells combat DSBs by two pathways: homologous recombination (HR) and non-homologous end-joining (NHEJ), wherein the two DNA ends are re-joined. Recently a back-up NHEJ pathway has been reported and is referred to as alternative NHEJ (aNHEJ), which joins ends but results in deletions and insertions. NHEJ requires processing enzymes including nucleases and polymerases, although the roles of these enzymes are poorly understood. Emerging evidence indicates that X family DNA polymerases lambda (Pol λ) and mu (Pol μ) promote DNA end-joining. Here, we show that DNA polymerase beta (Pol β), another member of the X family of DNA polymerases, plays a role in aNHEJ. In the absence of DNA Pol β, fewer small deletions are observed. In addition, depletion of Pol β results in cellular sensitivity to bleomycin and DNA protein kinase catalytic subunit inhibitors due to defective repair of DSBs. In summary, our results indicate that Pol β in functions in aNHEJ and provide mechanistic insight into its role in this process.
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Affiliation(s)
- Sreerupa Ray
- Department of Therapeutic Radiology, School of Public Health, Yale University School of Medicine, New Haven, CT 06520-8034, USA
| | - Gregory Breuer
- Department of Therapeutic Radiology, School of Public Health, Yale University School of Medicine, New Haven, CT 06520-8034, USA.,Department of Pathology, School of Public Health, Yale University School of Medicine, New Haven, CT 06520-8034, USA
| | - Michelle DeVeaux
- School of Public Health, Yale University School of Medicine, New Haven, CT 06520-8034, USA
| | - Daniel Zelterman
- School of Public Health, Yale University School of Medicine, New Haven, CT 06520-8034, USA
| | - Ranjit Bindra
- Department of Therapeutic Radiology, School of Public Health, Yale University School of Medicine, New Haven, CT 06520-8034, USA.,Department of Pathology, School of Public Health, Yale University School of Medicine, New Haven, CT 06520-8034, USA
| | - Joann B Sweasy
- Department of Therapeutic Radiology, School of Public Health, Yale University School of Medicine, New Haven, CT 06520-8034, USA.,Department of Genetics, School of Public Health, Yale University School of Medicine, New Haven, CT 06520-8034, USA
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34
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Toma M, Skorski T, Sliwinski T. DNA Double Strand Break Repair - Related Synthetic Lethality. Curr Med Chem 2019; 26:1446-1482. [PMID: 29421999 DOI: 10.2174/0929867325666180201114306] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Revised: 11/10/2017] [Accepted: 11/16/2017] [Indexed: 12/25/2022]
Abstract
Cancer is a heterogeneous disease with a high degree of diversity between and within tumors. Our limited knowledge of their biology results in ineffective treatment. However, personalized approach may represent a milestone in the field of anticancer therapy. It can increase specificity of treatment against tumor initiating cancer stem cells (CSCs) and cancer progenitor cells (CPCs) with minimal effect on normal cells and tissues. Cancerous cells carry multiple genetic and epigenetic aberrations which may disrupt pathways essential for cell survival. Discovery of synthetic lethality has led a new hope of creating effective and personalized antitumor treatment. Synthetic lethality occurs when simultaneous inactivation of two genes or their products causes cell death whereas individual inactivation of either gene is not lethal. The effectiveness of numerous anti-tumor therapies depends on induction of DNA damage therefore tumor cells expressing abnormalities in genes whose products are crucial for DNA repair pathways are promising targets for synthetic lethality. Here, we discuss mechanistic aspects of synthetic lethality in the context of deficiencies in DNA double strand break repair pathways. In addition, we review clinical trials utilizing synthetic lethality interactions and discuss the mechanisms of resistance.
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Affiliation(s)
- Monika Toma
- Laboratory of Medical Genetics, Faculty of Biology and Environmental Protection, University of Lodz, Pomorska 141/143, 90-236 Lodz, Poland
| | - Tomasz Skorski
- Department of Microbiology and Immunology, 3400 North Broad Street, Temple University Lewis Katz School of Medicine, Philadelphia, PA 19140, United States
| | - Tomasz Sliwinski
- Laboratory of Medical Genetics, Faculty of Biology and Environmental Protection, University of Lodz, Pomorska 141/143, 90-236 Lodz, Poland
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35
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Radiosensitizing activity of novel small molecule BRCA1 and DNA-PK inhibitors in lung and colon carcinoma. JOURNAL OF RADIATION RESEARCH AND APPLIED SCIENCES 2019. [DOI: 10.1016/j.jrras.2017.04.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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36
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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: 50] [Impact Index Per Article: 10.0] [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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37
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Thapar U, Demple B. Deployment of DNA polymerases beta and lambda in single-nucleotide and multinucleotide pathways of mammalian base excision DNA repair. DNA Repair (Amst) 2019; 76:11-19. [PMID: 30763888 DOI: 10.1016/j.dnarep.2019.02.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2018] [Revised: 01/08/2019] [Accepted: 02/01/2019] [Indexed: 11/17/2022]
Abstract
There exist two major base excision DNA repair (BER) pathways, namely single-nucleotide or "short-patch" (SP-BER), and "long-patch" BER (LP-BER). Both pathways appear to be involved in the repair of small base lesions such as uracil, abasic sites and oxidized bases. In addition to DNA polymerase β (Polβ) as the main BER enzyme for repair synthesis, there is evidence for a minor role for DNA polymerase lambda (Polλ) in BER. In this study we explore the potential contribution of Polλ to both SP- and LP-BER in cell-free extracts. We measured BER activity in extracts of mouse embryonic fibroblasts using substrates with either a single uracil or the chemically stable abasic site analog tetrahydrofuran residue. The addition of purified Polλ complemented the pronounced BER deficiency of POLB-null cell extracts as efficiently as did Polβ itself. We have developed a new approach for determining the relative contributions of SP- and LP-BER pathways, exploiting mass-labeled nucleotides to distinguish single- and multinucleotide repair patches. Using this method, we found that uracil repair in wild-type and in Polβ-deficient cell extracts supplemented with Polλ was ∼80% SP-BER. The results show that recombinant Polλ can contribute to both SP- and LP-BER. However, endogenous Polλ, which is present at a level ˜50% that of Polβ in mouse embryonic fibroblasts, appears to make little contribution to BER in extracts. Thus Polλ in cells appears to be under some constraint, perhaps sequestered in a complex with other proteins, or post-translationally modified in a way that limits its ability to participate effectively in BER.
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Affiliation(s)
- Upasna Thapar
- Molecular and Cellular Biology Program, Stony Brook University, Stony Brook, NY 11794, United States; Department of Pharmacological Sciences, Stony Brook University School of Medicine, Stony Brook, NY, 11794, United States
| | - Bruce Demple
- Molecular and Cellular Biology Program, Stony Brook University, Stony Brook, NY 11794, United States; Department of Pharmacological Sciences, Stony Brook University School of Medicine, Stony Brook, NY, 11794, United States.
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38
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PAXX and its paralogs synergistically direct DNA polymerase λ activity in DNA repair. Nat Commun 2018; 9:3877. [PMID: 30250067 PMCID: PMC6155126 DOI: 10.1038/s41467-018-06127-y] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Accepted: 08/09/2018] [Indexed: 12/20/2022] Open
Abstract
PAXX is a recently identified component of the nonhomologous end joining (NHEJ) DNA repair pathway. The molecular mechanisms of PAXX action remain largely unclear. Here we characterise the interactomes of PAXX and its paralogs, XLF and XRCC4, to show that these factors share the ability to interact with DNA polymerase λ (Pol λ), stimulate its activity and are required for recruitment of Pol λ to laser-induced DNA damage sites. Stimulation of Pol λ activity by XRCC4 paralogs requires a direct interaction between the SP/8 kDa domain of Pol λ and their N-terminal head domains to facilitate recognition of the 5′ end of substrate gaps. Furthermore, PAXX and XLF collaborate with Pol λ to promote joining of incompatible DNA ends and are redundant in supporting Pol λ function in vivo. Our findings identify Pol λ as a novel downstream effector of PAXX function and show XRCC4 paralogs act in synergy to regulate polymerase activity in NHEJ. PAXX functions as part of the nonhomologous end-joining pathway to repair double-strand DNA breaks. Here the authors show PAXX and its paralogs interact with polymerase lambda to promote joining of incompatible ends.
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39
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Archer TC, Ehrenberger T, Mundt F, Gold MP, Krug K, Mah CK, Mahoney EL, Daniel CJ, LeNail A, Ramamoorthy D, Mertins P, Mani DR, Zhang H, Gillette MA, Clauser K, Noble M, Tang LC, Pierre-François J, Silterra J, Jensen J, Tamayo P, Korshunov A, Pfister SM, Kool M, Northcott PA, Sears RC, Lipton JO, Carr SA, Mesirov JP, Pomeroy SL, Fraenkel E. Proteomics, Post-translational Modifications, and Integrative Analyses Reveal Molecular Heterogeneity within Medulloblastoma Subgroups. Cancer Cell 2018; 34:396-410.e8. [PMID: 30205044 PMCID: PMC6372116 DOI: 10.1016/j.ccell.2018.08.004] [Citation(s) in RCA: 118] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Revised: 06/28/2018] [Accepted: 08/03/2018] [Indexed: 12/18/2022]
Abstract
There is a pressing need to identify therapeutic targets in tumors with low mutation rates such as the malignant pediatric brain tumor medulloblastoma. To address this challenge, we quantitatively profiled global proteomes and phospho-proteomes of 45 medulloblastoma samples. Integrated analyses revealed that tumors with similar RNA expression vary extensively at the post-transcriptional and post-translational levels. We identified distinct pathways associated with two subsets of SHH tumors, and found post-translational modifications of MYC that are associated with poor outcomes in group 3 tumors. We found kinases associated with subtypes and showed that inhibiting PRKDC sensitizes MYC-driven cells to radiation. Our study shows that proteomics enables a more comprehensive, functional readout, providing a foundation for future therapeutic strategies.
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Affiliation(s)
- Tenley C Archer
- Department of Neurology, Boston Children's Hospital, Boston, MA, USA; Harvard Medical School, Boston, MA, USA; Division of Sleep Medicine, Harvard Medical School, Boston, MA, USA; Eli and Edythe Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Tobias Ehrenberger
- Department of Biological Engineering, Massachusetts Institute of Technology (MIT), Cambridge, MA, USA
| | - Filip Mundt
- Eli and Edythe Broad Institute of MIT and Harvard, Cambridge, MA, USA; Department of Oncology-Pathology, Karolinska Institute, Stockholm, Sweden
| | - Maxwell P Gold
- Department of Biological Engineering, Massachusetts Institute of Technology (MIT), Cambridge, MA, USA
| | - Karsten Krug
- Eli and Edythe Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Clarence K Mah
- Department of Medicine, University of California San Diego (UCSD), La Jolla, CA, USA
| | - Elizabeth L Mahoney
- Department of Neurology, Boston Children's Hospital, Boston, MA, USA; Harvard Medical School, Boston, MA, USA
| | - Colin J Daniel
- Department of Molecular and Medical Genetics, Oregon Health and Science University (OHSU), Portland, OR, USA
| | - Alexander LeNail
- Department of Biological Engineering, Massachusetts Institute of Technology (MIT), Cambridge, MA, USA
| | - Divya Ramamoorthy
- Department of Biological Engineering, Massachusetts Institute of Technology (MIT), Cambridge, MA, USA
| | - Philipp Mertins
- Eli and Edythe Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - D R Mani
- Eli and Edythe Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Hailei Zhang
- Eli and Edythe Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Michael A Gillette
- Harvard Medical School, Boston, MA, USA; Eli and Edythe Broad Institute of MIT and Harvard, Cambridge, MA, USA; Division of Pulmonary and Critical Care Medicine, Massachusetts General Hospital (MGH), Boston, MA, USA
| | - Karl Clauser
- Eli and Edythe Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Michael Noble
- Eli and Edythe Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Lauren C Tang
- Eli and Edythe Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Jessica Pierre-François
- Department of Neurology, Boston Children's Hospital, Boston, MA, USA; Harvard Medical School, Boston, MA, USA
| | - Jacob Silterra
- Eli and Edythe Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - James Jensen
- Department of Medicine, University of California San Diego (UCSD), La Jolla, CA, USA
| | - Pablo Tamayo
- Department of Medicine, University of California San Diego (UCSD), La Jolla, CA, USA; Moores Cancer Center, University of California San Diego (UCSD), La Jolla, CA, USA
| | - Andrey Korshunov
- CCU Neuropathology, German Cancer Research Center (DKFZ), Heidelberg, Germany; Department of Neuropathology, Heidelberg University, Heidelberg, Germany
| | - Stefan M Pfister
- Hopp Children's Cancer Center at the NCT Heidelberg (KiTZ), Heidelberg, Germany; Division of Pediatric Neurooncology, German Cancer Research Center (DKFZ) and German Cancer Consortium (DKTK), Heidelberg, Germany; Department of Hematology and Oncology, Heidelberg University Hospital, Heidelberg, Germany
| | - Marcel Kool
- Hopp Children's Cancer Center at the NCT Heidelberg (KiTZ), Heidelberg, Germany; Division of Pediatric Neurooncology, German Cancer Research Center (DKFZ) and German Cancer Consortium (DKTK), Heidelberg, Germany
| | - Paul A Northcott
- Division of Pediatric Neurooncology, German Cancer Research Center (DKFZ) and German Cancer Consortium (DKTK), Heidelberg, Germany; Department of Developmental Neurobiology, St Jude Children's Research Hospital, Memphis, TN, USA
| | - Rosalie C Sears
- Department of Molecular and Medical Genetics, Oregon Health and Science University (OHSU), Portland, OR, USA
| | - Jonathan O Lipton
- Department of Neurology, Boston Children's Hospital, Boston, MA, USA; Harvard Medical School, Boston, MA, USA; Division of Sleep Medicine, Harvard Medical School, Boston, MA, USA
| | - Steven A Carr
- Eli and Edythe Broad Institute of MIT and Harvard, Cambridge, MA, USA.
| | - Jill P Mesirov
- Department of Medicine, University of California San Diego (UCSD), La Jolla, CA, USA; Moores Cancer Center, University of California San Diego (UCSD), La Jolla, CA, USA.
| | - Scott L Pomeroy
- Department of Neurology, Boston Children's Hospital, Boston, MA, USA; Harvard Medical School, Boston, MA, USA; Eli and Edythe Broad Institute of MIT and Harvard, Cambridge, MA, USA.
| | - Ernest Fraenkel
- Eli and Edythe Broad Institute of MIT and Harvard, Cambridge, MA, USA; Department of Biological Engineering, Massachusetts Institute of Technology (MIT), Cambridge, MA, USA.
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40
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Kirby TW, Pedersen LC, Gabel SA, Gassman NR, London RE. Variations in nuclear localization strategies among pol X family enzymes. Traffic 2018; 19:10.1111/tra.12600. [PMID: 29931796 PMCID: PMC6684861 DOI: 10.1111/tra.12600] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2017] [Revised: 06/19/2018] [Accepted: 06/20/2018] [Indexed: 12/22/2022]
Abstract
Despite the essential roles of pol X family enzymes in DNA repair, information about the structural basis of their nuclear import is limited. Recent studies revealed the unexpected presence of a functional nuclear localization signal (NLS) in DNA polymerase β, indicating the importance of active nuclear targeting, even for enzymes likely to leak into and out of the nucleus. The current studies further explore the active nuclear transport of these enzymes by identifying and structurally characterizing the functional NLS sequences in the three remaining human pol X enzymes: terminal deoxynucleotidyl transferase (TdT), DNA polymerase mu (pol μ) and DNA polymerase lambda (pol λ). NLS identifications are based on Importin α (Impα) binding affinity determined by fluorescence polarization of fluorescein-labeled NLS peptides, X-ray crystallographic analysis of the Impα∆IBB•NLS complexes and fluorescence-based subcellular localization studies. All three polymerases use NLS sequences located near their N-terminus; TdT and pol μ utilize monopartite NLS sequences, while pol λ utilizes a bipartite sequence, unique among the pol X family members. The pol μ NLS has relatively weak measured affinity for Impα, due in part to its proximity to the N-terminus that limits non-specific interactions of flanking residues preceding the NLS. However, this effect is partially mitigated by an N-terminal sequence unsupportive of Met1 removal by methionine aminopeptidase, leading to a 3-fold increase in affinity when the N-terminal methionine is present. Nuclear targeting is unique to each pol X family enzyme with variations dependent on the structure and unique functional role of each polymerase.
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Affiliation(s)
- Thomas W Kirby
- National Institute of Environmental Health Sciences, Genome Integrity and Structural Biology Laboratory, National Institutes of Health, Research Triangle Park, North Carolina
| | - Lars C Pedersen
- National Institute of Environmental Health Sciences, Genome Integrity and Structural Biology Laboratory, National Institutes of Health, Research Triangle Park, North Carolina
| | - Scott A Gabel
- National Institute of Environmental Health Sciences, Genome Integrity and Structural Biology Laboratory, National Institutes of Health, Research Triangle Park, North Carolina
| | - Natalie R Gassman
- Molecular & Metabolic Oncology, University of South Alabama Mitchell Cancer Institute, Mobile, Alabama
| | - Robert E London
- National Institute of Environmental Health Sciences, Genome Integrity and Structural Biology Laboratory, National Institutes of Health, Research Triangle Park, North Carolina
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41
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Loc'h J, Delarue M. Terminal deoxynucleotidyltransferase: the story of an untemplated DNA polymerase capable of DNA bridging and templated synthesis across strands. Curr Opin Struct Biol 2018; 53:22-31. [PMID: 29656238 DOI: 10.1016/j.sbi.2018.03.019] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Revised: 03/27/2018] [Accepted: 03/30/2018] [Indexed: 01/08/2023]
Abstract
Terminal deoxynucleotidyltransferase (TdT) is a member of the polX family which is involved in DNA repair. It has been known for years as an untemplated DNA polymerase used during V(D)J recombination to generate diversity at the CDR3 region of immunoglobulins and T-cell receptors. Recently, however, TdT was crystallized in the presence of a complete DNA synapsis made of two double-stranded DNA (dsDNA), each with a 3' protruding end, and overlapping with only one micro-homology base-pair, thus giving structural insight for the first time into DNA synthesis across strands. It was subsequently shown that TdT indeed has an in trans template-dependent activity in the presence of an excess of the downstream DNA duplex. A possible biological role of this dual activity is discussed.
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Affiliation(s)
- Jérôme Loc'h
- Unit of Structural Dynamics of Biological Macromolecules and UMR 3528 du CNRS, Institut Pasteur, 75015 Paris, France
| | - Marc Delarue
- Unit of Structural Dynamics of Biological Macromolecules and UMR 3528 du CNRS, Institut Pasteur, 75015 Paris, France.
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42
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Helena JM, Joubert AM, Grobbelaar S, Nolte EM, Nel M, Pepper MS, Coetzee M, Mercier AE. Deoxyribonucleic Acid Damage and Repair: Capitalizing on Our Understanding of the Mechanisms of Maintaining Genomic Integrity for Therapeutic Purposes. Int J Mol Sci 2018; 19:E1148. [PMID: 29641431 PMCID: PMC5979424 DOI: 10.3390/ijms19041148] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Revised: 03/19/2018] [Accepted: 03/23/2018] [Indexed: 12/31/2022] Open
Abstract
Deoxyribonucleic acid (DNA) is the self-replicating hereditary material that provides a blueprint which, in collaboration with environmental influences, produces a structural and functional phenotype. As DNA coordinates and directs differentiation, growth, survival, and reproduction, it is responsible for life and the continuation of our species. Genome integrity requires the maintenance of DNA stability for the correct preservation of genetic information. This is facilitated by accurate DNA replication and precise DNA repair. DNA damage may arise from a wide range of both endogenous and exogenous sources but may be repaired through highly specific mechanisms. The most common mechanisms include mismatch, base excision, nucleotide excision, and double-strand DNA (dsDNA) break repair. Concurrent with regulation of the cell cycle, these mechanisms are precisely executed to ensure full restoration of damaged DNA. Failure or inaccuracy in DNA repair contributes to genome instability and loss of genetic information which may lead to mutations resulting in disease or loss of life. A detailed understanding of the mechanisms of DNA damage and its repair provides insight into disease pathogeneses and may facilitate diagnosis and the development of targeted therapies.
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Affiliation(s)
- Jolene Michelle Helena
- Department of Physiology, School of Medicine, Faculty of Health Sciences, University of Pretoria, Pretoria 0002, South Africa.
| | - Anna Margaretha Joubert
- Department of Physiology, School of Medicine, Faculty of Health Sciences, University of Pretoria, Pretoria 0002, South Africa.
| | - Simone Grobbelaar
- Department of Physiology, School of Medicine, Faculty of Health Sciences, University of Pretoria, Pretoria 0002, South Africa.
| | - Elsie Magdalena Nolte
- Department of Physiology, School of Medicine, Faculty of Health Sciences, University of Pretoria, Pretoria 0002, South Africa.
| | - Marcel Nel
- Department of Physiology, School of Medicine, Faculty of Health Sciences, University of Pretoria, Pretoria 0002, South Africa.
| | - Michael Sean Pepper
- Institute for Cellular and Molecular Medicine, Department of Immunology, South African Medical Research Council (SAMRC) Extramural Unit for Stem Cell Research and Therapy, Faculty of Health Sciences, University of Pretoria, Pretoria 0002, South Africa.
| | - Magdalena Coetzee
- Department of Physiology, School of Medicine, Faculty of Health Sciences, University of Pretoria, Pretoria 0002, South Africa.
| | - Anne Elisabeth Mercier
- Department of Physiology, School of Medicine, Faculty of Health Sciences, University of Pretoria, Pretoria 0002, South Africa.
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43
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Pannunzio NR, Watanabe G, Lieber MR. Nonhomologous DNA end-joining for repair of DNA double-strand breaks. J Biol Chem 2017; 293:10512-10523. [PMID: 29247009 DOI: 10.1074/jbc.tm117.000374] [Citation(s) in RCA: 314] [Impact Index Per Article: 44.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Nonhomologous DNA end-joining (NHEJ) is the predominant double-strand break (DSB) repair pathway throughout the cell cycle and accounts for nearly all DSB repair outside of the S and G2 phases. NHEJ relies on Ku to thread onto DNA termini and thereby improve the affinity of the NHEJ enzymatic components consisting of polymerases (Pol μ and Pol λ), a nuclease (the Artemis·DNA-PKcs complex), and a ligase (XLF·XRCC4·Lig4 complex). Each of the enzymatic components is distinctive for its versatility in acting on diverse incompatible DNA end configurations coupled with a flexibility in loading order, resulting in many possible junctional outcomes from one DSB. DNA ends can either be directly ligated or, if the ends are incompatible, processed until a ligatable configuration is achieved that is often stabilized by up to 4 bp of terminal microhomology. Processing of DNA ends results in nucleotide loss or addition, explaining why DSBs repaired by NHEJ are rarely restored to their original DNA sequence. Thus, NHEJ is a single pathway with multiple enzymes at its disposal to repair DSBs, resulting in a diversity of repair outcomes.
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Affiliation(s)
- Nicholas R Pannunzio
- From the Departments of Pathology, Biochemistry and Molecular Biology, and Molecular Microbiology and Immunology, Section of Molecular and Computational Biology, Department of Biological Sciences, Norris Comprehensive Cancer Center, University of Southern California Keck School of Medicine, Los Angeles, California 90033
| | - Go Watanabe
- From the Departments of Pathology, Biochemistry and Molecular Biology, and Molecular Microbiology and Immunology, Section of Molecular and Computational Biology, Department of Biological Sciences, Norris Comprehensive Cancer Center, University of Southern California Keck School of Medicine, Los Angeles, California 90033
| | - Michael R Lieber
- From the Departments of Pathology, Biochemistry and Molecular Biology, and Molecular Microbiology and Immunology, Section of Molecular and Computational Biology, Department of Biological Sciences, Norris Comprehensive Cancer Center, University of Southern California Keck School of Medicine, Los Angeles, California 90033
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44
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Weeden CE, Asselin-Labat ML. Mechanisms of DNA damage repair in adult stem cells and implications for cancer formation. Biochim Biophys Acta Mol Basis Dis 2017; 1864:89-101. [PMID: 29038050 DOI: 10.1016/j.bbadis.2017.10.015] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Revised: 10/06/2017] [Accepted: 10/11/2017] [Indexed: 02/06/2023]
Abstract
Maintenance of genomic integrity in tissue-specific stem cells is critical for tissue homeostasis and the prevention of deleterious diseases such as cancer. Stem cells are subject to DNA damage induced by endogenous replication mishaps or exposure to exogenous agents. The type of DNA lesion and the cell cycle stage will invoke different DNA repair mechanisms depending on the intrinsic DNA repair machinery of a cell. Inappropriate DNA repair in stem cells can lead to cell death, or to the formation and accumulation of genetic alterations that can be transmitted to daughter cells and so is linked to cancer formation. DNA mutational signatures that are associated with DNA repair deficiencies or exposure to carcinogenic agents have been described in cancer. Here we review the most recent findings on DNA repair pathways activated in epithelial tissue stem and progenitor cells and their implications for cancer mutational signatures. We discuss how deep knowledge of early molecular events leading to carcinogenesis provides insights into DNA repair mechanisms operating in tumours and how these could be exploited therapeutically.
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Affiliation(s)
- Clare E Weeden
- ACRF Stem Cells and Cancer Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia; Department of Medical Biology, The University of Melbourne, Parkville, Victoria, Australia
| | - Marie-Liesse Asselin-Labat
- ACRF Stem Cells and Cancer Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia; Department of Medical Biology, The University of Melbourne, Parkville, Victoria, Australia.
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45
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Reid DA, Conlin MP, Yin Y, Chang HH, Watanabe G, Lieber MR, Ramsden DA, Rothenberg E. Bridging of double-stranded breaks by the nonhomologous end-joining ligation complex is modulated by DNA end chemistry. Nucleic Acids Res 2017; 45:1872-1878. [PMID: 27924007 PMCID: PMC5389564 DOI: 10.1093/nar/gkw1221] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2016] [Accepted: 11/22/2016] [Indexed: 01/02/2023] Open
Abstract
The nonhomologous end-joining (NHEJ) pathway is the primary repair pathway for DNA double strand breaks (DSBs) in humans. Repair is mediated by a core complex of NHEJ factors that includes a ligase (DNA Ligase IV; L4) that relies on juxtaposition of 3΄ hydroxyl and 5΄ phosphate termini of the strand breaks for catalysis. However, chromosome breaks arising from biological sources often have different end chemistries, and how these different end chemistries impact the way in which the core complex directs the necessary transitions from end pairing to ligation is not known. Here, using single-molecule FRET (smFRET), we show that prior to ligation, differences in end chemistry strongly modulate the bridging of broken ends by the NHEJ core complex. In particular, the 5΄ phosphate group is a recognition element for L4 and is critical for the ability of NHEJ factors to promote stable pairing of ends. Moreover, other chemical incompatibilities, including products of aborted ligation, are sufficient to disrupt end pairing. Based on these observations, we propose a mechanism for iterative repair of DSBs by NHEJ.
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Affiliation(s)
- Dylan A Reid
- New York University School of Medicine, Department of Biochemistry and Molecular Pharmacology, New York, NY 10016, USA
| | - Michael P Conlin
- University of North Carolina School of Medicine, Curriculum in Genetics and Molecular Biology and Department of Biochemistry and Biophysics, Chapel Hill, NC 27599, USA
| | - Yandong Yin
- New York University School of Medicine, Department of Biochemistry and Molecular Pharmacology, New York, NY 10016, USA
| | - Howard H Chang
- University of Southern California Keck School of Medicine, Norris Comprehensive Cancer Center, Los Angeles, CA 90033, USA
| | - Go Watanabe
- University of Southern California Keck School of Medicine, Norris Comprehensive Cancer Center, Los Angeles, CA 90033, USA
| | - Michael R Lieber
- University of Southern California Keck School of Medicine, Norris Comprehensive Cancer Center, Los Angeles, CA 90033, USA
| | - Dale A Ramsden
- University of North Carolina School of Medicine, Curriculum in Genetics and Molecular Biology and Department of Biochemistry and Biophysics, Chapel Hill, NC 27599, USA
| | - Eli Rothenberg
- New York University School of Medicine, Department of Biochemistry and Molecular Pharmacology, New York, NY 10016, USA
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46
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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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47
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Sastre-Moreno G, Pryor JM, Díaz-Talavera A, Ruiz JF, Ramsden DA, Blanco L. Polμ tumor variants decrease the efficiency and accuracy of NHEJ. Nucleic Acids Res 2017; 45:10018-10031. [PMID: 28973441 PMCID: PMC5622330 DOI: 10.1093/nar/gkx625] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Revised: 07/03/2017] [Accepted: 07/12/2017] [Indexed: 11/14/2022] Open
Abstract
The non homologous end-joining (NHEJ) pathway of double-strand break (DSB) repair often requires DNA synthesis to fill the gaps generated upon alignment of the broken ends, a complex task performed in human cells by two specialized DNA polymerases, Polλ and Polμ. It is now well established that Polμ is the one adapted to repair DSBs with non-complementary ends, the most challenging scenario, although the structural basis and physiological implications of this adaptation are not fully understood. Here, we demonstrate that two human Polμ point mutations, G174S and R175H, previously identified in two different tumor samples and affecting two adjacent residues, limit the efficiency of accurate NHEJ by Polμ in vitro and in vivo. Moreover, we show that this limitation is the consequence of a decreased template dependency during NHEJ, which renders the error-rate of the mutants higher due to the ability of Polμ to randomly incorporate nucleotides at DSBs. These results highlight the relevance of the 8 kDa domain of Polμ for accurate and efficient NHEJ, but also its contribution to the error-prone behavior of Polμ at 2-nt gaps. This work provides the first demonstration that mutations affecting Polμ identified in tumors can alter the efficiency and fidelity of NHEJ.
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Affiliation(s)
- Guillermo Sastre-Moreno
- Centro de Biología Molecular ‘Severo Ochoa’, Universidad Autónoma de Madrid/CSIC, Madrid, Spain
| | - 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
| | - Alberto Díaz-Talavera
- Centro de Biología Molecular ‘Severo Ochoa’, Universidad Autónoma de Madrid/CSIC, Madrid, Spain
| | - José F. Ruiz
- Departamento Bioquímica Vegetal y Biología Molecular, Universidad de Sevilla, Sevilla, Spain
- Centro Andaluz de Biología Molecular y Medicina Regenerativa (CABIMER), Universidad de Sevilla/CSIC, Sevilla, Spain
| | - 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
| | - Luis Blanco
- Centro de Biología Molecular ‘Severo Ochoa’, Universidad Autónoma de Madrid/CSIC, Madrid, Spain
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48
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Seol JH, Shim EY, Lee SE. Microhomology-mediated end joining: Good, bad and ugly. Mutat Res 2017; 809:81-87. [PMID: 28754468 DOI: 10.1016/j.mrfmmm.2017.07.002] [Citation(s) in RCA: 149] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Revised: 06/21/2017] [Accepted: 07/03/2017] [Indexed: 01/06/2023]
Abstract
DNA double-strand breaks (DSBs) are induced by a variety of genotoxic agents, including ionizing radiation and chemotherapy drugs for treating cancers. The elimination of DSBs proceeds via distinctive error-free and error-prone pathways. Repair by homologous recombination (HR) is largely error-free and mediated by RAD51/BRCA2 gene products. Classical non-homologous end joining (C-NHEJ) requires the Ku heterodimer and can efficiently rejoin breaks, with occasional loss or gain of DNA information. Recently, evidence has unveiled another DNA end-joining mechanism that is independent of recombination factors and Ku proteins, termed alternative non-homologous end joining (A-NHEJ). While A-NHEJ-mediated repair does not require homology, in a subtype of A-NHEJ, DSB breaks are sealed by microhomology (MH)-mediated base-pairing of DNA single strands, followed by nucleolytic trimming of DNA flaps, DNA gap filling, and DNA ligation, yielding products that are always associated with DNA deletion. This highly error-prone DSB repair pathway is termed microhomology-mediated end joining (MMEJ). Dissecting the mechanisms of MMEJ is of great interest because of its potential to destabilize the genome through gene deletions and chromosomal rearrangements in cells deficient in canonical repair pathways, including HR and C-NHEJ. In addition, evidence now suggests that MMEJ plays a physiological role in normal cells.
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Affiliation(s)
- Ja-Hwan Seol
- Department of Molecular Medicine, Institute of Biotechnology, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229-3900, United States
| | - Eun Yong Shim
- Department of Radiation Oncology, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229-3900, United States
| | - Sang Eun Lee
- Department of Molecular Medicine, Institute of Biotechnology, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229-3900, United States; Department of Radiation Oncology, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229-3900, United States.
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49
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Gerodimos CA, Chang HHY, Watanabe G, Lieber MR. Effects of DNA end configuration on XRCC4-DNA ligase IV and its stimulation of Artemis activity. J Biol Chem 2017; 292:13914-13924. [PMID: 28696258 DOI: 10.1074/jbc.m117.798850] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Revised: 07/05/2017] [Indexed: 11/06/2022] Open
Abstract
In humans, nonhomologous DNA end-joining (NHEJ) is the major pathway by which DNA double-strand breaks are repaired. Recognition of each broken DNA end by the DNA repair protein Ku is the first step in NHEJ, followed by the iterative binding of nucleases, DNA polymerases, and the XRCC4-DNA ligase IV (X4-LIV) complex in an order influenced by the configuration of the two DNA ends at the break site. The endonuclease Artemis improves joining efficiency by functioning in a complex with DNA-dependent protein kinase, catalytic subunit (DNA-PKcs) that carries out endonucleolytic cleavage of 5' and 3' overhangs. Previously, we observed that X4-LIV alone can stimulate Artemis activity on 3' overhangs, but this DNA-PKcs-independent endonuclease activity of Artemis awaited confirmation. Here, using in vitro nuclease and ligation assays, we find that stimulation of Artemis nuclease activity by X4-LIV and the efficiency of blunt-end ligation are determined by structural configurations at the DNA end. Specifically, X4-LIV stimulated Artemis to cut near the end of 3' overhangs without the involvement of other NHEJ proteins. Of note, this ligase complex is not able to stimulate Artemis activity at hairpins or at 5' overhangs. We also found that X4-LIV and DNA-PKcs interfere with one another with respect to stimulating Artemis activity at 3' overhangs, favoring the view that these NHEJ proteins are sequentially rather than concurrently recruited to DNA ends. These data suggest specific functional and positional relationships among these components that explain genetic and molecular features of NHEJ and V(D)J recombination within cells.
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Affiliation(s)
- Christina A Gerodimos
- From the Departments of Pathology, Biochemistry & Molecular Biology, and Molecular Microbiology & Immunology and the Department of Biological Sciences, Section of Molecular & Computational Biology, Norris Comprehensive Cancer Center, University of Southern California Keck School of Medicine, Los Angeles, California 90033
| | - Howard H Y Chang
- From the Departments of Pathology, Biochemistry & Molecular Biology, and Molecular Microbiology & Immunology and the Department of Biological Sciences, Section of Molecular & Computational Biology, Norris Comprehensive Cancer Center, University of Southern California Keck School of Medicine, Los Angeles, California 90033
| | - Go Watanabe
- From the Departments of Pathology, Biochemistry & Molecular Biology, and Molecular Microbiology & Immunology and the Department of Biological Sciences, Section of Molecular & Computational Biology, Norris Comprehensive Cancer Center, University of Southern California Keck School of Medicine, Los Angeles, California 90033
| | - Michael R Lieber
- From the Departments of Pathology, Biochemistry & Molecular Biology, and Molecular Microbiology & Immunology and the Department of Biological Sciences, Section of Molecular & Computational Biology, Norris Comprehensive Cancer Center, University of Southern California Keck School of Medicine, Los Angeles, California 90033.
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Non-homologous DNA end joining and alternative pathways to double-strand break repair. Nat Rev Mol Cell Biol 2017; 18:495-506. [PMID: 28512351 DOI: 10.1038/nrm.2017.48] [Citation(s) in RCA: 975] [Impact Index Per Article: 139.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
DNA double-strand breaks (DSBs) are the most dangerous type of DNA damage because they can result in the loss of large chromosomal regions. In all mammalian cells, DSBs that occur throughout the cell cycle are repaired predominantly by the non-homologous DNA end joining (NHEJ) pathway. Defects in NHEJ result in sensitivity to ionizing radiation and the ablation of lymphocytes. The NHEJ pathway utilizes proteins that recognize, resect, polymerize and ligate the DNA ends in a flexible manner. This flexibility permits NHEJ to function on a wide range of DNA-end configurations, with the resulting repaired DNA junctions often containing mutations. In this Review, we discuss the most recent findings regarding the relative involvement of the different NHEJ proteins in the repair of various DNA-end configurations. We also discuss the shunting of DNA-end repair to the auxiliary pathways of alternative end joining (a-EJ) or single-strand annealing (SSA) and the relevance of these different pathways to human disease.
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