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He J, Kou SH, Li J, Ding X, Wang SM. Pathogenic variants in human DNA damage repair genes mostly arose after the latest human out-of-Africa migration. Front Genet 2024; 15:1408952. [PMID: 38948361 PMCID: PMC11211533 DOI: 10.3389/fgene.2024.1408952] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2024] [Accepted: 05/21/2024] [Indexed: 07/02/2024] Open
Abstract
Introduction The DNA damage repair (DDR) system in human genome is pivotal in maintaining genomic integrity. Pathogenic variation (PV) in DDR genes impairs their function, leading to genome instability and increased susceptibility to diseases, especially cancer. Understanding the evolution origin and arising time of DDR PV is crucial for comprehending disease susceptibility in modern humans. Methods We used big data approach to identify the PVs in DDR genes in modern humans. We mined multiple genomic databases derived from 251,214 modern humans of African and non-Africans. We compared the DDR PVs between African and non-African. We also mined the DDR PVs in the genomic data derived from 5,031 ancient humans. We used the DDR PVs from ancient humans as the intermediate to further the DDR PVs between African and non-African. Results and discussion We identified 1,060 single-base DDR PVs across 77 DDR genes in modern humans of African and non-African. Direct comparison of the DDR PVs between African and non-African showed that 82.1% of the non-African PVs were not present in African. We further identified 397 single-base DDR PVs in 56 DDR genes in the 5,031 ancient humans dated between 45,045 and 100 years before present (BP) lived in Eurasian continent therefore the descendants of the latest out-of-Africa human migrants occurred 50,000-60,000 years ago. By referring to the ancient DDR PVs, we observed that 276 of the 397 (70.3%) ancient DDR PVs were exclusive in non-African, 106 (26.7%) were shared between non-African and African, and only 15 (3.8%) were exclusive in African. We further validated the distribution pattern by testing the PVs in BRCA and TP53, two of the important genes in genome stability maintenance, in African, non-African, and Ancient humans. Our study revealed that DDR PVs in modern humans mostly emerged after the latest out-of-Africa migration. The data provides a foundation to understand the evolutionary basis of disease susceptibility, in particular cancer, in modern humans.
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Affiliation(s)
| | | | | | | | - San Ming Wang
- Department of Public Health and Medical Administration, Faculty of Health Sciences, Ministry of Education Frontiers Science Center for Precision Oncology, Cancer Centre and Institute of Translational Medicine, University of Macau, Taipa, China
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2
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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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3
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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 PMCID: PMC10205690 DOI: 10.1016/j.pbiomolbio.2023.05.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [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, we 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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4
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Kowalska A, Nasonova E, Kutsalo P, Czerski K. Chromosomal radiosensitivity of human breast carcinoma cells and blood lymphocytes following photon and proton exposures. RADIATION AND ENVIRONMENTAL BIOPHYSICS 2023; 62:151-160. [PMID: 36763142 PMCID: PMC9950189 DOI: 10.1007/s00411-023-01016-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Accepted: 01/15/2023] [Indexed: 06/18/2023]
Abstract
Breast carcinomas (BC) are among the most frequent cancers in women. Studies on radiosensitivity and ionizing radiation response of BC cells are scarce and mainly focused on intrinsic molecular mechanisms but do not include clinically relevant features as chromosomal rearrangements important for radiotherapy. The main purpose of this study was to compare the ionizing radiation response and efficiency of repair mechanisms of human breast carcinoma cells (Cal 51) and peripheral blood lymphocytes (PBL) for different doses and radiation qualities (60Co γ-rays, 150 MeV and spread-out Bragg peak (SOBP) proton beams). The radiation response functions obtained using the conventional metaphase assay and premature chromosome condensation (PCC) technique enabled us to determine the number of chromosomal breaks at different time after irradiation. Both cytogenetic assays used confirmed the higher biological radiosensitivity for proton beams in tumor cells compared to PBL, corresponding to higher values of the linear LQ parameter α. additionally, the ratio of the LQ parameters β/α describing efficiency of the repair mechanisms, obtained for chromosome aberrations, showed higher numbers for PBL than for Cal 51 for all exposures. Similar results were observed for the ratio of PCC breaks determined directly after irradiation to that obtained 12 h later. This parameter (t0/t12) showed faster decrease of the repair efficiency with increasing LET value for Cal 51 cells. This finding supports the use of the proton therapy for breast cancer patients.
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Affiliation(s)
- Agata Kowalska
- Institute of Mathematics, Physics and Chemistry, Maritime University of Szczecin, Wały Chrobrego 1, 2, 70-500, Szczecin, Poland.
| | - Elena Nasonova
- Joint Institute for Nuclear Research, Joliot-Curie 6, 141980, Dubna, Russia
| | - Polina Kutsalo
- Joint Institute for Nuclear Research, Joliot-Curie 6, 141980, Dubna, Russia
| | - Konrad Czerski
- Institute of Physics, University of Szczecin, ul. Wielkopolska 15, 70-451, Szczecin, Poland
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Dutta A, Mitra J, Hegde PM, Mitra S, Hegde ML. Characterizing the Repair of DNA Double-Strand Breaks: A Review of Surrogate Plasmid-Based Reporter Methods. Methods Mol Biol 2023; 2701:173-182. [PMID: 37574482 DOI: 10.1007/978-1-0716-3373-1_11] [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] [Indexed: 08/15/2023]
Abstract
DNA double-strand breaks (DSBs) are the most lethal genomic lesions that are induced endogenously during physiological reactions as well as by external stimuli and genotoxicants. DSBs are repaired in mammalian cells via one of three well-studied pathways depending on the cell cycle status and/or the nature of the break. First, the homologous recombination (HR) pathway utilizes the duplicated sister chromatid as a template in S/G2 cells. Second, the nonhomologous end-joining (NHEJ) is the predominant DSB repair pathway throughout the cell cycle. The third pathway, microhomology-mediated/alternative end-joining (MMEJ/Alt-EJ), is a specialized backup pathway that works not only in the S phase but also in G0/G1 cells that constitute the bulk of human tissues. In vitro experimental methods to recapitulate the repair of physiologically relevant DSBs pose a challenge. Commonly employed plasmid- or oligonucleotide-based substrates contain restriction enzyme-cleaved DSB mimics, which undoubtedly do not mimic DSB ends generated by ionizing radiation (IR), chemotherapeutics, and reactive oxygen species (ROS). DSBs can also be indirectly generated by reactive oxygen species (ROS). All such DSBs invariably contain blocked termini. In this methodology chapter, we describe a method to recapitulate the DSB repair mechanism using in cellulo and in vitro cell-free systems. This methodology enables researchers to assess the contribution of NHEJ vs. Alt-EJ using a reporter plasmid containing DSB lesions with non-ligatable termini. Limitations and challenges of prevailing methods are also addressed.
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Affiliation(s)
- Arijit Dutta
- Department of Biochemistry and Structural Biology, The University of Texas Health Science Center at San Antonio, San Antonio, TX, USA.
| | - Joy Mitra
- Division of DNA Repair Research, Center for Neuroregeneration, Department of Neurosurgery, Houston Methodist Research Institute, Houston, TX, USA
| | - Pavana M Hegde
- Division of DNA Repair Research, Center for Neuroregeneration, Department of Neurosurgery, Houston Methodist Research Institute, Houston, TX, USA
| | - Sankar Mitra
- Division of DNA Repair Research, Center for Neuroregeneration, Department of Neurosurgery, Houston Methodist Research Institute, Houston, TX, USA
| | - Muralidhar L Hegde
- Division of DNA Repair Research, Center for Neuroregeneration, Department of Neurosurgery, Houston Methodist Research Institute, Houston, TX, USA.
- Department of Neurosciences, Weill Cornell Medical College, New York, NY, USA.
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Ul Haq SI, Zheng D, Feng N, Jiang X, Qiao F, He JS, Qiu QS. Progresses of CRISPR/Cas9 genome editing in forage crops. JOURNAL OF PLANT PHYSIOLOGY 2022; 279:153860. [PMID: 36371870 DOI: 10.1016/j.jplph.2022.153860] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Accepted: 11/02/2022] [Indexed: 06/16/2023]
Abstract
The clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9) mediated-genome editing has evolved into a powerful tool that is widely used in plant species to induce editing in the genome for analyzing gene function and crop improvement. CRISPR/Cas9 is an RNA-guided genome editing tool consisting of a Cas9 nuclease and a single-guide RNA (sgRNA). The CRISPR/Cas9 system enables more accurate and efficient genome editing in crops. In this review, we summarized the advances of the CRISPR/Cas9 technology in plant genome editing and its applications in forage crops. We described briefly about the development of CRISPR/Cas9 technology in plant genome editing. We assessed the progress of CRISPR/Cas9-mediated targeted-mutagenesis in various forage crops, including alfalfa, Medicago truncatula, Hordeum vulgare, Sorghum bicolor, Setaria italica and Panicum virgatum. The potentials and challenges of CRISPR/Cas9 in forage breeding were discussed.
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Affiliation(s)
- Syed Inzimam Ul Haq
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, Gansu, 730000, China
| | - Dianfeng Zheng
- College of Coastal Agricultural Sciences, Guangdong Ocean University, Zhanjiang, Guangdong, 524088, China
| | - Naijie Feng
- College of Coastal Agricultural Sciences, Guangdong Ocean University, Zhanjiang, Guangdong, 524088, China
| | - Xingyu Jiang
- College of Coastal Agricultural Sciences, Guangdong Ocean University, Zhanjiang, Guangdong, 524088, China
| | - Feng Qiao
- Academy of Plateau Science and Sustainability, School of Life Sciences, Qinghai Normal University, Xining, Qinghai, 810016, China
| | - Jin-Sheng He
- State Key Laboratory of Herbage Improvement and Grassland Agro-ecosystems, Lanzhou University, Lanzhou, Gansu, 730000, China
| | - Quan-Sheng Qiu
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, Gansu, 730000, China; State Key Laboratory of Herbage Improvement and Grassland Agro-ecosystems, Lanzhou University, Lanzhou, Gansu, 730000, China; Academy of Plateau Science and Sustainability, School of Life Sciences, Qinghai Normal University, Xining, Qinghai, 810016, China; College of Coastal Agricultural Sciences, Guangdong Ocean University, Zhanjiang, Guangdong, 524088, China.
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7
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Zhang S, Wu S, Hu C, Yang Q, Dong T, Sheng O, Deng G, He W, Dou T, Li C, Sun C, Yi G, Bi F. Increased mutation efficiency of CRISPR/Cas9 genome editing in banana by optimized construct. PeerJ 2022; 10:e12664. [PMID: 35036088 PMCID: PMC8742547 DOI: 10.7717/peerj.12664] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Accepted: 11/30/2021] [Indexed: 01/07/2023] Open
Abstract
The CRISPR/Cas9-mediated genome editing system has been used extensively to engineer targeted mutations in a wide variety of species. Its application in banana, however, has been hindered because of the species' triploid nature and low genome editing efficiency. This has delayed the development of a DNA-free genome editing approach. In this study, we reported that the endogenous U6 promoter and banana codon-optimized Cas9 apparently increased mutation frequency in banana, and we generated a method to validate the mutation efficiency of the CRISPR/Cas9-mediated genome editing system based on transient expression in protoplasts. The activity of the MaU6c promoter was approximately four times higher than that of the OsU6a promoter in banana protoplasts. The application of this promoter and banana codon-optimized Cas9 in CRISPR/Cas9 cassette resulted in a fourfold increase in mutation efficiency compared with the previous CRISPR/Cas9 cassette for banana. Our results indicated that the optimized CRISPR/Cas9 system was effective for mutating targeted genes in banana and thus will improve the applications for basic functional genomics. These findings are relevant to future germplasm improvement and provide a foundation for developing DNA-free genome editing technology in banana.
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Affiliation(s)
- Sen Zhang
- Key Laboratory of South Subtropical Fruit Biology and Genetic Resource Utilization (Ministry of Agriculture and Rural Affairs), Guangdong Key Laboratory of Tropical and Subtropical Fruit Tree Research, Institute of Fruit Tree Research, Guangdong Academy of Agricultural Sciences, Guangzhou, Guangdong, China,College of Horticulture and Forestry Sciences, Huazhong Agricultural University, Wuhan, Hubei, China
| | - Shaoping Wu
- Key Laboratory of South Subtropical Fruit Biology and Genetic Resource Utilization (Ministry of Agriculture and Rural Affairs), Guangdong Key Laboratory of Tropical and Subtropical Fruit Tree Research, Institute of Fruit Tree Research, Guangdong Academy of Agricultural Sciences, Guangzhou, Guangdong, China,College of Life Sciences, Zhaoqing University, Zhaoqing, Guangdong, China
| | - Chunhua Hu
- Key Laboratory of South Subtropical Fruit Biology and Genetic Resource Utilization (Ministry of Agriculture and Rural Affairs), Guangdong Key Laboratory of Tropical and Subtropical Fruit Tree Research, Institute of Fruit Tree Research, Guangdong Academy of Agricultural Sciences, Guangzhou, Guangdong, China
| | - Qiaosong Yang
- Key Laboratory of South Subtropical Fruit Biology and Genetic Resource Utilization (Ministry of Agriculture and Rural Affairs), Guangdong Key Laboratory of Tropical and Subtropical Fruit Tree Research, Institute of Fruit Tree Research, Guangdong Academy of Agricultural Sciences, Guangzhou, Guangdong, China
| | - Tao Dong
- Key Laboratory of South Subtropical Fruit Biology and Genetic Resource Utilization (Ministry of Agriculture and Rural Affairs), Guangdong Key Laboratory of Tropical and Subtropical Fruit Tree Research, Institute of Fruit Tree Research, Guangdong Academy of Agricultural Sciences, Guangzhou, Guangdong, China
| | - Ou Sheng
- Key Laboratory of South Subtropical Fruit Biology and Genetic Resource Utilization (Ministry of Agriculture and Rural Affairs), Guangdong Key Laboratory of Tropical and Subtropical Fruit Tree Research, Institute of Fruit Tree Research, Guangdong Academy of Agricultural Sciences, Guangzhou, Guangdong, China
| | - Guiming Deng
- Key Laboratory of South Subtropical Fruit Biology and Genetic Resource Utilization (Ministry of Agriculture and Rural Affairs), Guangdong Key Laboratory of Tropical and Subtropical Fruit Tree Research, Institute of Fruit Tree Research, Guangdong Academy of Agricultural Sciences, Guangzhou, Guangdong, China
| | - Weidi He
- Key Laboratory of South Subtropical Fruit Biology and Genetic Resource Utilization (Ministry of Agriculture and Rural Affairs), Guangdong Key Laboratory of Tropical and Subtropical Fruit Tree Research, Institute of Fruit Tree Research, Guangdong Academy of Agricultural Sciences, Guangzhou, Guangdong, China
| | - Tongxin Dou
- Key Laboratory of South Subtropical Fruit Biology and Genetic Resource Utilization (Ministry of Agriculture and Rural Affairs), Guangdong Key Laboratory of Tropical and Subtropical Fruit Tree Research, Institute of Fruit Tree Research, Guangdong Academy of Agricultural Sciences, Guangzhou, Guangdong, China
| | - Chunyu Li
- Key Laboratory of South Subtropical Fruit Biology and Genetic Resource Utilization (Ministry of Agriculture and Rural Affairs), Guangdong Key Laboratory of Tropical and Subtropical Fruit Tree Research, Institute of Fruit Tree Research, Guangdong Academy of Agricultural Sciences, Guangzhou, Guangdong, China
| | - Chenkang Sun
- Key Laboratory of South Subtropical Fruit Biology and Genetic Resource Utilization (Ministry of Agriculture and Rural Affairs), Guangdong Key Laboratory of Tropical and Subtropical Fruit Tree Research, Institute of Fruit Tree Research, Guangdong Academy of Agricultural Sciences, Guangzhou, Guangdong, China,College of Life Sciences, South China Agricultural University, Guangzhou, Guangdong
| | - Ganjun Yi
- Key Laboratory of South Subtropical Fruit Biology and Genetic Resource Utilization (Ministry of Agriculture and Rural Affairs), Guangdong Key Laboratory of Tropical and Subtropical Fruit Tree Research, Institute of Fruit Tree Research, Guangdong Academy of Agricultural Sciences, Guangzhou, Guangdong, China
| | - Fangcheng Bi
- Key Laboratory of South Subtropical Fruit Biology and Genetic Resource Utilization (Ministry of Agriculture and Rural Affairs), Guangdong Key Laboratory of Tropical and Subtropical Fruit Tree Research, Institute of Fruit Tree Research, Guangdong Academy of Agricultural Sciences, Guangzhou, Guangdong, China
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Wu Y, Yuan Q, Zhu Y, Gao X, Song J, Yin Z. Improving FnCas12a Genome Editing by Exonuclease Fusion. CRISPR J 2021; 3:503-511. [PMID: 33346706 DOI: 10.1089/crispr.2020.0073] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Among current reported Cas12a orthologs, Francisella novicida Cas12a (FnCas12a) is less restricted by protospacer adjacent motif (PAM). However, the activity of FnCas12a nuclease is relatively low or undetectable in human cells, limiting its application as desirable genome engineering tools. Here, we describe TEXT (Tethering EXonuclease T5 with FnCas12a)-a fusion strategy that significantly increased the knockout efficiency of FnCas12a in human cells at multiple genomic loci in three different cell lines. TEXT results in higher insertion and deletion efficiency than FnCas12a under different spacer lengths from 18 nt to 23 nt. Deep sequencing shows that TEXT substantially increased the deletion frequency and deletion size at the targeted locus. Compared to other Cas12a orthologs, including AsCas12a and LbCas12a, TEXT achieves the highest on-targeting efficiency and shows minimal off-targeting effects at all tested sites. TEXT enhances the activity of FnCas12a nuclease and expands its targeting scope and efficiency in human cell genome engineering.
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Affiliation(s)
- Yongqiang Wu
- Gene Editing Research Center, Hebei University of Science and Technology, Shijiazhuang, PR China; Hebei University of Science and Technology, Shijiazhuang, PR China
| | - Qichen Yuan
- Department of Chemical and Biomolecular Engineering, Rice University, Houston, Texas, USA; Hebei University of Science and Technology, Shijiazhuang, PR China
| | - Yufeng Zhu
- Institute for Science and Technology Development, Hebei University of Science and Technology, Shijiazhuang, PR China; Hebei University of Science and Technology, Shijiazhuang, PR China
| | - Xiang Gao
- School of Environmental Science and Engineering, Hebei University of Science and Technology, Shijiazhuang, PR China; Hebei University of Science and Technology, Shijiazhuang, PR China
| | - Jiabao Song
- Department of Bioscience and Bioengineering, Hebei University of Science and Technology, Shijiazhuang, China; and Hebei University of Science and Technology, Shijiazhuang, PR China
| | - Ziru Yin
- Periodical Press, Hebei University of Science and Technology, Shijiazhuang, PR China
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Hsu CT, Yuan YH, Lin YC, Lin S, Cheng QW, Wu FH, Sheen J, Shih MC, Lin CS. Efficient and Economical Targeted Insertion in Plant Genomes via Protoplast Regeneration. CRISPR J 2021; 4:752-760. [PMID: 34569819 PMCID: PMC9639242 DOI: 10.1089/crispr.2021.0045] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Versatile genome editing can be facilitated by the insertion of DNA sequences into specific locations. Current protocols involving CRISPR and Cas proteins rely on low efficiency homology-directed repair or non-homologous end joining with modified double-stranded DNA oligonucleotides as donors. Our simple protocol eliminates the need for expensive equipment, chemical and enzymatic donor DNA modification, or plasmid construction by using polyethylene glycol-calcium to deliver non-modified single-stranded DNA oligonucleotides and CRISPR-Cas9 ribonucleoprotein into protoplasts. Plants regenerated via edited protoplasts achieved targeted insertion frequencies of up to 50% in Nicotiana benthamiana and 13.6% in rapid cycling Brassica oleracea without antibiotic selection. Using a 60 nt donor containing 27 nt in each homologous arm, 6/22 regenerated N. benthamiana plants showed targeted insertions, and one contained a precise insertion of a 6 bp HindIII site. The inserted sequences were transmitted to the next generation and invite the possibility of future exploration of versatile genome editing by targeted DNA insertion in plants.
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Affiliation(s)
- Chen-Tran Hsu
- Agricultural Biotechnology Research Center, Academia Sinica, Taipei, Taiwan; Harvard Medical School, Boston, Massachusetts, USA
| | - Yu-Hsuan Yuan
- Agricultural Biotechnology Research Center, Academia Sinica, Taipei, Taiwan; Harvard Medical School, Boston, Massachusetts, USA
| | - Yao-Cheng Lin
- Agricultural Biotechnology Research Center, Academia Sinica, Taipei, Taiwan; Harvard Medical School, Boston, Massachusetts, USA
| | - Steven Lin
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan; Harvard Medical School, Boston, Massachusetts, USA
| | - Qiao-Wei Cheng
- Agricultural Biotechnology Research Center, Academia Sinica, Taipei, Taiwan; Harvard Medical School, Boston, Massachusetts, USA
| | - Fu-Hui Wu
- Agricultural Biotechnology Research Center, Academia Sinica, Taipei, Taiwan; Harvard Medical School, Boston, Massachusetts, USA
| | - Jen Sheen
- Department of Molecular Biology and Centre for Computational and Integrative Biology, Massachusetts General Hospital, Boston, Massachusetts, USA; and Harvard Medical School, Boston, Massachusetts, USA
- Department of Genetics, Harvard Medical School, Boston, Massachusetts, USA
| | - Ming-Che Shih
- Agricultural Biotechnology Research Center, Academia Sinica, Taipei, Taiwan; Harvard Medical School, Boston, Massachusetts, USA
| | - Choun-Sea Lin
- Agricultural Biotechnology Research Center, Academia Sinica, Taipei, Taiwan; Harvard Medical School, Boston, Massachusetts, USA
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10
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Sattar MN, Iqbal Z, Al-Khayri JM, Jain SM. Induced Genetic Variations in Fruit Trees Using New Breeding Tools: Food Security and Climate Resilience. PLANTS (BASEL, SWITZERLAND) 2021; 10:1347. [PMID: 34371550 PMCID: PMC8309169 DOI: 10.3390/plants10071347] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/22/2021] [Revised: 06/23/2021] [Accepted: 06/28/2021] [Indexed: 12/22/2022]
Abstract
Fruit trees provide essential nutrients to humans by contributing to major agricultural outputs and economic growth globally. However, major constraints to sustainable agricultural productivity are the uncontrolled proliferation of the population, and biotic and abiotic stresses. Tree mutation breeding has been substantially improved using different physical and chemical mutagens. Nonetheless, tree plant breeding has certain crucial bottlenecks including a long life cycle, ploidy level, occurrence of sequence polymorphisms, nature of parthenocarpic fruit development and linkage. Genetic engineering of trees has focused on boosting quality traits such as productivity, wood quality, and resistance to biotic and abiotic stresses. Recent technological advances in genome editing provide a unique opportunity for the genetic improvement of woody plants. This review examines application of the CRISPR-Cas system to reduce disease susceptibility, alter plant architecture, enhance fruit quality, and improve yields. Examples are discussed of the contemporary CRISPR-Cas system to engineer easily scorable PDS genes, modify lignin, and to alter the flowering onset, fertility, tree architecture and certain biotic stresses.
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Affiliation(s)
- Muhammad Naeem Sattar
- Central Laboratories, King Faisal University, Al-Ahsa 31982, Saudi Arabia; (M.N.S.); (Z.I.)
| | - Zafar Iqbal
- Central Laboratories, King Faisal University, Al-Ahsa 31982, Saudi Arabia; (M.N.S.); (Z.I.)
| | - Jameel M. Al-Khayri
- Department of Agricultural Biotechnology, College of Agriculture and Food Sciences, King Faisal University, Al-Ahsa 31982, Saudi Arabia
| | - S. Mohan Jain
- Department of Agricultural Sciences, PL-27, University of Helsinki, 00014 Helsinki, Finland;
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Tatin X, Muggiolu G, Sauvaigo S, Breton J. Evaluation of DNA double-strand break repair capacity in human cells: Critical overview of current functional methods. MUTATION RESEARCH. REVIEWS IN MUTATION RESEARCH 2021; 788:108388. [PMID: 34893153 DOI: 10.1016/j.mrrev.2021.108388] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Revised: 06/17/2021] [Accepted: 06/23/2021] [Indexed: 02/05/2023]
Abstract
DNA double-strand breaks (DSBs) are highly deleterious lesions, responsible for mutagenesis, chromosomal translocation or cell death. DSB repair (DSBR) is therefore a critical part of the DNA damage response (DDR) to restore molecular and genomic integrity. In humans, this process is achieved through different pathways with various outcomes. The balance between DSB repair activities varies depending on cell types, tissues or individuals. Over the years, several methods have been developed to study variations in DSBR capacity. Here, we mainly focus on functional techniques, which provide dynamic information regarding global DSB repair proficiency or the activity of specific pathways. These methods rely on two kinds of approaches. Indirect techniques, such as pulse field gel electrophoresis (PFGE), the comet assay and immunofluorescence (IF), measure DSB repair capacity by quantifying the time-dependent decrease in DSB levels after exposure to a DNA-damaging agent. On the other hand, cell-free assays and reporter-based methods directly track the repair of an artificial DNA substrate. Each approach has intrinsic advantages and limitations and despite considerable efforts, there is currently no ideal method to quantify DSBR capacity. All techniques provide different information and can be regarded as complementary, but some studies report conflicting results. Parameters such as the type of biological material, the required equipment or the cost of analysis may also limit available options. Improving currently available methods measuring DSBR capacity would be a major step forward and we present direct applications in mechanistic studies, drug development, human biomonitoring and personalized medicine, where DSBR analysis may improve the identification of patients eligible for chemo- and radiotherapy.
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Affiliation(s)
- Xavier Tatin
- Univ. Grenoble Alpes, CEA, CNRS, IRIG, SyMMES, 38000 Grenoble, France; LXRepair, 5 Avenue du Grand Sablon, 38700 La Tronche, France
| | | | - Sylvie Sauvaigo
- LXRepair, 5 Avenue du Grand Sablon, 38700 La Tronche, France
| | - Jean Breton
- Univ. Grenoble Alpes, CEA, CNRS, IRIG, SyMMES, 38000 Grenoble, France.
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12
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Toy HI, Karakülah G, Kontou PI, Alotaibi H, Georgakilas AG, Pavlopoulou A. Investigating Molecular Determinants of Cancer Cell Resistance to Ionizing Radiation Through an Integrative Bioinformatics Approach. Front Cell Dev Biol 2021; 9:620248. [PMID: 33898418 PMCID: PMC8058375 DOI: 10.3389/fcell.2021.620248] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Accepted: 03/15/2021] [Indexed: 12/13/2022] Open
Abstract
Eradication of cancer cells through exposure to high doses of ionizing radiation (IR) is a widely used therapeutic strategy in the clinical setting. However, in many cases, cancer cells can develop remarkable resistance to radiation. Radioresistance represents a prominent obstacle in the effective treatment of cancer. Therefore, elucidation of the molecular mechanisms and pathways related to radioresistance in cancer cells is of paramount importance. In the present study, an integrative bioinformatics approach was applied to three publicly available RNA sequencing and microarray transcriptome datasets of human cancer cells of different tissue origins treated with ionizing radiation. These data were investigated in order to identify genes with a significantly altered expression between radioresistant and corresponding radiosensitive cancer cells. Through rigorous statistical and biological analyses, 36 genes were identified as potential biomarkers of radioresistance. These genes, which are primarily implicated in DNA damage repair, oxidative stress, cell pro-survival, and apoptotic pathways, could serve as potential diagnostic/prognostic markers cancer cell resistance to radiation treatment, as well as for therapy outcome and cancer patient survival. In addition, our findings could be potentially utilized in the laboratory and clinical setting for enhancing cancer cell susceptibility to radiation therapy protocols.
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Affiliation(s)
- Halil Ibrahim Toy
- Izmir Biomedicine and Genome Center, Izmir, Turkey.,Izmir International Biomedicine and Genome Institute, Dokuz Eylül University, Izmir, Turkey
| | - Gökhan Karakülah
- Izmir Biomedicine and Genome Center, Izmir, Turkey.,Izmir International Biomedicine and Genome Institute, Dokuz Eylül University, Izmir, Turkey
| | - Panagiota I Kontou
- Department of Computer Science and Biomedical Informatics, University of Thessaly, Lamia, Greece
| | - Hani Alotaibi
- Izmir Biomedicine and Genome Center, Izmir, Turkey.,Izmir International Biomedicine and Genome Institute, Dokuz Eylül University, Izmir, Turkey
| | - Alexandros G Georgakilas
- DNA Damage Laboratory, Department of Physics, School of Applied Mathematical and Physical Sciences, Zografou, National Technical University of Athens, Athens, Greece
| | - Athanasia Pavlopoulou
- Izmir Biomedicine and Genome Center, Izmir, Turkey.,Izmir International Biomedicine and Genome Institute, Dokuz Eylül University, Izmir, Turkey
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13
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Stinson BM, Loparo JJ. Repair of DNA Double-Strand Breaks by the Nonhomologous End Joining Pathway. Annu Rev Biochem 2021; 90:137-164. [PMID: 33556282 DOI: 10.1146/annurev-biochem-080320-110356] [Citation(s) in RCA: 85] [Impact Index Per Article: 28.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
DNA double-strand breaks pose a serious threat to genome stability. In vertebrates, these breaks are predominantly repaired by nonhomologous end joining (NHEJ), which pairs DNA ends in a multiprotein synaptic complex to promote their direct ligation. NHEJ is a highly versatile pathway that uses an array of processing enzymes to modify damaged DNA ends and enable their ligation. The mechanisms of end synapsis and end processing have important implications for genome stability. Rapid and stable synapsis is necessary to limit chromosome translocations that result from the mispairing of DNA ends. Furthermore, end processing must be tightly regulated to minimize mutations at the break site. Here, we review our current mechanistic understanding of vertebrate NHEJ, with a particular focus on end synapsis and processing.
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Affiliation(s)
- Benjamin M Stinson
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts 02115, USA; ,
| | - Joseph J Loparo
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, Massachusetts 02115, USA; ,
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14
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Xu X, Yuan Y, Feng B, Deng W. CRISPR/Cas9-mediated gene-editing technology in fruit quality improvement. FOOD QUALITY AND SAFETY 2020. [DOI: 10.1093/fqsafe/fyaa028] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Abstract
Fruits are an essential part of a healthy, balanced diet and it is particularly important for fibre, essential vitamins, and trace elements. Improvement in the quality of fruit and elongation of shelf life are crucial goals for researchers. However, traditional techniques have some drawbacks, such as long period, low efficiency, and difficulty in the modification of target genes, which limit the progress of the study. Recently, the clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 technique was developed and has become the most popular gene-editing technology with high efficiency, simplicity, and low cost. CRISPR/Cas9 technique is widely accepted to analyse gene function and complete genetic modification. This review introduces the latest progress of CRISPR/Cas9 technology in fruit quality improvement. For example, CRISPR/Cas9-mediated targeted mutagenesis of RIPENING INHIBITOR gene (RIN), Lycopene desaturase (PDS), Pectate lyases (PL), SlMYB12, and CLAVATA3 (CLV3) can affect fruit ripening, fruit bioactive compounds, fruit texture, fruit colouration, and fruit size. CRISPR/Cas9-mediated mutagenesis has become an efficient method to modify target genes and improve fruit quality.
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Affiliation(s)
- Xin Xu
- Key Laboratory of Plant Hormones and Development Regulation of Chongqing, School of Life Sciences, Chongqing University, Chongqing, China
| | - Yujin Yuan
- Key Laboratory of Plant Hormones and Development Regulation of Chongqing, School of Life Sciences, Chongqing University, Chongqing, China
| | - Bihong Feng
- College of Agriculture, Guangxi University, Nanning, China
| | - Wei Deng
- Key Laboratory of Plant Hormones and Development Regulation of Chongqing, School of Life Sciences, Chongqing University, Chongqing, China
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15
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Zhou J, Li D, Wang G, Wang F, Kunjal M, Joldersma D, Liu Z. Application and future perspective of CRISPR/Cas9 genome editing in fruit crops. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2020. [PMID: 30791200 DOI: 10.1111/jipb.1279] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Fruit crops, including apple, orange, grape, banana, strawberry, watermelon, kiwifruit and tomato, not only provide essential nutrients for human life but also contribute to the major agricultural output and economic growth of many countries and regions in the world. Recent advancements in genome editing provides an unprecedented opportunity for the genetic improvement of these agronomically important fruit crops. Here, we summarize recent reports of applying CRISPR/Cas9 to fruit crops, including efforts to reduce disease susceptibility, change plant architecture or flower morphology, improve fruit quality traits, and increase fruit yield. We discuss challenges facing fruit crops as well as new improvements and platforms that could be used to facilitate genome editing in fruit crops, including dCas9-base-editing to introduce desirable alleles and heat treatment to increase editing efficiency. In addition, we highlight what we see as potentially revolutionary development ranging from transgene-free genome editing to de novo domestication of wild relatives. Without doubt, we now see only the beginning of what will eventually be possible with the use of the CRISPR/Cas9 toolkit. Efforts to communicate with the public and an emphasis on the manipulation of consumer-friendly traits will be critical to facilitate public acceptance of genetically engineered fruits with this new technology.
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Affiliation(s)
- Junhui Zhou
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD, 20742, USA
| | - Dongdong Li
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD, 20742, USA
- Zhejiang Key Laboratory for Agri-Food Processing, Zhejiang University, Hangzhou, 310058, China
| | - Guoming Wang
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD, 20742, USA
- State Key Laboratory of Crop Genetics and Germplasm Enhancement, Centre of Pear Engineering Technology Research, Nanjing Agricultural University, Nanjing, 210095, China
| | - Fuxi Wang
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD, 20742, USA
| | - Merixia Kunjal
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD, 20742, USA
| | - Dirk Joldersma
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD, 20742, USA
| | - Zhongchi Liu
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD, 20742, USA
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16
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Zhou J, Li D, Wang G, Wang F, Kunjal M, Joldersma D, Liu Z. Application and future perspective of CRISPR/Cas9 genome editing in fruit crops. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2020; 62:269-286. [PMID: 30791200 PMCID: PMC6703982 DOI: 10.1111/jipb.12793] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2018] [Accepted: 02/18/2019] [Indexed: 05/24/2023]
Abstract
Fruit crops, including apple, orange, grape, banana, strawberry, watermelon, kiwifruit and tomato, not only provide essential nutrients for human life but also contribute to the major agricultural output and economic growth of many countries and regions in the world. Recent advancements in genome editing provides an unprecedented opportunity for the genetic improvement of these agronomically important fruit crops. Here, we summarize recent reports of applying CRISPR/Cas9 to fruit crops, including efforts to reduce disease susceptibility, change plant architecture or flower morphology, improve fruit quality traits, and increase fruit yield. We discuss challenges facing fruit crops as well as new improvements and platforms that could be used to facilitate genome editing in fruit crops, including dCas9-base-editing to introduce desirable alleles and heat treatment to increase editing efficiency. In addition, we highlight what we see as potentially revolutionary development ranging from transgene-free genome editing to de novo domestication of wild relatives. Without doubt, we now see only the beginning of what will eventually be possible with the use of the CRISPR/Cas9 toolkit. Efforts to communicate with the public and an emphasis on the manipulation of consumer-friendly traits will be critical to facilitate public acceptance of genetically engineered fruits with this new technology.
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Affiliation(s)
- Junhui Zhou
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD 20742, USA
| | - Dongdong Li
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD 20742, USA
- Zhejiang Key Laboratory for Agri-Food Processing, Zhejiang University, Hangzhou 310058, China
| | - Guoming Wang
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD 20742, USA
- State Key Laboratory of Crop Genetics and Germplasm Enhancement, Centre of Pear Engineering Technology
Research, Nanjing Agricultural University, Nanjing 210095, China
| | - Fuxi Wang
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD 20742, USA
| | - Merixia Kunjal
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD 20742, USA
| | - Dirk Joldersma
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD 20742, USA
| | - Zhongchi Liu
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD 20742, USA
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17
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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: 50] [Impact Index Per Article: 10.0] [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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18
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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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19
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Laporte GA, Leguisamo NM, Kalil AN, Saffi J. Clinical importance of DNA repair in sporadic colorectal cancer. Crit Rev Oncol Hematol 2018; 126:168-185. [PMID: 29759559 DOI: 10.1016/j.critrevonc.2018.03.017] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2017] [Revised: 03/05/2018] [Accepted: 03/22/2018] [Indexed: 12/18/2022] Open
Abstract
Colorectal cancer (CRC) is the third major cause of cancer-related deaths worldwide. However, despite the scientific efforts to provide a molecular classification to improve CRC clinical practice management, prognosis and therapeutic decision are still strongly dependent on the TNM staging system. Mismatch repair system deficiencies can occur in many organs, but it is mainly a hallmark of CRC influencing clinical outcomes and response to therapy. This review will discuss the effect of the modulation of other DNA repair pathways (direct, excision and double strand break repairs) in the clinical and pathological aspects of colorectal cancer and its potential as prognostic and predictive biomarkers.
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Affiliation(s)
- Gustavo A Laporte
- Surgical Oncology Service, Santa Casa de Misericórdia de Porto Alegre (ISCMPA), Universidade Federal de Ciências da Saúde de Porto Alegre (UFCSPA), Porto Alegre, Rio Grande do Sul, Brazil
| | - Natalia M Leguisamo
- Institute of Cardiology/University Foundation of Cardiology, Porto Alegre, Rio Grande do Sul, Brazil; Laboratory of Genetic Toxicology, Universidade Federal de Ciências da Saúde de Porto Alegre (UFCSPA), Porto Alegre, Rio Grande do Sul, Brazil
| | - Antonio N Kalil
- Surgical Oncology Service, Santa Casa de Misericórdia de Porto Alegre (ISCMPA), Universidade Federal de Ciências da Saúde de Porto Alegre (UFCSPA), Porto Alegre, Rio Grande do Sul, Brazil
| | - Jenifer Saffi
- Laboratory of Genetic Toxicology, Universidade Federal de Ciências da Saúde de Porto Alegre (UFCSPA), Porto Alegre, Rio Grande do Sul, Brazil.
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20
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Senoptosis: non-lethal DNA cleavage as a route to deep senescence. Oncotarget 2018; 8:30656-30671. [PMID: 28427150 PMCID: PMC5458157 DOI: 10.18632/oncotarget.15693] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2016] [Accepted: 02/06/2017] [Indexed: 11/25/2022] Open
Abstract
DNA-damage-induced apoptosis and cellular senescence are perceived as two distinct cell fates. We found that after ionizing radiation (IR)-induced DNA damage the majority (up to 70 %) of senescent human diploid fibroblasts (HDFs) were subjected to controlled cleavage of DNA, resulting in the establishment of a viable and stable sub-G1 population, i.e. deeply senescent cells. We show that in senescent HDFs this DNA cleavage is triggered by modest loss of the mitochondrial membrane potential, which is not sufficient to activate caspases, but strong enough to release mitochondrial endonuclease G (EndoG). We demonstrate that upon γ-irradiation in HDFs EndoG translocates into the nucleus playing an essential role in the non-lethal cleavage of damaged DNA. Notably, the established sub-G1 cell population does not contribute to the senescence-associated secretory phenotype (SASP), however, it exhibits increased senescence-associated β-galactosidase activity. We show that EndoG knockdown causes an increase in DNA damage, indicating a role of this enzyme in DNA repair. Thus, we conclude that IR-induced deep senescence of HDFs exhibits features of both senescence, such as cell cycle arrest and viability, and apoptosis like reduced DNA content and no SASP, and, resembles uncomplete or stalled apoptosis, a phenomenon we term senoptosis.
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21
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Abstract
Sequence-specific nucleases (SSNs) are nowadays fundamental tools to generate mutants that impaired in genes of interest. The bioactive molecules screened in the chemical genomics studies affect specific physiological process by disrupting the function of its target protein(s). Mutation analysis of the gene(s) of target protein(s) of the screened chemical is necessary to resolve how the chemical works in plants. Clustered regularly interspersed short palindromic repeats (CRISPR) from Prevotella and Francisella 1 (Cpf1) are newly characterized RNA-directed endonuclease. Several papers have shown clearly that Cpf1 could be a versatile SSN in plant genome engineering. Cfp1 from Francisella novicida (FnCpf1) recognizes TTN as its protospacer adjacent motif (PAM). FnCpf1 utilizes a shorter PAM compared to other known Cpf1s such as AsCpf1 or LbCpf1, which use TTTN as PAM. Since PAM length can be a limiting factor in target selection, this feature of FnCpf1 is practical for targeted mutagenesis experiments. The application of FnCpf1-mediated targeted mutagenesis to the chemical genomics could accelerate to figure out the mechanism of action of screened chemicals. Here, we describe procedures for targeted mutagenesis in rice and tobacco using FnCpf1.
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Affiliation(s)
- Akira Endo
- Plant Genome Engineering Research Unit, Institute of Agrobiological Sciences, National Agriculture and Food Research Organization, Tsukuba, Ibaraki, Japan
| | - Seiichi Toki
- Plant Genome Engineering Research Unit, Institute of Agrobiological Sciences, National Agriculture and Food Research Organization, Tsukuba, Ibaraki, Japan.
- Kihara Institute for Biological Research, Yokohama City University, Yokohama, Japan.
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22
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Telomere-Internal Double-Strand Breaks Are Repaired by Homologous Recombination and PARP1/Lig3-Dependent End-Joining. Cell Rep 2017; 17:1646-1656. [PMID: 27806302 DOI: 10.1016/j.celrep.2016.10.008] [Citation(s) in RCA: 64] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Revised: 09/06/2016] [Accepted: 10/03/2016] [Indexed: 01/29/2023] Open
Abstract
Shelterin protects chromosome ends from the DNA damage response. Although the mechanism of telomere protection has been studied extensively, the fate of double-strand breaks (DSBs) inside telomeres is not known. Here, we report that telomere-internal FokI-induced DSBs activate ATM kinase-dependent signaling in S-phase but are well tolerated and repaired efficiently. Homologous recombination contributes to repair, leading to increased telomere length heterogeneity typical of the alternative lengthening of telomeres (ALT) pathway. Furthermore, cells accumulate extra chromosomal telomeric signals (ECTS), a second hallmark of ALT. Telomere-internal DSBs are also repaired by a PARP1- and Ligase3-dependent reaction, suggesting alternative non-homologous end-joining (alt-NHEJ), which relies on microhomology at DSBs. However, as resected telomere-internal DSBs have perfect homology, their PARP1/Lig3-dependent end-joining may be more akin to single strand break repair. We conclude that shelterin does not repress ATM kinase signaling or DSB repair at telomere-internal sites, thereby allowing DNA repair to maintain telomere integrity.
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23
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Site-specific transfer of chromosomal segments and genes in wheat engineered chromosomes. J Genet Genomics 2017; 44:531-539. [DOI: 10.1016/j.jgg.2017.08.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2017] [Revised: 07/30/2017] [Accepted: 08/07/2017] [Indexed: 11/18/2022]
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24
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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: 33] [Impact Index Per Article: 4.7] [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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25
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Endo A, Masafumi M, Kaya H, Toki S. Efficient targeted mutagenesis of rice and tobacco genomes using Cpf1 from Francisella novicida. Sci Rep 2016; 6:38169. [PMID: 27905529 PMCID: PMC5131344 DOI: 10.1038/srep38169] [Citation(s) in RCA: 170] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Accepted: 11/04/2016] [Indexed: 12/19/2022] Open
Abstract
CRISPR/Cas9 systems are nowadays applied extensively to effect genome editing in various organisms including plants. CRISPR from Prevotella and Francisella 1 (Cpf1) is a newly characterized RNA-guided endonuclease that has two distinct features as compared to Cas9. First, Cpf1 utilizes a thymidine-rich protospacer adjacent motif (PAM) while Cas9 prefers a guanidine-rich PAM. Cpf1 could be used as a sequence-specific nuclease to target AT-rich regions of a genome that Cas9 had difficulty accessing. Second, Cpf1 generates DNA ends with a 5' overhang, whereas Cas9 creates blunt DNA ends after cleavage. "Sticky" DNA ends should increase the efficiency of insertion of a desired DNA fragment into the Cpf1-cleaved site using complementary DNA ends. Therefore, Cpf1 could be a potent tool for precise genome engineering. To evaluate whether Cpf1 can be applied to plant genome editing, we selected Cpf1 from Francisella novicida (FnCpf1), which recognizes a shorter PAM (TTN) within known Cpf1 proteins, and applied it to targeted mutagenesis in tobacco and rice. Our results show that targeted mutagenesis had occurred in transgenic plants expressing FnCpf1 with crRNA. Deletions of the targeted region were the most frequently observed mutations. Our results demonstrate that FnCpf1 can be applied successfully to genome engineering in plants.
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Affiliation(s)
- Akira Endo
- Plant Genome Engineering Research Unit, Institute of Agrobiological Sciences, National Agriculture and Food Research Organization, 2-1-2 Kannondai, Tsukuba, Ibaraki 305-8602, Japan
| | - Mikami Masafumi
- Plant Genome Engineering Research Unit, Institute of Agrobiological Sciences, National Agriculture and Food Research Organization, 2-1-2 Kannondai, Tsukuba, Ibaraki 305-8602, Japan
- Graduate School of Nanobioscience, Yokohama City University, 22-2 Seto, Yokohama, Kanagawa 236-0027, Japan
| | - Hidetaka Kaya
- Plant Genome Engineering Research Unit, Institute of Agrobiological Sciences, National Agriculture and Food Research Organization, 2-1-2 Kannondai, Tsukuba, Ibaraki 305-8602, Japan
| | - Seiichi Toki
- Plant Genome Engineering Research Unit, Institute of Agrobiological Sciences, National Agriculture and Food Research Organization, 2-1-2 Kannondai, Tsukuba, Ibaraki 305-8602, Japan
- Graduate School of Nanobioscience, Yokohama City University, 22-2 Seto, Yokohama, Kanagawa 236-0027, Japan
- Kihara Institute for Biological Research, Yokohama City University, 641-12 Maioka-cho, Yokohama, Kanagawa 244-0813, Japan
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26
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Zuo Z, Liu J. Cas9-catalyzed DNA Cleavage Generates Staggered Ends: Evidence from Molecular Dynamics Simulations. Sci Rep 2016; 5:37584. [PMID: 27874072 PMCID: PMC5118739 DOI: 10.1038/srep37584] [Citation(s) in RCA: 85] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Accepted: 10/31/2016] [Indexed: 12/26/2022] Open
Abstract
The CRISPR-associated endonuclease Cas9 from Streptococcus pyogenes (spCas9) along with a single guide RNA (sgRNA) has emerged as a versatile toolbox for genome editing. Despite recent advances in the mechanism studies on spCas9-sgRNA-mediated double-stranded DNA (dsDNA) recognition and cleavage, it is still unclear how the catalytic Mg2+ ions induce the conformation changes toward the catalytic active state. It also remains controversial whether Cas9 generates blunt-ended or staggered-ended breaks with overhangs in the DNA. To investigate these issues, here we performed the first all-atom molecular dynamics simulations of the spCas9-sgRNA-dsDNA system with and without Mg2+ bound. The simulation results showed that binding of two Mg2+ ions at the RuvC domain active site could lead to structurally and energetically favorable coordination ready for the non-target DNA strand cleavage. Importantly, we demonstrated with our simulations that Cas9-catalyzed DNA cleavage produces 1-bp staggered ends rather than generally assumed blunt ends.
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Affiliation(s)
- Zhicheng Zuo
- Department of Pharmaceutical Sciences, University of North Texas System College of Pharmacy, University of North Texas Health Science Center, Fort Worth, TX 76107, USA
| | - Jin Liu
- Department of Pharmaceutical Sciences, University of North Texas System College of Pharmacy, University of North Texas Health Science Center, Fort Worth, TX 76107, USA
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Woods ML, Barnes CP. Mechanistic Modelling and Bayesian Inference Elucidates the Variable Dynamics of Double-Strand Break Repair. PLoS Comput Biol 2016; 12:e1005131. [PMID: 27741226 PMCID: PMC5065155 DOI: 10.1371/journal.pcbi.1005131] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Accepted: 09/05/2016] [Indexed: 12/12/2022] Open
Abstract
DNA double-strand breaks are lesions that form during metabolism, DNA replication and exposure to mutagens. When a double-strand break occurs one of a number of repair mechanisms is recruited, all of which have differing propensities for mutational events. Despite DNA repair being of crucial importance, the relative contribution of these mechanisms and their regulatory interactions remain to be fully elucidated. Understanding these mutational processes will have a profound impact on our knowledge of genomic instability, with implications across health, disease and evolution. Here we present a new method to model the combined activation of non-homologous end joining, single strand annealing and alternative end joining, following exposure to ionising radiation. We use Bayesian statistics to integrate eight biological data sets of double-strand break repair curves under varying genetic knockouts and confirm that our model is predictive by re-simulating and comparing to additional data. Analysis of the model suggests that there are at least three disjoint modes of repair, which we assign as fast, slow and intermediate. Our results show that when multiple data sets are combined, the rate for intermediate repair is variable amongst genetic knockouts. Further analysis suggests that the ratio between slow and intermediate repair depends on the presence or absence of DNA-PKcs and Ku70, which implies that non-homologous end joining and alternative end joining are not independent. Finally, we consider the proportion of double-strand breaks within each mechanism as a time series and predict activity as a function of repair rate. We outline how our insights can be directly tested using imaging and sequencing techniques and conclude that there is evidence of variable dynamics in alternative repair pathways. Our approach is an important step towards providing a unifying theoretical framework for the dynamics of DNA repair processes.
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Affiliation(s)
- Mae L. Woods
- Department of Cell and Developmental Biology, University College London, London, England
| | - Chris P. Barnes
- Department of Cell and Developmental Biology, University College London, London, England
- Department of Genetics, Evolution and Environment, University College London, London, England
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Nakada S. Opposing roles of RNF8/RNF168 and deubiquitinating enzymes in ubiquitination-dependent DNA double-strand break response signaling and DNA-repair pathway choice. JOURNAL OF RADIATION RESEARCH 2016; 57 Suppl 1:i33-i40. [PMID: 26983989 PMCID: PMC4990112 DOI: 10.1093/jrr/rrw027] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Revised: 01/31/2016] [Accepted: 02/09/2016] [Indexed: 06/05/2023]
Abstract
The E3 ubiquitin ligases ring finger protein (RNF) 8 and RNF168 transduce the DNA double-strand break (DSB) response (DDR) signal by ubiquitinating DSB sites. The depletion of RNF8 or RNF168 suppresses the accumulation of DNA-repair regulating factors such as 53BP1 and RAP80 at DSB sites, suggesting roles for RNF8- and RNF168-mediated ubiquitination in DSB repair. This mini-review provides a brief overview of the RNF8- and RNF168-dependent DDR-signaling and DNA-repair pathways. The choice of DNA-repair pathway when RNF8- and RNF168-mediated ubiquitination-dependent DDR signaling is negatively regulated by deubiquitinating enzymes (DUBs) is reviewed to clarify how the opposing roles of RNF8/RNF168 and DUBs regulate ubiquitination-dependent DDR signaling and the choice of DNA-repair pathway.
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Affiliation(s)
- Shinichiro Nakada
- Department of Bioregulation and Cellular Response, Graduate School of Medicine, Osaka University, Osaka, 565-0871, Japan
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29
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Zhu S, Peng A. Non-homologous end joining repair in Xenopus egg extract. Sci Rep 2016; 6:27797. [PMID: 27324260 PMCID: PMC4914968 DOI: 10.1038/srep27797] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Accepted: 05/25/2016] [Indexed: 11/09/2022] Open
Abstract
Non-homologous end joining (NHEJ) is a major DNA double-strand break (DSB) repair mechanism. We characterized here a series of plasmid-based DSB templates that were repaired in Xenopus egg extracts via the canonical, Ku-dependent NHEJ pathway. We showed that the template with compatible ends was efficiently repaired without end processing, in a manner that required the kinase activity of DNA-PKcs but not ATM. Moreover, non-compatible ends with blunt/3'-overhang, blunt/5'-overhang, and 3'-overhang/5'-overhang were predominantly repaired with fill-in and ligation without the removal of end nucleotides. In contrast, 3'-overhang/3'-overhang and 5'-overhang/5'-overhang templates were processed by resection of 3-5 bases and fill-in of 1-4 bases prior to end ligation. Therefore, the NHEJ machinery exhibited a strong preference for precise repair; the presence of neither non-compatible ends nor protruding single strand DNA sufficiently warranted the action of nucleases. ATM was required for the efficient repair of all non-compatible ends including those repaired without end processing by nucleases, suggesting its role beyond phosphorylation and regulation of Artemis. Finally, dephosphorylation of the 5'-overhang/3'-overhang template reduced the efficiency of DNA repair without increasing the risk of end resection, indicating that end protection via prompt end ligation is not the sole mechanism that suppresses the action of nucleases.
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Affiliation(s)
- Songli Zhu
- Department of Oral Biology, College of Dentistry, University of Nebraska Medical Center, Lincoln, NE 68583, USA
| | - Aimin Peng
- Department of Oral Biology, College of Dentistry, University of Nebraska Medical Center, Lincoln, NE 68583, USA
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30
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Liang Z, Sunder S, Nallasivam S, Wilson TE. Overhang polarity of chromosomal double-strand breaks impacts kinetics and fidelity of yeast non-homologous end joining. Nucleic Acids Res 2016; 44:2769-81. [PMID: 26773053 PMCID: PMC4824102 DOI: 10.1093/nar/gkw013] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Accepted: 01/05/2016] [Indexed: 12/21/2022] Open
Abstract
Non-homologous end joining (NHEJ) is the main repair pathway for DNA double-strand breaks (DSBs) in cells with limited 5′ resection. To better understand how overhang polarity of chromosomal DSBs affects NHEJ, we made site-specific 5′-overhanging DSBs (5′ DSBs) in yeast using an optimized zinc finger nuclease at an efficiency that approached HO-induced 3′ DSB formation. When controlled for the extent of DSB formation, repair monitoring suggested that chromosomal 5′ DSBs were rejoined more efficiently than 3′ DSBs, consistent with a robust recruitment of NHEJ proteins to 5′ DSBs. Ligation-mediated qPCR revealed that Mre11-Rad50-Xrs2 rapidly modified 5′ DSBs and facilitated protection of 3′ DSBs, likely through recognition of overhang polarity by the Mre11 nuclease. Next-generation sequencing revealed that NHEJ at 5′ DSBs had a higher mutation frequency, and validated the differential requirement of Pol4 polymerase at 3′ and 5′ DSBs. The end processing enzyme Tdp1 did not impact joining fidelity at chromosomal 5′ DSBs as in previous plasmid studies, although Tdp1 was recruited to only 5′ DSBs in a Ku-independent manner. These results suggest distinct DSB handling based on overhang polarity that impacts NHEJ kinetics and fidelity through differential recruitment and action of DSB modifying enzymes.
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Affiliation(s)
- Zhuobin Liang
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Sham Sunder
- Department of Human Genetics, University of Michigan, Ann Arbor, MI 48109, USA
| | | | - Thomas E Wilson
- Department of Human Genetics, University of Michigan, Ann Arbor, MI 48109, USA Department of Pathology, University of Michigan, Ann Arbor, MI 48109, USA
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31
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How cancer cells hijack DNA double-strand break repair pathways to gain genomic instability. Biochem J 2015; 471:1-11. [PMID: 26392571 DOI: 10.1042/bj20150582] [Citation(s) in RCA: 69] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
DNA DSBs (double-strand breaks) are a significant threat to the viability of a normal cell, since they can result in loss of genetic material if mitosis or replication is attempted in their presence. Consequently, evolutionary pressure has resulted in multiple pathways and responses to enable DSBs to be repaired efficiently and faithfully. Cancer cells, which are under pressure to gain genomic instability, have a striking ability to avoid the elegant mechanisms by which normal cells maintain genomic stability. Current models suggest that, in normal cells, DSB repair occurs in a hierarchical manner that promotes rapid and efficient rejoining first, with the utilization of additional steps or pathways of diminished accuracy if rejoining is unsuccessful or delayed. In the present review, we evaluate the fidelity of DSB repair pathways and discuss how cancer cells promote the utilization of less accurate processes. Homologous recombination serves to promote accuracy and stability during replication, providing a battlefield for cancer to gain instability. Non-homologous end-joining, a major DSB repair pathway in mammalian cells, usually operates with high fidelity and only switches to less faithful modes if timely repair fails. The transition step is finely tuned and provides another point of attack during tumour progression. In addition to DSB repair, a DSB signalling response activates processes such as cell cycle checkpoint arrest, which enhance the possibility of accurate DSB repair. We consider the ways by which cancers modify and hijack these processes to gain genomic instability.
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32
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Wang Y, Guo Z, Chen X, Zhang W, Lu A, Wang Y. Multi-scale modeling of cell survival and death mediated by the p53 network: a systems pharmacology framework. MOLECULAR BIOSYSTEMS 2015; 11:3011-21. [DOI: 10.1039/c5mb00304k] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The determination of cell fate is a key regulatory process for the development of complex organisms that are controlled by distinct genes in mammalian cells.
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Affiliation(s)
- Yuan Wang
- Lab of Systems Pharmacology
- Center of Bioinformatics
- College of Life Science
- Northwest A&F University
- Yangling
| | - Zihu Guo
- Lab of Systems Pharmacology
- Center of Bioinformatics
- College of Life Science
- Northwest A&F University
- Yangling
| | - Xuetong Chen
- Lab of Systems Pharmacology
- Center of Bioinformatics
- College of Life Science
- Northwest A&F University
- Yangling
| | - Wenjuan Zhang
- Lab of Systems Pharmacology
- Center of Bioinformatics
- College of Life Science
- Northwest A&F University
- Yangling
| | - Aiping Lu
- School of Chinese Medicine
- Hong Kong Baptist University
- Kowloon Tong
- Hong Kong
| | - Yonghua Wang
- Lab of Systems Pharmacology
- Center of Bioinformatics
- College of Life Science
- Northwest A&F University
- Yangling
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33
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Abstract
Double-strand breaks (DSB) in genomic DNA are induced by ionizing radiation or radiomimetic drugs but also occur spontaneously during the cell cycle at quite significant frequencies. In vertebrate cells, nonhomologous DNA end joining (NHEJ) is considered the major pathway of DSB repair which is able to rejoin two broken DNA termini directly end-to-end irrespective of sequence and structure. Genetic studies in various radiosensitive and DSB repair-deficient cell lines yielded insight into the factors involved in NHEJ. Studies in cell-free systems derived from Xenopus eggs and mammalian cells allowed the dissection of the underlying mechanisms. In the present chapter, we describe a protocol for the preparation of whole cell extracts from mammalian cells and a plasmid-based in vitro assay which permits the easy analysis of the efficiency and fidelity of DSB repair via NHEJ in different cell types.
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34
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The fidelity of the ligation step determines how ends are resolved during nonhomologous end joining. Nat Commun 2014; 5:4286. [PMID: 24989324 PMCID: PMC4107315 DOI: 10.1038/ncomms5286] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2014] [Accepted: 06/03/2014] [Indexed: 12/21/2022] Open
Abstract
Nonhomologous end joining (NHEJ) can effectively resolve chromosome breaks despite diverse end structures, but it is unclear how the steps employed for resolution are determined. We sought to address this question by analyzing cellular NHEJ of ends with systematically mispaired and damaged termini. We show NHEJ is uniquely proficient at bypassing subtle terminal mispairs and radiomimetic damage by direct ligation. Nevertheless, bypass ability varies widely, with increases in mispair severity gradually reducing bypass products from 85% to 6%. End-processing by nucleases and polymerases is increased to compensate, though paths with the fewest number of steps to generate a substrate suitable for ligation are favored. Thus, both the frequency and nature of end processing are tailored to meet the needs of the ligation step. We propose a model where the ligase organizes all steps during NHEJ within the stable paired-end complex to limit end processing and associated errors.
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35
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Kim S, Kim D, Cho SW, Kim J, Kim JS. Highly efficient RNA-guided genome editing in human cells via delivery of purified Cas9 ribonucleoproteins. Genome Res 2014; 24:1012-9. [PMID: 24696461 PMCID: PMC4032847 DOI: 10.1101/gr.171322.113] [Citation(s) in RCA: 1249] [Impact Index Per Article: 124.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2013] [Accepted: 03/25/2014] [Indexed: 12/16/2022]
Abstract
RNA-guided engineered nucleases (RGENs) derived from the prokaryotic adaptive immune system known as CRISPR (clustered, regularly interspaced, short palindromic repeat)/Cas (CRISPR-associated) enable genome editing in human cell lines, animals, and plants, but are limited by off-target effects and unwanted integration of DNA segments derived from plasmids encoding Cas9 and guide RNA at both on-target and off-target sites in the genome. Here, we deliver purified recombinant Cas9 protein and guide RNA into cultured human cells including hard-to-transfect fibroblasts and pluripotent stem cells. RGEN ribonucleoproteins (RNPs) induce site-specific mutations at frequencies of up to 79%, while reducing off-target mutations associated with plasmid transfection at off-target sites that differ by one or two nucleotides from on-target sites. RGEN RNPs cleave chromosomal DNA almost immediately after delivery and are degraded rapidly in cells, reducing off-target effects. Furthermore, RNP delivery is less stressful to human embryonic stem cells, producing at least twofold more colonies than does plasmid transfection.
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Affiliation(s)
- Sojung Kim
- Department of Chemistry, Seoul National University, Seoul 151-747, South Korea
- Center for Genome Engineering, Institute for Basic Science, Seoul 151-747, South Korea
| | - Daesik Kim
- Department of Chemistry, Seoul National University, Seoul 151-747, South Korea
- Center for Genome Engineering, Institute for Basic Science, Seoul 151-747, South Korea
| | - Seung Woo Cho
- Department of Chemistry, Seoul National University, Seoul 151-747, South Korea
- Center for Genome Engineering, Institute for Basic Science, Seoul 151-747, South Korea
| | - Jungeun Kim
- Department of Chemistry, Seoul National University, Seoul 151-747, South Korea
- Center for Genome Engineering, Institute for Basic Science, Seoul 151-747, South Korea
| | - Jin-Soo Kim
- Department of Chemistry, Seoul National University, Seoul 151-747, South Korea
- Center for Genome Engineering, Institute for Basic Science, Seoul 151-747, South Korea
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36
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Ramakrishna S, Kwaku Dad AB, Beloor J, Gopalappa R, Lee SK, Kim H. Gene disruption by cell-penetrating peptide-mediated delivery of Cas9 protein and guide RNA. Genome Res 2014; 24:1020-7. [PMID: 24696462 PMCID: PMC4032848 DOI: 10.1101/gr.171264.113] [Citation(s) in RCA: 466] [Impact Index Per Article: 46.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2013] [Accepted: 03/25/2014] [Indexed: 12/26/2022]
Abstract
RNA-guided endonucleases (RGENs) derived from the CRISPR/Cas system represent an efficient tool for genome editing. RGENs consist of two components: Cas9 protein and guide RNA. Plasmid-mediated delivery of these components into cells can result in uncontrolled integration of the plasmid sequence into the host genome, and unwanted immune responses and potential safety problems that can be caused by the bacterial sequences. Furthermore, this delivery method requires transfection tools. Here we show that simple treatment with cell-penetrating peptide (CPP)-conjugated recombinant Cas9 protein and CPP-complexed guide RNAs leads to endogenous gene disruptions in human cell lines. The Cas9 protein was conjugated to CPP via a thioether bond, whereas the guide RNA was complexed with CPP, forming condensed, positively charged nanoparticles. Simultaneous and sequential treatment of human cells, including embryonic stem cells, dermal fibroblasts, HEK293T cells, HeLa cells, and embryonic carcinoma cells, with the modified Cas9 and guide RNA, leads to efficient gene disruptions with reduced off-target mutations relative to plasmid transfections, resulting in the generation of clones containing RGEN-induced mutations. Our CPP-mediated RGEN delivery process provides a plasmid-free and additional transfection reagent-free method to use this tool with reduced off-target effects. We envision that our method will facilitate RGEN-directed genome editing.
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Affiliation(s)
- Suresh Ramakrishna
- Graduate School of Biomedical Science and Engineering/College of Medicine, Hanyang University, Seoul 133-791, Republic of Korea
| | - Abu-Bonsrah Kwaku Dad
- Graduate School of Biomedical Science and Engineering/College of Medicine, Hanyang University, Seoul 133-791, Republic of Korea
| | - Jagadish Beloor
- Department of Bioengineering and Institute for Bioengineering and Biopharmaceutical Research, Hanyang University, Seoul 133-791, Republic of Korea
| | - Ramu Gopalappa
- Graduate School of Biomedical Science and Engineering/College of Medicine, Hanyang University, Seoul 133-791, Republic of Korea
| | - Sang-Kyung Lee
- Department of Bioengineering and Institute for Bioengineering and Biopharmaceutical Research, Hanyang University, Seoul 133-791, Republic of Korea
| | - Hyongbum Kim
- Graduate School of Biomedical Science and Engineering/College of Medicine, Hanyang University, Seoul 133-791, Republic of Korea
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38
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Abstract
Nonhomologous end joining repairs DNA double-strand breaks created by ionizing radiation and V(D)J recombination. Ku, XRCC4/Ligase IV (XL), and XLF have a remarkable mismatched end (MEnd) ligase activity, particularly for ends with mismatched 3' overhangs, but the mechanism has remained obscure. Here, we showed XL required Ku to bind DNA, whereas XLF required both Ku and XL to bind DNA. We detected cooperative assembly of one or two Ku molecules and up to five molecules each of XL and XLF into a Ku-XL-XLF-DNA (MEnd ligase-DNA) complex. XLF mutations that disrupted its interactions with XRCC4 or DNA also disrupted complex assembly and end joining. Together with published co-crystal structures of truncated XRCC4 and XLF proteins, our data with full-length Ku, XL, and XLF bound to DNA indicate assembly of a filament containing Ku plus alternating XL and XLF molecules. By contrast, in the absence of XLF, we detected cooperative assembly of up to six molecules each of Ku and XL into a Ku-XL-DNA complex, consistent with a filament containing alternating Ku and XL molecules. Despite a lower molecular mass, MEnd ligase-DNA had a lower electrophoretic mobility than Ku-XL-DNA. The anomalous difference in mobility and difference in XL to Ku molar ratio suggests that MEnd ligase-DNA has a distinct structure that successfully aligns mismatched DNA ends for ligation.
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Affiliation(s)
- Chun J Tsai
- Department of Medicine, Stanford University School of Medicine, Stanford, California 94305, USA
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Li Y, Zhao D. Basics of Molecular Biology. ADVANCED TOPICS IN SCIENCE AND TECHNOLOGY IN CHINA 2013. [PMCID: PMC7122053 DOI: 10.1007/978-3-642-34303-2_16] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Molecular biology is the study of biology on molecular level. The field overlaps with areas of biology and chemistry, particularly genetics and biochemistry. Molecular biology chiefly concerns itself with understanding the interactions between the various systems of a cell, including the interactions between DNA (deoxyribonucleic acid), RNA (Ribonucleic acid) and protein biosynthesis as well as learning how these interactions are regulated[1].
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Reynolds P, Anderson JA, Harper JV, Hill MA, Botchway SW, Parker AW, O'Neill P. The dynamics of Ku70/80 and DNA-PKcs at DSBs induced by ionizing radiation is dependent on the complexity of damage. Nucleic Acids Res 2012; 40:10821-31. [PMID: 23012265 PMCID: PMC3510491 DOI: 10.1093/nar/gks879] [Citation(s) in RCA: 90] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
DNA double-strand breaks (DSBs) are biologically one of the most important cellular lesions and possess varying degrees of chemical complexity. The notion that the repairability of more chemically complex DSBs is inefficient led to the concept that the extent of DSB complexity underlies the severity of the biological consequences. The repair of DSBs by non-homologous end joining (NHEJ) has been extensively studied but it remains unknown whether more complex DSBs require a different sub-set of NHEJ protein for their repair compared with simple DSBs. To address this, we have induced DSBs in fluorescently tagged mammalian cells (Ku80-EGFP, DNA-PKcs-YFP or XRCC4-GFP, key proteins in NHEJ) using ultra-soft X-rays (USX) or multi-photon near infrared (NIR) laser irradiation. We have shown in real-time that simple DSBs, induced by USX or NIR microbeam irradiation, are repaired rapidly involving Ku70/80 and XRCC4/Ligase IV/XLF. In contrast, DSBs with greater chemical complexity are repaired slowly involving not only Ku70/80 and XRCC4/Ligase IV/XLF but also DNA-PKcs. Ataxia telangiectasia-mutated inhibition only retards repair of the more chemically complex DSBs which require DNA-PKcs. In summary, the repair of DSBs by NHEJ is highly regulated with pathway choice and kinetics of repair dependent on the chemical complexity of the DSB.
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Affiliation(s)
- Pamela Reynolds
- Department of Oncology, Gray Institute for Radiation Oncology & Biology, University of Oxford, Oxford OX3 7DQ, UK
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41
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Thompson LH. Recognition, signaling, and repair of DNA double-strand breaks produced by ionizing radiation in mammalian cells: the molecular choreography. Mutat Res 2012; 751:158-246. [PMID: 22743550 DOI: 10.1016/j.mrrev.2012.06.002] [Citation(s) in RCA: 261] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2011] [Revised: 06/09/2012] [Accepted: 06/16/2012] [Indexed: 12/15/2022]
Abstract
The faithful maintenance of chromosome continuity in human cells during DNA replication and repair is critical for preventing the conversion of normal diploid cells to an oncogenic state. The evolution of higher eukaryotic cells endowed them with a large genetic investment in the molecular machinery that ensures chromosome stability. In mammalian and other vertebrate cells, the elimination of double-strand breaks with minimal nucleotide sequence change involves the spatiotemporal orchestration of a seemingly endless number of proteins ranging in their action from the nucleotide level to nucleosome organization and chromosome architecture. DNA DSBs trigger a myriad of post-translational modifications that alter catalytic activities and the specificity of protein interactions: phosphorylation, acetylation, methylation, ubiquitylation, and SUMOylation, followed by the reversal of these changes as repair is completed. "Superfluous" protein recruitment to damage sites, functional redundancy, and alternative pathways ensure that DSB repair is extremely efficient, both quantitatively and qualitatively. This review strives to integrate the information about the molecular mechanisms of DSB repair that has emerged over the last two decades with a focus on DSBs produced by the prototype agent ionizing radiation (IR). The exponential growth of molecular studies, heavily driven by RNA knockdown technology, now reveals an outline of how many key protein players in genome stability and cancer biology perform their interwoven tasks, e.g. ATM, ATR, DNA-PK, Chk1, Chk2, PARP1/2/3, 53BP1, BRCA1, BRCA2, BLM, RAD51, and the MRE11-RAD50-NBS1 complex. Thus, the nature of the intricate coordination of repair processes with cell cycle progression is becoming apparent. This review also links molecular abnormalities to cellular pathology as much a possible and provides a framework of temporal relationships.
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Affiliation(s)
- Larry H Thompson
- Biology & Biotechnology Division, L452, Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, CA 94551-0808, United States.
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Chiruvella KK, Sebastian R, Sharma S, Karande AA, Choudhary B, Raghavan SC. Time-Dependent Predominance of Nonhomologous DNA End-Joining Pathways during Embryonic Development in Mice. J Mol Biol 2012; 417:197-211. [DOI: 10.1016/j.jmb.2012.01.029] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2011] [Revised: 01/18/2012] [Accepted: 01/20/2012] [Indexed: 12/26/2022]
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Chayot R, Montagne B, Ricchetti M. DNA polymerase μ is a global player in the repair of non-homologous end-joining substrates. DNA Repair (Amst) 2012; 11:22-34. [DOI: 10.1016/j.dnarep.2011.09.016] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2010] [Revised: 09/23/2011] [Accepted: 09/27/2011] [Indexed: 12/25/2022]
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The NF90/NF45 complex participates in DNA break repair via nonhomologous end joining. Mol Cell Biol 2011; 31:4832-43. [PMID: 21969602 DOI: 10.1128/mcb.05849-11] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Nuclear factor 90 (NF90), an RNA-binding protein implicated in the regulation of gene expression, exists as a heterodimeric complex with NF45. We previously reported that depletion of the NF90/NF45 complex results in a multinucleated phenotype. Time-lapse microscopy revealed that binucleated cells arise by incomplete abscission of progeny cells followed by fusion. Multinucleate cells arose through aberrant division of binucleated cells and displayed abnormal metaphase plates and anaphase chromatin bridges suggestive of DNA repair defects. NF90 and NF45 are known to interact with the DNA-dependent protein kinase (DNA-PK), which is involved in telomere maintenance and DNA repair by nonhomologous end joining (NHEJ). We hypothesized that NF90 modulates the activity of DNA-PK. In an in vitro NHEJ assay system, DNA end joining was reduced by NF90/NF45 immunodepletion or by RNA digestion to an extent similar to that for catalytic subunit DNA-PKcs immunodepletion. In vivo, NF90/NF45-depleted cells displayed increased γ-histone 2A.X foci, indicative of an accumulation of double-strand DNA breaks (DSBs), and increased sensitivity to ionizing radiation consistent with decreased DSB repair. Further, NF90/NF45 knockdown reduced end-joining activity in vivo. These results identify the NF90/NF45 complex as a regulator of DNA damage repair mediated by DNA-PK and suggest that structured RNA may modulate this process.
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Qi J, Ding Y, Zhu Y, Wu Y. Kinetic theory approach to modeling of cellular repair mechanisms under genome stress. PLoS One 2011; 6:e22228. [PMID: 21857915 PMCID: PMC3153456 DOI: 10.1371/journal.pone.0022228] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2011] [Accepted: 06/17/2011] [Indexed: 01/08/2023] Open
Abstract
Under acute perturbations from outer environment, a normal cell can trigger cellular self-defense mechanism in response to genome stress. To investigate the kinetics of cellular self-repair process at single cell level further, a model of DNA damage generating and repair is proposed under acute Ion Radiation (IR) by using mathematical framework of kinetic theory of active particles (KTAP). Firstly, we focus on illustrating the profile of Cellular Repair System (CRS) instituted by two sub-populations, each of which is made up of the active particles with different discrete states. Then, we implement the mathematical framework of cellular self-repair mechanism, and illustrate the dynamic processes of Double Strand Breaks (DSBs) and Repair Protein (RP) generating, DSB-protein complexes (DSBCs) synthesizing, and toxins accumulating. Finally, we roughly analyze the capability of cellular self-repair mechanism, cellular activity of transferring DNA damage, and genome stability, especially the different fates of a certain cell before and after the time thresholds of IR perturbations that a cell can tolerate maximally under different IR perturbation circumstances.
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Affiliation(s)
- Jinpeng Qi
- College of Information Science and Technology, Donghua University, Shanghai, People's Republic of China.
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DNA binding proteins: outline of functional classification. Biomol Concepts 2011; 2:293-303. [DOI: 10.1515/bmc.2011.023] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2011] [Accepted: 05/23/2011] [Indexed: 01/12/2023] Open
Abstract
AbstractDNA-binding proteins composed of DNA-binding domains directly affect genomic functions, mainly by performing transcription, DNA replication or DNA repair. Here, we briefly describe the DNA-binding proteins according to these three major functions. Transcription factors that usually bind to specific sequences of DNA could be classified based on their sequence similarity and the structure of the DNA-binding domains, such as basic, zinc-coordinating, helix-turn-helix domains, etc. Most DNA replication factors do not need a specific sequence of DNA, but instead mainly depend on a DNA structure, with the exception of the origin recognition complex in yeast or Escherichia coli that recognizes the DNA sequences at particular origins. DNA replication includes initiation and elongation. The major DNA-binding proteins involved in these two steps are briefly described. DNA repair proteins bound to DNA depend on the damaged DNA structure. They are classified to base excision repair, DNA mismatch repair, nucleotide excision repair, homologous recombination repair and non-homologous end joining. The major DNA-binding proteins involved in these pathways are briefly described. Histone and high mobility group are two examples of DNA-binding proteins that do not belong to the three categories above and are briefly described. Finally, we warn that the non-specific binding proteins might have an affinity to some non-specific medium materials such as protein A or G beads that are commonly used for immune precipitation, which can easily generate false positive signals while detecting protein-protein interaction; therefore, the results need to be carefully analyzed using positive/negative controls.
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47
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Modeling non-homologous end joining. J Theor Biol 2011; 283:122-35. [DOI: 10.1016/j.jtbi.2011.05.015] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2011] [Accepted: 05/11/2011] [Indexed: 11/22/2022]
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48
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Pawelczak KS, Bennett SM, Turchi JJ. Coordination of DNA-PK activation and nuclease processing of DNA termini in NHEJ. Antioxid Redox Signal 2011; 14:2531-43. [PMID: 20698792 PMCID: PMC3096510 DOI: 10.1089/ars.2010.3368] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
DNA double-strand breaks (DSB), particularly those induced by ionizing radiation (IR), are complex lesions that can be cytotoxic if not properly repaired. IR-induced DSB often have DNA termini modifications, including thymine glycols, ring fragmentation, 3'-phosphoglycolates, 5'-hydroxyl groups, and abasic sites. Nonhomologous end joining (NHEJ) is a major pathway responsible for the repair of these complex breaks. Proteins involved in NHEJ include the Ku 70/80 heterodimer, DNA-PKcs, processing proteins including Artemis and DNA polymerases μ and λ, XRCC4, DNA ligase IV, and XLF. We will discuss the role of the physical and functional interactions of DNA-PK as a result of activation, with an emphasis on DNA structure, chemistry, and sequence. With the diversity of IR induced DSB, it is becoming increasingly clear that multiple DNA processing enzymes are likely necessary for effective repair of a break. We will explore the roles of several important processing enzymes, with a focus on the nuclease Artemis and its role in processing diverse DSB. The effect of DNA termini on both DNA-PK and Artemis activity will be analyzed from a structural and biochemical view.
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Affiliation(s)
- Katherine S Pawelczak
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, 980 W. Walnut St., Indianapolis, IN 46202, USA
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Beck BD, Lee SS, Williamson E, Hromas RA, Lee SH. Biochemical characterization of metnase's endonuclease activity and its role in NHEJ repair. Biochemistry 2011; 50:4360-70. [PMID: 21491884 PMCID: PMC3388547 DOI: 10.1021/bi200333k] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Metnase (SETMAR) is a SET-transposase fusion protein that promotes nonhomologous end joining (NHEJ) repair in humans. Although both SET and the transposase domains were necessary for its function in DSB repair, it is not clear what specific role Metnase plays in the NHEJ. In this study, we show that Metnase possesses a unique endonuclease activity that preferentially acts on ssDNA and ssDNA-overhang of a partial duplex DNA. Cell extracts lacking Metnase poorly supported DNA end joining, and addition of wt-Metnase to cell extracts lacking Metnase markedly stimulated DNA end joining, while a mutant (D483A) lacking endonuclease activity did not. Given that Metnase overexpression enhanced DNA end processing in vitro, our finding suggests a role for Metnase's endonuclease activity in promoting the joining of noncompatible ends.
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Affiliation(s)
- Brian D. Beck
- Department of Biochemistry & Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA
| | - Sung-Sook Lee
- Department of Biochemistry & Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA
| | - Elizabeth Williamson
- Department of Medicine, University of Florida and Shands Health Care System, Gainesville, Florida 32610, USA
| | - Robert A. Hromas
- Department of Medicine, University of Florida and Shands Health Care System, Gainesville, Florida 32610, USA
| | - Suk-Hee Lee
- Department of Biochemistry & Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA
- Indiana University Simon Cancer Center, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA
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50
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A Mathematical Framework for Cellular Repair Mechanisms under Genomic Stress Based on Kinetic Theory Approach. ACTA ACUST UNITED AC 2011. [DOI: 10.4028/www.scientific.net/amm.52-54.7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Generally, a cell can trigger its self-defense mechanism in response to genomic stress under acute perturbations from outer environment. To investigate the dynamic kinetics of cellular repair mechanisms in fighting against genomic stress, a mathematical model of representing and analyzing DNA damage generation and repair process is proposed under acute Ion Radiation (IR) by using the Kinetic Theory of Active Particles (KTAP). In this paper, we focus on describing a mathematical framework of Cellular Repair System (CRS). We also present the dynamic processes of Double Strand Breaks (DSBs) and Repair Protein (RP) generating, DSB-protein complexes (DSBCs) synthesizing, and toxins accumulating under continuous radiation time.
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